The 1985 central chile earthquake: a repeat of previous great earthquakes in the region?

PubMed

Comte, D; Eisenberg, A; Lorca, E; Pardo, M; Ponce, L; Saragoni, R; Singh, S K; Suárez, G

1986-07-25

A great earthquake (surface-wave magnitude, 7.8) occurred along the coast of central Chile on 3 March 1985, causing heavy damage to coastal towns. Intense foreshock activity near the epicenter of the main shock occurred for 11 days before the earthquake. The aftershocks of the 1985 earthquake define a rupture area of 170 by 110 square kilometers. The earthquake was forecast on the basis of the nearly constant repeat time (83 +/- 9 years) of great earthquakes in this region. An analysis of previous earthquakes suggests that the rupture lengths of great shocks in the region vary by a factor of about 3. The nearly constant repeat time and variable rupture lengths cannot be reconciled with time- or slip-predictable models of earthquake recurrence. The great earthquakes in the region seem to involve a variable rupture mode and yet, for unknown reasons, remain periodic. Historical data suggest that the region south of the 1985 rupture zone should now be considered a gap of high seismic potential that may rupture in a great earthquake in the next few tens of years.

Structure of the 1906 near-surface rupture zone of the San Andreas Fault, San Francisco Peninsula segment, near Woodside, California

USGS Publications Warehouse

Rosa, C.M.; Catchings, R.D.; Rymer, M.J.; Grove, Karen; Goldman, M.R.

2016-07-08

High-resolution seismic-reflection and refraction images of the 1906 surface rupture zone of the San Andreas Fault near Woodside, California reveal evidence for one or more additional near-surface (within about 3 meters [m] depth) fault strands within about 25 m of the 1906 surface rupture. The 1906 surface rupture above the groundwater table (vadose zone) has been observed in paleoseismic trenches that coincide with our seismic profile and is seismically characterized by a discrete zone of low P-wave velocities (Vp), low S-wave velocities (Vs), high Vp/Vs ratios, and high Poisson’s ratios. A second near-surface fault strand, located about 17 m to the southwest of the 1906 surface rupture, is inferred by similar seismic anomalies. Between these two near-surface fault strands and below 5 m depth, we observed a near-vertical fault strand characterized by a zone of high Vp, low Vs, high Vp/Vs ratios, and high Poisson’s ratios on refraction tomography images and near-vertical diffractions on seismic-reflection images. This prominent subsurface zone of seismic anomalies is laterally offset from the 1906 surface rupture by about 8 m and likely represents the active main (long-term) strand of the San Andreas Fault at 5 to 10 m depth. Geometries of the near-surface and subsurface (about 5 to 10 m depth) fault zone suggest that the 1906 surface rupture dips southwestward to join the main strand of the San Andreas Fault at about 5 to 10 m below the surface. The 1906 surface rupture forms a prominent groundwater barrier in the upper 3 to 5 m, but our interpreted secondary near-surface fault strand to the southwest forms a weaker barrier, suggesting that there has been less or less-recent near-surface slip on that strand. At about 6 m depth, the main strand of the San Andreas Fault consists of water-saturated blue clay (collected from a hand-augered borehole), which is similar to deeply weathered serpentinite observed within the main strand of the San Andreas Fault at nearby sites. Multiple fault strands in the area of the 1906 surface rupture may account for variations in geologic slip rates calculated from several paleoseismic sites along the Peninsula segment of the San Andreas Fault.t.

Dynamic rupture modeling of thrust faults with parallel surface traces.

NASA Astrophysics Data System (ADS)

Peshette, P.; Lozos, J.; Yule, D.

2017-12-01

Fold and thrust belts (such as those found in the Himalaya or California Transverse Ranges) consist of many neighboring thrust faults in a variety of geometries. Active thrusts within these belts individually contribute to regional seismic hazard, but further investigation is needed regarding the possibility of multi-fault rupture in a single event. Past analyses of historic thrust surface traces suggest that rupture within a single event can jump up to 12 km. There is also observational precedent for long distance triggering between subparallel thrusts (e.g. the 1997 Harnai, Pakistan events, separated by 50 km). However, previous modeling studies find a maximum jumping rupture distance between thrust faults of merely 200 m. Here, we present a new dynamic rupture modeling parameter study that attempts to reconcile these differences and determine which geometrical and stress conditions promote jumping rupture. We use a community verified 3D finite element method to model rupture on pairs of thrust faults with parallel surface traces. We vary stress drop and fault strength to determine which conditions produce jumping rupture at different dip angles and different separations between surface traces. This parameter study may help to understand the likelihood of jumping rupture in real-world thrust systems, and may thereby improve earthquake hazard assessment.

Rupture of poly implant prothèse silicone breast implants: an implant retrieval study.

PubMed

Swarts, Eric; Kop, Alan M; Nilasaroya, Anastasia; Keogh, Catherine V; Cooper, Timothy

2013-04-01

Poly Implant Prothèse implants were recalled in Australia in April of 2010 following concerns of higher than expected rupture rates and the use of unauthorized industrial grade silicone as a filler material. Although subsequent investigations found that the gel filler material does not pose a threat to human health, the important question of what caused a relatively modern breast implant to have such a poor outcome compared with contemporary silicone breast implants is yet to be addressed. From a cohort of 27 patients, 19 ruptured Poly Implant Prothèse breast implants were subjected to a range of mechanical tests and microscopic/macroscopic investigations to evaluate possible changes in properties as a result of implantation. New Poly Implant Prothèse implants were used as controls. All samples, explanted and controls, complied with the requirements for shell integrity as specified in the International Organization for Standardization 14607. Compression testing revealed rupture rates similar to those reported in the literature. Shell thickness was highly variable, with most shells having regions below the minimum thickness of 0.57 mm that was specified by the manufacturer. Potential regions of stress concentration were observed on the smooth inner surfaces and outer textured surfaces. The high incidence of Poly Implant Prothèse shell rupture is most likely a result of inadequate quality control, with contributory factors being shell thickness variation and manufacturing defects on both inner and outer surfaces of the shell. No evidence of shell degradation with implantation time was determined.

The 2013 Mw 6.2 Khaki-Shonbe (Iran) Earthquake: Seismic Shortening of the Zagros Sedimentary Cover

NASA Astrophysics Data System (ADS)

Elliott, J. R.; Bergman, E.; Copley, A.; Ghods, A.; Nissen, E.; Oveisi, B.; Walters, R. J.

2014-12-01

The 2013 Mw 6.2 Khaki-Shonbe earthquake occurred in the Simply Folded Belt of the Zagros Mountains, Iran. This is the largest earthquake in the Zagros since the November 1990 Mw 6.4 Furg (Hormozgan) thrust faulting event, and therefore the largest in the period for which dense InSAR ground displacements are available. It is also the biggest seismic event to have occurred in the Simply Folded Belt since the March 1977 Mw 6.7 Khurgu earthquake. This earthquake therefore potentially provides valuable insights into a range of controversies: (1) the preponderance of earthquake faulting in the crystalline basement versus the sedimentary cover and the potential importance of lithology in controlling and limiting seismic rupture; (2) the nature of surface folding and whether or not there is a one-to-one relationship between buried reverse faults and surface anticlines; and (3) the presence or absence of large pulses of aseismic slip triggered by mainshock rupture. We combine seismological solutions and aftershock relocations with satellite interferometric ground displacements and observations from the field to determine the geometry of faulting and its relationship with the structure, stratigraphy and tectonics of the Central Zagros. The earthquake rupture involved reverse slip on two along-strike southwest dipping fault segments, the rupture initiating at the northern and bottom end of the larger north-west segment. These faults verge away from the foreland and towards the high range interior, contrary to the fault geometries depicted in many structural cross-sections of the Zagros. The slip measured on the reverse segments occurred over two mutually exclusive depth ranges, 10-5 km and 4-2 km, resulting in long (16 km), narrow (7 km) rupture segments. Conversely, aftershocks are found to cluster in the depth range 8-16 km, beneath the main rupture segment. This indicates only significant reverse slip and coseismic shortening in the sedimentary cover, with the slip distribution likely to be lithologically controlled in depth by the Hormuz salt at the base of the sedimentary cover, and the Kazhdumi Formation mudrocks at upper-levels (5 km), and aftershocks constrained largely beneath the main coseismic rupture planes.

The susitna glacier thrust fault: Characteristics of surface ruptures on the fault that initiated the 2002 denali fault earthquake

USGS Publications Warehouse

Crone, A.J.; Personius, S.F.; Craw, P.A.; Haeussler, P.J.; Staft, L.A.

2004-01-01

The 3 November 2002 Mw 7.9 Denali fault earthquake sequence initiated on the newly discovered Susitna Glacier thrust fault and caused 48 km of surface rupture. Rupture of the Susitna Glacier fault generated scarps on ice of the Susitna and West Fork glaciers and on tundra and surficial deposits along the southern front of the central Alaska Range. Based on detailed mapping, 27 topographic profiles, and field observations, we document the characteristics and slip distribution of the 2002 ruptures and describe evidence of pre-2002 ruptures on the fault. The 2002 surface faulting produced structures that range from simple folds on a single trace to complex thrust-fault ruptures and pressure ridges on multiple, sinuous strands. The deformation zone is locally more than 1 km wide. We measured a maximum vertical displacement of 5.4 m on the south-directed main thrust. North-directed backthrusts have more than 4 m of surface offset. We measured a well-constrained near-surface fault dip of about 19?? at one site, which is considerably less than seismologically determined values of 35??-48??. Surface-rupture data yield an estimated magnitude of Mw 7.3 for the fault, which is similar to the seismological value of Mw 7.2. Comparison of field and seismological data suggest that the Susitna Glacier fault is part of a large positive flower structure associated with northwest-directed transpressive deformation on the Denali fault. Prehistoric scarps are evidence of previous rupture of the Sustina Glacier fault, but additional work is needed to determine if past failures of the Susitna Glacier fault have consistently induced rupture of the Denali fault.

Natural bactericidal surfaces: mechanical rupture of Pseudomonas aeruginosa cells by cicada wings.

PubMed

Ivanova, Elena P; Hasan, Jafar; Webb, Hayden K; Truong, Vi Khanh; Watson, Gregory S; Watson, Jolanta A; Baulin, Vladimir A; Pogodin, Sergey; Wang, James Y; Tobin, Mark J; Löbbe, Christian; Crawford, Russell J

2012-08-20

Natural superhydrophobic surfaces are often thought to have antibiofouling potential due to their self-cleaning properties. However, when incubated on cicada wings, Pseudomonas aeruginosa cells are not repelled; instead they are penetrated by the nanopillar arrays present on the wing surface, resulting in bacterial cell death. Cicada wings are effective antibacterial, as opposed to antibiofouling, surfaces. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Numerical study of liquid film rupture after droplet spreading on a superhydrophilic surface

NASA Astrophysics Data System (ADS)

Guo, Yisen; Lian, Yongsheng

2017-11-01

When a droplet impacts onto a solid surface, different outcomes can be observed, such as rebound, spreading and splashing. We present numerical simulation results on liquid film rupture after spreading of a droplet impact on a smooth superhydrophilic surface. The Navier-Stokes equations are solved using the variable density pressure projection method and the moment-of-fluid method is used to track the droplet interface. A superhydrophilic or superwetting surface has strong affinity to liquid and we assume the contact angle between solid and liquid is almost zero degree. The droplet spreading and film rupture process occurs in two stages: the droplet first spreads onto the surface and flattens into a thin film as it reaches the maximum diameter, then the film rim becomes unstable and the film rupture initiates from the rim toward the center gradually until the entire film breaks up into secondary droplets. The duration of the film rupture stage is much shorter than the spreading stage. The simulation result is compared with experiment and good agreement is achieved. We investigate the film thickness evolution during spreading and the effect of surface wettability on film rupture.

Rupture Dynamics along Thrust Dipping Fault: Inertia Effects due to Free Surface Wave Interactions

NASA Astrophysics Data System (ADS)

Vilotte, J. P.; Scala, A.; Festa, G.

2017-12-01

We numerically investigate the dynamic interaction between free surface and up-dip, in-plane rupture propagation along thrust faults, under linear slip-weakening friction. With reference to shallow along-dip rupture propagation during large subduction earthquakes, we consider here low dip-angle fault configurations with fixed strength excess and depth-increasing initial stress. In this configuration, the rupture undergoes a break of symmetry with slip-induced normal stress perturbations triggered by the interaction with reflected waves from the free surface. We found that both body-waves - behind the crack front - and surface waves - at the crack front - can trigger inertial effects. When waves interact with the rupture before this latter reaches its asymptotic speed, the rupture can accelerate toward the asymptotic speed faster than in the unbounded symmetric case, as a result of these inertial effects. Moreover, wave interaction at the crack front also affects the slip rate generating large ground motion on the hanging wall. Imposing the same initial normal stress, frictional strength and stress drop while varying the static friction coefficient we found that the break of symmetry makes the rupture dynamics dependent on the absolute value of friction. The higher the friction the stronger the inertial effect both in terms of rupture acceleration and slip amount. When the contact condition allows the fault interface to open close to the free surface, the length of the opening zone is shown to depend on the propagation length, the initial normal stress and the static friction coefficient. These new results are shown to agree with analytical results of rupture propagation in bounded media, and open new perspectives for understanding the shallow rupture of large subduction earthquakes and tsunami sources.

Slip History of the 2008 Mw 7.9 Wenchuan Earthquake Constrained by Joint Inverting Seismic, Geodetic, and Geological Observations

NASA Astrophysics Data System (ADS)

Shao, G.; Ji, C.; Lu, Z.; Hudnut, K. W.; Liu, J.; Zhang, W.

2009-12-01

We study the kinematic rupture process of the 2008 Mw 7.9 Wenchuan earthquake using all geophysical and geological datasets that we are able to access, including the waveforms of teleseismic long period surface waves, broadband body waves and local strong motions, GPS vectors, interferometic radar (INSAR) images, and geological surface offsets. The relocated aftershock locations have also been included to constrain the potential fault geometry. These datasets have very different sensitivities to not only the slip on the fault but also the “a priori” information of the source inversions, such as the local velocity structure and the details of irregular fault surface. Effects have then been made to reconcile these datasets by reasonably perturbing the velocity structure and fault geometry, which are both poorly constrained. We have used two 1D velocity models, one for the Tibet plateau and the other for Sichuan basin, to calculate the static and dynamic earth responses; and developed a complex fault system including two irregular fault planes for Beichuan and Pengguan faults, respectively. The long wavelength errors of the INSAR LOS displacements have also been considered and been corrected simultaneously during the joint inversions. Our preferred model not only explains the geodetic and tele-seismic data very well, but also reasonably matches most strong motion waveforms. According to this result, the Wenchuan earthquake has an unprecedented complex rupture process. It initiated southwest of the town of Yingxiu at a depth of about 12 km, where the low-angle Pengguan fault and the high-angle Beichuan fault intersect. The rupture initiated on the low angle Pengguan fault and then later triggered the rupture on the high angle Beichuan fault. It then unilaterally ruptured northeastward for 270 km, mainly on the Beichuan fault. The entire rupture duration is over 95 seconds with an average rupture velocity of 3.0 km/s. Except for the region near the hypocenter and the region near the northeast end of the rupture, the majority of slip occurred at depths less than 12 km. The total seismic moment released by this earthquake was 1.02 x 1021 Nm, with ~36% on the Pengguan fault. Our analysis also indicates that the aftershock zone along the extension of the Xiaoyudong fault is consistent with the theory of static stress triggering due to the co-seismic rupture.

Rare presentation of ruptured syphilitic aortic aneurysm with pseudoaneurysm.

PubMed

de Almeida Feitosa, Israel Nilton; Dantas Leite Figueiredo, Magda; de Sousa Belem, Lucia; Evelin Soares Filho, Antônio Wilon

2015-11-01

We report the interesting case of a rare form of presentation of rupture of the ascending aorta with formation of a pseudoaneurysm, diagnosed following the development of a large mass on the surface of the chest over a period of about eight months. Serological tests were positive for syphilis. Echocardiography and computed tomography angiography were essential to confirm the diagnosis and therapeutic management. Cardiovascular syphilis is a rare entity since the discovery of penicillin. Rupture of an aortic aneurysm with formation of a pseudoaneurysm is a potentially fatal complication. The postoperative period was uneventful and the patient was discharged from hospital within days of surgery. Copyright © 2015 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Strong nonlinear rupture theory of thin free liquid films

NASA Astrophysics Data System (ADS)

Chi-Chuan, Hwang; Jun-Liang, Chen; Li-Fu, Shen; Cheng-I, Weng

1996-02-01

A simplified governing equation with high-order effects is formulated after a procedure of evaluating the order of magnitude. Furthermore, the nonlinear evolution equations are derived by the Kármán-Polhausen integral method with a specified velocity profile. Particularly, the effects of surface tension, van der Waals potential, inertia and high-order viscous dissipation are taken into consideration in these equation. The numerical results reveal that the rupture time of free film is much shorter than that of a film on a flat plate. It is shown that because of a more complete high-order viscous dissipation effect discussed in the present study, the rupture process of present model is slower than is predicted by the high-order long wave theory.

Spatiotemporal complexity of 2-D rupture nucleation process observed by direct monitoring during large-scale biaxial rock friction experiments

NASA Astrophysics Data System (ADS)

Fukuyama, Eiichi; Tsuchida, Kotoyo; Kawakata, Hironori; Yamashita, Futoshi; Mizoguchi, Kazuo; Xu, Shiqing

2018-05-01

We were able to successfully capture rupture nucleation processes on a 2-D fault surface during large-scale biaxial friction experiments using metagabbro rock specimens. Several rupture nucleation patterns have been detected by a strain gauge array embedded inside the rock specimens as well as by that installed along the edge walls of the fault. In most cases, the unstable rupture started just after the rupture front touched both ends of the rock specimen (i.e., when rupture front extended to the entire width of the fault). In some cases, rupture initiated at multiple locations and the rupture fronts coalesced to generate unstable ruptures, which could only be detected from the observation inside the rock specimen. Therefore, we need to carefully examine the 2-D nucleation process of the rupture especially when analyzing the data measured only outside the rock specimen. At least the measurements should be done at both sides of the fault to identify the asymmetric rupture propagation on the fault surface, although this is not perfect yet. In the present experiment, we observed three typical types of the 2-D rupture propagation patterns, two of which were initiated at a single location either close to the fault edge or inside the fault. This initiation could be accelerated by the free surface effect at the fault edge. The third one was initiated at multiple locations and had a rupture coalescence at the middle of the fault. These geometrically complicated rupture initiation patterns are important for understanding the earthquake nucleation process in nature.

Map showing surface ruptures associated with the Mammoth Lakes, California, earthquakes of May 1980

USGS Publications Warehouse

Clark, M.M.; Yount, J.C.; Vaughn, P.R.; Zepeda, R.L.

1982-01-01

This map shows surface ruptures associated with the M 6 Mammoth Lakes earthquakes of May 25-27, 1980 (Sherburne, 1980). The ruptures were mapped during USGS field investigations May 28 to June 4 and July 14-19, 1980. The map also includes some of the ruptures recorded by California Division of Mines and Geology investigators May 26-31, June 26-27, and July 7-11, 1980 (Taylor and Bryant, 1980). Because most of the surface ruptures developed in either unconsolidated pumice, alluvium, or till (and many were on slopes of scarps created by earlier faulting), wind, rain and animals quickly erased many of the ruptures. In places, the minimum detectable slip was 3-10 mm. Thus the lines on the map do not record all of the ruptures that formed at the time of the earthquake. Many of the areas were we show gaps between lines on the map probably had cracks originally. 

Complex surface rupturing and related formation mechanisms in the Xiaoyudong area for the 2008 Mw 7.9 Wenchuan Earthquake, China

NASA Astrophysics Data System (ADS)

Tan, Xi-bin; Yuan, Ren-mao; Xu, Xi-wei; Chen, Gui-hua; Klinger, Yann; Chang, Chung-Pai; Ren, Jun-jie; Xu, Chong; Li, Kang

2012-09-01

The large oblique reverse slip shock of the 2008 Mw = 7.9 Wenchuan earthquake, China, produced one of the longest and most complicated surface ruptures ever known. The complexity is particularly evident in the Xiaoyudong area, where three special phenomena occurred: the 7 km long Xiaoyudong rupture perpendicular to the Beichuan-Yingxiu fault; the occurrence of two parallel faults rupturing simultaneously, and apparent discontinuity of the Beichuan-Yingxiu rupture. This paper systematically documents these co-seismic rupture phenomena for the Xiaoyudong area. The discussion and results are based on field investigations and analyses of faulting mechanisms and prevalent stress conditions. The results show that the Beichuan-Yingxiu fault formed a 3.5 km wide restraining stepover at the Xiaoyudong area. The Xiaoyudong fault is not a tear fault suggested by previous researches, but a frontal reverse fault induced by the oblique compression at this stepover; it well accommodates the 'deformation gap' of the Beichuan-Yingxiu fault in the Xiaoyudong area. Further, stress along the Peng-Guan fault plane doubles due to a change in dip angle of the Beichuan-Yingxiu fault across the Xiaoyudong restraining stepover. This resulted in two faults rupturing the ground's surface simultaneously, to the north of the Xiaoyudong area. These results are helpful in deepening our understanding of the dynamic processes that produced surface ruptures during the Wenchuan earthquake. Furthermore, the results suggest more attention be focused on the influence of dextral slip component, the change of the control fault's attitude, and property differences in rocks on either side of faults when discussing the formation mechanism of surface ruptures.

Mechanical Behavior of a Hi-Nicalon(tm)/SiC Composite Having a Polycarbosilane Derived Matrix

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Calomino, Anthony M.; McCue, Terry R.

1999-01-01

Polymer infiltration of a rigidized preform, followed by pyrolysis to convert the polymer to a ceramic, potentially offers a lower cost alternative to CVD. It also offers more moderate temperature requirements than melt infiltration approaches, which should minimize potential fiber damage during processing. However, polymer infiltration and pyrolysis results in a more microcracked matrix. Preliminary mechanical property characterization, including elevated temperature (1204 C) tensile, 500 h stress rupture behavior and low cycle fatigue, was conducted on Hi-Nicalon (TM)/Si-C-(O) composites having a dual layer BN/SiC interface and a matrix derived by impregnation and pyrolysis of allylhydridopolycarbosilane (AHPCS). Microstructural evaluation of failure surfaces and of polished transverse and longitudinal cross sections of the failed specimens was used to identify predominant failure mechanisms. In stress rupture testing at 1093 C, the failure was interface dominated, while at 1204 C in both stress rupture and two hour hold/fatigue tests failure was matrix dominated, resulting in specimen delamination.

Surface rupture and vertical deformation associated with 20 May 2016 M6 Petermann Ranges earthquake, Northern Territory, Australia

NASA Astrophysics Data System (ADS)

Gold, Ryan; Clark, Dan; King, Tamarah; Quigley, Mark

2017-04-01

Surface-rupturing earthquakes in stable continental regions (SCRs) occur infrequently, though when they occur in heavily populated regions the damage and loss of life can be severe (e.g., 2001 Bhuj earthquake). Quantifying the surface-rupture characteristics of these low-probability events is therefore important, both to improve understanding of the on- and off-fault deformation field near the rupture trace and to provide additional constraints on earthquake magnitude to rupture length and displacement, which are critical inputs for seismic hazard calculations. This investigation focuses on the 24 August 2016 M6.0 Petermann Ranges earthquake, Northern Territory, Australia. We use 0.3-0.5 m high-resolution optical Worldview satellite imagery to map the trace of the surface rupture associated with the earthquake. From our mapping, we are able to trace the rupture over a length of 20 km, trending NW, and exhibiting apparent north-side-up motion. To quantify the magnitude of vertical surface deformation, we use stereo Worldview images processed using NASA Ames Stereo Pipeline software to generate pre- and post-earthquake digital terrain models with a spatial resolution of 1.5 to 2 m. The surface scarp is apparent in much of the post-event digital terrain model. Initial efforts to difference the pre- and post-event digital terrain models yield noisy results, though we detect vertical deformation of 0.2 to 0.6 m over length scales of 100 m to 1 km from the mapped trace of the rupture. Ongoing efforts to remove ramps and perform spatial smoothing will improve our understanding of the extent and pattern of vertical deformation. Additionally, we will compare our results with InSAR and field measurements obtained following the earthquake.

Early steps of supported bilayer formation probed by single vesicle fluorescence assays.

PubMed Central

Johnson, Joseph M; Ha, Taekjip; Chu, Steve; Boxer, Steven G

2002-01-01

We have developed a single vesicle assay to study the mechanisms of supported bilayer formation. Fluorescently labeled, unilamellar vesicles (30-100 nm diameter) were first adsorbed to a quartz surface at low enough surface concentrations to visualize single vesicles. Fusion and rupture events during the bilayer formation, induced by the subsequent addition of unlabeled vesicles, were detected by measuring two-color fluorescence signals simultaneously. Lipid-conjugated dyes monitored the membrane fusion while encapsulated dyes reported on the vesicle rupture. Four dominant pathways were observed, each exhibiting characteristic two-color fluorescence signatures: 1) primary fusion, in which an unlabeled vesicle fuses with a labeled vesicle on the surface, is signified by the dequenching of the lipid-conjugated dyes followed by rupture and final merging into the bilayer; 2) simultaneous fusion and rupture, in which a labeled vesicle on the surface ruptures simultaneously upon fusion with an unlabeled vesicle; 3) no dequenching, in which loss of fluorescence signal from both dyes occur simultaneously with the final merger into the bilayer; and 4) isolated rupture (pre-ruptured vesicles), in which a labeled vesicle on the surface spontaneously undergoes content loss, a process that occurs with high efficiency in the presence of a high concentration of Texas Red-labeled lipids. Vesicles that have undergone content loss appear to be more fusogenic than intact vesicles. PMID:12496104

Inherited structures impact on co-seismic surface deformation pattern during the 2013 Balochistan, Pakistan, earthquake

NASA Astrophysics Data System (ADS)

Vallage, Amaury; Klinger, Yann; Grandin, Raphael; Delorme, Arthur; Pierrot-Deseilligny, Marc

2016-04-01

The understanding of earthquake processes and the interaction of earthquake rupture with Earth's free surface relies on the resolution of the observations. Recent and detailed post-earthquake measurements bring new insights on shallow mechanical behavior of rupture processes as it becomes possible to measure and locate surficial deformation distribution. The 2013 Mw 7.7 Balochistan earthquake, Pakistan, offers a nice opportunity to comprehend where and why surficial deformation might differs from at-depth localized slip. This earthquake ruptured the Hoshab fault over 200 km; the motion was mainly left lateral with a small and discontinuous vertical component in the southern part of the rupture. Using images with the finest resolution currently available, we measured the surface displacement amplitude and its orientation at the ground surface (including the numerous tensile cracks). We combined these measurements with the 1:500 scale ground rupture map to focus on the behavior of the frontal rupture in the area where deformation distributes. Comparison with orientations of inherited tectonic structures, visible in older rocks formation surrounding the actual 2013 rupture, shows the control exercised by such structures on co-seismic rupture distribution. Such observation raises the question on how pre-existing tectonic structures in a medium, mapped in several seismically active places around the globe; can control the co-seismic distribution of the deformation during earthquakes.

Evaluating the Possibility of a joint San Andreas-Imperial Fault Rupture in the Salton Trough Region

NASA Astrophysics Data System (ADS)

Kyriakopoulos, C.; Oglesby, D. D.; Meltzner, A. J.; Rockwell, T. K.

2016-12-01

A geodynamic investigation of possible earthquakes in a given region requires both field data and numerical simulations. In particular, the investigation of past earthquakes is also a fundamental part of understanding the earthquake potential of the Salton Trough region. Geological records from paleoseismic trenches inform us of past ruptures (length, magnitude, timing), while dynamic rupture models allow us to evaluate numerically the mechanics of such earthquakes. The two most recent events (Mw 6.4 1940 and Mw 6.9 1979) on the Imperial fault (IF) both ruptured up to the northern end of the mapped fault, giving the impression that rupture doesn't propagate further north. This result is supported by small displacements, 20 cm, measured at the Dogwood site near the end of the mapped rupture in each event. However, 3D paleoseismic data from the same site corresponding to the most recent pre-1940 event (1710 CE) and 5th (1635 CE) and 6th events back revealed up to 1.5 m of slip in those events. Since we expect the surface displacement to decrease toward the termination of a rupture, we postulate that in these earlier cases the rupture propagated further north than in 1940 or 1979. Furthermore, paleoseismic data from the Coachella site (Philibosian et al., 2011) on the San Andreas fault (SAF) indicates slip events ca. 1710 CE and 1588-1662 CE. In other words, the timing of two large paleoseismic displacements on the IF cannot be distinguished from the timing of the two most recent events on the southern SAF, leaving a question: is it possible to have through-going rupture in the Salton Trough? We investigate this question through 3D dynamic finite element rupture modeling. In our work, we considered two scenarios: rupture initiated on the IF propagating northward, and rupture initiated on the SAF propagating southward. Initial results show that, in the first case, rupture propagates north of the mapped northern terminus of the IF only under certain pre-stress conditions, such as values of the seismic parameter S = 0.45 to 2.0, and tends to stop for S = 2.5. If rupture initiates in the north on the SAF, we find that it is easier for it to propagate across the entire stepover region. The results have implications for potential earthquakes in the region, with the possibility of a preferred direction of rupture propagation through the stepover.

Fine structure of the landers fault zone: Segmentation and the rupture process

USGS Publications Warehouse

Li, Y.-G.; Vidale, J.E.; Aki, K.; Marone, C.J.; Lee, W.H.K.

1994-01-01

Observations and modeling of 3- to 6-hertz seismic shear waves trapped within the fault zone of the 1992 Landers earthquake series allow the fine structure and continuity of the zone to be evaluated. The fault, to a depth of at least 12 kilometers, is marked by a zone 100 to 200 meters wide where shear velocity is reduced by 30 to 50 percent. This zone forms a seismic waveguide that extends along the southern 30 kilometers of the Landers rupture surface and ends at the fault bend about 18 kilometers north of the main shock epicenter. Another fault plane waveguide, disconnected from the first, exists along the northern rupture surface. These observations, in conjunction with surface slip, detailed seismicity patterns, and the progression of rupture along the fault, suggest that several simple rupture planes were involved in the Landers earthquake and that the inferred rupture front hesitated or slowed at the location where the rupture jumped from one to the next plane. Reduction in rupture velocity can tentatively be attributed to fault plane complexity, and variations in moment release can be attributed to variations in available energy.

Poro-elastic Rebound Along the Landers 1992 Earthquake Surface Rupture

NASA Technical Reports Server (NTRS)

Peltzer, G.; Rosen, P.; Rogez, F.; Hudnut, K.

1998-01-01

Maps of post-seismic surface displacement after the 1992, Landers, California earthquake, generated by interferometric processing of ERS-1 Synthetic Aperture Radar (SAR) images, reveal effects of various deformation processes near the 1992 surface rupture.

Interactive terrain visualization enables virtual field work during rapid scientific response to the 2010 Haiti earthquake

USGS Publications Warehouse

Cowgill, Eric; Bernardin, Tony S.; Oskin, Michael E.; Bowles, Christopher; Yikilmaz, M. Burak; Kreylos, Oliver; Elliott, Austin J.; Bishop, Scott; Gold, Ryan D.; Morelan, Alexander; Bawden, Gerald W.; Hamann, Bernd; Kellogg, Louise

2012-01-01

The moment magnitude (Mw) 7.0 12 January 2010 Haiti earthquake is the first major earthquake for which a large-footprint LiDAR (light detection and ranging) survey was acquired within several weeks of the event. Here, we describe the use of virtual reality data visualization to analyze massive amounts (67 GB on disk) of multiresolution terrain data during the rapid scientific response to a major natural disaster. In particular, we describe a method for conducting virtual field work using both desktop computers and a 4-sided, 22 m3 CAVE immersive virtual reality environment, along with KeckCAVES (Keck Center for Active Visualization in the Earth Sciences) software tools LiDAR Viewer, to analyze LiDAR point-cloud data, and Crusta, for 2.5 dimensional surficial geologic mapping on a bare-earth digital elevation model. This system enabled virtual field work that yielded remote observations of the topographic expression of active faulting within an ∼75-km-long section of the eastern Enriquillo–Plantain Garden fault spanning the 2010 epicenter. Virtual field observations indicated that the geomorphic evidence of active faulting and ancient surface rupture varies along strike. Landform offsets of 6–50 m along the Enriquillo–Plantain Garden fault east of the 2010 epicenter and closest to Port-au-Prince attest to repeated recent surface-rupturing earthquakes there. In the west, the fault trace is well defined by displaced landforms, but it is not as clear as in the east. The 2010 epicenter is within a transition zone between these sections that extends from Grand Goâve in the west to Fayette in the east. Within this transition, between L'Acul (lat 72°40′W) and the Rouillone River (lat 72°35′W), the Enriquillo–Plantain Garden fault is undefined along an embayed low-relief range front, with little evidence of recent surface rupture. Based on the geometry of the eastern and western faults that show evidence of recent surface rupture, we propose that the 2010 event occurred within a stepover that appears to have served as a long-lived boundary between rupture segments, explaining the lack of 2010 surface rupture. This study demonstrates how virtual reality–based data visualization has the potential to transform rapid scientific response by enabling virtual field studies and real-time interactive analysis of massive terrain data sets.

Surface faulting. A preliminary view

USGS Publications Warehouse

Sharp, R.V.

1989-01-01

This description of surface faulting near Spitak, Armenia, is based on a field inspection made December 22-26, 1988. The surface rupture west of Spitak, displacement of the ground surface, pre-earthquake surface expressions of the fault, and photolineaments in landsat images are described and surface faulting is compared to aftershocks. It is concluded that the 2 meters of maximum surface displacement fits well within the range of reliably measured maximum surface offsets for historic reverse and oblique-reverse faulting events throughout the world. By contrast, the presently known length of surface rupture near Spitak, between 8 and 13 km, is shorter than any other reverse or oblique-reverse event of magnitude greater than 6.0. This may be a reason to suppose that additional surface rupture might remain unmapped.

Investigation of the 27 February 2010 Mw 8.8 Chilean earthquake integrating aftershock analysis, back-projection imaging and cGPS results

NASA Astrophysics Data System (ADS)

Clévédé, E.; Satriano, C.; Bukchin, B.; Lancieri, M.; Fuenzalida, A.; Vilotte, J.; Lyon-Caen, H.; Vigny, C.; Socquet, A.; Aranda, C.; Campos, J. A.; Scientific Team of the Lia Montessus de Ballore (Cnrs-Insu, U. Chile)

2010-12-01

The Mw 8.8 earthquake in central Chile ruptured more than 400 km along the subduction bound between the Nazca and the South American plates. The aftershock distribution clearly shows that this earthquake filled a well-known seismic gap, corresponding to rupture extension of the 1835 earthquake. The triggered post-seismic activity extends farther north of the gap, partially overlapping the 1985 and the 1960 Valparaiso earthquakes. However, the analysis of continuous GPS (cGPS) recordings, and back projection imaging of teleseismic body wave energy, indicate that the rupture stopped south of Valparaiso, around -33.5 degrees of latitude. An important question is how far the rupture actually extended to the north and the potential relation between the northernmost aftershock activity and remaining asperities within the ruptured zone of the previous Valparaiso earthquakes. The extension of the rupture offshore, towards west, also deserves further investigation. The aftershock distribution and the back propagation analysis support the hypothesis that, in the northern part, the rupture may have reached the surface at the trench. In this work, we performed a CMT and depth location study for more than 10 of the immediate largest aftershocks using teleseismic surface wave analysis constrained by P-wave polarity. In parallel, a detailed analysis of aftershocks in the northern part of the rupture, between 2010-03-11 and 2010-05-13, have been performed using the data from the station of the Chilean Servicio Sismológico Nacional (SSN), and of the post-seismic network, deployed by the French CNRS-INSU, GFZ, IRIS, and Caltech. We accurately hand-picked 153 larger events, which have been located using a non-linear probabilistic code, with improved depth location. Focal mechanisms have been computed for the larger events. Those results have been integrated with the analysis of cGPS and teleseismic back projection, and the overall kinematic of the Maule earthquake is discussed as well as the extension of the rupture along strike and dip.

Spontaneous subserosal venous rupture overlying a uterine leiomyoma in a young woman.

PubMed

Jenayah, Amel Achour; Saoudi, Sarah; Sferi, Nour; Skander, Rim; Marzouk, Sofiène Ben; Cherni, Abdallah; Sfar, Ezzeddine; Chelli, Dalenda; Boudaya, Fethia

2017-01-01

Uterine leiomyomas are very common tumors found in women. Rupture of veins on the surface of uterine leiomyoma is an unusual source of hemoperitoneum. It is an extremely uncommon gynaecological cause of hemoperitoneum. It is a life threatening emergency. We report a case of massive intraperitoneal hemorrhage due to rupture of vessels on the surface of subserous leiomyoma. A differential diagnosis of rupture of leiomyoma'ssurface vessel should be considered, while dealing with a case of hemoperitoneum with pelvic mass.

Investigation of possibility of surface rupture derived from PFDHA and calculation of surface displacement based on dislocation

NASA Astrophysics Data System (ADS)

Inoue, N.; Kitada, N.; Irikura, K.

2013-12-01

A probability of surface rupture is important to configure the seismic source, such as area sources or fault models, for a seismic hazard evaluation. In Japan, Takemura (1998) estimated the probability based on the historical earthquake data. Kagawa et al. (2004) evaluated the probability based on a numerical simulation of surface displacements. The estimated probability indicates a sigmoid curve and increases between Mj (the local magnitude defined and calculated by Japan Meteorological Agency) =6.5 and Mj=7.0. The probability of surface rupture is also used in a probabilistic fault displacement analysis (PFDHA). The probability is determined from the collected earthquake catalog, which were classified into two categories: with surface rupture or without surface rupture. The logistic regression is performed for the classified earthquake data. Youngs et al. (2003), Ross and Moss (2011) and Petersen et al. (2011) indicate the logistic curves of the probability of surface rupture by normal, reverse and strike-slip faults, respectively. Takao et al. (2013) shows the logistic curve derived from only Japanese earthquake data. The Japanese probability curve shows the sharply increasing in narrow magnitude range by comparison with other curves. In this study, we estimated the probability of surface rupture applying the logistic analysis to the surface displacement derived from a surface displacement calculation. A source fault was defined in according to the procedure of Kagawa et al. (2004), which determined a seismic moment from a magnitude and estimated the area size of the asperity and the amount of slip. Strike slip and reverse faults were considered as source faults. We applied Wang et al. (2003) for calculations. The surface displacements with defined source faults were calculated by varying the depth of the fault. A threshold value as 5cm of surface displacement was used to evaluate whether a surface rupture reach or do not reach to the surface. We carried out the logistic regression analysis to the calculated displacements, which were classified by the above threshold. The estimated probability curve indicated the similar trend to the result of Takao et al. (2013). The probability of revere faults is larger than that of strike slip faults. On the other hand, PFDHA results show different trends. The probability of reverse faults at higher magnitude is lower than that of strike slip and normal faults. Ross and Moss (2011) suggested that the sediment and/or rock over the fault compress and not reach the displacement to the surface enough. The numerical theory applied in this study cannot deal with a complex initial situation such as topography.

Rupture dynamics along dipping thrust faults: free surface interaction and the case of Tohoku earthquake

NASA Astrophysics Data System (ADS)

Festa, Gaetano; Scala, Antonio; Vilotte, Jean-Pierre

2017-04-01

To address the influence of the free surface interaction on rupture propagating along subduction zones, we numerically investigate dynamic interactions, involving coupling between normal and shear tractions, between in-plane rupture propagating along dipping thrust faults and a free surface for different structural and geometrical conditions. When the rupture occurs along reverse fault with a dip angle different from 90° the symmetry is broken as an effect of slip-induced normal stress perturbations and a larger ground motion is evidenced on the hanging wall. The ground motion is amplified by multiple reflections of waves trapped between the fault and the free surface. This effect is shown to occur when the rupture tip lies on the vertical below the intersection between the S-wave front and the surface that is when waves along the surface start to interact with the rupture front. This interaction is associated with a finite region where the rupture advances in a massive regime preventing the shrinking of the process zone and the emission of high-frequency radiation. The smaller the dip angle the larger co-seismic slip in the shallow part as an effect of the significant break of symmetry. Radiation from shallow part is still depleted in high frequencies due to the massive propagating regime and the interaction length dominating the rupture dynamics. Instantaneous shear response to normal traction perturbations may lead to unstable solutions as in the case of bimaterial rupture. A parametric study has been performed to analyse the effects of a regularised shear traction response to normal traction variations. Finally the case of Tohoku earthquake is considered and we present 2D along-dip numerical results. At first order the larger slip close to the trench can be ascribed to the break of symmetry and the interaction with free surface. When shear/normal coupling is properly regularised the signal from the trench is depleted in high frequencies whereas during deep propagation high-frequency radiations emerge associated to geometrical and structural complexities or to frictional strength asperities.

3D Dynamic Rupture Simulations along Dipping Faults, with a focus on the Wasatch Fault Zone, Utah

NASA Astrophysics Data System (ADS)

Withers, K.; Moschetti, M. P.

2017-12-01

We study dynamic rupture and ground motion from dip-slip faults in regions that have high-seismic hazard, such as the Wasatch fault zone, Utah. Previous numerical simulations have modeled deterministic ground motion along segments of this fault in the heavily populated regions near Salt Lake City but were restricted to low frequencies ( 1 Hz). We seek to better understand the rupture process and assess broadband ground motions and variability from the Wasatch Fault Zone by extending deterministic ground motion prediction to higher frequencies (up to 5 Hz). We perform simulations along a dipping normal fault (40 x 20 km along strike and width, respectively) with characteristics derived from geologic observations to generate a suite of ruptures > Mw 6.5. This approach utilizes dynamic simulations (fully physics-based models, where the initial stress drop and friction law are imposed) using a summation by parts (SBP) method. The simulations include rough-fault topography following a self-similar fractal distribution (over length scales from 100 m to the size of the fault) in addition to off-fault plasticity. Energy losses from heat and other mechanisms, modeled as anelastic attenuation, are also included, as well as free-surface topography, which can significantly affect ground motion patterns. We compare the effect of material structure and both rate and state and slip-weakening friction laws have on rupture propagation. The simulations show reduced slip and moment release in the near surface with the inclusion of plasticity, better agreeing with observations of shallow slip deficit. Long-wavelength fault geometry imparts a non-uniform stress distribution along both dip and strike, influencing the preferred rupture direction and hypocenter location, potentially important for seismic hazard estimation.

Paleoearthquakes and Eolian-dominated fault sedimentation along the Hubbell Spring fault zone near Albuquerque, New Mexico

USGS Publications Warehouse

Personius, S.F.; Mahan, S.A.

2003-01-01

The Hubbell Spring fault zone forms the modern eastern margin of the Rio Grande rift in the Albuquerque basin of north-central New Mexico. Knowledge of its seismic potential is important because the fault zone transects Kirtland Air Force Base/Sandia National Laboratories and underlies the southern Albuquerque metropolitan area. No earthquakes larger than ML 5.5 have been reported in the last 150 years in this region, so we excavated the first trench across this fault zone to determine its late Quaternary paleoseismic history. Our trench excavations revealed a complex, 16-m-wide fault zone overlain by four tapered blankets of mixed eolian sand and minor colluvium that we infer were deposited after four large-magnitude, surface-rupturing earthquakes. Although the first (oldest) rupture event is undated, we used luminescence (thermoluminescence and infrared-stimulated luminescence) ages to determine that the subsequent three rupture events occurred about 56 ?? 6, 29 ?? 3, and 12 ?? 1 ka. These ages yield recurrence intervals of 27 and 17 k.y. between events and an elapsed time of 12 k.y. since the latest surface-rupturing paleoearthquake. Slip rates are not well constrained, but our preferred average slip rate since rupture event 2 (post-56 ka) is 0.05 mm/yr, and interval slip rates between the last three events are 0.06 and 0.09 mm/yr, respectively. Vertical displacements of 1-2 m per event and probable rupture lengths of 34-43 km indicate probable paleoearthquake magnitudes (Ms or Mw) of 6.8-7.1. Future earthquakes of this size likely would cause strong ground motions in the Albuquerque metropolitan area.

Propose a Wall Shear Stress Divergence to Estimate the Risks of Intracranial Aneurysm Rupture

PubMed Central

Zhang, Y.; Takao, H.; Murayama, Y.; Qian, Y.

2013-01-01

Although wall shear stress (WSS) has long been considered a critical indicator of intracranial aneurysm rupture, there is still no definite conclusion as to whether a high or a low WSS results in aneurysm rupture. The reason may be that the effect of WSS direction has not been fully considered. The objectives of this study are to investigate the magnitude of WSS (|WSS|) and its divergence on the aneurysm surface and to test the significance of both in relation to the aneurysm rupture. Patient-specific computational fluid dynamics (CFD) was used to compute WSS and wall shear stress divergence (WSSD) on the aneurysm surface for nineteen patients. Our results revealed that if high |WSS| is stretching aneurysm luminal surface, and the stretching region is concentrated, the aneurysm is under a high risk of rupture. It seems that, by considering both direction and magnitude of WSS, WSSD may be a better indicator for the risk estimation of aneurysm rupture (154). PMID:24191140

Preliminary Study on Earthquake Surface Rupture Extraction from Uav Images

NASA Astrophysics Data System (ADS)

Yuan, X.; Wang, X.; Ding, X.; Wu, X.; Dou, A.; Wang, S.

2018-04-01

Because of the advantages of low-cost, lightweight and photography under the cloud, UAVs have been widely used in the field of seismic geomorphology research in recent years. Earthquake surface rupture is a typical seismic tectonic geomorphology that reflects the dynamic and kinematic characteristics of crustal movement. The quick identification of earthquake surface rupture is of great significance for understanding the mechanism of earthquake occurrence, disasters distribution and scale. Using integrated differential UAV platform, series images were acquired with accuracy POS around the former urban area (Qushan town) of Beichuan County as the area stricken seriously by the 2008 Wenchuan Ms8.0 earthquake. Based on the multi-view 3D reconstruction technique, the high resolution DSM and DOM are obtained from differential UAV images. Through the shade-relief map and aspect map derived from DSM, the earthquake surface rupture is extracted and analyzed. The results show that the surface rupture can still be identified by using the UAV images although the time of earthquake elapse is longer, whose middle segment is characterized by vertical movement caused by compression deformation from fault planes.

Constant Stress Drop Fits Earthquake Surface Slip-Length Data

NASA Astrophysics Data System (ADS)

Shaw, B. E.

2011-12-01

Slip at the surface of the Earth provides a direct window into the earthquake source. A longstanding controversy surrounds the scaling of average surface slip with rupture length, which shows the puzzling feature of continuing to increase with rupture length for lengths many times the seismogenic width. Here we show that a more careful treatment of how ruptures transition from small circular ruptures to large rectangular ruptures combined with an assumption of constant stress drop provides a new scaling law for slip versus length which (1) does an excellent job fitting the data, (2) gives an explanation for the large crossover lengthscale at which slip begins to saturate, and (3) supports constant stress drop scaling which matches that seen for small earthquakes. We additionally discuss how the new scaling can be usefully applied to seismic hazard estimates.

Surface and Subsurface Fault Displacements from the September 2010 Darfield (Canterbury) Earthquake

NASA Astrophysics Data System (ADS)

Meyers, B.; Furlong, K. P.; Hayes, G. P.; Herman, M. W.; Quigley, M.

2012-12-01

On September 3, 2010 a Magnitude 7.1 earthquake struck near Darfield, New Zealand. This was to be the first earthquake in an ongoing, damaging sequence near the city of Christchurch. The earthquake produced a surface rupture with measurable offsets of up to 5.3m along a 30km surface fault system. The spatial pattern of slip during this rupture has been determined by various groups using a range of approaches and several independent data sets. Surface fault rupture was measured in the field and fault slip at depth has been inferred from a seismologic finite fault model (FFM) and various geodetic observations including GPS and InSAR. Here we compare the observed segmented surface displacements with fault slip inferred from the other data. Measurements of the surface rupture show segmented faulting consistent with subsurface slip in the FFM. In the FFM, the main slip patch near the hypocenter can be directly correlated to the region of maximum surface displacement. The FFM and some evidence in the InSAR data also indicate that the Greendale fault system, the structure responsible for the bulk of the rupture, continues at depth closer towards Christchurch than is seen in surface rupture patterns. There is an additional 20km long patch with up to 3m of modeled slip seen in the eastern end of the inverted fault, offset to the south from the Greendale fault trace. This additional fault segment is consistent with a zone of aftershock activity of the main Darfield event, and with local patterns of strong motion. It thus appears that slip recorded at the surface does not describe the entire fault system. This eastward extension of the September rupture means that there is only a short segment of unruptured crust remaining along the entire fault system involved in the Canterbury earthquake sequence.

Ball-and-socket tectonic rotation during the 2013 Mw 7.7 Balochistan earthquake

NASA Astrophysics Data System (ADS)

Barnhart, W. D.; Hayes, G. P.; Briggs, R. W.; Gold, R. D.; Bilham, R.

2014-10-01

The September 2013 Mw 7.7 Balochistan earthquake ruptured a ∼200-km-long segment of the curved Hoshab fault in southern Pakistan with 10 ± 0.2 m of peak sinistral and ∼ 1.7 ± 0.8 m of dip slip. This rupture is unusual because the fault dips 60 ± 15° towards the focus of a small circle centered in northwest Pakistan, and, despite a 30° increase in obliquity along strike, the ratios of strike and dip slip remain relatively uniform. Surface displacements and geodetic and teleseismic source inversions quantify a bilateral rupture that propagated rapidly at shallow depths from a transtensional jog near the northern end of the rupture. Static friction prior to rupture was unusually weak (μ < 0.05), and friction may have approached zero during dynamic rupture. Here we show that the inward-dipping Hoshab fault defines the northern rim of a structural unit in southeast Makran that rotates - akin to a 2-D ball-and-socket joint - counter-clockwise in response to India's penetration into the Eurasian plate. This rotation accounts for complexity in the Chaman fault system and, in principle, reduces seismic potential near Karachi; nonetheless, these findings highlight deficiencies in strong ground motion equations and tectonic models that invoke Anderson-Byerlee faulting predictions.

Ball-and-socket tectonic rotation during the 2013 Mw7.7 Balochistan earthquake

USGS Publications Warehouse

Barnhart, William D.; Hayes, Gavin P.; Briggs, Richard W.; Gold, Ryan D.; Bilham, R.

2014-01-01

The September 2013 Mw7.7 Balochistan earthquake ruptured a ∼200-km-long segment of the curved Hoshab fault in southern Pakistan with 10±0.2 m of peak sinistral and ∼1.7±0.8 m of dip slip. This rupture is unusual because the fault dips 60±15° towards the focus of a small circle centered in northwest Pakistan, and, despite a 30° increase in obliquity along strike, the ratios of strike and dip slip remain relatively uniform. Surface displacements and geodetic and teleseismic source inversions quantify a bilateral rupture that propagated rapidly at shallow depths from a transtensional jog near the northern end of the rupture. Static friction prior to rupture was unusually weak (μ<0.05), and friction may have approached zero during dynamic rupture. Here we show that the inward-dipping Hoshab fault defines the northern rim of a structural unit in southeast Makran that rotates – akin to a 2-D ball-and-socket joint – counter-clockwise in response to India's penetration into the Eurasian plate. This rotation accounts for complexity in the Chaman fault system and, in principle, reduces seismic potential near Karachi; nonetheless, these findings highlight deficiencies in strong ground motion equations and tectonic models that invoke Anderson–Byerlee faulting predictions.

3D fault curvature and fractal roughness: Insights for rupture dynamics and ground motions using a Discontinous Galerkin method

NASA Astrophysics Data System (ADS)

Ulrich, Thomas; Gabriel, Alice-Agnes

2017-04-01

Natural fault geometries are subject to a large degree of uncertainty. Their geometrical structure is not directly observable and may only be inferred from surface traces, or geophysical measurements. Most studies aiming at assessing the potential seismic hazard of natural faults rely on idealised shaped models, based on observable large-scale features. Yet, real faults are wavy at all scales, their geometric features presenting similar statistical properties from the micro to the regional scale. Dynamic rupture simulations aim to capture the observed complexity of earthquake sources and ground-motions. From a numerical point of view, incorporating rough faults in such simulations is challenging - it requires optimised codes able to run efficiently on high-performance computers and simultaneously handle complex geometries. Physics-based rupture dynamics hosted by rough faults appear to be much closer to source models inverted from observation in terms of complexity. Moreover, the simulated ground-motions present many similarities with observed ground-motions records. Thus, such simulations may foster our understanding of earthquake source processes, and help deriving more accurate seismic hazard estimates. In this presentation, the software package SeisSol (www.seissol.org), based on an ADER-Discontinuous Galerkin scheme, is used to solve the spontaneous dynamic earthquake rupture problem. The usage of tetrahedral unstructured meshes naturally allows for complicated fault geometries. However, SeisSol's high-order discretisation in time and space is not particularly suited for small-scale fault roughness. We will demonstrate modelling conditions under which SeisSol resolves rupture dynamics on rough faults accurately. The strong impact of the geometric gradient of the fault surface on the rupture process is then shown in 3D simulations. Following, the benefits of explicitly modelling fault curvature and roughness, in distinction to prescribing heterogeneous initial stress conditions on a planar fault, is demonstrated. Furthermore, we show that rupture extend, rupture front coherency and rupture speed are highly dependent on the initial amplitude of stress acting on the fault, defined by the normalized prestress factor R, the ratio of the potential stress drop over the breakdown stress drop. The effects of fault complexity are particularly pronounced for lower R. By low-pass filtering a rough fault at several cut-off wavelengths, we then try to capture rupture complexity using a simplified fault geometry. We find that equivalent source dynamics can only be obtained using a scarcely filtered fault associated with a reduced stress level. To investigate the wavelength-dependent roughness effect, the fault geometry is bandpass-filtered over several spectral ranges. We show that geometric fluctuations cause rupture velocity fluctuations of similar length scale. The impact of fault geometry is especially pronounced when the rupture front velocity is near supershear. Roughness fluctuations significantly smaller than the rupture front characteristic dimension (cohesive zone size) affect only macroscopic rupture properties, thus, posing a minimum length scale limiting the required resolution of 3D fault complexity. Lastly, the effect of fault curvature and roughness on the simulated ground-motions is assessed. Despite employing a simple linear slip weakening friction law, the simulated ground-motions compare well with estimates from ground motions prediction equations, even at relatively high frequencies.

Seismic Evidence of A Widely Distributed West Napa Fault Zone, Hendry Winery, Napa, California

NASA Astrophysics Data System (ADS)

Goldman, M.; Catchings, R.; Chan, J. H.; Criley, C.

2015-12-01

Following the 24 August 2014 Mw 6.0 South Napa earthquake, surface rupture was mapped along the West Napa Fault Zone (WNFZ) for a distance of ~ 14 km and locally within zones up to ~ 2 km wide. Near the northern end of the surface rupture, however, several strands coalesced to form a narrow, ~100-m-wide zone of surface rupture. To determine the location, width, and shallow (upper few hundred meters) geometry of the fault zone, we acquired an active-source seismic survey across the northern surface rupture in February 2015. We acquired both P- and S-wave data, from which we developed reflection images and tomographic images of Vp, Vs, Vp/Vs, and Poisson's ratio of the upper 100 m. We also used small explosive charges within surface ruptures located ~600 m north of our seismic array to record fault-zone guided waves. Our data indicate that at the latitude of the Hendry Winery, the WNFZ is characterized by at least five fault traces that are spaced 60 to 200 m apart. Zones of low-Vs, low-Vp/Vs, and disrupted reflectors highlight the fault traces on the tomography and reflection images. On peak-ground-velocity (PGV) plots, the most pronounced high-amplitude guided-wave seismic energy coincides precisely with the mapped surface ruptures, and the guided waves also show discrete high PGV zones associated with unmapped fault traces east of the surface ruptures. Although the surface ruptures of the WNFZ were observed only over a 100-m-wide zone at the Hendry Winery, our data indicate that the fault zone is at least 400 m wide, which is probably a minimum width given the 400-m length of our seismic profile. Slip on the WNFZ is generally considered to be low relative to most other Bay Area faults, but we suggest that the West Napa Fault is a zone of widely distributed shear, and to fully account for the total slip on the WNFZ, slip on all traces of this wide fault zone must be considered.

Explosive-driven, high speed, arcless switch

DOEpatents

Skogmo, P.J.; Tucker, T.J.

1986-05-02

An explosive-actuated, fast-acting arcless switch contains a highly conductive foil to carry high currents positioned adjacent a dielectric surface within a casing. At one side of the foil opposite the dielectric surface is an explosive which, when detonated, drives the conductive foil against the dielectric surface. A pattern of grooves in the dielectric surface ruptures the foil to establish a rupture path having a pattern corresponding to the pattern of the grooves. The impedance of the ruptured foil is greater than that of the original foil to divert high current to a load. Planar and cylindrical embodiments of the switch are disclosed.

Explosive-driven, high speed, arcless switch

DOEpatents

Skogmo, Phillip J.; Tucker, Tillman J.

1987-01-01

An explosive-actuated, fast-acting arcless switch contains a highly conductive foil to carry high currents positioned adjacent a dielectric surface within a casing. At one side of the foil opposite the dielectric surface is an explosive which, when detonated, drives the conductive foil against the dielectric surface. A pattern of grooves in the dielectric surface ruptures the foil to establish a rupture path having a pattern corresponding to the pattern of the grooves. The impedance of the ruptured foil is greater than that of the original foil to divert high current to a load. Planar and cylindrical embodiments of the switch are disclosed.

Fault Branching and Long-Term Earthquake Rupture Scenario for Strike-Slip Earthquake

NASA Astrophysics Data System (ADS)

Klinger, Y.; CHOI, J. H.; Vallage, A.

2017-12-01

Careful examination of surface rupture for large continental strike-slip earthquakes reveals that for the majority of earthquakes, at least one major branch is involved in the rupture pattern. Often, branching might be either related to the location of the epicenter or located toward the end of the rupture, and possibly related to the stopping of the rupture. In this work, we examine large continental earthquakes that show significant branches at different scales and for which ground surface rupture has been mapped in great details. In each case, rupture conditions are described, including dynamic parameters, past earthquakes history, and regional stress orientation, to see if the dynamic stress field would a priori favor branching. In one case we show that rupture propagation and branching are directly impacted by preexisting geological structures. These structures serve as pathways for the rupture attempting to propagate out of its shear plane. At larger scale, we show that in some cases, rupturing a branch might be systematic, hampering possibilities for the development of a larger seismic rupture. Long-term geomorphology hints at the existence of a strong asperity in the zone where the rupture branched off the main fault. There, no evidence of throughgoing rupture could be seen along the main fault, while the branch is well connected to the main fault. This set of observations suggests that for specific configurations, some rupture scenarios involving systematic branching are more likely than others.

Three-dimensional curved grid finite-difference modelling for non-planar rupture dynamics

NASA Astrophysics Data System (ADS)

Zhang, Zhenguo; Zhang, Wei; Chen, Xiaofei

2014-11-01

In this study, we present a new method for simulating the 3-D dynamic rupture process occurring on a non-planar fault. The method is based on the curved-grid finite-difference method (CG-FDM) proposed by Zhang & Chen and Zhang et al. to simulate the propagation of seismic waves in media with arbitrary irregular surface topography. While keeping the advantages of conventional FDM, that is computational efficiency and easy implementation, the CG-FDM also is flexible in modelling the complex fault model by using general curvilinear grids, and thus is able to model the rupture dynamics of a fault with complex geometry, such as oblique dipping fault, non-planar fault, fault with step-over, fault branching, even if irregular topography exists. The accuracy and robustness of this new method have been validated by comparing with the previous results of Day et al., and benchmarks for rupture dynamics simulations. Finally, two simulations of rupture dynamics with complex fault geometry, that is a non-planar fault and a fault rupturing a free surface with topography, are presented. A very interesting phenomenon was observed that topography can weaken the tendency for supershear transition to occur when rupture breaks out at a free surface. Undoubtedly, this new method provides an effective, at least an alternative, tool to simulate the rupture dynamics of a complex non-planar fault, and can be applied to model the rupture dynamics of a real earthquake with complex geometry.

Rupture processes of the 2010 Canterbury earthquake and the 2011 Christchurch earthquake inferred from InSAR, strong motion and teleseismic datasets

NASA Astrophysics Data System (ADS)

Yun, S.; Koketsu, K.; Aoki, Y.

2014-12-01

The September 4, 2010, Canterbury earthquake with a moment magnitude (Mw) of 7.1 is a crustal earthquake in the South Island, New Zealand. The February 22, 2011, Christchurch earthquake (Mw=6.3) is the biggest aftershock of the 2010 Canterbury earthquake that is located at about 50 km to the east of the mainshock. Both earthquakes occurred on previously unrecognized faults. Field observations indicate that the rupture of the 2010 Canterbury earthquake reached the surface; the surface rupture with a length of about 30 km is located about 4 km south of the epicenter. Also various data including the aftershock distribution and strong motion seismograms suggest a very complex rupture process. For these reasons it is useful to investigate the complex rupture process using multiple data with various sensitivities to the rupture process. While previously published source models are based on one or two datasets, here we infer the rupture process with three datasets, InSAR, strong-motion, and teleseismic data. We first performed point source inversions to derive the focal mechanism of the 2010 Canterbury earthquake. Based on the focal mechanism, the aftershock distribution, the surface fault traces and the SAR interferograms, we assigned several source faults. We then performed the joint inversion to determine the rupture process of the 2010 Canterbury earthquake most suitable for reproducing all the datasets. The obtained slip distribution is in good agreement with the surface fault traces. We also performed similar inversions to reveal the rupture process of the 2011 Christchurch earthquake. Our result indicates steep dip and large up-dip slip. This reveals the observed large vertical ground motion around the source region is due to the rupture process, rather than the local subsurface structure. To investigate the effects of the 3-D velocity structure on characteristic strong motion seismograms of the two earthquakes, we plan to perform the inversion taking 3-D velocity structure of this region into account.

Crystal plastic earthquakes in dolostones: from slow to fast ruptures.

NASA Astrophysics Data System (ADS)

Passelegue, F. X.; Aubry, J.; Nicolas, A.; Fondriest, M.; Schubnel, A.; Di Toro, G.

2017-12-01

Dolostone is the most dominant lithology of the seismogenic upper crust around the Mediterranean Sea. Understanding the internal mechanisms controlling fault friction is crucial for understanding seismicity along active faults. Displacement in such fault zones is frequently highlighted by highly reflective (mirror-like) slip surfaces, created by thin films of nanogranular fault rock. Using saw-cut dolostone samples coming from natural fault zones, we conducted stick-slip experiments under triaxial loading conditions at 30, 60 and 90 MPa confining pressure and temperature ranging from 30 to 100 degrees C. At 30 and 65 degrees C, only slow rupture was observed and the experimental fault exhibits frictional behaviour, i.e. a dependence of normal stress on peak shear stress. At 65 degrees C, a strengthening behaviour is observed after the main rupture, leading to a succession of slow rupture. At 100 degrees C, the macroscopic behaviour of the fault becomes ductile, and no dependence of pressure on the peak shear stress is observed. In addition, the increase of the confining pressure up to 60 and 90 MPa allow the transition from slow to fast rupture, highlighted by the records of acoustic activity and by dynamic stress drop occurring in a few tens of microseconds. Using strain gages located along the fault surface and acoustic transducers, we were able to measure the rupture velocities during slow and fast rupture. Slow ruptures propagated around 0.1 m/s, in agreement with natural observations. Fast ruptures propagated up to supershear velocities, i.e. faster than the shear wave speed (>3500 m/s). A complete study of the microstructures was realized before and after ruptures. Slow ruptures lead to the production of mirror-like surface driven by the production of nanograins due to dislocation processes. Fast ruptures induce the production of amorphous material along the fault surface, which may come from decarbonation and melting processes. We demonstrate that the transition from slow to fast instabilities is observed due to an increase of the fault stiffness with increasing both temperature and confining pressure. This increase in the stiffness leads to an increase of the slip velocity during the main instability, which allow flash weakening processes and fast propagation of the seismic rupture.

Surface Rupture and Slip Distribution Resulting from the 2013 M7.7 Balochistan, Pakistan Earthquake

NASA Astrophysics Data System (ADS)

Reitman, N. G.; Gold, R. D.; Briggs, R. W.; Barnhart, W. D.; Hayes, G. P.

2014-12-01

The 24 September 2013 M7.7 earthquake in Balochistan, Pakistan, produced a ~200 km long left-lateral strike-slip surface rupture along a portion of the Hoshab fault, a moderately dipping (45-75º) structure in the Makran accretionary prism. The rupture is remarkably continuous and crosses only two (0.7 and 1.5 km wide) step-overs along its arcuate path through southern Pakistan. Displacements are dominantly strike-slip, with a minor component of reverse motion. We remotely mapped the surface rupture at 1:5,000 scale and measured displacements using high resolution (0.5 m) pre- and post-event satellite imagery. We mapped 295 laterally faulted stream channels, terrace margins, and roads to quantify near-field displacement proximal (±10 m) to the rupture trace. The maximum near-field left-lateral offset is 15±2 m (average of ~7 m). Additionally, we used pre-event imagery to digitize 254 unique landforms in the "medium-field" (~100-200 m from the rupture) and then measured their displacements compared to the post-event imagery. At this scale, maximum left-lateral offset approaches 17 m (average of ~8.5 m). The width (extent of observed surface faulting) of the rupture zone varies from ~1 m to 3.7 km. Near- and medium-field offsets show similar slip distributions that are inversely correlated with the width of the fault zone at the surface (larger offsets correspond to narrow fault zones). The medium-field offset is usually greater than the near-field offset. The along-strike surface slip distribution is highly variable, similar to the slip distributions documented for the 2002 Denali M7.9 earthquake and 2001 Kunlun M7.8 earthquake, although the Pakistan offsets are larger in magnitude. The 2013 Pakistan earthquake ranks among the largest documented continental strike-slip displacements, possibly second only to the 18+ m surface displacements attributed to the 1855 Wairarapa M~8.1 earthquake.

Explosive-driven, high speed, arcless switch

DOEpatents

Skogmo, P.J.; Tucker, T.J.

1987-07-14

An explosive-actuated, fast-acting arcless switch contains a highly conductive foil to carry high currents positioned adjacent a dielectric surface within a casing. At one side of the foil opposite the dielectric surface is an explosive which, when detonated, drives the conductive foil against the dielectric surface. A pattern of grooves in the dielectric surface ruptures the foil to establish a rupture path having a pattern corresponding to the pattern of the grooves. The impedance of the ruptured foil is greater than that of the original foil to divert high current to a load. Planar and cylindrical embodiments of the switch are disclosed. 7 figs.

Rupture history of 2008 May 12 Mw 8.0 Wen-Chuan earthquake: Evidence of slip interaction

NASA Astrophysics Data System (ADS)

Ji, C.; Shao, G.; Lu, Z.; Hudnut, K.; Jiu, J.; Hayes, G.; Zeng, Y.

2008-12-01

We will present the rupture process of the May 12, 2008 Mw 8.0 Wenchuan earthquake using all available data. The current model, using both teleseismic body and surface waves and interferometric LOS displacements, reveals an unprecedented complex rupture process which can not be resolved using either of the datasets individually. Rupture of this earthquake involved both the low angle Pengguan fault and the high angle Beichuan fault, which intersect each other at depth and are separated approximately 5-15 km at the surface. Rupture initiated on the Pengguan fault and triggered rupture on the Beichuan fault 10 sec later. The two faults dynamically interacted and unilaterally ruptured over 270 km with an average rupture velocity of 3.0 km/sec. The total seismic moment is 1.1x1021 Nm (Mw 8.0), roughly equally partitioned between the two faults. However, the spatiotemporal evaluations of the two faults are very different. This study will focus on the evidence for fault interactions and will analyze the corresponding uncertainties, in preparation for future dynamic studies of the same detailed nature.

Scale-Dependent Friction and Damage Interface law: implications for effective earthquake rupture dynamics and radiation

NASA Astrophysics Data System (ADS)

Festa, Gaetano; Vilotte, Jean-Pierre; Raous, Michel; Henninger, Carole

2010-05-01

Propagation and radiation of an earthquake rupture is commonly considered as a friction dominated process on fault surfaces. Friction laws, such as the slip weakening and the rate-and-state laws are widely used in the modeling of the earthquake rupture process. These laws prescribe the traction evolution versus slip, slip rate and potentially other internal variables. They introduce a finite cohesive length scale over which the fracture energy is released. However faults are finite-width interfaces with complex internal structures, characterized by highly damaged zones embedding a very thin principal slip interface where most of the dynamic slip localizes. Even though the rupture process is generally investigated at wavelengths larger than the fault zone thickness, which should justify a formulation based upon surface energy, a consistent homogeneization, a very challenging problem, is still missing. Such homogeneization is however be required to derive the consistent form of an effective interface law, as well as the appropriate physical variables and length scales, to correctly describe the coarse-grained dissipation resulting from surface and volumetric contributions at the scale of the fault zone. In this study, we investigate a scale-dependent law, introduced by Raous et al. (1999) in the context of adhesive material interfaces, that takes into account the transition between a damage dominated and a friction dominated state. Such a phase-field formalism describes this transition through an order parameter. We first compare this law to standard slip weakening friction law in terms of the rupture nucleation. The problem is analyzed through the representation of the solution of the quasi-static elastic problem onto the Chebyshev polynomial basis, generalizing the Uenishi-Rice solution. The nucleation solutions, at the onset of instability, are then introduced as initial conditions for the study of the dynamic rupture propagation, in the case of in-plane rupture, using high-order Spectral Element Methods and non-smooth contact mechanics. In particular, we investigate the implications of this new interface law in terms of the rupture propagation and arrest. Special attention is focused on radiation and supershear transition. Comparison with the classical slip weakening friction law is provided. Finally, first results toward a dynamic consistent homogeneization of damaged fault zones will be discussed. Raous, M., Cangémi, L. and Cocou, M. (1999). A consistent model coupling adhesion, friction and unilateral contact', Computer Methods in Applied Mechanics and Engineering, Vol. 177, pp.383-399.

Crystal plastic earthquakes in dolostones

NASA Astrophysics Data System (ADS)

Passelegue, Francois; Aubry, Jerome; Nicolas, Aurelien; Fondriest, Michele; Schubnel, Alexandre; Di Toro, Giulio

2017-04-01

Dolostone is the most dominant lithology of the seismogenic upper crust around the Mediterranean Sea. Understanding the internal mechanisms controlling fault friction is crucial for understanding seismicity along active faults. Displacement in such fault zones is frequently highlighted by highly reflective (mirror-like) slip surfaces, created by thin films of nanogranular fault rock. Using saw-cut dolostone samples coming from natural fault zones, we conducted friction experiments under triaxial loading conditions. To reproduce the natural conditions, experiments were conducted at 30, 60 and 90 MPa confining pressure at respectively 30, 65 and 100 degrees C. At 30 and 65 degrees C, only slow rupture was observed and the experimental fault exhibits frictional behaviour, i.e. a dependence of normal stress on peak shear stress. At 65 degrees C, a strengthening behaviour is observed after the main rupture, leading to a succession of slow rupture. At 100 degrees C, the macroscopic behaviour of the fault becomes ductile, and no dependence of pressure on the peak shear stress is observed. In addition, the increase of the confining pressure up to 60 and 90 MPa allow the transition from slow to fast rupture, highlighted by the records of acoustic activity and by dynamic stress drop occurring in a few tens of microseconds. Using strain gages located along the fault surface and acoustic transducers, we were able to measure the rupture velocities during slow and fast rupture. Slow ruptures propagated around 0.1 m/s, in agreement with natural observations. Fast ruptures propagated up the supershear velocities, i.e. faster than the shear wave speed (>3500 m/s). A complete study of the microstructures was realized before and after ruptures. Slow ruptures lead to the production of mirror-like surface driven by the production of nanograins due to dislocation processes. Fast ruptures induce the production of amorphous material along the fault surface, which may come from melting processes. We demonstrate that the transition from slow to dynamic instabilities is observed when the entire fault exhibits plastic processes, which increase the stiffness of the fault.

UTILIZING RESULTS FROM INSAR TO DEVELOP SEISMIC LOCATION BENCHMARKS AND IMPLICATIONS FOR SEISMIC SOURCE STUDIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. BEGNAUD; ET AL

2000-09-01

Obtaining accurate seismic event locations is one of the most important goals for monitoring detonations of underground nuclear teats. This is a particular challenge at small magnitudes where the number of recording stations may be less than 20. Although many different procedures are being developed to improve seismic location, most procedures suffer from inadequate testing against accurate information about a seismic event. Events with well-defined attributes, such as latitude, longitude, depth and origin time, are commonly referred to as ground truth (GT). Ground truth comes in many forms and with many different levels of accuracy. Interferometric Synthetic Aperture Radar (InSAR)more » can provide independent and accurate information (ground truth) regarding ground surface deformation and/or rupture. Relating surface deformation to seismic events is trivial when events are large and create a significant surface rupture, such as for the M{sub w} = 7.5 event that occurred in the remote northern region of the Tibetan plateau in 1997. The event, which was a vertical strike slip even appeared anomalous in nature due to the lack of large aftershocks and had an associated surface rupture of over 180 km that was identified and modeled using InSAR. The east-west orientation of the fault rupture provides excellent ground truth for latitude, but is of limited use for longitude. However, a secondary rupture occurred 50 km south of the main shock rupture trace that can provide ground truth with accuracy within 5 km. The smaller, 5-km-long secondary rupture presents a challenge for relating the deformation to a seismic event. The rupture is believed to have a thrust mechanism; the dip of the fimdt allows for some separation between the secondary rupture trace and its associated event epicenter, although not as much as is currently observed from catalog locations. Few events within the time period of the InSAR analysis are candidates for the secondary rupture. Of these, we have identified six possible secondary rupture events (mb range = 3.7-4.8, with two magnitudes not reported), based on synthetic tests and residual analysis. All of the candidate events are scattered about the main and secondary rupture. A Joint Hypocenter Determination (JHD) approach applied to the aftershocks using global picks was not able to identify the secondary event. We added regional data and used propagation path corrections to reduce scatter and remove the 20-km bias seen in the main shock location. A&r preliminary analysis using several different velocity models, none of the candidate events proved to relocate on the surface trace of the secondary rupture. However, one event (mb = not reported) moved from a starting distance of {approximately}106 km to a relocated distance of {approximately}28 km from the secondary rupture, the only candidate event to relocate in relative proximity to the secondary rupture.« less

Numerical simulation of the 1976 Ms7.8 Tangshan Earthquake

NASA Astrophysics Data System (ADS)

Li, Zhengbo; Chen, Xiaofei

2017-04-01

An Ms 7.8 earthquake happened in Tangshan in 1976, causing more than 240000 people death and almost destroying the whole city. Numerous studies indicated that the surface rupture zone extends 8 to 11 km in the south of Tangshan City. The fault system is composed with more than ten NE-trending right-lateral strike-slip left-stepping echelon faults, with a general strike direction of N30°E. However, recent scholars proposed that the surface ruptures appeared in a larger area. To simulate the rupture process closer to the real situation, the curvilinear grid finite difference method presented by Zhang et al. (2006, 2014) which can handle the free surface and the complex geometry were implemented to investigate the dynamic rupture and ground motion of Tangshan earthquake. With the data from field survey, seismic section, borehole and trenching results given by different studies, several fault geometry models were established. The intensity, the seismic waveform and the displacement resulted from the simulation of different models were compared with the observed data. The comparison of these models shows details of the rupture process of the Tangshan earthquake and implies super-shear may occur during the rupture, which is important for better understanding of this complicated rupture process and seismic hazard distributions of this earthquake.

Broadband ground-motion simulation using a hybrid approach

USGS Publications Warehouse

Graves, R.W.; Pitarka, A.

2010-01-01

This paper describes refinements to the hybrid broadband ground-motion simulation methodology of Graves and Pitarka (2004), which combines a deterministic approach at low frequencies (f 1 Hz). In our approach, fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time. The prescribed slip distribution is constrained to follow an inverse wavenumber-squared fall-off and the average rupture speed is set at 80% of the local shear-wave velocity, which is then adjusted such that the rupture propagates faster in regions of high slip and slower in regions of low slip. We use a Kostrov-like slip-rate function having a rise time proportional to the square root of slip, with the average rise time across the entire fault constrained empirically. Recent observations from large surface rupturing earthquakes indicate a reduction of rupture propagation speed and lengthening of rise time in the near surface, which we model by applying a 70% reduction of the rupture speed and increasing the rise time by a factor of 2 in a zone extending from the surface to a depth of 5 km. We demonstrate the fidelity of the technique by modeling the strong-motion recordings from the Imperial Valley, Loma Prieta, Landers, and Northridge earthquakes.

Self-Rupturing Hermetic Valve

NASA Technical Reports Server (NTRS)

Tucker, Curtis E., Jr.; Sherrit, Stewart

2011-01-01

For commercial, military, and aerospace applications, low-cost, small, reliable, and lightweight gas and liquid hermetically sealed valves with post initiation on/off capability are highly desirable for pressurized systems. Applications include remote fire suppression, single-use system-pressurization systems, spacecraft propellant systems, and in situ instruments. Current pyrotechnic- activated rupture disk hermetic valves were designed for physically larger systems and are heavy and integrate poorly with portable equipment, aircraft, and small spacecraft and instrument systems. Additionally, current pyrotechnically activated systems impart high g-force shock loads to surrounding components and structures, which increase the risk of damage and can require additional mitigation. The disclosed mechanism addresses the need for producing a hermetically sealed micro-isolation valve for low and high pressure for commercial, aerospace, and spacecraft applications. High-precision electrical discharge machining (EDM) parts allow for the machining of mated parts with gaps less than a thousandth of an inch. These high-precision parts are used to support against pressure and extrusion, a thin hermetically welded diaphragm. This diaphragm ruptures from a pressure differential when the support is removed and/or when the plunger is forced against the diaphragm. With the addition of conventional seals to the plunger and a two-way actuator, a derivative of this design would allow nonhermetic use as an on/off or metering valve after the initial rupturing of the hermetic sealing disk. In addition, in a single-use hermetically sealed isolation valve, the valve can be activated without the use of potential leak-inducing valve body penetrations. One implementation of this technology is a high-pressure, high-flow-rate rupture valve that is self-rupturing, which is advantageous for high-pressure applications such as gas isolation valves. Once initiated, this technology is self-energizing and requires low force compared to current pyrotechnic-based burst disk hermetic valves. This is a novel design for producing a single-use, self-rupturing, hermetically sealed valve for isolation of pressurized gas and/or liquids. This design can also be applied for single-use disposable valves for chemical instruments. A welded foil diaphragm is fully supported by two mated surfaces that are machined to micron accuracies using EDM. To open the valve, one of the surfaces is moved relative to the other to (a) remove the support creating an unsupported diaphragm that ruptures due to over pressure, and/or (b) produce tension in the diaphragm and rupture it.

Structure of the San Andreas Fault Zone in the Salton Trough Region of Southern California: A Comparison with San Andreas Fault Structure in the Loma Prieta Area of Central California

NASA Astrophysics Data System (ADS)

Fuis, G. S.; Catchings, R.; Scheirer, D. S.; Goldman, M.; Zhang, E.; Bauer, K.

2016-12-01

The San Andreas fault (SAF) in the northern Salton Trough, or Coachella Valley, in southern California, appears non-vertical and non-planar. In cross section, it consists of a steeply dipping segment (75 deg dip NE) from the surface to 6- to 9-km depth, and a moderately dipping segment below 6- to 9-km depth (50-55 deg dip NE). It also appears to branch upward into a flower-like structure beginning below about 10-km depth. Images of the SAF zone in the Coachella Valley have been obtained from analysis of steep reflections, earthquakes, modeling of potential-field data, and P-wave tomography. Review of seismological and geodetic research on the 1989 M 6.9 Loma Prieta earthquake, in central California (e.g., U.S. Geological Survey Professional Paper 1550), shows several features of SAF zone structure similar to those seen in the northern Salton Trough. Aftershocks in the Loma Prieta epicentral area form two chief clusters, a tabular zone extending from 18- to 9-km depth and a complex cluster above 5-km depth. The deeper cluster has been interpreted to surround the chief rupture plane, which dips 65-70 deg SW. When double-difference earthquake locations are plotted, the shallower cluster contains tabular subclusters that appear to connect the main rupture with the surface traces of the Sargent and Berrocal faults. In addition, a diffuse cluster may surround a steep to vertical fault connecting the main rupture to the surface trace of the SAF. These interpreted fault connections from the main rupture to surface fault traces appear to define a flower-like structure, not unlike that seen above the moderately dipping segment of the SAF in the Coachella Valley. But importantly, the SAF, interpreted here to include the main rupture plane, appears segmented, as in the Coachella Valley, with a moderately dipping segment below 9-km depth and a steep to vertical segment above that depth. We hope to clarify fault-zone structure in the Loma Prieta area by reanalyzing active-source data collected after the earthquake for steep reflections.

Insights into the relationship between surface and subsurface activity from mechanical modeling of the 1992 Landers M7.3 earthquake

NASA Astrophysics Data System (ADS)

Madden, E. H.; Pollard, D. D.

2009-12-01

Multi-fault, strike-slip earthquakes have proved difficult to incorporate into seismic hazard analyses due to the difficulty of determining the probability of these ruptures, despite collection of extensive data associated with such events. Modeling the mechanical behavior of these complex ruptures contributes to a better understanding of their occurrence by elucidating the relationship between surface and subsurface earthquake activity along transform faults. This insight is especially important for hazard mitigation, as multi-fault systems can produce earthquakes larger than those associated with any one fault involved. We present a linear elastic, quasi-static model of the southern portion of the 28 June 1992 Landers earthquake built in the boundary element software program Poly3D. This event did not rupture the extent of any one previously mapped fault, but trended 80km N and NW across segments of five sub-parallel, N-S and NW-SE striking faults. At M7.3, the earthquake was larger than the potential earthquakes associated with the individual faults that ruptured. The model extends from the Johnson Valley Fault, across the Landers-Kickapoo Fault, to the Homestead Valley Fault, using data associated with a six-week time period following the mainshock. It honors the complex surface deformation associated with this earthquake, which was well exposed in the desert environment and mapped extensively in the field and from aerial photos in the days immediately following the earthquake. Thus, the model incorporates the non-linearity and segmentation of the main rupture traces, the irregularity of fault slip distributions, and the associated secondary structures such as strike-slip splays and thrust faults. Interferometric Synthetic Aperture Radar (InSAR) images of the Landers event provided the first satellite images of ground deformation caused by a single seismic event and provide constraints on off-fault surface displacement in this six-week period. Insight is gained by comparing the density, magnitudes and focal plane orientations of relocated aftershocks for this time frame with the magnitude and orientation of planes of maximum Coulomb shear stress around the fault planes at depth.

Low footwall accelerations and variable surface rupture behavior on the Fort Sage Mountains fault, northeast California

USGS Publications Warehouse

Briggs, Richard W.; Wesnousky, Steven G.; Brune, James N.; Purvance, Matthew D.; Mahan, Shannon

2013-01-01

The Fort Sage Mountains fault zone is a normal fault in the Walker Lane of the western Basin and Range that produced a small surface rupture (L 5.6 earthquake in 1950. We investigate the paleoseismic history of the Fort Sage fault and find evidence for two paleoearthquakes with surface displacements much larger than those observed in 1950. Rupture of the Fort Sage fault ∼5.6  ka resulted in surface displacements of at least 0.8–1.5 m, implying earthquake moment magnitudes (Mw) of 6.7–7.1. An older rupture at ∼20.5  ka displaced the ground at least 1.5 m, implying an earthquake of Mw 6.8–7.1. A field of precariously balanced rocks (PBRs) is located less than 1 km from the surface‐rupture trace of this Holocene‐active normal fault. Ground‐motion prediction equations (GMPEs) predict peak ground accelerations (PGAs) of 0.2–0.3g for the 1950 rupture and 0.3–0.5g for the ∼5.6  ka paleoearthquake one kilometer from the fault‐surface trace, yet field tests indicate that the Fort Sage PBRs will be toppled by PGAs between 0.1–0.3g. We discuss the paleoseismic history of the Fort Sage fault in the context of the nearby PBRs, GMPEs, and probabilistic seismic hazard maps for extensional regimes. If the Fort Sage PBRs are older than the mid‐Holocene rupture on the Fort Sage fault zone, this implies that current GMPEs may overestimate near‐fault footwall ground motions at this site.

Inelastic off-fault response and three-dimensional dynamics of earthquake rupture on a strike-slip fault

USGS Publications Warehouse

Andrews, D.J.; Ma, Shuo

2010-01-01

Large dynamic stress off the fault incurs an inelastic response and energy loss, which contributes to the fracture energy, limiting the rupture and slip velocity. Using an explicit finite element method, we model three-dimensional dynamic ruptures on a vertical strike-slip fault in a homogeneous half-space. The material is subjected to a pressure-dependent Drucker-Prager yield criterion. Initial stresses in the medium increase linearly with depth. Our simulations show that the inelastic response is confined narrowly to the fault at depth. There the inelastic strain is induced by large dynamic stresses associated with the rupture front that overcome the effect of the high confining pressure. The inelastic zone increases in size as it nears the surface. For material with low cohesion (~5 MPa) the inelastic zone broadens dramatically near the surface, forming a "flowerlike" structure. The near-surface inelastic strain occurs in both the extensional and the compressional regimes of the fault, induced by seismic waves ahead of the rupture front under a low confining pressure. When cohesion is large (~10 MPa), the inelastic strain is significantly reduced near the surface and confined mostly to depth. Cohesion, however, affects the inelastic zone at depth less significantly. The induced shear microcracks show diverse orientations near the surface, owing to the low confining pressure, but exhibit mostly horizontal slip at depth. The inferred rupture-induced anisotropy at depth has the fast wave direction along the direction of the maximum compressive stress.

Comparison of coseismic near-field and off-fault surface deformation patterns of the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine earthquakes: Implications for controls on the distribution of surface strain

NASA Astrophysics Data System (ADS)

Milliner, C. W. D.; Dolan, J. F.; Hollingsworth, J.; Leprince, S.; Ayoub, F.

2016-10-01

Subpixel correlation of preevent and postevent air photos reveal the complete near-field, horizontal surface deformation patterns of the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine ruptures. Total surface displacement values for both earthquakes are systematically larger than "on-fault" displacements from geologic field surveys, indicating significant distributed, inelastic deformation occurred along these ruptures. Comparison of these two data sets shows that 46 ± 10% and 39 ± 22% of the total surface deformation were distributed over fault zones averaging 154 m and 121 m in width for the Landers and Hector Mine events, respectively. Spatial variations of distributed deformation along both ruptures show correlations with the type of near-surface lithology and degree of fault complexity; larger amounts of distributed shear occur where the rupture propagated through loose unconsolidated sediments and areas of more complex fault structure. These results have basic implications for geologic-geodetic rate comparisons and probabilistic seismic hazard analysis.

Rupture and Spreading Dynamics of Lipid Membranes on a Solid Surface

NASA Astrophysics Data System (ADS)

Perazzo, Antonio; Shin, Sangwoo; Colosqui, Carlos; Young, Yuan-Nan; Stone, Howard A.

2017-11-01

The spreading of lipid membranes on solid surfaces is a dynamic phenomenon relevant to drug delivery, endocytosis, biofouling, and the synthesis of supported lipid bilayers. Current technological developments are limited by an incomplete understanding of the spreading and adhesion dynamics of a lipid bilayer under different physicochemical conditions. Here, we present recent experimental and theoretical results for the spreading of giant unilamellar vesicles (GUVs), where the vesicle shell consists of a lipid bilayer. In particular, we study the effect of different background ion concentrations, osmolarity mismatches between the interior and the exterior of the vesicles, and different surface chemistries of the glass substrate. In all of the studied cases, we observe a delay time before a GUV in contact with the solid surface eventually ruptures. The rupture kinetics and subsequent spreading dynamics is controlled by the ionic screening within the thin film of liquid between the vesicle and the surface. Different rupture mechanisms, mobilities of the spreading vesicle, and degrees of substrate coverage are observed by varying the electrolyte concentration, solid surface charge, and osmolarity mismatch.

Evidence for surface rupture in 1868 on the Hayward Fault in North Oakland and major rupturing in prehistoric earthquakes

NASA Astrophysics Data System (ADS)

Lienkaemper, James J.; Williams, Patrick L.

1999-07-01

WGCEP90 estimated the Hayward fault to have a high probability (0.45 in 30 yr) of producing a future M7 Bay Area earthquake. This was based on a generic recurrence time and an unverified segmentation model, because there were few direct observations for the southern fault and none for the northern Hayward fault. To better constrain recurrence and segmentation of the northern Hayward fault, we trenched in north Oakland. Unexpectedly, we observed evidence of surface rupture probably from the M7 1868 earthquake. This extends the limit of that surface rupture 13 km north of the segmentation boundary used in the WGCEP90 model and forces serious re-evaluation of the current two-segment paradigm. Although we found that major prehistoric ruptures have occurred here, we could not radiocarbon date them. However, the last major prehistoric event appears correlative with a recently recognized event 13 km to the north dated AD 1640-1776.

Evidence for surface rupture in 1868 on the Hayward fault in north Oakland and major rupturing in prehistoric earthquakes

USGS Publications Warehouse

Lienkaemper, J.J.; Williams, P.L.

1999-01-01

WGCEP90 estimated the Hayward fault to have a high probability (0.45 in 30 yr) of producing a future M7 Bay Area earthquake. This was based on a generic recurrence time and an unverified segmentation model, because there were few direct observations for the southern fault and none for the northern Hayward fault. To better constrain recurrence and segmentation of the northern Hayward fault, we trenched in north Oakland. Unexpectedly, we observed evidence of surface rupture probably from the M7 1868 earthquake. This extends the limit of that surface rupture 13 km north of the segmentation boundary used in the WGCEP90 model and forces serious re-evaluation of the current two-segment paradigm. Although we found that major prehistoric ruptures have occurred here, we could not radiocarbon date them. However, the last major prehistoric event appears correlative with a recently recognized event 13 km to the north dated AD 1640-1776. Copyright 1999 by the American Geophysical Union.

Surface Rupture Map of the 2002 M7.9 Denali Fault Earthquake, Alaska: Digital Data

USGS Publications Warehouse

Haeussler, Peter J.

2009-01-01

The November 3, 2002, Mw7.9 Denali Fault earthquake produced about 340 km of surface rupture along the Susitna Glacier Thrust Fault and the right-lateral, strike-slip Denali and Totschunda Faults. Digital photogrammetric methods were primarily used to create a 1:500-scale, three-dimensional surface rupture map, and 1:6,000-scale aerial photographs were used for three-dimensional digitization in ESRI's ArcMap GIS software, using Leica's StereoAnalyst plug in. Points were digitized 4.3 m apart, on average, for the entire surface rupture. Earthquake-induced landslides, sackungen, and unruptured Holocene fault scarps on the eastern Denali Fault were also digitized where they lay within the limits of air photo coverage. This digital three-dimensional fault-trace map is superior to traditional maps in terms of relative and absolute accuracy, completeness, and detail and is used as a basis for three-dimensional visualization. Field work complements the air photo observations in locations of dense vegetation, on bedrock, or in areas where the surface trace is weakly developed. Seventeen km of the fault trace, which broke through glacier ice, were not digitized in detail due to time constraints, and air photos missed another 10 km of fault rupture through the upper Black Rapids Glacier, so that was not mapped in detail either.

Near-field fault slip of the 2016 Vettore Mw 6.6 earthquake (Central Italy) measured using low-cost GNSS.

PubMed

Wilkinson, Maxwell W; McCaffrey, Ken J W; Jones, Richard R; Roberts, Gerald P; Holdsworth, Robert E; Gregory, Laura C; Walters, Richard J; Wedmore, Luke; Goodall, Huw; Iezzi, Francesco

2017-07-04

The temporal evolution of slip on surface ruptures during an earthquake is important for assessing fault displacement, defining seismic hazard and for predicting ground motion. However, measurements of near-field surface displacement at high temporal resolution are elusive. We present a novel record of near-field co-seismic displacement, measured with 1-second temporal resolution during the 30 th October 2016 M w 6.6 Vettore earthquake (Central Italy), using low-cost Global Navigation Satellite System (GNSS) receivers located in the footwall and hangingwall of the Mt. Vettore - Mt. Bove fault system, close to new surface ruptures. We observe a clear temporal and spatial link between our near-field record and InSAR, far-field GPS data, regional measurements from the Italian Strong Motion and National Seismic networks, and field measurements of surface ruptures. Comparison of these datasets illustrates that the observed surface ruptures are the propagation of slip from depth on a surface rupturing (i.e. capable) fault array, as a direct and immediate response to the 30 th October earthquake. Large near-field displacement ceased within 6-8 seconds of the origin time, implying that shaking induced gravitational processes were not the primary driving mechanism. We demonstrate that low-cost GNSS is an accurate monitoring tool when installed as custom-made, short-baseline networks.

Geologic Inheritance and Earthquake Rupture Processes: The 1905 M ≥ 8 Tsetserleg-Bulnay Strike-Slip Earthquake Sequence, Mongolia

NASA Astrophysics Data System (ADS)

Choi, Jin-Hyuck; Klinger, Yann; Ferry, Matthieu; Ritz, Jean-François; Kurtz, Robin; Rizza, Magali; Bollinger, Laurent; Davaasambuu, Battogtokh; Tsend-Ayush, Nyambayar; Demberel, Sodnomsambuu

2018-02-01

In 1905, 14 days apart, two M 8 continental strike-slip earthquakes, the Tsetserleg and Bulnay earthquakes, occurred on the Bulnay fault system, in Mongolia. Together, they ruptured four individual faults, with a total length of 676 km. Using submetric optical satellite images "Pleiades" with ground resolution of 0.5 m, complemented by field observation, we mapped in detail the entire surface rupture associated with this earthquake sequence. Surface rupture along the main Bulnay fault is 388 km in length, striking nearly E-W. The rupture is formed by a series of fault segments that are 29 km long on average, separated by geometric discontinuities. Although there is a difference of about 2 m in the average slip between the western and eastern parts of the Bulnay rupture, along-fault slip variations are overall limited, resulting in a smooth slip distribution, except for local slip deficit at segment boundaries. We show that damage, including short branches and secondary faulting, associated with the rupture propagation, occurred significantly more often along the western part of the Bulnay rupture, while the eastern part of the rupture appears more localized and thus possibly structurally simpler. Eventually, the difference of slip between the western and eastern parts of the rupture is attributed to this difference of rupture localization, associated at first order with a lateral change in the local geology. Damage associated to rupture branching appears to be located asymmetrically along the extensional side of the strike-slip rupture and shows a strong dependence on structural geologic inheritance.

Glass rupture disk

DOEpatents

Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

2002-01-01

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction.

PubMed

Webster, Kate E; Feller, Julian A; Leigh, Warren B; Richmond, Anneka K

2014-03-01

Graft rupture of the same knee or injury to the anterior cruciate ligament (ACL) in the contralateral knee is a devastating outcome after ACL reconstruction surgery. While a number of factors have been identified as potentially increasing the risk of subsequent ACL injury, the literature is far from definitive. To determine the rates of graft rupture and contralateral ACL injury in a large cohort and to investigate patient characteristics that may be associated with these. Case-control study; Level of evidence, 3. A consecutive cohort of 750 patients who had undergone primary ACL reconstruction surgery with a minimum 3-year follow-up were questioned about the incidence of ACL graft rupture, contralateral ACL injury, family history of ACL injury, and current activity level. Patient databases provided details for age, sex, original injury mechanism, meniscus or articular surface injury, and graft diameter. Responses were received from 561 patients (75%) at a mean ± SD follow-up time of 4.8 ± 1.1 years. Anterior cruciate ligament graft ruptures occurred in 25 patients (4.5%), and contralateral ACL injuries occurred in 42 patients (7.5%). The highest incidence of further ACL injury occurred in patients younger than 20 years at the time of surgery. In this group, 29% sustained a subsequent ACL injury to either knee. The odds for sustaining an ACL graft rupture or contralateral injury increased 6- and 3-fold, respectively, for patients younger than 20 years. Returning to cutting/pivoting sports increased the odds of graft rupture by a factor of 3.9 and contralateral rupture by a factor of 5. A positive family history doubled the odds for both graft rupture and contralateral ACL injury. Patients younger than 20 years who undergo ACL reconstruction are at significantly increased risk for both graft rupture and contralateral ACL injury. Whether age per se is a risk factor or age represents a proxy for other factors remains to be determined.

How does damage affect rupture propagation across a fault stepover?

NASA Astrophysics Data System (ADS)

Cooke, M. L.; Savage, H. M.

2011-12-01

We investigate the potential for fault damage to influence earthquake rupture at fault step-overs using a mechanical numerical model that explicitly includes the generation of cracks around faults. We compare the off-fault fracture patterns and slip profiles generated along faults with a variety of frictional slip-weakening distances and step-over geometry. Models with greater damage facilitate the transfer of slip to the second fault. Increasing separation and decreasing the overlap distance reduces the transfer of slip across the step over. This is consistent with observations of rupture stopping at step-over separation greater than 4 km (Wesnousky, 2006). In cases of slip transfer, rupture is often passed to the second fault before the damage zone cracks of the first fault reach the second fault. This implies that stresses from the damage fracture tips are transmitted elastically to the second fault to trigger the onset of slip along the second fault. Consequently, the growth of damage facilitates transfer of rupture from one fault to another across the step-over. In addition, the rupture propagates along the damage-producing fault faster than along the rougher fault that does not produce damage. While this result seems counter to our understanding that damage slows rupture propagation, which is documented in our models with pre-existing damage, these model results are suggesting an additional process. The slip along the newly created damage may unclamp portions of the fault ahead of the rupture and promote faster rupture. We simulate the M7.1 Hector Mine Earthquake and compare the generated fracture patterns to maps of surface damage. Because along with the detailed damage pattern, we also know the stress drop during the earthquake, we may begin to constrain parameters like the slip-weakening distance along portions of the faults that ruptured in the Hector Mine earthquake.

Precursory, Nucleation and Propagation of Ruptures Along Heterogeneously Loaded, Circular Experimental Faults

NASA Astrophysics Data System (ADS)

Reches, Z.; Zu, X.; Jeffers, J.

2017-12-01

We explored the evolution of dynamic rupture along a circular experimental fault composed of clear acrylic blocks. The ring-shaped fault surface has inner and outer diameters of 7.72 and 10.16 cm, respectively. An array of ten rossette strain-gauges is attached to the outer rim of one block that provide the 2D strain tensor in a plane normal to the fault. The 30 components of the gauges are monitored at 10^6 samples/second. One 3D miniature accelerometer is attached to the fault block. The initial asperities of the fault surface generated a non-uniform strain (=stress) distribution that was recorded, and indicated local deviations of ±30% from the mean stress. The mean normal stress was up to 3.5 MPa, the remotely applied velocity was up to .002 m/s, and the slip velocities during rupture were not measured. The rupture characteristics, namely propagation velocity and rupture front strain-field, were determined from strain-gauge outputs. The analysis of tens of stick-slip events revealed the following preliminary results: (1) The ruptures consistently nucleated at sites of high local strains (=stresses) that were formed by the pre-shear, normal stress loading. (2) The pre-rupture nucleation process was recognized a by temporal (< 0.1 s), local (<20 mm) reduction of the shear strain. (3) Commonly, the initiation of nucleation was associated with micro acoustic emissions, whereas the initiation of rupture was associated with intense acoustic activity. (4) Nucleation could occur quasi-simultaneously at two, highly stressed sites. (5) From the nucleation site, the ruptures propagated in two directions along the ring-shaped fault, and the collision between the two fronts led to rupture `shut-off'. (5) The strain-field of rupture fronts was well-recognized for ruptures propagating faster than 50 m/s, and the fastest fronts propagated at 1000 m/s. (7) It appears that the rupture front strain-field close to the nucleation site differs from the front strain-field far from nucleation site. (8) Post-shear examination of the fault surfaces revealed evidence of brittle wear of the acrylic including gouge formation, ploughing, and powder smearing. (9) Work in progress includes attempts to achieve faster dynamic ruptures, and the utilization of the existing monitoring system to rupture granite faults.

Effects of the 2016 Kumamoto earthquakes on the Aso volcanic edifice

NASA Astrophysics Data System (ADS)

Tajima, Yasuhisa; Hasenaka, Toshiaki; Torii, Masayuki

2017-05-01

Large earthquakes occurred in the central part of Kumamoto Prefecture on April 14-16, 2016, causing severe damage to the northern segment of the Hinagu faults and the eastern segment of the Futagawa faults. Earthquake surface ruptures appeared along these faults and on the Aso volcanic edifice, which in turn generated landslides. We conducted landform change analysis of the central cones of Aso volcano by using satellite and aerial photographs. First, we categorized the topographical changes as surface scarps, arc-shaped cracks, and linear cracks. Field survey indicated that landslides caused the scarps and arc-shaped cracks, whereas faulting caused the linear cracks. We discovered a surface rupture concentration zone (RCZ) formed three ruptures bands with many surface ruptures and landslides extending from the west foot to the center of the Aso volcanic edifice. The magmatic volcanic vents that formed during the past 10,000 years are located along the north margin of the RCZ. Moreover, the distribution and dip of the core of rupture concentration zone correspond with the Nakadake craters. We conclude that a strong relationship exists between the volcanic vents and fault structures in the central cones of Aso volcano.[Figure not available: see fulltext.

Estimation of source processes of the 2016 Kumamoto earthquakes from strong motion waveforms

NASA Astrophysics Data System (ADS)

Kubo, H.; Suzuki, W.; Aoi, S.; Sekiguchi, H.

2016-12-01

In this study, we estimated the source processes for two large events of the 2016 Kumamoto earthquakes (the M7.3 event at 1:25 JST on April 16, 2016 and the M6.5 event at 21:26 JST on April 14, 2016) from strong motion waveforms using multiple-time-window linear waveform inversion (Hartzell and Heaton 1983; Sekiguchi et al. 2000). Based on the observations of surface ruptures, the spatial distribution of aftershocks, and the geodetic data, a realistic curved fault model was developed for the source-process analysis of the M7.3 event. The source model obtained for the M7.3 event with a seismic moment of 5.5 × 1019 Nm (Mw 7.1) had two significant ruptures. One rupture propagated toward the northeastern shallow region at 4 s after rupture initiation, and continued with large slips to approximately 16 s. This rupture caused a large slip region with a peak slip of 3.8 m that was located 10-30 km northeast of the hypocenter and reached the caldera of Mt. Aso. The contribution of the large slip region to the seismic waveforms was large at many stations. Another rupture propagated toward the surface from the hypocenter at 2-6 s, and then propagated toward the northeast along the near surface at 6-10 s. This rupture largely contributed to the seismic waveforms at the stations south of the fault and close to the hypocenter. A comparison with the results obtained using a single fault plane model demonstrate that the use of the curved fault model led to improved waveform fit at the stations south of the fault. The extent of the large near-surface slips in this source model for the M7.3 event is roughly consistent with the extent of the observed large surface ruptures. The source model obtained for the M6.5 event with a seismic moment of 1.7 × 1018 Nm (Mw 6.1) had large slips in the region around the hypocenter and in the shallow region north-northeast of the hypocenter, both of which had a maximum slip of 0.7 m. The rupture of the M6.5 event propagated from the former region to the latter region at 1-6 s after rupture initiation, which is expected to have caused the strong ground motions due to the forward directivity effect at KMMH16 and surroundings. The occurrence of the near-surface large slips in this source model for the M6.5 event is consistent with the appearance of small surface cracks, which were observed by some residents.

The 2016 Kaikōura earthquake: Simultaneous rupture of the subduction interface and overlying faults

NASA Astrophysics Data System (ADS)

Wang, Teng; Wei, Shengji; Shi, Xuhua; Qiu, Qiang; Li, Linlin; Peng, Dongju; Weldon, Ray J.; Barbot, Sylvain

2018-01-01

The distribution of slip during an earthquake and how it propagates among faults in the subduction system play a major role in seismic and tsunami hazards, yet they are poorly understood because offshore observations are often lacking. Here we derive the slip distribution and rupture evolution during the 2016 Mw 7.9 Kaikōura (New Zealand) earthquake that reconcile the surface rupture, space geodetic measurements, seismological and tsunami waveform records. We use twelve fault segments, with eleven in the crust and one on the megathrust interface, to model the geodetic data and match the major features of the complex surface ruptures. Our modeling result indicates that a large portion of the moment is distributed on the subduction interface, making a significant contribution to the far field surface deformation and teleseismic body waves. The inclusion of local strong motion and teleseismic waveform data in the joint inversion reveals a unilateral rupture towards northeast with a relatively low averaged rupture speed of ∼1.5 km/s. The first 30 s of the rupture took place on the crustal faults with oblique slip motion and jumped between fault segments that have large differences in strike and dip. The peak moment release occurred at ∼65 s, corresponding to simultaneous rupture of both plate interface and the overlying splay faults with rake angle changes progressively from thrust to strike-slip. The slip on the Papatea fault produced more than 2 m of offshore uplift, making a major contribution to the tsunami at the Kaikōura station, while the northeastern end of the rupture can explain the main features at the Wellington station. Our inversions and simulations illuminate complex up-dip rupture behavior that should be taken into consideration in both seismic and tsunami hazard assessment. The extreme complex rupture behavior also brings new challenges to the earthquake dynamic simulations and understanding the physics of earthquakes.

Investigating microearthquake finite source attributes with IRIS Community Wavefield Demonstration Experiment in Oklahoma

NASA Astrophysics Data System (ADS)

Fan, Wenyuan; McGuire, Jeffrey J.

2018-05-01

An earthquake rupture process can be kinematically described by rupture velocity, duration and spatial extent. These key kinematic source parameters provide important constraints on earthquake physics and rupture dynamics. In particular, core questions in earthquake science can be addressed once these properties of small earthquakes are well resolved. However, these parameters of small earthquakes are poorly understood, often limited by available datasets and methodologies. The IRIS Community Wavefield Experiment in Oklahoma deployed ˜350 three component nodal stations within 40 km2 for a month, offering an unprecedented opportunity to test new methodologies for resolving small earthquake finite source properties in high resolution. In this study, we demonstrate the power of the nodal dataset to resolve the variations in the seismic wavefield over the focal sphere due to the finite source attributes of a M2 earthquake within the array. The dense coverage allows us to tightly constrain rupture area using the second moment method even for such a small earthquake. The M2 earthquake was a strike-slip event and unilaterally propagated towards the surface at 90 per cent local S- wave speed (2.93 km s-1). The earthquake lasted ˜0.019 s and ruptured Lc ˜70 m by Wc ˜45 m. With the resolved rupture area, the stress-drop of the earthquake is estimated as 7.3 MPa for Mw 2.3. We demonstrate that the maximum and minimum bounds on rupture area are within a factor of two, much lower than typical stress drop uncertainty, despite a suboptimal station distribution. The rupture properties suggest that there is little difference between the M2 Oklahoma earthquake and typical large earthquakes. The new three component nodal systems have great potential for improving the resolution of studies of earthquake source properties.

Geomorphic features of surface ruptures associated with the 2016 Kumamoto earthquake in and around the downtown of Kumamoto City, and implications on triggered slip along active faults

NASA Astrophysics Data System (ADS)

Goto, Hideaki; Tsutsumi, Hiroyuki; Toda, Shinji; Kumahara, Yasuhiro

2017-02-01

The 30-km-long surface ruptures associated with the M w 7.0 ( M j 7.3) earthquake at 01:25 JST on April 16 in Kumamoto Prefecture appeared along the previously mapped 100-km-long active fault called the Futagawa-Hinagu fault zone (FHFZ). The surface ruptures appeared to have extended further west out of the main FHFZ into the Kumamoto Plain. Although InSAR analysis by Geospatial Information Authority of Japan (GSI) indicated coseismic surface deformation in and around the downtown of Kumamoto City, the surface ruptures have not been clearly mapped in the central part of the Kumamoto Plain, and whether there are other active faults other than the Futagawa fault in the Kumamoto Plain remained unclear. We produced topographical stereo images (anaglyph) from 5-m-mesh digital elevation model of GSI, which was generated from light detection and ranging data. We interpreted them and identified that several SW-sloping river terraces formed after the deposition of the pyroclastic flow deposits related to the latest large eruption of the Aso caldera (86.8-87.3 ka) are cut and deformed by several NW-trending flexure scarps down to the southwest. These 5.4-km-long scarps that cut across downtown Kumamoto were identified for the first time, and we name them as the Suizenji fault zone. Surface deformation such as continuous cracks, tilts, and monoclinal folding associated with the main shock of the 2016 Kumamoto earthquake was observed in the field along the fault zone. The amount of vertical deformation ( 0.1 m) along this fault associated with the 2016 Kumamoto earthquake was quite small compared to the empirically calculated coseismic slip (0.5 m) based on the fault length. We thus suggest that the slip on this fault zone was triggered by the Kumamoto earthquake, but the fault zone has potential to generate an earthquake with larger slip that poses a high seismic risk in downtown Kumamoto area.[Figure not available: see fulltext.

Ground Motion Synthetics For Spontaneous Versus Prescribed Rupture On A 45(o) Thrust Fault

NASA Astrophysics Data System (ADS)

Gottschämmer, E.; Olsen, K. B.

We have compared prescribed (kinematic) and spontaneous dynamic rupture propaga- tion on a 45(o) dipping thrust fault buried up to 5 km in a half-space model, as well as ground motions on the free surface for frequencies less than 1 Hz. The computa- tions are carried out using a 3D finite-difference method with rate-and-state friction on a planar, 20 km by 20 km fault. We use a slip-weakening distance of 15 cm and a slip- velocity weakening distance of 9.2 cm/s, similar to those for the dynamic study for the 1994 M6.7 Northridge earthquake by Nielsen and Olsen (2000) which generated satis- factory fits to selected strong motion data in the San Fernando Valley. The prescribed rupture propagation was designed to mimic that of the dynamic simulation at depth in order to isolate the dynamic free-surface effects. In this way, the results reflect the dy- namic (normal-stress) interaction with the free surface for various depths of burial of the fault. We find that the moment, peak slip and peak sliprate for the rupture breaking the surface are increased by up to 60%, 80%, and 10%, respectively, compared to the values for the scenario buried 5 km. The inclusion of these effects increases the peak displacements and velocities above the fault by factors up 3.4 and 2.9 including the increase in moment due to normal-stress effects at the free surface, and up to 2.1 and 2.0 when scaled to a Northridge-size event with surface rupture. Similar differences were found by Aagaard et al. (2001). Significant dynamic effects on the ground mo- tions include earlier arrival times caused by super-shear rupture velocities (break-out phases), in agreement with the dynamic finite-element simulations by Oglesby et al. (1998, 2000). The presence of shallow low-velocity layers tend to increase the rup- ture time and the sliprate. In particular, they promote earlier transitions to super-shear velocities and decrease the rupture velocity within the layers. Our results suggest that dynamic interaction with the free surface can significantly affect the ground motion for faults buried less than 1-3 km. We therefore recommend that strong ground motion for these scenarios be computed including such dynamic rupture effects.

Vortex Imprints at the Wall, But Not in the Bulk, Distinguish Ruptured from Unruptured Intracranial Aneurysms

NASA Astrophysics Data System (ADS)

Varble, Nicole; Meng, Hui

2015-11-01

Intracranial aneurysms affect 3% of the population. Risk stratification of aneurysms is important, as rupture often leads to death or permanent disability. Image-based CFD analyses of patient-specific aneurysms have identified low and oscillatory wall shear stress to predict rupture. These stresses are sensed biologically at the luminal wall, but the flow dynamics related to aneurysm rupture requires further understanding. We have conducted two studies: one examines vortex dynamics, and the other, high frequency flow fluctuations in patient-specific aneurysms. In the first study, based on Q-criterion vortex identification, we developed two measures to quantify regions within the aneurysm where rotational flow is dominate: the ratio of volume or surface area where Q >0 vs. the total aneurysmal volume or surface area, respectively termed volume vortex fraction (VVF) and surface vortex fraction (SVF). Statistical analysis of 204 aneurysms shows that SVF, but not VVF, distinguishes ruptured from unruptured aneurysms, suggesting that once again, the local flow patterns on the wall is directly relevant to rupture. In the second study, high-resolution CFD (high spatial and temporal resolutions and second-order discretization schemes) on 56 middle cerebral artery aneurysms shows the presence of temporal fluctuations in 8 aneurysms, but such flow instability bears no correlation with rupture. Support for this work was partially provided by NIH grant (R01 NS091075-01) and a grant from Toshiba Medical Systems Corp.

No Great Earthquake in the Central Himalaya Since 1505: a Possible Future M>=8.2 event?

NASA Astrophysics Data System (ADS)

Bilham, R.; Ambraseys, N.

2002-12-01

The re-evaluation of the past several centuries of damaging Himalayan earthquakes has largely decreased their magnitudes and/or rupture areas, with one exception. An earthquake in 1505 that simultaneously destroyed Indian cities near Agra, and Tibetan monasteries between longitudes 78° and 84° appears to be larger than any known hitherto. It occurred exactly one month after a catastrophic earthquake in Kabul, and accounts from the two earthquakes have sometimes been confused. Although the data in Tibetan accounts are sparse the event appears to have had equal violence along the 600 km northern Himalaya and in the northern plains of India. From this we infer a rupture zone possibly twice as long as that associated with recent Himalayan earthquakes, corresponding to the segment that has hitherto been termed the Central Himalayan Gap. An enigmatic observation is that surface ruptures have been exhumed in trench investigations but have not been reported from the past two centuries of 7.8

Identification of the functional groups on the surface of nanoparticles formed in photonucleation of aldehydes generated during forest fire events

NASA Astrophysics Data System (ADS)

Dultsev, Fedor N.; Mik, Ivan A.; Dubtsov, Sergei N.; Dultseva, Galina G.

2014-11-01

We describe the new procedure developed to determine the functional groups on the surface of nanoparticles formed in photonucleation of furfural, one of the aldehydes generated during forest fire events. The procedure is based on the detection of nanoparticle rupture from chemically modified surface of the quartz crystal microbalance oscillating in the thickness shear mode under voltage sweep. The rupture force is determined from the voltage at which the rupture occurs. It depends on particle mass and on the affinity of the surface functional groups of the particle to the groups that are present on the modified QCM surface. It was demonstrated with the amine modification of the surface that the nanoparticles formed in furfural photonucleation contain carbonyl and carboxyl groups. The applicability of the method for the investigation of functional groups on the surface of the nanoparticles of atmospheric aerosol is demonstrated.

A support-operator method for 3-D rupture dynamics

NASA Astrophysics Data System (ADS)

Ely, Geoffrey P.; Day, Steven M.; Minster, Jean-Bernard

2009-06-01

We present a numerical method to simulate spontaneous shear crack propagation within a heterogeneous, 3-D, viscoelastic medium. Wave motions are computed on a logically rectangular hexahedral mesh, using the generalized finite-difference method of Support Operators (SOM). This approach enables modelling of non-planar surfaces and non-planar fault ruptures. Our implementation, the Support Operator Rupture Dynamics (SORD) code, is highly scalable, enabling large-scale, multiprocessors calculations. The fault surface is modelled by coupled double nodes, where rupture occurs as dictated by the local stress conditions and a frictional failure law. The method successfully performs test problems developed for the Southern California Earthquake Center (SCEC)/U.S. Geological Survey (USGS) dynamic earthquake rupture code validation exercise, showing good agreement with semi-analytical boundary integral method results. We undertake further dynamic rupture tests to quantify numerical errors introduced by shear deformations to the hexahedral mesh. We generate a family of meshes distorted by simple shearing, in the along-strike direction, up to a maximum of 73°. For SCEC/USGS validation problem number 3, grid-induced errors increase with mesh shear angle, with the logarithm of error approximately proportional to angle over the range tested. At 73°, rms misfits are about 10 per cent for peak slip rate, and 0.5 per cent for both rupture time and total slip, indicating that the method (which, up to now, we have applied mainly to near-vertical strike-slip faulting) is also capable of handling geometries appropriate to low-angle surface-rupturing thrust earthquakes. Additionally, we demonstrate non-planar rupture effects, by modifying the test geometry to include, respectively, cylindrical curvature and sharp kinks.

Imaging the concealed section of the Whakatane fault below Whakatane city, New Zealand, with a shear wave land streamer system

NASA Astrophysics Data System (ADS)

Polom, Ulrich; Mueller, Christof; Krawczyk, CharLotte M.

2016-04-01

The Mw 7.1 Darfield Earthquake in September 2010 ruptured the surface along the Greendale Fault that was not known prior to the earthquake. The subsequent Mw 6.3 Christchurch earthquake in February 2011 demonstrated that concealed active faults have a significant risk potential for urban infrastructure and human life in New Zealand if they are located beneath or close to such areas. Mapping exposures and analysis of active faults incorporated into the National Seismic Hazard Model (NSHM) suggests that several thousands of these active structures are yet to be identified and have the potential to generate moderate to large magnitude earthquakes (i.e. magnitudes >5). Geological mapping suggests that active faults pass beneath, or within many urban areas in New Zealand, including Auckland, Blenheim, Christchurch, Hastings/Napier, Nelson, Rotorua, Taupo, Wellington, and Whakatane. Since no established methodology for routinely locating and assessing the earthquake hazard posed by concealed active faults is available, the principal objective of the presented study was to evaluate the usefulness of high-resolution shear wave seismic reflection profiling using a land streamer to locate buried faults in urban areas of New Zealand. During the survey carried out in the city of Whakatane in February 2015, the method was first tested over a well known surface outcrop of the Edgecumbe Fault 30 km south-west of Whakatane city. This allowed further to investigate the principle shear wave propagation characteristics in the unknown sediments, consisting mainly of effusive rock material of the Taupo volcanic zone mixed with marine transgression units. Subsequently the survey was continued within Whakatane city using night operation time slots to reduce the urban noise. In total, 11 profiles of 5.7 km length in high data quality were acquired, which clearly show concealed rupture structures of obviously different age in the shallow sediments down to 100 m depth. Subject to depth verification by drillings normal fault displacements of up to 15 m are visible in depths of 20-40 m, deeper rupture structures show displacements of up to 20 m. Furthermore, indications of strike-slip fault activities are visible. The concealed rupture structures found are not aligned along former estimated fault lineaments or main surface structures like the Whakatane river bed. Correlations exist with small topographic variations detected by LIDAR imaging and surface signatures on a historic map of 1867.

Women's expectations and experiences of rupture of membranes and views of the potential use of reagent pads for detecting amniotic fluid.

PubMed

Spiby, Helen; Borrelli, Sara; Hughes, Anita J

2017-12-01

To explore first-time mothers' expectations and experiences regarding rupture of membranes at term and their views on the potential use of reagent pads that detect amniotic fluid. There is little information available on women's experiences of spontaneous rupture of membranes, or interest in using methods to confirm rupture of membranes (e.g. reagent pads). Descriptive qualitative study, using focus groups and telephone interviews with women during pregnancy and after the birth of their first baby. Thematic analysis was undertaken to analyse women's responses. Ethics committee approval was obtained. Twenty-five women participated in the study of whom 13 contributed both during pregnancy and postpartum between October 2015-March 2016. Three overarching themes were identified from the data from women's expectations and experiences: uncertainty in how, when and where membranes may rupture; information which was felt to be limited and confirmation of rupture of membranes. The potential use of reagent pads met with varied responses. Women were interested in having facts and figures regarding rupture of membranes, such as characteristics of liquor; volume and probability of membranes rupturing spontaneously at term. Use of a pad as a means of confirmation was viewed as helpful, although the potential for increasing anxiety was raised. © 2017 John Wiley & Sons Ltd.

From slow to fast rupture during laboratory earthquakes in dolostones

NASA Astrophysics Data System (ADS)

Passelegue, F. X.; Fondriest, M.; Nicolas, A.; Aubry, J.; Schubnel, A.; Di Toro, G.

2016-12-01

Dolostones are the dominant lithology of the shallow portions of many seismically active regions (e.g., Italian Apennines). Displacement in natural fault zones cutting dolostones and exhumed from < 3-4 km depth is frequently localized on highly reflective (mirror-like) slip surfaces, coated with thin films of nano-granular fault rock. Using saw-cut dolostone samples, we conducted stick-slip experiments under upper crustal stress conditions (confining pressures and temperatures of 30, 60 and 90 MPa at 30, 65 and 100 °C, respectively). Samples were equipped with 15 piezoelectric transducers allowing the record of acoustic activity. At 30 and 65 °C, only slow ruptures (Vr < 200 m/s) were observed and the experimental faults exhibited ductile behaviour. At 65 °C, a slip strengthening behaviour was observed after the main slow rupture, leading to a succession of slow ruptures. At T = 100 °C and 30 MPa confining pressure, fault strengthening increased after each rupture, allowing, while the rupture processes remained slow (no acoustic activity), a sequence of slow stick-slip events. Instead, at the same ambient temperature but under larger confining pressures (60 and 90 MPa), we observed the transition from slow to fast rupture events (up to supershear rupture velocities), associated to clusters of acoustic activity and dynamic stress drop occurring in few tens of microseconds. In all experiments, mirror-like surfaces and nanoparticles were observed under the scanning electron microscope as a result of slow and fast ruptures. Clearly, mirror-like surfaces and nano powders are not representative of seismic slip events in cohesive dolostones. Instead, the transition from slow to fast ruptures (and generation of acoustic emissions) was related to a flash weakening processes, enhanced at 100° C, which allowed the experimental fault to weaken with slip faster than the rate at which the elastic strain was released from the surrounding medium.

Late Quaternary Surface Displacement Across a Normal-Fault Structural Boundary on the Northern Lost River Fault Zone (Idaho, USA)

NASA Astrophysics Data System (ADS)

DuRoss, C. B.; Bunds, M. P.; Reitman, N. G.; Gold, R. D.; Personius, S. F.; Briggs, R. W.; Toke, N. A.; Johnson, K. L.; Lajoie, L. J.

2017-12-01

In 1983, about 36 km of the 130-km-long multisegment Lost River fault zone (LRFZ) (Idaho, USA) ruptured in the M 6.9 Borah Peak earthquake. Normal-faulting surface rupture propagated along the entire 24-km-long Thousand Springs section, then branched to the northwest along a 4-km-long fault (western section) that continues into the Willow Creek Hills, a prominent bedrock ridge that forms a structural boundary between the Thousand Springs section and Warms Springs section to the north. North of the Willow Creek Hills, the 1983 rupture continued onto the southern 8 km of the 16-km-long Warm Springs section. To improve our understanding of the Borah Peak earthquake and the role of structural boundaries in normal-fault rupture propagation, we acquired low-altitude aerial imagery of the southern 8 km of the Warm Springs section and northern 6 km of the Thousand Springs section, including the western section branch fault. Using 5-10-cm-pixel digital surface models generated from this dataset, we measured vertical surface offsets across both 1983 and prehistoric scarps. On the Warm Springs section, 1983 displacement is minor (mean of 0.3 m) compared to at least two prehistoric events having mean displacements of 1.1 m and 1.7 m inferred from displacement difference curves. Prehistoric scarps on the western section indicate rupture of this branch fault prior to 1983. Correcting for 1983 displacement, mean prehistoric displacement on the western section is 0.9 m compared to a mean of 0.7 m in 1983. Using these data and previous paleoseismic displacements, we evaluate the spatial distribution of cumulative and per-earthquake displacement. Our results suggest that at least one prehistoric rupture of the Thousand Springs section occurred with a similar length and displacement to that in 1983. Further, the 1983 spillover rupture from the Thousand Springs section to the southernmost Warm Springs section appears unique from larger displacement, prehistoric ruptures that may have spanned the majority of the Warm Springs section and possibly continued south into the Willow Creek Hills based on paleoseismic and surface-offset data. We conclude that the Willow Creek Hills structural boundary has likely moderated, but not completely impeded both prehistoric and 1983 ruptures of the northern LRFZ.

Detailed Surface Rupture Geometry from the 2016 Amatrice Earthquake

NASA Astrophysics Data System (ADS)

Mildon, Z. K.; Iezzi, F.; Wedmore, L. N. J.; Gregory, L. C.; McCaffrey, K. J. W.; Wilkinson, M. W.; Faure Walker, J.; Roberts, G.; Livio, F.; Vittori, E.; Michetti, A.; Frigerio, C.; Ferrario, F.; Blumetti, A. M.; Guerrieri, L.; Di Manna, P.; Comerci, V.

2016-12-01

The Amatrice earthquake was generated by co-rupture of the Mt. Vettore and Laga faults at depth. Surface ruptures were observed for 5km along the Mt. Vettore fault, with no clear observations on the Laga fault reported to date. The surface rupture on Mt. Vettore manifests as a 15-20cm pale stripe at the base of a 60-80o dipping bedrock fault scarp and similar magnitude vertical offsets of colluvial deposits. We have measured the strike and dip of the fault alongside the coseismic throw, heave, and slip azimuth along the length of the rupture with high spatial resolution (c.2-6m, >2000 measurements). The slip azimuth is relatively constant between 210-270° even where the rupture faces uphill at its SE termination which is consistent with the regional NW-SE extension direction, defined by focal mechanisms and borehole break-out data. The simplest coseismic throw profile that would be expected is quasi-symmetric. However we found the highest values of throw (Inter Quartile Range 15-19.5cm) are skewed towards the NW end on a 1.7 km section of the fault that is oblique relative to the overall fault strike. In the centre of the rupture, orientated close to the overall fault strike, the throw is lower (IQR 7.5-13cm) and discontinuous along strike. We suggest that the skewed throw profile occurs because the strike, dip and throw must vary systematically in order to preserve the principal strain rate across a fault, in agreement with previous publications. The density of our measurements, crucially including the slip azimuth, allows us to resolve the regional debate over whether normal fault ruptures are primary tectonic features or landslides of hangingwall sediments. If the surface offsets are due to landslides, then the slip azimuth should correlate with the downslope direction of the hangingwall. We show using an available 10m DEM that this is not the case and hence the surface offsets described herein are a primary tectonic feature. This presentation offers new insights into rupture processes because of the high resolution of the dataset collected rapidly after the earthquake, but crucially because it includes the slip vector azimuth, allowing a full description of the kinematics of the faulting relative to the regional stress field and local topographic variations.

Modeling 3D Dynamic Rupture on Arbitrarily-Shaped faults by Boundary-Conforming Finite Difference Method

NASA Astrophysics Data System (ADS)

Zhu, D.; Zhu, H.; Luo, Y.; Chen, X.

2008-12-01

We use a new finite difference method (FDM) and the slip-weakening law to model the rupture dynamics of a non-planar fault embedded in a 3-D elastic media with free surface. The new FDM, based on boundary- conforming grid, sets up the mapping equations between the curvilinear coordinate and the Cartesian coordinate and transforms irregular physical space to regular computational space; it also employs a higher- order non-staggered DRP/opt MacCormack scheme which is of low dispersion and low dissipation so that the high accuracy and stability of our rupture modeling are guaranteed. Compared with the previous methods, not only we can compute the spontaneous rupture of an arbitrarily shaped fault, but also can model the influence of the surface topography on the rupture process of earthquake. In order to verify the feasibility of this method, we compared our results and other previous results, and found out they matched perfectly. Thanks to the boundary-conforming FDM, problems such as dynamic rupture with arbitrary dip, strike and rake over an arbitrary curved plane can be handled; and supershear or subshear rupture can be simulated with different parameters such as the initial stresses and the critical slip displacement Dc. Besides, our rupture modeling is economical to be implemented owing to its high efficiency and does not suffer from displacement leakage. With the help of inversion data of rupture by field observations, this method is convenient to model rupture processes and seismograms of natural earthquakes.

Adjoint analysis of the source and path sensitivities of basin-guided waves

NASA Astrophysics Data System (ADS)

Day, Steven M.; Roten, Daniel; Olsen, Kim B.

2012-05-01

Simulations of earthquake rupture on the southern San Andreas Fault (SAF) reveal large amplifications in the San Gabriel and Los Angeles Basins (SGB and LAB) apparently associated with long-range path effects. Geometrically similar excitation patterns can be recognized repeatedly in different SAF simulations (e.g. Love wave-like energy with predominant period around 4 s, channelled southwestwardly from the SGB into LAB), yet the amplitudes with which these distinctive wavefield patterns are excited change, depending upon source details (slip distribution, direction and velocity of rupture). We describe a method for rapid calculation of the sensitivity of such predicted wavefield features to perturbations of the source kinematics, using a time-reversed (adjoint) wavefield simulation. The calculations are analogous to those done in adjoint tomography, and the same time-reversed calculation also yields path-sensitivity kernels that give further insight into the excitation mechanism. For rupture on the southernmost 300 km of SAF, LAB excitation is greatest for slip concentrated between the northern Coachella Valley and the transverse ranges, propagating to the NE and with rupture velocities between 3250 and 3500 m s-1 along that fault segment; that is, within or slightly above the velocity range (between Rayleigh and S velocities) that is energetically precluded in the limit of a sharp rupture front, highlighting the potential value of imposing physical constraints (such as from spontaneous rupture models) on source parametrizations. LAB excitation is weak for rupture to the SW and for ruptures in either direction located north of the transverse transverse ranges, whereas Ventura Basin (VTB) is preferentially excited by NE ruptures situated north of the transverse ranges. Path kernels show that LAB excitation is mediated by surface waves deflected by the velocity contrast along the southern margin of the transverse ranges, having most of their energy in basement rock until they impinge on the eastern edge of SGB, through which they are then funnelled into LAB. VTB amplification is enhanced by a similar waveguide effect.

The Greenville Fault: preliminary estimates of its long-term creep rate and seismic potential

USGS Publications Warehouse

Lienkaemper, James J.; Barry, Robert G.; Smith, Forrest E.; Mello, Joseph D.; McFarland, Forrest S.

2013-01-01

Once assumed locked, we show that the northern third of the Greenville fault (GF) creeps at 2 mm/yr, based on 47 yr of trilateration net data. This northern GF creep rate equals its 11-ka slip rate, suggesting a low strain accumulation rate. In 1980, the GF, easternmost strand of the San Andreas fault system east of San Francisco Bay, produced a Mw5.8 earthquake with a 6-km surface rupture and dextral slip growing to ≥2 cm on cracks over a few weeks. Trilateration shows a 10-cm post-1980 transient slip ending in 1984. Analysis of 2000-2012 crustal velocities on continuous global positioning system stations, allows creep rates of ~2 mm/yr on the northern GF, 0-1 mm/yr on the central GF, and ~0 mm/yr on its southern third. Modeled depth ranges of creep along the GF allow 5-25% aseismic release. Greater locking in the southern two thirds of the GF is consistent with paleoseismic evidence there for large late Holocene ruptures. Because the GF lacks large (>1 km) discontinuities likely to arrest higher (~1 m) slip ruptures, we expect full-length (54-km) ruptures to occur that include the northern creeping zone. We estimate sufficient strain accumulation on the entire GF to produce Mw6.9 earthquakes with a mean recurrence of ~575 yr. While the creeping 16-km northern part has the potential to produce a Mw6.2 event in 240 yr, it may rupture in both moderate (1980) and large events. These two-dimensional-model estimates of creep rate along the southern GF need verification with small aperture surveys.

Three-dimensional fault framework of the 2014 South Napa Earthquake, San Francisco Bay region, California

NASA Astrophysics Data System (ADS)

Graymer, R. W.

2014-12-01

Assignment of the South Napa earthquake to a mapped fault is difficult, as it occurred where three large, northwest-trending faults converge and may interact in the subsurface. The surface rupture did not fall on the main trace of any of these faults, but instead between the Carneros and West Napa faults and northwest along strike from the northern mapped end of the Franklin Fault. The 2014 rupture plane appears to be nearly vertical, based on focal mechanisms of the mainshock and connection of the surface trace/rupture to the relocated hypocenter (J. Hardebeck, USGS). 3D surfaces constructed from published data show that the Carneros Fault is a steeply west-dipping fault that runs just west of the near-vertical 2014 rupture plane. The Carneros Fault does not appear to have been involved in the earthquake, although relocated aftershocks suggest possible minor triggered slip. The main West Napa Fault is also steeply west-dipping and that its projection intersects the 2014 rupture plane at around the depth of the mainshock hypocenter. UAVSAR data (A. Donnellan, JPL) and relocated aftershocks suggest that the main West Napa Fault experienced triggered slip/afterslip along a length of roughly 20 km. It is possible that the 2014 rupture took place along a largely unrecognized westerly strand of the West Napa Fault. The Franklin Fault is a steeply east-dipping fault (with a steeply west-dipping subordinate trace east of Mare Island) that has documented late Quaternary offset. Given the generally aligned orientation of the 3D fault surfaces, an alternative interpretation is that the South Napa earthquake occurred on the northernmost reach of the Franklin Fault within it's 3D junction with the West Napa Fault. This interpretation is supported, but not proven, by a short but prominent linear feature in the UAVSAR data at Slaughterhouse Point west of Vallejo, along trend south-southeast of the observed coseismic surface rupture.

Monte Carlo simulation of liquid bridge rupture: Application to lung physiology

NASA Astrophysics Data System (ADS)

Alencar, Adriano M.; Wolfe, Elie; Buldyrev, Sergey V.

2006-08-01

In the course of certain lung diseases, the surface properties and the amount of fluids coating the airways changes and liquid bridges may form in the small airways blocking the flow of air, impairing gas exchange. During inhalation, these liquid bridges may rupture due to mechanical instability and emit a discrete sound event called pulmonary crackle, which can be heard using a simple stethoscope. We hypothesize that this sound is a result of the acoustical release of energy that had been stored in the surface of liquid bridges prior to its rupture. We develop a lattice gas model capable of describing these phenomena. As a step toward modeling this process, we address a simpler but related problem, that of a liquid bridge between two planar surfaces. This problem has been analytically solved and we use this solution as a validation of the lattice gas model of the liquid bridge rupture. Specifically, we determine the surface free energy and critical stability conditions in a system containing a liquid bridge of volume Ω formed between two parallel planes, separated by a distance 2h , with a contact angle Θ using both Monte Carlo simulation of a lattice gas model and variational calculus based on minimization of the surface area with the volume and the contact angle constraints. In order to simulate systems with different contact angles, we vary the parameters between the constitutive elements of the lattice gas. We numerically and analytically determine the phase diagram of the system as a function of the dimensionless parameters hΩ-1/3 and Θ . The regions of this phase diagram correspond to the mechanical stability and thermodynamical stability of the liquid bridge. We also determine the conditions for the symmetrical versus asymmetrical rupture of the bridge. We numerically and analytically compute the release of free energy during rupture. The simulation results are in agreement with the analytical solution. Furthermore, we discuss the results in connection to the rupture of similar bridges that exist in diseased lungs.

Interseismic Coupling-Based Earthquake and Tsunami Scenarios for the Nankai Trough

NASA Astrophysics Data System (ADS)

Baranes, H.; Woodruff, J. D.; Loveless, J. P.; Hyodo, M.

2018-04-01

Theoretical modeling and investigations of recent subduction zone earthquakes show that geodetic estimates of interseismic coupling and the spatial distribution of coseismic rupture are correlated. However, the utility of contemporary coupling in guiding construction of rupture scenarios has not been evaluated on the world's most hazardous faults. Here we demonstrate methods for scaling coupling to slip to create rupture models for southwestern Japan's Nankai Trough. Results show that coupling-based models produce distributions of ground surface deformation and tsunami inundation that are similar to historical and geologic records of the largest known Nankai earthquake in CE 1707 and to an independent, quasi-dynamic rupture model. Notably, these models and records all support focused subsidence around western Shikoku that makes the region particularly vulnerable to flooding. Results imply that contemporary coupling mirrors the slip distribution of a full-margin, 1707-type rupture, and Global Positioning System measurements of surface motion are connected with the trough's physical characteristics.

Near-Field Deformation Associated with the M6.0 South Napa Earthquake Surface Rupture

NASA Astrophysics Data System (ADS)

Brooks, B. A.; Hudnut, K. W.; Glennie, C. L.; Ericksen, T.

2014-12-01

We characterize near-field deformation associated with the surface rupture of the M6.0 South Napa earthquake from repeat mobile laser scanning (MLS) surveys. Starting the day after the main shock, we operated, sometime simultaneously, short (~75 m range) and medium (~400m range) range laser scanners on a truck or backpack. We scanned most of the length of the principal and secondary surface ruptures at speeds less than 10 km/hr. Scanning occurred primarily in either suburban subdivisions or cultivated vineyards of varying varietals with differing leaf patterns and stages of maturity. Spot-spacing is dense enough (100s of points/m^2) to permit creation of 10-25cm digital elevation models of much of the surface rupture. Scanned features of the right-lateral rupture include classic mole tracks through a variety of soil types, en echelon cracks, offset vine rows, and myriad types of pavement-related deformation. We estimate coseismic surface displacements ranging from 5 to 45 cm by examining offset cultural features and vine rows and by comparing the MLS data with preexisting airborne laser scans from 2003 using point-cloud and solid-modeling methodologies. Additionally, we conducted repeat MLS scans to measure the magnitude and spatial variation of fault afterslip, exceeding 20 cm in some places, particularly in the southern portion of the rupture zone. We anticipate these data sets, in conjunction with independently collected ground-based alinement arrays and space-based geodetic data will contribute significant insight into topics of current debate including assessing the most appropriate material models for shallow fault zones and how shallow and deeper fault slip relate to one another.

Effect of Sediments on Rupture Dynamics of Shallow Subduction Zone Earthquakes and Tsunami Generation

NASA Astrophysics Data System (ADS)

Ma, S.

2011-12-01

Low-velocity fault zones have long been recognized for crustal earthquakes by using fault-zone trapped waves and geodetic observations on land. However, the most pronounced low-velocity fault zones are probably in the subduction zones where sediments on the seafloor are being continuously subducted. In this study I focus on shallow subduction zone earthquakes; these earthquakes pose a serious threat to human society in their ability in generating large tsunamis. Numerous observations indicate that these earthquakes have unusually long rupture durations, low rupture velocities, and/or small stress drops near the trench. However, the underlying physics is unclear. I will use dynamic rupture simulations with a finite-element method to investigate the dynamic stress evolution on faults induced by both sediments and free surface, and its relations with rupture velocity and slip. I will also explore the effect of off-fault yielding of sediments on the rupture characteristics and seafloor deformation. As shown in Ma and Beroza (2008), the more compliant hanging wall combined with free surface greatly increases the strength drop and slip near the trench. Sediments in the subduction zone likely have a significant role in the rupture dynamics of shallow subduction zone earthquakes and tsunami generation.

Potentially induced earthquakes in Oklahoma, USA: links between wastewater injection and the 2011 Mw 5.7 earthquake sequence

USGS Publications Warehouse

Keranen, Katie M.; Savage, Heather M.; Abers, Geoffrey A.; Cochran, Elizabeth S.

2013-01-01

Significant earthquakes are increasingly occurring within the continental interior of the United States, including five of moment magnitude (Mw) ≥ 5.0 in 2011 alone. Concurrently, the volume of fluid injected into the subsurface related to the production of unconventional resources continues to rise. Here we identify the largest earthquake potentially related to injection, an Mw 5.7 earthquake in November 2011 in Oklahoma. The earthquake was felt in at least 17 states and caused damage in the epicentral region. It occurred in a sequence, with 2 earthquakes of Mw 5.0 and a prolific sequence of aftershocks. We use the aftershocks to illuminate the faults that ruptured in the sequence, and show that the tip of the initial rupture plane is within ~200 m of active injection wells and within ~1 km of the surface; 30% of early aftershocks occur within the sedimentary section. Subsurface data indicate that fluid was injected into effectively sealed compartments, and we interpret that a net fluid volume increase after 18 yr of injection lowered effective stress on reservoir-bounding faults. Significantly, this case indicates that decades-long lags between the commencement of fluid injection and the onset of induced earthquakes are possible, and modifies our common criteria for fluid-induced events. The progressive rupture of three fault planes in this sequence suggests that stress changes from the initial rupture triggered the successive earthquakes, including one larger than the first.

Thermodiffusion as a means to manipulate liquid film dynamics on chemically patterned surfaces

PubMed Central

Kalpathy, Sreeram K.; Shreyes, Amrita Ravi

2017-01-01

The model problem examined here is the stability of a thin liquid film consisting of two miscible components, resting on a chemically patterned solid substrate and heated from below. In addition to surface tension gradients, the temperature variations also induce gradients in the concentration of the film by virtue of thermodiffusion/Soret effects. We study the stability and dewetting behaviour due to the coupled interplay between thermal gradients, Soret effects, long-range van der Waals forces, and wettability gradient-driven flows. Linear stability analysis is first employed to predict growth rates and the critical Marangoni number for chemically homogeneous surfaces. Then, nonlinear simulations are performed to unravel the interfacial dynamics and possible locations of the film rupture on chemically patterned substrates. Results suggest that appropriate tuning of the Soret parameter and its direction, in conjunction with either heating or cooling, can help manipulate the location and time scales of the film rupture. The Soret effect can either potentially aid or oppose film instability depending on whether the thermal and solutal contributions to flow are cooperative or opposed to each other. PMID:28595391

Empirical Relationships Among Magnitude and Surface Rupture Characteristics of Strike-Slip Faults: Effect of Fault (System) Geometry and Observation Location, Dervided From Numerical Modeling

NASA Astrophysics Data System (ADS)

Zielke, O.; Arrowsmith, J.

2007-12-01

In order to determine the magnitude of pre-historic earthquakes, surface rupture length, average and maximum surface displacement are utilized, assuming that an earthquake of a specific size will cause surface features of correlated size. The well known Wells and Coppersmith (1994) paper and other studies defined empirical relationships between these and other parameters, based on historic events with independently known magnitude and rupture characteristics. However, these relationships show relatively large standard deviations and they are based only on a small number of events. To improve these first-order empirical relationships, the observation location relative to the rupture extent within the regional tectonic framework should be accounted for. This however cannot be done based on natural seismicity because of the limited size of datasets on large earthquakes. We have developed the numerical model FIMozFric, based on derivations by Okada (1992) to create synthetic seismic records for a given fault or fault system under the influence of either slip- or stress boundary conditions. Our model features A) the introduction of an upper and lower aseismic zone, B) a simple Coulomb friction law, C) bulk parameters simulating fault heterogeneity, and D) a fault interaction algorithm handling the large number of fault patches (typically 5,000-10,000). The joint implementation of these features produces well behaved synthetic seismic catalogs and realistic relationships among magnitude and surface rupture characteristics which are well within the error of the results by Wells and Coppersmith (1994). Furthermore, we use the synthetic seismic records to show that the relationships between magntiude and rupture characteristics are a function of the observation location within the regional tectonic framework. The model presented here can to provide paleoseismologists with a tool to improve magnitude estimates from surface rupture characteristics, by incorporating the regional and local structural context which can be determined in the field: Assuming a paleoseismologist measures the offset along a fault caused by an earthquake, our model can be used to determine the probability distribution of magnitudes which are capable of producing the observed offset, accounting for regional tectonic setting and observation location.

Ruptured thought: rupture as a critical attitude to nursing research.

PubMed

Beedholm, Kirsten; Lomborg, Kirsten; Frederiksen, Kirsten

2014-04-01

In this paper, we introduce the notion of ‘rupture’ from the French philosopher Michel Foucault, whose studies of discourse and governmentality have become prominent within nursing research during the last 25 years. We argue that a rupture perspective can be helpful for identifying and maintaining a critical potential within nursing research. The paper begins by introducing rupture as an inheritance from the French epistemological tradition. It then describes how rupture appears in Foucault's works, as both an overall philosophical approach and as an analytic tool in his historical studies. Two examples of analytical applications of rupture are elaborated. In the first example, rupture has inspired us to make an effort to seek alternatives to mainstream conceptions of the phenomenon under study. In the second example, inspired by Foucault's work on discontinuity, we construct a framework for historical epochs in nursing history. The paper concludes by discussing the potential of the notion of rupture as a response to the methodological concerns regarding the use of Foucault-inspired discourse analysis within nursing research. We agree with the critique of Cheek that the critical potential of discourse analysis is at risk of being undermined by research that tends to convert the approach into a fixed method.

Intermediate Temperature Stress Rupture of a Woven Hi-Nicalon, BN-Interphase, SiC Matric Composite in Air

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurst, Janet; Brewer, David

1999-01-01

Woven Hi-Nicalon (TM) reinforced melt-infiltrated SiC matrix composites were tested under tensile stress-rupture conditions in air at intermediate temperatures. A comprehensive examination of the damage state and the fiber properties at failure was performed. Modal acoustic emission analysis was used to monitor damage during the experiment. Extensive microscopy of the composite fracture surfaces and the individual fiber fracture surfaces was used to determine the mechanisms leading to ultimate failure. The rupture properties of these composites were significantly worse than expected compared to the fiber properties under similar conditions. This was due to the oxidation of the BN interphase. Oxidation occurred through the matrix cracks that intersected the surface or edge of a tensile bar. These oxidation reactions resulted in minor degradation to fiber strength and strong bonding of the fibers to one another at regions of near fiber-to-fiber contact. It was found that two regimes for rupture exist for this material: a high stress regime where rupture occurs at a fast rate and a low stress regime where rupture occurs at a slower rate. For the high stress regime, the matrix damage state consisted of through thickness cracks. The average fracture strength of fibers that were pulled-out (the final fibers to break before ultimate failure) was controlled by the slow-crack growth rupture criterion in the literature for individual Hi-Nicalon (TM) fibers. For the low stress regime, the matrix damage state consisted of microcracks which grew during the rupture test. The average fracture strength of fibers that were pulled-out in this regime was the same as the average fracture strength of individual fibers pulled out in as-produced composites tested at room temperature.

Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale-gas reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rutqvist, Jonny; Rinaldi, Antonio P.; Cappa, Frédéric

2013-07-01

We have conducted numerical simulation studies to assess the potential for injection-induced fault reactivation and notable seismic events associated with shale-gas hydraulic fracturing operations. The modeling is generally tuned towards conditions usually encountered in the Marcellus shale play in the Northeastern US at an approximate depth of 1500 m (~;;4,500 feet). Our modeling simulations indicate that when faults are present, micro-seismic events are possible, the magnitude of which is somewhat larger than the one associated with micro-seismic events originating from regular hydraulic fracturing because of the larger surface area that is available for rupture. The results of our simulations indicatedmore » fault rupture lengths of about 10 to 20 m, which, in rare cases can extend to over 100 m, depending on the fault permeability, the in situ stress field, and the fault strength properties. In addition to a single event rupture length of 10 to 20 m, repeated events and aseismic slip amounted to a total rupture length of 50 m, along with a shear offset displacement of less than 0.01 m. This indicates that the possibility of hydraulically induced fractures at great depth (thousands of meters) causing activation of faults and creation of a new flow path that can reach shallow groundwater resources (or even the surface) is remote. The expected low permeability of faults in producible shale is clearly a limiting factor for the possible rupture length and seismic magnitude. In fact, for a fault that is initially nearly-impermeable, the only possibility of larger fault slip event would be opening by hydraulic fracturing; this would allow pressure to penetrate the matrix along the fault and to reduce the frictional strength over a sufficiently large fault surface patch. However, our simulation results show that if the fault is initially impermeable, hydraulic fracturing along the fault results in numerous small micro-seismic events along with the propagation, effectively preventing larger events from occurring. Nevertheless, care should be taken with continuous monitoring of induced seismicity during the entire injection process to detect any runaway fracturing along faults.« less

Earthquake rupture process recreated from a natural fault surface

USGS Publications Warehouse

Parsons, Thomas E.; Minasian, Diane L.

2015-01-01

What exactly happens on the rupture surface as an earthquake nucleates, spreads, and stops? We cannot observe this directly, and models depend on assumptions about physical conditions and geometry at depth. We thus measure a natural fault surface and use its 3D coordinates to construct a replica at 0.1 m resolution to obviate geometry uncertainty. We can recreate stick-slip behavior on the resulting finite element model that depends solely on observed fault geometry. We clamp the fault together and apply steady state tectonic stress until seismic slip initiates and terminates. Our recreated M~1 earthquake initiates at contact points where there are steep surface gradients because infinitesimal lateral displacements reduce clamping stress most efficiently there. Unclamping enables accelerating slip to spread across the surface, but the fault soon jams up because its uneven, anisotropic shape begins to juxtapose new high-relief sticking points. These contacts would ultimately need to be sheared off or strongly deformed before another similar earthquake could occur. Our model shows that an important role is played by fault-wall geometry, though we do not include effects of varying fluid pressure or exotic rheologies on the fault surfaces. We extrapolate our results to large fault systems using observed self-similarity properties, and suggest that larger ruptures might begin and end in a similar way, though the scale of geometrical variation in fault shape that can arrest a rupture necessarily scales with magnitude. In other words, fault segmentation may be a magnitude dependent phenomenon and could vary with each subsequent rupture.

Controls on Patterns of Repeated Fault Rupture: Examples From the Denali and Bear River Faults

NASA Astrophysics Data System (ADS)

Schwartz, D. P.; Hecker, S.

2013-12-01

A requirement for estimating seismic hazards is assigning magnitudes to earthquake sources. This relies on anticipating rupture length and slip along faults. Fundamental questions include whether lengths of past surface ruptures can be reasonably determined from fault zone characteristics and whether the variability in length and slip during repeated faulting can be constrained. To address these issues, we look at rupture characteristics and their possible controls from examples in very different tectonic settings: the high slip rate (≥15 mm/yr) Denali fault system, Alaska, and the recently activated Bear River normal fault, Wyoming-Utah. The 2002 rupture of the central Denali fault (CDF) is associated with two noteworthy geometric features. First, rupture initiated where the Susitna Glacier thrust fault (SG) intersects the CDF at depth, near the apex of a structurally complex restraining bend along the Denali. Paleoseismic data show that for the past 700 years the timing of large surface ruptures on the Denali fault west of the 2002 rupture has been distinct from those along the CDF. For the past ~6ka the frequency of SG to Denali ruptures has been ~1:12, indicating that this complexity of the 2002 rupture has not been common. Second, rupture propagated off of one strike-slip fault (CDF) onto another (the Totschunda fault, TF), an occurrence that seldom has been observed. LiDAR mapping of the intersection shows direct connectivity of the two faults--the CDF simply branches into both the TF and the eastern Denali fault (EDF). Differences in the timing of earthquakes during the past 700-800 years at sites surrounding this intersection, and estimates of accumulated slip from slip rates, indicate that for the 2002 rupture sufficient strain had accumulated on the TF to favor its failure. In contrast, the penultimate CDF rupture, with the same slip distribution as in 2002, appears to have stopped at or near the branch point, implying that neither the TF nor the EDF was stressed sufficiently to fail at that time. The Bear River fault zone (BRFZ) is a young normal fault along the eastern margin of basin-range extension that appears to have reactivated a ramp in the Laramide-age Darby-Hogsback thrust. The entire Cenozoic history of the BRFZ may consist of only two surface-rupturing events in the late Holocene (one at ~5 ka and the most recent at ~2.5 ka). The 40-km-long fault comprises synthetic and antithetic scarps extending across a zone up to 5 km wide. Remote sensing, including airborne LiDAR, and field studies show that, despite the complexity, the pattern of faulting was similar (in location and amount) for each of the two events and, at the south end, was strongly influenced by the east-west-trending Uinta Arch. Pre-existing structure clearly has exerted a first-order control on moment release on this immature fault. As shown by these examples, data on timing of surface ruptures, coseismic slip, slip rate, and fault geometry can provide a basis to constrain lengths of past and future earthquake ruptures, including possible alternative rupture scenarios. The difficult question for hazard analysis is whether the available data capture the full range of behavior and with what relative frequency do the alternatives occur?

Statistical relations among earthquake magnitude, surface rupture length, and surface fault displacement

USGS Publications Warehouse

Bonilla, Manuel G.; Mark, Robert K.; Lienkaemper, James J.

1984-01-01

In order to refine correlations of surface-wave magnitude, fault rupture length at the ground surface, and fault displacement at the surface by including the uncertainties in these variables, the existing data were critically reviewed and a new data base was compiled. Earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the Gutenberg methods and results, which make up much of the data base. Measurement errors were estimated for the three variables for 58 moderate to large shallow-focus earthquakes. Regression analyses were then made utilizing the estimated measurement errors.The regression analysis demonstrates that the relations among the variables magnitude, length, and displacement are stochastic in nature. The stochastic variance, introduced in part by incomplete surface expression of seismogenic faulting, variation in shear modulus, and regional factors, dominates the estimated measurement errors. Thus, it is appropriate to use ordinary least squares for the regression models, rather than regression models based upon an underlying deterministic relation in which the variance results primarily from measurement errors.Significant differences exist in correlations of certain combinations of length, displacement, and magnitude when events are grouped by fault type or by region, including attenuation regions delineated by Evernden and others.Estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating Ms with the logarithms of rupture length, fault displacement, or the product of length and displacement.Fault rupture area could be reliably estimated for about 20 of the events in the data set. Regression of Ms on rupture area did not result in a marked improvement over regressions that did not involve rupture area. Because no subduction-zone earthquakes are included in this study, the reported results do not apply to such zones.

Statistical relations among earthquake magnitude, surface rupture length, and surface fault displacement

USGS Publications Warehouse

Bonilla, M.G.; Mark, R.K.; Lienkaemper, J.J.

1984-01-01

In order to refine correlations of surface-wave magnitude, fault rupture length at the ground surface, and fault displacement at the surface by including the uncertainties in these variables, the existing data were critically reviewed and a new data base was compiled. Earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the Gutenberg methods and results, which necessarily make up much of the data base. Measurement errors were estimated for the three variables for 58 moderate to large shallow-focus earthquakes. Regression analyses were then made utilizing the estimated measurement errors. The regression analysis demonstrates that the relations among the variables magnitude, length, and displacement are stochastic in nature. The stochastic variance, introduced in part by incomplete surface expression of seismogenic faulting, variation in shear modulus, and regional factors, dominates the estimated measurement errors. Thus, it is appropriate to use ordinary least squares for the regression models, rather than regression models based upon an underlying deterministic relation with the variance resulting from measurement errors. Significant differences exist in correlations of certain combinations of length, displacement, and magnitude when events are qrouped by fault type or by region, including attenuation regions delineated by Evernden and others. Subdivision of the data results in too few data for some fault types and regions, and for these only regressions using all of the data as a group are reported. Estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating M with the logarithms of rupture length, fault displacement, or the product of length and displacement. Fault rupture area could be reliably estimated for about 20 of the events in the data set. Regression of MS on rupture area did not result in a marked improvement over regressions that did not involve rupture area. Because no subduction-zone earthquakes are included in this study, the reported results do not apply to such zones.

Complex ruptures during hydraulic fracturing of the Marcellus Shale

NASA Astrophysics Data System (ADS)

Viegas, G. F.; Urbancic, T.; Bosman, K.; Baig, A. M.

2016-12-01

Complex rupture patterns were observed on several M0+ events recorded during a hydraulic stimulation of the Marcellus shale. Although M>0 events associated with hydraulic fracturing have now been commonly recorded and may cause concern in terms of public and infrastructure safety, the vast majority of these events are smaller than M3 and are not felt at the surface. We investigate the rupture characteristics of one such multi-rupture event with 3 sub-events, by examining the failure dynamics of the overall fracture itself and of each individual sub-event, and the growth of the overall fracture from rupture initiation to arrest. This analysis is only possible due to the wide frequency range of the seismic monitoring system put in place which spanned from 0.1 Hz to 1000 Hz. The monitoring system consists of: high-frequency sensor-arrays of geophones deployed downhole close to the reservoir and thus to the rupture initiation point; and low to intermediate frequency accelerometers and geophones deployed at intermediate and shallow depths, allowing for the investigation of overall rupture characteristics. We aim to gain an understanding of the role of asperities, fracture roughness, and fluids on the different aspects of the rupture processes and of the failure mechanisms (shearing versus tensile dominance of behavior) associated with these complex events. Our results show that the overall event is characterized by the failure of multiple asperities and the distance between the 3 sub-events is less than 20 m. We observe decreasing stress drop and increasing Mw over time for the successive sub-events which suggest decreasing frictional resistance due to the presence of fluids over an increasingly large rupture surface akin to increased slip over a larger and less resistant contact area such as an asperity. The overall failure shows a dominant shearing mode mechanism whereas the sub-events failures show strong tensile components. The ruptures of the 1st and 2nd sub-events are indicative of shear-compaction of an asperity and the one of the 3rd sub-event is suggestive of a rupture riding over several surface patches. Additional analysis of other complex events will improve the characterization of the rupture processes of these larger-magnitude events and allow for the assessment of conditions under which the failures occur.

Maximum magnitude estimations of induced earthquakes at Paradox Valley, Colorado, from cumulative injection volume and geometry of seismicity clusters

NASA Astrophysics Data System (ADS)

Yeck, William L.; Block, Lisa V.; Wood, Christopher K.; King, Vanessa M.

2015-01-01

The Paradox Valley Unit (PVU), a salinity control project in southwest Colorado, disposes of brine in a single deep injection well. Since the initiation of injection at the PVU in 1991, earthquakes have been repeatedly induced. PVU closely monitors all seismicity in the Paradox Valley region with a dense surface seismic network. A key factor for understanding the seismic hazard from PVU injection is the maximum magnitude earthquake that can be induced. The estimate of maximum magnitude of induced earthquakes is difficult to constrain as, unlike naturally occurring earthquakes, the maximum magnitude of induced earthquakes changes over time and is affected by injection parameters. We investigate temporal variations in maximum magnitudes of induced earthquakes at the PVU using two methods. First, we consider the relationship between the total cumulative injected volume and the history of observed largest earthquakes at the PVU. Second, we explore the relationship between maximum magnitude and the geometry of individual seismicity clusters. Under the assumptions that: (i) elevated pore pressures must be distributed over an entire fault surface to initiate rupture and (ii) the location of induced events delineates volumes of sufficiently high pore-pressure to induce rupture, we calculate the largest allowable vertical penny-shaped faults, and investigate the potential earthquake magnitudes represented by their rupture. Results from both the injection volume and geometrical methods suggest that the PVU has the potential to induce events up to roughly MW 5 in the region directly surrounding the well; however, the largest observed earthquake to date has been about a magnitude unit smaller than this predicted maximum. In the seismicity cluster surrounding the injection well, the maximum potential earthquake size estimated by these methods and the observed maximum magnitudes have remained steady since the mid-2000s. These observations suggest that either these methods overpredict maximum magnitude for this area or that long time delays are required for sufficient pore-pressure diffusion to occur to cause rupture along an entire fault segment. We note that earthquake clusters can initiate and grow rapidly over the course of 1 or 2 yr, thus making it difficult to predict maximum earthquake magnitudes far into the future. The abrupt onset of seismicity with injection indicates that pore-pressure increases near the well have been sufficient to trigger earthquakes under pre-existing tectonic stresses. However, we do not observe remote triggering from large teleseismic earthquakes, which suggests that the stress perturbations generated from those events are too small to trigger rupture, even with the increased pore pressures.

Complex rupture during the 12 January 2010 Haiti earthquake

USGS Publications Warehouse

Hayes, G.P.; Briggs, R.W.; Sladen, A.; Fielding, E.J.; Prentice, C.; Hudnut, K.; Mann, P.; Taylor, F.W.; Crone, A.J.; Gold, R.; Ito, T.; Simons, M.

2010-01-01

Initially, the devastating Mw 7.0, 12 January 2010 Haiti earthquake seemed to involve straightforward accommodation of oblique relative motion between the Caribbean and North American plates along the Enriquillog-Plantain Garden fault zone. Here, we combine seismological observations, geologic field data and space geodetic measurements to show that, instead, the rupture process may have involved slip on multiple faults. Primary surface deformation was driven by rupture on blind thrust faults with only minor, deep, lateral slip along or near the main Enriquillog-Plantain Garden fault zone; thus the event only partially relieved centuries of accumulated left-lateral strain on a small part of the plate-boundary system. Together with the predominance of shallow off-fault thrusting, the lack of surface deformation implies that remaining shallow shear strain will be released in future surface-rupturing earthquakes on the Enriquillog-Plantain Garden fault zone, as occurred in inferred Holocene and probable historic events. We suggest that the geological signature of this earthquakeg-broad warping and coastal deformation rather than surface rupture along the main fault zoneg-will not be easily recognized by standard palaeoseismic studies. We conclude that similarly complex earthquakes in tectonic environments that accommodate both translation and convergenceg-such as the San Andreas fault through the Transverse Ranges of Californiag-may be missing from the prehistoric earthquake record. ?? 2010 Macmillan Publishers Limited. All rights reserved.

Coseismic rupturing stopped by Aso volcano during the 2016 Mw 7.1 Kumamoto earthquake, Japan.

PubMed

Lin, A; Satsukawa, T; Wang, M; Mohammadi Asl, Z; Fueta, R; Nakajima, F

2016-11-18

Field investigations and seismic data show that the 16 April 2016 moment magnitude (M w ) 7.1 Kumamoto earthquake produced a ~40-kilometer-long surface rupture zone along the northeast-southwest-striking Hinagu-Futagawa strike-slip fault zone and newly identified faults on the western side of Aso caldera, Kyushu Island, Japan. The coseismic surface ruptures cut Aso caldera, including two volcanic cones inside it, but terminate therein. The data show that northeastward propagation of coseismic rupturing terminated in Aso caldera because of the presence of magma beneath the Aso volcanic cluster. The seismogenic faults of the 2016 Kumamoto earthquake may require reassessment of the volcanic hazard in the vicinity of Aso volcano. Copyright © 2016, American Association for the Advancement of Science.

Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation

NASA Technical Reports Server (NTRS)

Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.

2005-01-01

We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

Apparatus for controlling fluid flow in a conduit wall

DOEpatents

Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

2003-05-13

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Effects of oxygen plasma treatment on domestic aramid fiber III reinforced bismaleimide composite interfacial properties

NASA Astrophysics Data System (ADS)

Shi, Chen; Wang, Jing; Chen, Ping; Feng, Jiayue; Cui, Jinyuan; Yang, Faze

2017-12-01

Domestic Aramid Fiber III (DAF III) was modified by oxygen plasma treatment. The fiber surface characteristics was observed by Scanning Electron Microscopy. The results showed that oxygen plasma treatment changed surface morphologies. The effects of oxygen plasma treatment on DAF III reinforced bismaleimides (BMI) composite bending and interfacial properties were investigated, respectively. The ILSS value increased from 49.3 MPa to 56.0 MPa (by 13.5%) after oxygen plasma treatment. The bending strength changed a little. Furthermore, the composite rupture mode changed from interfacial rupture to fiber or resin bulk rupture.

Complementary Ruptures of Surface Ruptures and Deep Asperity during the 2014 Northern Nagano, Japan, Earthquake (MW 6.3)

NASA Astrophysics Data System (ADS)

Asano, K.; Iwata, T.; Kubo, H.

2015-12-01

A thrust earthquake of MW 6.3 occurred along the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL) in the northern Nagano prefecture, central Japan, on November 22, 2014. This event was reported to be related to an active fault, the Kamishiro fault belonging to the ISTL (e.g., HERP, 2014). The surface rupture is observed along the Kamishiro fault (e.g., Lin et al., 2015; Okada et al., 2015). We estimated the kinematic source rupture process of this earthquake through the multiple time-window linear waveform inversion method (Hartzell and Heaton, 1983). We used velocity waveforms in 0.05-1 Hz from 12 strong motion stations of K-NET, KiK-net (NIED), JMA, and Nagano prefecture (SK-net, ERI). In order to enhance the reliability in Green's functions, we assumed one-dimensional velocity structure models different for the different stations, which were extracted from the nation-wide three-dimensional velocity structure model, Japan Integrated Velocity Structure Model (JIVSM, Koketsu et al., 2012). Considering the spatial distribution of aftershocks (Sakai et al., 2015) and surface ruptures, the assumed fault model consisted of two dip-bending fault segments with different dip angles between the northern and southern segments. The total length and width of the fault plane is 20 km and 13 km, relatively, and the fault model is divided into 260 subfaults of 1 km × 1 km in space and six smoothed ramp functions in time. An asperity or large slip area with a peak slip of 1.9 m was estimated in the lower plane of the northern segment in the approximate depth range of 4 to 8 km. The depth extent of this asperity is consistent with the seismogenic zone revealed by past studies (e.g., Panayotopoulos et al., 2014). In contrast, the slip in the southern segment is relatively concentrated in the shallow portion of the segment where the surface ruptures were found along the Kamishiro fault. The overall spatial rupture pattern of the source fault, in which the deep asperity was located on the northern segment and surface rupture was found on the southern segment, seems to be spatially consistent with the mapped active faults. These findings suggest characteristic and repeating features of fault ruptures along active faults where static offsets have accumulated over past events, and it would be a good constraint on earthquake scenarios along it.

New investigations of the October 1999 Hector Mine Earthquake surface rupture

NASA Astrophysics Data System (ADS)

Sousa, F.; Harvey, J. C.; Hudnut, K. W.; Akciz, S. O.; Stock, J. M.

2013-12-01

We report on new field and computer based investigation of the surface rupture of the October 16, 1999 Hector Mine Earthquake. In cooperation with the United States Marine Corps Air Ground Combat Center Twentynine Palms (MCAGCC), our team was allowed ground and aerial access to the extent of the surface rupture for limited times during October - December 2012. As far as we know, this was the first scientific access granted to the entire surface rupture since the immediate aftermath of the earthquake, and the first scientific access of any kind to some parts of the maximum slip zone since before the event. This locale is an excellent natural laboratory for detailed study of a major earthquake surface rupture because: 1) complete circumscription within the boundaries of MCAGCC severely limit both past and future human disruption of the rupture, particularly in the mountainous maximum slip zone; 2) groundbreaking aerial LiDAR survey carried out six months after the earthquake was followed up by a higher density, wider swath LiDAR survey in May 2012, making the temporal evolution of this rupture perhaps the most completely physically documented of any major rupture; and 3) field investigation immediately following the event was followed up by computer based offset measurements using the April 2000 LiDAR dataset, providing a database of published offset measurements. Due to time constraints imposed by MCAGGC we focused our new research effort along the ~8 km long maximum slip zone of the rupture, roughly corresponding to the zone of >4 m dextral offset. Our investigation includes 1) walking this entire section of the fault and making >30 measurements of dextral slip while photo documenting the current state of the rupture; 2) creating a difference raster for the entire 8 km maximum slip zone from exactly congruent DEM's made from the 2000 and 2012 LiDAR data sets; 3) documenting the fault traces with a Trimble GeoXH high precision handheld GPS unit (+/- 10 cm); 4) carrying out field checks of a small number of computer-based offset measurements made using the 2000 LiDAR dataset; and 5) high-resolution low-altitude (<100 m AGL) photography of the maximum slip zone during a helicopter overflight. To date, important results include 1) identification of two new maximum slip locations where features are offset 7.9 m +/- 0.5 m and 6.7 m +/- 0.5 m; 2) a database of >30 offset measurements (georeferenced and photo documented) made by our team on the ground; 3) clear changes in fracture visibility in the field, with some fractures more visible, and others no longer visible, compared to the 1999-2000 studies; and 4) examples of a few field checks that both strongly agree and disagree with computer based LiDAR offset measurements.

Analytic Study of Three-Dimensional Rupture Propagation in Strike-Slip Faulting with Analogue Models

NASA Astrophysics Data System (ADS)

Chan, Pei-Chen; Chu, Sheng-Shin; Lin, Ming-Lang

2014-05-01

Strike-slip faults are high angle (or nearly vertical) fractures where the blocks have moved along strike way (nearly horizontal). Overburden soil profiles across main faults of Strike-slip faults have revealed the palm and tulip structure characteristics. McCalpin (2005) has trace rupture propagation on overburden soil surface. In this study, we used different offset of slip sandbox model profiles to study the evolution of three-dimensional rupture propagation by strike -slip faulting. In strike-slip faults model, type of rupture propagation and width of shear zone (W) are primary affecting by depth of overburden layer (H), distances of fault slip (Sy). There are few research to trace of three-dimensional rupture behavior and propagation. Therefore, in this simplified sandbox model, investigate rupture propagation and shear zone with profiles across main faults when formation are affecting by depth of overburden layer and distances of fault slip. The investigators at the model included width of shear zone, length of rupture (L), angle of rupture (θ) and space of rupture. The surface results was follow the literature that the evolution sequence of failure envelope was R-faults, P-faults and Y-faults which are parallel to the basement fault. Comparison surface and profiles structure which were curved faces and cross each other to define 3-D rupture and width of shear zone. We found that an increase in fault slip could result in a greater width of shear zone, and proposed a W/H versus Sy/H relationship. Deformation of shear zone showed a similar trend as in the literature that the increase of fault slip resulted in the increase of W, however, the increasing trend became opposite after a peak (when Sy/H was 1) value of W was reached (small than 1.5). The results showed that the W width is limited at a constant value in 3-D models by strike-slip faulting. In conclusion, this study helps evaluate the extensions of the shear zone influenced regions for strike-slip faults.

Estimating rupture distances without a rupture

USGS Publications Warehouse

Thompson, Eric M.; Worden, Charles

2017-01-01

Most ground motion prediction equations (GMPEs) require distances that are defined relative to a rupture model, such as the distance to the surface projection of the rupture (RJB) or the closest distance to the rupture plane (RRUP). There are a number of situations in which GMPEs are used where it is either necessary or advantageous to derive rupture distances from point-source distance metrics, such as hypocentral (RHYP) or epicentral (REPI) distance. For ShakeMap, it is necessary to provide an estimate of the shaking levels for events without rupture models, and before rupture models are available for events that eventually do have rupture models. In probabilistic seismic hazard analysis, it is often convenient to use point-source distances for gridded seismicity sources, particularly if a preferred orientation is unknown. This avoids the computationally cumbersome task of computing rupture-based distances for virtual rupture planes across all strikes and dips for each source. We derive average rupture distances conditioned on REPI, magnitude, and (optionally) back azimuth, for a variety of assumed seismological constraints. Additionally, we derive adjustment factors for GMPE standard deviations that reflect the added uncertainty in the ground motion estimation when point-source distances are used to estimate rupture distances.

A preliminary study on surface ground deformation near shallow foundation induced by strike-slip faulting

NASA Astrophysics Data System (ADS)

Wong, Pei-Syuan; Lin, Ming-Lang

2016-04-01

According to investigation of recent earthquakes, ground deformation and surface rupture are used to map the influenced range of the active fault. The zones of horizontal and vertical surface displacements and different features of surface rupture are investigated in the field, for example, the Greendale Fault 2010, MW 7.1 Canterbury earthquake. The buildings near the fault rotated and displaced vertically and horizontally due to the ground deformation. Besides, the propagation of fault trace detoured them because of the higher rigidity. Consequently, it's necessary to explore the ground deformation and mechanism of the foundation induced by strike-slip faulting for the safety issue. Based on previous study from scaled analogue model of strike-slip faulting, the ground deformation is controlled by material properties, depth of soil, and boundary condition. On the condition controlled, the model shows the features of ground deformation in the field. This study presents results from shear box experiment on small-scale soft clay models subjected to strike-slip faulting and placed shallow foundations on it in a 1-g environment. The quantifiable data including sequence of surface rupture, topography and the position of foundation are recorded with increasing faulting. From the result of the experiment, first en echelon R shears appeared. The R shears rotated to a more parallel angle to the trace and cracks pulled apart along them with increasing displacements. Then the P shears crossed the basement fault in the opposite direction appears and linked R shears. Lastly the central shear was Y shears. On the other hand, the development of wider zones of rupture, higher rising surface and larger the crack area on surface developed, with deeper depth of soil. With the depth of 1 cm and half-box displacement 1.2 cm, en echelon R shears appeared and the surface above the fault trace elevated to 1.15 mm (Dv), causing a 1.16 cm-wide zone of ground-surface rupture and deformation (W). Compared to the investigation in field, rupture of the Greendale Fault, produced a 30-km-long, 300-m-wide zone of ground-surface rupture and deformation (W), involving 5.29 m maximum horizontal , 1.45 m maximum vertical (Dv, max) and 2.59 m average net displacement. Meanwhile, en echelon R shears and cracks were recorded in some region. Besides, the 400-m depth of deep sedimentation (Ds) in the Christchurch City area. Greendale Fault showed close ratio Dv/Ds and W/Ds compared to the experimental case (in the same order), which indicated the wide zone of ground-surface rupture and deformation may be normalized with the vertical displacement (Dv). The foundation located above the basement-fault trace had obvious horizontal displacements and counter-clockwise rotation with increasing displacement. Horizontal displacements and rotation decreased with deeper depth of soil. The deeper embedded foundation caused more rotation. Besides, the soil near the foundation is confined and pressed when it rotates. Key words: strike-slip fault, shallow foundation, ground deformation

The 2011 Mw 7.1 Van (Eastern Turkey) earthquake

USGS Publications Warehouse

Elliot, John R.; Copley, Alex C.; Holley, R.; Scharer, Katherine M.; Parsons, Barry

2013-01-01

We use interferometric synthetic aperture radar (InSAR), body wave seismology, satellite imagery, and field observations to constrain the fault parameters of the Mw 7.1 2011 Van (Eastern Turkey) reverse-slip earthquake, in the Turkish-Iranian plateau. Distributed slip models from elastic dislocation modeling of the InSAR surface displacements from ENVISAT and COSMO-SkyMed interferograms indicate up to 9 m of reverse and oblique slip on a pair of en echelon NW 40 °–54 ° dipping fault planes which have surface extensions projecting to just 10 km north of the city of Van. The slip remained buried and is relatively deep, with a centroid depth of 14 km, and the rupture reaching only within 8–9 km of the surface, consistent with the lack of significant ground rupture. The up-dip extension of this modeled WSW striking fault plane coincides with field observations of weak ground deformation seen on the western of the two fault segments and has a dip consistent with that seen at the surface in fault gouge exposed in Quaternary sediments. No significant coseismic slip is found in the upper 8 km of the crust above the main slip patches, except for a small region on the eastern segment potentially resulting from the Mw 5.9 aftershock on the same day. We perform extensive resolution tests on the data to confirm the robustness of the observed slip deficit in the shallow crust. We resolve a steep gradient in displacement at the point where the planes of the two fault segments ends are inferred to abut at depth, possibly exerting some structural control on rupture extent.

The 1959 MW 7.3 Hebgen Lake earthquake revisited: morphology and mechanics from lidar

NASA Astrophysics Data System (ADS)

Johnson, K. L.; Nissen, E.; Lajoie, L. J.

2016-12-01

This study demonstrates how we can glean new information by revisiting an early instrumental earthquake with high-resolution topography and modern thinking about the mechanics of surface rupturing. The 1959 MW 7.3 Hebgen Lake earthquake is among the largest and most deadly historic earthquakes within the conterminous United States outside of California, and one of the largest normal faulting earthquakes on record globally. The earthquake ruptured the subparallel Hebgen and Red Canyon faults within the slowly extending ( 3 mm/yr) Centennial Mountain Belt, and is one of the first to be field mapped in detail, modeled from global seismograms, and surveyed geodetically. Here, we augment these early studies with an investigation of the surface rupture in its current state. We use a 50 cm-resolution airborne lidar digital terrain model collected by the National Center for Airborne Laser Mapping (NCALM) in 2014 to document the fault scarp morphology, constrain its evolution, and speculate on the mechanical rupture properties. Using a dense set of scarp profiles, we add >400 displacement measurements to the 143 published data points from early field work, allowing more rigorous quantification of along-strike slip variability and strain gradients. Evidence of off-fault deformation is sparse along most of the scarp, though damage zone width increases where the earthquake ruptured closely spaced sedimentary contacts rather than unconsolidated Quaternary deposits. In a few places, we can identify composite scarps from which we estimate the number of earthquakes that have offset Holocene surfaces. We assess the scarp's degraded state, including some sites that were surveyed in 1980 and 2009 and others that have not been revisited since the initial investigation. Where the rupture crosses unconsolidated surfaces, we compute local sediment diffusion coefficients and analyze their variability along strike. Lastly, we model subsurface fault geometry by fitting dipping planes to its surface trace, testing our best-fit fault dips against those recovered in seismic analyses; this reaffirms that both main rupture strands correspond to primary faulting rather than induced landsliding.

Rupture Following Biceps-to-Triceps Tendon Transfer in Adolescents and Young Adults With Spinal Cord Injury:

PubMed Central

Merenda, Lisa A.; Rutter, Laure; Curran, Kimberly; Kozin, Scott H.

2012-01-01

Background: Tendon transfer surgery can restore elbow extension in approximately 70% of persons with tetraplegia and often results in antigravity elbow extension strength. However, we have noted an almost 15% rupture/attenuation rate. Objective: This investigation was conducted to analyze potential causes in adolescents/young adults with spinal cord injury (SCI) who experienced tendon rupture or attenuation after biceps-to-triceps transfer. Methods: Medical charts of young adults with SCI who underwent biceps-to-triceps transfer and experienced tendon rupture or attenuation were reviewed. Data collected by retrospective chart review included general demographics, surgical procedure(s), use and duration of antibiotic treatment, time from tendon transfer surgery to rupture/attenuation, and method of diagnosis. Results: Twelve subjects with tetraplegia (mean age, 19 years) who underwent biceps-to-triceps reconstruction with subsequent tendon rupture or attenuation were evaluated. Mean age at time of tendon transfer was 18 years (range, 14-21 years). A fluoroquinolone was prescribed for 42% (n=5) of subjects. Tendon rupture was noted in 67% (n=8), and attenuation was noted in 33% (n=4). Average length of time from surgery to tendon rupture/attenuation was 5.7 months (range, 3-10 months). Conclusion: Potential contributing causes of tendon rupture/attenuation after transfer include surgical technique, rehabilitation, co-contraction of the transfer, poor patient compliance, and medications. In this cohort, 5 subjects were prescribed fluoroquinolones that have a US Food and Drug Administration black box concerning tendon ruptures. Currently, all candidates for upper extremity tendon transfer reconstruction are counseled on the effects of fluoroquinolones and the potential risk for tendon rupture. PMID:23459326

Fine-scale delineation of the location of and relative ground shaking within the San Andreas Fault zone at San Andreas Lake, San Mateo County, California

USGS Publications Warehouse

Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Prentice, C.S.; Sickler, R.R.

2013-01-01

The San Francisco Public Utilities Commission is seismically retrofitting the water delivery system at San Andreas Lake, San Mateo County, California, where the reservoir intake system crosses the San Andreas Fault (SAF). The near-surface fault location and geometry are important considerations in the retrofit effort. Because the SAF trends through highly distorted Franciscan mélange and beneath much of the reservoir, the exact trace of the 1906 surface rupture is difficult to determine from surface mapping at San Andreas Lake. Based on surface mapping, it also is unclear if there are additional fault splays that extend northeast or southwest of the main surface rupture. To better understand the fault structure at San Andreas Lake, the U.S. Geological Survey acquired a series of seismic imaging profiles across the SAF at San Andreas Lake in 2008, 2009, and 2011, when the lake level was near historical lows and the surface traces of the SAF were exposed for the first time in decades. We used multiple seismic methods to locate the main 1906 rupture zone and fault splays within about 100 meters northeast of the main rupture zone. Our seismic observations are internally consistent, and our seismic indicators of faulting generally correlate with fault locations inferred from surface mapping. We also tested the accuracy of our seismic methods by comparing our seismically located faults with surface ruptures mapped by Schussler (1906) immediately after the April 18, 1906 San Francisco earthquake of approximate magnitude 7.9; our seismically determined fault locations were highly accurate. Near the reservoir intake facility at San Andreas Lake, our seismic data indicate the main 1906 surface rupture zone consists of at least three near-surface fault traces. Movement on multiple fault traces can have appreciable engineering significance because, unlike movement on a single strike-slip fault trace, differential movement on multiple fault traces may exert compressive and extensional stresses on built structures within the fault zone. Such differential movement and resulting distortion of built structures appear to have occurred between fault traces at the gatewell near the southern end of San Andreas Lake during the 1906 San Francisco earthquake (Schussler, 1906). In addition to the three fault traces within the main 1906 surface rupture zone, our data indicate at least one additional fault trace (or zone) about 80 meters northeast of the main 1906 surface rupture zone. Because ground shaking also can damage structures, we used fault-zone guided waves to investigate ground shaking within the fault zones relative to ground shaking outside the fault zones. Peak ground velocity (PGV) measurements from our guided-wave study indicate that ground shaking is greater at each of the surface fault traces, varying with the frequency of the seismic data and the wave type (P versus S). S-wave PGV increases by as much as 5–6 times at the fault traces relative to areas outside the fault zone, and P-wave PGV increases by as much as 3–10 times. Assuming shaking increases linearly with increasing earthquake magnitude, these data suggest strong shaking may pose a significant hazard to built structures that extend across the fault traces. Similarly complex fault structures likely underlie other strike-slip faults (such as the Hayward, Calaveras, and Silver Creek Faults) that intersect structures of the water delivery system, and these fault structures similarly should be investigated.

Crack initiation and propagation in 50.9 at. pct Ni-Ti pseudoelastic shape-memory wires in bending-rotation fatigue

NASA Astrophysics Data System (ADS)

Sawaguchi, Tak Ahiro; Kausträter, Gregor; Yawny, Alejandro; Wagner, Martin; Eggeler, Gunther

2003-12-01

The structural fatigue of pseudoelastic Ni-Ti wires (50.9 at. pct Ni) was investigated using bending-rotation fatigue (BRF) tests, where a bent and otherwise unconstrained wire was forced to rotate at different rotational speeds. The number of cycles to failure ( N f ) was measured for different bending radii and wire thicknesses (1.0, 1.2, and 1.4 mm). The wires consisted of an alloy with a 50-nm grain size, no precipitates, and some TiC inclusions. In BRF tests, the surface of the wire is subjected to tension-compression cycles, and fatigue lives can be related to the maximum tension and compression strain amplitudes ( ɛ a ) in the wire surface. The resulting ɛ a - N f curves can be subdivided into three regimes. At ɛ a > 1 pct rupture occurs early (low N f ) and the fatigue-rupture characteristics were strongly dependent on ɛ a and the rotational speed (regime 1). For 0.75 pct < ɛ a < 1 pct, fatigue lives strongly increase and are characterized by a significant statistical scatter (regime 2). For ɛ a < 0.75 pct, no fatigue rupture occurs up to cycle numbers of 106 (regime 3). Using scanning electron microscopy (SEM), it was shown that surface cracks formed in regions with local stress raisers (such as inclusions and/or scratches). The growth of surface cracks during fatigue loading produced striations on the rupture surface; during final rupture, ductile voids form. The microstructural details of fatigue-damage accumulation during BRF testing are described and discussed.

Surface rupture and slip distribution of the 2016 Mw7.8 Kaikoura earthquake (New Zealand) from optical satellite image correlation using MicMac

NASA Astrophysics Data System (ADS)

Champenois, Johann; Klinger, Yann; Grandin, Raphaël; Satriano, Claudio; Baize, Stéphane; Delorme, Arthur; Scotti, Oona

2017-04-01

Remote sensing techniques, like optical satellite image correlation, are very efficient methods to localize and quantify surface displacements due to earthquakes. In this study, we use the french sub-pixel correlator MicMac (Multi Images Correspondances par Méthodes Automatiques de Corrélation). This free open-source software, developed by IGN, was recently adapted to process satellite images. This correlator uses regularization, and that provides good results especially in near-fault area with a high spatial resolution. We use co-seismic pair of ortho-images to measure the horizontal displacement field during the recent 2016 Mw7.8 Kaikoura earthquake. Optical satellite images from different satellites are processed (Sentinel-2A, Landsat8, etc.) to present a dense map of the surface ruptures and to analyze high density slip distribution along all major ruptures. We also provide a detail pattern of deformation along these main surface ruptures. Moreover, 2D displacement from optical correlation is compared to co-seismic measurements from GPS, static displacement from accelerometric records, geodetic marks and field investigations. Last but not least, we investigate the reconstruction of 3D displacement from combining InSAR, GPS and optic.

Verification of SORD, and Application to the TeraShake Scenario

NASA Astrophysics Data System (ADS)

Ely, G. P.; Day, S.; Minster, J.

2007-12-01

The Support Operator Rupture Dynamics (SORD) code provides a highly scalable (up to billions of nodes) computational tool for modeling spontaneous rupture on a non-planar fault surface embedded in a heterogeneous medium with surface topography. SORD successfully performs the SCEC Rupture Dynamics Code Validation Project tests, and we have undertaken further dynamic rupture tests assessing the effects of distorted hexahedral meshes on code accuracy. We generate a family of distorted meshes by simple shearing (applied both parallel and normal to the fault plane) of an initially Cartesian mesh. For shearing normal to the fault, shearing angle was varied, up to a maximum of 73-degrees. For SCEC Validation Problem 3, grid-induced errors increase with mesh-shear angle, with the logarithm of error approximately proportional to angle over the range tested. At 73-degrees, RMS misfits are about 10% for peak slip rate, and 0.5% for both rupture time and total slip, indicating that the method--which up to now we have applied mainly to near-vertical strike-slip faulting-- also is capable of handling geometries appropriate to low-angle surface-rupturing thrust earthquakes. The SORD code was used to reexamine the TeraShake 2 dynamics simulations of a M7.7 earthquake on the southern San Andreas Fault. Relative to the original (Olsen et al, 2007) TeraShake 2 simulations, our spontaneous rupture models find decreased peak ground velocities in the Los Angles basin, principally due to a shallower eastward connecting basin chain in the SCEC Velocity Model Version 4 (used in our simulations) compared to Version 3 (used by Olsen et al.). This is partially offset by including the effects of surface topography (which was not included in the Olsen et al. models) in the simulation, which increases PGV at some basin sites by as much as a factor of two. Some non-basin sites showed comparable decreases in PGV. These predicted topographic effects are quite large, so it is important to quantify SORD accuracy in the presence of non-planar free surface geometry. We test the case of a semi-circular canyon to an incident P wave, and find close agreement with boundary element methods, for surface amplification at wavelengths comparable to the canyon width.

An insight on correlations between kinematic rupture parameters from dynamic ruptures on rough faults

NASA Astrophysics Data System (ADS)

Thingbijam, Kiran Kumar; Galis, Martin; Vyas, Jagdish; Mai, P. Martin

2017-04-01

We examine the spatial interdependence between kinematic parameters of earthquake rupture, which include slip, rise-time (total duration of slip), acceleration time (time-to-peak slip velocity), peak slip velocity, and rupture velocity. These parameters were inferred from dynamic rupture models obtained by simulating spontaneous rupture on faults with varying degree of surface-roughness. We observe that the correlations between these parameters are better described by non-linear correlations (that is, on logarithm-logarithm scale) than by linear correlations. Slip and rise-time are positively correlated while these two parameters do not correlate with acceleration time, peak slip velocity, and rupture velocity. On the other hand, peak slip velocity correlates positively with rupture velocity but negatively with acceleration time. Acceleration time correlates negatively with rupture velocity. However, the observed correlations could be due to weak heterogeneity of the slip distributions given by the dynamic models. Therefore, the observed correlations may apply only to those parts of rupture plane with weak slip heterogeneity if earthquake-rupture associate highly heterogeneous slip distributions. Our findings will help to improve pseudo-dynamic rupture generators for efficient broadband ground-motion simulations for seismic hazard studies.

Insight into the rupture process of a rare tsunami earthquake from near-field high-rate GPS

NASA Astrophysics Data System (ADS)

Macpherson, K. A.; Hill, E. M.; Elosegui, P.; Banerjee, P.; Sieh, K. E.

2011-12-01

We investigated the rupture duration and velocity of the October 25, 2010 Mentawai earthquake by examining high-rate GPS displacement data. This Mw=7.8 earthquake appears to have ruptured either an up-dip part of the Sumatran megathrust or a fore-arc splay fault, and produced tsunami run-ups on nearby islands that were out of proportion with its magnitude. It has been described as a so-called "slow tsunami earthquake", characterised by a dearth of high-frequency signal and long rupture duration in low-strength, near-surface media. The event was recorded by the Sumatran GPS Array (SuGAr), a network of high-rate (1 sec) GPS sensors located on the nearby islands of the Sumatran fore-arc. For this study, the 1 sec time series from 8 SuGAr stations were selected for analysis due to their proximity to the source and high-quality recordings of both static displacements and dynamic waveforms induced by surface waves. The stations are located at epicentral distances of between 50 and 210 km, providing a unique opportunity to observe the dynamic source processes of a tsunami earthquake from near-source, high-rate GPS. We estimated the rupture duration and velocity by simulating the rupture using the spectral finite-element method SPECFEM and comparing the synthetic time series to the observed surface waves. A slip model from a previous study, derived from the inversion of GPS static offsets and tsunami data, and the CRUST2.0 3D velocity model were used as inputs for the simulations. Rupture duration and velocity were varied for a suite of simulations in order to determine the parameters that produce the best-fitting waveforms.

Dynamic ruptures on faults of complex geometry: insights from numerical simulations, from large-scale curvature to small-scale fractal roughness

NASA Astrophysics Data System (ADS)

Ulrich, T.; Gabriel, A. A.

2016-12-01

The geometry of faults is subject to a large degree of uncertainty. As buried structures being not directly observable, their complex shapes may only be inferred from surface traces, if available, or through geophysical methods, such as reflection seismology. As a consequence, most studies aiming at assessing the potential hazard of faults rely on idealized fault models, based on observable large-scale features. Yet, real faults are known to be wavy at all scales, their geometric features presenting similar statistical properties from the micro to the regional scale. The influence of roughness on the earthquake rupture process is currently a driving topic in the computational seismology community. From the numerical point of view, rough faults problems are challenging problems that require optimized codes able to run efficiently on high-performance computing infrastructure and simultaneously handle complex geometries. Physically, simulated ruptures hosted by rough faults appear to be much closer to source models inverted from observation in terms of complexity. Incorporating fault geometry on all scales may thus be crucial to model realistic earthquake source processes and to estimate more accurately seismic hazard. In this study, we use the software package SeisSol, based on an ADER-Discontinuous Galerkin scheme, to run our numerical simulations. SeisSol allows solving the spontaneous dynamic earthquake rupture problem and the wave propagation problem with high-order accuracy in space and time efficiently on large-scale machines. In this study, the influence of fault roughness on dynamic rupture style (e.g. onset of supershear transition, rupture front coherence, propagation of self-healing pulses, etc) at different length scales is investigated by analyzing ruptures on faults of varying roughness spectral content. In particular, we investigate the existence of a minimum roughness length scale in terms of rupture inherent length scales below which the rupture ceases to be sensible. Finally, the effect of fault geometry on ground-motions, in the near-field, is considered. Our simulations feature a classical linear slip weakening on the fault and a viscoplastic constitutive model off the fault. The benefits of using a more elaborate fast velocity-weakening friction law will also be considered.

Quaternary Slip History for the Agua Blanca Fault, northern Baja California, Mexico

NASA Astrophysics Data System (ADS)

Gold, P. O.; Behr, W. M.; Rockwell, T. K.; Fletcher, J. M.

2017-12-01

The Agua Blanca Fault (ABF) is the primary structure accommodating San Andreas-related right-lateral slip across the Peninsular Ranges of northern Baja California. Activity on this fault influences offshore faults that parallel the Pacific coast from Ensenada to Los Angeles and is a potential threat to communities in northern Mexico and southern California. We present a detailed Quaternary slip history for the ABF, including new quantitative constraints on geologic slip rates, slip-per-event, the timing of most recent earthquake, and the earthquake recurrence interval. Cosmogenic 10Be exposure dating of clasts from offset fluvial geomorphic surfaces at 2 sites located along the western, and most active, section of the ABF yield preliminary slip rate estimates of 2-4 mm/yr and 3 mm/yr since 20 ka and 2 ka, respectively. Fault zone geomorphology preserved at the younger site provides evidence for right-lateral surface displacements measuring 2.5 m in the past two ruptures. Luminescence dating of an offset alluvial fan at a third site is in progress, but is expected to yield a slip rate relevant to the past 10 kyr. Adjacent to this third site, we excavated 2 paleoseismic trenches across a sag pond formed by a right step in the fault. Preliminary radiocarbon dates indicate that the 4 surface ruptures identified in the trenches occurred in the past 6 kyr, although additional dating should clarify earthquake timing and the mid-Holocene to present earthquake recurrence interval, as well as the likely date of the most recent earthquake. Our new slip rate estimates are somewhat lower than, but comparable within error to, previous geologic estimates based on soil morphology and geodetic estimates from GPS, but the new record of surface ruptures exposed in the trenches is the most complete and comprehensively dated earthquake history yet determined for this fault. Together with new and existing mapping of tectonically generated geomorphology along the ABF, our constraints show that contrary to some theories of fault interaction and activity for this section of the San Andreas system, the Agua Blanca Fault has been active over the late Holocene, and should be considered as a potential source of seismic hazard.

Coseismic surface displacements from optical and SAR image offset tracking, fault modeling and geomorphological analysis of the Sept. 24th, 2013 M7.7 Balochistan earthquake

NASA Astrophysics Data System (ADS)

Harrington, Jonathan; Wang, Teng; Feng, Guangcai; Akoglu, Ahmet; Jónsson, Sigurjón; Motagh, Mahdi

2014-05-01

The M 7.7 earthquake in the Balochistan province of Pakistan on September 24th, 2013 took place along a subsidiary fault in the transition area between the Makran accretionary prism and the Chaman transform fault. This tectonics of the Indian and Arabian plate collisions with Eurasia produce primarily oblique left-lateral strike slip in this region. In this work, measurements of displacement and mapping of the rupture trace are achieved through image correlation of Landsat 8 images and SAR offset tracking of TerraSAR-X data. Horizontal displacements from both methods and derived vertical displacements are used to constrain a fault rupture model for the earthquake. Preliminary results show a surprisingly uniform slip distribution with maximum displacement near the surface. The total fault rupture length is ~210 km, with up to 9 m of left-lateral strike-slip and 3 m of reverse faulting. Additionally, mapping of the rupture trace is made use of for geomorphological observations relating to slip rates and identification of transpressional and transtensional features. Our results indicate a mostly smooth rupture trace, with the presence of two restraining steps, a releasing bend and a 3 km long sliver where the surface rupture jumped from the foot of the range-front into the alluvial fans at their base. A small block at one of the restraining steps shows intermediate displacement in both data sets. At the southern end of the rupture we observe that displacement from the earthquake cuts across a fold-and-thrust belt of the Makran accretionary prism. Preliminary results show a minimum of 12 km of repeated section of the accretionary wedge, and within the southern repeated section we find an offset of 600 m between two parallel ridges across the rupture trace. We relate these observations to conceptual models of fault segmentation and growth.

Broadband Rupture Process of the 2001 Kunlun Fault (Mw 7.8) Earthquake

NASA Astrophysics Data System (ADS)

Antolik, M.; Abercrombie, R.; Ekstrom, G.

2003-04-01

We model the source process of the 14 November, 2001 Kunlun fault earthquake using broadband body waves from the Global Digital Seismographic Network (P, SH) and both point-source and distributed slip techniques. The point-source mechanism technique is a non-linear iterative inversion that solves for focal mechanism, moment rate function, depth, and rupture directivity. The P waves reveal a complex rupture process for the first 30 s, with smooth unilateral rupture toward the east along the Kunlun fault accounting for the remainder of the 120 s long rupture. The obtained focal mechanism for the main portion of the rupture is (strike=96o, dip=83o, rake=-8o) which is consistent with both the Harvard CMT solution and observations of the surface rupture. The seismic moment is 5.29×1020 Nm and the average rupture velocity is ˜3.5 km/s. However, the initial portion of the P waves cannot be fit at all with this mechanism. A strong pulse visible in the first 20 s can only be matched with an oblique-slip subevent (MW ˜ 6.8-7.0) involving a substantial normal faulting component, but the nodal planes of this mechanism are not well constrained. The first-motion polarities of the P waves clearly require a strike mechanism with a similar orientation as the Kunlun fault. Field observations of the surface rupture (Xu et al., SRL, 73, No. 6) reveal a small 26 km-long strike-slip rupture at the far western end (90.5o E) with a 45-km long gap and extensional step-over between this rupture and the main Kunlun fault rupture. We hypothesize that the initial fault break occurred on this segment, with release of the normal faulting energy as a continuous rupture through the extensional step, enabling transfer of the slip to the main Kunlun fault. This process is similar to that which occurred during the 2002 Denali fault (MW 7.9) earthquake sequence except that 11 days elapsed between the October 23 (M_W 6.7) foreshock and the initial break of the Denali earthquake along a thrust fault.

Geologic and structural controls on rupture zone fabric: A field-based study of the 2010 Mw 7.2 El Mayor–Cucapah earthquake surface rupture

USGS Publications Warehouse

Teran, Orlando; Fletcher, John L.; Oskin, Michael; Rockwell, Thomas; Hudnut, Kenneth W.; Spelz, Ronald; Akciz, Sinan; Hernandez-Flores, Ana Paula; Morelan, Alexander

2015-01-01

We systematically mapped (scales >1:500) the surface rupture of the 4 April 2010 Mw (moment magnitude) 7.2 El Mayor-Cucapah earthquake through the Sierra Cucapah (Baja California, northwestern Mexico) to understand how faults with similar structural and lithologic characteristics control rupture zone fabric, which is here defined by the thickness, distribution, and internal configuration of shearing in a rupture zone. Fault zone thickness and master fault dip are strongly correlated with many parameters of rupture zone fabric. Wider fault zones produce progressively wider rupture zones and both of these parameters increase systematically with decreasing dip of master faults, which varies from 20° to 90° in our dataset. Principal scarps that accommodate more than 90% of the total coseismic slip in a given transect are only observed in fault sections with narrow rupture zones (<25 m). As rupture zone thickness increases, the number of scarps in a given transect increases, and the scarp with the greatest relative amount of coseismic slip decreases. Rupture zones in previously undeformed alluvium become wider and have more complex arrangements of secondary fractures with oblique slip compared to those with pure normal dip-slip or pure strike-slip. Field relations and lidar (light detection and ranging) difference models show that as magnitude of coseismic slip increases from 0 to 60 cm, the links between kinematically distinct fracture sets increase systematically to the point of forming a throughgoing principal scarp. Our data indicate that secondary faults and penetrative off-fault strain continue to accommodate the oblique kinematics of coseismic slip after the formation of a thoroughgoing principal scarp. Among the widest rupture zones in the Sierra Cucapah are those developed above buried low angle faults due to the transfer of slip to widely distributed steeper faults, which are mechanically more favorably oriented. The results from this study show that the measureable parameters that define rupture zone fabric allow for testing hypotheses concerning the mechanics and propagation of earthquake ruptures, as well as for siting and designing facilities to be constructed in regions near active faults.

Earthquake behavior of the Enriquillo fault zone, Haiti revealed by interactive terrain visualization

NASA Astrophysics Data System (ADS)

Cowgill, E.; Bernardin, T. S.; Oskin, M. E.; Bowles, C. J.; Yikilmaz, M. B.; Kreylos, O.; Elliott, A. J.; Bishop, M. S.; Gold, R. D.; Morelan, A.; Bawden, G. W.; Hamann, B.; Kellogg, L. H.

2010-12-01

The Mw 7.0 January 12, 2010 Haiti earthquake ended 240 years of relative quiescence following earthquakes that destroyed Port-au-Prince in 1751 and 1770. We place the 2010 rupture in the context of past earthquakes and future hazards by using remote analysis of airborne LiDAR to observe the topographic expression of active faulting and develop a new conceptual model for the earthquake behavior of the eastern Enriquillo fault zone (EFZ). In this model, the 2010 event occupies a long-lived segment boundary at a stepover within the EFZ separating fault segments that likely ruptured in 1751 and 1770, explaining both past clustering and the lack of 2010 surface rupture. Immediately following the 2010 earthquake, an airborne LiDAR point cloud containing over 2.7 billion point measurements of surface features was collected by the Rochester Inst. of Technology. To analyze these data, we capitalize on the human capacity to visually identify meaningful patterns embedded in noisy data by conducting interactive visual analysis of the entire 66.8 GB Haiti terrain data in a 4-sided, 800 ft3 immersive virtual-reality environment at the UC Davis KeckCAVES using the software tools LiDAR Viewer (to analyze point cloud data) and Crusta (for 3D surficial geologic mapping on DEM data). We discovered and measured landforms displaced by past surface-rupturing earthquakes and remotely characterized the regional fault geometry. Our analysis of the ~50 km long reach of EFZ spanning the 2010 epicenter indicates that geomorphic evidence of active faulting is clearer east of the epicenter than to the west. West of the epicenter, and in the region of the 2010 rupture, the fault is poorly defined along an embayed, low-relief range front, with little evidence of recent surface rupture. In contrast, landform offsets of 6 to 50 m along the reach of the EFZ east of the epicenter and closest to Port-au-Prince attest to repeated recent surface-rupturing earthquakes here. Specifically, we found and documented offset landforms including fluvial terrace risers near Dumay (6.3 +0.9/-1.3 m) and Chauffard/Jameau (32.2 +1.8/-3.1 m), a channel (52 +18/-13 m) ~500 m east of the Chauffard/Jameau site, and an alluvial fan near Fayette (8.6 +2.8/-2.5 m). Based on the fault-trace morphology and distribution of sites where we see 6-8 m offsets, we estimate the probable along-strike extent of past surface rupture was 40 to 60 km along this fault reach. Application of moment-rupture area relationships to these observations suggest that an earthquake similar to, or larger than the Mw 7.0 2010 event is possible along the Enriquillo fault near Port-au-Prince. We deduce that the 2010 earthquake was a relatively small event on a boundary between fault segments that ruptured in 1751 and 1770, based on new analysis of historical damage reports and the gap of well-defined fault-zone morphology where the 2010 earthquake occurred.

Source rupture process of the 2016 Kaikoura, New Zealand earthquake estimated from the kinematic waveform inversion of strong-motion data

NASA Astrophysics Data System (ADS)

Zheng, Ao; Wang, Mingfeng; Yu, Xiangwei; Zhang, Wenbo

2018-03-01

On 2016 November 13, an Mw 7.8 earthquake occurred in the northeast of the South Island of New Zealand near Kaikoura. The earthquake caused severe damages and great impacts on local nature and society. Referring to the tectonic environment and defined active faults, the field investigation and geodetic evidence reveal that at least 12 fault sections ruptured in the earthquake, and the focal mechanism is one of the most complicated in historical earthquakes. On account of the complexity of the source rupture, we propose a multisegment fault model based on the distribution of surface ruptures and active tectonics. We derive the source rupture process of the earthquake using the kinematic waveform inversion method with the multisegment fault model from strong-motion data of 21 stations (0.05-0.35 Hz). The inversion result suggests the rupture initiates in the epicentral area near the Humps fault, and then propagates northeastward along several faults, until the offshore Needles fault. The Mw 7.8 event is a mixture of right-lateral strike and reverse slip, and the maximum slip is approximately 19 m. The synthetic waveforms reproduce the characteristics of the observed ones well. In addition, we synthesize the coseismic offsets distribution of the ruptured region from the slips of upper subfaults in the fault model, which is roughly consistent with the surface breaks observed in the field survey.

High Frequency Near-Field Ground Motion Excited by Strike-Slip Step Overs

NASA Astrophysics Data System (ADS)

Hu, Feng; Wen, Jian; Chen, Xiaofei

2018-03-01

We performed dynamic rupture simulations on step overs with 1-2 km step widths and present their corresponding horizontal peak ground velocity distributions in the near field within different frequency ranges. The rupture speeds on fault segments are determinant in controlling the near-field ground motion. A Mach wave impact area at the free surface, which can be inferred from the distribution of the ratio of the maximum fault-strike particle velocity to the maximum fault-normal particle velocity, is generated in the near field with sustained supershear ruptures on fault segments, and the Mach wave impact area cannot be detected with unsustained supershear ruptures alone. Sub-Rayleigh ruptures produce stronger ground motions beyond the end of fault segments. The existence of a low-velocity layer close to the free surface generates large amounts of high-frequency seismic radiation at step over discontinuities. For near-vertical step overs, normal stress perturbations on the primary fault caused by dipping structures affect the rupture speed transition, which further determines the distribution of the near-field ground motion. The presence of an extensional linking fault enhances the near-field ground motion in the extensional regime. This work helps us understand the characteristics of high-frequency seismic radiation in the vicinities of step overs and provides useful insights for interpreting the rupture speed distributions derived from the characteristics of near-field ground motion.

Ceramic Life Prediction Methodology.

DTIC Science & Technology

1986-03-01

stress rupture data were collected on two materials, a sintered silicon nitride and a lithium-aluminum-silicate. The fast fracture data was presented...graphically in the form of Weibull plots of percent failed versus failure stress . The stress rupture results were presented in tabular form. Photo...micrographs were presented to illustrate the fracture surfaces of fast fracture and stress rupture failures. A program of specimen development was coaducted

Complex Channel Avulsion in the Meghna River Foodplain During the Mid to Late Holocene: The Potential Effect of Tectonic and Co-Seismic Uplift

NASA Astrophysics Data System (ADS)

Dunham, A.; Grall, C.; Mondal, D. R.; Steckler, M. S.; Rajapara, H.; Kumar, B.; Philibosian, B.; Akhter, S. H.; Singhvi, A. K.

2016-12-01

Channel migrations and river avulsions in deltaic river systems are mainly driven by differential changes of surface topography, such as the superelevation of channels due to sedimentation. In addition to such autocyclic processes, tectonic events, such as earthquakes, may also lead to avulsions from sudden uplift. The eastern part of the Ganges-Brahmaputra-Meghna Delta (GBMD) is underlain by the blind megathrust of the IndoBurma subduction zone. In this region we investigate a 100 km long sinuous abandoned channel of the Meghna River. Immediately south of the channel, it has been previously shown that the topography is slightly higher than on the rest of the Delta and there is an oxidized Holocene exposure surface. Part of the Titas River flows northward from this area into the abandoned channel belt, opposite of the southward flowing rivers of the delta. We provide results from a detailed investigation of this abandoned channel of the Meghna River using stratigraphic logs of hand-drilled wells, resistivity profiles, sediment analyses and OSL and C14 dating, The OSL ages to be presented constrain the possible date of the event. We employ numerical modeling to evaluate the hypothesis that the co-seismic uplift associated to an earthquake can trigger the channel migration. Our modeling approach aims to estimate the co-seismic uplift associated with potential seismic events using an elastic Coulomb's dislocation model. The geometry fault in our model is estimated using geologic and GPS constraints with standard elastic parameters (Young's modulus = 80 GPa; Poisson's ratio = 0.3). We explored different potential earthquakes geometries that involve the megathrust, a splay fault, or the megathrust terminating in the splay. The magnitude and distribution of co-seismic slip are also varied between a rupture length of 112.5km and 180km along a 225km long fault. We show that any class of models can produce the amount of uplift (1-2 m) necessary for triggering the river avulsion. Thus the avulsion could be due to a >M8 megathrust earthquake or a M7 splay fault rupture. In either case, the rupture cannot extend west of the abandoned channel to the current Meghna River, and thus did not rupture to the deformation front, where the megacity of Dhaka now lies.

The Constantine (northeast Algeria) earthquake of October 27, 1985: surface ruptures and aftershock study

NASA Astrophysics Data System (ADS)

Bounif, A.; Haessler, H.; Meghraoui, M.

1987-10-01

An earthquake of magnitude Ms = 6.0 (CSEM, Strasbourg) occurred at Constantine (Algeria) on 27 October 1985. This seismic event is the strongest felt in the Tellian Atlas since the El Asnam seismic crisis of October 10, 1980. A team from the Centre de Recherche d'Astronomie, d'Astrophysique et de Géophysique (CRAAG, Algeria), utilising 8 portable stations, registered the activity a few days after the main shock. The aftershocks follow a N045° direction, and show the existence of three ruptured segments. Cross sections display a remarkable vertical fault plane and suggest asperities in the rupture process. Surface breaks were found affecting Quaternary deposits. The principal segment is about 3.8 km long showing “enéchelon” cracks with left-lateral displacement while the main direction of the rupture is N055°. Although the vertical motion is small, the northwestern block shows a normal component of the main surface faulting, while the left-lateral displacement is about 10 cm. The strike-slip focal mechanism solution determined from the global seismic network and field observations are in good agreement.

Droplet size effects on film drainage between droplet and substrate.

PubMed

Steinhaus, Benjamin; Spicer, Patrick T; Shen, Amy Q

2006-06-06

When a droplet approaches a solid surface, the thin liquid film between the droplet and the surface drains until an instability forms and then ruptures. In this study, we utilize microfluidics to investigate the effects of film thickness on the time to film rupture for water droplets in a flowing continuous phase of silicone oil deposited on solid poly(dimethylsiloxane) (PDMS) surfaces. The water droplets ranged in size from millimeters to micrometers, resulting in estimated values of the film thickness at rupture ranging from 600 nm down to 6 nm. The Stefan-Reynolds equation is used to model film drainage beneath both millimeter- and micrometer-scale droplets. For millimeter-scale droplets, the experimental and analytical film rupture times agree well, whereas large differences are observed for micrometer-scale droplets. We speculate that the differences in the micrometer-scale data result from the increases in the local thin film viscosity due to confinement-induced molecular structure changes in the silicone oil. A modified Stefan-Reynolds equation is used to account for the increased thin film viscosity of the micrometer-scale droplet drainage case.

Hemorrhagic shock as a sequela of splenic rupture in a patient with infectious mononucleosis: focus on the potential role of salicylates.

PubMed

Bouliaris, Konstantinos; Karangelis, Dimos; Daskalopoulos, Marios; Spanos, Konstantinos; Fanariotis, Michael; Giaglaras, Anargyros

2012-01-01

Despite the fact that the vast majority of splenic ruptures are traumatic, infectious mononucleosis has been incriminated as a major predisposing factor that affects the integrity of the spleen, thus causing atraumatic ruptures and life-threatening hemorrhages. Herein we present a case of a 23-year-old Caucasian male who underwent an emergency laparotomy for acute abdomen and hemorrhagic shock, caused by spontaneous splenic rupture secondary to infectious mononucleosis. The potential role of salicylates in the development of a hemorrhagic complication in a patient with infectious mononucleosis is discussed.

Single Molecule Junctions: A Laboratory for Chemistry, Mechanics and Bond Rupture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hybertsen M. S.

Simultaneous measurement [1] of junction conductance and sustained force in single molecule junctions bridging metal electrodes provides a powerful tool in the quantitative study of the character of molecule-metal bonds. In this talk I will discuss three topics. First, I will describe chemical trends in link bond strength based on experiments and Density Functional Theory based calculations. Second, I will focus on the specific case of pyridine-linked junctions. Bond rupture from the high conductance junction structure shows a requires a force that exceeds the rupture force of gold point contacts and clearly indicates the role of additional forces, beyond themore » specific N-Au donor acceptor bond. DFT-D2 calculations with empirical addition of dispersion interactions illustrates the interplay between the donor-acceptor bonding and the non-specific van der Waals interactions between the pyridine rings and Au asperities. Third, I will describe recent efforts to characterize the diversity of junction structures realized in break-junction experiments with suitable models for the potential surfaces that are observed. [1] Venkataraman Group, Columbia University.« less

Rapid Estimates of Rupture Extent for Large Earthquakes Using Aftershocks

NASA Astrophysics Data System (ADS)

Polet, J.; Thio, H. K.; Kremer, M.

2009-12-01

The spatial distribution of aftershocks is closely linked to the rupture extent of the mainshock that preceded them and a rapid analysis of aftershock patterns therefore has potential for use in near real-time estimates of earthquake impact. The correlation between aftershocks and slip distribution has frequently been used to estimate the fault dimensions of large historic earthquakes for which no, or insufficient, waveform data is available. With the advent of earthquake inversions that use seismic waveforms and geodetic data to constrain the slip distribution, the study of aftershocks has recently been largely focused on enhancing our understanding of the underlying mechanisms in a broader earthquake mechanics/dynamics framework. However, in a near real-time earthquake monitoring environment, in which aftershocks of large earthquakes are routinely detected and located, these data may also be effective in determining a fast estimate of the mainshock rupture area, which would aid in the rapid assessment of the impact of the earthquake. We have analyzed a considerable number of large recent earthquakes and their aftershock sequences and have developed an effective algorithm that determines the rupture extent of a mainshock from its aftershock distribution, in a fully automatic manner. The algorithm automatically removes outliers by spatial binning, and subsequently determines the best fitting “strike” of the rupture and its length by projecting the aftershock epicenters onto a set of lines that cross the mainshock epicenter with incremental azimuths. For strike-slip or large dip-slip events, for which the surface projection of the rupture is recti-linear, the calculated strike correlates well with the strike of the fault and the corresponding length, determined from the distribution of aftershocks projected onto the line, agrees well with the rupture length. In the case of a smaller dip-slip rupture with an aspect ratio closer to 1, the procedure gives a measure of the rupture extent and dimensions, but not necessarily the strike. We found that using standard earthquake catalogs, such as the National Earthquake Information Center catalog, we can constrain the rupture extent, rupture direction, and in many cases the type of faulting, of the mainshock with the aftershocks that occur within the first hour after the mainshock. However, this data may not be currently available in near real-time. Since our results show that these early aftershock locations may be used to estimate first order rupture parameters for large global earthquakes, the near real-time availability of these data would be useful for fast earthquake damage assessment.

Active faults system and related potential seismic events near Ulaanbaatar, capital of Mongolia.

NASA Astrophysics Data System (ADS)

Schlupp, Antoine; Ferry, Matthieu; Munkhuu, Ulziibat; Sodnomsambuu, Demberel; Al-Ashkar, Abeer

2013-04-01

The region of Ulaanbaatar lies several hundred kilometers from large known active faults that produced magnitude 6 to 8+ earthquakes during the last century. Beside the Hustai fault, which displays a clear morphological expression, no active fault was previously described less than 100 km from the city. In addition, no large historical (i.e. more recent than the 16th c.) earthquakes are known in this region. However, since 2005 a very dense seismic activity has developed over the Emeelt Township area, a mere 10 km from Ulaanbaatar. The activity is characterized by numerous low magnitude events (M<2.8), which are distributed linearly along several tens of kilometers where no active fault has been identified. This raises several questions: Is this seismicity associated to a -yet- unknown active fault? If so, are there other unknown active faults near Ulaanbaatar? Hence, we deployed a multi-disciplinary approach including morpho-tectonic, near-surface geophysical and paleoseismological investigations. We describe four large active faults west and south of Ulaanbaatar, three of them are newly discovered (Emeelt, Sharai, Avdar), one was previously known (Hustai) but without precise study on its seismic potential. The Emeelt seismicity can be mapped over 35 km along N150 and corresponds in the field to a smoothed, but clear, active fault morphology that can be mapped along a 10-km-long section. The fault dips at ~30° NE (GPR and surface morphology observations) and uplifts the eastern block. The age of the last surface rupture observed in trenches is about 10 ka (preliminary OSL dating). Considering a rupture length of 35 km, a full segment rupture would be comparable to the 1967 Mogod earthquake with a magnitude as large as Mw 7. It has to be considered today as a possible scenario for the seismic risk of Ulaanbaatar. The 90-km-long Hustai Range Fault System, oriented WSW-ENE and located about 10 km west of Ulaanbaatar, displays continuous microseismicity with five light to moderate (M 4 - 5.4) earthquakes over the last 40 years. The last surface-rupturing earthquake occurred about 1000 years ago (OSL dating). Alluvial fans affected by the fault suggest the rate of deformation (left lateral with normal component) along the main segment ranges from 0.3 to 0.4 mm/year for the last 120 000 years. Hence, the average recurrence interval for a full-segment M 7-7.5 is likely in the order of 10 ky. However, if the Hustai fault also releases strain during partial ruptures along its strongly segmented trace, a Mw 6.5 event may be expected anytime. However, only the main central fault segment has been investigated in terms of paleoseismicity. The Sharai and Avdar faults, oriented NNE-SSW, were mapped along ~50-km-long sections. Each of these faults was the site of earthquakes of magnitude 6 and more in the past as suggested by morphology and trench observations. Full-segment-ruptures could produce events as large as M 7.2. The precise relationship and interactions between these faults as well as associated earthquakes have to be clarified by collecting more data. They are the key of the seismic hazard and risk of Ulaanbaatar.

Discrimination of tsunamigenic earthquakes by ionospheric sounding using GNSS observations of total electron content from the Sumatran GPS Array

NASA Astrophysics Data System (ADS)

Manta, F.; Feng, L.; Occhipinti, G.; Taisne, B.; Hill, E.

2017-12-01

Tsunami earthquakes generate tsunamis larger than expected for their seismic magnitude. They rupture the shallow megathrust, which is usually at significant distance from land-based monitoring networks. This distance presents a challenge in accurately estimating the magnitude and source extent of tsunami earthquakes. Whether these parameters can be estimated reliably is critical to the success of tsunami early warning systems. In this work, we investigate the potential role of using GNSS-observed ionospheric total electron content (TEC) to discriminate tsunami earthquakes, by introducing for the first time the TEC Intensity Index (TECII) for rapidly identify tsunamigenic earthquakes. We examine two Mw 7.8 megathrust events along the Sumatran subduction zone with data from the Sumatran GPS Array (SuGAr). Both events triggered a tsunami alert that was canceled later. The Banyaks event (April 6th, 2010) did not generate a tsunami and caused only minor earthquake-related damage to infrastructure. On the contrary, the Mentawai event (October 25th, 2010) produced a large tsunami with run-up heights of >16 m along the southwestern coasts of the Pagai Islands. The tsunami claimed more than 400 lives. The primary difference between the two events was the depth of rupture: the Mentawai event ruptured a very shallow (<6 km) portion of the Sunda megathrust, while the Banyaks event ruptured a deeper portion (20-30 km). While we identify only a minor ionospheric signature of the Banyaks event (TECII = 1.05), we identify a strong characteristic acoustic-gravity wave only 8 minutes after the Mentawai earthquake (TECII = 1.14) and a characteristic signature of a tsunami 40 minutes after the event. These two signals reveal the large surface displacement at the rupture, and the consequent destructive tsunami. This comparative study of two earthquakes with the same magnitude at different depths highlights the potential role of ionospheric monitoring by GNSS to tsunami early warning systems

Rupture Dynamics and Ground Motion from Earthquakes in Heterogeneous Media

NASA Astrophysics Data System (ADS)

Bydlon, S.; Dunham, E. M.; Kozdon, J. E.

2012-12-01

Heterogeneities in the material properties of Earth's crust scatter propagating seismic waves. The effects of scattered waves are reflected in the seismic coda and depend on the relative strength of the heterogeneities, spatial arrangement, and distance from source to receiver. In the vicinity of the fault, scattered waves influence the rupture process by introducing fluctuations in the stresses driving propagating ruptures. Further variability in the rupture process is introduced by naturally occurring geometric complexity of fault surfaces, and the stress changes that accompany slip on rough surfaces. We have begun a modeling effort to better understand the origin of complexity in the earthquake source process, and to quantify the relative importance of source complexity and scattering along the propagation path in causing incoherence of high frequency ground motion. To do this we extended our two-dimensional high order finite difference rupture dynamics code to accommodate material heterogeneities. We generate synthetic heterogeneous media using Von Karman correlation functions and their associated power spectral density functions. We then nucleate ruptures on either flat or rough faults, which obey strongly rate-weakening friction laws. Preliminary results for flat faults with uniform frictional properties and initial stresses indicate that off-fault material heterogeneity alone can lead to a complex rupture process. Our simulations reveal the excitation of high frequency bursts of waves, which radiate energy away from the propagating rupture. The average rupture velocity is thus reduced relative to its value in simulations employing homogeneous material properties. In the coming months, we aim to more fully explore parameter space by varying the correlation length, Hurst exponent, and amplitude of medium heterogeneities, as well as the statistical properties characterizing fault roughness.

Long-Wavelength Rupturing Instability in Surface-Tension-Driven Benard Convection

NASA Technical Reports Server (NTRS)

Swift, J. B.; Hook, Stephen J. Van; Becerril, Ricardo; McCormick, W. D.; Swinney, H. L.; Schatz, Michael F.

1999-01-01

A liquid layer with a free upper surface and heated from below is subject to thermocapillary-induced convective instabilities. We use very thin liquid layers (0.01 cm) to significantly reduce buoyancy effects and simulate Marangoni convection in microgravity. We observe thermocapillary-driven convection in two qualitatively different modes, short-wavelength Benard hexagonal convection cells and a long-wavelength interfacial rupturing mode. We focus on the long-wavelength mode and present experimental observations and theoretical analyses of the long-wavelength instability. Depending on the depths and thermal conductivities of the liquid and the gas above it, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. Linear stability theory gives good agreement to the experimental measurements of onset as long as sidewall effects are taken into account. Nonlinear theory correctly predicts the subcritical nature of the bifurcation and the selection between the dry spot and high spots.

Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.

PubMed

Tsai, Ya-Yi; I, Lin

2014-07-01

Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.

Scaling law on formation and rupture of a dynamical liquid bridge

NASA Astrophysics Data System (ADS)

Zhang, Huang; Zhang, Zehao; Liu, Qianfeng; Li, Shuiqing; Department of Thermal Engineering, Tsinghua University Collaboration; Institute of Nuclear Energy; Technology, Tsinghua University Collaboration

2017-11-01

The formation and breakup of a pendular liquid bridge in dynamic state is investigated experimentally. The experimental setup arises from a system to measure the coefficient of restitution (COR) of a glass sphere impacting and bouncing on a wetted surface. We compare the effect of surface tension and gravity on the liquid bridge rupture by the capillary length κ-1. For water and liquid 1 (50% water mixed with 50% glycerol), the gravity is dominant on the liquid bridge breakup. And we find that the rupture distance is in good linear trend with the non-dimensional number G by the scaling law analysis. Further, for liquid 2 (25% water mixed with 75% glycerol) that is relatively high viscous, the linear changing of the rupture distance with the capillary number Ca is found. The relation of the rupture distance with G and Ca would be helpful in understanding the complex behavior of the dynamical liquid bridge. This work was funded by the Major State Basic Research Development Program of China (Grant No. 2016YFC0203705) and the China Postdoctoral Science Foundation (Grant No. 2016M601024).

Spontaneous splenic rupture in an active duty Marine upon return from Iraq: a case report

PubMed Central

2010-01-01

Introduction Atraumatic splenic rupture is a rare event that has been associated with several infectious disease processes. In the active duty military population, potential exposure to these pathogens is significant. Here we discuss the case of an active duty Marine with spontaneous splenic rupture upon return from a six-month deployment in Iraq. Case presentation A previously healthy 30-year-old Caucasian male active duty Marine presented with abdominal pain, fever and diarrhea after deployment to Iraq in support of Operation Iraqi Freedom. Based on clinical and radiographic evidence, a diagnosis of spontaneous splenic rupture was ultimately suspected. After exploratory laparotomy with confirmation of rupture, splenectomy was performed, and the patient made a full, uneventful recovery. Histopathologic examination revealed mild splenomegaly with a ruptured capsule of undetermined cause. Conclusion Spontaneous splenic rupture is a rare event that may lead to life-threatening hemorrhage if not diagnosed and treated quickly. Although the cause of this patient's case was unknown, atraumatic splenic rupture has been associated with a variety of infectious diseases and demonstrates some risks the active duty military population may face while on deployment. Having an awareness of these pathogens and their role in splenic rupture, clinicians caring for military personnel must be prepared to recognize and treat this potentially fatal complication. PMID:21054871

Evidence for two surface ruptures in the past 500 years on the San Andreas fault at Frazier Mountain, California

USGS Publications Warehouse

Lindvall, S.C.; Rockwell, T.K.; Dawson, T.E.; Helms, J.G.; Bowman, K.W.

2002-01-01

We conducted paleoseismic studies in a closed depression along the San Andreas fault on the north flank of Frazier Mountain near Frazier Park, California. We recognized two earthquake ruptures in our trench exposure and interpreted the most recent rupture, event 1, to represent the historical 1857 earthquake. We also exposed evidence of an earlier surface rupture, event 2, along an older group of faults that did not rerupture during event 1. Radiocarbon dating of the stratigraphy above and below the earlier event constrains its probable age to between A.D. 1460 and 1600. Because we documented continuous, unfaulted stratigraphy between the earlier event horizon and the youngest event horizon in the portion of the fault zone exposed, we infer event 2 to be the penultimate event. We observed no direct evidence of an 1812 earthquake in our exposures. However, we cannot preclude the presence of this event at our site due to limited age control in the upper part of the section and the possibility of other fault strands beyond the limits of our exposures. Based on overlapping age ranges, event 2 at Frazier Mountain may correlate with event B at the Bidart fan site in the Carrizo Plain to the northwest and events V and W4 at Pallett Creek and Wrightwood, respectively, to the southeast. If the events recognized at these multiple sites resulted from the same surface rupture, then it appears that the San Andreas fault has repeatedly failed in large ruptures similar in extent to 1857.

Structure, Frictional Melting and Fault Weakening during the 2008 Mw 7.9 Wenchuan Earthquake Slip: Observation from the WFSD Drilling Core Samples

NASA Astrophysics Data System (ADS)

Li, H.; Wang, H.; Li, C.; Zhang, J.; Sun, Z.; Si, J.; Liu, D.; Chevalier, M. L.; Han, L.; Yun, K.; Zheng, Y.

2015-12-01

The 2008 Mw7.9 Wenchuan earthquake produced two co-seismic surface ruptures along Yingxiu-Beichuan fault (~270 km) and the Guanxian-Anxian fault (~80 km) simultaneously in the Longmen Shan thrust belt. Besides, two surface rupture zones were tracked in the southern segment of the Yingxiu-Beichuan rupture zone, one along the Yingxiu fault, the other along the Shenxigou-Longchi fault, which both converged into one rupture zone at the Bajiaomiao village, Hongkou town, where one distinct fault plane with two striation orientations was exposed. The Wenchuan earthquake Fault Scientific Drilling project (WFSD) was carried out right after the earthquake to investigate its faulting mechanisms and rupture process. Six boreholes were drilled along the rupture zones with depths ranging from 600 to 2400 m. WFSD-1 and WFSD-2 are located at the Bajiaomiao area, the southern segment of the Yingxiu-Beichuan rupture zone, while WFSD-4 and WFSD-4S are in the Nanba town area, in the northern part of the rupture zone. Detailed research showed that ~1 mm thick Principal Slip Zone (PSZ) of the Wenchuan earthquake is located at ~589 m-depth in the WFSD-1 cores. Graphite present in the PSZ indicates a low fault strength. Long-term temperature monitoring shows an extremely low fault friction coefficient during the earthquake. Recently, another possible PSZ was found in WFSD-1 cores at ~732 m-depth, with a ~2 mm thick melt layer in the fault gouge, where feldspar was melted but quartz was not, indicating that the frictional melting temperature was 1230°C < T < 1720°C. These two PSZs at depth may correspond to the two co-seismic surface rupture zones. Besides, the Wenchuan earthquake PSZ was also recognized in the WFSD-4S cores, at ~1084 m-depth. About 200-400 μm thick melt layer (fault vein, mainly feldspar), as well as melt injection veins, were observed in the slip zone, where oblique distinct striations were visible on the slip surface. Therefore, there are two PSZs in the shallow crust at the southern segment along the Yingxiu-Beichuan fault, and another one along the northern segment. Melt and graphite in the PSZs indicate that the frictional melting and thermal pressurization are the main fault mechanisms during the Wenchuan earthquake. The melt and graphite can be considered as markers of large earthquakes.

Comparing the effects of mechanical perturbation training with a compliant surface and manual perturbation training on joints kinematics after ACL-rupture.

PubMed

Nawasreh, Zakariya; Failla, Mathew; Marmon, Adam; Logerstedt, David; Snyder-Mackler, Lynn

2018-05-23

Performing physical activities on a compliant surface alters joint kinematics and increases joints stiffness. However, the effect of compliant surface on joint kinematics after ACL-rupture is yet unknown. To compare the effects of mechanical perturbation training with a compliant surface to manual perturbation training on joint kinematics after ACL-rupture. Sixteen level I/II athletes with ACL-rupture participated in this preliminary study. Eight patients received mechanical perturbation with compliant surface (Mechanical) and 8 patients received manual perturbation training (Manual). Patients completed standard gait analysis before (Pre) and after (Post) training. Significant group-by-time interactions were found for knee flexion angle at initial contact (IC) and peak knee flexion (PKF) (p<0.004), with manual group significantly increased knee flexion angle at IC and PKF (p<0.03). Main effects of group were found for hip flexion angle at IC (Manual:34.34+3.51°, Mechanical:27.68+4.08°, p = 0.011), hip rotation angle at PKE (Manual:-3.40+4.78°, Mechanical:5.43+4.78°, p < 0.0001), and knee adduction angle at PKE (Manual:-2.00+2.23°, Mechanical:0.55+2.23°, p = 0.039). Main effects of time were found for hip adduction angle at PKE (Pre:6.98+4.48°, Post:8.41+4.91°, p = 0.04), knee adduction angle at IC (Pre:-2.90+3.50°, Post:-0.62+2.58°, p = 0.03), ankle adduction angle at IC (Pre:2.16+3.54, Post:3.8+3.68, p = 0.008), and ankle flexion angle at PKF (Pre:-4.55+2.77°, Post:-2.39+3.48°, p = 0.01). Training on a compliant surface induces different effects on joint kinematics compared to manual perturbation training after ACL-rupture. Manual perturbation improved hip alignment and increased knee flexion angles, while mechanical training decreased knee flexion angles throughout the stance phase. Administering training on a compliant surface after ACL-rupture may help improving dynamic knee stability, however, long-term effects on knee health needs to be determined. Copyright © 2018 Elsevier B.V. All rights reserved.

Long-wavelength Instability in Surface-tension-driven Bénard Convection

NASA Astrophysics Data System (ADS)

van Hook, Stephen J.

1997-03-01

Laboratory experiments and numerical simulations reveal that a liquid layer heated from below and possessing a free upper surface can undergo a long-wavelength deformational instability that causes rupture of the interface.(S. J. VanHook, M. F. Schatz, W. D. McCormick, J. B. Swift, and H. L. Swinney, Phys. Rev. Lett.) 75, 4397 (1995). Depending on the depth and thermal conductivity of the liquid and the overlying gas layer, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. This long-wavelength instability competes with the formation of Bénard hexagons for thin or viscous liquid layers, or for liquid layers in microgravity.

Infrasonic Observations of Ground Shaking along the 2010 Mw 7.2 El Mayor Rupture

NASA Astrophysics Data System (ADS)

Degroot-Hedlin, C. D.; Walker, K.

2010-12-01

The Mw 7.2 El Mayor earthquake in northeast Baja California generated seismic waves that were felt for up to 90 seconds throughout southern California and northern Baja. The locations of the epicenter, aftershocks, and surface rupture suggest that the rupture was not focused at one specific location, but initiated near El Mayor, Mexico and extended northwest for roughly 120 km through the U.S. border. We analyze infrasound and seismic data recorded by three arrays and show that the surface shaking in the vicinity of the rupture also generated infrasound that was detected at least 200 km away to the north and west of the epicentral region, despite stratospheric winds from the west that only favor eastward propagation. Frequency domain beamforming of infrasound array signals recorded by an array near San Diego (MRIAR) shows a time progression of signal back azimuth that spans the entire rupture length. Ray trace modeling using 4-D atmospheric velocity models suggests that the observed infrasound signals refracted in the thermosphere. The signals have frequencies from 1 to 12 Hz, which is rather high given the level of thermospheric attenuation predicted by traditional models. A secondary infrasound wavetrain that arrived at MRIAR before the epicentral infrasound appears to have originated from an infrasonic radiator south of the array that was excited by the passing surface waves.

The 2016-2017 central Italy coseismic surface ruptures and their meaning with respect to foreseen active fault systems segmentation

NASA Astrophysics Data System (ADS)

De Martini, P. M.; Pucci, S.; Villani, F.; Civico, R.; Del Rio, L.; Cinti, F. R.; Pantosti, D.

2017-12-01

In 2016-2017 a series of moderate to large normal faulting earthquakes struck central Italy producing severe damage in many towns including Amatrice, Norcia and Visso and resulting in 299 casualties and >20,000 homeless. The complex seismic sequence depicts a multiple activation of the Mt. Vettore-Mt. Bove (VBFS) and the Laga Mts. fault systems, which were considered in literature as independent segments characterizing a recent seismic gap in the region comprised between two modern seismic sequences: the 1997-1998 Colfiorito and the 2009 L'Aquila. We mapped in detail the coseismic surface ruptures following three mainshocks (Mw 6.0 on 24th August, Mw 5.9 and Mw 6.5 on 26th and 30th October, 2016, respectively). Primary surface ruptures were observed and recorded for a total length of 5.2 km, ≅10 km and ≅25 km, respectively, along closely-spaced, parallel or subparallel, overlapping or step-like synthetic and antithetic fault splays of the activated fault systems, in some cases rupturing repeatedly the same location. Some coseismic ruptures were mapped also along the Norcia Fault System, paralleling the VBFS about 10 km westward. We recorded geometric and kinematic characteristics of the normal faulting ruptures with an unprecedented detail thanks to almost 11,000 oblique photographs taken from helicopter flights soon after the mainshocks, verified and integrated with field data (more than 7000 measurements). We analyze the along-strike coseismic slip and slip vectors distribution to be observed in the context of the geomorphic expression of the disrupted slopes and their depositional and erosive processes. Moreover, we constructed 1:10.000 scale geologic cross-sections based on updated maps, and we reconstructed the net offset distribution of the activated fault system to be compared with the morphologic throws and to test a cause-effect relationship between faulting and first-order landforms. We provide a reconstruction of the 2016 coseismic rupture pattern as representative of the VBFS behavior, a discussion on the fault system boundaries persistence, and on the significance of the repeated surface faulting at same location.

On the Prediction of Ground Motion

NASA Astrophysics Data System (ADS)

Lavallee, D.; Schmedes, J.; Archuleta, R. J.

2012-12-01

Using a slip-weakening dynamic model of rupture, we generated earthquake scenarios that provided the spatio-temporal evolution of the slip on the fault and the radiated field at the free surface. We observed scenarios where the rupture propagates at a supershear speed on some parts of the fault while remaining subshear for other parts of the fault. For some scenarios with nearly identical initial conditions, the rupture speed was always subshear. For both types of scenarios (mixture of supershear and subshear speeds and only subshear), we compute the peak ground accelerations (PGA) regularly distributed over the Earth's surface. We then calculate the probability density functions (PDF) of the PGA. For both types of scenarios, the PDF curves are asymmetrically shaped and asymptotically attenuated according to power law. This behavior of the PDF is similar to that observed for the PDF curves of PGA recorded during earthquakes. The main difference between scenarios with a supershear rupture speed and scenarios with only subshear rupture speed is the range of PGA values. Based on these results, we investigate three issues fundamental for the prediction of ground motion. It is important to recognize that recorded ground motions during an earthquake sample a small fraction of the radiation field. It is not obvious that such sampling will capture the largest ground motion generated during an earthquake, nor that the number of stations is large enough to properly infer the statistical properties associated with the radiation field. To quantify the effect of under (or low) sampling of the radiation field, we design three experiments. For a scenario where the rupture speed is only subshear, we construct multiple sets of observations. Each set is comprised of 100 randomly selected PGA values from all of the PGA's calculated at the Earth's surface. In the first experiment, we evaluate how the distributions of PGA in the sets compare with the distribution of all the PGA. For this experiment, we used different statistical tests (e.g. chi-square). This experiment quantifies the likelihood that a random set of PGA can be used to infer the statistical properties of all the PGA. In the second experiment, we fit the PDF of the PGA of every set with probability laws used in the literature to describe the PDF of recorded PGA: the lognormal law, the generalized maximum extreme value law, and the Levy law. For each set, the probability laws are then used to compute the probability to observe a PGA value that will cause "moderate to heavy" potential damage according to Instrumental Intensity scale developed by USGS. For each probability law, we compare predictions based on the set with the prediction estimated from all the PGA. This experiment quantifies the reliability and uncertainty in predicting an outcome due to under sampling the radiation field. The third experiment consists in using the sets discussed above and repeats the two investigations discussed above but this time comparing with a scenario where the rupture has a supershear speed over part of the fault. The objective here is to assess additional uncertainty in predicting PGA and damage resulting from ruptures that have supershear speeds.

Hemorrhagic Shock as a Sequela of Splenic Rupture in a Patient with Infectious Mononucleosis: Focus on the Potential Role of Salicylates

PubMed Central

Bouliaris, Konstantinos; Karangelis, Dimos; Daskalopoulos, Marios; Spanos, Konstantinos; Fanariotis, Michael; Giaglaras, Anargyros

2012-01-01

Despite the fact that the vast majority of splenic ruptures are traumatic, infectious mononucleosis has been incriminated as a major predisposing factor that affects the integrity of the spleen, thus causing atraumatic ruptures and life-threatening hemorrhages. Herein we present a case of a 23-year-old Caucasian male who underwent an emergency laparotomy for acute abdomen and hemorrhagic shock, caused by spontaneous splenic rupture secondary to infectious mononucleosis. The potential role of salicylates in the development of a hemorrhagic complication in a patient with infectious mononucleosis is discussed. PMID:22431933

Quantifying near-field and off-fault deformation patterns of the 1992 Mw 7.3 Landers earthquake

NASA Astrophysics Data System (ADS)

Milliner, Christopher W. D.; Dolan, James F.; Hollingsworth, James; Leprince, Sebastien; Ayoub, Francois; Sammis, Charles G.

2015-05-01

Coseismic surface deformation in large earthquakes is typically measured using field mapping and with a range of geodetic methods (e.g., InSAR, lidar differencing, and GPS). Current methods, however, either fail to capture patterns of near-field coseismic surface deformation or lack preevent data. Consequently, the characteristics of off-fault deformation and the parameters that control it remain poorly understood. We develop a standardized method to fully measure the surface, near-field, coseismic deformation patterns at high resolution using the COSI-Corr program by correlating pairs of aerial photographs taken before and after the 1992 Mw 7.3 Landers earthquake. COSI-Corr offers the advantage of measuring displacement across the entire zone of surface deformation and over a wider aperture than that available to field geologists. For the Landers earthquake, our measured displacements are systematically larger than the field measurements, indicating the presence of off-fault deformation. We show that 46% of the total surface displacement occurred as off-fault deformation, over a mean deformation width of 154 m. The magnitude and width of off-fault deformation along the rupture is primarily controlled by the macroscopic structural complexity of the fault system, with a weak correlation with the type of near-surface materials through which the rupture propagated. Both the magnitude and width of distributed deformation are largest in stepovers, bends, and at the southern termination of the surface rupture. We find that slip along the surface rupture exhibits a consistent degree of variability at all observable length scales and that the slip distribution is self-affine fractal with dimension of 1.56.

High-resolution seismic profiling reveals faulting associated with the 1934 Ms 6.6 Hansel Valley earthquake (Utah, USA)

USGS Publications Warehouse

Bruno, Pier Paolo G.; Duross, Christopher; Kokkalas, Sotirios

2017-01-01

The 1934 Ms 6.6 Hansel Valley, Utah, earthquake produced an 8-km-long by 3-km-wide zone of north-south−trending surface deformation in an extensional basin within the easternmost Basin and Range Province. Less than 0.5 m of purely vertical displacement was measured at the surface, although seismologic data suggest mostly strike-slip faulting at depth. Characterization of the origin and kinematics of faulting in the Hansel Valley earthquake is important to understand how complex fault ruptures accommodate regions of continental extension and transtension. Here, we address three questions: (1) How does the 1934 surface rupture compare with faults in the subsurface? (2) Are the 1934 fault scarps tectonic or secondary features? (3) Did the 1934 earthquake have components of both strike-slip and dip-slip motion? To address these questions, we acquired a 6.6-km-long, high-resolution seismic profile across Hansel Valley, including the 1934 ruptures. We observed numerous east- and west-dipping normal faults that dip 40°−70° and offset late Quaternary strata from within a few tens of meters of the surface down to a depth of ∼1 km. Spatial correspondence between the 1934 surface ruptures and subsurface faults suggests that ruptures associated with the earthquake are of tectonic origin. Our data clearly show complex basin faulting that is most consistent with transtensional tectonics. Although the kinematics of the 1934 earthquake remain underconstrained, we interpret the disagreement between surface (normal) and subsurface (strike-slip) kinematics as due to slip partitioning during fault propagation and to the effect of preexisting structural complexities. We infer that the 1934 earthquake occurred along an ∼3-km wide, off-fault damage zone characterized by distributed deformation along small-displacement faults that may be alternatively activated during different earthquake episodes.

Faulting, damage, and intensity in the Canyondam earthquake of May 23, 2013

USGS Publications Warehouse

Chapman, K.; Gold, M.B.; Boatwright, John; Sipe, J.; Quitoriano, V.; Dreger, D.; Hardebeck, Jeanne

2016-09-23

On Thursday evening, May 23, 2013 (0347 May 24 UTC), a moment magnitude (Mw) = 5.7 earthquake occurred northeast of Canyondam, California. A two-person team of U.S. Geological Survey scientists went to the area to search for surface rupture and to canvass damage in the communities around Lake Almanor. While the causative fault had not been identified at the time of the field survey, surface rupture was expected to have occurred just south of Lake Almanor, approximately 2–4 kilometers south of the epicenter. No surface rupture was discovered. Felt intensity among the communities around Lake Almanor appeared to vary significantly. Lake Almanor West (LAW), Lake Almanor Country Club (LACC), and Hamilton Branch (HB) experienced Modified Mercalli Intensity (MMI) ≥7, whereas other communities around the lake experienced MMI ≤6; the maximum observed intensity was MMI 8, in LAW. Damage in the high intensity areas consisted of broken and collapsed chimneys, ruptured pipes, and some damage to foundations and to structural elements within houses. Although this shaking damage is not usually expected for an Mw 5.7 earthquake, the intensities at Lake Almanor Country Club correlate with the peak ground acceleration (38 percent g) and peak ground velocity (30 centimeters per second) recorded by the California Strong Motion Instrumentation Program accelerometer located at the nearby Lake Almanor Fire Station. The intensity distribution for the three hardest hit areas (LAW, LACC, and HB) appears to increase as the azimuth from epicenter to the intensity sites approaches the fault strike. The small communities of Almanor and Prattville on the southwestern shore of Lake Almanor experienced somewhat lower intensities. The town of Canyondam experienced a lower intensity as well, despite its location up-dip of the earthquake rupture. This report contains information on the earthquake itself, the search for surface rupture, and the damage we observed and compiled from other sources. 

The history of late holocene surface-faulting earthquakes on the central segments of the Wasatch fault zone, Utah

USGS Publications Warehouse

Duross, Christopher; Personius, Stephen; Olig, Susan S; Crone, Anthony J.; Hylland, Michael D.; Lund, William R; Schwartz, David P.

2017-01-01

The Wasatch fault (WFZ)—Utah’s longest and most active normal fault—forms a prominent eastern boundary to the Basin and Range Province in northern Utah. To provide paleoseismic data for a Wasatch Front regional earthquake forecast, we synthesized paleoseismic data to define the timing and displacements of late Holocene surface-faulting earthquakes on the central five segments of the WFZ. Our analysis yields revised histories of large (M ~7) surface-faulting earthquakes on the segments, as well as estimates of earthquake recurrence and vertical slip rate. We constrain the timing of four to six earthquakes on each of the central segments, which together yields a history of at least 24 surface-faulting earthquakes since ~6 ka. Using earthquake data for each segment, inter-event recurrence intervals range from about 0.6 to 2.5 kyr, and have a mean of 1.2 kyr. Mean recurrence, based on closed seismic intervals, is ~1.1–1.3 kyr per segment, and when combined with mean vertical displacements per segment of 1.7–2.6 m, yield mean vertical slip rates of 1.3–2.0 mm/yr per segment. These data refine the late Holocene behavior of the central WFZ; however, a significant source of uncertainty is whether structural complexities that define the segments of the WFZ act as hard barriers to ruptures propagating along the fault. Thus, we evaluate fault rupture models including both single-segment and multi-segment ruptures, and define 3–17-km-wide spatial uncertainties in the segment boundaries. These alternative rupture models and segment-boundary zones honor the WFZ paleoseismic data, take into account the spatial and temporal limitations of paleoseismic data, and allow for complex ruptures such as partial-segment and spillover ruptures. Our data and analyses improve our understanding of the complexities in normal-faulting earthquake behavior and provide geological inputs for regional earthquake-probability and seismic hazard assessments.

Geologic and paleoseismic study of the Lavic Lake fault at Lavic Lake Playa, Mojave Desert, Southern California

USGS Publications Warehouse

Rymer, M.J.; Seitz, G.G.; Weaver, K.D.; Orgil, A.; Faneros, G.; Hamilton, J.C.; Goetz, C.

2002-01-01

Paleoseismic investigations of the Lavic Lake fault at Lavic Lake playa place constraints on the timing of a possible earlier earthquake along the 1999 Hector Mine rupture trace and reveal evidence of the timing of the penultimate earthquake on a strand of the Lavic Lake fault that did not rupture in 1999. Three of our four trenches, trenches A, B, and C, were excavated across the 1999 Hector Mine rupture; a fourth trench, D, was excavated across a vegetation lineament that had only minor slip at its southern end in 1999. Trenches A-C exposed strata that are broken only by the 1999 rupture; trench D exposed horizontal bedding that is locally warped and offset by faults. Stratigraphic evidence for the timing of an earlier earthquake along the 1999 rupture across Lavic Lake playa was not exposed. Thus, an earlier event, if there was one along that rupture trace, predates the lowest stratigraphic level exposed in our trenches. Radiocarbon dating of strata near the bottom of trenches constrains a possible earlier event to some time earlier than about 4950 B.C. Buried faults revealed in trench D are below a vegetation lineament at the ground surface. A depositional contact about 80 cm below the ground surface acts as the upward termination of fault breaks in trench D. Thus, this contact may be the event horizon for a surface-rupturing earthquake prior to 1999-the penultimate earthquake on the Lavic Lake fault. Radiocarbon ages of detrital charcoal samples from immediately below the event horizon indicate that the earthquake associated with the faulting occurred later than A.D. 260. An approximately 1300-year age difference between two samples at about the same stratigraphic level below the event horizon suggests the potential for a long residence time of detrital charcoal in the area. Coupled with a lack of bioturbation that could introduce young organic material into the stratigraphic section, the charcoal ages provide only a maximum bounding age; thus, the recognized event may be younger. There is abundant, subtle evidence for pre-1999 activity of the Lavic Lake fault in the playa area, even though the fault was not mapped near the playa prior to the Hector Mine earthquake. The most notable indicators for long-term presence of the fault are pronounced, persistent vegetation lineaments and uplifted basalt exposures. Primary and secondary slip occurred in 1999 on two southern vegetation lineaments, and minor slip locally formed on a northern lineament; trench exposures across the northern vegetation lineament revealed the post-A.D. 260 earthquake, and a geomorphic trough extends northward into alluvial fan deposits in line with this lineament. The presence of two basalt exposures in Lavic lake playa indicates the presence of persistent compressional steps and uplift along the fault. Fault-line scarps are additional geomorphic markers of repeated slip events in basalt exposures.

Coseismic Contortion and Coupled Nocturnal Ionospheric Perturbations During 2016 Kaikoura, Mw 7.8 New Zealand Earthquake

NASA Astrophysics Data System (ADS)

Bagiya, Mala S.; Sunil, P. S.; Sunil, A. S.; Ramesh, D. S.

2018-02-01

The oblique-thrust Kaikoura earthquake of Mw 7.8 that struck New Zealand on 13 November 2016 at 11:02:56 UTC (local time at 00:02:56 a.m. on 14 November 2016) was one of the most geometrically and tectonically complex earthquakes recorded onshore in modern seismology. The event ruptured in the region of multisegmented faults and propagated unilaterally northeastward for more than 170 km from the epicenter. The GPS derived coseismic surface displacements reveal a larger widespread horizontal and vertical coseismic surface offsets of 6 m and 2 m, respectively, with two distinct tectonic thrust zones. We study the characteristics of coseismic ionospheric perturbations based on tectonic and nontectonic forcing mechanisms and demonstrate that these perturbations are linked to two distinct surface thrust zones with rotating horizontal reinforcement trending the rupture, rather than merely to the displacements oriented along the rupture propagation direction.

Is internal friction friction?

USGS Publications Warehouse

Savage, J.C.; Byerlee, J.D.; Lockner, D.A.

1996-01-01

Mogi [1974] proposed a simple model of the incipient rupture surface to explain the Coulomb failure criterion. We show here that this model can plausibly be extended to explain the Mohr failure criterion. In Mogi's model the incipient rupture surface immediately before fracture consists of areas across which material integrity is maintained (intact areas) and areas across which it is not (cracks). The strength of the incipient rupture surface is made up of the inherent strength of the intact areas plus the frictional resistance to sliding offered by the cracked areas. Although the coefficient of internal friction (slope of the strength versus normal stress curve) depends upon both the frictional and inherent strengths, the phenomenon of internal friction can be identified with the frictional part. The curvature of the Mohr failure envelope is interpreted as a consequence of differences in damage (cracking) accumulated in prefailure loading at different confining pressures.

Surface faulting along the inland Itozawa normal fault (eastern Japan) and relation to the 2011 Tohoku-oki megathrust earthquake

NASA Astrophysics Data System (ADS)

Ferry, Matthieu; Tsutsumi, Hiroyuki; Meghraoui, Mustapha; Toda, Shinji

2013-04-01

The 11 March 2011 Mw 9 Tohoku-oki earthquake ruptured ~500 km length of the Japan Trench along the coast of eastern Japan and significantly impacted the stress regime within the crust. The resulting change in seismicity over the Japan mainland was exhibited by the 11 April 2011 Mw 6.6 Iwaki earthquake that ruptured the Itozawa and Yunodake faults. Trending NNW and NW, respectively, these 70-80° W-dipping faults bound the Iwaki basin of Neogene age and have been reactivated simultaneously both along 15-km-long sections. Here, we present initial results from a paleoseismic excavation performed across the Itozawa fault within the Tsunagi Valley at the northern third of the observed surface rupture. At the Tsunagi site, the rupture affects a rice paddy, which provides an ideally horizontal initial state to collect detailed and accurate measurements. The surface break is composed of a continuous 30-to-40-cm-wide purely extensional crack that separates the uplifted block from a gently dipping 1-to-2-m-wide strip affected by right-stepping en-echelon cracks and locally bounded by a ~0.1-m-high reverse scarplet. Total station across-fault topographic profiles indicate the pre-earthquake ground surface was vertically deformed by ~0.6 m while direct field examinations reveal that well-defined rice paddy limits have been left-laterally offset by ~0.1 m. The 12-m-long, 3.5-m-deep trench exposes the 30-to-40-cm-thick cultivated soil overlaying a 1-m-thick red to yellow silt unit, a 2-m-thick alluvial gravel unit and a basal 0.1-1-m-thick organic-rich silt unit. Deformation associated to the 2011 rupture illustrates down-dip movement along a near-vertical fault with a well-expressed bending moment at the surface and generalized warping. On the north wall, the intermediate gravel unit displays a deformation pattern similar to granular flow with only minor discrete faulting and no splay to be continuously followed from the main fault to the surface. On the south wall, warping dominates as well but with some strain localization along two major splays that exhibit 15-20 cm of vertical offset. On both walls, the basal silt unit is vertically deformed by ~0.6 m, similarly to what is observed for the 2011 rupture. Furthermore, the base of said silt unit exhibits indication for secondary faulting prior to the 2011 event and that resemble cracks observed at the present-day surface. This suggests that the Itozawa fault has already ruptured in a similar fashion in the late Pleistocene). Hence, recent activity of the Itozawa fault may be controlled entirely by large to giant earthquakes along the Japan Trench.

EMG monitoring during functional non-surgical therapy of Achilles tendon rupture.

PubMed

Hüfner, Tobias; Wohifarth, Kai; Fink, Matthias; Thermann, H; Rollnik, Jens D

2002-07-01

After surgical therapy of Achilles tendon rupture, neuromuscular changes may persist, even one year after surgery. We were interested whether these changes are also evident following a non-surgical functional therapy (Variostabil therapy boot/Adidas). Twenty-one patients with complete Achilles tendon rupture were enrolled in the study (mean age 38.5 years, range 24 to 60; 18 men, three women) and followed-up clinically and with surface EMG of the gastrocnemius muscles after four, eight, 12 weeks, and one year after rupture. EMG differences between the affected and non-affected side could only be observed at baseline and after four weeks following Achilles tendon rupture. The results from our study show that EMG changes are not found following non-surgical functional therapy.

Seismic rupture process of the 2010 Haiti Earthquake (Mw7.0) inferred from seismic and SAR data

NASA Astrophysics Data System (ADS)

Santos, Rúben; Caldeira, Bento; Borges, José; Bezzeghoud, Mourad

2013-04-01

On January 12th 2010 at 21:53, the Port-au-Prince - Haiti region was struck by an Mw7 earthquake, the second most deadly of the history. The last seismic significant events in the region occurred in November 1751 and June 1770 [1]. Geodetic and geological studies, previous to the 2010 earthquake [2] have warned to the potential of the destructive seismic events in that region and this event has confirmed those warnings. Some aspects of the source of this earthquake are nonconsensual. There is no agreement in the mechanism of rupture or correlation with the fault that should have it generated [3]. In order to better understand the complexity of this rupture, we combined several techniques and data of different nature. We used teleseismic body-wave and Synthetic Aperture Radar data (SAR) based on the following methodology: 1) analysis of the rupture process directivity [4] to determine the velocity and direction of rupture; 2) teleseismic body-wave inversion to obtain the spatiotemporal fault slip distribution and a detailed rupture model; 3) near field surface deformation modeling using the calculated seismic rupture model and compared with the measured deformation field using SAR data of sensor Advanced Land Observing Satellite - Phased Array L-band SAR (ALOS-PALSAR). The combined application of seismic and geodetic data reveals a complex rupture that spread during approximately 12s mainly from WNW to ESE with average velocity of 2,5km/s, on a north-dipping fault plane. Two main asperities are obtained: the first (and largest) occurs within the first ~ 5sec and extends for approximately 6km around the hypocenter; the second one, that happens in the remaining 6s, covers a near surface rectangular strip with about 12km long by 3km wide. The first asperity is compatible with a left lateral strike-slip motion with a small reverse component; the mechanism of second asperity is predominantly reverse. The obtained rupture process allows modeling a coseismic deformation which is in agreement with the deformation field measured by InSAR. [1] Bakun W, Flores C, Brink U, 2012 Significant Earthquakes on the Enriquillo Fault System, Hispaniola, 1500-2010: Implications for Seismic Hazard. Bul. Seis. Soc. of America, 102(1):18-30. [2] Dixon, T. et al., 1998. Relative motion between the Caribbean and North American plates and related boundary zone deformation based on a decade of GPS observations. J. Geophys. Res. 103, 15157-15182. [3] Mercier de Lépinay, B., Deschamps, A., Klingelhoefer, F., Mazabraud, Y., Delouis, B., Clouard, V., Hello Y., Crozon, J., Marcaillou, B., Graindorge, D., Vallée M., Perrot, J., Bouin, M., Saurel, J., Charvis, Philippe, C. and St-Louis, 2011. The 2010 Haiti earthquake: A complex fault pattern constrained by seismologic and tectonic observations, Geoph. Res. Let., 30, L22305 [4] Caldeira B, Bezzeghoud M, Borges JF., 2009 DIRDOP: a directivity approach to determining the seismic rupture velocity vector. J. of Seis.. 2009;14(3):565-600.

Slip Model of the 2015 Mw 7.8 Gorkha (Nepal) Earthquake from Inversions of ALOS-2 and GPS Data

NASA Astrophysics Data System (ADS)

Wang, K.; Fialko, Y. A.

2015-12-01

We use surface deformation measurements including Interferometric Synthetic Aperture Radar (InSAR) data acquired by the ALOS-2 mission of the Japanese Aerospace Exploration Agency (JAXA) and Global Positioning System (GPS) data to invert for the fault geometry and coseismic slip distribution of the 2015 Mw 7.8 Gorkha earthquake in Nepal. Assuming that the ruptured fault connects to the surface trace of the of Main Frontal Thrust fault (MFT) between 84.34E and 86.19E, the best-fitting model suggests a dip angle of 7 degrees. The moment calculated from the slip model is 6.17*1020 Nm, corresponding to the moment magnitude of 7.79. The rupture of the 2015 Gorkha earthquake was dominated by thrust motion that was primarily concentrated in a 150-km long zone 50 to 100 km northward from the surface trace of the Main Frontal Thrust (MFT), with maximum slip of ~6 m at a depth of ~ 8 km. Data thus indicate that the 2015 Gorkha earthquake ruptured a deep part of the seismogenic zone, in contrast to the 1934 Bihar-Nepal earthquake, which had ruptured a shallow part of the adjacent fault segment to the East.

Dependence of near field co-seismic ionospheric perturbations on surface deformations: A case study based on the April, 25 2015 Gorkha Nepal earthquake

NASA Astrophysics Data System (ADS)

Sunil, A. S.; Bagiya, Mala S.; Catherine, Joshi; Rolland, Lucie; Sharma, Nitin; Sunil, P. S.; Ramesh, D. S.

2017-03-01

Ionospheric response to the recent 25 April 2015 Gorkha, Nepal earthquake is studied in terms of Global Positioning System-Total Electron Content (GPS-TEC) from the viewpoints of source directivity, rupture propagation and associated surface deformations, over and near the fault plane. The azimuthal directivity of co-seismic ionospheric perturbations (CIP) amplitudes from near field exhibit excellent correlation with east-southeast propagation of earthquake rupture and associated surface deformations. In addition, the amplitude of CIP is observed to be very small in the opposite direction of the rupture movement. Conceptual explanations on the poleward directivity of CIP exist in literature, we show the observational evidences of additional equator ward directivity, interpreted in terms of rupture propagation direction. We also discuss the coupling between earthquake induced acoustic waves and local geomagnetic field and its effects on near field CIP amplitudes. We suggest that variability of near field CIP over and near the fault plane are the manifestations of the geomagnetic field-wave coupling in addition to crustal deformations that observed through GPS measurements and corroborated by Interferometric Synthetic Aperture Radar (InSAR) data sets.

Mw7.7 2013 Balochistan Earthquake. Slip-Distribution and Deformation Field in Oblique Tectonic Context

NASA Astrophysics Data System (ADS)

Klinger, Y.; Vallage, A.; Grandin, R.; Delorme, A.; Rosu, A. M.; Pierro-Deseilligny, M.

2014-12-01

The Mw7.7 2013 Balochistan earthquake ruptured 200 km of the Hoshab fault, the southern end of the Chaman fault. Azimuth of the fault changes by more than 30° along rupture, from a well-oriented strike-slip fault to a more thrust prone direction. We use the MicMac optical image software to correlate pairs of Landsat images taken before and after the earthquake to access to the horizontal displacement field associated with the earthquake. We combine the horizontal displacement with radar image correlation in range and radar interferometry to derive the co-seismic slip on the fault. The combination of these different datasets actually provides the 3D displacement field. We note that although the earthquake was mainly strike-slip all along the rupture length, some vertical motion patches exist, which locations seem to be controlled by kilometric-scale variations of the fault geometry. 5 pairs of SPOT images were also correlated to derive a 2.5m pixel-size horizontal displacement field, providing unique opportunity to look at deformation in the near field and to obtain high-resolution strike-slip and normal slip-distributions. We note a significant difference, especially in the normal component, between the slip localized at depth on the fault plane and the slip localized closer to the surface, with more apparent slip at the surface. A high-resolution map of ground rupture allows us to locate the distribution of the deformation over the whole rupture length. The rupture map also highlights multiple fault geometric complexities where we could quantify details of the slip distribution. At the rupture length-scale, the local azimuth variations between segments have a large impact on the expression of the localized slip at the surface. The combination of those datasets gives an overview of the large distribution of the deformation in the near field, corresponding to the co-seismic damage zone.

Nonlinear interaction of strong S-waves with the rupture front in the shallow subsurface

NASA Astrophysics Data System (ADS)

Sleep, N. H.

2017-12-01

Shallow deformation in moderate to large earthquakes is sometimes distributed rather than being concentrated on a single fault plane. Strong high-frequency S-waves interact with the rupture front to produce this effect. For strike-slip faults, the rupture propagation velocity is a fraction of the S-wave velocity. The rupture propagation vector refracts essentially vertically in the low (S-wave) velocity shallow subsurface. So does the propagation direction of S-waves. The shallow rupture front is essentially mode 3 near the surface. Strong S-waves arrive before the rupture front. They continue to arrive for several seconds in a large event. There are simple scaling relationships. The dynamic Coulomb stress ratio of horizontal stress on horizontal planes from S-waves is the normalized acceleration in g's. For fractured rock and gravel, frictional failure occurs when the normalized acceleration exceeds the effective coefficient of friction. Acceleration tends to saturate at that level as the anelastic strain rate increases rapidly with stress. For muddy materials, failure begins at a low normalized acceleration but increases slowly with dynamic stress. Dynamic accelerations sometimes exceed 1 g. In both cases, the rupture tip finds the shallow subsurface already in nonlinear failure down to a few to tens of meters depth. The material does not distinguish between S-wave and rupture tip stresses. Both stresses add to the stress invariant and hence to the anelastic strain rate tensor. Surface anelastic strain from fault slip is thus distributed laterally over a distance scaling to the depth of nonlinearity from S-waves. The environs of the fault anelastically accommodate the fault slip at depth. This process differs from blind faults where the shallow coseismic strain is mostly elastic and interseismic anelastic processes accommodate the long-term shallow deformation.

Paleoearthquakes at Frazier Mountain, California delimit extent and frequency of past San Andreas Fault ruptures along 1857 trace

USGS Publications Warehouse

Scharer, Katherine M.; Weldon, Ray; Streig, Ashley; Fumal, Thomas

2014-01-01

Large earthquakes are infrequent along a single fault, and therefore historic, well-characterized earthquakes exert a strong influence on fault behavior models. This is true of the 1857 Fort Tejon earthquake (estimated M7.7–7.9) on the southern San Andreas Fault (SSAF), but an outstanding question is whether the 330 km long rupture was typical. New paleoseismic data for six to seven ground-rupturing earthquakes on the Big Bend of the SSAF restrict the pattern of possible ruptures on the 1857 stretch of the fault. In conjunction with existing sites, we show that over the last ~650 years, at least 75% of the surface ruptures are shorter than the 1857 earthquake, with estimated rupture lengths of 100 to <300 km. These results suggest that the 1857 rupture was unusual, perhaps leading to the long open interval, and that a return to pre-1857 behavior would increase the rate of M7.3–M7.7 earthquakes.

Holocene surface-faulting earthquakes at the Spring Lake and North Creek Sites on the Wasatch Fault Zone: Evidence for complex rupture of the Nephi Segment

USGS Publications Warehouse

Duross, Christopher; Hylland, Michael D.; Hiscock, Adam; Personius, Stephen; Briggs, Richard; Gold, Ryan D.; Beukelman, Gregg; McDonald, Geg N; Erickson, Ben; McKean, Adam; Angster, Steve; King, Roselyn; Crone, Anthony J.; Mahan, Shannon

2017-01-01

The Nephi segment of the Wasatch fault zone (WFZ) comprises two fault strands, the northern and southern strands, which have evidence of recurrent late Holocene surface-faulting earthquakes. We excavated paleoseismic trenches across these strands to refine and expand their Holocene earthquake chronologies; improve estimates of earthquake recurrence, displacement, and fault slip rate; and assess whether the strands rupture separately or synchronously in large earthquakes. Paleoseismic data from the Spring Lake site expand the Holocene record of earthquakes on the northern strand: at least five to seven earthquakes ruptured the Spring Lake site at 0.9 ± 0.2 ka (2σ), 2.9 ± 0.7 ka, 4.0 ± 0.5 ka, 4.8 ± 0.8 ka, 5.7 ± 0.8 ka, 6.6 ± 0.7 ka, and 13.1 ± 4.0 ka, yielding a Holocene mean recurrence of ~1.2–1.5 kyr and vertical slip rate of ~0.5–0.8 mm/yr. Paleoseismic data from the North Creek site help refine the Holocene earthquake chronology for the southern strand: at least five earthquakes ruptured the North Creek site at 0.2 ± 0.1 ka (2σ), 1.2 ± 0.1 ka, 2.6 ± 0.9 ka, 4.0 ± 0.1 ka, and 4.7 ± 0.7 ka, yielding a mean recurrence of 1.1–1.3 kyr and vertical slip rate of ~1.9–2.0 mm/yr. We compare these Spring Lake and North Creek data with previous paleoseismic data for the Nephi segment and report late Holocene mean recurrence intervals of ~1.0–1.2 kyr for the northern strand and ~1.1–1.3 kyr for the southern strand. The northern and southern strands have similar late Holocene earthquake histories, which allow for models of both independent and synchronous rupture. However, considering the earthquake timing probabilities and per-event vertical displacements, we have the greatest confidence in the simultaneous rupture of the strands, including rupture of one strand with spillover rupture to the other. Ultimately, our results improve the surface-faulting earthquake history of the Nephi segment and enhance our understanding of how structural barriers influence normal-fault rupture.

Observing Triggered Earthquakes Across Iran with Calibrated Earthquake Locations

NASA Astrophysics Data System (ADS)

Karasozen, E.; Bergman, E.; Ghods, A.; Nissen, E.

2016-12-01

We investigate earthquake triggering phenomena in Iran by analyzing patterns of aftershock activity around mapped surface ruptures. Iran has an intense level of seismicity (> 40,000 events listed in the ISC Bulletin since 1960) due to it accommodating a significant portion of the continental collision between Arabia and Eurasia. There are nearly thirty mapped surface ruptures associated with earthquakes of M 6-7.5, mostly in eastern and northwestern Iran, offering a rich potential to study the kinematics of earthquake nucleation, rupture propagation, and subsequent triggering. However, catalog earthquake locations are subject to up to 50 km of location bias from the combination of unknown Earth structure and unbalanced station coverage, making it challenging to assess both the rupture directivity of larger events and the spatial patterns of their aftershocks. To overcome this limitation, we developed a new two-tiered multiple-event relocation approach to obtain hypocentral parameters that are minimally biased and have realistic uncertainties. In the first stage, locations of small clusters of well-recorded earthquakes at local spatial scales (100s of events across 100 km length scales) are calibrated either by using near-source arrival times or independent location constraints (e.g. local aftershock studies, InSAR solutions), using an implementation of the Hypocentroidal Decomposition relocation technique called MLOC. Epicentral uncertainties are typically less than 5 km. Then, these events are used as prior constraints in the code BayesLoc, a Bayesian relocation technique that can handle larger datasets, to yield region-wide calibrated hypocenters (1000s of events over 1000 km length scales). With locations and errors both calibrated, the pattern of aftershock activity can reveal the type of the earthquake triggering: dynamic stress changes promote an increase in the seismicity rate in the direction of unilateral propagation, whereas static stress changes should not be biased by rupture propagation direction. Here we present results from Ahar, Baladeh, Qom, Rigan, Silakhour and Zirkuh clusters, that include early-instrumental and modern mainshock-aftershock sequences. These will in turn provide a greatly improved basis for research into seismic hazards in this region.

Holocene surface ruptures of the Rurrand Fault, Germany—insights from palaeoseismology, remote sensing and shallow geophysics

NASA Astrophysics Data System (ADS)

Grützner, Christoph; Fischer, Peter; Reicherter, Klaus

2016-03-01

The Lower Rhine Embayment in Central Europe hosts a rift system that has very low deformation rates. The faults in this area have slip rates of less than 0.1 mm yr-1, which does not allow to investigate ongoing tectonic deformation with geodetic techniques, unless they cover very long time spans. Instrumental seismicity does only cover a small fraction of the very long earthquake recurrence intervals of several thousands of years. Palaeoseismological studies are needed to constrain slip rates and the earthquake history of such faults. Destructive earthquakes are rare in the study area, but did occur in historic times. In 1755/1756, a series of strong earthquakes caused significant destruction in the city of Düren (Germany) and the surrounding areas. In this study we document palaeoseismological data from the nearby Rurrand Fault. In contrast to earlier studies on the same fault, we found evidence for a surface rupturing earthquake in the Holocene, and we identified at least one more surface rupturing event. Our study shows that the Rurrand Fault currently accommodates deformation in earthquakes rather than by creeping. The coseismic offsets were determined to be between less than 0.5 m per event. We assign maximum possible magnitudes of Mw 5.9-6.8 for the Rurrand Fault and a slip rate of at least 0.02-0.03 mm yr-1 for the last ˜130-50 kyr. The surface ruptures did not occur at the main fault trace that has a clear morphological expression due to older tectonic motions, but on a younger fault strand in the hanging wall of the main fault. Terrain analyses based on 1 m resolution airborne LiDAR data have been used to image the subtle morphological expression of this young fault zone. Georadar and electric resistivity tomography were applied to image the fault zone at depth and to test if these shallow geophysical methods can be used to identify and trace the fault zone. Georadar failed to produce reliable results, but geoelectrics were successfully applied and allowed us to retrieve slip rate estimates. Our results indicate that the Düren 1755/1756 earthquakes did not produce surface ruptures at the Rurrand Fault, either because they did not rupture the surface at all, or because they occurred at another, neighbouring fault.

Field and LiDAR observations of the Hector Mine California 1999 surface rupture

NASA Astrophysics Data System (ADS)

Sousa, F.; Akciz, S. O.; Harvey, J. C.; Hudnut, K. W.; Lynch, D. K.; Scharer, K. M.; Stock, J. M.; Witkosky, R.; Kendrick, K. J.; Wespestad, C.

2014-12-01

We report new field- and computer-based investigations of the surface rupture of the October 16, 1999 Hector Mine Earthquake. Since May 2012, in cooperation with the United States Marine Corps Air Ground Combat Center (MCAGCC) at Twentynine Palms, CA, our team has been allowed ground and aerial access to the entire surface rupture. We have focused our new field-based research and imagery analysis along the ~10 kilometer-long maximum slip zone (MSZ) which roughly corresponds to the zone of >4 meter dextral horizontal offset. New data include: 1) a 1 km wide aerial LiDAR survey along the entire surface rupture (@ 10 shots/m2, May 2012, www.opentopography.org); 2) terrestrial LiDAR surveys at 5 sites within the MSZ (@ >1000 shots/m2, April 2014); 3) low altitude aerial photography and ground based photography of the entire MSZ; 4) a ground-truthed database of 87 out of the 94 imagery-based offset measurements made within the MSZ; and 5) a database of 50 new field-based offset measurements made within the MSZ by our team on the ground, 31 of which have also been made on the computer (Ladicaoz) with both the 2000 LiDAR data (@ 0.5 m DEM resolution; Chen et al, in review) and 2012 LiDAR data (@ 35 cm DEM resolution; our team). New results to date include 1) significant variability (> 2 m) in horizontal offsets measured along short distances of the surface rupture (~100 m) within segments of the surface rupture that are localized to a single fault strand; 2) strong dependence of decadal scale fault scarp preservation on local lithology (bedrock vs. alluvial fan vs. fine sediment) and geomorphology (uphill vs. downhill facing scarp); 3) newly observed offset features which were never measured during the post-event field response; 4) newly observed offset features too small to be resolved in airborne LiDAR data (< 1 m); 5) nearly 25% of LiDAR imagery-based measurements that were later ground-truthed were judged by our team to warrant removal from the database due to incorrect feature reconstruction; and 6) significant variability in both accuracy of LiDAR offset measurements (relative to field-based measurements) and reported uncertainty between workers, mostly based on differing interpretations of geomorphic complexity.

The Surface faulting produced by the 30 October 2016 Mw 6.5 Central Italy earthquake: the Open EMERGEO Working Group experience

NASA Astrophysics Data System (ADS)

Pantosti, Daniela

2017-04-01

The October 30, 2016 (06:40 UTC) Mw 6.5 earthquake occurred about 28 km NW of Amatrice village as the result of upper crust normal faulting on a nearly 30 km-long, NW-SE oriented, SW dipping fault system in the Central Apennines. This earthquake is the strongest Italian seismic event since the 1980 Mw 6.9 Irpinia earthquake. The Mw 6.5 event was the largest shock of a seismic sequence, which began on August 24 with a Mw 6.0 earthquake and also included a Mw 5.9 earthquake on October 26, about 9 and 35 km NW of Amatrice village, respectively. Field surveys of coseismic geological effects at the surface started within hours of the mainshock and were carried out by several national and international teams of earth scientists (about 120 people) from different research institutions and universities coordinated by the EMERGEO Working Group of the Istituto Nazionale di Geofisica e Vulcanologia. This collaborative effort was focused on the detailed recognition and mapping of: 1) the total extent of the October 30 coseismic surface ruptures, 2) their geometric and kinematic characteristics, 3) the coseismic displacement distribution along the activated fault system, including subsidiary and antithetic ruptures. The huge amount of collected data (more than 8000 observation points of several types of coseismic effects at the surface) were stored, managed and shared using a specifically designed spreadsheet to populate a georeferenced database. More comprehensive mapping of the details and extent of surface rupture was facilitated by Structure-from-Motion photogrammetry surveys by means of several helicopter flights. An almost continuous alignment of ruptures about 30 km long, N150/160 striking, mainly SW side down was observed along the already known active Mt. Vettore - Mt. Bove fault system. The mapped ruptures occasionally overlapped those of the August 24 Mw 6.0 and October 26 Mw 5.9 shocks. The coincidence between the observed surface ruptures and the trace of active normal faults mapped in the available geological literature is noteworthy. The field data collected suggest a complex coseismic surface faulting pattern along closely-spaced, parallel or subparallel, overlapping or step-like synthetic and antithetic fault splays. The cumulative surface faulting length has been estimated in about 40 km. The maximum vertical offset is significant, locally exceeding 2 meters along the Mt. Vettore Fault, measured both along bedrock fault planes and free-faces affecting unconsolidated deposits. This enormous collaborative experience has a twofold relevance, on the one side allowed to document in high detail the earthquake ruptures before Winter would destroy them, on the other represent the first large European experience for coseismic effects survey that we should use a leading case to establish a coseismic effects European team to get ready to respond to future seismic crises at the European level.

Historic surface slip along the San Andreas Fault near Parkfield, California

USGS Publications Warehouse

Lienkaemper, J.J.; Prescott, W.H.

1989-01-01

The Parkfield Earthquake Prediction Experiment is focusing close attention on the 44-km-long section of the San Andreas fault that last ruptured seismically in 1966 (Ms 6.0). The 20-km-long central segment of the 1966 Parkfield rupture, extending from the mainshock epicenter at Middle Mountain southeastward to Gold Hill, forms a 1- to 2-km salient northeastward away from the dominant N40??W strike. Following the 1966 earthquake afterslip, aseismic slip has been nearly constant. Moderate Parkfield earthquakes have recurred on average every 21 years since 1857, when a great earthquake (M ~ 8) ruptured at least as far north as the southern Parkfield segment. Many measurements of slip have been made near Parkfield since 1966. Nevertheless, much of the history of surface slip remained uncertain, especially the total amount associated with the 1966 event. In 1985 we measured accumulated slip on the four oldest cultural features offset by the fault along the 1966 Parkfield rupture segment. -from Authors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopmann, Ch., E-mail: kerschbaum@ikv.rwth-aachen.de; Kerschbaum, M., E-mail: kerschbaum@ikv.rwth-aachen.de; Küsters, K., E-mail: kerschbaum@ikv.rwth-aachen.de

The evaluation of damages caused during processing, assembly or usage of fibre reinforced plastics is still a challenge. The use of inspection technology like ultrasonic scanning enables a detailed damage analysis but requires high investments and trained staff. Therefore, the visual inspection method is widely used. A drawback of this method is the difficult identification of barely visible damages, which can already be detrimental for the structural integrity. Therefore an approach is undertaken to integrate microencapsulated dyes into the laminates of fibre reinforced plastic parts to highlight damages on the surface. In case of a damage, the microcapsules rupture whichmore » leads to a release of the dye and a visible bruise on the part surface. To enable a wide application spectrum for this technology the microcapsules must be processable without rupturing with established manufacturing processes for fibre reinforced plastics. Therefore the incorporation of microcapsules in the filament winding, prepreg autoclave and resin transfer moulding (RTM) process is investigated. The results show that the use of a carrier medium is a feasible way to incorporate the microcapsules into the laminate for all investigated manufacturing processes. Impact testing of these laminates shows a bruise formation on the specimen surface which correlates with the impact energy level. This indicates a microcapsule survival during processing and shows the potential of this technology for damage detection and characterization.« less

XPS analysis of Al/EPDM bondlines from IUS SRM-1 polar bosses

NASA Astrophysics Data System (ADS)

Hemminger, Carol S.; Marquez, Nicholas

1993-03-01

A temperature-stress rupture method using partial immersion in liquid nitrogen was developed for the aluminum/EPDM rubber insulation bondline of the IUS SRM-1 polar bosses in order to investigate a corrosion problem. Subsequent XPS analysis of the ruptured bondline followed changes in the locus of failure as corrosion progressed. Samples from the forward polar bosses had a predominantly noncorroded appearance on the ruptured surfaces. The locus of failure was predominantly through the primer layer, which is distinguished by a high concentration of chlorinated hydrocarbon. The aft polar boss segments analyzed were characterized by the presence of corrosion over the entire mid-section of the ruptured aluminum to insulation bondline. The predominant corrosion product detected was aluminum oxide/hydroxide. The corroded bondline sections had significantly higher concentrations of aluminum oxide/hydroxide than the noncorroded areas, and lower concentrations of primer material. The temperature-stress rupture appeared to progress most readily through areas of thickened aluminum oxide/hydroxide infiltrated into the primer layer. In general there was a very good correlation between the calculated Cl:Al atomic % ratio, and the visual characterization of the extent of corrosion. The Cl:Al ratio, which represents the primer to corrosion product ratio at the locus of failure, varied from 0.4 to 47. With only a few exceptions, surfaces with a predominantly noncorroded appearance had Cl:Al ratios greater than 2, and surfaces with a heavily corroded appearance had Cl:Al ratios less than 1.

The Relationship Between Surface Curvature and Abdominal Aortic Aneurysm Wall Stress.

PubMed

de Galarreta, Sergio Ruiz; Cazón, Aitor; Antón, Raúl; Finol, Ender A

2017-08-01

The maximum diameter (MD) criterion is the most important factor when predicting risk of rupture of abdominal aortic aneurysms (AAAs). An elevated wall stress has also been linked to a high risk of aneurysm rupture, yet is an uncommon clinical practice to compute AAA wall stress. The purpose of this study is to assess whether other characteristics of the AAA geometry are statistically correlated with wall stress. Using in-house segmentation and meshing algorithms, 30 patient-specific AAA models were generated for finite element analysis (FEA). These models were subsequently used to estimate wall stress and maximum diameter and to evaluate the spatial distributions of wall thickness, cross-sectional diameter, mean curvature, and Gaussian curvature. Data analysis consisted of statistical correlations of the aforementioned geometry metrics with wall stress for the 30 AAA inner and outer wall surfaces. In addition, a linear regression analysis was performed with all the AAA wall surfaces to quantify the relationship of the geometric indices with wall stress. These analyses indicated that while all the geometry metrics have statistically significant correlations with wall stress, the local mean curvature (LMC) exhibits the highest average Pearson's correlation coefficient for both inner and outer wall surfaces. The linear regression analysis revealed coefficients of determination for the outer and inner wall surfaces of 0.712 and 0.516, respectively, with LMC having the largest effect on the linear regression equation with wall stress. This work underscores the importance of evaluating AAA mean wall curvature as a potential surrogate for wall stress.

The Gabbs Valley, Nevada, geothermal prospect: Exploring for a potential blind geothermal resource

NASA Astrophysics Data System (ADS)

Payne, J.; Bell, J. W.; Calvin, W. M.

2012-12-01

The Gabbs Valley prospect in west-central Nevada is a potential blind geothermal resource system. Possible structural controls on this system were investigated using high-resolution LiDAR, low sun-angle aerial (LSA) photography, exploratory fault trenching and a shallow temperature survey. Active Holocene faults have previously been identified at 37 geothermal systems with indication of temperatures greater than 100° C in the western Nevada region. Active fault controls in Gabbs Valley include both Holocene and historical structures. Two historical earthquakes occurring in 1932 and 1954 have overlapping surface rupture patterns in Gabbs Valley. Three active fault systems identified through LSA and LiDAR mapping have characteristics of Basin and Range normal faulting and Walker Lane oblique dextral faulting. The East Monte Cristo Mountains fault zone is an 8.5 km long continuous NNE striking, discrete fault with roughly 0.5 m right-normal historic motion and 3 m vertical Quaternary separation. The Phillips Wash fault zone is an 8.2 km long distributed fault system striking NE to N, with Quaternary fault scarps of 1-3 m vertical separation and a 500 m wide graben adjacent to the Cobble Cuesta anticline. This fault displays ponded drainages, an offset terrace riser and right stepping en echelon fault patterns suggestive of left lateral offset, and fault trenching exposed non-matching stratigraphy typical of a significant component of lateral offset. The unnamed faults of Gabbs Valley are a 10.6 km long system of normal faults striking NNE and Quaternary scarps are up to 4 m high. These normal faults largely do not have historic surface rupture, but a small segment of 1932 rupture has been identified. A shallow (2 m deep) temperature survey of 80 points covering roughly 65 square kilometers was completed. Data were collected over approximately 2 months, and continual base station temperature measurements were used to seasonally correct temperature measurements. A 2.5 km long temperature anomaly greater than 3° C above background temperatures forms west-northwest trending zone between terminations of the Phillips Wash fault zone and unnamed faults of Gabbs Valley to the south. Rupture segments of two young active faults bracket the temperature anomaly. The temperature anomaly may be due to several possible causes. 1. Increases in stress near the rupture segments or tip-lines of these faults, or where multiple fault splays exist, can increase fault permeability. The un-ruptured segments of these faults may be controlling the location of the Gabbs Valley thermal anomaly between ruptured segments of the 1932 Cedar Mountain and 1954 Fairview Peak earthquakes. 2. Numerous unnamed normal faults may interact and the hanging wall of these faults is hosting the thermal anomaly. The size and extent of the anomaly may be due to its proximity to a flat playa and not the direct location of the shallow heat anomaly. 3. The linear northwest nature of the thermal anomaly may reflect a hydrologic barrier in the subsurface controlling where heated fluids rise. A concealed NW- striking fault is possible, but has not been identified in previous studies or in the LiDAR or LSA fault mapping.

Dynamic rupture models of earthquakes on the Bartlett Springs Fault, Northern California

USGS Publications Warehouse

Lozos, Julian C.; Harris, Ruth A.; Murray, Jessica R.; Lienkaemper, James J.

2015-01-01

The Bartlett Springs Fault (BSF), the easternmost branch of the northern San Andreas Fault system, creeps along much of its length. Geodetic data for the BSF are sparse, and surface creep rates are generally poorly constrained. The two existing geodetic slip rate inversions resolve at least one locked patch within the creeping zones. We use the 3-D finite element code FaultMod to conduct dynamic rupture models based on both geodetic inversions, in order to determine the ability of rupture to propagate into the creeping regions, as well as to assess possible magnitudes for BSF ruptures. For both sets of models, we find that the distribution of aseismic creep limits the extent of coseismic rupture, due to the contrast in frictional properties between the locked and creeping regions.

In vivo serial MRI-based models and statistical methods to quantify sensitivity and specificity of mechanical predictors for carotid plaque rupture: location and beyond.

PubMed

Wu, Zheyang; Yang, Chun; Tang, Dalin

2011-06-01

It has been hypothesized that mechanical risk factors may be used to predict future atherosclerotic plaque rupture. Truly predictive methods for plaque rupture and methods to identify the best predictor(s) from all the candidates are lacking in the literature. A novel combination of computational and statistical models based on serial magnetic resonance imaging (MRI) was introduced to quantify sensitivity and specificity of mechanical predictors to identify the best candidate for plaque rupture site prediction. Serial in vivo MRI data of carotid plaque from one patient was acquired with follow-up scan showing ulceration. 3D computational fluid-structure interaction (FSI) models using both baseline and follow-up data were constructed and plaque wall stress (PWS) and strain (PWSn) and flow maximum shear stress (FSS) were extracted from all 600 matched nodal points (100 points per matched slice, baseline matching follow-up) on the lumen surface for analysis. Each of the 600 points was marked "ulcer" or "nonulcer" using follow-up scan. Predictive statistical models for each of the seven combinations of PWS, PWSn, and FSS were trained using the follow-up data and applied to the baseline data to assess their sensitivity and specificity using the 600 data points for ulcer predictions. Sensitivity of prediction is defined as the proportion of the true positive outcomes that are predicted to be positive. Specificity of prediction is defined as the proportion of the true negative outcomes that are correctly predicted to be negative. Using probability 0.3 as a threshold to infer ulcer occurrence at the prediction stage, the combination of PWS and PWSn provided the best predictive accuracy with (sensitivity, specificity) = (0.97, 0.958). Sensitivity and specificity given by PWS, PWSn, and FSS individually were (0.788, 0.968), (0.515, 0.968), and (0.758, 0.928), respectively. The proposed computational-statistical process provides a novel method and a framework to assess the sensitivity and specificity of various risk indicators and offers the potential to identify the optimized predictor for plaque rupture using serial MRI with follow-up scan showing ulceration as the gold standard for method validation. While serial MRI data with actual rupture are hard to acquire, this single-case study suggests that combination of multiple predictors may provide potential improvement to existing plaque assessment schemes. With large-scale patient studies, this predictive modeling process may provide more solid ground for rupture predictor selection strategies and methods for image-based plaque vulnerability assessment.

The Wasatch fault zone, utah-segmentation and history of Holocene earthquakes

USGS Publications Warehouse

Machette, M.N.; Personius, S.F.; Nelson, A.R.; Schwartz, D.P.; Lund, W.R.

1991-01-01

The Wasatch fault zone (WFZ) forms the eastern boundary of the Basin and Range province and is the longest continuous, active normal fault (343 km) in the United States. It underlies an urban corridor of 1.6 million people (80% of Utah's population) representing the largest earthquake risk in the interior of the western United States. We have used paleoseismological data to identify 10 discrete segments of the WFZ. Five are active, medial segments with Holocene slip rates of 1-2 mm a-1, recurrence intervals of 2000-4000 years and average lengths of about 50 km. Five are less active, distal segments with mostly pre-Holocene surface ruptures, late Quaternary slip rates of 6.5 have occurred since 1860. Although the time scale of the clustering is different-130 years vs 1100 years-we consider the central Nevada-eastern California Seismic Belt to be a historic analog for movement on the WFZ during the past 1500 years. We have found no evidence that surface-rupturing events occurred on the WFZ during the past 400 years, a time period which is twice the average intracluster recurrence interval and equal to the average Holocene recurrence interval. In particular, the Brigham City segment (the northernmost medial segment) has not ruptured in the past 3600 years-a period that is about three times longer than this segment's average recurrence interval during the early and middle Holocene. Although the WFZ's seismological record is one of relative quiescence, a comparison with other historic surface-rupturing earthquakes in the region suggests that earthquakes having moment magnitudes of 7.1-7.4 (or surface-wave magnitudes of 7.5-7.7)-each associated with tens of kilometers of surface rupture and several meters of normal dip slip-have occurred about every four centuries during the Holocene and should be expected in the future. ?? 1991.

Aftershocks of the june 20, 1978, Greece earthquake: A multimode faulting sequence

USGS Publications Warehouse

Carver, D.; Bollinger, G.A.

1981-01-01

A 10-station portable seismograph network was deployed in northern Greece to study aftershocks of the magnitude (mb) 6.4 earthquake of June 20, 1978. The main shock occurred (in a graben) about 25 km northeast of the city of Thessaloniki and caused an east-west zone of surface rupturing 14 km long that splayed to 7 km wide at the west end. The hypocenters for 116 aftershocks in the magnitude range from 2.5 to 4.5 were determined. The epicenters for these events cover an area 30 km (east-west) by 18 km (north-south), and focal depths ranges from 4 to 12 km. Most of the aftershocks in the east half of the aftershock zone are north of the surface rupture and north of the graben. Those in the west half are located within the boundaries of the graben. Composite focalmechanism solutions for selected aftershocks indicate reactivation of geologically mapped normal faults in the area. Also, strike-slip and dip-slip faults that splay off the western end of the zone of surface ruptures may have been activated. The epicenters for four large (M ??? 4.8) foreshocks and the main shock were relocated using the method of joint epicenter determination. Collectively, those five epicenters form an arcuate pattern convex southward, that is north of and 5 km distant from the surface rupturing. The 5-km separation, along with a focal depth of 8 km (average aftershock depth) or 16 km (NEIS main-shock depth), implies that the fault plane dips northward 58?? or 73??, respectively. A preferred nodal-plane dip of 36?? was determined by B.C. Papazachos and his colleagues in 1979 from a focal-mechanism solution for the main shock. If this dip is valid for the causal fault and that fault projects to the zone of surface rupturing, a decrease of dip with depth is required. ?? 1981.

Crack propagation in disordered materials: how to decipher fracture surfaces

NASA Astrophysics Data System (ADS)

Ponson, L.

For a half-century, engineers know how to describe and predict the propagation of a crack in a model elastic homogeneous medium. The case of real materials is much more complex. Indeed, we do not know how to relate their lifetime or their resistance to their microstructure. To achieve such a prediction, understanding the role of the microstructural disorder on the behavior of a crack is determinant. Fracture surfaces represent a promising field of investigation to address this question. From the study of various disordered materials, we propose a statistical description of their roughness and determine to which extent their properties are dependent of the material. We show that fracture surfaces display an anisotropic scale invariant geometry characterized by two universal exponents. Glass ceramics is then studied because its microstructure can be tuned in a controlled manner. Their fracture surfaces display the same general anisotropic properties but with surprisingly low exponents independent of the detail of the ceramics microstructure. This suggests the existence of a second universality class in failure problems. Using finally theoretical tools from out-of-equilibrium statistical physics and fracture mechanics, we relate the statistical properties of fracture surfaces with the mechanisms occurring at the microscopic scale during the failure of a material. In particular, we show that the first class of fracture surfaces results from a failure involving damage processes while the second one results from a perfectly brittle failure. Propagation de fissures dans les matériaux désordonnés : comment déchiffrer les surfaces de rupture. Depuis près d'un demi-siècle, les ingénieurs savent décrire et prévoir la propagation d'une fissure dans un milieu élastique homogène modèle. Le cas des matériaux réels est beaucoup plus complexe. En effet, on ne sait pas relier leur durée de vie ou leur résistance à leur microstructure. Passage obligé avant de telles prédictions, il est nécessaire de comprendre comment le désordre structural du matériau influe sur le comportement d'une fissure. Dans cette optique, les surfaces de rupture représentent un champ d'investigation très prometteur. À travers une étude portant sur divers matériaux hétérogènes, nous caractérisons les propriétés statistiques de leur rugosité et déterminons dans quelle mesure elles sont indépendantes du matériau. Nous montrons notamment que les surfaces de rupture présentent des propriétés d'invariance d'échelle anisotropes, caractérisées par deux exposants universels. Étudiant ensuite une céramique de verre, matériau hétérogène modèle dont on peut contrôler la microstructure, on montre qu'il existe une seconde classe de surfaces de rupture caractérisée par la même structure anisotrope mais présentant des exposants plus faibles. Utilisant enfin des outils théoriques issus de la physique statistique hors équilibre combinés avec la mécanique de la rupture, nous établissons le lien entre ces propriétés et les mécanismes généraux de rupture à l'échelle microscopique. Cette étude nous permet notamment d'associer les deux classes de surfaces de rupture à un processus de fissuration mettant en jeux de l'endommagement pour l'un et à une rupture parfaitement fragile pour l'autre.

Real-Time Detection of Rupture Development: Earthquake Early Warning Using P Waves From Growing Ruptures

NASA Astrophysics Data System (ADS)

Kodera, Yuki

2018-01-01

Large earthquakes with long rupture durations emit P wave energy throughout the rupture period. Incorporating late-onset P waves into earthquake early warning (EEW) algorithms could contribute to robust predictions of strong ground motion. Here I describe a technique to detect in real time P waves from growing ruptures to improve the timeliness of an EEW algorithm based on seismic wavefield estimation. The proposed P wave detector, which employs a simple polarization analysis, successfully detected P waves from strong motion generation areas of the 2011 Mw 9.0 Tohoku-oki earthquake rupture. An analysis using 23 large (M ≥ 7) events from Japan confirmed that seismic intensity predictions based on the P wave detector significantly increased lead times without appreciably decreasing the prediction accuracy. P waves from growing ruptures, being one of the fastest carriers of information on ongoing rupture development, have the potential to improve the performance of EEW systems.

No difference between mechanical perturbation training with compliant surface and manual perturbation training on knee functional performance after ACL rupture.

PubMed

Nawasreh, Zakariya; Logerstedt, David; Failla, Mathew; Snyder-Mackler, Lynn

2017-10-27

Manual perturbation training improves dynamic knee stability and functional performance after anterior cruciate ligament rupture (ACL-rupture). However, it is limited to static standing position and does not allow time-specific perturbations at different phase of functional activities. The purpose of this study was to investigate whether administering mechanical perturbation training including compliant surface provides effects similar to manual perturbation training on knee functional measures after an acute ACL-rupture. Sixteen level I/II athletes with ACL-ruptures participated in this preliminary study. Eight patients received mechanical (Mechanical) and eight subjects received manual perturbation training (Manual). All patients completed a functional testing (isometric quadriceps strength, single-legged hop tests) and patient-reported measures (Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS), Global Rating Score (GRS), International Knee Documentation Committee 2000 (IKDC 2000) at pre- and post-training. 2 × 2 ANOVA was used for data analysis. No significant group-by-time interactions were found for all measures (p > 0.18). Main effects of time were found for single hop (Pre-testing: 85.14% ± 21.07; Post-testing: 92.49% ± 17.55), triple hop (Pre-testing: 84.64% ± 14.17; Post-testing: 96.64% ± 11.14), KOS-ADLS (Pre-testing: 81.13% ± 11.12; Post-testing: 88.63% ± 12.63), GRS (Pre-testing: 68.63% ± 15.73; Post-testing: 78.81% ± 13.85), and IKDC 2000 (Pre-testing: 66.66% ± 9.85; Post-testing: 76.05% ± 14.62) (p < 0.032). Administering mechanical perturbation training using compliant surfaces induce effects similar to manual perturbation training on knee functional performance after acute ACL-rupture. The clinical significance is both modes of training improve patients' functional-performance and limb-to-limb movement symmetry, and enhancing the patients' self-reported of knee functional measures after ACL rupture. Mechanical perturbation that provides a compliant surface might be utilized as part of the ACL rehabilitation training. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Could offset cluster reveal strong earthquake pattern?——case study from Haiyuan Fault

NASA Astrophysics Data System (ADS)

Ren, Z.; Zhang, Z.; Chen, T.; Yin, J.; Zhang, P. Z.; Zheng, W.; Zhang, H.; Li, C.

2016-12-01

Since 1990s, researchers tried to use offset clusters to study strong earthquake patterns. However, due to the limitation of quantity of offset data, it was not widely used until recent years with the rapid development of high-resolution topographic data, such as remote sensing images, LiDAR. In this study, we use airborne LiDAR data to re-evaluate the cumulative offsets and co-seismic offset of the 1920 Haiyuan Ms 8.5 earthquake along the western and middle segments of the co-seismic surface rupture zone. Our LiDAR data indicate the offset observations along both the western and middle segments fall into five groups. The group with minimum slip amount is associated with the 1920 Haiyuan Ms 8.5 earthquake, which ruptured both the western and middle segments. Our research highlights two new interpretations: firstly, the previously reported maximum displacement of the 1920 Earthquake is likely to be produced by at least two earthquakes; secondly, Our results reveal that the Cumulative Offset Probability Density (COPD) peaks of same offset amount on western segment and middles segment did not corresponding to each other one by one. The ages of the paleoearthquakes indicate the offsets are not accumulated during same period. We suggest that any discussion of the rupture pattern of a certain fault based on the offset data should also consider fault segmentation and paleoseismological data; Therefore, using the COPD peaks for studying the number of palaeo-events and their rupture patterns, the COPD peaks should be computed and analyzed on fault sub-sections and not entire fault zones. Our results reveal that the rupture pattern on the western and middle segment of the Haiyuan Fault is different from each other, which provide new data for the regional seismic potential analysis.

Persistent rupture terminations at a restraining bend from slip rates on the eastern Altyn Tagh fault

NASA Astrophysics Data System (ADS)

Elliott, A. J.; Oskin, M. E.; Liu-zeng, J.; Shao, Y.-X.

2018-05-01

Restraining double-bends along strike-slip faults inhibit or permit throughgoing ruptures depending on bend angle, length, and prior rupture history. Modeling predicts that for mature strike-slip faults in a regional stress regime characterized by simple shear, a restraining bend of >18° and >4 km length impedes propagating rupture. Indeed, natural evidence shows that the most recent rupture(s) of the Xorkoli section (90°-93°E) of the eastern Altyn Tagh fault (ATF) ended at large restraining bends. However, when multiple seismic cycles are considered in numerical dynamic rupture modeling, heterogeneous residual stresses enable some ruptures to propagate further, modulating whether the bends persistently serve as barriers. These models remain to be tested using observations of the cumulative effects of multiple earthquake ruptures. Here we investigate whether a large restraining double-bend on the ATF serves consistently as a barrier to rupture by measuring long-term slip rates around the terminus of its most recent surface rupture at the Aksay bend. Our results show a W-E decline in slip as the SATF enters the bend, as would be predicted from repeated rupture terminations there. Prior work demonstrated no Holocene slip on the central, most misoriented portion of the bend, while 19-79 m offsets suggest that multiple ruptures have occurred on the west side of the bend during the Holocene. Thus we conclude the gradient in the SATF's slip rate results from the repeated termination of earthquake ruptures there. However, a finite slip rate east of the bend represents the transmission of some slip, suggesting that a small fraction of ruptures may fully traverse or jump the double-bend. This agreement between natural observations of slip accumulation and multi-cycle models of fault rupture enables us to translate observed slip rates into insight about the dynamic rupture process of individual earthquakes as they encounter geometric complexities along faults.

A method and example of seismically imaging near‐surface fault zones in geologically complex areas using Vp, Vs, and their ratios

USGS Publications Warehouse

Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R.; Sickler, Robert R.; Criley, Coyn J.

2014-01-01

The determination of near‐surface (vadose zone and slightly below) fault locations and geometries is important because assessment of ground rupture, strong shaking, geologic slip rates, and rupture histories occurs at shallow depths. However, seismic imaging of fault zones at shallow depths can be difficult due to near‐surface complexities, such as weathering, groundwater saturation, massive (nonlayered) rocks, and vertically layered strata. Combined P‐ and S‐wave seismic‐refraction tomography data can overcome many of the near‐surface, fault‐zone seismic‐imaging problems because of differences in the responses of elastic (bulk and shear) moduli of P and S waves to shallow‐depth, fault‐zone properties. We show that high‐resolution refraction tomography images of P‐ to S‐wave velocity ratios (VP/VS) can reliably identify near‐surface faults. We demonstrate this method using tomography images of the San Andreas fault (SAF) surface‐rupture zone associated with the 18 April 1906 ∼M 7.9 San Francisco earthquake on the San Francisco peninsula in California. There, the SAF cuts through Franciscan mélange, which consists of an incoherent assemblage of greywacke, chert, greenstone, and serpentinite. A near‐vertical zone (∼75° northeast dip) of high P‐wave velocities (up to 3000  m/s), low S‐wave velocities (∼150–600  m/s), high VP/VS ratios (4–8.8), and high Poisson’s ratios (0.44–0.49) characterizes the main surface‐rupture zone to a depth of about 20 m and is consistent with nearby trench observations. We suggest that the combined VP/VSimaging approach can reliably identify most near‐surface fault zones in locations where many other seismic methods cannot be applied.

Surface faulting along the inland Itozawa normal fault (eastern Japan) and relation to the 2011 Tohoku-oki megathrust earthquake

NASA Astrophysics Data System (ADS)

Ferry, M.; Tsutsumi, H.; Meghraoui, M.; Toda, S.

2012-12-01

The 11 March 2011 Mw 9 Tohoku-oki earthquake ruptured ~500 km length of the Japan Trench along the coast of eastern Japan and significantly impacted the stress regime within the crust. The resulting change in seismicity over the Japan mainland was exhibited by the 11 April 2011 Mw 6.6 Iwaki earthquake that ruptured the Itozawa and Yunodake faults. Trending NNW and NW, respectively, these 70-80° W-dipping faults bound the Iwaki basin of Neogene age and have been reactivated simultaneously both along 15-km-long sections. Here, we present initial results from a paleoseismic excavation performed across the Itozawa fault within the Tsunagi Valley at the northern third of the observed surface rupture. At the Tsunagi site, the rupture affects a rice paddy, which provides an ideally horizontal initial state to collect detailed and accurate measurements. The surface break is composed of a continuous 30-to-40-cm-wide purely extensional crack that separates the uplifted block from a gently dipping 1-to-2-m-wide strip affected by right-stepping en-echelon cracks and locally bounded by a ~0.1-m-high reverse scarplet. Total station across-fault topographic profiles indicate the pre-earthquake ground surface was vertically deformed by ~0.6 m while direct field examinations reveal that well-defined rice paddy limits have been left-laterally offset by ~0.1 m. The 12-m-long, 3.5-m-deep trench exposes the 30-to-40-cm-thick cultivated soil overlaying a 1-m-thick red to yellow silt unit, a 2-m-thick alluvial gravel unit and a basal 0.1-1-m-thick organic-rich silt unit. Deformation associated to the 2011 rupture illustrates down-dip movement along a near-vertical fault with a well-expressed bending moment at the surface and generalized warping. On the north wall, the intermediate gravel unit displays a deformation pattern similar to granular flow with only minor discrete faulting and no splay to be continuously followed from the main fault to the surface. On the south wall, warping dominates as well but with some strain localization along two major splays that exhibit 15-20 cm of vertical offset. On both walls, the basal silt unit is vertically deformed by ~0.6 m, similarly to what is observed for the 2011 rupture. Furthermore, the base of said silt unit exhibits indication for secondary faulting prior to the 2011 event and that resemble cracks observed at the present-day surface. This suggests that the Itozawa fault has already ruptured in a similar fashion; probably in the late Pleistocene-early Holocene (radiocarbon samples are being processed). Hence, recent activity of the Itozawa fault may be controlled entirely by large to giant earthquakes along the Japan Trench.

Pulsed strain release on the Altyn Tagh fault, northwest China

USGS Publications Warehouse

Gold, Ryan D.; Cowgill, Eric; Arrowsmith, J. Ramón; Friedrich, Anke M.

2017-01-01

Earthquake recurrence models assume that major surface-rupturing earthquakes are followed by periods of reduced rupture probability as stress rebuilds. Although purely periodic, time- or slip-predictable rupture models are known to be oversimplifications, a paucity of long records of fault slip clouds understanding of fault behavior and earthquake recurrence over multiple ruptures. Here, we report a 16 kyr history of fault slip—including a pulse of accelerated slip from 6.4 to 6.0 ka—determined using a Monte Carlo analysis of well-dated offset landforms along the central Altyn Tagh strike-slip fault (ATF) in northwest China. This pulse punctuates a median rate of 8.1+1.2/−0.9 mm/a and likely resulted from either a flurry of temporally clustered ∼Mw 7.5 ground-rupturing earthquakes or a single large >Mw 8.2 earthquake. The clustered earthquake scenario implies rapid re-rupture of a fault reach >195 km long and indicates decoupled rates of elastic strain energy accumulation versus dissipation, conceptualized as a crustal stress battery. If the pulse reflects a single event, slip-magnitude scaling implies that it ruptured much of the ATF with slip similar to, or exceeding, the largest documented historical ruptures. Both scenarios indicate fault rupture behavior that deviates from classic time- or slip-predictable models.

Identification of vortex structures in a cohort of 204 intracranial aneurysms

PubMed Central

Trylesinski, Gabriel; Xiang, Jianping; Snyder, Kenneth; Meng, Hui

2017-01-01

An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured). Using objective quantities to identify three-dimensional vortex structures, we investigated the characteristics associated with aneurysm rupture and if these features correlate with previously proposed WSS and morphological characteristics indicative of IA rupture. Based on the Q-criterion definition of a vortex, we quantified the degree of the aneurysmal region occupied by vortex structures using the volume vortex fraction (vVF) and the surface vortex fraction (sVF). Computational fluid dynamics simulations showed that the sVF, but not the vVF, discriminated ruptured from unruptured aneurysms. Furthermore, we found that the near-wall vortex structures co-localized with regions of inflow jet breakdown, and significantly correlated to previously proposed haemodynamic and morphologic characteristics of ruptured IAs. PMID:28539480

Identification of vortex structures in a cohort of 204 intracranial aneurysms.

PubMed

Varble, Nicole; Trylesinski, Gabriel; Xiang, Jianping; Snyder, Kenneth; Meng, Hui

2017-05-01

An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured). Using objective quantities to identify three-dimensional vortex structures, we investigated the characteristics associated with aneurysm rupture and if these features correlate with previously proposed WSS and morphological characteristics indicative of IA rupture. Based on the Q -criterion definition of a vortex, we quantified the degree of the aneurysmal region occupied by vortex structures using the volume vortex fraction ( vVF ) and the surface vortex fraction ( sVF ). Computational fluid dynamics simulations showed that the sVF , but not the vVF , discriminated ruptured from unruptured aneurysms. Furthermore, we found that the near-wall vortex structures co-localized with regions of inflow jet breakdown, and significantly correlated to previously proposed haemodynamic and morphologic characteristics of ruptured IAs. © 2017 The Author(s).

Wasatch fault zone, Utah - segmentation and history of Holocene earthquakes

USGS Publications Warehouse

Machette, Michael N.; Personius, Stephen F.; Nelson, Alan R.; Schwartz, David P.; Lund, William R.

1991-01-01

The Wasatch fault zone (WFZ) forms the eastern boundary of the Basin and Range province and is the longest continuous, active normal fault (343 km) in the United States. It underlies an urban corridor of 1.6 million people (80% of Utah's population) representing the largest earthquake risk in the interior of the western United States. The authors have used paleoseismological data to identify 10 discrete segments of the WFZ. Five are active, medial segments with Holocene slip rates of 1-2 mm a-1, recurrence intervals of 2000-4000 years and average lengths of about 50 km. Five are less active, distal segments with mostly pre-Holocene surface ruptures, late Quaternary slip rates of <0.5 mm a-1, recurrence intervals of ???10,000 years and average lengths of about 20 km. Surface-faulting events on each of the medial segments of the WFZ formed 2-4-m-high scarps repeatedly during the Holocene. Paleoseismological records for the past 6000 years indicate that a major surface-rupturing earthquake has occurred along one of the medial segments about every 395 ?? 60 years. However, between about 400 and 1500 years ago, the WFZ experienced six major surface-rupturing events, an average of one event every 220 years, or about twice as often as expected from the 6000-year record. Evidence has been found that surface-rupturing events occurred on the WFZ during the past 400 years, a time period which is twice the average intracluster recurrence interval and equal to the average Holocene recurrence interval.

Snap, Crackle, Pop: Dilational fault breccias record seismic slip below the brittle-plastic transition

NASA Astrophysics Data System (ADS)

Melosh, Ben L.; Rowe, Christie D.; Smit, Louis; Groenewald, Conrad; Lambert, Christopher W.; Macey, Paul

2014-10-01

Off-fault dynamic tensile cracks form behind an earthquake rupture front with distinct orientation and spacing. These cracks explode the wall rock and create breccias, which we hypothesize will preserve a unique fingerprint of dynamic rupture. Identification of these characteristic breccias may enable a new tool for identifying paleoseismic slip surfaces in the rock record. Using previous experimental and theoretical predictions, we develop a field-based model of dynamic dilational breccia formation. Experimental studies find that secondary tensile fracture networks comprise closely spaced fractures at angles of 70-90° from a slip surface, as well as fractures that branch at angles of ∼ 30 ° from a primary mode I fracture. The Pofadder Shear Zone, in Namibia and South Africa, preserves breccias formed in the brittle-ductile transition zone displaying fracture patterns consistent with those described above. Fracture spacing is approximately two orders of magnitude less than predicted by quasi-static models. Breccias are clast-supported, monomict and can display an abrupt transition from fracture network crackle breccia to mosaic breccia textures. Brecciation occurs by the intersection of off-fault dynamic fractures and wall rock fabric; this is in contrast to previous models of fluid pressure gradient-driven failure ;implosion breccias;. This mechanism tends to form many similar sized clasts with particle size distributions that may not display self-similarity; where self-similarity is observed the distributions have relatively low D-values of 1.47 ± 0.37, similar to other studies of dynamic processes. We measure slip distances at dilational breccia stepovers, estimating earthquake magnitudes between Mw 2.8-5.8 and associated rupture lengths of 0.023-3.3 km. The small calculated rupture dimensions, in combination with our geologic observations, suggest that some earthquakes nucleated within the quartz-plastic transitional zone and potentially record deep seismic slip.

Slip model of the 2015 Mw 7.8 Gorkha (Nepal) earthquake from inversions of ALOS-2 and GPS data

NASA Astrophysics Data System (ADS)

Wang, Kang; Fialko, Yuri

2015-09-01

We use surface deformation measurements including Interferometric Synthetic Aperture Radar data acquired by the ALOS-2 mission of the Japanese Aerospace Exploration Agency and Global Positioning System (GPS) data to invert for the fault geometry and coseismic slip distribution of the 2015 Mw 7.8 Gorkha earthquake in Nepal. Assuming that the ruptured fault connects to the surface trace of the Main Frontal Thrust (MFT) fault between 84.34°E and 86.19°E, the best fitting model suggests a dip angle of 7°. The moment calculated from the slip model is 6.08 × 1020 Nm, corresponding to the moment magnitude of 7.79. The rupture of the 2015 Gorkha earthquake was dominated by thrust motion that was primarily concentrated in a 150 km long zone 50 to 100 km northward from the surface trace of the Main Frontal Thrust (MFT), with maximum slip of ˜ 5.8 m at a depth of ˜8 km. Data thus indicate that the 2015 Gorkha earthquake ruptured a deep part of the seismogenic zone, in contrast to the 1934 Bihar-Nepal earthquake, which had ruptured a shallow part of the adjacent fault segment to the east.

Interfacial thin films rupture and self-similarity

NASA Astrophysics Data System (ADS)

Ward, Margaret H.

2011-06-01

Two superposed thin layers of fluids are prone to interfacial instabilities due to London-van der Waals forces. Evolution equations for the film thicknesses are derived using lubrication theory. Using the intrinsic scales, for a single layer, results in a system with parametric dependence of four ratios of the two layers: surface tension, Hamaker constant, viscosity, and film thickness. In contrast to the single layer case, the bilayer system has two unstable eigenmodes: squeezing and bending. For some particular parameter regimes, the system exhibits the avoided crossing behavior, where the two eigenmodes are interchanged. Based on numerical analysis, the system evolves into four different rupture states: basal layer rupture, upper layer rupture, double layer rupture, and mixed layer rupture. The ratio of Hamaker constants and the relative film thickness of the two layers control the system dynamics. Remarkably, the line of avoided crossing demarks the transition region of mode mixing and energy transfer, affecting the scaling of the dynamical regime map consequentially. Asymptotic and numerical analyses are used to examine the self-similar ruptures and to extract the power law scalings for both the basal layer rupture and the upper layer rupture. The scaling laws for the basal layer rupture are the same as those of the single layer on top of a substrate. The scaling laws for the upper layer rupture are different: the lateral length scale decreases according to (tr-t)1/3 and the film thickness decreases according to (tr-t)1/6.

Plasmodium falciparum antigens synthesized by schizonts and stabilized at the merozoite surface by antibodies when schizonts mature in the presence of growth inhibitory immune serum.

PubMed

Lyon, J A; Haynes, J D; Diggs, C L; Chulay, J D; Pratt-Rossiter, J M

1986-03-15

Some immune sera that inhibit erythrocyte invasion by merozoites also agglutinate the merozoites as they emerge from rupturing schizonts. These immune clusters of merozoites (ICM) possess a surface coat that is cross-linked by antibody and is thicker than the surface coat associated with normal merozoites (NM) obtained from cultures containing preimmune serum. Analysis of metabolically labeled ICM and NM performed by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that washed ICM possessed immune complexes containing antigens representative of schizonts and merozoites. Characteristics of the immune complexes included: a) they were not soluble in pH 8 Triton X-100, b) they were soluble at an acid pH, and c) after pH neutralization they were precipitated by using staphylococcal protein A. Merozoite antigens having Mr of 83, 73, and 45 kDa were associated with immune complexes in ICM. The 83 and 73 kDa antigens were recovered in considerably larger quantities from ICM than from NM. Schizont antigens having Mr of 230, 173 (triplet), 152 (doublet), and 31 kDa were associated with immune complexes in ICM, and a 195 kDa antigen(s) from schizonts and merozoites was also present in the immune complexes. In addition, other antigens of Mr 113, 101, 65, and 51 kDa may have been immune complexed. These 15 antigens accounted for less than 30% of the schizont and merozoite antigens recognized by the immune serum. Immune complexes probably formed between antibodies and a) surface antigens of schizont-infected erythrocytes exposed to antibody before schizont rupture, b) surface antigens of merozoites and schizonts exposed during schizont rupture, and c) soluble antigens normally released during schizont rupture. The antibody components of the immune complexes may have prevented rapid degradation or shedding of some antigens from the merozoite surface. Allowing schizonts to rupture in the presence of inhibitory antibodies (to form ICM) is a useful approach to identifying exposed targets of protective immunity against malaria.

Comparison of the November 2002 Denali and November 2001 Kunlun Earthquakes

NASA Astrophysics Data System (ADS)

Bufe, C. G.

2002-12-01

Major earthquakes occurred in Tibet on the central Kunlun fault (M 7.8) on November 14, 2001 (Lin and others, 2002) and in Alaska on the central Denali fault (M 7.9) on November 3, 2002. Both earthquakes generated large surface waves (Kunlun Ms 8.0 (USGS) and Denali Ms 8.5). Each event occurred on east-west-trending strike-slip faults and exhibited nearly unilateral rupture propagating several hundred kilometers from west to east. Surface rupture length estimates were about 400 km for Kunlun, 300 km for Denali. Maximum surface faulting and moment release were observed far to the east of the points of rupture initiation. Harvard moment centroids were located east of USGS epicenters by 182 km (Kunlun) and by 126 km (Denali). Maximum surface faulting was observed near 240 km (Kunlun, 16 m left lateral) and near 175 km (Denali, 9 m right lateral) east of the USGS epicenters. Significant thrust components were observed in the initiation of the Denali event (ERI analysis and mapped thrust) and in the termination of the Kunlun rupture, as evidenced by thrust mechanisms of the largest aftershocks which occurred near the eastern part of the Kunlun rupture. In each sequence the largest aftershock was about 2 orders of magnitude smaller than the mainshock. Moment release along the ruptured segments was examined for the 25-year periods preceding the main shocks. The Denali zone shows precursory accelerating moment release with the dominant events occurring on October 22, 1996 (M 5.8) and October 23, 2002 (M 6.7). The Kunlun zone shows nearly constant moment release over time with the last significant event before the main shock occurring on November 26, 2000 (M 5.4). Moment release data are consistent with previous observations of annual periodicity preceding major earthquakes, possibly due to the evolution of a critical state with seasonal and tidal triggering (Varnes and Bufe, 2001). Annual periodicity is also evident for the larger events in the greater San Francisco Bay region over several decades preceding the 1906 San Francisco earthquake (M 7.8). Both the Kunlun and the Denali mainshocks occurred at new moon.

The Wasatch fault zone, utah—segmentation and history of Holocene earthquakes

NASA Astrophysics Data System (ADS)

Machette, Michael N.; Personius, Stephen F.; Nelson, Alan R.; Schwartz, David P.; Lund, William R.

The Wasatch fault zone (WFZ) forms the eastern boundary of the Basin and Range province and is the longest continuous, active normal fault (343 km) in the United States. It underlies an urban corridor of 1.6 million people (80% of Utah's population) representing the largest earthquake risk in the interior of the western United States. We have used paleoseismological data to identify 10 discrete segments of the WFZ. Five are active, medial segments with Holocene slip rates of 1-2 mm a -1, recurrence intervals of 2000-4000 years and average lengths of about 50 km. Five are less active, distal segments with mostly pre-Holocene surface ruptures, late Quaternary slip rates of <0.5 mm a -1 recurrence intervals of ≥10,000 years and average lengths of about 20 km. Surface-faulting events on each of the medial segments of the WFZ formed 2-4-m-high scarps repeatedly during the Holocene; latest Pleistocene (14-15 ka) deposits commonly have scarps as much as 15-20 m in height. Segments identified from paleoseismological studies of other major late Quaternary normal faults in the northern Basin and Range province are 20-25 km long, or about half of that proposed for the medial segments of the WFZ. Paleoseismological records for the past 6000 years indicate that a major surface-rupturing earthquake has occurred along one of the medial segments about every 395 ± 60 years. However, between about 400 and 1500 years ago, the WFZ experienced six major surface-rupturing events, an average of one event every 220 years, or about twice as often as expected from the 6000-year record. This pattern of temporal clustering is similar to that of the central Nevada—eastern California Seismic Belt in the western part of the Basin and Range province, where 11 earthquakes of M > 6.5 have occurred since 1860. Although the time scale of the clustering is different—130 years vs 1100 years—we consider the central Nevada—eastern California Seismic Belt to be a historic analog for movement on the WFZ during the past 1500 years. We have found no evidence that surface-rupturing events occurred on the WFZ during the past 400 years, a time period which is twice the average intracluster recurrence interval and equal to the average Holocene recurrence interval. In particular, the Brigham City segment (the northernmost medial segment) has not ruptured in the past 3600 years—a period that is about three times longer than this segment's average recurrence interval during the early and middle Holocene. Although the WFZ's seismological record is one of relative quiescence, a comparison with other historic surface-rupturing earthquakes in the region suggests that earthquakes having moment magnitudes of 7.1-7.4 (or surface-wave magnitudes of 7.5-7.7)—each associated with tens of kilometers of surface rupture and several meters of normal dip slip—have occurred about every four centuries during the Holocene and should be expected in the future.

Surface faulting along the Superstition Hills fault zone and nearby faults associated with the earthquakes of 24 November 1987

USGS Publications Warehouse

Sharp, R.V.

1989-01-01

The M6.2 Elmore Desert Ranch earthquake of 24 November 1987 was associated spatially and probably temporally with left-lateral surface rupture on many northeast-trending faults in and near the Superstition Hills in western Imperial Valley. Three curving discontinuous principal zones of rupture among these breaks extended northeastward from near the Superstition Hills fault zone as far as 9km; the maximum observed surface slip, 12.5cm, was on the northern of the three, the Elmore Ranch fault, at a point near the epicenter. Twelve hours after the Elmore Ranch earthquake, the M6.6 Superstition Hills earthquake occurred near the northwest end of the right-lateral Superstition Hills fault zone. We measured displacements over 339 days at as many as 296 sites along the Superstition Hills fault zone, and repeated measurements at 49 sites provided sufficient data to fit with a simple power law. The overall distributions of right-lateral displacement at 1 day and the estimated final slip are nearly symmetrical about the midpoint of the surface rupture. The average estimated final right-lateral slip for the Superstition Hills fault zone is ~54cm. The average left-lateral slip for the conjugate faults trending northeastward is ~23cm. The southernmost ruptured member of the Superstition Hills fault zone, newly named the Wienert fault, extends the known length of the zone by about 4km. -from Authors

The hemodynamics in intracranial aneurysm ruptured region with active contrast leakage during computed tomography angiography

NASA Astrophysics Data System (ADS)

Li, Ming-Lung; Wang, Yi-Chou; Liou, Tong-Miin; Lin, Chao-An

2014-10-01

Precise locations of rupture region under contrast agent leakage of five ruptured cerebral artery aneurysms during computed tomography angiography, which is to our knowledge for the first time, were successfully identified among 101 patients. These, together with numerical simulations based on the reconstructed aneurysmal models, were used to analyze hemodynamic parameters of aneurysms under different cardiac cyclic flow rates. For side wall type aneurysms, different inlet flow rates have mild influences on the shear stresses distributions. On the other hand, for branch type aneurysms, the predicted wall shear stress (WSS) correlates strongly with the increase of inlet vessel velocity. The mean and time averaged WSSes at rupture regions are found to be lower than those over the surface of the aneurysms. Also, the levels of the oscillatory shear index (OSI) are higher than the reported threshold value, supporting the assertion that high OSI correlates with rupture of the aneurysm. However, the present results also indicate that OSI level at the rupture region is relatively lower.

A synthetic GMPE based on deterministic simulated ground motion data obtained from dynamic rupture models

NASA Astrophysics Data System (ADS)

Dalguer, L. A.; Baumann, C.; Cauzzi, C.

2013-12-01

Empirical ground motion prediction in the very near-field and for large magnitudes is often based on extrapolation of ground motion prediction equations (GMPEs) outside the range where they are well constrained by recorded data. With empirical GMPEs it is also difficult to capture source-dominated ground motion patterns, such as the effects of velocity pulses induced by subshear and supershear rupture directivity, buried and surface-rupturing, hanging-wall and foot-wall, weak shallow layers, complex geometry faults and stress drop. A way to cope at least in part with these shortcomings is to augment the calibration datasets with synthetic ground motions. To this aim, physics-based dynamic rupture models - where the physical bases involved in the fault rupture are explicitly considered - appear to be a suitable approach to produce synthetic ground motions. In this contribution, we first perform an assessment of a database of synthetic ground motions generated by a suite of dynamic rupture simulations to verify compatibility of the peak ground amplitudes with current GMPEs. The synthetic data-set is composed by 360 earthquake scenarios with moment magnitudes in the range of 5.5-7, for three mechanisms of faulting (reverse, normal and strike-slip) and for both buried faults and surface rupturing faults. Second, we parameterise the synthetic dataset through a GMPE. For this purpose, we identify the basic functional forms by analyzing the variation of the synthetic peak ground motions and spectral ordinates as a function of different explanatory variables related to the earthquake source characteristics, in order to account for some of the source effects listed above. We argue that this study provides basic guidelines for the developments of future GMPEs including data from physics-based numerical simulations.

Ceramic Composite Intermediate Temperature Stress-Rupture Properties Improved Significantly

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurst, Janet B.

2002-01-01

Silicon carbide (SiC) composites are considered to be potential materials for future aircraft engine parts such as combustor liners. It is envisioned that on the hot side (inner surface) of the combustor liner, composites will have to withstand temperatures in excess of 1200 C for thousands of hours in oxidizing environments. This is a severe condition; however, an equally severe, if not more detrimental, condition exists on the cold side (outer surface) of the combustor liner. Here, the temperatures are expected to be on the order of 800 to 1000 C under high tensile stress because of thermal gradients and attachment of the combustor liner to the engine frame (the hot side will be under compressive stress, a less severe stress-state for ceramics). Since these composites are not oxides, they oxidize. The worst form of oxidation for strength reduction occurs at these intermediate temperatures, where the boron nitride (BN) interphase oxidizes first, which causes the formation of a glass layer that strongly bonds the fibers to the matrix. When the fibers strongly bond to the matrix or to one another, the composite loses toughness and strength and becomes brittle. To increase the intermediate temperature stress-rupture properties, researchers must modify the BN interphase. With the support of the Ultra-Efficient Engine Technology (UEET) Program, significant improvements were made as state-of-the-art SiC/SiC composites were developed during the Enabling Propulsion Materials (EPM) program. Three approaches were found to improve the intermediate-temperature stress-rupture properties: fiber-spreading, high-temperature silicon- (Si) doped boron nitride (BN), and outside-debonding BN.

Multi-Fault Rupture Scenarios in the Brawley Seismic Zone

NASA Astrophysics Data System (ADS)

Kyriakopoulos, C.; Oglesby, D. D.; Rockwell, T. K.; Meltzner, A. J.; Barall, M.

2017-12-01

Dynamic rupture complexity is strongly affected by both the geometric configuration of a network of faults and pre-stress conditions. Between those two, the geometric configuration is more likely to be anticipated prior to an event. An important factor in the unpredictability of the final rupture pattern of a group of faults is the time-dependent interaction between them. Dynamic rupture models provide a means to investigate this otherwise inscrutable processes. The Brawley Seismic Zone in Southern California is an area in which this approach might be important for inferring potential earthquake sizes and rupture patterns. Dynamic modeling can illuminate how the main faults in this area, the Southern San Andreas (SSAF) and Imperial faults, might interact with the intersecting cross faults, and how the cross faults may modulate rupture on the main faults. We perform 3D finite element modeling of potential earthquakes in this zone assuming an extended array of faults (Figure). Our results include a wide range of ruptures and fault behaviors depending on assumptions about nucleation location, geometric setup, pre-stress conditions, and locking depth. For example, in the majority of our models the cross faults do not strongly participate in the rupture process, giving the impression that they are not typically an aid or an obstacle to the rupture propagation. However, in some cases, particularly when rupture proceeds slowly on the main faults, the cross faults indeed can participate with significant slip, and can even cause rupture termination on one of the main faults. Furthermore, in a complex network of faults we should not preclude the possibility of a large event nucleating on a smaller fault (e.g. a cross fault) and eventually promoting rupture on the main structure. Recent examples include the 2010 Mw 7.1 Darfield (New Zealand) and Mw 7.2 El Mayor-Cucapah (Mexico) earthquakes, where rupture started on a smaller adjacent segment and later cascaded into a larger event. For that reason, we are investigating scenarios of a moderate rupture on a cross fault, and determining conditions under which the rupture will propagate onto the adjacent SSAF. Our investigation will provide fundamental insights that may help us interpret faulting behaviors in other areas, such as the complex Mw 7.8 2016 Kaikoura (New Zealand) earthquake.

Separated rupture and retraction of a bi-layer free film

NASA Astrophysics Data System (ADS)

Stewart, Peter; Feng, Jie; Griffiths, Ian

2017-11-01

We investigate the dynamics of a rising air bubble in an aqueous phase coated with a layer of oil. Recent experiments have shown that bubble rupture at the compound air/oil/aqueous interface can effectively disperse submicrometre oil droplets into the aqueous phase, suggesting a possible mechanism for clean-up of oil spillages on the surface of the ocean. Using a theoretical model we consider the stability of the long liquid free film formed as the bubble reaches the free surface, composed of two immiscible layers of differing viscosities, where each layer experiences a van der Waals force between its interfaces. For an excess of surfactant on one gas-liquid interface we show that the instability manifests as distinct rupture events, with the oil layer rupturing first and retracting over the in-tact water layer beneath, consistent with the experimental observations. We use our model to examine the dynamics of oil retraction, showing that it follows a power-law for short times, and examine the influence of retraction on the stability of the water layer.

Role of infrasound pressure waves in atherosclerotic plaque rupture: a theoretical approach.

PubMed

Tsatsaris, Athanasios; Koukounaris, Efstathios; Motsakos, Theodoros; Perrea, Despina

2007-01-01

To investigate the role of infrasound aortic pressure waves (IPW) in atherosclerotic plaque rupture. Atherosclerotic plaques have been simulated partly, in two dimensions, as being short or long Conical Intersections (CIS), that is to say elliptic, parabolic or hyperbolic surfaces. Consequently, the course and reflection of the generated aortic pressure wave (infrasound domain-less than 20Hz) has been examined around the simulated plaques. The incidence of IPW on plaque surface results both in reflection and "refraction" of the wave. The IPW course within tissue, seems to be enhanced by high Cu-level presence at these areas according to recent evidence (US2003000388213). The "refracted", derived wave travels through plaque tissue and is eventually accumulated to the foci of the respective CIS-plaque geometry. The foci location within or underneath atheroma declares zones where infrasound energy is mostly absorbed. This process, among other mechanisms may contribute to plaque rupture through the development of local hemorrhage and inflammation in foci areas. In future, detection of foci areas and repair (i.e. via Laser Healing Microtechnique) may attenuate atherosclerotic plaque rupture behavior.

Surface Rupture Effects on Earthquake Moment-Area Scaling Relations

NASA Astrophysics Data System (ADS)

Luo, Yingdi; Ampuero, Jean-Paul; Miyakoshi, Ken; Irikura, Kojiro

2017-09-01

Empirical earthquake scaling relations play a central role in fundamental studies of earthquake physics and in current practice of earthquake hazard assessment, and are being refined by advances in earthquake source analysis. A scaling relation between seismic moment ( M 0) and rupture area ( A) currently in use for ground motion prediction in Japan features a transition regime of the form M 0- A 2, between the well-recognized small (self-similar) and very large (W-model) earthquake regimes, which has counter-intuitive attributes and uncertain theoretical underpinnings. Here, we investigate the mechanical origin of this transition regime via earthquake cycle simulations, analytical dislocation models and numerical crack models on strike-slip faults. We find that, even if stress drop is assumed constant, the properties of the transition regime are controlled by surface rupture effects, comprising an effective rupture elongation along-dip due to a mirror effect and systematic changes of the shape factor relating slip to stress drop. Based on this physical insight, we propose a simplified formula to account for these effects in M 0- A scaling relations for strike-slip earthquakes.

Toward tsunami early warning system in Indonesia by using rapid rupture durations estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madlazim

2012-06-20

Indonesia has Indonesian Tsunami Early Warning System (Ina-TEWS) since 2008. The Ina-TEWS has used automatic processing on hypocenter; Mwp, Mw (mB) and Mj. If earthquake occurred in Ocean, depth < 70 km and magnitude > 7, then Ina-TEWS announce early warning that the earthquake can generate tsunami. However, the announcement of the Ina-TEWS is still not accuracy. Purposes of this research are to estimate earthquake rupture duration of large Indonesia earthquakes that occurred in Indian Ocean, Java, Timor sea, Banda sea, Arafura sea and Pasific ocean. We analyzed at least 330 vertical seismogram recorded by IRIS-DMC network using a directmore » procedure for rapid assessment of earthquake tsunami potential using simple measures on P-wave vertical seismograms on the velocity records, and the likelihood that the high-frequency, apparent rupture duration, T{sub dur}. T{sub dur} can be related to the critical parameters rupture length (L), depth (z), and shear modulus ({mu}) while T{sub dur} may be related to wide (W), slip (D), z or {mu}. Our analysis shows that the rupture duration has a stronger influence to generate tsunami than Mw and depth. The rupture duration gives more information on tsunami impact, Mo/{mu}, depth and size than Mw and other currently used discriminants. We show more information which known from the rupture durations. The longer rupture duration, the shallower source of the earthquake. For rupture duration greater than 50 s, the depth less than 50 km, Mw greater than 7, the longer rupture length, because T{sub dur} is proportional L and greater Mo/{mu}. Because Mo/{mu} is proportional L. So, with rupture duration information can be known information of the four parameters. We also suggest that tsunami potential is not directly related to the faulting type of source and for events that have rupture duration greater than 50 s, the earthquakes generated tsunami. With available real-time seismogram data, rapid calculation, rupture duration discriminant can be completed within 4-5 min after an earthquake occurs and thus can aid in effective, accuracy and reliable tsunami early warning for Indonesia region.« less

Engineering a nanostructured "super surface" with superhydrophobic and superkilling properties.

PubMed

Hasan, Jafar; Raj, Shammy; Yadav, Lavendra; Chatterjee, Kaushik

2015-05-12

We present a nanostructured "super surface" fabricated using a simple recipe based on deep reactive ion etching of a silicon wafer. The topography of the surface is inspired by the surface topographical features of dragonfly wings. The super surface is comprised of nanopillars 4 μm in height and 220 nm in diameter with random inter-pillar spacing. The surface exhibited superhydrophobicity with a static water contact angle of 154.0° and contact angle hysteresis of 8.3°. Bacterial studies revealed the bactericidal property of the surface against both gram negative ( Escherichia coli ) and gram positive ( Staphylococcus aureus ) strains through mechanical rupture of the cells by the sharp nanopillars. The cell viability on these nanostructured surfaces was nearly six-fold lower than on the unmodified silicon wafer. The nanostructured surface also killed mammalian cells (mouse osteoblasts) through mechanical rupture of the cell membrane. Thus, such nanostructured super surfaces could find applications for designing self-cleaning and anti-bacterial surfaces in diverse applications such as microfluidics, surgical instruments, pipelines and food packaging.

Dynamics of delayed triggering in multi-segmented foreshock sequence: Evidence from the 2016 Kumamoto, Japan, earthquake

NASA Astrophysics Data System (ADS)

Arai, H.; Ando, R.; Aoki, Y.

2017-12-01

The 2016 Kumamoto earthquake sequence hit the SW Japan, from April 14th to 16th and its sequence includes two M6-class foreshocks and the main shock (Mw 7.0). Importantly, the detailed surface displacement caused solely by the two foreshocks could be captured by a SAR observation isolated from the mainshock deformation. The foreshocks ruptured the previously mapped Hinagu fault and their hypocentral locations and the aftershock distribution indicates the involvement of two different subparallel faults. Therefore we assumed that the 1st and the 2nd foreshocks respectively ruptured each of the subparallel faults (faults A and B). One of the interesting points of this earthquake is that the two major foreshocks had a temporal gap of 2.5 hours even though the fault A and B are quite close by each other. This suggests that the stress perturbation due to the 1st foreshock is not large enough to trigger the 2nd one right away but that it's large enough to bring about the following earthquake after a delay time.We aim to reproduce the foreshock sequence such as rupture jumping over the subparallel faults by using dynamic rupture simulations. We employed a spatiotemporal-boundary integral equation method accelerated by the Fast Domain Partitioning Method (Ando, 2016, GJI) since this method allows us to construct a complex fault geometry in 3D media. Our model has two faults and a free ground surface. We conducted rupture simulation with various sets of parameters to identify the optimal condition describing the observation.Our simulation results are roughly categorized into 3 cases with regard to the criticality for the rupture jumping. The case 1 (supercritical case) shows the fault A and B ruptured consecutively without any temporal gap. In the case 2 (nearly critical), the rupture on the fault B started with a temporal gap after the fault A finished rupturing, which is what we expected as a reproduction. In the case 3 (subcritical), only the fault A ruptured and its rupture did not transfer to the fault B. We succeed in reproducing rupture jumping over two faults with a temporal gap due to the nucleation by taking account of a velocity strengthening (direct) effect. With a detailed analysis of the case 2, we can constrain ranges of parameters strictly, and this gives us deeper insights into the physics underlying the delayed foreshock activity.

Modeling earthquake sequences along the Manila subduction zone: Effects of three-dimensional fault geometry

NASA Astrophysics Data System (ADS)

Yu, Hongyu; Liu, Yajing; Yang, Hongfeng; Ning, Jieyuan

2018-05-01

To assess the potential of catastrophic megathrust earthquakes (MW > 8) along the Manila Trench, the eastern boundary of the South China Sea, we incorporate a 3D non-planar fault geometry in the framework of rate-state friction to simulate earthquake rupture sequences along the fault segment between 15°N-19°N of northern Luzon. Our simulation results demonstrate that the first-order fault geometry heterogeneity, the transitional-segment (possibly related to the subducting Scarborough seamount chain) connecting the steeper south segment and the flatter north segment, controls earthquake rupture behaviors. The strong along-strike curvature at the transitional-segment typically leads to partial ruptures of MW 8.3 and MW 7.8 along the southern and northern segments respectively. The entire fault occasionally ruptures in MW 8.8 events when the cumulative stress in the transitional-segment is sufficiently high to overcome the geometrical inhibition. Fault shear stress evolution, represented by the S-ratio, is clearly modulated by the width of seismogenic zone (W). At a constant plate convergence rate, a larger W indicates on average lower interseismic stress loading rate and longer rupture recurrence period, and could slow down or sometimes stop ruptures that initiated from a narrower portion. Moreover, the modeled interseismic slip rate before whole-fault rupture events is comparable with the coupling state that was inferred from the interplate seismicity distribution, suggesting the Manila trench could potentially rupture in a M8+ earthquake.

Overestimation of the earthquake hazard along the Himalaya: constraints in bracketing of medieval earthquakes from paleoseismic studies

NASA Astrophysics Data System (ADS)

Arora, Shreya; Malik, Javed N.

2017-12-01

The Himalaya is one of the most seismically active regions of the world. The occurrence of several large magnitude earthquakes viz. 1905 Kangra earthquake (Mw 7.8), 1934 Bihar-Nepal earthquake (Mw 8.2), 1950 Assam earthquake (Mw 8.4), 2005 Kashmir (Mw 7.6), and 2015 Gorkha (Mw 7.8) are the testimony to ongoing tectonic activity. In the last few decades, tremendous efforts have been made along the Himalayan arc to understand the patterns of earthquake occurrences, size, extent, and return periods. Some of the large magnitude earthquakes produced surface rupture, while some remained blind. Furthermore, due to the incompleteness of the earthquake catalogue, a very few events can be correlated with medieval earthquakes. Based on the existing paleoseismic data certainly, there exists a complexity to precisely determine the extent of surface rupture of these earthquakes and also for those events, which occurred during historic times. In this paper, we have compiled the paleo-seismological data and recalibrated the radiocarbon ages from the trenches excavated by previous workers along the entire Himalaya and compared earthquake scenario with the past. Our studies suggest that there were multiple earthquake events with overlapping surface ruptures in small patches with an average rupture length of 300 km limiting Mw 7.8-8.0 for the Himalayan arc, rather than two or three giant earthquakes rupturing the whole front. It has been identified that the large magnitude Himalayan earthquakes, such as 1905 Kangra, 1934 Bihar-Nepal, and 1950 Assam, that have occurred within a time frame of 45 years. Now, if these events are dated, there is a high possibility that within the range of ±50 years, they may be considered as the remnant of one giant earthquake rupturing the entire Himalayan arc. Therefore, leading to an overestimation of seismic hazard scenario in Himalaya.

Mineralogical compositions of fault rocks from surface ruptures of Wenchuan earthquake and implication of mineral transformation during the seismic cycle along Yingxiu-Beichuan fault, Sichuan Province, China

NASA Astrophysics Data System (ADS)

Dang, Jiaxiang; Zhou, Yongsheng; He, Changrong; Ma, Shengli

2018-06-01

There are two co-seismic bedrock surface ruptures from the Mw 7.9 Wenchuan earthquake in the northern and central parts of the Beichuan-Yingxiu fault, Sichuan Province, southwest China. In this study, we report on the macrostructure of the fault rocks and results from X-ray powder diffraction analysis of minerals from rocks in the fault zone. The most recent fault gouge (the gouge produced by the most recent co-seismic fault movement) in all the studied outcrops is dark or grayish-black, totally unconsolidated and ultrafine-grained. Older fault gouges in the same outcrops are grayish or yellowish and weakly consolidated. X-ray powder diffraction analysis results show that mineral assemblages in both the old fault gouge and the new fault gouge are more complicated than the mineral assemblages in the bedrock as the fault gouge is rich in clay minerals. The fault gouge inherited its major rock-forming minerals from the parent rocks, but the clay minerals in the fault gouge were generated in the fault zone and are therefore authigenic and synkinematic. In profiles across the fault, clay mineral abundances increase as one traverses from the bedrock to the breccia to the old gouge and from the old gouge to the new gouge. Quartz and illite are found in all collected gouge samples. The dominant clay minerals in the new fault gouge are illite and smectite along the northern part of the surface rupture and illite/smectite mixed-layer clay in the middle part of the rupture. Illite/smectite mixed-layer clay found in the middle part of the rupture indicates that fault slip was accompanied by K-rich fluid circulation. The existence of siderite, anhydrite, and barite in the northern part of the rupture suggests that fault slip at this locality was accompanied by acidic fluids containing ions of Fe, Ca, and Ba.

Global surface displacement data for assessing variability of displacement at a point on a fault

USGS Publications Warehouse

Hecker, Suzanne; Sickler, Robert; Feigelson, Leah; Abrahamson, Norman; Hassett, Will; Rosa, Carla; Sanquini, Ann

2014-01-01

This report presents a global dataset of site-specific surface-displacement data on faults. We have compiled estimates of successive displacements attributed to individual earthquakes, mainly paleoearthquakes, at sites where two or more events have been documented, as a basis for analyzing inter-event variability in surface displacement on continental faults. An earlier version of this composite dataset was used in a recent study relating the variability of surface displacement at a point to the magnitude-frequency distribution of earthquakes on faults, and to hazard from fault rupture (Hecker and others, 2013). The purpose of this follow-on report is to provide potential data users with an updated comprehensive dataset, largely complete through 2010 for studies in English-language publications, as well as in some unpublished reports and abstract volumes.

Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT)

DTIC Science & Technology

2012-08-01

unlimited 3.1.2. Fractography Figure 5: SEM images of a 3.18mm thick sheet specimen tested at 760◦C/758MPa. (a) The region near the fracture surface... fractography using secondary electron imaging (SE) in a scanning electron microscope (SEM). No surface oxidation was observed at this temperature. The...ruptured after 210 hours. 3.2.3. Fractography The SEM image of the reconstructed creep ruptured specimen with thickness h = 3.18mm is shown in Fig. 18a

Dynamic Rupture and Energy Partition in Models of Earthquake Faults

NASA Astrophysics Data System (ADS)

Shi, Z.; Needleman, A.; Ben-Zion, Y.

2006-12-01

We study properties of dynamic rupture and the partition of energy between radiation and dissipative mechanisms using 2D finite element calculations. The goal is to improve the understanding of these processes on faults at different evolutionary stages associated with different levels of geometrical complexity and possible presence of contrasting elastic properties across the fault. The initial calculations employ homogeneous media and a planar internal interface governed by a general rate- and state-dependent friction law that accounts for the gradual response of shear stress to abrupt changes of normal stress. Ruptures are initiated by gradually increasing the shear traction in a limited nucleation zone near the origin. By changing the rate dependency of the friction law and the size of the nucleation zone, we obtain four rupture modes: (i) supershear crack-like rupture; (ii) subshear crack-like rupture; (iii) subshear single pulse; and (iv) supershear train of pulses. Increasing the initial shear stress produces a transition from a subshear crack to a supershear crack, while increasing the rate dependency of the friction produces self-healing and the transition from a crack-like to a pulse mode of rupture. Properties of the nucleation process can strongly affect the rupture mode. In the cases examined, the total release of strain energy (over the same propagation distance) decreases following the order: supershear crack, subshear crack, train of pulses and single pulse. The ratio of the radiated kinetic energy to the energy dissipated in friction is about 5% for the supershear crack case and about 2% for the other three cases. Future work will involve similar calculations accounting for the generation of plastic strain in the bulk, the material contrast across the fault, and the addition of cohesive surfaces in the bulk to allow for the generation of new surfaces. The study may provide fundamental information on rupture processes in geologically-relevant circumstances and improve the understanding of physical limits on extreme ground motion. The results may be used to check assumptions made in observational works and may help to guide new observational research.

Processing of microencapsulated dyes for the visual inspection of fibre reinforced plastics

NASA Astrophysics Data System (ADS)

Hopmann, Ch.; Kerschbaum, M.; Küsters, K.

2014-05-01

The evaluation of damages caused during processing, assembly or usage of fibre reinforced plastics is still a challenge. The use of inspection technology like ultrasonic scanning enables a detailed damage analysis but requires high investments and trained staff. Therefore, the visual inspection method is widely used. A drawback of this method is the difficult identification of barely visible damages, which can already be detrimental for the structural integrity. Therefore an approach is undertaken to integrate microencapsulated dyes into the laminates of fibre reinforced plastic parts to highlight damages on the surface. In case of a damage, the microcapsules rupture which leads to a release of the dye and a visible bruise on the part surface. To enable a wide application spectrum for this technology the microcapsules must be processable without rupturing with established manufacturing processes for fibre reinforced plastics. Therefore the incorporation of microcapsules in the filament winding, prepreg autoclave and resin transfer moulding (RTM) process is investigated. The results show that the use of a carrier medium is a feasible way to incorporate the microcapsules into the laminate for all investigated manufacturing processes. Impact testing of these laminates shows a bruise formation on the specimen surface which correlates with the impact energy level. This indicates a microcapsule survival during processing and shows the potential of this technology for damage detection and characterization.

Mapping of the surface rupture induced by the M 7.3 Kumamoto Earthquake along the Eastern segment of Futagawa fault using image correlation techniques

NASA Astrophysics Data System (ADS)

Ekhtari, N.; Glennie, C. L.; Fielding, E. J.; Liang, C.

2016-12-01

Near field surface deformation is vital to understanding the shallow fault physics of earthquakes but near-field deformation measurements are often sparse or not reliable. In this study, we use the Co-seismic Image Correlation (COSI-Corr) technique to map the near-field surface deformation caused by the M 7.3 April 16, 2016 Kumamoto Earthquake, Kyushu, Japan. The surface rupture around the Eastern segment of Futagawa fault is mapped using a pair of panchromatic 1.5 meter resolution SPOT 7 images. These images were acquired on January 16 and April 29, 2016 (3 months before and 13 days after the earthquake respectively) with close to nadir (less than 1.5 degree off nadir) viewing angle. The two images are ortho-rectified using SRTM Digital Elevation Model and further co-registered using tie points far away from the rupture field. Then the COSI-Corr technique is utilized to produce an estimated surface displacement map, and a horizontal displacement vector field is calculated which supplies a seamless estimate of near field displacement measurements along the Eastern segment of the Futagawa fault. The COSI-Corr estimated displacements are then compared to other existing displacement observations from InSAR, GPS and field observations.

Shake, Rupture And Flow: Hydraulic Constraints On The Formation Of Europa’s Chaos

NASA Astrophysics Data System (ADS)

Schmidt, Britney E.; Gooch, B. T.; Blankenship, D. D.; Soderlund, K. M.

2012-10-01

Europa’s chaos terrains may have formed above shallow water lenses formed by melting of the upper ice shell with ascending thermo-compositional plumes. A key factor in the creation of chaos terrain may be dramatic disruption and collapse of the ice lid above the forming melt lens along with potentially violent mixing upon its rupture; this is analogous to the collapse of terrestrial ice shelves in which massive ice bodies disintegrate in a few days. At Thera Macula, there is evidence for modification by water immediately external to the scarp that bounds the collapsed region. Since water runs either subaerially down hill or from high pressure to low when below or within ice, the swollen appearance of bands entering Thera Macula, which are uphill in terms of hydraulic and topographic gradients, raises the possibility that this steep scarp represents the place where the lens initially broke. As the ice lid ruptures, the overpressure within the lens may create sufficient pressure within the fracture to drive water through it, allowing water to escape into and modify surrounding terrain. Similar effects are seen when aquifers or subglacial water sources are tapped: water flows up the pipe until the pressure in the water body is relieved and the hydraulic “pressure head” in the pipe is lowered. We have modeled the hydraulic potential associated with a rupturing lens in order to investigate the range of parameters for overpressure, fracture width, and lid thickness that could produce such modification as is observed at Thera Macula. These place important constraints on the pressure within the lens and the energetics of a collapse event. These estimates may explain how ice masses within chaos are initially disrupted and provide a means for quantifying the vigor of surface-subsurface mixing that could be critical to Europa’s habitability.

Rupture of thin liquid films on structured surfaces

NASA Astrophysics Data System (ADS)

Ajaev, Vladimir S.; Gatapova, Elizaveta Ya.; Kabov, Oleg A.

2011-10-01

We investigate stability and breakup of a thin liquid film on a solid surface under the action of disjoining pressure. The solid surface is structured by parallel grooves. Air is trapped in the grooves under the liquid film. Our mathematical model takes into account the effect of slip due to the presence of menisci separating the liquid film from the air inside the grooves, the deformation of these menisci due to local variations of pressure in the liquid film, and nonuniformities of the Hamaker constant which measures the strength of disjoining pressure. Both linear stability and strongly nonlinear evolution of the film are analyzed. Surface structuring results in decrease of the fastest growing instability wavelength and the rupture time. It is shown that a simplified description of film dynamics based on the standard formula for effective slip leads to significant deviations from the behavior seen in our simulations. Self-similar decay over several orders of magnitude of the film thickness near the rupture point is observed. We also show that the presence of the grooves can lead to instability in otherwise stable films if the relative groove width is above a critical value, found as a function of disjoining pressure parameters.

Timing of late Holocene surface rupture of the Wairau Fault, Marlborough, New Zealand

USGS Publications Warehouse

Zachariasen, J.; Berryman, K.; Langridge, Rob; Prentice, C.; Rymer, M.; Stirling, M.; Villamor, P.

2006-01-01

Three trenches excavated across the central portion of the right-lateral strike-slip Wairau Fault in South Island, New Zealand, exposed a complex set of fault strands that have displaced a sequence of late Holocene alluvial and colluvial deposits. Abundant charcoal fragments provide age control for various stratigraphic horizons dating back to c. 5610 yr ago. Faulting relations from the Wadsworth trench show that the most recent surface rupture event occurred at least 1290 yr and at most 2740 yr ago. Drowned trees in landslide-dammed Lake Chalice, in combination with charcoal from the base of an unfaulted colluvial wedge at Wadsworth trench, suggest a narrower time bracket for this event of 1811-2301 cal. yr BP. The penultimate faulting event occurred between c. 2370 and 3380 yr, and possibly near 2680 ?? 60 cal. yr BP, when data from both the Wadsworth and Dillon trenches are combined. Two older events have been recognised from Dillon trench but remain poorly dated. A probable elapsed time of at least 1811 yr since the last surface rupture, and an average slip rate estimate for the Wairau Fault of 3-5 mm/yr, suggests that at least 5.4 m and up to 11.5 m of elastic shear strain has accumulated since the last rupture. This is near to or greater than the single-event displacement estimates of 5-7 m. The average recurrence interval for surface rupture of the fault determined from the trench data is 1150-1400 yr. Although the uncertainties in the timing of faulting events and variability in inter-event times remain high, the time elapsed since the last event is in the order of 1-2 times the average recurrence interval, implying that the Wairau Fault is near the end of its interseismic period. ?? The Royal Society of New Zealand 2006.

Near-Fault Strong Ground Motions during the 2016 Kumamoto, Japan, Earthquake

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.

2016-12-01

The 2016 Kumamoto mainshock (Mw7.0) produced a surface ruptured fault of about 20km long with maximum 2m offset, and identified as a surface ruptured event. Two strong motion records were observed near the surface ruptured fault at Mashiki town hall and Nishihara village hall. We investigated characteristics of those strong ground motions. As the acceleration records consisted of the baseline errors caused by nonzero initial acceleration and tilting of the accelerograph, we carefully removed the baseline errors (c.f. Chiu, 2001, Boore and Bommer, 2005) so as to obtain velocity and displacements. The observed permanent displacements were about 1.2m in horizontal direction and about 0.7m sinking in vertical direction at Mashiki town hall, and about 1.7m and 1.8m, respectively, at Nishihara village hall. Those permanent displacements almost coincide to results by GNSS and InSAR analysis (e.g., GSI, 2016). It takes about only 3 s to reach the permanent displacement. Somerville (2003) pointed out that ground motions from earthquakes producing large surface ruptures appeared to have systematically weaker ground motions than ground motions from earthquakes whose rupture were confined to the subsurface using the Ground Motion Prediction Equation (GMPE) for response spectra (Abrahamson and Silva, 1997). We calculated the response spectra of those records, compared them to the GMPE with the same manner and found two records were systematically larger than the expected from the GMPE in the period range of 0.3 s to 5 s. We need to re-consider the working hypothesis that the near-fault ground motions are weaker and to separate the near-fault and site effects on ground motions. Strong motions in the longer period range would be mainly caused by the near-fault (near-field term) effect.We used the acceleration data of the Kumamoto seismic intensity information network, provided by JMA.

Formation of a cavitation cluster in the vicinity of a quasi-empty rupture

NASA Astrophysics Data System (ADS)

Bol'shakova, E. S.; Kedrinskiy, V. K.

2017-09-01

The presentation deals with one of the experimental and numerical models of a quasi-empty rupture in the magma melt. This rupture is formed in the liquid layer of a distilled cavitating fluid under shock loading within the framework of the problem formulation with a small electromagnetic hydrodynamic shock tube. It is demonstrated that the rupture is shaped as a spherical segment, which retains its topology during the entire process of its evolution and collapsing. The dynamic behavior of the quasi-empty rupture is analyzed, and the growth of cavitating nuclei in the form of the boundary layer near the entire rupture interface is found. It is shown that rupture implosion is accompanied by the transformation of the bubble boundary layer to a cavitating cluster, which takes the form of a ring-shaped vortex floating upward to the free surface of the liquid layer. A p-κ mathematical model is formulated, and calculations are performed to investigate the implosion of a quasi-empty spherical cavity in the cavitating liquid, generation of a shock wave by this cavity, and dynamics of the bubble density growth in the cavitating cluster by five orders of magnitude.

Influence of Melt Superheating Treatment on Solidification Characteristics and Rupture Life of a Third-Generation Ni-Based Single-Crystal Superalloy

NASA Astrophysics Data System (ADS)

Su, Haijun; Wang, Haifeng; Zhang, Jun; Guo, Min; Liu, Lin; Fu, Hengzhi

2018-05-01

The influence of melt superheating treatment on the melt properties, solidification characteristics, and rupture life of a third-generation Ni-based single-crystal superalloy was investigated to reveal the critical temperature range of melt structure evolution and its effect on rupture life. The results showed that the viscosity of superalloy decreased but the surface tension increased with increasing superheating temperature. Two characteristic temperature points where the melt viscosity and undercooling degree suddenly change were determined to be 1600 °C and 1700 °C, respectively. Similarly, the stability of the solidification interface firstly improved and then weakened with increasing superheating temperature. The dendrite arms were well refined and the segregation was reduced at 1700 °C. In addition, the rupture life obtained at 1100 °C and 137 MPa increased by approximately 30 pct, approaching the rupture life of the corresponding superalloy containing 2 pct Ru, with increasing superheating temperature from 1500 °C to 1700 °C. When the melt was further heated to 1800 °C, the rupture life decreased. The evolutions of solidification characteristics and rupture life with increasing melt superheating temperature were attributed to changes in the melt structure.

The Kumamoto Mw7.1 mainshock: deep initiation triggered by the shallow foreshocks

NASA Astrophysics Data System (ADS)

Shi, Q.; Wei, S.

2017-12-01

The Kumamoto Mw7.1 earthquake and its Mw6.2 foreshock struck the central Kyushu region in mid-April, 2016. The surface ruptures are characterized with multiple fault segments and a mix of strike-slip and normal motion extended from the intersection area of Hinagu and Futagawa faults to the southwest of Mt. Aso. Despite complex surface ruptures, most of the finite fault inversions use two fault segments to approximate the fault geometry. To study the rupture process and the complex fault geometry of this earthquake, we performed a multiple point source inversion for the mainshock using the data on 93 K-net and Kik-net stations. With path calibration from the Mw6.0 foreshock, we selected the frequency ranges for the Pnl waves (0.02 0.26 Hz) and surface waves (0.02 0.12 Hz), as well as the components that can be well modeled with the 1D velocity model. Our four-point-source results reveal a unilateral rupture towards Mt. Aso and varying fault geometries. The first sub-event is a high angle ( 79°) right-lateral strike-slip event at the depth of 16 km on the north end of the Hinagu fault. Notably the two M>6 foreshocks is located by our previous studies near the north end of the Hinagu fault at the depth of 5 9 km, which may give rise to the stress concentration at depth. The following three sub-events are distributed along the surface rupture of the Futagawa fault, with focal depths within 4 10 km. Their focal mechanisms present similar right-lateral fault slips with relatively small dip angles (62 67°) and apparent normal-fault component. Thus, the mainshock rupture initiated from the relatively deep part of the Hinagu fault and propagated through the fault-bend toward NE along the relatively shallow part of the Futagawa fault until it was terminated near Mt. Aso. Based on the four-point-source solution, we conducted a finite-fault inversion and obtained a kinematic rupture model of the mainshock. We then performed the Coulomb Stress analyses on the two foreshocks and the mainshock. The results support that the stress alternation after the foreshocks may have triggered the failure on the fault plane of the Mw7.1 earthquake. Therefore, the 2016 Kumamoto earthquake sequence is dominated by a series of large triggering events whose initiation is associated with the geometric barrier in the intersection of the Futagawa and Hinagu faults.

Correlation of Coseismic Velocity and Static Volumetric Strain Changes Induced by the 2010 Mw6.3 Jiasian Earthquake under the Southern Taiwan Orogenic Belt

NASA Astrophysics Data System (ADS)

Wu, S. M.; Hung, S. H.

2015-12-01

Earthquake-induced temporal changes in seismic velocity of the earth's crust have been demonstrated to be monitored effectively by the time-lapse shifts of coda waves recently. Velocity drop during the coseismic rupture has been explicitly observed in proximity to the epicenters of large earthquakes with different styles of faulting. The origin of such sudden perturbation in crustal properties is closely related to the damage and/or volumetric strain change influenced by seismic slip distribution. In this study, we apply a coda wave interferometry method to investigate potential velocity change in both space and time related to the moderate-sized (Mw6.3) 2010 Jiasian earthquake, which nucleated deeply in the crust (~23 km), ruptured and terminated around the depth of 10 km along a previously unidentified blind thrust fault near the lithotectonic boundary of the southern Taiwan orogenic belt. To decipher the surface and crustal response to this relatively deep rupture, we first measure relative time-lapse changes of coda between different short-term time frames spanning one year covering the pre- and post-seismic stages by using the Moving Window Cross Spectral Method. Rather than determining temporal velocity variations based on a long-term reference stack, we conduct a Bayesian least-squares inversion to obtain the optimal estimates by minimizing the inconsistency between the relative time-lapse shifts of individual short-term stacks. The results show the statistically significant velocity reduction immediately after the mainshock, which is most pronounced at the pairs with the interstation paths traversing through the hanging-wall block of the ruptured fault. The sensitivity of surface wave coda arrivals mainly in the periods of 3-5 s to shear wave speed perturbation is confined within the depth of 10 km, where the crust mostly experienced extensional strain changes induced by the slip distribution from the finite-fault model. Compared with coseismic slip distribution from GPS data and finite-fault inversion, peak ground velocity, and static volumetric strain field following the earthquake, the velocity decrease observed in the hanging wall side of the shallow crust is most likely attributed to pervasive dilatational strain changes induced by the slip rupture on the underlying blind thrust.

QCM operating in threshold mode as a gas sensor.

PubMed

Dultsev, Fedor N; Kolosovsky, Eugeny A

2009-10-20

Application of the threshold mode allowed us to use the quartz resonator (quartz crystal microbalance, QCM) as a highly sensitive gas sensor measuring the forces of the rupture of adsorbed gas components from the resonator surface oscillating with increasing amplitude. This procedure allows one to analyze different gas components using the same surface modification, just varying the rupture threshold by varying the amplitude of shear oscillations. The sensitivity of the threshold measurements is 2 to 3 orders of magnitude higher than for the gravimetric procedure. It is demonstrated that the QCM operating as an active element can be used as a gas sensor. This procedure seems to be promising in investigating the reactivity of the surface or the interactions of gaseous components with the surface containing various functional groups, thus contributing to the surface chemistry.

Width of the Surface Rupture Zone for Thrust Earthquakes and Implications for Earthquake Fault Zoning: Chi-Chi 1999 and Wenchuan 2008 Earthquakes

NASA Astrophysics Data System (ADS)

Boncio, P.; Caldarella, M.

2016-12-01

We analyze the zones of coseismic surface faulting along thrust faults, whit the aim of defining the most appropriate criteria for zoning the Surface Fault Rupture Hazard (SFRH) along thrust faults. Normal and strike-slip faults were deeply studied in the past, while thrust faults were not studied with comparable attention. We analyze the 1999 Chi-Chi, Taiwan (Mw 7.6) and 2008 Wenchuan, China (Mw 7.9) earthquakes. Several different types of coseismic fault scarps characterize the two earthquakes, depending on the topography, fault geometry and near-surface materials. For both the earthquakes, we collected from the literature, or measured in GIS-georeferenced published maps, data about the Width of the coseismic Rupture Zone (WRZ). The frequency distribution of WRZ compared to the trace of the main fault shows that the surface ruptures occur mainly on and near the main fault. Ruptures located away from the main fault occur mainly in the hanging wall. Where structural complexities are present (e.g., sharp bends, step-overs), WRZ is wider then for simple fault traces. We also fitted the distribution of the WRZ dataset with probability density functions, in order to define a criterion to remove outliers (e.g., by selecting 90% or 95% probability) and define the zone where the probability of SFRH is the highest. This might help in sizing the zones of SFRH during seismic microzonation (SM) mapping. In order to shape zones of SFRH, a very detailed earthquake geologic study of the fault is necessary. In the absence of such a very detailed study, during basic (First level) SM mapping, a width of 350-400 m seems to be recommended (95% of probability). If the fault is carefully mapped (higher level SM), one must consider that the highest SFRH is concentrated in a narrow zone, 50 m-wide, that should be considered as a "fault-avoidance (or setback) zone". These fault zones should be asymmetric. The ratio of footwall to hanging wall (FW:HW) calculated here ranges from 1:5 to 1:3.

Geometry, slip distribution, and kinematics of surface rupture on the Sakarya fault segment during the 17 August 1999 İzmit, Turkey, earthquake

USGS Publications Warehouse

Langridge, R.M.; Stenner, Heidi D.; Fumal, T.E.; Christofferson, S.A.; Rockwell, T.K.; Hartleb, R.D.; Bachhuber, J.; Barka, A.A.

2002-01-01

The Mw 7.4 17 August 1999 İzmit earthquake ruptured five major fault segments of the dextral North Anatolian Fault Zone. The 26-km-long, N86°W-trending Sakarya fault segment (SFS) extends from the Sapanca releasing step-over in the west to near the town of Akyazi in the east. The SFS emerges from Lake Sapanca as two distinct fault traces that rejoin to traverse the Adapazari Plain to Akyazi. Offsets were measured across 88 cultural and natural features that cross the fault, such as roads, cornfield rows, rows of trees, walls, rails, field margins, ditches, vehicle ruts, a dike, and ground cracks. The maximum displacement observed for the İzmit earthquake (∼5.1 m) was encountered on this segment. Dextral displacement for the SFS rises from less than 1 m at Lake Sapanca to greater than 5 m near Arifiye, only 3 km away. Average slip decreases uniformly to the east from Arifiye until the fault steps left from Sagir to Kazanci to the N75°W, 6-km-long Akyazi strand, where slip drops to less than 1 m. The Akyazi strand passes eastward into the Akyazi Bend, which consists of a high-angle bend (18°-29°) between the Sakarya and Karadere fault segments, a 6-km gap in surface rupture, and high aftershock energy release. Complex structural geometries exist between the İzmit, Düzce, and 1967 Mudurnu fault segments that have arrested surface ruptures on timescales ranging from 30 sec to 88 days to 32 yr. The largest of these step-overs may have acted as a rupture segmentation boundary in previous earthquake cycles.

The surface rupture and slip distribution of the 17 August 1999 Izmit earthquake (M 7.4), North Anatolian fault

USGS Publications Warehouse

Barka, A.; Akyuz, H.S.; Altunel, E.; Sunal, G.; Cakir, Z.; Dikbas, A.; Yerli, B.; Armijo, R.; Meyer, B.; De Chabalier, J. B.; Rockwell, Thomas; Dolan, J.R.; Hartleb, R.; Dawson, Tim; Christofferson, S.; Tucker, A.; Fumal, T.; Langridge, Rob; Stenner, H.; Lettis, William; Bachhuber, J.; Page, W.

2002-01-01

The 17 August 1999 İzmit earthquake occurred on the northern strand of the North Anatolian fault zone. The earthquake is associated with a 145-km-long surface rupture that extends from southwest of Düzce in the east to west of Hersek delta in the west. Detailed mapping of the surface rupture shows that it consists of five segments separated by releasing step-overs; herein named the Hersek, Karamürsel-Gölcük, İzmit-Sapanca Lake, Sapanca-Akyazi, and Karadere segments from west to east, respectively. The Hersek segment, which cuts the tip of a large delta plain in the western end of the rupture zone, has an orientation of N80°. The N70°-80°E-trending Karamürsel-Gölcük segment extends along the linear southern coasts of the İzmit Gulf between Karamürsel and Gölcük and produced the 470-cm maximum displacement in Gölcük. The northwest-southeast-striking Gölcük normal fault between the Karamürsel-Gölcük and İzmit-Sapanca segments has 2.3-m maximum vertical displacement. The maximum dextral offset along the İzmit-Sapanca Lake segment was measured to be about 3.5 m, and its trend varies between N80°E and east-west. The Sapanca-Akyazi segment trends N75°-85°W and expresses a maximum displacement of 5.2 m. The Karadere segment trends N65°E and produced up to 1.5-m maximum displacement. The Karadere and Sapanca-Akyazi segments form fan-shape or splaying ruptures near their eastern ends where the displacement also diminished.

Modeling Earthquake Rupture and Corresponding Tsunamis Along a Segment of the Alaskan-Aleutian Megathrust

NASA Astrophysics Data System (ADS)

Ryan, K. J.; Geist, E. L.; Oglesby, D. D.; Kyriakopoulos, C.

2016-12-01

Motivated by the 2011 Mw 9 Tohoku-Oki event, we explore the effects of realistic fault dynamics on slip, free surface deformation, and the resulting tsunami generation and local propagation from a hypothetical Mw 9 megathrust earthquake along the Alaskan-Aleutian (A-A) Megathrust. We demonstrate three scenarios: a spatially-homogenous prestress and frictional parameter model and two models with rate-strengthening-like friction (e.g., Dieterich, 1992). We use a dynamic finite element code to model 3-D ruptures, using time-weakening friction (Andrews, 2004) as a proxy for rate-strengthening friction, along a portion of the A-A subduction zone. Given geometric, material, and plate-coupling data along the A-A megathrust assembled from the Science Application for Risk Reduction (SAFRR) team (e.g., Bruns et al., 1987; Hayes et al., 2012; Johnson et al., 2004; Santini et al., 2003; Wells at al., 2003), we are able to dynamically model rupture. Adding frictional-strengthening to a region of the fault reduces both average slip and free surface displacement above the strengthening zone, with the magnitude of the reductions depending on the strengthening zone location. Corresponding tsunami models, which use a finite difference method to solve the long-wave equations (e.g., Liu et al., 1995; Satake, 2002; Shuto, 1991), match sea floor displacement, in time, to the free surface displacement from the rupture models. Tsunami models show changes in local peak amplitudes and beaming patterns for each slip distribution. Given these results, other heterogeneous parameterizations, with respect to prestress and friction, still need to be examined. Additionally, a more realistic fault geometry will likely affect the rupture dynamics. Thus, future work will incorporate stochastic stress and friction distributions as well as a more complex fault geometry based on Slab 1.0 (Hayes et al., 2012).

Movement of fine particles on an air bubble surface studied using high-speed video microscopy.

PubMed

Nguyen, Anh V; Evans, Geoffrey M

2004-05-01

A CCD high-speed video microscopy system operating at 1000 frames per second was used to obtain direct quantitative measurements of the trajectories of fine glass spheres on the surface of air bubbles. The glass spheres were rendered hydrophobic by a methylation process. Rupture of the intervening water film between a hydrophobic particle and an air bubble with the consequent formation of a three-phase contact was observed. The bubble-particle sliding attachment interaction is not satisfactorily described by the available theories. Surface forces had little effect on the particle sliding with a water film, which ruptured probably due to the submicrometer-sized gas bubbles existing at the hydrophobic particle-water interface.

Drop interaction with solid boundaries in liquid/liquid systems

NASA Astrophysics Data System (ADS)

Bordoloi, Ankur Deep

The present experimental work was motivated primarily by the CO 2 sequestration process. In a possible scenario during this process, gravity driven CO2 bubbles coalesce at an interface near the rock surface. In another scenario, trapped CO2 fluid may escape from a porous matrix overcoming interfacial force inside a pore. Based on these potential scenarios, the current research was divided into two broad experimental studies. In the first part, coalescence at a quiescent interface of two analogous fluids (silicone oil and water/glycerin mixture) was investigated for water/glycerin drops with Bond number (Bo) ~7 and Ohnesorge number ~ 0.01 using high-speed imaging and time-resolved tomographic PIV. Two perturbation cases with a solid particle wetted in oil and water/glycerin placed adjacent to the coalescing drop were considered. The results were compared with coalescence of a single drop and that of a drop neighBored by a second drop of equivalent size. Each perturbing object caused an initial tilting of the drop, influencing its rupture location, subsequent film retraction and eventual collapse behavior. Once tilted, drops typically ruptured near their lowest vertical position which was located either toward or away from the perturbing object depending on the case. The trends in local retraction speed of the ruptured film and the overall dynamics of the collapsing drops were discussed in detail. In the second part, the motion of gravity driven drops (B o~0.8-11) through a confining orifice d/D<1) was studied using high speed imaging and planar PIV. Drops of water/glycerin, surrounded by silicone oil, fall toward and encounter the orifice plate after reaching terminal speed. The effects of surface wettability were investigated for Both round-edged and sharp-edged orifices. For the round-edged case, a thin film of surrounding oil prevented the drop fluid from contacting the orifice surface, such that the flow outcomes of the drops were independent of surface wettability. For d/D<0.8, the Boundary between drop capture and release depended on a modified Bond number relating drop gravitational time scale to orifice surface tension time scale. For the sharp-edged case, contact was initiated at the orifice edge immediately upon impact, such that surface wettability influenced the drop outcome.

Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases?

USGS Publications Warehouse

Smith, D.E.; Aagaard, Brad T.; Heaton, T.H.

2005-01-01

We investigate whether a shallow-dipping thrust fault is prone to waveslip interactions via surface-reflected waves affecting the dynamic slip. If so, can these interactions create faults that are opaque to radiated energy? Furthermore, in this case of a shallow-dipping thrust fault, can incorrectly assuming a transparent fault while using dislocation theory lead to underestimates of seismic moment? Slip time histories are generated in three-dimensional dynamic rupture simulations while allowing for varying degrees of wave-slip interaction controlled by fault-friction models. Based on the slip time histories, P and SH seismograms are calculated for stations at teleseismic distances. The overburdening pressure caused by gravity eliminates mode I opening except at the tip of the fault near the surface; hence, mode I opening has no effect on the teleseismic signal. Normalizing by a Haskell-like traditional kinematic rupture, we find teleseismic peak-to-peak displacement amplitudes are approximately 1.0 for both P and SH waves, except for the unrealistic case of zero sliding friction. Zero sliding friction has peak-to-peak amplitudes of 1.6 for P and 2.0 for SH waves; the fault slip oscillates about its equilibrium value, resulting in a large nonzero (0.08 Hz) spectral peak not seen in other ruptures. These results indicate wave-slip interactions associated with surface-reflected phases in real earthquakes should have little to no effect on teleseismic motions. Thus, Haskell-like kinematic dislocation theory (transparent fault conditions) can be safety used to simulate teleseismic waveforms in the Earth.

Landslides and megathrust splay faults captured by the late Holocene sediment record of eastern Prince William Sound, Alaska

USGS Publications Warehouse

Finn, S.P.; Liberty, Lee M.; Haeussler, Peter J.; Pratt, Thomas L.

2015-01-01

We present new marine seismic‐reflection profiles and bathymetric maps to characterize Holocene depositional patterns, submarine landslides, and active faults beneath eastern and central Prince William Sound (PWS), Alaska, which is the eastern rupture patch of the 1964 Mw 9.2 earthquake. We show evidence that submarine landslides, many of which are likely earthquake triggered, repeatedly released along the southern margin of Orca Bay in eastern PWS. We document motion on reverse faults during the 1964 Great Alaska earthquake and estimate late Holocene slip rates for these growth faults, which splay from the subduction zone megathrust. Regional bathymetric lineations help define the faults that extend 40–70 km in length, some of which show slip rates as great as 3.75  mm/yr. We infer that faults mapped below eastern PWS connect to faults mapped beneath central PWS and possibly onto the Alaska mainland via an en echelon style of faulting. Moderate (Mw>4) upper‐plate earthquakes since 1964 give rise to the possibility that these faults may rupture independently to potentially generate Mw 7–8 earthquakes, and that these earthquakes could damage local infrastructure from ground shaking. Submarine landslides, regardless of the source of initiation, could generate local tsunamis to produce large run‐ups along nearby shorelines. In a more general sense, the PWS area shows that faults that splay from the underlying plate boundary present proximal, perhaps independent seismic sources within the accretionary prism, creating a broad zone of potential surface rupture that can extend inland 150 km or more from subduction zone trenches.

Ultrafast laser ablation for targeted atherosclerotic plaque removal

NASA Astrophysics Data System (ADS)

Lanvin, Thomas; Conkey, Donald B.; Descloux, Laurent; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

2015-07-01

Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber.

Rupture process of a multiple main shock sequence: analysis of teleseismic, local and field observations of the Tennant Creek, Australia, earthquakes of January 22, 1988

USGS Publications Warehouse

Choy, G.L.; Bowman, J.R.

1990-01-01

On January 22, 1988, three large intraplate earthquakes (with MS 6.3, 6.4 and 6.7) occurred within a 12-hour period near Tennant Creek, Australia. Broadband displacement and velocity records of body waves from teleseismically recorded data are analyzed to determine source mechanisms, depths, and complexity of rupture of each of the three main shocks. Hypocenters of an additional 150 foreshocks and aftershocks constrained by local arrival time data and field observations of surface rupture are used to complement the source characteristics of the main shocks. The interpretation of the combined data sets suggests that the overall rupture process involved unusually complicated stress release. Rupture characteristics suggest that substantial slow slip occurred on each of the three fault interfaces that was not accompanied by major energy release. Variation of focal depth and the strong increase of moment and radiated energy with each main shock imply that lateral variations of strength were more important than vertical gradients of shear stress in controlling the progression of rupture. -from Authors

Active faulting in the central Betic Cordillera (Spain): Palaeoseismological constraint of the surface-rupturing history of the Baza Fault (Central Betic Cordillera, Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Castro, J.; Martin-Rojas, I.; Medina-Cascales, I.; García-Tortosa, F. J.; Alfaro, P.; Insua-Arévalo, J. M.

2018-06-01

This paper on the Baza Fault provides the first palaeoseismic data from trenches in the central sector of the Betic Cordillera (S Spain), one of the most tectonically active areas of the Iberian Peninsula. With the palaeoseismological data we constructed time-stratigraphic OxCal models that yield probability density functions (PDFs) of individual palaeoseismic event timing. We analysed PDF overlap to quantitatively correlate the walls and site events into a single earthquake chronology. We assembled a surface-rupturing history of the Baza Fault for the last ca. 45,000 years. We postulated six alternative surface rupturing histories including 8-9 fault-wide earthquakes. We calculated fault-wide earthquake recurrence intervals using Monte Carlo. This analysis yielded a 4750-5150 yr recurrence interval. Finally, compared our results with the results from empirical relationships. Our results will provide a basis for future analyses of more of other active normal faults in this region. Moreover, our results will be essential for improving earthquake-probability assessments in Spain, where palaeoseismic data are scarce.

Paleoseismologic evidence for large-magnitude (Mw 7.5-8.0) earthquakes on the Ventura blind thrust fault: Implications for multifault ruptures in the Transverse Ranges of southern California

USGS Publications Warehouse

McAuliffe, Lee J.; Dolan, James F.; Rhodes, Edward J.; Hubbard, Judith; Shaw, John H.; Pratt, Thomas L.

2015-01-01

Detailed analysis of continuously cored boreholes and cone penetrometer tests (CPTs), high-resolution seismic-reflection data, and luminescence and 14C dates from Holocene strata folded above the tip of the Ventura blind thrust fault constrain the ages and displacements of the two (or more) most recent earthquakes. These two earthquakes, which are identified by a prominent surface fold scarp and a stratigraphic sequence that thickens across an older buried fold scarp, occurred before the 235-yr-long historic era and after 805 ± 75 yr ago (most recent folding event[s]) and between 4065 and 4665 yr ago (previous folding event[s]). Minimum uplift in these two scarp-forming events was ∼6 m for the most recent earthquake(s) and ∼5.2 m for the previous event(s). Large uplifts such as these typically occur in large-magnitude earthquakes in the range of Mw7.5–8.0. Any such events along the Ventura fault would likely involve rupture of other Transverse Ranges faults to the east and west and/or rupture downward onto the deep, low-angle décollements that underlie these faults. The proximity of this large reverse-fault system to major population centers, including the greater Los Angeles region, and the potential for tsunami generation during ruptures extending offshore along the western parts of the system highlight the importance of understanding the complex behavior of these faults for probabilistic seismic hazard assessment.

Static Rupture Model of the 2010 M7.2 El Mayor-Cucapah Earthquake from ALOS, ENVISAT, SPOT and GPS Data

NASA Astrophysics Data System (ADS)

Fialko, Y.; Gonzalez, A.; Gonzalez-Garcia, J. J.; Barbot, S.; Leprince, S.; Sandwell, D. T.; Agnew, D. C.

2010-12-01

The April 4, 2010 "Easter Sunday" earthquake on the US-Mexico border was the largest event to strike Southern California in the last 18 years. The earthquake occurred on a northwest trending fault close to, but not coincident with the identified 1892 Laguna Salada rupture. We investigate coseismic deformation due to the 2010 El Mayor-Cucapah earthquake using Synthetic Aperture Radar (SAR) imagery form ENVISAT and ALOS satellites, optical imagery from SPOT-5 satellite, and continuous and campaign GPS data. The earliest campaign postseismic GPS survey was conducted within days after the earthquake, and provided the near-field cosesmic offsets. Along-track SAR interferograms and amplitude cross-correlation of optical images reveal a relatively simple continuous fault trace with maximum offsets of the order of 3 meters. This is in contrast to the results of geological mapping that portrayed a complex broad zone of distributed faulting. Also, SAR data indicate that the rupture propagated bi-laterally from the epicenter near the town of Durango both to the North-West into the Cucapah mountains and to the South-East into the Mexically valley. The inferred South-East part of the rupture was subsequently field-checked and associated with several fresh scarps, although overall the earthquake fault does not have a conspicuous surface trace South-East of the hypocenter. It is worth noting that the 2010 earthquake propagated into stress shadows of prior events - the Laguna Salada earthquake that ruptured the North-West part of the fault in 1892, and several M6+ earthquakes that ruptured the South-East part of the fault over the last century. Analysis of the coseismic displacement field at the Earth's surface (in particular, the full 3-component displacement field retrieved from SAR and optical imagery) shows a pronounced asymmetry in horizontal displacements across both nodal planes. The maximum displacements are observed in the North-Eastern and South-Western quadrants. This pattern cannot be explained by oblique slip on a quasi-planar fault. Multi-parametric inversions of the space geodetic data suggest that the El Mayor-Cucapah earthquake occurred on a helix-shaped rupture, with Eastward dip in the Northern section and Westward dip in the Southern section. This interpretation is consistent with field observations of the surface rupture and aftershock data, and provides an explanation for a strong non-double-couple component suggested by the seismic moment tensor solution. The total geodetic moment of our best-fitting model is in a good agreement with the seismic moment. We will also discuss effects of the elastic structure on the inferred static rupture model, and observations of early postseismic deformation.

Investigation of UF/sub 6/ behavior in a fire

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, W.R.

Reactions between UF/sub 6/ and combustible gases and the potential for UF/sub 6/-filled cylinders to rupture when exposed to fire are addressed. Although the absence of kinetic data prevents specific identification and quantification of the chemical species formed, potential reaction products resulting from the release of UF/sub 6/ into a fire include UF/sub 4/, UO/sub 2/F/sub 2/, HF, C, CF/sub 4/,COF/sub 2/, and short chain, fluorinated or partially fluorinated hydrocarbons. Such a release adds energy to a fire relative to normal combustion reactions. Time intervals to an assumed point of rupture for UF/sub 6/-filled cylinders exposed to fire are estimatedmore » conservatively. Several related studies are also summarized, including a test series in which small UF/sub 6/-filled cylinders were immersed in fire resulting in valve failures and explosive ruptures. It is concluded that all sizes of UF/sub 6/ cylinders currently in use may rupture within 30 minutes when totally immersed in a fire. For cylinders adjacent to fires, rupture of the larger cylinders appears much less likely.« less

Influence of fault steps on rupture termination of strike-slip earthquake faults

NASA Astrophysics Data System (ADS)

Li, Zhengfang; Zhou, Bengang

2018-03-01

A statistical analysis was completed on the rupture data of 29 historical strike-slip earthquakes across the world. The purpose of this study is to examine the effects of fault steps on the rupture termination of these events. The results show good correlations between the type and length of steps with the seismic rupture and a poor correlation between the step number and seismic rupture. For different magnitude intervals, the smallest widths of the fault steps (Lt) that can terminate the rupture propagation are variable: Lt = 3 km for Ms 6.5 6.9, Lt = 4 km for Ms 7.0 7.5, Lt = 6 km for Ms 7.5 8.0, and Lt = 8 km for Ms 8.0 8.5. The dilational fault step is easier to rupture through than the compression fault step. The smallest widths of the fault step for the rupture arrest can be used as an indicator to judge the scale of the rupture termination of seismic faults. This is helpful for research on fault segmentation, as well as estimating the magnitude of potential earthquakes, and is thus of significance for the assessment of seismic risks.

Rupture directivity of microseismic events recorded during hydraulic fracture stimulations.

NASA Astrophysics Data System (ADS)

Urbancic, T.; Smith-Boughner, L.; Baig, A.; Viegas, G.

2016-12-01

We model the dynamics of a complex rupture sequence with four sub-events. These events were recorded during hydraulic fracture stimulations in a gas-bearing shale formation. With force-balance accelerometers, 4.5Hz and 15Hz instruments recording the failure history, we study the directivity of the entire rupture sequence and each sub-event. Two models are considered: unilateral and bi-lateral failures of penny shaped cracks. From the seismic moment tensors of these sub-events, we consider different potential failure planes and rupture directions. Using numerical wave-propagation codes, we generate synthetic rupture sequences with both unilateral and bi-lateral ruptures. These are compared to the four sub-events to determine the directionality of the observed failures and the sensitivity of our recording bandwidth and geometry to distinguishing between different rupture processes. The frequency of unilateral and bilateral rupture processes throughout the fracture stimulation is estimated by comparing the directivity characteristics of the modeled sub-events to other high-quality microseismic events recorded during the same stimulation program. Understanding the failure processes of these microseismic events can provide great insight into the changes in the rock mass responsible for these complex rupture processes.

High-speed rupture during the initiation of the 2015 Bonin Islands deep earthquake

NASA Astrophysics Data System (ADS)

Zhan, Z.; Ye, L.; Shearer, P. M.; Lay, T.; Kanamori, H.

2015-12-01

Among the long-standing questions on how deep earthquakes rupture, the nucleation phase of large deep events is one of the most puzzling parts. Resolving the rupture properties of the initiation phase is difficult to achieve with far-field data because of the need for accurate corrections for structural effects on the waveforms (e.g., attenuation, scattering, and site effects) and alignment errors. Here, taking the 2015 Mw 7.9 Bonin Islands earthquake (depth = 678 km) as an example, we jointly invert its far-field P waves at multiple stations for the average rupture speed during the first second of the event. We use waveforms from a closely located aftershock as empirical Green's functions, and correct for possible differences in focal mechanisms and waveform misalignments with an iterative approach. We find that the average initial rupture speed is over 5 km/s, significantly higher than the average rupture speed of 3 km/s later in the event. This contrast suggests that rupture speeds of deep earthquakes can be highly variable during individual events and may define different stages of rupture, potentially with different mechanisms.

Features of the rupture of free hanging liquid film under the action of a thermal load

NASA Astrophysics Data System (ADS)

Ovcharova, Alla S.

2011-10-01

We consider a deformation and a rupture of a thin liquid film which is hanging between two solid flat walls under the action of concentrated thermal load action. A two-dimensional model is applied to describe the motion of thin layers of viscous non-isothermal liquid under micro-gravity conditions. For flow simulation, two-dimensional Navier-Stokes equations are used. A computational analysis of the influence of thermal loads on the deformation and the rupture behavior of the thin freely hanging film is carried out. It is shown that the rupture of the thin film with generation of a droplet can occur under the thermal beam of specific width acting on the free surface of the film. The results of the model problem solutions are presented.

[Rupture of the Achilles tendon].

PubMed

Ulmar, B; Simon, S; Eschler, A; Mittlmeier, T

2014-10-01

The rupture of the Achilles tendon is the most frequent tendon rupture in humans and it is associated with increasing incidence. The main risk factor is intrinsic degeneration of the tendon. During the rupture the person feels a whiplash or dagger thrust-like pain, followed by restricted walking ability and decreased plantar flexion of the ankle. The positive Simmond/Thompson test and a palpable dent above the tendon rupture are pathognomical. Diagnostically, ultrasound of the tendon and lateral x-ray of the calcaneus (bony pull-out of the tendon insertion) are necessary. Regarding correct indication and treatment modalities, most established conservative and surgical therapies realize optimal functional results. Surgical treatment promises better primary stability and slightly earlier better functional results, but there is the potential for surgical complications. Conservative therapy is associated with higher rates of re-rupture and healing of the tendon under elongation. Therefore, therapy planning in Achilles tendon rupture should be determined based on each patient. We recommend surgical treatment in patients with higher sporting demands and in younger patients (< 50 years).

Rupture model based on non-associated plasticity

NASA Astrophysics Data System (ADS)

Pradeau, Adrien; Yoon, Jeong Whan; Thuillier, Sandrine; Lou, Yanshan; Zhang, Shunying

2018-05-01

This research work is about modeling the mechanical behavior of metallic sheets of AA6016 up to rupture using non-associated flow rule. Experiments were performed at room temperature in uniaxial tension and simple shear in different directions according to the rolling direction and an additional hydraulic bulge test. The anisotropy of the material is described by a Yld2000-2d yield surface [1], calibrated by stress ratios, and a plastic potential represented by Hill1948 [2], calibrated using Lankford coefficients. That way, the former is able to reproduce the yield stresses in different directions and the latter is able to reproduce the deformations in different directions as well [3], [4]. Indeed, the non-associated flow rule allows for the direction of the plastic flow not to be necessarily normal to the yield surface. Concerning the rupture, the macroscopic ductile fracture criterion DF2014 was used [5]. It indirectly uses the three invariants of the stress tensor by using the three following parameters: the stress triaxiality η, the Lode parameter L and the equivalent plastic strain to fracture ∈f-p . In order to be consistent with the plastic model and to add more flexibility to the p criterion, the equivalent stress σ ¯ and the equivalent strain to fracture ∈f-p have been substituted respectively as Yld2000-2d and Hill1948 in the DF2014 fracture criterion. The parameters for the fracture criterion were obtained by optimization and the fracture locus can be plotted in the (η ,L ,∈-p) space. The damage indicator D is then numerically predicted with respect of average strain values. A good correlation with the experimental results is obtained.

Field and experimental evidence for coseismic ruptures along shallow creeping faults in forearc sediments of the Crotone Basin, South Italy

NASA Astrophysics Data System (ADS)

Balsamo, Fabrizio; Aldega, Luca; De Paola, Nicola; Faoro, Igor; Storti, Fabrizio

2014-05-01

Large seismic slip occurring along shallow creeping faults in tectonically active areas represents an unsolved paradox, which is largely due to our poor understanding of the mechanics governing creeping faults, and to the lack of documented geological evidence showing how coseismic rupturing overprints creep in near-surface conditions. In this contribution we integrate field, petrophysical, mineralogical and friction data to characterize the signature of coseismic ruptures propagating along shallow creeping faults affecting unconsolidated forearc sediments of the seismically active Crotone Basin, in South Italy. Field observations of fault zones show widespread foliated cataclasites in fault cores, locally overprinted by sharp slip surfaces decorated by thin (0.5-1.5 cm) black gouge layers. Compared to foliated cataclasites, black gouges have much lower grain size, porosity and permeability, which may have facilitated slip weakening by thermal fluid pressurization. Moreover, black gouges are characterized by distinct mineralogical assemblages compatible with high temperatures (180-200°C) due to frictional heating during seismic slip. Foliated cataclasites and black gouges were also produced by laboratory friction experiments performed on host sediments at sub-seismic (≤ 0.1 m/s) and seismic (1 m/s) slip rates, respectively. Black gouges display low friction coefficients (0.3) and velocity-weakening behaviours, as opposed to high friction coefficients (0.65) and velocity-strengthening behaviours shown by the foliated cataclasites. Our results show that narrow black gouges developed within foliated cataclasites represent a potential diagnostic marker for episodic seismic activity in shallow creeping faults. These findings can help understanding the time-space partitioning between aseismic and seismic slip of faults at shallow crustal levels, impacting on seismic hazard evaluation of subduction zones and forearc regions affected by destructive earthquakes and tsunamis.

Scenario earthquake hazards for the Long Valley Caldera-Mono Lake area, east-central California (ver. 2.0, January 2018)

USGS Publications Warehouse

Chen, Rui; Branum, David M.; Wills, Chris J.; Hill, David P.

2014-06-30

As part of the U.S. Geological Survey’s (USGS) multi-hazards project in the Long Valley Caldera-Mono Lake area, the California Geological Survey (CGS) developed several earthquake scenarios and evaluated potential seismic hazards, including ground shaking, surface fault rupture, liquefaction, and landslide hazards associated with these earthquake scenarios. The results of these analyses can be useful in estimating the extent of potential damage and economic losses because of potential earthquakes and also for preparing emergency response plans.The Long Valley Caldera-Mono Lake area has numerous active faults. Five of these faults or fault zones are considered capable of producing magnitude ≥6.7 earthquakes according to the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2) developed by the 2007 Working Group on California Earthquake Probabilities (WGCEP) and the USGS National Seismic Hazard Mapping Program. These five faults are the Fish Slough, Hartley Springs, Hilton Creek, Mono Lake, and Round Valley Faults. CGS developed earthquake scenarios for these five faults in the study area and for the White Mountains Fault Zone to the east of the study area.In this report, an earthquake scenario is intended to depict the potential consequences of significant earthquakes. A scenario earthquake is not necessarily the largest or most damaging earthquake possible on a recognized fault. Rather it is both large enough and likely enough that emergency planners should consider it in regional emergency response plans. In particular, the ground motion predicted for a given scenario earthquake does not represent a full probabilistic hazard assessment, and thus it does not provide the basis for hazard zoning and earthquake-resistant building design.Earthquake scenarios presented here are based on fault geometry and activity data developed by the WGCEP, and are consistent with the 2008 Update of the United States National Seismic Hazard Maps (NSHM). Alternatives to the NSHM scenario were developed for the Hilton Creek and Hartley Springs Faults to account for different opinions in how far these two faults extend into Long Valley Caldera. For each scenario, ground motions were calculated using the current standard practice: the deterministic seismic hazard analysis program developed by Art Frankel of USGS and three Next Generation Ground Motion Attenuation (NGA) models. Ground motion calculations incorporated the potential amplification of seismic shaking by near-surface soils defined by a map of the average shear wave velocity in the uppermost 30 m (VS30) developed by CGS.In addition to ground shaking and shaking-related ground failure such as liquefaction and earthquake induced landslides, earthquakes cause surface rupture displacement, which can lead to severe damage of buildings and lifelines. For each earthquake scenario, potential surface fault displacements are estimated using deterministic and probabilistic approaches. Liquefaction occurs when saturated sediments lose their strength because of ground shaking. Zones of potential liquefaction are mapped by incorporating areas where loose sandy sediments, shallow groundwater, and strong earthquake shaking coincide in the earthquake scenario. The process for defining zones of potential landslide and rockfall incorporates rock strength, surface slope, and existing landslides, with ground motions caused by the scenario earthquake.Each scenario is illustrated with maps of seismic shaking potential and fault displacement, liquefaction, and landslide potential. Seismic shaking is depicted by the distribution of shaking intensity, peak ground acceleration, and 1.0-second spectral acceleration. One-second spectral acceleration correlates well with structural damage to surface facilities. Acceleration greater than 0.2 g is often associated with strong ground shaking and may cause moderate to heavy damage. The extent of strong shaking is influenced by subsurface fault dip and near surface materials. Strong shaking is more widespread in the hanging wall regions of a normal fault. Larger ground motions also occur where young alluvial sediments amplify the shaking. Both of these effects can lead to strong shaking that extends farther from the fault on the valley side than on the hill side.The effect of fault rupture displacements may be localized along the surface trace of the mapped earthquake fault if fault geometry is simple and the fault traces are accurately located. However, surface displacement hazards can spread over a few hundred meters to a few kilometers if the earthquake fault has numerous splays or branches, such as the Hilton Creek Fault. Faulting displacements are estimated to be about 1 meter along normal faults in the study area and close to 2 meters along the White Mountains Fault Zone.All scenarios show the possibility of widespread ground failure. Liquefaction damage would likely occur in the areas of higher ground shaking near the faults where there are sandy/silty sediments and the depth to groundwater is 6.1 meters (20 feet) or less. Generally, this means damage is most common near lakes and streams in the areas of strongest shaking. Landslide potential exists throughout the study region. All steep slopes (>30 degrees) present a potential hazard at any level of shaking. Lesser slopes may have landslides within the areas of the higher ground shaking. The landslide hazard zones also are likely sources for snow avalanches during winter months and for large boulders that can be shaken loose and roll hundreds of feet down hill, which happened during the 1980 Mammoth Lakes earthquakes.Whereas methodologies used in estimating ground shaking, liquefaction, and landslides are well developed and have been applied in published hazard maps; methodologies used in estimating surface fault displacement are still being developed. Therefore, this report provides a more in-depth and detailed discussion of methodologies used for deterministic and probabilistic fault displacement hazard analyses for this project.

Temporal evolution of surface rupture deduced from coseismic multi-mode secondary fractures: Insights from the October 8, 2005 (Mw 7.6) Kashmir earthquake, NW Himalaya

NASA Astrophysics Data System (ADS)

Sayab, Mohammad; Khan, Muhammad Asif

2010-10-01

Detailed rupture-fracture analyses of some of the well-studied earthquakes have revealed that the geometrical arrangement of secondary faults and fractures can be used as a geological tool to understand the temporal evolution of slip produced during the mainshock. The October 8, 2005 Mw 7.6 Kashmir earthquake, NW Himalaya, surface rupture provides an opportunity to study a complex network of secondary fractures developed on the hanging wall of the fault scarp. The main fault scarp is clearly thrust-type, rupture length is ~ 75 ± 5 km and the overall trend of the rupture is NW-SE. We present the results of our detailed structural mapping of secondary faults and fractures at 1:100 scale, on the hanging wall of the southern end of the rupture in the vicinity of the Sar Pain. Secondary ruptures can be broadly classified as two main types, 1) normal faults and, (2) right-lateral strike-slip 'Riedel' fractures. The secondary normal faults are NW-SE striking, with a maximum 3.3 meter vertical displacement and 2.5 meter horizontal displacement. Estimated total horizontal extension across the secondary normal faults is 3.1-3.5%. We propose that the bending-moment and coseismic stress relaxation can explain the formation of secondary normal faults on the hanging wall of the thrust fault. The strike-slip 'Riedel' fractures form distinct sets of tension (T) and shear fractures (R', R, Y) with right-lateral displacement. Field observations revealed that the 'Riedel' fractures (T) cut the secondary normal faults. In addition, there is kinematic incompatibility and magnitude mismatch between the secondary normal faults and strike-slip 'Riedel' fractures. The cross-cutting relationship, geometric and magnitude incoherence implies a temporal evolution of slip from dip- to strike-slip during the mainshock faulting. The interpretation is consistent with the thrust fault plane solution with minor right-lateral strike-slip component.

Dynamic rupture models of subduction zone earthquakes with off-fault plasticity

NASA Astrophysics Data System (ADS)

Wollherr, S.; van Zelst, I.; Gabriel, A. A.; van Dinther, Y.; Madden, E. H.; Ulrich, T.

2017-12-01

Modeling tsunami-genesis based on purely elastic seafloor displacement typically underpredicts tsunami sizes. Dynamic rupture simulations allow to analyse whether plastic energy dissipation is a missing rheological component by capturing the complex interplay of the rupture front, emitted seismic waves and the free surface in the accretionary prism. Strike-slip models with off-fault plasticity suggest decreasing rupture speed and extensive plastic yielding mainly at shallow depths. For simplified subduction geometries inelastic deformation on the verge of Coulomb failure may enhance vertical displacement, which in turn favors the generation of large tsunamis (Ma, 2012). However, constraining appropriate initial conditions in terms of fault geometry, initial fault stress and strength remains challenging. Here, we present dynamic rupture models of subduction zones constrained by long-term seismo-thermo-mechanical modeling (STM) without any a priori assumption of regions of failure. The STM model provides self-consistent slab geometries, as well as stress and strength initial conditions which evolve in response to tectonic stresses, temperature, gravity, plasticity and pressure (van Dinther et al. 2013). Coseismic slip and coupled seismic wave propagation is modelled using the software package SeisSol (www.seissol.org), suited for complex fault zone structures and topography/bathymetry. SeisSol allows for local time-stepping, which drastically reduces the time-to-solution (Uphoff et al., 2017). This is particularly important in large-scale scenarios resolving small-scale features, such as the shallow angle between the megathrust fault and the free surface. Our dynamic rupture model uses a Drucker-Prager plastic yield criterion and accounts for thermal pressurization around the fault mimicking the effect of pore pressure changes due to frictional heating. We first analyze the influence of this rheology on rupture dynamics and tsunamigenic properties, i.e. seafloor displacement, in 2D. Finally, we use the same rheology in a large-scale 3D scenario of the 2004 Sumatra earthquake to shed light to the source process that caused the subsequent devastating tsunami.

High-intensity focused ultrasound ablation around the tubing

PubMed Central

Siu, Jun Yang; Liu, Chenhui

2017-01-01

High-intensity focused ultrasound (HIFU) has been emerging as an effective and noninvasive modality in cancer treatment with very promising clinical results. However, a small vessel in the focal region could be ruptured, which is an important concern for the safety of HIFU ablation. In this study, lesion formation in the polyacrylamide gel phantom embedded with different tubing (inner diameters of 0.76 mm and 3 mm) at varied flow speeds (17–339 cm/s) by HIFU ablation was photographically recorded. Produced lesions have decreased length (~30%) but slightly increased width (~6%) in comparison to that without the embedded tubing. Meanwhile, bubble activities during the exposures were measured by passive cavitation detection (PCD) at the varied pulse repetition frequency (PRF, 10–30 Hz) and duty cycle (DC, 10%-20%) of the HIFU bursts. High DC and low flow speed were found to produce stronger bubble cavitation whereas no significant influence of the PRF. In addition, high-speed photography illustrated that the rupture of tubing was produced consistently after the first HIFU burst within 20 ms and then multiple bubbles would penetrate into the intraluminal space of tubing through the rupture site by the acoustic radiation force. Alignment of HIFU focus to the anterior surface, middle, and posterior surface of tubing led to different characteristics of vessel rupture and bubble introduction. In summary, HIFU-induced vessel rupture is possible as shown in this phantom study; produced lesion sizes and shapes are dependent on the focus alignment to the tubing, flow speed, and tubing properties; and bubble cavitation and the formation liquid jet may be one of the major mechanisms of tubing rupture as shown in the high-speed photography. PMID:29161293

High-intensity focused ultrasound ablation around the tubing.

PubMed

Siu, Jun Yang; Liu, Chenhui; Zhou, Yufeng

2017-01-01

High-intensity focused ultrasound (HIFU) has been emerging as an effective and noninvasive modality in cancer treatment with very promising clinical results. However, a small vessel in the focal region could be ruptured, which is an important concern for the safety of HIFU ablation. In this study, lesion formation in the polyacrylamide gel phantom embedded with different tubing (inner diameters of 0.76 mm and 3 mm) at varied flow speeds (17-339 cm/s) by HIFU ablation was photographically recorded. Produced lesions have decreased length (~30%) but slightly increased width (~6%) in comparison to that without the embedded tubing. Meanwhile, bubble activities during the exposures were measured by passive cavitation detection (PCD) at the varied pulse repetition frequency (PRF, 10-30 Hz) and duty cycle (DC, 10%-20%) of the HIFU bursts. High DC and low flow speed were found to produce stronger bubble cavitation whereas no significant influence of the PRF. In addition, high-speed photography illustrated that the rupture of tubing was produced consistently after the first HIFU burst within 20 ms and then multiple bubbles would penetrate into the intraluminal space of tubing through the rupture site by the acoustic radiation force. Alignment of HIFU focus to the anterior surface, middle, and posterior surface of tubing led to different characteristics of vessel rupture and bubble introduction. In summary, HIFU-induced vessel rupture is possible as shown in this phantom study; produced lesion sizes and shapes are dependent on the focus alignment to the tubing, flow speed, and tubing properties; and bubble cavitation and the formation liquid jet may be one of the major mechanisms of tubing rupture as shown in the high-speed photography.

Mechanics of Multifault Earthquake Ruptures

NASA Astrophysics Data System (ADS)

Fletcher, J. M.; Oskin, M. E.; Teran, O.

2015-12-01

The 2010 El Mayor-Cucapah earthquake of magnitude Mw 7.2 produced the most complex rupture ever documented on the Pacific-North American plate margin, and the network of high- and low-angle faults activated in the event record systematic changes in kinematics with fault orientation. Individual faults have a broad and continuous spectrum of slip sense ranging from endmember dextral strike slip to normal slip, and even faults with thrust sense of dip slip were commonly observed in the aftershock sequence. Patterns of coseismic slip are consistent with three-dimensional constrictional strain and show that integrated transtensional shearing can be accommodated in a single earthquake. Stress inversions of coseismic surface rupture and aftershock focal mechanisms define two coaxial, but permuted stress states. The maximum (σ1) and intermediate (σ2) principal stresses are close in magnitude, but flip orientations due to topography- and density-controlled gradients in lithostatic load along the length of the rupture. Although most large earthquakes throughout the world activate slip on multiple faults, the mechanical conditions of their genesis remain poorly understood. Our work attempts to answer several key questions. 1) Why do complex fault systems exist? They must do something that simple, optimally-oriented fault systems cannot because the two types of faults are commonly located in close proximity. 2) How are faults with diverse orientations and slip senses prepared throughout the interseismic period to fail spontaneously together in a single earthquake? 3) Can a single stress state produce multi-fault failure? 4) Are variations in pore pressure, friction and cohesion required to produce simultaneous rupture? 5) How is the fabric of surface rupture affected by variations in orientation, kinematics, total geologic slip and fault zone architecture?

The Influence of TiO2 Addition on the Modulus of Rupture of Alumina-Magnesia Refractory Castables

NASA Astrophysics Data System (ADS)

Yuan, Wenjie; Deng, Chengji; Zhu, Hongxi

2015-08-01

The addition of TiO2 to alumina-magnesia refractory castables could accelerate the in situ spinel and calcium hexa-aluminate (CA6) formation and change the phase evolution, which will have direct effect on the overall modulus of rupture values. The cold (CMOR) and hot (HMOR) modulus of rupture, thermal expansion, and elastic modulus of alumina-magnesia refractory castables with different amounts of TiO2 were measured. The correlation of CMOR, theoretical strength, fracture toughness, and the fractal dimension of the fracture surface for these compositions were investigated. HMOR data were described using the model based on Varshni approach and Adam-Gibbs theory. The influence of TiO2 addition on the modulus of rupture of alumina-magnesia refractory castables was related to microcracks derived from expansive phase formation and pore filling or viscous bridging due to the presence of liquid phase at high temperature. The contribution of the above factors to the modulus of rupture for castables varied with the temperature.

The deep Peru 2015 doublet earthquakes

NASA Astrophysics Data System (ADS)

Ruiz, S.; Tavera, H.; Poli, P.; Herrera, C.; Flores, C.; Rivera, E.; Madariaga, R.

2017-11-01

On 24 November 2015 two events of magnitude Mw 7.5 and Mw 7.6 occurred at 600 km depth under the Peru-Brazil boundary. These two events were separated in time by 300 s. Deep event doublets occur often under South America. The characteristics that control these events and the dynamic interaction between them are an unresolved problem. We used teleseismic and regional data, situated above the doublet, to perform source inversion in order to characterize their ruptures. The overall resemblance between these two events suggests that they share similar rupture process. They are not identical but occur on the same fault surface dipping westward. Using a P-wave stripping and stretching method we determine rupture speed of 2.25 km/s. From regional body wave inversion we find that stress drop is similar for both events, they differ by a factor of two. The similarity in geometry, rupture velocity, stress drop and radiated energy, suggests that these two events looked like simple elliptical ruptures that propagated like classical sub-shear brittle cracks.

Spatiotemporal Dynamics of Adenovirus Membrane Rupture and Endosomal Escape

PubMed Central

Maier, Oana; Marvin, Shauna A.; Wodrich, Harald; Campbell, Edward M.

2012-01-01

A key step in adenovirus cell entry is viral penetration of cellular membranes to gain access to the cytoplasm and deliver the genome to the nucleus. Yet little is known about this important event in the adenoviral life cycle. Using the cytosolic protein galectin-3 (gal3) as a marker of membrane rupture with both live- and fixed-cell imaging, we demonstrate that in the majority of instances, exposure of pVI and recruitment of gal3 to ruptured membranes occur early at or near the cell surface and occur minimally in EEA-1-positive (EEA-1+) early endosomes or LAMP-1+ late endosomes/lysosomes. Live-cell imaging of Ad5 egress from gal3+ endosomes occurs most frequently from perinuclear locations. While the Ad5 capsid is observed escaping from gal3+ endosomes, pVI appears to remain associated with the gal3+ ruptured endosomes. Thus, Ad5 membrane rupture and endosomal escape appear to be both spatially and temporally distinct events. PMID:22855481

Paleoseismic evidence for dynamic surface rupturing in an intraplate setting (Lower Rhine Embayment, central Europe)

NASA Astrophysics Data System (ADS)

Kuebler, S.; Friedrich, A. M.; Strecker, M. R.

2011-12-01

One of the most enigmatic problems in intraplate earthquake geology is the spatio-temporal recurrence pattern of large earthquakes. Intraplate regions such as the New Madrid seismic zone or the central European rift system are subject to considerable seismic hazards, because fault activity is highly disparate in space and time and our knowledge about the recurrence of large earthquakes is still rudimentary. The current debate in central Europe ranges from slip dominated by repeated large coseismic events to slip dominated by aseismic creep. Here, field evidence in support of the former is sparse, and hence, some authors concluded that many faults move by slow aseismic creep rather than by ground rupturing earthquakes. We report new results from a paleoseismic study carried out in the Lower Rhine Embayment across a subsidiary normal fault in the area of Germany's largest historical earthquake (1756 AD, ML 6.2±0.2) that clearly revealed field evidence of dynamic surface faulting. At the trench site, the fault is covered by <5 m-thick Holocene fluvial gravel and flood deposits overlaying Devonian shale. We mapped a surface offset of ~1 m and a ~10 m wide zone of localized deformation expressed by abundant fractures with aligned and broken clasts extending vertically throughout the entire gravel. Mapping of 237 fractured clasts and the long-axis orientation of ~10.000 clasts defines a deformation zone coinciding with the surface offset and two offset markers within the gravel layers. We interpret these features as the result of coseismic deformation at the near-surface end of the rupture. We rule out alternative processes which may lead to fracturing of pebbles such as freeze-thaw weathering or sediment loading effects, since both the gravel fabric and fracture planes coincide well with the fault orientation. We preclude slow deformation due to aseismic creep as governing process to cause rupturing of pebbles this close to the surface, as this would require an overburden stress of several hundreds of meters according to modelling results (e. g. Eidelmann, 1992, Geology). With a significantly smaller overburden, as in this study, a high differential acceleration force, such as a shock wave produced by an earthquake rupture or a seismic wave would be needed to overcome the pebble's shear resistance. Preliminary radiocarbon data bracket the youngest event horizon to Latest Holocene age. In conclusion, we identified coseismic deformation at the trench site, because special conditions produced a number of features not usually observed in other fault exposures. The thin sedimentary cover (<5 m) above basement rocks and the high groundwater table, which may reduce the shear strength of the pebbles, may have played an important role in producing this deformation pattern. Our results imply that large surface rupturing earthquakes in low-strain intraplate regions may be more common than previously thought.

Interaction of the subduction process and forearc tectonics: An example from the active N - Chilean margin

NASA Astrophysics Data System (ADS)

Victor, P.; Sobiesiak, M.

2005-12-01

Convergent plate boundaries at continental margins belong to the tectonically most active areas on earth and are endangered by devastating earthquakes and tsunamis. The north Chilean margin is a high strain continental margin driven by fast plate convergence rate. The greatest amount of strain is accommodated along the subduction interface. Nevertheless there is extensive crustal deformation obvious by surface ruptures along reactivated segments of large fault systems and vertical surface motions reflecting the interaction between subducting and overriding plates. The historical seismicity record indicates that great earthquakes affect the Chilean Forearc with recurrence intervals of about 112+/- 21 y . The last great event in northern Chile occurred in 1995 near Antofagasta. The Mw= 8.0 event ruptured the subduction interface 180 km along strike with an average slip of about 5m in the depth interval between 10-50 km. From careful evaluation of the aftershock sequence by examining the different catagories of aftershock focal mechanisms we can define three segments of the seismogenic zone affected by the Antofagasta main shock. The non-ruptured northern segment beneath Mejillones Peninsula is seperated by a broad transition zone from the central segment which hosts the earthquakes' rupture plane. The southern fault plane boundary is identified by linear alignment of all apparent aftershock mechanisms. Along this southern boundary the strike slip mechanisms are exclusively left lateral whereas the strike slip mechanisms along the northern transition zone are right lateral. The orientations of summed moment tensors calculated from aftershock fault plane solutions on the northern segment and in the northern transition zone differ from the orientations exhibited by moment tensors on the central segment. This might indicate a rotational component in the coseismic movement of the ruptured segment relative to the non-ruptured segment. The observed segmentation of the downgoing plate correlates well with changes in the coseismic surface displacement field and coseismic rotations derived from GPS data (Allmendinger et al. in press). We can localize a transition zone at Mejillones peninsula (23,5°S) striking approximately N 80°E dominated by clockwise vertical axis rotations also marked by rotations of the summed moment tensors on the downgoing plate. The calculated strain tensor for this transition zone does not correspond with long term surface deformation, implying that coseismic as well as early postseismic effects on the subduction interface do not contribute to long term deformation of crustal fault zones. The Antofagasta earthquake took place just south of the large 1877 gap which extends from southern Peru to Mejillones Peninsula, being the surface expression of a barrier seperating the Antofagasta fault plane from the expected future fault plane. From our studies of the Antofagasta subduction zone and the surface displacement field we hope to find evidences for interface-crust-surface interactions which can be extrapolated also to the 1877 gap.

Experimental Modeling of Dynamic Shallow Dip-Slip Faulting

NASA Astrophysics Data System (ADS)

Uenishi, K.

2010-12-01

In our earlier study (AGU 2005, SSJ 2005, JPGU 2006), using a finite difference technique, we have conducted some numerical simulations related to the source dynamics of shallow dip-slip earthquakes, and suggested the possibility of the existence of corner waves, i.e., shear waves that carry concentrated kinematic energy and generate extremely strong particle motions on the hanging wall of a nonvertical fault. In the numerical models, a dip-slip fault is located in a two-dimensional, monolithic linear elastic half space, and the fault plane dips either vertically or 45 degrees. We have investigated the seismic wave field radiated by crack-like rupture of this straight fault. If the fault rupture, initiated at depth, arrests just below or reaches the free surface, four Rayleigh-type pulses are generated: two propagating along the free surface into the opposite directions to the far field, the other two moving back along the ruptured fault surface (interface) downwards into depth. These downward interface pulses may largely control the stopping phase of the dynamic rupture, and in the case the fault plane is inclined, on the hanging wall the interface pulse and the outward-moving Rayleigh surface pulse interact with each other and the corner wave is induced. On the footwall, the ground motion is dominated simply by the weaker Rayleigh pulse propagating along the free surface because of much smaller interaction between this Rayleigh and the interface pulse. The generation of the downward interface pulses and corner wave may play a crucial role in understanding the effects of the geometrical asymmetry on the strong motion induced by shallow dip-slip faulting, but it has not been well recognized so far, partly because those waves are not expected for a fault that is located and ruptures only at depth. However, the seismological recordings of the 1999 Chi-Chi, Taiwan, the 2004 Niigata-ken Chuetsu, Japan, earthquakes as well as a more recent one in Iwate-Miyagi Inland, Japan in 2008, for example, seem to support the need for careful mechanical consideration. In this contribution, utilizing two-dimensional dynamic photoelasticity in conjunction with high speed digital cinematography, we try to perform "fully controlled" laboratory experiments of dip-slip faulting and observe the propagation of interface pulses and corner waves mentioned above. A birefringent material containing a (model) dip-slip fault plane is prepared, and rupture is initiated in that material using an Nd:YAG laser system, and the evolution of time-dependent isochromatic fringe patterns (contours of maximum in-plane shear stress) associated with the dynamic process of shallow dip-slip faulting is recorded. Use of Nd:YAG laser pulses, instead of ignition of explosives, for rupture initiation may enhance the safety of laboratory fracture experiments and enable us to evaluate the energy entering the material (and hence the energy balance in the system) more precisely, possibly in a more controlled way.

Pneumothorax in pregnancy secondary to ruptured pulmonary hydatid cyst.

PubMed

Ahmed, Iftikhar; Hajjar, Waseem; Alakeed, Ahmed Nageeb; Rahal, Salah; Alhariri, Zohair; Alnassar, Sami

2012-03-01

Hydatid disease in pregnancy is a rare condition. Ruptured pulmonary hydatid cyst with pneumothorax during pregnancy is potentially serious for both the patient and the fetus. Diagnosis, treatment, and the mode of delivery of the infant all present complex problems related to this event. We describe here a case of pneumothorax occurring during pregnancy secondary to ruptured pulmonary hydatid cyst with a good outcome for both the mother and the fetus.

Historical coseismic surface deformation of fluvial gravel deposits, Schafberg fault, Lower Rhine Graben, Germany

NASA Astrophysics Data System (ADS)

Kübler, Simon; Friedrich, Anke M.; Gold, Ryan D.; Strecker, Manfred R.

2018-03-01

Intraplate earthquakes pose a significant seismic hazard in densely populated rift systems like the Lower Rhine Graben in Central Europe. While the locations of most faults in this region are well known, constraints on their seismogenic potential and earthquake recurrence are limited. In particular, the Holocene deformation history of active faults remains enigmatic. In an exposure excavated across the Schafberg fault in the southwestern Lower Rhine Graben, south of Untermaubach, in the epicentral region of the 1756 Düren earthquake ( M L 6.2), we mapped a complex deformation zone in Holocene fluvial sediments. We document evidence for at least one paleoearthquake that resulted in vertical surface displacement of 1.2 ± 0.2 m. The most recent earthquake is constrained to have occurred after 815 AD, and we have modeled three possible earthquake scenarios constraining the timing of the latest event. Coseismic deformation is characterized by vertical offset of sedimentary contacts distributed over a 10-m-wide central damage zone. Faults were identified where they fracture and offset pebbles in the vertically displaced gravel layers and fracture orientation is consistent with the orientation of the Schafberg fault. This study provides the first constraint on the most recent surface-rupturing earthquake on the Schafberg fault. We cannot rule out that this fault acted as the source of the 1756 Düren earthquake. Our study emphasizes the importance of, and the need for, paleoseismic studies in this and other intracontinental regions, in particular on faults with subtle geomorphic expression that would not typically be recognized as being potentially seismically active. Our study documents textural features in unconsolidated sediment that formed in response to coseismic rupturing of the underlying bedrock fault. We suggest that these features, e.g., abundant oriented transgranular fractures in their context, should be added to the list of criteria used to identify a fault as potentially active. Such information would result in an increase of the number of potentially active faults that contribute to seismic hazards of intracontinental regions.

"Immortal" liquid film formed by colliding bubble at oscillating solid substrates

NASA Astrophysics Data System (ADS)

Zawala, Jan

2016-05-01

This paper presents an experimental study of the behavior of an ascending air bubble (equivalent radius 0.74 mm) colliding with a solid substrate. The substrate is either motionless or oscillating with a precisely adjusted acceleration, slightly higher than gravity. It is shown that the stability of the liquid film formed between the striking bubble and the solid surface depends not only on the hydrophobic/hydrophilic properties of the solid but also on the energetic interrelations in the system. The results indicate that the rupture of the bubble and its attachment at a smooth hydrophobic solid surface are related to the viscous dissipation of energy, leading to a gradual decrease in the bubble deformation, and in consequence in the radius of the formed separating liquid film. When the film radius is small enough, the bubble ruptures and attaches to the hydrophobic solid surface. Moreover, it is shown that when the bubble deformations are forced to be constant, by applying properly adjusted oscillations of the solid substrate (energy supply conditions), bubble rupture can be prevented and a constant bubble bouncing is observed, irrespective of the hydrophobic/hydrophilic properties of the solid substrate. Under such energy supply conditions, the liquid film can be considered "immortal." The numerical calculations performed for the respective system, in which constant kinetic energy is induced, confirm that the liquid film can persist indefinitely owing to its constant radius, which is too large to reach the critical thickness for rupture during the collision time.

Rupture process of the M 7.9 Denali fault, Alaska, earthquake: Subevents, directivity, and scaling of high-frequency ground motions

USGS Publications Warehouse

Frankel, A.

2004-01-01

Displacement waveforms and high-frequency acceleration envelopes from stations at distances of 3-300 km were inverted to determine the source process of the M 7.9 Denali fault earthquake. Fitting the initial portion of the displacement waveforms indicates that the earthquake started with an oblique thrust subevent (subevent # 1) with an east-west-striking, north-dipping nodal plane consistent with the observed surface rupture on the Susitna Glacier fault. Inversion of the remainder of the waveforms (0.02-0.5 Hz) for moment release along the Denali and Totschunda faults shows that rupture proceeded eastward on the Denali fault, with two strike-slip subevents (numbers 2 and 3) centered about 90 and 210 km east of the hypocenter. Subevent 2 was located across from the station at PS 10 (Trans-Alaska Pipeline Pump Station #10) and was very localized in space and time. Subevent 3 extended from 160 to 230 km east of the hypocenter and had the largest moment of the subevents. Based on the timing between subevent 2 and the east end of subevent 3, an average rupture velocity of 3.5 km/sec, close to the shear wave velocity at the average rupture depth, was found. However, the portion of the rupture 130-220 km east of the epicenter appears to have an effective rupture velocity of about 5.0 km/ sec, which is supershear. These two subevents correspond approximately to areas of large surface offsets observed after the earthquake. Using waveforms of the M 6.7 Nenana Mountain earthquake as empirical Green's functions, the high-frequency (1-10 Hz) envelopes of the M 7.9 earthquake were inverted to determine the location of high-frequency energy release along the faults. The initial thrust subevent produced the largest high-frequency energy release per unit fault length. The high-frequency envelopes and acceleration spectra (>0.5 Hz) of the M 7.9 earthquake can be simulated by chaining together rupture zones of the M 6.7 earthquake over distances from 30 to 180 km east of the hypocenter. However, the inversion indicates that there was relatively little high-frequency energy generated along the 60-km portion of the Totschunda fault on the east end of the rupture.

Sulfide Stress Cracking and Electrochemical Corrosion of Precipitation Hardening Steel After Plasma Oxy-Nitriding

NASA Astrophysics Data System (ADS)

Granda-Gutiérrez, E. E.; Díaz-Guillén, J. C.; Díaz-Guillén, J. A.; González, M. A.; García-Vázquez, F.; Muñóz, R.

2014-11-01

In this paper, we present the results of a duplex plasma nitriding followed by an oxidizing stage process (which is also referred as oxy-nitriding) on the corrosion behavior of a 17-4PH precipitation hardening stainless steel. The formation of both, expanded martensite (b.c.t. α'N-phase) and chromium oxide (type Cr2O3) in the subsurface of oxy-nitrided samples at specific controlled conditions, leads in a noticeable increasing in the time-to-rupture during the sulfide stress cracking test, in comparison with an untreated reference sample. Oxy-nitriding improves the corrosion performance of the alloy when it is immersed in solutions saturated by sour gas, which extends the application potential of this type of steel in the oil and gas extraction and processing industry. The presence of the oxy-nitrided layer inhibits the corrosion process that occurs in the near-surface region, where hydrogen is liberated after the formation of iron sulfides, which finally produces a fragile fracture by micro-crack propagation; the obtained results suggest that oxy-nitriding slows this process, thus delaying the rupture of the specimen. Moreover, oxy-nitriding produces a hard, sour gas-resistant surface, but do not significantly affect the original chloride ion solution resistance of the material.

On Critical States, Rupture States and Interlocking Strength of Granular Materials.

PubMed

Szalwinski, Chris M

2017-07-27

The Mohr-Coulomb theory of strength identifies cohesion and internal friction as the two principal contributions to the shear strength of a granular material. The contribution of cohesion in over-compacted granular materials has been challenged and replacing cohesion with interlocking has been proposed. A theory of rupture strength that includes interlocking is derived herein. The physics-chemistry concept of critical state is elaborated to accommodate granular materials, based on empirical definitions established in the fields of soil mechanics and bulk solids' flow. A surface in state space, called the critical compaction surface, separates over-compacted states from lightly compacted states. The intersection of this surface with the Mohr-Coulomb envelope forms the critical state surface for a granular material. The rupture strength of an over-compacted granular material is expressed as the sum of cohesion, internal friction and interlocking strength. Interlocking strength is the shear strength contribution due to over-compaction and vanishes at critical state. The theory allows migrations from one critical state to another. Changes in specific volume during such migrations are related to changes in mean-normal effective stress and uncoupled from changes in shearing strain. The theory is reviewed with respect to two established research programs and underlying assumptions are identified.

Direct measurement of the breakdown slip from near-fault strong motion data

NASA Astrophysics Data System (ADS)

Cruz-Atienza, V. M.; Olsen, K. B.; Dalguer, L. A.

2007-12-01

Obtaining reliable estimates of the frictional behaviour on earthquake faults is a fundamental task, particularly the breakdown slip Dc, which has an important role on rupture propagation through the earthquake energy budget. Several studies have attempted to estimate Dc indirectly from kinematical analysis of fault ruptures (e.g., Ide and Takeo, JGR, 1997). However, such estimates are complicated because of both the limited band-width of the observed seismograms used to image the rupture process and the rapid decay of high frequencies with distance from the fault. Mikumo et al. (BSSA, 2003) proposed a method to estimate Dc on the fault plane as the slip at the time of the peak sliprate function (Dc'). Fukuyama and Mikumo (GRL, 2007) proposed to extend this method beyond the fault plane, by estimating Dc as twice the rake-parallel particle displacement at the time of the peak particle velocity. The factor of two arises from an equal amount of opposite displacement on either side of the fault. They concluded that such method allows reliable Dc' estimates with negligible dependence on the perpendicular distance from the fault, and used it to obtain Dc' estimates for the 2000 M6.6 Tottori (0.3 m) and the 2002 M7.9 Denali (2.5 m) earthquakes. The study by Fukuyama and Mikumo was based on simple two-dimensional Green's functions in a homogeneous full space for an anti-plane kinematic crack, and suffers from three fundamental omissions: 1) the free surface and heterogeneous structure, 2) the finiteness of the rupture surface and 3) the dynamic rupture complexity of real 3D earthquakes. Here, we re-examine the methodology proposed by Fukuyama and Mikumo by means of a more realistic approach. We use spontaneous rupture propagation simulated by a recently developed and highly accurate approach, namely the staggered-grid split-node (SGSN) method in a fourth-order staggered- grid finite difference method (Dalguer and Day, JGR, 2007). We assume a vertical strike-slip fault governed by both linear and non-linear slip-weakening friction laws. Our results show that both the free surface and the stopping phases strongly affect Dc estimates. The particle motion recorded by surface instruments is amplified roughly by a factor of two due to the presence of the free surface. As a consequence, the method by Fukuyama and Mikumo over-estimates Dc when applied to strong motion data recorded on the earth's surface. Moreover, contrary to the results by Fukuyama and Mikumo, we observe a strong distance-dependence of the Dc estimates perpendicular to the fault. This variation includes a minimum near the fault, increasing up to about 140% of the target Dc value at a distance 2-3 km from the fault. At further distances from the fault the Dc estimate decreases to about 60% of the target value 10 km away. This distance dependence of the Dc estimate is presumably caused mainly by stopping phases propagating from the fault boundaries. Simulations in heterogeneous media including a low-velocity layer, intrinsic attenuation (Q) and stochastic initial stress conditions allow us to asses the reliability and uncertainty involved in the method proposed by Fukuyama and Mikumo. Dc estimates under these realistic conditions are important but remain below a factor of two in most of the cases we have analyzed. In summary, the accuracy of the method is strongly affected by the presence of the free surface, finite fault extent, and likely by complexity in the velocity structure and rupture propagation.

Seismic Hazard in Haiti: A Geologic Perspective

NASA Astrophysics Data System (ADS)

Prentice, C. S.; Crone, A. J.; Gold, R. D.; Briggs, R. W.; Narcisse, R.

2012-12-01

The catastrophic M 7.0 earthquake that occurred in Haiti on 12 January 2010 highlighted the hazard associated with the Caribbean-North American plate boundary in Hispaniola. Detailed analysis and modeling of geologic, geodetic, and seismologic data showed that most of the moment release occurred on a previously unidentified, north-dipping, blind thrust fault (now named the Léogâne fault), which is north of the plate-bounding, left-lateral Enriquillo-Plantain Garden fault (EPGF). The result that the Léogâne fault was the source of the 2010 earthquake implies that the EPGF remains a significant hazard and raises the question of other potential seismic sources near Port-au-Prince (PaP). Following the earthquake, we mapped Quaternary traces of the EPGF in the field using satellite imagery, aerial photography, and LiDAR data. We identified three paleoseismic study sites along the EPGF: the Jean-Jean and Marianne sites southwest of PaP along the Momance section of the EPGF and the Riviére Grise site southeast of PaP along the Dumay section. Trenches at the Jean-Jean site show fault strands breaking nearly to the ground surface, but that did not move in the 2010 earthquake. We collected radiocarbon samples from faulted strata that we anticipate will provide constraints on the age of the most recent surface rupture. We also identified a buried channel deposit that is left-laterally offset a minimum of 3 m, and collected radiocarbon samples to constrain its age. In a natural stream cut at the Marianne site, we documented three colluvial wedges, and collected samples for optically stimulated luminescence (OSL) dating that we anticipate will provide age constraints on the three most recent earthquakes. At Riviére Grise we documented evidence for three surface ruptures in a fluvial terrace deposit, and collected OSL samples to constrain their ages. Our preliminary geomorphic analysis of a belt of low hills north of the EPGF and east of PaP suggests that these hills are young folds likely underlain by blind thrust faults. Reconnaissance field observations show that the hills are cored by folded alluvial-fan deposits of probable Quaternary age and that the folding defeated north-flowing drainages and ponded lacustrine sediment on the south flank of the folds. Radiocarbon analyses of charcoal samples collected from ponded sediments will help to constrain the age of recent deformation. These blind thrust faults are potentially additional earthquake sources that should be included in seismic hazard assessments for PaP. In our reconnaissance along the Matheux-Neiba fault north of PaP we found only weak evidence of recent deformation, and while this fault system may also be a potential earthquake source, its rate of activity is much lower than the rate on the EPGF. Because the EPGF adjacent to PaP did not rupture in 2010, and has not ruptured in at least 240 years, considerable strain remains to be released in a future earthquake, and this fault still poses a major hazard to densely populated parts of Haiti, including Port-au-Prince.

In Vitro Spoilation of Silicone-Hydrogel Soft Contact Lenses in a Model-Blink Cell.

PubMed

Peng, Cheng-Chun; Fajardo, Neil P; Razunguzwa, Trust; Radke, Clayton J

2015-07-01

We developed an in vitro model-blink cell that reproduces the mechanism of in vivo fouling of soft contact lenses. In the model-blink cell, model tear lipid directly contacts the lens surface after forced aqueous rupture, mirroring the pre-lens tear-film breakup during interblink. Soft contact lenses are attached to a Teflon holder and immersed in artificial tear solution with protein, salts, and mucins. Artificial tear-lipid solution is spread over the air/tear interface as a duplex lipid layer. The aqueous tear film is periodically ruptured and reformed by withdrawing and reinjecting tear solution into the cell, mimicking the blink-rupture process. Fouled deposits appear on the lenses after cycling, and their compositions and spatial distributions are subsequently analyzed by optical microscopy, laser ablation electrospray ionization mass spectrometry, and two-photon fluorescence confocal scanning laser microscopy. Discrete deposit (white) spots with an average size of 20 to 300 μm are observed on the studied lenses, confirming what is seen in vivo and validating the in vitro model-blink cell. Targeted lipids (cholesterol) and proteins (albumin from bovine serum) are identified in the discrete surface deposits. Both lipid and protein occur simultaneously in the surface deposits and overlap with the white spots observed by optical microscopy. Additionally, lipid and protein penetrate into the bulk of tested silicone-hydrogel lenses, likely attributed to the bicontinuous microstructure of oleophilic silicone and hydrophilic polymer phases of the lens. In vitro spoilation of soft contact lenses is successfully achieved by the model-blink cell confirming the tear rupture/deposition mechanism of lens fouling. The model-blink cell provides a reliable laboratory tool for screening new antifouling lens materials, surface coatings, and care solutions.

Surface rupture and slip distribution of the Denali and Totschunda faults in the 3 November 2002 M 7.9 earthquake, Alaska

USGS Publications Warehouse

Haeussler, Peter J.; Schwartz, David P.; Dawson, Timothy E.; Stenner, Heidi D.; Lienkaemper, James J.; Sherrod, Brian; Cinti, Francesca R.; Montone, Paola; Craw, Patricia; Crone, Anthony J.; Personius, Stephen F.

2004-01-01

The 3 November 2002 Denali fault, Alaska, earthquake resulted in 341 km of surface rupture on the Susitna Glacier, Denali, and Totschunda faults. The rupture proceeded from west to east and began with a 48-km-long break on the previously unknown Susitna Glacier thrust fault. Slip on this thrust averaged about 4 m (Crone et al., 2004). Next came the principal surface break, along 226 km of the Denali fault, with average right-lateral offsets of 4.5–5.1 m and a maximum offset of 8.8 m near its eastern end. The Denali fault trace is commonly left stepping and north side up. About 99 km of the fault ruptured through glacier ice, where the trace orientation was commonly influenced by local ice fabric. Finally, slip transferred southeastward onto the Totschunda fault and continued for another 66 km where dextral offsets average 1.6–1.8 m. The transition from the Denali fault to the Totschunda fault occurs over a complex 25-km-long transfer zone of right-slip and normal fault traces. Three methods of calculating average surface slip all yield a moment magnitude of Mw 7.8, in very good agreement with the seismologically determined magnitude of M 7.9. A comparison of strong-motion inversions for moment release with our slip distribution shows they have a similar pattern. The locations of the two largest pulses of moment release correlate with the locations of increasing steps in the average values of observed slip. This suggests that slip-distribution data can be used to infer moment release along other active fault traces.

Fault segmentation: New concepts from the Wasatch Fault Zone, Utah, USA

USGS Publications Warehouse

Duross, Christopher; Personius, Stephen F.; Crone, Anthony J.; Olig, Susan S.; Hylland, Michael D.; Lund, William R.; Schwartz, David P.

2016-01-01

The question of whether structural segment boundaries along multisegment normal faults such as the Wasatch fault zone (WFZ) act as persistent barriers to rupture is critical to seismic hazard analyses. We synthesized late Holocene paleoseismic data from 20 trench sites along the central WFZ to evaluate earthquake rupture length and fault segmentation. For the youngest (<3 ka) and best-constrained earthquakes, differences in earthquake timing across prominent primary segment boundaries, especially for the most recent earthquakes on the north-central WFZ, are consistent with segment-controlled ruptures. However, broadly constrained earthquake times, dissimilar event times along the segments, the presence of smaller-scale (subsegment) boundaries, and areas of complex faulting permit partial-segment and multisegment (e.g., spillover) ruptures that are shorter (~20–40 km) or longer (~60–100 km) than the primary segment lengths (35–59 km). We report a segmented WFZ model that includes 24 earthquakes since ~7 ka and yields mean estimates of recurrence (1.1–1.3 kyr) and vertical slip rate (1.3–2.0 mm/yr) for the segments. However, additional rupture scenarios that include segment boundary spatial uncertainties, floating earthquakes, and multisegment ruptures are necessary to fully address epistemic uncertainties in rupture length. We compare the central WFZ to paleoseismic and historical surface ruptures in the Basin and Range Province and central Italian Apennines and conclude that displacement profiles have limited value for assessing the persistence of segment boundaries but can aid in interpreting prehistoric spillover ruptures. Our comparison also suggests that the probabilities of shorter and longer ruptures on the WFZ need to be investigated.

Evidence of Multiple Ground-rupturing Earthquakes in the Past 4000 Years along the Pasuruan Fault, East Java, Indonesia

NASA Astrophysics Data System (ADS)

Marliyani, G. I.; Arrowsmith, R.; Helmi, H.

2015-12-01

Instrumental and historical records of earthquakes, supplemented by paleoeseismic constraints can help reveal the earthquake potential of an area. The Pasuruan fault is a high angle normal fault with prominent youthful scarps cutting young deltaic sediments in the north coast of East Java, Indonesia and may pose significant hazard to the densely populated region. This fault has not been considered a significant structure, and mapped as a lineament with no sense of motion. Information regarding past earthquakes along this fault is not available. The fault is well defined both in the imagery and in the field as a ~13km long, 2-50m-high scarp. Open and filled fractures and natural exposures of the south-dipping fault plane indicate normal sense of motion. We excavated two fault-perpendicular trenches across a relay ramp identified during our surface mapping. Evidence for past earthquakes (documented in both trenches) includes upward fault termination with associated fissure fills, colluvial wedges and scarp-derived debris, folding, and angular unconformities. The ages of the events are constrained by 23 radiocarbon dates on detrital charcoal. We calibrated the dates using IntCal13 and used Oxcal to build the age model of the events. Our preliminary age model indicates that since 2006±134 B.C., there has been at least five ground rupturing earthquakes along the fault. The oldest event identified in the trench however, is not well-dated. Our modeled 95th percentile ranges of the next four earlier earthquakes (and their mean) are A.D. 1762-1850 (1806), A.D. 1646-1770 (1708), A.D. 1078-1648 (1363), and A.D. 726-1092 (909), yielding a rough recurrence rate of 302±63 yrs. These new data imply that Pasuruan fault is more active than previously thought. Additional well-dated earthquakes are necessary to build a solid earthquake recurrence model. Rupture along the whole section implies a minimum earthquake magnitude of 6.3, considering 13km as the minimum surface rupture length.

Imaging the M7.9 Denali Fault Earthquake 2002 rupture at the Delta River using LiDAR, RADAR, and SASW Surface Wave Geophysics

NASA Astrophysics Data System (ADS)

Kayen, R.; Barnhardt, W.; Carkin, B.; Collins, B. D.; Grossman, E. E.; Minasian, D.; Thompson, E.

2004-12-01

The Mw 7.9 Denali fault earthquake of 3 November 2002 resulted in approximately 5.5 meters of right-lateral offset and sub-meter (0.6m average) up-to-the north vertical displacement of alluvial deposits of the Delta River. We characterize the surface rupture and shallow fault structure of the Denali fault zone at the Delta River in order to better understand these most recent displacements and to estimate the total vertical offset of alluvium above glacially scoured bedrock. To analyze deformations along the fault-trace, we performed tripod-mounted ground-based LiDAR surveys, and Spectral analysis of Surface Wave (SASW) and Ground Penetrating RADAR (GPR) geophysical investigations. These studies were performed between the Trans-Alaska Pipeline (TAPS) corridor on the terrace deposits of the eastern flanks of the Delta River valley and the steeply sloping bedrock surface on the western side of the river. To produce digital terrain models (DTM) of the surface break we used a Riegl Z210i Laser-scanner to image eight independent LiDAR scans, and ISite3D modeling software to merge these scans into three DTM surfaces. We find that using a rotating scanning-laser allows us to produce ultra-high resolution quantitative DTMs for geomorphic analysis that can be used to resolve features and detect topographic changes on a fine-scale (0.9-2.5cm). Local geo-referencing control points are established using fixed auto reflectors. The near subsurface alluvium was imaged using reflection-based (GPR). A suite of parallel and orthogonal GPR reflection lines were measured to develop block models of the surface rupture at two locations. Radar imagery clearly delineates a plane of chaotic reflectors across the rupture zone. To characterize the depth of alluvium over bedrock on either side of the fault, we used the spectral analysis of surface waves (SASW) approach to invert the near-surface shear wave velocity profile. An Alyeska Co. Catepillar D9N track-mounted dozer was used as a high-energy random-wave source for the SASW test. This source allowed us to profile to depths in excess of 200 meters on either side of the fault. We found the combination of LiDAR and GPR allows us to analyze the surface and near-surface characteristics of a complex oblique rupture across the braid bars of the Delta River. SASW-based shear wave velocity profiles on either side of the fault indicate total up-to-the north uplift on the Denali fault of between 60-90 meters since Pleistocene (?) deglaciation. This investigation is the product of a collaborative research and development agreement between the Alyeska Pipeline Services Company, Pacific Gas and Electric Company and the U.S. Geological Survey.

Period-dependent source rupture behavior of the 2011 Tohoku earthquake estimated by multi period-band Bayesian waveform inversion

NASA Astrophysics Data System (ADS)

Kubo, H.; Asano, K.; Iwata, T.; Aoi, S.

2014-12-01

Previous studies for the period-dependent source characteristics of the 2011 Tohoku earthquake (e.g., Koper et al., 2011; Lay et al., 2012) were based on the short and long period source models using different method. Kubo et al. (2013) obtained source models of the 2011 Tohoku earthquake using multi period-bands waveform data by a common inversion method and discussed its period-dependent source characteristics. In this study, to achieve more in detail spatiotemporal source rupture behavior of this event, we introduce a new fault surface model having finer sub-fault size and estimate the source models in multi period-bands using a Bayesian inversion method combined with a multi-time-window method. Three components of velocity waveforms at 25 stations of K-NET, KiK-net, and F-net of NIED are used in this analysis. The target period band is 10-100 s. We divide this period band into three period bands (10-25 s, 25-50 s, and 50-100 s) and estimate a kinematic source model in each period band using a Bayesian inversion method with MCMC sampling (e.g., Fukuda & Johnson, 2008; Minson et al., 2013, 2014). The parameterization of spatiotemporal slip distribution follows the multi-time-window method (Hartzell & Heaton, 1983). The Green's functions are calculated by the 3D FDM (GMS; Aoi & Fujiwara, 1999) using a 3D velocity structure model (JIVSM; Koketsu et al., 2012). The assumed fault surface model is based on the Pacific plate boundary of JIVSM and is divided into 384 subfaults of about 16 * 16 km^2. The estimated source models in multi period-bands show the following source image: (1) First deep rupture off Miyagi at 0-60 s toward down-dip mostly radiating relatively short period (10-25 s) seismic waves. (2) Shallow rupture off Miyagi at 45-90 s toward up-dip with long duration radiating long period (50-100 s) seismic wave. (3) Second deep rupture off Miyagi at 60-105 s toward down-dip radiating longer period seismic waves then that of the first deep rupture. (4) Deep rupture off Fukushima at 90-135 s. The dominant-period difference of the seismic-wave radiation between two deep ruptures off Miyagi may result from the mechanism that small-scale heterogeneities on the fault are removed by the first rupture. This difference can be also interpreted by the concept of multi-scale dynamic rupture (Ide & Aochi, 2005).

Cohesive zone length of metagabbro at supershear rupture velocity

NASA Astrophysics Data System (ADS)

Fukuyama, Eiichi; Xu, Shiqing; Yamashita, Futoshi; Mizoguchi, Kazuo

2016-10-01

We investigated the shear strain field ahead of a supershear rupture. The strain array data along the sliding fault surfaces were obtained during the large-scale biaxial friction experiments at the National Research Institute for Earth Science and Disaster Resilience. These friction experiments were done using a pair of meter-scale metagabbro rock specimens whose simulated fault area was 1.5 m × 0.1 m. A 2.6-MPa normal stress was applied with loading velocity of 0.1 mm/s. Near-fault strain was measured by 32 two-component semiconductor strain gauges installed at an interval of 50 mm and 10 mm off the fault and recorded at an interval of 1 MHz. Many stick-slip events were observed in the experiments. We chose ten unilateral rupture events that propagated with supershear rupture velocity without preceding foreshocks. Focusing on the rupture front, stress concentration was observed and sharp stress drop occurred immediately inside the ruptured area. The temporal variation of strain array data is converted to the spatial variation of strain assuming a constant rupture velocity. We picked up the peak strain and zero-crossing strain locations to measure the cohesive zone length. By compiling the stick-slip event data, the cohesive zone length is about 50 mm although it scattered among the events. We could not see any systematic variation at the location but some dependence on the rupture velocity. The cohesive zone length decreases as the rupture velocity increases, especially larger than √{2} times the shear wave velocity. This feature is consistent with the theoretical prediction.

The source parameters, surface deformation and tectonic setting of three recent earthquakes: thessalonki (Greece), tabas-e-golshan (iran) and carlisle (u.k.).

PubMed

King, G; Soufleris, C; Berberian, M

1981-03-01

Abstract- Three earthquakes have been studied. These are the Thessaloniki earthquake of 20th June 1978 (Ms = 6.4, Normal faulting), the Tabase-Golshan earthquake of 16th September 1978 (Ms = 7.7 Thrust faulting) and the Carlisle earth-quake of 26th December 1979 (Mb = 5.0, Thrust faulting). The techniques employed to determine source parameters included field studies of SUP face deformation, fault breaks, locations of locally recorded aftershocks and teleseismic studies including joint hypocentral location, first motion methods and waveform modelling. It is clear that these techniques applied together provide more information than the same methods used separately. The moment of the Thessaloniki earthquake determined teleseismically (Force moment 5.2 times 10(25) dyne cm. Geometric moment 1.72 times 10(8) m(3) ) is an order of magnitude greater than that determined using field data (surface ruptures and aftershock depths) (Force moment 4.5 times 10(24) dyne cm. Geometric moment 0.16 times 10(8) m(3) ). It is concluded that for this earthquake the surface rupture only partly reflects the processes on the main rupture plane. This view i s supported by a distribution of aftershocks and damage which extends well outside the region of ground rupture. However, the surface breaks consistently have the same slip vector direction as the fault plane solutions suggesting that they are in this respect related to to the main faulting and are not superficial slumping. Both field studies and waveform studies suggest a low stress drop which may explain the relatively little damage and loss of life as a result of the Thessaloniki earthquake. In contrast, the teleseismic moment of the Tabas-e-Golshan earthquake (Force moment 4.4 times 10(26) dyne cm. Geometric moment 1.5 times 10(9) m(3) ) is similar t o that determined from field studies (Force moment 10.2 times 10(26) dyne cm. Geometric moment 3.4 times 10(9) m(3) ) and the damage and after-shock distributions clearly relate to the surface faulting. It h a s also been observed that high aftershock activity appears beneath gaps in the surface rupture system. The Carlisle earthquake (Force moment 9 times 10(23) dyne cm. Geometric moment 3 times 10(6) m(3) ) produced no surface ruptures. However, dislocation model-ling suggests that surface deformation will be visible on a first order levelling line which passes very close t o the epicentre. A well controlled fault plane solution, the first in the British Isles, derived from an aftershock study shows north-south compression. All three studied earthquakes occurred along major faults which had been reactivated in geological times. The fault on which the Tabas-e-Golshan earthquake occurred could have been identified a s active from evidence of Quaternary motion and previous smaller earthquakes. However, there were no perceptible events in the 12 months preceeding the catastrophic earthquake. In both Thessaloniki and Carlisle, significant foreshocks did occur within 6 months prior to the main shock*

Effect of off-fault low-velocity elastic inclusions on supershear rupture dynamics

NASA Astrophysics Data System (ADS)

Ma, Xiao; Elbanna, A. E.

2015-10-01

Heterogeneous velocity structures are expected to affect fault rupture dynamics. To quantitatively evaluate some of these effects, we examine a model of dynamic rupture on a frictional fault embedded in an elastic full space, governed by plane strain elasticity, with a pair of off-fault inclusions that have a lower rigidity than the background medium. We solve the elastodynamic problem using the Finite Element software Pylith. The fault operates under linear slip-weakening friction law. We initiate the rupture by artificially overstressing a localized region near the left edge of the fault. We primarily consider embedded soft inclusions with 20 per cent reduction in both the pressure wave and shear wave speeds. The embedded inclusions are placed at different distances from the fault surface and have different sizes. We show that the existence of a soft inclusion may significantly shorten the transition length to supershear propagation through the Burridge-Andrews mechanism. We also observe that supershear rupture is generated at pre-stress values that are lower than what is theoretically predicted for a homogeneous medium. We discuss the implications of our results for dynamic rupture propagation in complex velocity structures as well as supershear propagation on understressed faults.

Acoustic investigation of the aperture dynamics of an elastic membrane closing an overpressurized cylindrical cavity

NASA Astrophysics Data System (ADS)

Sánchez, Claudia; Vidal, Valérie; Melo, Francisco

2015-08-01

We report an experimental study of the acoustic signal produced by the rupture of an elastic membrane that initially closes a cylindrical overpressurized cavity. This configuration has been recently used as an experimental model system for the investigation of the acoustic emission from the bursting of elongated gas bubbles rising in a conduit. Here, we investigate the effect of the membrane rupture dynamics on the acoustic signal produced by the pressure release by changing the initial tension of the membrane. The initial overpressure in the cavity is fixed at a value such that the system remains in the linear acoustic regime. For large initial membrane deformation, the rupture time τ rup is small compared to the wave propagation time in the cavity and the pressure wave inside the conduit can be fully captured by the linear theory. For low membrane tension, a hole is pierced in the membrane but its rupture does not occur. For intermediate deformation, finally, the rupture progresses in two steps: first the membrane opens slowly; then, after reaching a critical size, the rupture accelerates. A transversal wave is excited along the membrane surface. The characteristic signature of each opening dynamics on the acoustic emission is described.

Using Multi-scale Dynamic Rupture Models to Improve Ground Motion Estimates: ALCF-2 Early Science Program Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ely, Geoffrey P.

2013-10-31

This project uses dynamic rupture simulations to investigate high-frequency seismic energy generation. The relevant phenomena (frictional breakdown, shear heating, effective normal-stress fluctuations, material damage, etc.) controlling rupture are strongly interacting and span many orders of magnitude in spatial scale, requiring highresolution simulations that couple disparate physical processes (e.g., elastodynamics, thermal weakening, pore-fluid transport, and heat conduction). Compounding the computational challenge, we know that natural faults are not planar, but instead have roughness that can be approximated by power laws potentially leading to large, multiscale fluctuations in normal stress. The capacity to perform 3D rupture simulations that couple these processes willmore » provide guidance for constructing appropriate source models for high-frequency ground motion simulations. The improved rupture models from our multi-scale dynamic rupture simulations will be used to conduct physicsbased (3D waveform modeling-based) probabilistic seismic hazard analysis (PSHA) for California. These calculation will provide numerous important seismic hazard results, including a state-wide extended earthquake rupture forecast with rupture variations for all significant events, a synthetic seismogram catalog for thousands of scenario events and more than 5000 physics-based seismic hazard curves for California.« less

Rupture Dynamics and Ground Motion from Earthquakes on Rough Faults in Heterogeneous Media

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Kozdon, J. E.; Duru, K.; Dunham, E. M.

2013-12-01

Heterogeneities in the material properties of Earth's crust scatter propagating seismic waves. The effects of scattered waves are reflected in the seismic coda and depend on the amplitude of the heterogeneities, spatial arrangement, and distance from source to receiver. In the vicinity of the fault, scattered waves influence the rupture process by introducing fluctuations in the stresses driving propagating ruptures. Further variability in the rupture process is introduced by naturally occurring geometric complexity of fault surfaces, and the stress changes that accompany slip on rough surfaces. Our goal is to better understand the origin of complexity in the earthquake source process, and to quantify the relative importance of source complexity and scattering along the propagation path in causing incoherence of high frequency ground motion. Using a 2D high order finite difference rupture dynamics code, we nucleate ruptures on either flat or rough faults that obey strongly rate-weakening friction laws. These faults are embedded in domains with spatially varying material properties characterized by Von Karman autocorrelation functions and their associated power spectral density functions, with variations in wave speed of approximately 5 to 10%. Flat fault simulations demonstrate that off-fault material heterogeneity, at least with this particular form and amplitude, has only a minor influence on the rupture process (i.e., fluctuations in slip and rupture velocity). In contrast, ruptures histories on rough faults in both homogeneous and heterogeneous media include much larger short-wavelength fluctuations in slip and rupture velocity. We therefore conclude that source complexity is dominantly influenced by fault geometric complexity. To examine contributions of scattering versus fault geometry on ground motions, we compute spatially averaged root-mean-square (RMS) acceleration values as a function of fault perpendicular distance for a homogeneous medium and several heterogeneous media characterized by different statistical properties. We find that at distances less than ~6 km from the fault, RMS acceleration values from simulations with homogeneous and heterogeneous media are similar, but at greater distances the RMS values associated with heterogeneous media are larger than those associated with homogeneous media. The magnitude of this divergence increases with the amplitude of the heterogeneities. For instance, for a heterogeneous medium with a 10% standard deviation in material property values relative to mean values, RMS accelerations are ~50% larger than for a homogeneous medium at distances greater than 6 km. This finding is attributed to the scattering of coherent pulses into multiple pulses of decreased amplitude that subsequently arrive at later times. In order to understand the robustness of these results, an extension of our dynamic rupture and wave propagation code to 3D is underway.

Multi-segment earthquakes and tsunami potential of the Aleutian megathrust

USGS Publications Warehouse

Shennan, I.; Bruhn, R.; Plafker, G.

2009-01-01

Large to great earthquakes and related tsunamis generated on the Aleutian megathrust produce major hazards for both the area of rupture and heavily populated coastlines around much of the Pacific Ocean. Here we use paleoseismic records preserved in coastal sediments to investigate whether segment boundaries control the largest ruptures or whether in some seismic cycles segments combine to produce earthquakes greater than any observed since instrumented records began. Virtually the entire megathrust has ruptured since AD1900, with four different segments generating earthquakes >M8.0. The largest was the M9.2 great Alaska earthquake of March 1964 that ruptured ???800 km of the eastern segment of the megathrust. The tsunami generated caused fatalities in Alaska and along the coast as far south as California. East of the 1964 zone of deformation, the Yakutat microplate experienced two >M8.0 earthquakes, separated by a week, in September 1899. For the first time, we present evidence that earthquakes ???900 and ???1500 years ago simultaneously ruptured adjacent segments of the Aleutian megathrust and the Yakutat microplate, with a combined area ???15% greater than 1964, giving an earthquake of greater magnitude and increased tsunamigenic potential. ?? 2008 Elsevier Ltd. All rights reserved.

Neotectonics and paleoseismology of the Limón and pedro miguel faults in Panamá: earthquake hazard to the Panamá canal

USGS Publications Warehouse

Rockwell, Thomas; Gath, Edon; Gonzalez, Tania; Madden, Chris; Verdugo, Danielle; Lippincott, Caitlin; Dawson, Tim; Owen, Lewis A.; Fuchs, Markus; Cadena, Ana; Williams, Pat; Weldon, Elise; Franceschi, Pastora

2010-01-01

We present new geologic, tectonic geomorphic, and geochronologic data on the slip rate, timing, and size of past surface ruptures for the right-lateral Lim??n and Pedro Miguel faults in central Panam??. These faults are part of a system of conjugate faults that accommodate the internal deformation of Panam?? resulting from the ongoing collision of Central and South America. There have been at least three surface ruptures on the Lim??n fault in the past 950-1400 years, with the most recent during the past 365 years. Displacement in this young event is at least 1.2 m (based on trenching) and may be 1.6-2 m (based on small channel offsets). Awell-preserved 4.2 m offset suggests that the penultimate event also sustained significant displacement. The Holocene slip rate has averaged about 6 mm=yr, based on a 30-m offset terrace riser incised into a 5-ka abandoned channel. The Pedro Miguel fault has sustained three surface ruptures in the past 1600 years, the most recent being the 2 May 1621 earthquake that partially destroyed Panam?? Viejo. At least 2.1 m of slip occurred in this event near the Canal, with geomorphic offsets suggesting 2.5-3 m. The historic Camino de Cruces is offset 2.8 m, indicating multimeter displacement over at least 20 km of fault length. Channel offsets of 100-400 m, together with a climate-induced incision model, suggest a Late Quaternary slip rate of about 5 mm=yr, which is consistent with the paleoseismic results. Comparison of the timing of surface ruptures between the Lim??n and Pedro Miguel faults suggests that large earthquakes may rupture both faults with 2-3 m of displacement for over 40 km, such as is likely in earthquakes in the M 7 range. Altogether, our observations indicate that the Lim??n and Pedro Miguel faults represent a significant seismic hazard to central Panam?? and, specifically, to the Canal and Panam?? City.

Constraints on the rupture process of the 17 August 1999 Izmit earthquake

NASA Astrophysics Data System (ADS)

Bouin, M.-P.; Clévédé, E.; Bukchin, B.; Mostinski, A.; Patau, G.

2003-04-01

Kinematic and static models of the 17 August 1999 Izmit earthquake published in the literature are quite different from one to each other. In order to extract the characteristic features of this event, we determine the integral estimates of the geometry, source duration and rupture propagation of this event. Those estimates are given by the stress glut moments of total degree 2 inverting long period surface wave (LPSW) amplitude spectra (Bukchin, 1995). We draw comparisons with the integral estimates deduced from kinematic models obtained by inversion of strong motion data set and/or teleseismic body wave (Bouchon et al, 2002; Delouis et al., 2000; Yagi and Kukuchi, 2000; Sekiguchi and Iwata, 2002). While the equivalent rupture zone and the eastward directivity are consistent among all models, the LPSW solution displays a strong unilateral character of the rupture associated with a short rupture duration that is not compatible with the solutions deduced from the published models. Using a simple equivalent kinematic model, we reproduce the integral estimates of the rupture process by adjusting a few free parameters controlling the western and eastern parts of the rupture. We show that the LPSW solution strongly suggest that: - There was significant moment released on the eastern segment of the activated fault system during the Izmit earthquake; - The rupture velocity decreases on this segment. We will discuss how these results allow to enlighten the scattering of source process published for this earthquake.

New Field Observations About 19 August 1966 Varto earthquake, Eastern Turkey

NASA Astrophysics Data System (ADS)

Gurboga, S.

2013-12-01

Some destructive earthquakes in the past and even in the recent have several mysteries. For example, magnitude, epicenter location, faulting type and source fault of an earthquake have not been detected yet. One of these mysteries events is 19 August 1966 Varto earthquake in Turkey. 19 August 1966 Varto earthquake (Ms = 6.8) was an extra ordinary event at the 40 km east of junction between NAFS and EAFS which are two seismogenic system and active structures shaping the tectonics of Turkey. This earthquake sourced from Varto fault zone which are approximately 4 km width and 43 km length. It consists of faults which have parallel to sub-parallel, closely-spaced, north and south-dipping up to 85°-88° dip amount. Although this event has 6.8 (Ms) magnitude that is big enough to create a surface rupture, there was no clear surface deformation had been detected. This creates the controversial issue about the source fault and the mechanism of the earthquake. According to Wallace (1968) the type of faulting is right-lateral. On the other hand, McKenzie (1972) proposed right-lateral movement with thrust component by using the focal mechanism solution. The recent work done by Sançar et al. (2011) claimed that type of faulting is pure right-lateral strike-slip and there is no any surface rupture during the earthquake. Furthermore, they suggested that Varto segment in the Varto Fault Zone was most probably not broken in 1966 earthquake. This study is purely focused on the field geology and trenching survey for the investigation of 1966 Varto earthquake. Four fault segments have been mapped along the Varto fault zone: Varto, Sazlica, Leylekdağ and Çayçati segments. Because of the thick volcanic cover on the area around Varto, surface rupture has only been detected by trenching survey. Two trenching survey have been applied along the Yayikli and Ağaçalti faults in the Varto fault zone. Consequently, detailed geological work in the field and trenching survey indicate that a) source of 1966 earthquake is Varto segment in Varto Fault Zone, b) many of the surface deformations observed just after the earthquake is lateral-spreading and small landslides, c) surface rupture was created with 10 cm displacement at the surface with thrust component. Because of the volcanic cover and activation of many faults, ground surface rupture could not be seen clearly which has been expected after 6.8 magnitude earthquake, d) faulting type is right-lateral component with thrust component. Keywords: 1966 Varto earthquake, paleoseismology, right-lateral fault with thrust component.

Afterslip-dominated surface rupture in the M6.0 South Napa Earthquake as constrained by structure-from-motion analysis and terrestrial laser scanning

NASA Astrophysics Data System (ADS)

DeLong, S. B.; Pickering, A.; Scharer, K. M.; Hudnut, K. W.; Lienkaemper, J. J.

2014-12-01

Near-fault surface deformation associated with the August 24, 2014 M6.0 South Napa earthquake included both coseismic and post-seismic slip. Initial synthesis of field observations and initial measurement and modeling of afterslip from traditional survey methods indicate that coseismic slip was minimal (<10 cm) within 8 km northward from the epicenter but post-seismic slip, in places, approached 40 cm. We collected reconnaissance photographs using professional-grade SLR cameras from a helicopter within 12 hours after the earthquake, and a more systematic collection of air photos the day after the earthquake. We also collected terrestrial laser scanner (TLS) data two days (on August 26) and twenty-two days (on September 22) after the earthquake along a 0.5 km length of the main fault trace, just south of State Highway 12. This study site is 6 km north of the southern end of the 15 km long surface rupture and 5 km south of the highest measured co-seismic slip. We used structure-from-motion (SfM) methods to mosaic, orthorectify, and generate dense point clouds from the photos. SfM data corroborates survey-based ground observations of limited (~5 cm or less) coseismic slip along the fault trace between CA State Highway 12 and Withers Road, on discontinuous left-stepping en echelon ruptures. By August 26, the surface rupture became nearly continuous, and cultural features extracted from the TLS point clouds indicate horizontal slip magnitudes between 15 and 27 cm, increasing northward. By September 22, slip magnitudes had increased to between 26 and 46 cm. The lower slip magnitudes are to the south at Withers Road, and the general trend is increased slip to the north, but there is more slip variability along the fault trace in the September 15 data. From August 26 to September 15, the west side of the fault trace uplifted between 0.5 and 5 cm relative to east side. Increased relief on the surface rupture itself indicated a slight compressional component of the deformation. These results confirm that post-event air photos can be useful for rapid 3D mapping, and that the unparalleled accuracy of TLS data can be used to quantify even very subtle deformation patterns in three dimensions and document changes through time.

Vortex dynamics in ruptured and unruptured intracranial aneurysms

NASA Astrophysics Data System (ADS)

Trylesinski, Gabriel

Intracranial aneurysms (IAs) are a potentially devastating pathological dilation of brain arteries that affect 1.5-5 % of the population. Causing around 500 000 deaths per year worldwide, their detection and treatment to prevent rupture is critical. Multiple recent studies have tried to find a hemodynamics predictor of aneurysm rupture, but concluded with distinct opposite trends using Wall Shear Stress (WSS) based parameters in different clinical datasets. Nevertheless, several research groups tend to converge for now on the fact that the flow patterns and flow dynamics of the ruptured aneurysms are complex and unstable. Following this idea, we investigated the vortex properties of both unruptured and ruptured cerebral aneurysms. A brief comparison of two Eulerian vortex visualization methods (Q-criterion and lambda 2 method) showed that these approaches gave similar results in our complex aneurysm geometries. We were then able to apply either one of them to a large dataset of 74 patient specific cases of intracranial aneurysms. Those real cases were obtained by 3D angiography, numerical reconstruction of the geometry, and then pulsatile CFD simulation before post-processing with the mentioned vortex visualization tools. First we tested the two Eulerian methods on a few cases to verify their implementation we made as well as compare them with each other. After that, the Q-criterion was selected as method of choice for its more obvious physical meaning (it shows the balance between two characteristics of the flow, its swirling and deformation). Using iso-surfaces of Q, we started by categorizing the patient-specific aneurysms based on the gross topology of the aneurysmal vortices. This approach being unfruitful, we found a new vortex-based characteristic property of ruptured aneurysms to stratify the rupture risk of IAs that we called the Wall-Kissing Vortices, or WKV. We observed that most ruptured aneurysms had a large amount of WKV, which appears to agree with the current hypothesized biological triggers of pathological remodeling of the artery walls. Having a good natural ratio of statuses in our IA cohort (55 unruptured vs. 19 ruptured), we were able to test the statistical significance of our predictor to fortify our findings. We also performed a distribution analysis of our cohort with respect to the number of WKV to strengthen the encouraging statistical analysis result; both analyses provided a clear good separation of the status of the aneurysms based on our predictor. Lastly, we constructed a receiver operating characteristic (ROC) curve to analyze the power different thresholds of WKV had in splitting the data in a binary way (unruptured/ruptured). The number of WKV was efficaciously able to stratify the rupture status, identifying 84.21 % of the ruptured aneurysms (with 25.45 % of false positives, i.e. unruptured IAs tagged as ruptured) when using a threshold value of 2. Our novel work undertaken to study the vortex structures in IAs brought to light interesting characteristics of the flow in the aneurysmal sac. We found that there are several distinct categories in which the aneurysm vortex topologies can be put in without relationship to the aneurysm rupture status. This first finding was in contradiction with available already-published results. Nonetheless, ruptured IAs had a statistically significant larger amount of WKV as opposed to unruptured aneurysms. This new predictor we propose to the community could very well clear a new path among the currently controversial WSS-based parameters. Although it needs to be improved to be more resilient, the first results obtained by the WKV-based parameter are promising when applied to a large dataset of 74 IAs patient-specific transient CFD simulations.

Simulation model of an eyeball based on finite element analysis on a supercomputer.

PubMed

Uchio, E; Ohno, S; Kudoh, J; Aoki, K; Kisielewicz, L T

1999-10-01

A simulation model of the human eye was developed. It was applied to the determination of the physical and mechanical conditions of impacting foreign bodies causing intraocular foreign body (IOFB) injuries. Modules of the Hypermesh (Altair Engineering, Tokyo, Japan) were used for solid modelling, geometric construction, and finite element mesh creation based on information obtained from cadaver eyes. The simulations were solved by a supercomputer using the finite element analysis (FEA) program PAM-CRASH (Nihon ESI, Tokyo, Japan). It was assumed that rupture occurs at a strain of 18.0% in the cornea and 6.8% in the sclera and at a stress of 9.4 MPa for both cornea and sclera. Blunt-shaped missiles were shot and set to impact on the surface of the cornea or sclera at velocities of 30 and 60 m/s, respectively. According to the simulation, the sizes of missile above which corneal rupture occurred at velocities of 30 and 60 m/s were 1.95 and 0.82 mm. The missile sizes causing scleral rupture were 0.95 and 0.75 mm at velocities of 30 and 60 m/s. These results suggest that this FEA model has potential usefulness as a simulation tool for ocular injury and it may provide useful information for developing protective measures against industrial and traffic ocular injuries.

Three-Dimensional Dynamic Rupture in Brittle Solids and the Volumetric Strain Criterion

NASA Astrophysics Data System (ADS)

Uenishi, K.; Yamachi, H.

2017-12-01

As pointed out by Uenishi (2016 AGU Fall Meeting), source dynamics of ordinary earthquakes is often studied in the framework of 3D rupture in brittle solids but our knowledge of mechanics of actual 3D rupture is limited. Typically, criteria derived from 1D frictional observations of sliding materials or post-failure behavior of solids are applied in seismic simulations, and although mode-I cracks are frequently encountered in earthquake-induced ground failures, rupture in tension is in most cases ignored. Even when it is included in analyses, the classical maximum principal tensile stress rupture criterion is repeatedly used. Our recent basic experiments of dynamic rupture of spherical or cylindrical monolithic brittle solids by applying high-voltage electric discharge impulses or impact loads have indicated generation of surprisingly simple and often flat rupture surfaces in 3D specimens even without the initial existence of planes of weakness. However, at the same time, the snapshots taken by a high-speed digital video camera have shown rather complicated histories of rupture development in these 3D solid materials, which seem to be difficult to be explained by, for example, the maximum principal stress criterion. Instead, a (tensile) volumetric strain criterion where the volumetric strain (dilatation or the first invariant of the strain tensor) is a decisive parameter for rupture seems more effective in computationally reproducing the multi-directionally propagating waves and rupture. In this study, we try to show the connection between this volumetric strain criterion and other classical rupture criteria or physical parameters employed in continuum mechanics, and indicate that the criterion has, to some degree, physical meanings. First, we mathematically illustrate that the criterion is equivalent to a criterion based on the mean normal stress, a crucial parameter in plasticity. Then, we mention the relation between the volumetric strain criterion and the failure envelope of the Mohr-Coulomb criterion that describes shear-related rupture. The critical value of the volumetric strain for rupture may be controlled by the apparent cohesion and apparent angle of internal friction of the Mohr-Coulomb criterion.

Rupturing Giant Plasma Membrane Vesicles to Form Micron-sized Supported Cell Plasma Membranes with Native Transmembrane Proteins.

PubMed

Chiang, Po-Chieh; Tanady, Kevin; Huang, Ling-Ting; Chao, Ling

2017-11-09

Being able to directly obtain micron-sized cell blebs, giant plasma membrane vesicles (GPMVs), with native membrane proteins and deposit them on a planar support to form supported plasma membranes could allow the membrane proteins to be studied by various surface analytical tools in native-like bilayer environments. However, GPMVs do not easily rupture on conventional supports because of their high protein and cholesterol contents. Here, we demonstrate the possibility of using compression generated by the air-water interface to efficiently rupture GPMVs to form micron-sized supported membranes with native plasma membrane proteins. We demonstrated that not only lipid but also a native transmembrane protein in HeLa cells, Aquaporin 3 (AQP3), is mobile in the supported membrane platform. This convenient method for generating micron-sized supported membrane patches with mobile native transmembrane proteins could not only facilitate the study of membrane proteins by surface analytical tools, but could also enable us to use native membrane proteins for bio-sensing applications.

Strain Measurement during Stress Rupture of Composite Over-Wrapped Pressure Vessel with Fiber Bragg Gratings Sensors

NASA Technical Reports Server (NTRS)

Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

2008-01-01

Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPV). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPY liner.

Rupture of vertical soap films

NASA Astrophysics Data System (ADS)

Rio, Emmanuelle

2014-11-01

Soap films are ephemeral and fragile objects. They tend to thin under gravity, which gives rise to the fascinating variations of colors at their interfaces but leads systematically to rupture. Even a child can create, manipulate and admire soap films and bubbles. Nevertheless, the reason why it suddenly bursts remains a mystery although the soap chosen to stabilize the film as well as the humidity of the air seem very important. One difficulty to study the rupture of vertical soap films is to control the initial solution. To avoid this problem we choose to study the rupture during the generation of the film at a controlled velocity. We have built an experiment, in which we measure the maximum length of the film together with its lifetime. The generation of the film is due to the presence of a gradient of surface concentration of surfactants at the liquid/air interface. This leads to a Marangoni force directed toward the top of the film. The film is expected to burst only when its weight is not balanced anymore by this force. We will show that this leads to the surprising result that the thicker films have shorter lifetimes than the thinner ones. It is thus the ability of the interface to sustain a surface concentration gradient of surfactants which controls its stability.

Effect of thermal pressurization on dynamic rupture propagation under depth-dependent stress

NASA Astrophysics Data System (ADS)

Urata, Y.; Kuge, K.; Kase, Y.

2009-12-01

Fluid and pore pressure evolution can affect dynamic propagation of earthquake ruptures owing to thermal pressurization (e.g., Mase and Smith, 1985). We investigate dynamic rupture propagation with thermal pressurization on a fault subjected to depth-dependent stress, on the basis of 3-D numerical simulations for spontaneous dynamic ruptures. We put a vertical strike-slip rectangular fault in a semi-infinite, homogenous, and elastic medium. The length and width of the fault are 8 and 3 km, respectively. We assume a depth-dependent stress estimated by Yamashita et al. (2004). The numerical algorithm is based on the finite-difference method by Kase and Kuge (2001). A rupture is initiated by increasing shear stress in a small patch at the bottom of the fault, and then proceeds spontaneously, governed by a slip-weakening law with the Coulomb failure criteria. Coefficients of friction and Dc are homogeneous on the fault. On a fault with thermal pressurization, we allow effective normal stress to vary with pore pressure change due to frictional heating by the formulation of Bizzarri and Cocco (2006). When thermal pressurization does not work, tractions drop in the same way everywhere and rupture velocity is subshear except near the free surface. Due to thermal pressurization, dynamic friction on the fault decreases and is heterogeneous not only vertically but horizontally, slip increases, and rupture velocity along the strike direction becomes supershear. As a result, plural peaks of final slip appear, as observed in the case of undrained dip-slip fault by Urata et al. (2008). We found in this study that the early stage of rupture growth under the depth-dependent stress is affected by the location of an initial crack. When a rupture is initiated at the center of the fault without thermal pressurization, the rupture cannot propagate and terminates. Thermal pressurization can help such a powerless rupture to keep propagating.

Investigation of Stainless Steel Corrosion in Ultrahigh-Purity Water and Steam Systems by Surface Analytical Techniques

NASA Astrophysics Data System (ADS)

Dong, Xia; Iacocca, Ronald G.; Bustard, Bethany L.; Kemp, Craig A. J.

2010-02-01

Stainless steel pipes with different degrees of rouging and a Teflon®-coated rupture disc with severe corrosion were thoroughly investigated by combining multiple surface analytical techniques. The surface roughness and iron oxide layer thickness increase with increasing rouge severity, and the chromium oxide layer coexists with the iron oxide layer in samples with various degrees of rouging. Unlike the rouging observed for stainless steel pipes, the fast degradation of the rupture disc was caused by a crevice corrosion environment created by perforations in the protective Teflon coating. This failure analysis clearly shows the highly corrosive nature of ultrapure water used in the manufacture of pharmaceutical products, and demonstrates some of the unexpected corrosion mechanisms that can be encountered in these environments.

Co-seismic strike-slip surface rupture and displacement produced by the 2010 Mw 6.9 Yushu earthquake, China, and implications for Tibetan tectonics

NASA Astrophysics Data System (ADS)

Lin, A.; Rao, G.; Jia, D.; Wu, X.; Yan, B.; Ren, Z.

2010-12-01

The magnitude (Mw) 6.9 (Ms 7.1) Yushu earthquake occurred on 14 April 2010 in the Yushu area, central Tibetan Plateau, killing approximately 3000 people (including 270 missing) and causing widespread damage in the high mountain regions of the central Tibetan Plateau. The Yushu earthquake is comparable with the 1997 Mw 7.6 Manyi earthquake, the 2001 Mw 7.8 Kunlun earthquake, and the 2008 Mw 7.9 Wenchuan earthquake, which all occurred in the northern and eastern Tibetan Plateau, in terms of their magnitude and seismotectonic environment, related to the eastward extrusion of the Tibetan Plateau in response to continental collision between the Indian and Eurasian plates. Although some prompt reports related to ground deformation and the focal mechanism were published in the Chinese literature soon after the Yushu earthquake, there are scarce data related to the nature of co-seismic strike-slip rupturing structures and displacement distributions because the co-seismic surface ruptures were produced mainly in remote, high mountain regions of the Tibetan Plateau (average elevation >4000 m) and roads to the epicentral area were damaged, which made it difficult to gain access to the area and to undertake fieldwork immediately after the earthquake. Field investigations reveal that the earthquake produced a 33-km-long surface rupture zone, with dominantly left-lateral strike-slip along the Yushu Fault of the pre-existing strike-slip Ganzi-Yushu Fault Zone. The co-seismic surface ruptures are characterized by discontinuous shear faults, right-stepping en echelon tensional cracks, and left-stepping mole track structures that indicate a left-lateral strike-slip shear sense for the seismic fault. Field measurements indicate co-seismic left-lateral strike-slip displacements of approximately 0.3-3.2 m (typically 1-2 m), accompanied by a minor vertical component of <0.6 m. The present results show that (i) the Yushu earthquake occurred upon the pre-existing active Ganzi-Yushu Fault Zone, which controlled the spatial distribution of co-seismic surface ruptures and displacements; (ii) the left-lateral strike-slip motion indicates that the Ganzi-Yushu Fault Zone partitions deformation into eastward extrusion and northeastward shortening of the central Tibetan Plateau to accommodate the continuing penetration of the Indian plate into the Eurasian plate. Our findings confirm that present-day strain energy related to continental deformation in the central Tibetan Plateau, generated by collision between the Indian and Eurasian plates, is mainly released by strike-slip faulting along active strike-slip faults, and that the Ganzi-Yushu Fault Zone plays an important role in this crustal deformation, generating strong earthquakes that help to release the accumulated strain energy.

Imaging Complex Fault Slip of the 2016 MeiNong and Kumamoto Earthquakes with Sentinel-1 InSAR and Other Geodetic and Seismic Data

NASA Astrophysics Data System (ADS)

Fielding, E. J.; Huang, M. H.; Liang, C.; Yue, H.; Agram, P. S.; Simons, M.; Fattahi, H.; Tung, H.; Hu, J. C.; Huang, C.

2016-12-01

We map complex fault ruptures of the February 2016 MeiNong earthquake in Taiwan and the April 2016 Kumamoto earthquake sequence in Japan by analysis of Synthetic Aperture Radar (SAR) data from the Copernicus Sentinel-1A (S1A) satellite operated by the European Space Agency and the Advanced Land Observation Satellite-2 (ALOS-2) satellite operated by the Japanese Aerospace Exploration Agency (JAXA). Our analysis shows that the MeiNong main rupture at lower crustal depth triggered slip on another fault at upper crustal depth and shallow slip on several faults in the upper few km. The Kumamoto earthquake sequence ruptured two major fault systems over two days and triggered shallow slip on a large number of shallow faults. We combine less precise analysis of large scale displacements from the SAR images of the two satellites by pixel offset tracking or sub-pixel correlation, including the along-track component of surface motion, with the more precise SAR interferometry (InSAR) measurements in the radar line-of-sight direction to estimate all three components of the surface displacement for the events. Data was processed with customized workflows based on modules in the InSAR Scientific Computing Environment (ISCE). Joint inversion of S1A and ALOS-2 InSAR, GPS, and strong motion seismograms for the Mw6.4 MeiNong earthquake shows that the main thrust rupture with N61°W strike and 15° dip at 15-20 km depth explains nearly all of the seismic waveforms but leaves a substantial uplift residual in the InSAR and GPS offsets estimated 4 hours after the earthquake. We model this residual with slip on a N8°E-trending thrust fault dipping 30° at depths between 5-10 km. This fault strike is parallel to surface faults and we interpret it as fault slip within a mid-crustal duplex that was triggered by the main rupture within 4 hours of the mainshock. In addition, InSAR shows sharp discontinuities at many locations that are likely due to shallow triggered slip, but the timing of these is uncertain. The Kumamoto earthquake sequence in Japan started with Mw 6.2 and 6.0 earthquakes on 14 April (UTC) followed on 15 April by the Mw 7.0 mainshock. JAXA acquired one ALOS-2 scene between the foreshocks and mainshock that enables some separation of the surface deformation. InSAR shows M6 foreshocks were deeper, while M7 mainshock ruptured surface in many places.

Horizontal surface-slip distribution through several seismic cycles: The Eastern Bogd fault, Gobi-Altai, Mongolia

NASA Astrophysics Data System (ADS)

Kurtz, R.; Klinger, Y.; Ferry, M.; Ritz, J.-F.

2018-06-01

The 1957, MW 8.1, Gobi-Altai earthquake, Southern Mongolia, produced a 360-km-long surface rupture along the Eastern Bogd fault. Cumulative offsets of geomorphic features suggest that the Eastern Bogd fault might produce characteristic slip over the last seismic cycles. Using orthophotographs derived from a dataset of historical aerial photographs acquired in 1958, we measured horizontal offsets along two thirds ( 170 km) of the 1957 left-lateral strike-slip surface rupture. We propose a new empirical methodology to extract the average slip for each past earthquake that could be recognized along successive fault segments, to determine the slip distribution associated with successive past earthquakes. Our results suggest that the horizontal slip distribution of the 1957 Gobi-Altai earthquake is fairly flat, with an average offset of 3.5 m ± 1.3 m. A combination of our lateral measurements with vertical displacements derived from the literature, allows us to re-assess the magnitude of the Gobi-Altai earthquake to be between MW 7.8 and MW 8.2, depending on the depth of the rupture, and related value of the shear modulus. When comparing this magnitude to magnitudes derived from seismic data, it suggests that the rupture may have extended deeper than the 15 km to 20 km usually considered for the seismogenic crust. We observe that some fault segments are more likely than others to record seismic deformation through several seismic cycles, depending on the local rupture complexity and geomorphology. Additionally, our results allow us to model the horizontal slip function for the 1957 Gobi-Altai earthquake and for three previous paleoseismic events along 70% of the studied area. Along about 50% of the fault sections where we could recognize three past earthquakes, our results suggest that the slip per event was similar for each earthquake.

Magnitude and Surface Rupture Length of Prehistoric Upper Crustal Earthquakes in the Puget Lowland, Washington State

NASA Astrophysics Data System (ADS)

Sherrod, B. L.; Styron, R. H.

2016-12-01

Paleoseismic studies documented prehistoric earthquakes after the last glaciation ended 15 ka on 13 upper-crustal fault zones in the Cascadia fore arc. These fault zones are a consequence of north-directed fore arc block migration manifesting as a series of bedrock uplifts and intervening structural basins in the southern Salish Sea lowland between Vancouver, B.C. to the north and Olympia, WA to the south, and bounded on the east and west by the Cascade Mountains and Olympic Mountains, respectively. Our dataset uses published information and includes 27 earthquakes tabulated from observations of postglacial deformation at 63 sites. Stratigraphic offsets along faults consist of two types of measurements: 1) vertical separation of strata along faults observed in fault scarp excavations, and 2) estimates from coastal uplift and subsidence. We used probabilistic methods to estimate past rupture magnitudes and surface rupture length (SRL), applying empirical observations from modern earthquakes and point measurements from paleoseismic sites (Biasi and Weldon, 2006). Estimates of paleoearthquake magnitude ranged between M 6.5 and M 7.5. SRL estimates varied between 20 and 90 km. Paleoearthquakes on the Seattle fault zone and Saddle Mountain West fault about 1100 years ago were outliers in our analysis. Large offsets observed for these two earthquakes implies a M 7.8 and 200 km SRL, given the average observed ratio of slip/SRL in modern earthquakes. The actual mapped traces of these faults are less than 200km, implying these earthquakes had an unusually high static stress drop or, in the case of the Seattle fault, splay faults may have accentuated uplift in the hanging wall. Refined calculations incorporating fault area may change these magnitude and SRL estimates. Biasi, G.P., and Weldon, R.J., 2006, Estimating Surface Rupture Length and Magnitude of Paleoearthquakes from Point Measurements of Rupture Displacement: B. Seismol. Soc. Am., 96, 1612-1623.

LiDAR and field observations of slip distribution for the most recent surface ruptures along the central San Jacinto fault

USGS Publications Warehouse

J.B. Salisbury,; T.K. Rockwell,; T.J. Middleton,; Hudnut, Kenneth W.

2012-01-01

We measured offsets on tectonically displaced geomorphic features along 80 km of the Clark strand of the San Jacinto fault (SJF) to estimate slip‐per‐event for the past several surface ruptures. We identify 168 offset features from which we make over 490 measurements using B4 light detection and ranging (LiDAR) imagery and field observations. Our results suggest that LiDAR technology is an exemplary supplement to traditional field methods in slip‐per‐event studies. Displacement estimates indicate that the most recent surface‐rupturing event (MRE) produced an average of 2.5–2.9 m of right‐lateral slip with maximum slip of nearly 4 m at Anza, a Mw 7.2–7.5 earthquake. Average multiple‐event offsets for the same 80 kms are ∼5.5  m, with maximum values of 3 m at Anza for the penultimate event. Cumulative displacements of 9–10 m through Anza suggest the third event was also similar in size. Paleoseismic work at Hog Lake dates the most recent surface rupture event at ca. 1790. A poorly located, large earthquake occurred in southern California on 22 November 1800; we relocate this event to the Clark fault based on the MRE at Hog Lake. We also recognize the occurrence of a younger rupture along ∼15–20  km of the fault in Blackburn Canyon with ∼1.25  m of average displacement. We attribute these offsets to the 21 April 1918 Mw 6.9 event. These data argue that much or all of the Clark fault, and possibly also the Casa Loma fault, fail together in large earthquakes, but that shorter sections may fail in smaller events.

Stress triggering of the 1999 Hector Mine earthquake by transient deformation following the 1992 Landers earthquake

USGS Publications Warehouse

Pollitz, F.F.; Sacks, I.S.

2002-01-01

The M 7.3 June 28, 1992 Landers and M 7.1 October 16, 1999 Hector Mine earthquakes, California, both right lateral strike-slip events on NNW-trending subvertical faults, occurred in close proximity in space and time in a region where recurrence times for surface-rupturing earthquakes are thousands of years. This suggests a causal role for the Landers earthquake in triggering the Hector Mine earthquake. Previous modeling of the static stress change associated with the Landers earthquake shows that the area of peak Hector Mine slip lies where the Coulomb failure stress promoting right-lateral strike-slip failure was high, but the nucleation point of the Hector Mine rupture was neutrally to weakly promoted, depending on the assumed coefficient of friction. Possible explanations that could account for the 7-year delay between the two ruptures include background tectonic stressing, dissipation of fluid pressure gradients, rate- and state-dependent friction effects, and post-Landers viscoelastic relaxation of the lower crust and upper mantle. By employing a viscoelastic model calibrated by geodetic data collected during the time period between the Landers and Hector Mine events, we calculate that postseismic relaxation produced a transient increase in Coulomb failure stress of about 0.7 bars on the impending Hector Mine rupture surface. The increase is greatest over the broad surface that includes the 1999 nucleation point and the site of peak slip further north. Since stress changes of magnitude greater than or equal to 0.1 bar are associated with documented causal fault interactions elsewhere, viscoelastic relaxation likely contributed to the triggering of the Hector Mine earthquake. This interpretation relies on the assumption that the faults occupying the central Mojave Desert (i.e., both the Landers and Hector Mine rupturing faults) were critically stressed just prior to the Landers earthquake.

Rupture parameters of the 2003 Zemmouri (Mw 6.8), Algeria, earthquake from joint inversion of interferometric synthetic aperture radar, coastal uplift, and GPS

USGS Publications Warehouse

Belabbes, S.; Wicks, Charles; Cakir, Z.; Meghraoui, M.

2009-01-01

We study the surface deformation associated with the 21 May 2003 (M w = 6.8) Zemmouri (Algeria) earthquake, the strongest seismic event felt in the Algiers region since 1716. The thrust earthquake mechanism and related surface deformation revealed an average 0.50 m coastal uplift along ??55-km-long coastline. We obtain coseismic interferograms using Envisat advanced synthetic aperture radar (ASAR) (IS2) and RADARSAT standard beam (ST4) data from both the ascending and descending orbits of Envisat satellite, whereas the RADARSAT data proved useful only in the descending mode. While the two RADARSAT interferograms cover the earthquake area, Envisat data cover only the western half of the rupture zone. Although the interferometric synthetic aperture radar (InSAR) coherence in the epicenter area is poor, deformation fringes are observed along the coast in different patches. In the Boumerdes area, the maximum coseismic deformation is indicated by the high gradient of fringes visible in all interferograms in agreement with field measurements (tape, differential GPS, leveling, and GPS). To constrain the earthquake rupture parameters, we model the interferograms and uplift measurements using elastic dislocations on triangular fault patches in an elastic and homogeneous half-space. We invert the coseismic slip using first, a planar surface and second, a curved fault, both constructed from triangular elements using Poly3Dinv program that uses a damped least square minimization. The best fit of InSAR, coastal uplift, and GPS data corresponds to a 65-km-long fault rupture dipping 40?? to 50?? SE, located at 8 to 13 km offshore with a change in strike west of Boumerdes from N60??-65?? to N95??-105??. The inferred rupture geometry at depth correlates well with the seismological results and may have critical implications for the seismic hazard assessment of the Algiers region. Copyright 2009 by the American Geophysical Union.

The Bear River Fault Zone, Wyoming and Utah: Complex Ruptures on a Young Normal Fault

NASA Astrophysics Data System (ADS)

Schwartz, D. P.; Hecker, S.; Haproff, P.; Beukelman, G.; Erickson, B.

2012-12-01

The Bear River fault zone (BRFZ), a set of normal fault scarps located in the Rocky Mountains at the eastern margin of Basin and Range extension, is a rare example of a nascent surface-rupturing fault. Paleoseismic investigations (West, 1994; this study) indicate that the entire neotectonic history of the BRFZ may consist of two large surface-faulting events in the late Holocene. We have estimated a maximum per-event vertical displacement of 6-6.5 m at the south end of the fault where it abuts the north flank of the east-west-trending Uinta Mountains. However, large hanging-wall depressions resulting from back rotation, which front scarps that locally exceed 15 m in height, are prevalent along the main trace, obscuring the net displacement and its along-strike distribution. The modest length (~35 km) of the BRFZ indicates ruptures with a large displacement-to-length ratio, which implies earthquakes with a high static stress drop. The BRFZ is one of several immature (low cumulative displacement) normal faults in the Rocky Mountain region that appear to produce high-stress drop earthquakes. West (1992) interpreted the BRFZ as an extensionally reactivated ramp of the late Cretaceous-early Tertiary Hogsback thrust. LiDAR data on the southern section of the fault and Google Earth imagery show that these young ruptures are more extensive than currently mapped, with newly identified large (>10m) antithetic scarps and footwall graben. The scarps of the BRFZ extend across a 2.5-5.0 km-wide zone, making this the widest and most complex Holocene surface rupture in the Intermountain West. The broad distribution of Late Holocene scarps is consistent with reactivation of shallow bedrock structures but the overall geometry of the BRFZ at depth and its extent into the seismogenic zone are uncertain.

Rupture threshold characterization of polymer-shelled ultrasound contrast agents subjected to static overpressure

NASA Astrophysics Data System (ADS)

Chitnis, Parag V.; Lee, Paul; Mamou, Jonathan; Allen, John S.; Böhmer, Marcel; Ketterling, Jeffrey A.

2011-04-01

Polymer-shelled micro-bubbles are employed as ultrasound contrast agents (UCAs) and vesicles for targeted drug delivery. UCA-based delivery of the therapeutic payload relies on ultrasound-induced shell rupture. The fragility of two polymer-shelled UCAs manufactured by Point Biomedical or Philips Research was investigated by characterizing their response to static overpressure. The nominal diameters of Point and Philips UCAs were 3 μm and 2 μm, respectively. The UCAs were subjected to static overpressure in a glycerol-filled test chamber with a microscope-reticule lid. UCAs were reconstituted in 0.1 mL of water and added over the glycerol surface in contact with the reticule. A video-microscope imaged UCAs as glycerol was injected (5 mL/h) to vary the pressure from 2 to 180 kPa over 1 h. Neither UCA population responded to overpressure until the rupture threshold was exceeded, which resulted in abrupt destruction. The rupture data for both UCAs indicated three subclasses that exhibited different rupture behavior, although their mean diameters were not statistically different. The rupture pressures provided a measure of UCA fragility; the Philips UCAs were more resilient than Point UCAs. Results were compared to theoretical models of spherical shells under compression. Observed variations in rupture pressures are attributed to shell imperfections. These results may provide means to optimize polymeric UCAs for drug delivery and elucidate associated mechanisms.

Sonographic findings of ruptured epidermal inclusion cysts in superficial soft tissue: emphasis on shapes, pericystic changes, and pericystic vascularity.

PubMed

Jin, Wook; Ryu, Kyung Nam; Kim, Gou Young; Kim, Hyun Cheol; Lee, Jae Hoon; Park, Ji Seon

2008-02-01

The purpose of this study was to retrospectively evaluate the sonographic findings of ruptured epidermal inclusion cysts in superficial soft tissue, with an emphasis on shapes, pericystic changes, and pericystic vascularity. The cases of 61 patients with surgically confirmed epidermal inclusion cysts were reviewed, and 13 patients were found to have ruptured cysts. The Ethics Committees of our institutions did not require patient approval or informed patient consent for this retrospective study. We evaluated the shapes, sizes, locations, pericystic changes, and pericystic vascularity for the 13 cases. The shapes of the ruptured epidermal inclusion cysts were classified into 3 types: with lobulations (type I, 2 cases), with protrusions (type II, 8 cases), and with abscess pocket formations (type III, 3 cases). The mean long diameter of the cysts was 3 cm. Common sites of ruptured epidermal inclusion cysts were the plantar surface of the metatarsophalangeal joint (4 cases) and buttocks (3 cases). Pericystic changes were noted in all of the type II and III cysts. Increased vascularity on color Doppler sonography was prominent in 3 type II cysts and 3 type III cysts. Deep abscess formation was noted in the epidermal inclusion cysts, especially for the type III cysts. A ruptured epidermal inclusion cyst visualized by sonography had variable shapes; the sonographic findings can be useful for obtaining a correct diagnosis of a ruptured epidermal inclusion cyst.

Magnetic resonance imaging of breast implants.

PubMed

Shah, Mala; Tanna, Neil; Margolies, Laurie

2014-12-01

Silicone breast implants have significantly evolved since their introduction half a century ago, yet implant rupture remains a common and expected complication, especially in patients with earlier-generation implants. Magnetic resonance imaging is the primary modality for assessing the integrity of silicone implants and has excellent sensitivity and specificity, and the Food and Drug Administration currently recommends periodic magnetic resonance imaging screening for silent silicone breast implant rupture. Familiarity with the types of silicone implants and potential complications is essential for the radiologist. Signs of intracapsular rupture include the noose, droplet, subcapsular line, and linguine signs. Signs of extracapsular rupture include herniation of silicone with a capsular defect and extruded silicone material. Specific sequences including water and silicone suppression are essential for distinguishing rupture from other pathologies and artifacts. Magnetic resonance imaging provides valuable information about the integrity of silicone implants and associated complications.

Great paleoearthquakes of the central Himalaya and their implications for seismotectonic models and seismic hazard assessment

NASA Astrophysics Data System (ADS)

Yule, D.; Lave, J.; Kumar, S.; Wesnousky, S.

2007-12-01

A growing body of paleoseismic data collected from more than ten sites in Nepal and India has documented large coseismic displacements at the thrust front (Main Frontal thrust (MFT)). Three great earthquakes have been identified: in ~A.D. 1410 centered north of Delhi, in A.D. 1505 centered in far-western Nepal, and in ~A.D. 1100 centered in eastern Nepal. It is noteworthy that wherever exposures of the MFT have been studied estimates of surface slip are consistently large; with a range of 9-26 m. Historic accounts of the 1505 earthquake describe strong shaking across a 600-km-long stretch of the central Himalaya. A magnitude for this event is estimated to be >Mw 8.5 based on the maximum extent of felt strong shaking, the 100 km width of the locked portion of the basal detachment, and an average slip of 10-15 m. Though no historic accounts exist for the ~1410 and ~1100 earthquakes, the similarity between their surface expression and the 1505 rupture suggests that these events may have been equally large. These surface-rupturing earthquakes are distinctly different from a host of blind thrust events (Mw 7.5-8.4) that dominate the historic record since A.D. 1505. Both blind and emergent earthquakes are presumed to rupture the basal detachment and release interseismic strain that accumulates near the base of the High Himalaya and carry it to the thrust front where Holocene shortening occurs at rates of 15-22 mm/yr. Whereas the surface-rupturing earthquakes clearly deform the thrust front, survey data from the region affected by the 1906 Dehra Dun earthquake suggest that blind events contribute negligible, if any, deformation to the frontal structures. The factors controlling whether or not surface rupture occurs on the MFT remain unconstrained, but the current data seem to suggest that >Mw 8.5 surface-rutpuring earthquakes are the primary contributors to the shortening observed at the thrust front. It is sobering to consider that the 'Big One' has not struck the Himalaya in over 500 years and that Mw 7.5-8.4 earthquakes are the 'moderate' earthquakes'. Further study to constrain the lateral extent and recurrence of the great paleoearthquakes of the central Himalaya is critical to answer important questions about the Himalaya earthquake cycle and the seismic hazard facing the rapidly urbanizing population of the region.

Creep, creep-rupture tests of Al-surface-alloyed T91 steel in liquid lead bismuth at 500 and 550 °C

NASA Astrophysics Data System (ADS)

Weisenburger, A.; Jianu, A.; An, W.; Fetzer, R.; Del Giacco, Mattia; Heinzel, A.; Müller, G.; Markov, V. G.; Kasthanov, A. D.

2012-12-01

Surface layers made of FeCrAl alloys on T91 steel have shown their capability as corrosion protection barriers in lead bismuth. Pulsed electron beam treatment improves the density and more over the adherence of such layers. After the treatment of previously deposited coatings a surface graded material is achieved with a metallic bonded interface. Creep-rupture tests of T91 in lead-alloy at 550 °C reveal significant reduced creep strength of non-modified T91 test specimens. Oxide scales protecting the steels from attacks of the liquid metal will crack at a certain strain leading to a direct contact between the steel and the liquid metal. The negative influence of the lead-alloy on the creep behavior of non-modified T91 is stress dependent, but below a threshold stress value of 120 MPa at 550 °C this influence becomes almost negligible. At 500 °C and stress values of 200 MPa and 220 MPa the creep rates are comparable between them and significantly lower than creep rates at 180 MPa of original T91 in air at 550 °C. No signs of LBE influence are detected. The surface modified specimens tested at high stress levels instead had creep-rupture times similar to T91 (original state) tested in air. The thin oxide layers formed on the surface modified steel samples are less susceptible to crack formation and therefore to lead-alloy enhanced creep.

New constraints on the rupture process of the 1999 August 17 Izmit earthquake deduced from estimates of stress glut rate moments

NASA Astrophysics Data System (ADS)

Clévédé, E.; Bouin, M.-P.; Bukchin, B.; Mostinskiy, A.; Patau, G.

2004-12-01

This paper illustrates the use of integral estimates given by the stress glut rate moments of total degree 2 for constraining the rupture scenario of a large earthquake in the particular case of the 1999 Izmit mainshock. We determine the integral estimates of the geometry, source duration and rupture propagation given by the stress glut rate moments of total degree 2 by inverting long-period surface wave (LPSW) amplitude spectra. Kinematic and static models of the Izmit earthquake published in the literature are quite different from one another. In order to extract the characteristic features of this event, we calculate the same integral estimates directly from those models and compare them with those deduced from our inversion. While the equivalent rupture zone and the eastward directivity are consistent among all models, the LPSW solution displays a strong unilateral character of the rupture associated with a short rupture duration that is not compatible with the solutions deduced from the published models. With the aim of understand this discrepancy, we use simple equivalent kinematic models to reproduce the integral estimates of the considered rupture processes (including ours) by adjusting a few free parameters controlling the western and eastern parts of the rupture. We show that the joint analysis of the LPSW solution and source tomographies allows us to elucidate the scattering of source processes published for this earthquake and to discriminate between the models. Our results strongly suggest that (1) there was significant moment released on the eastern segment of the activated fault system during the Izmit earthquake; (2) the apparent rupture velocity decreases on this segment.

A Benchmarking setup for Coupled Earthquake Cycle - Dynamic Rupture - Tsunami Simulations

NASA Astrophysics Data System (ADS)

Behrens, Joern; Bader, Michael; van Dinther, Ylona; Gabriel, Alice-Agnes; Madden, Elizabeth H.; Ulrich, Thomas; Uphoff, Carsten; Vater, Stefan; Wollherr, Stephanie; van Zelst, Iris

2017-04-01

We developed a simulation framework for coupled physics-based earthquake rupture generation with tsunami propagation and inundation on a simplified subduction zone system for the project "Advanced Simulation of Coupled Earthquake and Tsunami Events" (ASCETE, funded by the Volkswagen Foundation). Here, we present a benchmarking setup that can be used for complex rupture models. The workflow begins with a 2D seismo-thermo-mechanical earthquake cycle model representing long term deformation along a planar, shallowly dipping subduction zone interface. Slip instabilities that approximate earthquakes arise spontaneously along the subduction zone interface in this model. The absolute stress field and material properties for a single slip event are used as initial conditions for a dynamic earthquake rupture model.The rupture simulation is performed with SeisSol, which uses an ADER discontinuous Galerkin discretization scheme with an unstructured tetrahedral mesh. The seafloor displacements resulting from this rupture are transferred to the tsunami model with a simple coastal run-up profile. An adaptive mesh discretizing the shallow water equations with a Runge-Kutta discontinuous Galerkin (RKDG) scheme subsequently allows for an accurate and efficient representation of the tsunami evolution and inundation at the coast. This workflow allows for evaluation of how the rupture behavior affects the hydrodynamic wave propagation and coastal inundation. We present coupled results for differing earthquake scenarios. Examples include megathrust only ruptures versus ruptures with splay fault branching off the megathrust near the surface. Coupling to the tsunami simulation component is performed either dynamically (time dependent) or statically, resulting in differing tsunami wave and inundation behavior. The simplified topographical setup allows for systematic parameter studies and reproducible physical studies.

Stress-rupture strength and microstructural stability of tungsten-hafnium-carbon-wire reinforced superalloy composites

NASA Technical Reports Server (NTRS)

Petrasek, D. W.; Signorelli, R. A.

1974-01-01

Tungsten-hafnium-carbon - superalloy composites were found to be potentially useful for turbine blade applications on the basis of stress-rupture strength. The 100- and 1000-hr rupture strengths calculated for 70 vol. % fiber composites based on test data at 1090C (2000F) were 420 and 280 MN/m2 (61,000 and 41,000 psi, respectively). The investigation indicated that, with better quality fibers, composites having 100- and 1000-hr rupture strengths of 570 and 370 MN/m2 (82,000 and 54,000 psi, respectively), may be obtained. Metallographic studies indicated sufficient fiber-matrix compatibility for 1000 hr or more at 1090C (2000F).

Dynamics of a pre-lens tear film after a blink: Model, evolution, and rupture

NASA Astrophysics Data System (ADS)

Usha, R.; Anjalaiah, Sanyasiraju, Y. V. S. S.

2013-11-01

A mathematical model is developed to investigate the dynamics and rupture of a pre-lens tear film on a contact lens. The contact lens is modeled as a saturated porous medium of constant, finite thickness and is described by the Darcy-Brinkman equations with stress-jump condition at the interface. The model incorporates the influence of capillarity, gravitational drainage, contact lens properties such as the permeability, the porosity, and the thickness of the contact lens on the evolution and rupture of a pre-lens tear film, when the eyelid has opened after a blink. Two models are derived for the evolution of a pre-lens tear film thickness using lubrication theory and are solved numerically; the first uses shear-free surface condition and the second, the tangentially immobile free surface condition. The results reveal that life span of a pre-lens tear film is longer on a thinner contact lens for all values of permeability and porosity parameter considered. An increase in permeability of contact lens, porosity or stress-jump parameter increases the rate of thinning of the film and advances the rupture time. The viscous-viscous interaction between the porous contact lens and the pre-lens tear film increases the resistance offered by the frictional forces to the rate of thinning of pre-lens tear film. This slows down the thinning process and hence delays the rupture of the film as compared to that predicted by the models of Nong and Anderson [SIAM. J. Appl. Math. 70, 2771-2795 (2010)] derived in the framework of Darcy model.

Isolation and Characterization of Human Anterior Cruciate Ligament-Derived Vascular Stem Cells

PubMed Central

Matsumoto, Tomoyuki; Ingham, Sheila M.; Mifune, Yutaka; Osawa, Aki; Logar, Alison; Usas, Arvydas; Kuroda, Ryosuke; Kurosaka, Masahiro; Fu, Freddie H.

2012-01-01

The anterior cruciate ligament (ACL) usually fails to heal after rupture mainly due to the inability of the cells within the ACL tissue to establish an adequate healing process, making graft reconstruction surgery a necessity. However, some reports have shown that there is a healing potential of ACL with primary suture repair. Although some reports showed the existence of mesenchymal stem cell-like cells in human ACL tissues, their origin still remains unclear. Recently, blood vessels have been reported to represent a rich supply of stem/progenitor cells with a characteristic expression of CD34 and CD146. In this study, we attempted to validate the hypothesis that CD34- and CD146-expressing vascular cells exist in hACL tissues, have a potential for multi-lineage differentiation, and are recruited to the rupture site to participate in the intrinsic healing of injured ACL. Immunohistochemistry and flow cytometry analysis of hACL tissues demonstrated that it contains significantly more CD34 and CD146-positive cells in the ACL ruptured site compared with the noninjured midsubstance. CD34+CD45− cells isolated from ACL ruptured site showed higher expansionary potentials than CD146+CD45− and CD34−CD146−CD45− cells, and displayed higher differentiation potentials into osteogenic, adipogenic, and angiogenic lineages than the other cell populations. Immunohistochemistry of fetal and adult hACL tissues demonstrated a higher number of CD34 and CD146-positive cells in the ACL septum region compared with the midsubstance. In conclusion, our findings suggest that the ACL septum region contains a population of vascular-derived stem cells that may contribute to ligament regeneration and repair at the site of rupture. PMID:21732814

The Himalayan Seismogenic Zone: A New Frontier for Earthquake Research

NASA Astrophysics Data System (ADS)

Brown, Larry; Hubbard, Judith; Karplus, Marianne; Klemperer, Simon; Sato, Hiroshi

2016-04-01

The Mw 7.8 Gorkha, Nepal, earthquake that occurred on April 25 of this year was a dramatic reminder that great earthquakes are not restricted to the large seismogenic zones associated with subduction of oceanic lithosphere. Not only does Himalayan seismogenesis represents important scientific and societal issues in its own right, it constitutes a reference for evaluating general models of the earthquake cycle derived from the studies of the oceanic subduction systems. This presentation reports results of a Mini-Workshop sponsored by the GeoPrisms project that was held in conjunction with the American Geophysical Union on December 15, 2015, designed to organize a new initiative to study the great Himalaya earthquake machine. The Himalayan seismogenic zone shares with its oceanic counterparts a number of fundamental questions, including: a) What controls the updip and downdip limits of rupture? b) What controls the lateral segmentation of rupture zones (and hence magnitude)? c) What is the role of fluids in facilitating slip and or rupture? d) What nucleates rupture (e..g. asperities?)? e) What physical properties can be monitored as precursors to future events? f) How effectively can the radiation pattern of future events be modeled? g) How can a better understanding of Himalayan rupture be translated into more cost effective preparations for the next major event in this region? However the underthrusting of continental, as opposed to oceanic, lithosphere in the Himalayas frames these questions in a very different context: h) How does the greater thickness and weaker rheology of continental crust/lithosphere affect locking of the seismogenic zone? i) How does the different thermal structure of continental vs oceanic crust affect earthquake geodynamics? j) Are fluids a significant factor in intercontinental thrusting? k) How does the basement morphology of underthrust continental crust affect locking/creep, and how does it differ from the oceanic case? l) What is the significance of blind splay faulting in accommodating slip? m) Do lithologic contrasts juxtaposed across the continental seismogenic zone play a role in the rheological behavior of the SZ in the same manner as proposed for the ocean SZ? Major differences in the study of the continental vs oceanic seismogenic zone include the fact that Himalaya structures are open to: a) direct geological observation via field mapping b) dense and wide aperture monitoring of surface strain via GPS and INSAR c) extensive sampling of geofluids via surface flows and shallow drill holes d) cost effective deployment of long term geophysical arrays (e.g. seismic and MT) designed to detect subtle variations if physical properties within the seismogenic zone, and ultimately, e) a fixed platform for deep drilling of past and future rupture zones It remains to be established whether the Himalayan seismogenic zone has the potential for earthquakes of the greatest magnitudes (e.g. 9.0+). However, there is no question that future ruptures in this system represent a serious threat to major population centers (megacities) in the Indian subcontinent. For this reason alone the HSZ is deserving of a major new international, multidisciplinary effort.

Study on acoustic-electric-heat effect of coal and rock failure processes under uniaxial compression

NASA Astrophysics Data System (ADS)

Li, Zhong-Hui; Lou, Quan; Wang, En-Yuan; Liu, Shuai-Jie; Niu, Yue

2018-02-01

In recent years, coal and rock dynamic disasters are becoming more and more severe, which seriously threatens the safety of coal mining. It is necessary to carry out an depth study on the various geophysical precursor information in the process of coal and rock failure. In this paper, with the established acoustic-electric-heat multi-parameter experimental system of coal and rock, the acoustic emission (AE), surface potential and thermal infrared radiation (TIR) signals were tested and analyzed in the failure processes of coal and rock under the uniaxial compression. The results show that: (1) AE, surface potential and TIR have different response characteristics to the failure process of the sample. AE and surface potential signals have the obvious responses to the occurrence, extension and coalescence of cracks. The abnormal TIR signals occur at the peak and valley points of the TIR temperature curve, and are coincident with the abnormities of AE and surface potential to a certain extent. (2) The damage precursor points and the critical precursor points were defined to analyze the precursor characteristics reflected by AE, surface potential and TIR signals, and the different signals have the different precursor characteristics. (3) The increment of the maximum TIR temperature after the main rupture of the sample is significantly higher than that of the average TIR temperature. Compared with the maximum TIR temperature, the average TIR temperature has significant hysteresis in reaching the first peak value after the main rapture. (4) The TIR temperature contour plots at different times well show the evolution process of the surface temperature field of the sample, and indicate that the sample failure originates from the local destruction.

Rapid Measurement of Tectonic Deformation Using Structure-from-Motion

NASA Astrophysics Data System (ADS)

Pickering, A.; DeLong, S.; Lienkaemper, J. J.; Hecker, S.; Prentice, C. S.; Schwartz, D. P.; Sickler, R. R.

2016-12-01

Rapid collection and distribution of accurate surface slip data after earthquakes can support emergency response, help coordinate scientific response, and constrain coseismic slip that can be rapidly overprinted by postseismic slip, or eliminated as evidence of surface deformation is repaired or obscured. Analysis of earthquake deformation can be achieved quickly, repeatedly and inexpensively with the use of Structure-from-Motion (SfM) photogrammetry. Traditional methods of measuring surface slip (e.g. manual measurement with tape measures) have proven inconsistent and irreproducible, and sophisticated methods such as laser scanning require specialized equipment and longer field time. Here we present a simple, cost-effective workflow for rapid, three-dimensional imaging and measurement of features affected by earthquake rupture. As part of a response drill performed by the USGS and collaborators on May 11, 2016, geologists documented offset cultural features along the creeping Hayward Fault in northern California, in simulation of a surface-rupturing earthquake. We present several photo collections from smart phones, tablets, and DSLR cameras from a number of locations along the fault collected by users with a range of experience. Using professionally calibrated photogrammetric scale bars we automatically and accurately scale our 3D models to 1 mm accuracy for precise measurement in three dimensions. We then generate scaled 3D point clouds and extract offsets from manual measurement and multiple linear regression for comparison with collected terrestrial scanner data. These results further establish dense photo collection and SfM processing as an important, low-cost, rapid means of quantifying surface deformation in the critical hours after a surface-rupturing earthquake and emphasize that researchers with minimal training can rapidly collect three-dimensional data that can be used to analyze and archive the surface effects of damaging earthquakes.

What can friction tell us about shallow megathrust slip behavior?

NASA Astrophysics Data System (ADS)

Ikari, M.; Kopf, A.; Hirose, T.

2012-12-01

In subduction zones, the updip propagation of great earthquake ruptures on plate boundary megathrusts is currently one of the most important questions in earth science, primarily because rupture that approaches the surface causes seafloor displacement, resulting in enormous tsunamis. Moreover, the extent of updip rupture propagation is a key factor in defining the magnitude of the earthquake itself. Within the depth limits of the seismogenic zone, velocity-weakening frictional behavior is essential for the nucleation of large-magnitude earthquake rupture. Results of friction experiments at low slip velocities (~10-6-10-4 m/s) have suggested that velocity-weakening tends to occur in frictionally strong materials (typically non-clay), which may act as asperities on fault surfaces. However, the role of frictional strength and velocity dependence in controlling the extent of rupture propagation beyond the updip limit of the seismogenic zone is still unclear. Low to high-velocity friction experiments have provided insights into fault strength evolution over slip velocities spanning ~10 orders of magnitude, from plate convergence rates to coseismic slip rates. Results using primarily non-clay materials typically exhibit high friction at low velocities that progressively weakens at higher velocities (velocity-weakening), becoming nearly frictionless at coseismic slip rates [Di Toro et al., 2011]. However, the shallow near-trench regions of subduction zones are typically rich in clay minerals which are weak (friction coefficient ≤ ~0.4) and velocity-strengthening at slip rates < 10-3 m/s. A compilation of friction experiments using samples from the Nankai Trough region offshore Japan obtained by scientific ocean drilling shows that this material exhibits such behavior at low to intermediate slip velocities. However, after reaching peak values at ~10-2 m/s, these materials also exhibit a precipitous drop in friction toward near-zero values at coseismic slip rates. This suggests that all geologic materials, regardless of composition, are extremely weak when coseismic slip rates are enforced. Therefore, the likelihood of near-trench rupture propagation in subduction zones depends critically on whether slip can reach velocities ≥ ~10-2 m/s, where dynamic weakening becomes dominant. This depends on whether the propagating earthquake rupture can overcome the overall strength of the fault gouge and/or velocity-strengthening behavior at low to intermediate slip rates. We discuss here the possibility of near-trench earthquake rupture at Nankai and other subduction zones on the basis of laboratory friction measurements.

Radiated energy and the rupture process of the Denali fault earthquake sequence of 2002 from broadband teleseismic body waves

USGS Publications Warehouse

Choy, G.L.; Boatwright, J.

2004-01-01

Displacement, velocity, and velocity-squared records of P and SH body waves recorded at teleseismic distances are analyzed to determine the rupture characteristics of the Denali fault, Alaska, earthquake of 3 November 2002 (MW 7.9, Me 8.1). Three episodes of rupture can be identified from broadband (???0.1-5.0 Hz) waveforms. The Denali fault earthquake started as a MW 7.3 thrust event. Subsequent right-lateral strike-slip rupture events with centroid depths of 9 km occurred about 22 and 49 sec later. The teleseismic P waves are dominated by energy at intermediate frequencies (0.1-1 Hz) radiated by the thrust event, while the SH waves are dominated by energy at lower frequencies (0.05-0.2 Hz) radiated by the strike-slip events. The strike-slip events exhibit strong directivity in the teleseismic SH waves. Correcting the recorded P-wave acceleration spectra for the effect of the free surface yields an estimate of 2.8 ?? 1015 N m for the energy radiated by the thrust event. Correcting the recorded SH-wave acceleration spectra similarly yields an estimate of 3.3 ?? 10 16 N m for the energy radiated by the two strike-slip events. The average rupture velocity for the strike-slip rupture process is 1.1??-1.2??. The strike-slip events were located 90 and 188 km east of the epicenter. The rupture length over which significant or resolvable energy is radiated is, thus, far shorter than the 340-km fault length over which surface displacements were observed. However, the seismic moment released by these three events, 4 ?? 1020 N m, was approximately half the seismic moment determined from very low-frequency analyses of the earthquake. The difference in seismic moment can be reasonably attributed to slip on fault segments that did not radiate significant or coherent seismic energy. These results suggest that very large and great strike-slip earthquakes can generate stress pulses that rapidly produce substantial slip with negligible stress drop and little discernible radiated energy on fault segments distant from the initial point of nucleation. The existence of this energy-deficient rupture mode has important implications for the evaluation of the seismic hazard of very large strike-slip earthquakes.

Structural Geology of the Northwestern Portion of Los Alamos National Laboratory, Rio Grande Rift, New Mexico: Implications for Seismic Surface Rupture Potential from TA-3 to TA-55

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jamie N. Gardner: Alexis Lavine; Giday WoldeGabriel; Donathon Krier

1999-03-01

Los Alamos National Laboratory lies at the western boundary of the Rio Grande rift, a major tectonic feature of the North American Continent. Three major faults locally constitute the modem rift boundary, and each of these is potentially seismogenic. In this study we have gathered structural geologic data for the northwestern portion of Los Alamos National Laboratory through high-precision geologic mapping, conventional geologic mapping, stratigraphic studies, drilling, petrologic studies, and stereographic aerial photograph analyses. Our study area encompasses TA-55 and TA-3, where potential for seismic surface rupture is of interest, and is bounded on the north and south by themore » townsite of Los Alamos and Twomile Canyon, respectively. The study area includes parts of two of the potentially active rift boundary faults--the Pajarito and Rendija Canyon faults-that form a large graben that we name the Diamond Drive graben. The graben embraces the western part of the townsite of Los Alamos, and its southern end is in the TA-3 area where it is defined by east-southeast-trending cross faults. The cross faults are small, but they accommodate interactions between the two major fault zones and gentle tilting of structural blocks to the north into the graben. North of Los Alamos townsite, the Rendija Canyon fault is a large normal fault with about 120 feet of down-to-the-west displacement over the last 1.22 million years. South from Los Alamos townsite, the Rendija Canyon fault splays to the southwest into a broad zone of deformation. The zone of deformation is about 2,000 feet wide where it crosses Los Alamos Canyon and cuts through the Los Alamos County Landfill. Farther southwest, the fault zone is about 3,000 feet wide at the southeastern corner of TA-3 in upper Mortandad Canyon and about 5,000 feet wide in Twomile Canyon. Net down-to-the-west displacement across the entire fault zone over the last 1.22 million years decreases to the south as the fault zone broadens as follows: about 100 feet at Los Alamos Canyon, about 50 feet at upper Mortandad Canyon, and less than 30 feet at Twomile Canyon. These relations lead us to infer that the Rendija Canyon fault probably dies out just south of Twomile Canyon. In detail, the surface deformation expressed within the fault zones can be large, fairly simple normal faults, broad zones of smaller faults, largely unfaulted monocline, and faulted monocline. Our study indicates that the seismic surface rupture hazard, associated with the faults in the study area, is localized. South of the county landfill and Los Alamos Canyon, displacements on individual faults become very small, less than about 10 feet in the last 1.22 million years. Such small displacements imply that these little faults do not have much continuity along strike and in a worst-case scenario present a mean probabilistic fault displacement hazard of less than 0.67 inches in 10,000 years (Olig et al., 1998). We encourage, however, site-specific fault investigations for new construction in certain zones of our study area and that facility siting on potentially active faults be avoided.« less

Modelling and Experimental Verification of Pressure Wave Following Gaseous Helium Storage Tank Rupture

NASA Astrophysics Data System (ADS)

Chorowski, M.; Grabowski, M.; Jędrusyna, A.; Wach, J.

Helium inventory in high energy accelerators, tokamaks and free electron lasers may exceed tens of tons. The gaseous helium is stored in steel tanks under a pressure of about 20 bar and at environment temperature. Accidental rupture of any of the tanks filled with the gaseous helium will create a rapid energy release in form of physical blast. An estimation of pressure wave distribution following the tank rupture and potential consequences to the adjacent research infrastructure and buildings is a very important task, critical in the safety aspect of the whole cryogenic system. According to the present regulations the TNT equivalent approach is to be applied to evaluate the pressure wave following a potential gas storage tank rupture. A special test stand was designed and built in order to verify experimentally the blast effects in controlled conditions. In order to obtain such a shock wave a pressurized plastic tank was used. The tank was ruptured and the resulting pressure wave was recorded using a spatially-distributed array of pressure sensors connected to a high-speed data acquisition device. The results of the experiments and the comparison with theoretical values obtained from thermodynamic model of the blast are presented. A good agreement between the simulated and measured data was obtained. Recommendations regarding the applicability of thermodynamic model of physical blast versus TNT approach, to estimate consequences of gas storage tank rupture are formulated. The laboratory scale experimental results have been scaled to ITER pressurized helium storage tanks.

Dynamic rupture modeling of the M7.2 2010 El Mayor-Cucapah earthquake: Comparison with a geodetic model

USGS Publications Warehouse

Kyriakopoulos, Christos; Oglesby, David D.; Funning, Gareth J.; Ryan, Kenneth

2017-01-01

The 2010 Mw 7.2 El Mayor-Cucapah earthquake is the largest event recorded in the broader Southern California-Baja California region in the last 18 years. Here we try to analyze primary features of this type of event by using dynamic rupture simulations based on a multifault interface and later compare our results with space geodetic models. Our results show that starting from homogeneous prestress conditions, slip heterogeneity can be achieved as a result of variable dip angle along strike and the modulation imposed by step over segments. We also considered effects from a topographic free surface and find that although this does not produce significant first-order effects for this earthquake, even a low topographic dome such as the Cucapah range can affect the rupture front pattern and fault slip rate. Finally, we inverted available interferometric synthetic aperture radar data, using the same geometry as the dynamic rupture model, and retrieved the space geodetic slip distribution that serves to constrain the dynamic rupture models. The one to one comparison of the final fault slip pattern generated with dynamic rupture models and the space geodetic inversion show good agreement. Our results lead us to the following conclusion: in a possible multifault rupture scenario, and if we have first-order geometry constraints, dynamic rupture models can be very efficient in predicting large-scale slip heterogeneities that are important for the correct assessment of seismic hazard and the magnitude of future events. Our work contributes to understanding the complex nature of multifault systems.

Finite-fault inversion of the Mw 5.9 2012 Emilia-Romagna earthquake (Northern Italy) using aftershocks as near-field Green's function approximations

NASA Astrophysics Data System (ADS)

Causse, Mathieu; Cultrera, Giovanna; Herrero, André; Courboulex, Françoise; Schiappapietra, Erika; Moreau, Ludovic

2017-04-01

On May 29, 2012 occurred a Mw 5.9 earthquake in the Emilia-Romagna region (Po Plain) on a thrust fault system. This shock, as well as hundreds of aftershocks, were recorded by 10 strong motion stations located less than 10 km away from the rupture plane, with 4 stations located within the surface rupture projection. The Po Plain is a very large EW trending syntectonic alluvial basin, delimited by the Alps and Apennines chains to the North and South. The Plio-Quaternary sedimentary sequence filling the Po Plain is characterized by an uneven thickness, ranging from several thousands of meters to a few tens of meters. This particular context results especially in a resonance basin below 1 Hz and strong surface waves, which makes it particularly difficult to model wave propagation and hence to obtain robust images of the rupture propagation. This study proposes to take advantage of the large set of recorded aftershocks, considered as point sources, to model wave propagation. Due to the heterogeneous distribution of the aftershocks on the fault plane, an interpolation technique is proposed to compute an approximation of the Green's function between each fault point and each strong motion station in the frequency range [0.2-1Hz]. We then use a Bayesian inversion technique (Monte Carlo Markov Chain algorithm) to obtain images of the rupture propagation from the strong motion data. We propose to retrieve the slip distribution by inverting the final slip value at some control points, which are allowed to move on the fault plane, and by interpolating the slip value between these points. We show that the use of 5 control points to describe the slip, coupled with the hypothesis of spatially constant rupture velocity and rise-time (that is 18 free source parameters), results in a good level of fit with the data. This indicates that despite their complexity, the strong motion data can be properly modeled up to 1 Hz using a relatively simple rupture. The inversion results also reveal that the rupture propagated slowly, at a speed of about 45% of the shear wave velocity.

Dynamic rupture simulations on complex fault zone structures with off-fault plasticity using the ADER-DG method

NASA Astrophysics Data System (ADS)

Wollherr, Stephanie; Gabriel, Alice-Agnes; Igel, Heiner

2015-04-01

In dynamic rupture models, high stress concentrations at rupture fronts have to to be accommodated by off-fault inelastic processes such as plastic deformation. As presented in (Roten et al., 2014), incorporating plastic yielding can significantly reduce earlier predictions of ground motions in the Los Angeles Basin. Further, an inelastic response of materials surrounding a fault potentially has a strong impact on surface displacement and is therefore a key aspect in understanding the triggering of tsunamis through floor uplifting. We present an implementation of off-fault-plasticity and its verification for the software package SeisSol, an arbitrary high-order derivative discontinuous Galerkin (ADER-DG) method. The software recently reached multi-petaflop/s performance on some of the largest supercomputers worldwide and was a Gordon Bell prize finalist application in 2014 (Heinecke et al., 2014). For the nonelastic calculations we impose a Drucker-Prager yield criterion in shear stress with a viscous regularization following (Andrews, 2005). It permits the smooth relaxation of high stress concentrations induced in the dynamic rupture process. We verify the implementation by comparison to the SCEC/USGS Spontaneous Rupture Code Verification Benchmarks. The results of test problem TPV13 with a 60-degree dipping normal fault show that SeisSol is in good accordance with other codes. Additionally we aim to explore the numerical characteristics of the off-fault plasticity implementation by performing convergence tests for the 2D code. The ADER-DG method is especially suited for complex geometries by using unstructured tetrahedral meshes. Local adaptation of the mesh resolution enables a fine sampling of the cohesive zone on the fault while simultaneously satisfying the dispersion requirements of wave propagation away from the fault. In this context we will investigate the influence of off-fault-plasticity on geometrically complex fault zone structures like subduction zones or branched faults. Studying the interplay of stress conditions and angle dependence of neighbouring branches including inelastic material behaviour and its effects on rupture jumps and seismic activation helps to advance our understanding of earthquake source processes. An application is the simulation of a real large-scale subduction zone scenario including plasticity to validate the coupling of our dynamic rupture calculations to a tsunami model in the framework of the ASCETE project (http://www.ascete.de/). Andrews, D. J. (2005): Rupture dynamics with energy loss outside the slip zone, J. Geophys. Res., 110, B01307. Heinecke, A. (2014), A. Breuer, S. Rettenberger, M. Bader, A.-A. Gabriel, C. Pelties, A. Bode, W. Barth, K. Vaidyanathan, M. Smelyanskiy and P. Dubey: Petascale High Order Dynamic Rupture Earthquake Simulations on Heterogeneous Supercomputers. In Supercomputing 2014, The International Conference for High Performance Computing, Networking, Storage and Analysis. IEEE, New Orleans, LA, USA, November 2014. Roten, D. (2014), K. B. Olsen, S.M. Day, Y. Cui, and D. Fäh: Expected seismic shaking in Los Angeles reduced by San Andreas fault zone plasticity, Geophys. Res. Lett., 41, 2769-2777.

[Secondary Splenic Rupture after Initially Inconspicuous CAT Scan].

PubMed

Prokop, A; Koll, S; Chmielnicki, M

2016-04-01

Splenic injuries occur in 1-5 % of blunt abdominal trauma cases. After initial haemorrhagic compression, secondary delayed spleen rupture can occur with a latency of one day to a month or longer. Mortality is then up to 15 %. The spleen injury is almost always recognisable on CT or ultrasound. In one case from our clinic, secondary splenic rupture occurred in a patient after discharge from hospitalisation, even though the initial CT and ultrasound were unremarkable. The patient survived, and underwent emergent splenectomy 8 days after the trauma. An expert review of the case identified no errors in treatment. No case of secondary splenic rupture after initially unremarkable diagnostic studies and clinical course has previously been published. Secondary splenic rupture has a high mortality rate. Patients should be advised of potential complications after hospital discharge, and should return to the hospital immediately in case of symptoms. Georg Thieme Verlag KG Stuttgart · New York.

SURFACE RUPTURE OF THE NORMAL SEISMIC FAULTS AND SLOPE FAILURES APPEARED IN APRIL 11th, 2011 FUKUSHIMA-PREFECTURE HAMADOORI EARTHQUAKE

NASA Astrophysics Data System (ADS)

Kazmi, Zaheer Abbas; Konagai, Kazuo; Kyokawa, Hiroyuki; Tetik, Cigdem

On April 11th, 2011, Iwaki region of Fukushima prefecture was jolted by Fukushima-Prefecture Hamadoori Earthquake. Surface ruptures were observed along causative Idosawa and Yunotake normal faults. In addition to numerous small slope failures, a coherent landslide and building structures of Tabito Junior High School, bisected by Idosawa Fault, were found along the causative faults. A precise digital elevation model of the coherent landslide was obtained through the ground and air-born LiDAR surveys. The measurements of perimeters of the gymnasium building and the swimming pool of Tabito Junior High School have shown that ground undergoes a slow and steady/continual deformation.

Kinetics of the Multistep Rupture of Fibrin ‘A-a’ Polymerization Interactions Measured Using Atomic Force Microscopy

PubMed Central

Averett, Laurel E.; Schoenfisch, Mark H.; Akhremitchev, Boris B.; Gorkun, Oleg V.

2009-01-01

Abstract Fibrin, the structural scaffold of blood clots, spontaneously polymerizes through the formation of ‘A-a’ knob-hole bonds. When subjected to external force, the dissociation of this bond is accompanied by two to four abrupt changes in molecular dimension observable as rupture events in a force curve. Herein, the configuration, molecular extension, and kinetic parameters of each rupture event are examined. The increases in contour length indicate that the D region of fibrinogen can lengthen by ∼50% of the length of a fibrin monomer before rupture of the ‘A-a’ interaction. The dependence of the dissociation rate on applied force was obtained using probability distributions of rupture forces collected at different pull-off velocities. These distributions were fit using a model in which the effects of the shape of the binding potential are used to quantify the kinetic parameters of forced dissociation. We found that the weak initial rupture (i.e., event 1) was not well approximated by these models. The ruptured bonds comprising the strongest ruptures, events 2 and 3, had kinetic parameters similar to those commonly found for the mechanical unfolding of globular proteins. The bonds ruptured in event 4 were well described by these analyses, but were more loosely bound than the bonds in events 2 and 3. We propose that the first event represents the rupture of an unknown interaction parallel to the ‘A-a’ bond, events 2 and 3 represent unfolding of structures in the D region of fibrinogen, and event 4 is the rupture of the ‘A-a’ knob-hole bond weakened by prior structural unfolding. Comparison of the activation energy obtained via force spectroscopy measurements with the thermodynamic free energy of ‘A-a’ bond dissociation indicates that the ‘A-a’ bond may be more resistant to rupture by applied force than to rupture by thermal dissociation. PMID:19917237

Co-seismic and cumulative slip along the Kokoxili Mw 7.9 earthquake rupture (Kunlun Fault, northeastern Tibet)

NASA Astrophysics Data System (ADS)

van der Woerd, J.; Klinger, Y.; Xu, X.; Ledortz, K.; Tapponnier, P.; Li, H.; King, G.; Ma, W.; Chen, W.

2009-04-01

Co-seismic slip values along a strike-slip rupture are found to be very irregular with variations up to one order of magnitude. Data usually scattered and sparse, are more dense and continuous with slip functions derived from InSAR or image correlations. Whether the fast variations in slip along strike reveals long-lived structures of the fault plane at depth, only incomplete slip at the surface or inelastic accommodation of slip remains debated. In addition, how these slip disparities are accommodated with time is unclear. The surface breaks of the Kokoxili Mw 7.9 event sytematically follow the geomorphic trace of the fault, which bears evidence for cumulative displacements. In the epicentral area, the rupture steps along the highest ice-capped summit of the region, the Buka Daban Feng. Evidence for normal fault breaks, left-lateral ruptures and steep triangular facets indicate that the Buka Daban Feng, a 40 km-long range reaching about 6800 m a.s.l. formed as a result of continuous oblique left-normal faulting. Normal faulting is attested by hanging glaciers, a steep southeastern flank and hot springs along coseismic and cumulative surface ruptures. Left-lateral movement along the main oblique normal fault has displaced the distal frontal moraines of almost all glacial valleys. West of the Buka Daban Feng, the western most ruptured strand is continuous between Kushiwan and Tayang lakes (about 60 km long) with coseismic left-lateral offsets reaching 4-5 m. To the east, at one site, the rupture splays into 4 main, N90°E-striking strands across a 1200x300m pull-apart. Three strands show right-stepping scarps with maximum throws of 1 m. The northern strand shows 3 m of purely normal throw. On NS profiles, the coseismic subsidence of the pull-apart floor was about 2 m, 1/10th of its 20 m depth, consistent with the repetition of 10 comparable earthquakes. East of the pull-apart 5 +/- 0.2 m sinistral slip are measured on the single stranded rupture. A similar coseismic sinistral slip value (4.8 +/- 0.4 m), with a thrust throw of 0.75 m, is found across two lake shorelines (1 and 2.3 meters above lake level), about 1.5 km farther east. At one river channel site, 15 km farther east, we measured a larger coseismic sinistral offset. The lowest terrace riser, between the active river bed and the lowest terrace is offset by about 10 m. Two older terrace risers show cumulative offsets twice as large (about 20 m). The largest cumulative offset measured reaches 50 m. Thirty kilometers yet farther east, near a glacial outlet at the foot of the Yuxi Shan, 4 distinct rills are offset by 3.5 m along the main surface break while smaller offsets (1-1.5 m) characterize a secondary break 250 m southwards. We have investigated in more detail the co-seismic and paleo-seismic slip near the central part of the rupture, where a set of about 10 inset terraces is used to infer the slip history of the fault. The particularly low co-seismic slip value at the site, about 2.4 +/- 0.6 m, lower than the value derived from Spot image correlation or from Insar, follows a maximum slip value of about 8 m only a few kilometres to the west. Site interpretation from field data, total station measurements and high resolution Ikonos images allow to reconstruct the different riser offsets across the damaged rupture zone. 10Be cosmogenic nuclide exposure ages of cobbles from the surface of the terraces allow to constrain the age the terraces and to infer an average slip-rate of 10-15 mm/yr in good agreement with previous results along the fault. When a characteristic slip model is considered, and depending of the measurement method or location of coseismic slip, the recurrence time for events comparable to the Mw 7.9 Kokoxili event may vary from 200 to 800 years.

Evaluation of potential surface rupture and review of current seismic hazards program at the Los Alamos National Laboratory. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-12-09

This report summarizes the authors review and evaluation of the existing seismic hazards program at Los Alamos National Laboratory (LANL). The report recommends that the original program be augmented with a probabilistic analysis of seismic hazards involving assignment of weighted probabilities of occurrence to all potential sources. This approach yields a more realistic evaluation of the likelihood of large earthquake occurrence particularly in regions where seismic sources may have recurrent intervals of several thousand years or more. The report reviews the locations and geomorphic expressions of identified fault lines along with the known displacements of these faults and last knowmore » occurrence of seismic activity. Faults are mapped and categorized into by their potential for actual movement. Based on geologic site characterization, recommendations are made for increased seismic monitoring; age-dating studies of faults and geomorphic features; increased use of remote sensing and aerial photography for surface mapping of faults; the development of a landslide susceptibility map; and to develop seismic design standards for all existing and proposed facilities at LANL.« less

Asymptotic decay and non-rupture of viscous sheets

NASA Astrophysics Data System (ADS)

Fontelos, Marco A.; Kitavtsev, Georgy; Taranets, Roman M.

2018-06-01

For a nonlinear system of coupled PDEs, that describes evolution of a viscous thin liquid sheet and takes account of surface tension at the free surface, we show exponential (H^1, L^2) asymptotic decay to the flat profile of its solutions considered with general initial data. Additionally, by transforming the system to Lagrangian coordinates we show that the minimal thickness of the sheet stays positive for all times. This result proves the conjecture formally accepted in the physical literature (cf. Eggers and Fontelos in Singularities: formation, structure, and propagation. Cambridge Texts in Applied Mathematics, Cambridge, 2015), that a viscous sheet cannot rupture in finite time in the absence of external forcing. Moreover, in the absence of surface tension we find a special class of initial data for which the Lagrangian solution exhibits L^2-exponential decay to the flat profile.

Interactions between strike-slip earthquakes and the subduction interface near the Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Gong, Jianhua; McGuire, Jeffrey J.

2018-01-01

The interactions between the North American, Pacific, and Gorda plates at the Mendocino Triple Junction (MTJ) create one of the most seismically active regions in North America. The earthquakes rupture all three plate boundaries but also include considerable intraplate seismicity reflecting the strong internal deformation of the Gorda plate. Understanding the stress levels that drive these ruptures and estimating the locking state of the subduction interface are especially important topics for regional earthquake hazard assessment. However owing to the lack of offshore seismic and geodetic instruments, the rupture process of only a few large earthquakes near the MTJ have been studied in detail and the locking state of the subduction interface is not well constrained. In this paper, first, we use the second moments inversion method to study the rupture process of the January 28, 2015 Mw 5.7 earthquake on the Mendocino transform fault that was unusually well recorded by both onshore and offshore strong motion instruments. We estimate the rupture dimension to be approximately 6 km by 3 km corresponding to a stress drop of ∼4 MPa for a crack model. Next we investigate the frictional state of the subduction interface by simulating the afterslip that would be expected there as a result of the stress changes from the 2015 earthquake and a 2010 Mw 6.5 intraplate earthquake within the subducted Gorda plate. We simulate afterslip scenarios for a range of depths of the downdip end of the locked zone defined as the transition to velocity strengthening friction and calculate the corresponding surface deformation expected at onshore GPS monuments. We can rule out a very shallow downdip limit owing to the lack of a detectable signal at onshore GPS stations following the 2010 earthquake. Our simulations indicate that the locking depth on the slab surface is at least 14 km, which suggests that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected there.

Full Aftershock Sequence of the M w 6.9 2003 Boumerdes Earthquake, Algeria: Space-Time Distribution, Local Tomography and Seismotectonic Implications

NASA Astrophysics Data System (ADS)

Kherroubi, Abdelaziz; Yelles-Chaouche, Abdelkrim; Koulakov, Ivan; Déverchère, Jacques; Beldjoudi, Hamoud; Haned, Abderrahmane; Semmane, Fethi; Aidi, Chafik

2017-07-01

We present a detailed analysis of the aftershocks of the May 21, 2003 Boumerdes earthquake ( M w = 6.9) recorded by 35 seismological stations and 2 OBS deployed in the epicentral area. This network recorded the aftershock activity for about 1 year and resulted in locating about 2500 events. The five main aftershocks (4.7 < M <5.8) display thrust faulting consistent with the main shock, except for the second event (M5.8, 29/05/2003) which depicts a strike-slip focal solution at the western tip of the rupture zone. Most aftershocks are clustered near the main rupture plane, in the footwall or at the westernmost tip of the 2003 Boumerdes rupture area. Many aftershocks last over the whole seismic crisis ahead (north) of the main rupture zone, forming a diffuse, low-angle surface within the footwall where the coseismic static stress change is predicted to increase. At the SW tip of the rupture, short-lived clusters locate at intersections of faults near the contact between the inner (Kabylia) and outer (Tell) zones. The tomographic inversion depicts high-velocity P- and S-wave anomalies coinciding with Miocene magmatic intrusive bodies in the upper crust, partially hidden by surrounding basins. The area of the main shock is associated with a large low-velocity body subdivided into sub-domains, including Neogene basins on land and offshore. Our results support a rupture model strongly controlled by geological inhomogeneities and extending as ramp-flat-ramp systems upward, favoring heterogeneous slip and segmentation in the fault plane with strong afterslip toward the surface. The diffuse aftershock activity in the footwall evidences an inherited discontinuity at mid-crustal depth that we interpret as the contact of Kabylian and African (Tethyan) continental crusts that were stacked during the Upper Miocene collision.

Tear-Film Evaporation Rate from Simultaneous Ocular-Surface Temperature and Tear-Breakup Area.

PubMed

Dursch, Thomas J; Li, Wing; Taraz, Baseem; Lin, Meng C; Radke, Clayton J

2018-01-01

A corneal heat-transfer model is presented to quantify simultaneous measurements of fluorescein tear-breakup area (TBA) and ocular-surface temperature (OST). By accounting for disruption of the tear-film lipid layer (TFLL), we report evaporation rates through lipid-covered tear. The modified heat-transfer model provides new insights into evaporative dry eye. A quantitative analysis is presented to assess human aqueous tear evaporation rate (TER) through intact TFLLs from simultaneous in vivo measurement of time-dependent infrared OST and fluorescein TBA. We interpret simultaneous OST and TBA measurements using an extended heat-transfer model. We hypothesize that TBAs are ineffectively insulated by the TFLL and therefore exhibit higher TER than does that for a well-insulting TFLL-covered tear. As time proceeds, TBAs increase in number and size, thereby increasing the cornea area-averaged TER and decreasing OST. Tear-breakup areas were assessed from image analysis of fluorescein tear-film-breakup video recordings and are included in the heat-transfer description of OST. Model-predicted OSTs agree well with clinical experiments. Percent reductions in TER of lipid-covered tear range from 50 to 95% of that for pure water, in good agreement with literature. The physical picture of noninsulating or ruptured TFLL spots followed by enhanced evaporation from underlying cooler tear-film ruptures is consistent with the evaporative-driven mechanism for local tear rupture. A quantitative analysis is presented of in vivo TER from simultaneous clinical measurement of transient OST and TBA. The new heat-transfer model accounts for increased TER through expanding TBAs. Tear evaporation rate varies strongly across the cornea because lipid is effectively missing over tear-rupture troughs. The result is local faster evaporation compared with nonruptured, thick lipid-covered tear. Evaporative-driven tear-film ruptures deepen to a thickness where fluorescein quenching commences and local salinity rises to uncomfortable levels. Mitigation of tear-film rupture may therefore reduce dry eye-related symptoms.

The 1999 Hector Mine Earthquake, Southern California: Vector Near-Field Displacements from ERS InSAR

NASA Technical Reports Server (NTRS)

Sandwell, David T.; Sichoix, Lydie; Smith, Bridget

2002-01-01

Two components of fault slip are uniquely determined from two line-of-sight (LOS) radar interferograms by assuming that the fault-normal component of displacement is zero. We use this approach with ascending and descending interferograms from the ERS satellites to estimate surface slip along the Hector Mine earthquake rupture. The LOS displacement is determined by visually counting fringes to within 1 km of the outboard ruptures. These LOS estimates and uncertainties are then transformed into strike- and dip-slip estimates and uncertainties; the transformation is singular for a N-S oriented fault and optimal for an E-W oriented fault. In contrast to our previous strike-slip estimates, which were based only on a descending interferogram, we now find good agreement with the geological measurements, except at the ends of the rupture. The ascending interferogram reveals significant west-sidedown dip-slip (approximately 1.0 m) which reduces the strike-slip estimates by 1 to 2 m, especially along the northern half of the rupture. A spike in the strike-slip displacement of 6 m is observed in central part of the rupture. This large offset is confirmed by subpixel cross correlation of features in the before and after amplitude images. In addition to strike slip and dip slip, we identify uplift and subsidence along the fault, related to the restraining and releasing bends in the fault trace, respectively. Our main conclusion is that at least two look directions are required for accurate estimates of surface slip even along a pure strike-slip fault. Models and results based only on a single look direction could have major errors. Our new estimates of strike slip and dip slip along the rupture provide a boundary condition for dislocation modeling. A simple model, which has uniform slip to a depth of 12 km, shows good agreement with the observed ascending and descending interferograms.

Late Holocene paleoseismology of Shuyak Island, Kodiak Archipelago, Alaska - surface deformation and plate segmentation within the 1964 Alaska M 9.2 earthquake rupture zone

NASA Astrophysics Data System (ADS)

Brader, Martin; Shennan, Ian; Barlow, Natasha; Davies, Frank; Longley, Chris; Tunstall, Neil

2017-04-01

Recent paleoseismological studies question whether segment boundaries identified for 20th and 21st century great, >M 8, earthquakes persist through multiple earthquake cycles, or whether smaller segments with different boundaries rupture and cause significant hazards. The smaller segments may include some that are currently slipping rather than locked. The 1964 Alaska M 9.2 earthquake was the largest of five earthquakes of >M 7.9 between 1938 and 1965 along the Aleutian chain and coast of southcentral Alaska that helped define models of rupture segments along the Alaska-Aleutian megathrust. The 1964 M 9.2 earthquake ruptured ˜950 km of the megathrust, involving two main asperities focussed on Kodiak Island and Prince William Sound and crossed the Kenai segment, which is currently creeping. Paleoseismic studies of coastal sediments currently provide a long record of previous large earthquakes for the Prince William Sound segment, with widespread evidence of seven great earthquakes in the last 4000 years and more restricted evidence for three earlier ones. Shorter and more fragmentary records from the Kenai Peninsula, Yakataga and Kodiak Archipelago raise the hypothesis of different patterns of surface deformation during past great earthquakes. We present new evidence from coastal wetlands on Shuyak Island, towards the hypothesised north-eastern boundary of the Kodiak segment, to illustrate different detection limits of paleoseismic indicators and how these influence the identification of segment boundaries in late Holocene earthquakes. We compare predictions of co-seismic uplift and subsidence derived from geophysical models of earthquakes with different rupture modes. The spatial patterns of agreement and misfit between model predictions and quantitative reconstructions of co-seismic submergence and emergence suggest that no earthquake within the last 4000 years had the same rupture pattern as the 1964 M 9.2 earthquake.

Strong Ground Motion Analysis and Afterslip Modeling of Earthquakes near Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Gong, J.; McGuire, J. J.

2017-12-01

The Mendocino Triple Junction (MTJ) is one of the most seismically active regions in North America in response to the ongoing motions between North America, Pacific and Gorda plates. Earthquakes near the MTJ come from multiple types of faults due to the interaction boundaries between the three plates and the strong internal deformation within them. Understanding the stress levels that drive the earthquake rupture on the various types of faults and estimating the locking state of the subduction interface are especially important for earthquake hazard assessment. However due to lack of direct offshore seismic and geodetic records, only a few earthquakes' rupture processes have been well studied and the locking state of the subducted slab is not well constrained. In this study we first use the second moment inversion method to study the rupture process of the January 28, 2015 Mw 5.7 strike slip earthquake on Mendocino transform fault using strong ground motion records from Cascadia Initiative community experiment as well as onshore seismic networks. We estimate the rupture dimension to be of 6 km by 3 km and a stress drop of 7 MPa on the transform fault. Next we investigate the frictional locking state on the subduction interface through afterslip simulation based on coseismic rupture models of this 2015 earthquake and a Mw 6.5 intraplate eathquake inside Gorda plate whose slip distribution is inverted using onshore geodetic network in previous study. Different depths for velocity strengthening frictional properties to start at the downdip of the locked zone are used to simulate afterslip scenarios and predict the corresponding surface deformation (GPS) movements onshore. Our simulations indicate that locking depth on the slab surface is at least 14 km, which confirms that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected near the coast.

Coseismic fault slip associated with the 1992 M(sub w) 6.1 Joshua Tree, California, earthquake: Implications for the Joshua Tree-Landers earthquake sequence

NASA Technical Reports Server (NTRS)

Bennett, Richard A.; Reilinger, Robert E.; Rodi, William; Li, Yingping; Toksoz, M. Nafi; Hudnut, Ken

1995-01-01

Coseismic surface deformation associated with the M(sub w) 6.1, April 23, 1992, Joshua Tree earthquake is well represented by estimates of geodetic monument displacements at 20 locations independently derived from Global Positioning System and trilateration measurements. The rms signal to noise ratio for these inferred displacements is 1.8 with near-fault displacement estimates exceeding 40 mm. In order to determine the long-wavelength distribution of slip over the plane of rupture, a Tikhonov regularization operator is applied to these estimates which minimizes stress variability subject to purely right-lateral slip and zero surface slip constraints. The resulting slip distribution yields a geodetic moment estimate of 1.7 x 10(exp 18) N m with corresponding maximum slip around 0.8 m and compares well with independent and complementary information including seismic moment and source time function estimates and main shock and aftershock locations. From empirical Green's functions analyses, a rupture duration of 5 s is obtained which implies a rupture radius of 6-8 km. Most of the inferred slip lies to the north of the hypocenter, consistent with northward rupture propagation. Stress drop estimates are in the range of 2-4 MPa. In addition, predicted Coulomb stress increases correlate remarkably well with the distribution of aftershock hypocenters; most of the aftershocks occur in areas for which the mainshock rupture produced stress increases larger than about 0.1 MPa. In contrast, predicted stress changes are near zero at the hypocenter of the M(sub w) 7.3, June 28, 1992, Landers earthquake which nucleated about 20 km beyond the northernmost edge of the Joshua Tree rupture. Based on aftershock migrations and the predicted static stress field, we speculate that redistribution of Joshua Tree-induced stress perturbations played a role in the spatio-temporal development of the earth sequence culminating in the Landers event.

Laboratory studies of frictional sliding and the implications of precursory seismicity

NASA Astrophysics Data System (ADS)

Selvadurai, Paul A.

The dynamic transition from slow to rapid sliding along a frictional interface is of interest to geophysicists, engineers and scientists alike. In our direct shear experiment, we simulated a pre-existing frictional fault similar to those occurring naturally in the Earth. The laboratory study reported here has incorporated appropriate sensors that can detect foreshock events on the fringe of a nucleation zone prior to a gross fault rupture (main shock). During loading we observed foreshocks sequences as slip transitioned from slow to rapid sliding. These laboratory-induced foreshocks showed similar acoustic characteristics and spatio-temporal evolution as those detected in nature. Through direct observation (video camera), foreshocks were found to be the rapid, localized (millimeter length scale) failure of highly stresses asperities formed along the interface. The interface was created by the meshing of two rough polymethyl methacrylate (PMMA) bodies in a direct shear configuration. A carefully calibrated pressure sensitive film was used to map the contact junctions (asperities) throughout the interface at a range of applied normal loads Fn. Foreshocks were found to coalesce in a region of the fault that exhibited a more dense distribution of asperities (referred to as the seismogenic region). Microscopy of the interface in the seismogenic region displayed a variety of surface roughness at various length scales. This may have been introduced from the surface preparation techniques use to create a mature interface. The mature interface consisted of 'flat-topped' asperity regions with separating sharp valleys. The 'flat-topped' sections spanned millimetric length scales and were considerably flatter (nanometric roughness) that the roughness exhibited at longer length scales (tens of millimeters). We believe that the smoother, 'flat-topped' sections were responsible for the individual asperity formation (determining their size and strength), whereas the longer length scale roughness influenced the asperity-asperity interaction during the nucleation phase. Asperities in the seismogenic region where shown to exist close enough to each other so that elastic communication (through the off-fault material) could not be neglected. Prior to gross fault rupture (i.e. mainshock), we measured the propagation of a slow nucleating rupture into the relatively 'locked', seimsogenic region of the fault. Slow slip dynamics were captured using slip sensors placed along the fault that measured a non-uniform slip profile leading up to failure. We found that the propagation of the slow rupture into the locked region was dependent on the normal force Fn. Higher Fn was found to slow the propagation of shear rupture into the locked region. Within the relatively 'locked' region, a noticeable increase in size and a more compact spatial-temporal distribution of foreshocks were measured when Fn was increased. In order to develop an understanding of the relationship between Fn and the resistance of the fault to slow rupture, a quasi-static finite element (FE) model was developed. The model used distributions of asperities measured directly from the pressure sensitive film in a small section of the interface where foreshocks coalesced; specifically, the region where the slowly propagating slip front encountered the more dense distribution of asperities. A single asperity was modeled and followed the Cattaneo partial slip asperity solution. As the shear force increased along the fault, the asperities in this model were able to accommodate tangential slip by entering a partial sliding regime; the central contact of the asperities remained adhered while sliding accumulated along its periphery. Partial slip on the asperity propagated inwards as the shear force was incrementally increased. A further increase in the shear force caused the asperity to enter a full sliding condition. Increasing confining loads caused increased stiffness and increased capacity to store potential shear strain energy -- a possible measure of the 'degree of coupling' between the fault surfaces. Physics from the numerical model followed the qualitative observations made using photometry of asperities along the interface, which visualized asperities in the 'locked' region -- larger asperities remained stuck throughout the loading cycle and the light transmitted through individual asperities decreased from the periphery as shear loads increased. The numerical partial slip, quantified by the potential energy stored by the asperity, increased relative to the normal pressure p. Asperity-asperity interactions were modeled along the interface using a quasi-static analysis. Progression of slip into the asperity field was increasingly inhibited as the normal confining force Fn was increased. The computational model provided an explanation as to why an increased confining force Fn could result in an increased resistance to slow rupture as well as an increased potential for larger foreshocks within the resistive, relatively 'locked' section of a fault. This study lays the foundation for more innovative laboratory work that could potentially improve the phenomenological models currently used to estimate earthquake hazard. (Abstract shortened by UMI.).

Paleoseismic investigations in the Santa Cruz mountains, California: Implications for recurrence of large-magnitude earthquakes on the San Andreas fault

USGS Publications Warehouse

Schwartz, D.P.; Pantosti, D.; Okumura, K.; Powers, T.J.; Hamilton, J.C.

1998-01-01

Trenching, microgeomorphic mapping, and tree ring analysis provide information on timing of paleoearthquakes and behavior of the San Andreas fault in the Santa Cruz mountains. At the Grizzly Flat site alluvial units dated at 1640-1659 A.D., 1679-1894 A.D., 1668-1893 A.D., and the present ground surface are displaced by a single event. This was the 1906 surface rupture. Combined trench dates and tree ring analysis suggest that the penultimate event occurred in the mid-1600s, possibly in an interval as narrow as 1632-1659 A.D. There is no direct evidence in the trenches for the 1838 or 1865 earthquakes, which have been proposed as occurring on this part of the fault zone. In a minimum time of about 340 years only one large surface faulting event (1906) occurred at Grizzly Flat, in contrast to previous recurrence estimates of 95-110 years for the Santa Cruz mountains segment. Comparison with dates of the penultimate San Andreas earthquake at sites north of San Francisco suggests that the San Andreas fault between Point Arena and the Santa Cruz mountains may have failed either as a sequence of closely timed earthquakes on adjacent segments or as a single long rupture similar in length to the 1906 rupture around the mid-1600s. The 1906 coseismic geodetic slip and the late Holocene geologic slip rate on the San Francisco peninsula and southward are about 50-70% and 70% of their values north of San Francisco, respectively. The slip gradient along the 1906 rupture section of the San Andreas reflects partitioning of plate boundary slip onto the San Gregorio, Sargent, and other faults south of the Golden Gate. If a mid-1600s event ruptured the same section of the fault that failed in 1906, it supports the concept that long strike-slip faults can contain master rupture segments that repeat in both length and slip distribution. Recognition of a persistent slip rate gradient along the northern San Andreas fault and the concept of a master segment remove the requirement that lower slip sections of large events such as 1906 must fill in on a periodic basis with smaller and more frequent earthquakes.

Spontaneous rupture of the spleen detected on CT as the initial manifestation of infectious mononucleosis.

PubMed

Gayer, Gabriela; Zandman-Goddard, Gisele; Kosych, Elena; Apter, Sara

2003-04-01

Spontaneous splenic rupture after infectious mononucleosis (IM) is a rare, potentially fatal complication of IM, occurring in 0.1-0.5% of patients with proven IM. It usually occurs several weeks after the onset of symptoms, but may, rarely, be the initial manifestation of the disease. The patient is usually examined as an emergency due to severe abdominal pain and a falling hematocrit. The radiologist should be aware of the pathologic conditions involving the spleen which may lead to its spontaneous rupture.

Rupture Complexities of Fluid Induced Microseismic Events at the Basel EGS Project

NASA Astrophysics Data System (ADS)

Folesky, Jonas; Kummerow, Jörn; Shapiro, Serge A.; Häring, Markus; Asanuma, Hiroshi

2016-04-01

Microseismic data sets of excellent quality, such as the seismicity recorded in the Basel-1 enhanced geothermal system, Switzerland, in 2006-2007, provide the opportunity to analyse induced seismic events in great detail. It is important to understand in how far seismological insights on e.g. source and rupture processes are scale dependent and how they can be transferred to fluid induced micro-seismicity. We applied the empirical Green's function (EGF) method in order to reconstruct the relative source time functions of 195 suitable microseismic events from the Basel-1 reservoir. We found 93 solutions with a clear and consistent directivity pattern. The remaining events display either no measurable directivity, are unfavourably oriented or exhibit non consistent or complex relative source time functions. In this work we focus on selected events of M ˜ 1 which show possible rupture complexities. It is demonstrated that the EGF method allows to resolve complex rupture behaviour even if it is not directly identifiable in the seismograms. We find clear evidence of rupture directivity and multi-phase rupturing in the analysed relative source time functions. The time delays between consecutive subevents lies in the order of 10ms. Amplitudes of the relative source time functions of the subevents do not always show the same azimuthal dependence, indicating dissimilarity in the rupture directivity of the subevents. Our observations support the assumption that heterogeneity on fault surfaces persists down to small scale (few tens of meters).

[Conservative management of spontaneous splenic rupture as a complication of infectious mononucleosis: two case reports and literature review].

PubMed

Steiner-Linder, A; Ballmer, P E; Haller, A

2000-11-04

We report on conservative management of 2 patients with spontaneous splenic rupture associated with infectious mononucleosis. Both patients had an unremarkable hospital course and were discharged within 7 days of admission. Resolution of the haematoma was followed by ultrasound monitoring during the hospital stay. A literature review to 1999 shows that approximately 45 patients with serologically proven infectious mononucleosis have suffered spontaneous rupture of the spleen. Spontaneous splenic rupture is a rare but potentially fatal complication of infectious mononucleosis. Although splenectomy has been advocated in the past as the definitive therapy, we recommend that non-surgical management be considered in haemodynamically stable patients, to avoid the complications of splenectomy (e.g. post-splenectomy sepsis).

Tectonic interpretation of the 13 february 2001, mw 6.6, El Salvador Earthquake: New evidences of coseismic surface rupture and paleoseismic activity.

NASA Astrophysics Data System (ADS)

Martinez-Diaz, J. J.; Canora, C.; Villamor, P.; Capote, R.; Alvarez-Gomez, J. A.; Berryman, K.; Bejar, M.; Tsige, M.

2009-04-01

In February 2001 a major strike slip earthquake stroke the central part of El Salvador causing hundreds of people killed, thousands injured and extensive damage. After this event the scientific effort was mainly focused on the study of the enormous and catastrophic landslides triggered by this event and no evidences of surface faulting were detected. This earthquake was produced by the reactivation of the Ilopango-San Vicente segment of the El Salvador Fault Zone. Recently, a surface rupture displacement on the ground was identified. The analysis of aerial and field photographs taken few hours after the event and the mapping of the conserved ground structures shows a pure strike-slip displacement ranging from 20 to 50 cm, with secondary features indicating dextral shearing. The paleoseismic analysis made through the excavation of six trenches and Radiocarbon dating indicate a minimum slip rate of 2.0 mm/yr and a recurrence of major ruptures (Mw > 6.5) lower than 500 yr. These evidences give interesting local data to increase our understanding about the tectonic behavior and the way how active deformation develops along the northern limit of the forearc sliver related to the Centroamerican subduction area.

Dynamic fault rupture model of the 2008 Iwate-Miyagi Nairiku earthquake, Japan; Role of rupture velocity changes on extreme ground motions

NASA Astrophysics Data System (ADS)

Pulido Hernandez, N. E.; Dalguer Gudiel, L. A.; Aoi, S.

2009-12-01

The Iwate-Miyagi Nairiku earthquake, a reverse earthquake occurred in the southern Iwate prefecture Japan (2008/6/14), produced the largest peak ground acceleration recorded to date (4g) (Aoi et al. 2008), at the West Ichinoseki (IWTH25), KiK-net strong motion station of NIED. This station which is equipped with surface and borehole accelerometers (GL-260), also recorded very high peak accelerations up to 1g at the borehole level, despite being located in a rock site. From comparison of spectrograms of the observed surface and borehole records at IWTH25, Pulido et. al (2008) identified two high frequency (HF) ground motion events located at 4.5s and 6.3s originating at the source, which likely derived in the extreme observed accelerations of 3.9g and 3.5g at IWTH25. In order to understand the generation mechanism of these HF events we performed a dynamic fault rupture model of the Iwate-Miyagi Nairiku earthquake by using the Support Operator Rupture Dynamics (SORD) code, (Ely et al., 2009). SORD solves the elastodynamic equation using a generalized finite difference method that can utilize meshes of arbitrary structure and is capable of handling geometries appropriate to thrust earthquakes. Our spontaneous dynamic rupture model of the Iwate-Miyagi Nairiku earthquake is governed by the simple slip weakening friction law. The dynamic parameters, stress drop, strength excess and critical slip weakening distance are estimated following the procedure described in Pulido and Dalguer (2009) [PD09]. These parameters develop earthquake rupture consistent with the final slip obtained by kinematic source inversion of near source strong ground motion recordings. The dislocation model of this earthquake is characterized by a patch of large slip located ~7 km south of the hypocenter (Suzuki et al. 2009). Our results for the calculation of stress drop follow a similar pattern. Using the rupture times obtained from the dynamic model of the Iwate-Miyagi Nairiku earthquake we estimated the rupture velocity as well as rupture velocity changes distribution across the fault plane based on the procedure proposed by PD09. Our results show that rupture velocity has strong variations concentrated in small patches within large slip areas (asperities). Using this dynamic model we performed the strong motion simulation at the IWTH25 borehole. We obtained that this model is able to reproduce the two HF events observed in the strong motion data. Our preliminary results suggest that the extreme acceleration pulses were induced by two strong rupture velocity acceleration events at the rupture front. References Aoi, S., T. Kunugi, and H. Fujiwara, 2008, Science, 322, 727-730. Ely, G. P., S. M. Day, and J.-B. Minster (2009), Geophys. J. Int., 177(3), 1140-1150. Pulido, N., S. Aoi, and W. Suzuki (2008), AGU Fall meeting, S33C-02. Pulido, N., and L.A. Dalguer, (2009). Estimation of the high-frequency radiation of the 2000 Tottori (Japan) earthquake based on a dynamic model of fault rupture: Application to the strong ground motion simulation, Bull. Seism. Soc. Am. 99(4), 2305-2322. Suzuki, W., S. Aoi, and H. Sekiguchi, (2009), Bull. Seism. Soc. Am. (Accepted).

Electric field mediated breakdown of thin liquid films separating microscopic emulsion droplets

NASA Astrophysics Data System (ADS)

Mostowfi, Farshid; Khristov, Khristo; Czarnecki, Jan; Masliyah, Jacob; Bhattacharjee, Subir

2007-04-01

The authors present a microfluidic technique for electrically induced breakup of thin films formed between microscopic emulsion droplets. The method involves creating a stationary film at the intersection of two microchannels etched onto a glass substrate. After stabilizing the film, a ramped potential is applied across it. The electrical stresses developed at the film interfaces lead to its rupture above a threshold potential. The potential difference at which the film ruptures assesses the film stability. This approach is employed to demonstrate how surfactant (lecithin) adsorption imparts stability to an ultrathin oil film formed between two water droplets.

Molecular Imaging of Inflammation in Atherosclerosis

PubMed Central

Wildgruber, Moritz; Swirski, Filip K.; Zernecke, Alma

2013-01-01

Acute rupture of vulnerable plaques frequently leads to myocardial infarction and stroke. Within the last decades, several cellular and molecular players have been identified that promote atherosclerotic lesion formation, maturation and plaque rupture. It is now widely recognized that inflammation of the vessel wall and distinct leukocyte subsets are involved throughout all phases of atherosclerotic lesion development. The mechanisms that render a stable plaque unstable and prone to rupture, however, remain unknown and the identification of the vulnerable plaque remains a major challenge in cardiovascular medicine. Imaging technologies used in the clinic offer minimal information about the underlying biology and potential risk for rupture. New imaging technologies are therefore being developed, and in the preclinical setting have enabled new and dynamic insights into the vessel wall for a better understanding of this complex disease. Molecular imaging has the potential to track biological processes, such as the activity of cellular and molecular biomarkers in vivo and over time. Similarly, novel imaging technologies specifically detect effects of therapies that aim to stabilize vulnerable plaques and silence vascular inflammation. Here we will review the potential of established and new molecular imaging technologies in the setting of atherosclerosis, and discuss the cumbersome steps required for translating molecular imaging approaches into the clinic. PMID:24312156

Tsunamigenic earthquake simulations using experimentally derived friction laws

NASA Astrophysics Data System (ADS)

Murphy, S.; Di Toro, G.; Romano, F.; Scala, A.; Lorito, S.; Spagnuolo, E.; Aretusini, S.; Festa, G.; Piatanesi, A.; Nielsen, S.

2018-03-01

Seismological, tsunami and geodetic observations have shown that subduction zones are complex systems where the properties of earthquake rupture vary with depth as a result of different pre-stress and frictional conditions. A wealth of earthquakes of different sizes and different source features (e.g. rupture duration) can be generated in subduction zones, including tsunami earthquakes, some of which can produce extreme tsunamigenic events. Here, we offer a geological perspective principally accounting for depth-dependent frictional conditions, while adopting a simplified distribution of on-fault tectonic pre-stress. We combine a lithology-controlled, depth-dependent experimental friction law with 2D elastodynamic rupture simulations for a Tohoku-like subduction zone cross-section. Subduction zone fault rocks are dominantly incohesive and clay-rich near the surface, transitioning to cohesive and more crystalline at depth. By randomly shifting along fault dip the location of the high shear stress regions ("asperities"), moderate to great thrust earthquakes and tsunami earthquakes are produced that are quite consistent with seismological, geodetic, and tsunami observations. As an effect of depth-dependent friction in our model, slip is confined to the high stress asperity at depth; near the surface rupture is impeded by the rock-clay transition constraining slip to the clay-rich layer. However, when the high stress asperity is located in the clay-to-crystalline rock transition, great thrust earthquakes can be generated similar to the Mw 9 Tohoku (2011) earthquake.

Examination of the influence of coatings on thin superalloy sections. Volume 2: Detailed procedures and data. [corrosion resistance

NASA Technical Reports Server (NTRS)

Kaufman, M.

1974-01-01

The effects of an aluminide coating, Codep B-1, and of section thickness were investigated on two cast nickel base superalloys, Rene 80 and Rene 120. Cast section thicknesses ranged from 0.038 cm to 0.15 cm. Simulated engine exposures for 1000 hours at 899C or 982C in a jet fuel burner rig with cyclic air cooling were studied, as were the effects of surface machining before coating and re-machining and re-coating after exposures. The properties evaluated included tensile at room temperature., 871C and 982C, stress rupture at 760C, 871C, 982C and 1093C, high cycle mechanical fatigue at room temperature., and thermal fatigue with a 1093C peak temperature. Thin sections had tensile strengths similar to standard size bars up to 871C and lower strengths at 982C and above, with equivalent elongation, and stress rupture life was lower for thin sections at all test conditions. The aluminide coating lowered tensile and rupture strengths up to 871C, with greater effects on thinner specimens. Elevated temperature exposure lowered tensile and rupture strengths of thinner specimens at the lower test temperatures. Surface machining had little effect on properties, but re-machining after exposure reduced thickness and increased metallurgical changes enough to lower properties at most test conditions.

New Tsunami Forecast Tools for the French Polynesia Tsunami Warning System

NASA Astrophysics Data System (ADS)

Clément, Joël; Reymond, Dominique

2015-03-01

This paper presents the tsunami warning tools, which are used for the estimation of the seismic source parameters. These tools are grouped under a method called Preliminary Determination of Focal Mechanism_2 ( PDFM2), that has been developed at the French Polynesia Warning Center, in the framework of the system, as a plug-in concept. The first tool determines the seismic moment and the focal geometry (strike, dip, and slip), and the second tool identifies the "tsunami earthquakes" (earthquakes that cause much bigger tsunamis than their magnitude would imply). In a tsunami warning operation, initial assessment of the tsunami potential is based on location and magnitude. The usual quick magnitude methods which use waves, work fine for smaller earthquakes. For major earthquakes these methods drastically underestimate the magnitude and its tsunami potential because the radiated energy shifts to the longer period waves. Since French Polynesia is located far away from the subduction zones of the Pacific rim, the tsunami threat is not imminent, and this luxury of time allows to use the long period surface wave data to determine the true size of a major earthquake. The source inversion method presented in this paper uses a combination of surface waves amplitude spectra and P wave first motions. The advantage of using long period surface data is that there is a much more accurate determination of earthquake size, and the advantage of using P wave first motion is to have a better constrain of the focal geometry than using the surface waves alone. The method routinely gives stable results at minutes, with being the origin time of an earthquake. Our results are then compared to the Global Centroid Moment Tensor catalog for validating both the seismic moment and the source geometry. The second tool discussed in this paper is the slowness parameter and is the energy-to-moment ratio. It has been used to identify tsunami earthquakes, which are characterized by having unusual slow rupture velocity and release seismic energy that has been shifted to longer periods and, therefore, have low values. The slow rupture velocity would indicate weaker material and bigger uplift and, thus, bigger tsunami potential. The use of the slowness parameter is an efficient tool for monitoring the near real-time identification of tsunami earthquakes.

Rupture preparation process controlled by surface roughness on meter-scale laboratory fault

NASA Astrophysics Data System (ADS)

Yamashita, Futoshi; Fukuyama, Eiichi; Xu, Shiqing; Mizoguchi, Kazuo; Kawakata, Hironori; Takizawa, Shigeru

2018-05-01

We investigate the effect of fault surface roughness on rupture preparation characteristics using meter-scale metagabbro specimens. We repeatedly conducted the experiments with the same pair of rock specimens to make the fault surface rough. We obtained three experimental results under the same experimental conditions (6.7 MPa of normal stress and 0.01 mm/s of loading rate) but at different roughness conditions (smooth, moderately roughened, and heavily roughened). During each experiment, we observed many stick-slip events preceded by precursory slow slip. We investigated when and where slow slip initiated by using the strain gauge data processed by the Kalman filter algorithm. The observed rupture preparation processes on the smooth fault (i.e. the first experiment among the three) showed high repeatability of the spatiotemporal distributions of slow slip initiation. Local stress measurements revealed that slow slip initiated around the region where the ratio of shear to normal stress (τ/σ) was the highest as expected from finite element method (FEM) modeling. However, the exact location of slow slip initiation was where τ/σ became locally minimum, probably due to the frictional heterogeneity. In the experiment on the moderately roughened fault, some irregular events were observed, though the basic characteristics of other regular events were similar to those on the smooth fault. Local stress data revealed that the spatiotemporal characteristics of slow slip initiation and the resulting τ/σ drop for irregular events were different from those for regular ones even under similar stress conditions. On the heavily roughened fault, the location of slow slip initiation was not consistent with τ/σ anymore because of the highly heterogeneous static friction on the fault, which also decreased the repeatability of spatiotemporal distributions of slow slip initiation. These results suggest that fault surface roughness strongly controls the rupture preparation process, and generally increases its complexity with the degree of roughness.

An unified numerical simulation of seismic ground motion, ocean acoustics, coseismic deformations and tsunamis of 2011 Tohoku earthquake

NASA Astrophysics Data System (ADS)

Maeda, T.; Furumura, T.; Noguchi, S.; Takemura, S.; Iwai, K.; Lee, S.; Sakai, S.; Shinohara, M.

2011-12-01

The fault rupture of the 2011 Tohoku (Mw9.0) earthquake spread approximately 550 km by 260 km with a long source rupture duration of ~200 s. For such large earthquake with a complicated source rupture process the radiation of seismic wave from the source rupture and initiation of tsunami due to the coseismic deformation is considered to be very complicated. In order to understand such a complicated process of seismic wave, coseismic deformation and tsunami, we proposed a unified approach for total modeling of earthquake induced phenomena in a single numerical scheme based on a finite-difference method simulation (Maeda and Furumura, 2011). This simulation model solves the equation of motion of based on the linear elastic theory with equilibrium between quasi-static pressure and gravity in the water column. The height of tsunami is obtained from this simulation as a vertical displacement of ocean surface. In order to simulate seismic waves, ocean acoustics, coseismic deformations, and tsunami from the 2011 Tohoku earthquake, we assembled a high-resolution 3D heterogeneous subsurface structural model of northern Japan. The area of simulation is 1200 km x 800 km and 120 km in depth, which have been discretized with grid interval of 1 km in horizontal directions and 0.25 km in vertical direction, respectively. We adopt a source-rupture model proposed by Lee et al. (2011) which is obtained by the joint inversion of teleseismic, near-field strong motion, and coseismic deformation. For conducting such a large-scale simulation, we fully parallelized our simulation code based on a domain-partitioning procedure which achieved a good speed-up by parallel computing up to 8192 core processors with parallel efficiency of 99.839%. The simulation result demonstrates clearly the process in which the seismic wave radiates from the complicated source rupture over the fault plane and propagating in heterogeneous structure of northern Japan. Then, generation of tsunami from coseismic ground deformation at sea floor due to the earthquake and propagation is also well demonstrated . The simulation also demonstrates that a very large slip up to 40 m at shallow plate boundary near the trench pushes up sea floor with source rupture propagation, and the highly elevated sea surface gradually start propagation as tsunamis due to the gravity. The result of simulation of vertical-component displacement waveform matches the ocean-bottom pressure gauge record which is installed just above the source fault area (Maeda et al., 2011) very consistently. Strong reverberation of the ocean-acoustic waves between sea surface and sea bottom particularly near the Japan Trench for long time after the source rupture ends is confirmed in the present simulation. Accordingly, long wavetrains of high-frequency ocean acoustic waves is developed and overlap to later tsunami waveforms as we found in the observations.

The Elizabeth Lake paleoseismic site: Rupture pattern constraints for the past ~800 years for the Mojave section of the south-central San Andreas Fault

USGS Publications Warehouse

Bemis, Sean; Scharer, Katherine M.; Dolan, James F.; Rhodes, Ed

2016-01-01

The southern San Andreas Fault in California has hosted two historic surface-rupturing earthquakes, the ~M7 1812 Wrightwood earthquake and the ~M7.9 1857 Fort Tejon earthquake (e.g., Sieh, 1978; Jacoby et al., 1988). Numerous paleoseismic studies have established chronologies of historic and prehistoric earthquakes at sites along the full length of the 1857 rupture (e.g., Sieh, 1978; Scharer et al., 2014). These studies provide an unparalleled opportunity to examine patterns of recent ruptures; however, at least two significant spatial gaps in high-quality paleoseismic sites remain. At ~100 km long each, these gaps contribute up to 100 km of uncertainty to paleo-rupture lengths and could also permit a surface rupture from an earthquake up to ~M7.2 to go undetected [using scaling relationships of Wells and Coppersmith (1994)]. Given the known occurrence of an ~M7 earthquake on this portion of the SAF (1812), it is critical to fill these gaps in order to better constrain paleo-rupture lengths and to increase the probability of capturing the full spatial record of surface rupturing earthquakes.   In this study, we target a new site within the 100 km long stretch of the San Andreas Fault between the Frazier Mountain and Pallett Creek paleoseismic sites (Figure 1), near Elizabeth Lake, California. Prior excavations at the site during 1998-1999 encountered promising stratigraphy but these studies were hindered by shallow groundwater throughout the site. We began our current phase of investigations in 2012, targeting the northwestern end of a 40 x 350 m fault-parallel depression that defines the site (Figure 2). Subsequent investigations in 2013 and 2014 focused on the southeastern end of the depression where the fault trace is constrained between topographic highs and is proximal to an active drainage. In total, our paleoseismic investigations consist of 10 fault-perpendicular trenches that cross the depression (Figure 2) and expose a >2000 year depositional record. These trenches reveal that the thickest section of young stratigraphy occurs at the southeastern end of the site where the fault zone projects through an area of relatively continuous sediment accumulation from a northeast-flowing drainage. This portion of the site contains a 3-m-wide pop-up structure within the fault zone that separates alternating alluvial and paludal deposits south of the fault zone from a thick organic-rich loam on the north side of the fault zone. Faults, fissures, and tilted blocks provide evidence for 4 to 5 paleoearthquakes since ca. 1250 A.D. Radiocarbon dating established that the site has a significant component of detrital charcoal producing an age spread of up to 500 years. To supplement our age chronology we incorporated ages from collections of micro-scale organic fractions and post-IR infrared stimulated luminescence dating in order to better estimate true layer ages.

On- and off-fault coseismic surface deformation associated with the September 2013 M7.7 Balochistan, Pakistan earthquake measured from mapping and automated pixel correlation

NASA Astrophysics Data System (ADS)

Gold, R. D.; Reitman, N. G.; Briggs, R. W.; Barnhart, W. D.; Hayes, G. P.

2014-12-01

The 24 September 2013 Mw7.7 Balochistan, Pakistan earthquake ruptured a ~200 km-long stretch of the Hoshab fault in southern Pakistan. We remotely measured the coseismic surface deformation field using high-resolution (0.5 m) pre- and post-event satellite imagery. We measured ~300 near-field (0-10 m from fault) laterally offset piercing points (streams, terrace risers, roads, etc.) and find peak left-lateral offsets of ~12-15 m. We characterized the far-field (0-10 km from fault) displacement field using manual (~250 measurements) and automated image cross-correlation methods (e.g., pixel tracking) and find peak displacement values of ~16 m, which commonly exceed the on-fault displacement magnitudes. Our preliminary observations suggest the following: (1) coseismic surface displacement typically increases with distance away from the surface trace of the fault (e.g., highest displacement values in the far field), (2) for certain locations along the fault rupture, as little as 50% of the coseismic displacement field occurred in the near-field; and (3) the magnitudes of individual displacements are inversely correlated to the width of the surface rupture zone (e.g., largest displacements where the fault zone is narrowest). This analysis highlights the importance of identifying field study sites spanning fault sections with narrow deformation zones in order to capture the entire deformation field. For regions of distributed deformation, these results would predict that geologic slip rate studies underestimate a fault's complete slip rate.

Incidence of deep vein thrombosis and pulmonary embolism after Achilles tendon rupture.

PubMed

Patel, Arush; Ogawa, Brent; Charlton, Timothy; Thordarson, David

2012-01-01

The use of venous thromboembolism prophylaxis after an Achilles rupture is controversial. The rates of reported deep vein thrombosis (DVT) range from 6.3% to 34%. There is no agreement regarding prophylactic therapy after an Achilles tendon rupture. We determined the overall risk of DVT and pulmonary embolism (PE) after an Achilles tendon rupture and identified potential risk factors including surgery. We retrospectively reviewed a large healthcare management organization database and identified 1172 patients who had Achilles tendon ruptures. None of the patients routinely received anticoagulation. Patients were stratified into surgical versus nonsurgical group, age older than 40 years, history of congestive heart failure, previous history of DVT or PE, and BMI greater than 30. A patient was considered to have symptomatic DVT or PE related to the Achilles tendon rupture if diagnosed within 3 months from the injury or surgery. We used a multivariable analysis to identify risk factors. The overall rates for DVT and PE after Achilles tendon ruptures were 0.43% and 0.34%, respectively. Age older than 40 years, congestive heart failure, history of DVT or PE, obesity, and whether a patient had surgery did not predict occurrence of DVT or PE. We found the overall incidence of symptomatic DVT and PE to be low after an Achilles tendon rupture and believe routine use of anticoagulation might be unwarranted.

Earthquake geology of the Bulnay Fault (Mongolia)

USGS Publications Warehouse

Rizza, Magali; Ritz, Jean-Franciois; Prentice, Carol S.; Vassallo, Ricardo; Braucher, Regis; Larroque, Christophe; Arzhannikova, A.; Arzhanikov, S.; Mahan, Shannon; Massault, M.; Michelot, J-L.; Todbileg, M.

2015-01-01

The Bulnay earthquake of July 23, 1905 (Mw 8.3-8.5), in north-central Mongolia, is one of the world's largest recorded intracontinental earthquakes and one of four great earthquakes that occurred in the region during the 20th century. The 375-km-long surface rupture of the left-lateral, strike-slip, N095°E trending Bulnay Fault associated with this earthquake is remarkable for its pronounced expression across the landscape and for the size of features produced by previous earthquakes. Our field observations suggest that in many areas the width and geometry of the rupture zone is the result of repeated earthquakes; however, in those areas where it is possible to determine that the geomorphic features are the result of the 1905 surface rupture alone, the size of the features produced by this single earthquake are singular in comparison to most other historical strike-slip surface ruptures worldwide. Along the 80 km stretch, between 97.18°E and 98.33°E, the fault zone is characterized by several meters width and the mean left-lateral 1905 offset is 8.9 ± 0.6 m with two measured cumulative offsets that are twice the 1905 slip. These observations suggest that the displacement produced during the penultimate event was similar to the 1905 slip. Morphotectonic analyses carried out at three sites along the eastern part of the Bulnay fault, allow us to estimate a mean horizontal slip rate of 3.1 ± 1.7 mm/yr over the Late Pleistocene-Holocene period. In parallel, paleoseismological investigations show evidence for two earthquakes prior to the 1905 event with recurrence intervals of ~2700-4000 years.

The Mw6.0 24 August 2014 South Napa earthquake

USGS Publications Warehouse

Brocher, Thomas M.; Baltay, Annemarie S.; Hardebeck, Jeanne L.; Pollitz, Fred F.; Murray, Jessica R.; Llenos, Andrea L.; Schwartz, David P.; Blair, James Luke; Ponti, Daniel J.; Lienkaemper, James J.; Langenheim, V.E.; Dawson, Timothy E.; Hudnut, Kenneth W.; Shelly, David R.; Dreger, Douglas S.; Boatwright, John; Aagaard, Brad T.; Wald, David J.; Allen, Richard M.; Barnhart, William D.; Knudsen, Keith L.; Brooks, Benjamin A.; Scharer, Katherine M.

2015-01-01

The Mw 6.0 South Napa earthquake, which occurred at 10:20 UTC 24 August 2014 was the largest earthquake to strike the greater San Francisco Bay area since the Mw 6.9 1989 Loma Prieta earthquake. The rupture from this right‐lateral earthquake propagated mostly unilaterally to the north and up‐dip, directing the strongest shaking toward the city of Napa, where peak ground accelerations (PGAs) between 45%g and 61%g were recorded and modified Mercalli intensities (MMIs) of VII–VIII were reported. Tectonic surface rupture with dextral slip of up to 46 cm was observed on a 12.5 km long segment, some of which was along a previously mapped strand of the West Napa fault system, although the rupture extended to the north of the mapped Quaternary strand. Modeling of seismic and geodetic data suggests an average coseismic slip of 50 cm, with a maximum slip of about 1 m at depths of 10–11 km. We observed up to 35 cm of afterslip along the surface trace in the week following the mainshock, primarily along the southern half of the surface rupture that experienced relatively little coseismic offset. Relocation of the sparse aftershock sequence suggests en echelon southwest‐ and northeast‐dipping fault planes, reflective of the complex fault geometry in this region. The Napa basin and historic and late Holocene alluvial flood deposits in downtown Napa amplified the ground motions there. Few ground failures were mapped, reflecting the dry season (as well as a persistent drought that had lowered the groundwater table) and the short duration of strong shaking in the epicentral area.

The Surface Displacement Field of the November 8, 1997, Mw7.6 Manyi (Tibet) Earthquake Observed with ERS InSAR Data

NASA Technical Reports Server (NTRS)

Peltzer, G.; Crampe, F.

1998-01-01

ERS2 radar data acquired before and after the Mw7.6, Manyi (Tibet) earthquake of November 8, 1997, provide geodetic information about the surface displacement produced by the earthquake in two ways. (1) The sub-pixel geometric adjustment of the before and after images provides a two dimensional offset field with a resolution of approx, 1m in both the range (radar line of sight) and azimuth (satellite track) directions. Comparison of offsets in azimuth and range indicates that the displacement along the fault is essentially strike-slip and in a left-lateral sense. The offset map reveals a relatively smooth and straight, N78E surface rupture that exceeds 150 km in length, consistent with the EW plane of the Harvard CMT solution. The rupture follows the trace of a quaternary fault visible on satellite imagery (Tapponnier and Molnar, 1978; Wan Der Woerd, pers. comm.). (2) Interferometric processing of the SAR data provides a range displacement map with a precision of a few millimeters. The slip distribution along the rupture reconstructed from the range change map is a bell-shaped curve in the 100-km long central section of the fault with smaller, local maxima near both ends. The curve shows that the fault slip exceeds 2.2 m in range, or 6.2 in strike-slip, along a 30-km long section of the fault and remains above 1 m in range, approx. 3 m strike-slip, along most of its length. Preliminary forward modeling of the central section of the rupture, assuming a uniform slip distribution with depth, indicates that the slip occur-red essentially between 0 and the depth of 10 km, consistent with a relatively shallow event (Velasco et al., 1998).

Dynamic effects in friction and adhesion through cooperative rupture and formation of supramolecular bonds.

PubMed

Blass, Johanna; Albrecht, Marcel; Bozna, Bianca L; Wenz, Gerhard; Bennewitz, Roland

2015-05-07

We introduce a molecular toolkit for studying the dynamics in friction and adhesion from the single molecule level to effects of multivalency. As experimental model system we use supramolecular bonds established by the inclusion of ditopic adamantane connector molecules into two surface-bound cyclodextrin molecules, attached to a tip of an atomic force microscope (AFM) and to a flat silicon surface. The rupture force of a single bond does not depend on the pulling rate, indicating that the fast complexation kinetics of adamantane and cyclodextrin are probed in thermal equilibrium. In contrast, the pull-off force for a group of supramolecular bonds depends on the unloading rate revealing a non-equilibrium situation, an effect discussed as the combined action of multivalency and cantilever inertia effects. Friction forces exhibit a stick-slip characteristic which is explained by the cooperative rupture of groups of host-guest bonds and their rebinding. No dependence of friction on the sliding velocity has been observed in the accessible range of velocities due to fast rebinding and the negligible delay of cantilever response in AFM lateral force measurements.

Multi-Step Fibrinogen Binding to the Integrin αIIbβ3 Detected Using Force Spectroscopy

PubMed Central

Litvinov, Rustem I.; Bennett, Joel S.; Weisel, John W.; Shuman, Henry

2005-01-01

The regulated ability of integrin αIIbβ3 to bind fibrinogen plays a crucial role in platelet aggregation and hemostasis. We have developed a model system based on laser tweezers, enabling us to measure specific rupture forces needed to separate single receptor-ligand complexes. First of all, we performed a thorough and statistically representative analysis of nonspecific protein-protein binding versus specific αIIbβ3-fibrinogen interactions in combination with experimental evidence for single-molecule measurements. The rupture force distribution of purified αIIbβ3 and fibrinogen, covalently attached to underlying surfaces, ranged from ∼20 to 150 pN. This distribution could be fit with a sum of an exponential curve for weak to moderate (20–60 pN) forces, and a Gaussian curve for strong (>60 pN) rupture forces that peaked at 80–90 pN. The interactions corresponding to these rupture force regimes differed in their susceptibility to αIIbβ3 antagonists or Mn2+, an αIIbβ3 activator. Varying the surface density of fibrinogen changed the total binding probability linearly >3.5-fold but did not affect the shape of the rupture force distribution, indicating that the measurements represent single-molecule binding. The yield strength of αIIbβ3-fibrinogen interactions was independent of the loading rate (160–16,000 pN/s), whereas their binding probability markedly correlated with the duration of contact. The aggregate of data provides evidence for complex multi-step binding/unbinding pathways of αIIbβ3 and fibrinogen revealed at the single-molecule level. PMID:16040750

The mechanical implications of deep fluids in the rupture process of giant landslides

NASA Astrophysics Data System (ADS)

Cappa, Frédéric; Guglielmi, Yves; Viseur, Sophie; Garambois, Stéphane

2015-04-01

Fluids are known to be a triggering and driving factor for landslides. Hydromechanical coupling has been proposed as possible explanation for landslide dynamics, including both slow, aseismic slip, as well as fast, seismic rupture. The widely accepted understanding is that rainfall, snowmelt and the seasonality of the groundwater recharge increases fluid pressures, which in turn reduces effective stress, and thus alters the strength of rocks and rupture surfaces, promoting sliding. So far, most interpretations focused on the effects of rainfall infiltration into landslides, and did not investigate in detail the role of groundwater table variations below the landslides on the rupture processes. However, such considerations are important, since observations of well-documented giant landslides showed that the moving volume extends hundreds of meters above the slope aquifer. Furthermore, although motions correlate well with seasonal infiltrations, no significant pore pressure increase has ever been measured within the landslide body, particularly in high-permeability rocky landslides. Indeed, motions occur in the near surface of the unsaturated slope, which is in general highly permeable (which allows high infiltration rates), perched, highly discontinuous, size-limited, and experiences low magnitude pore pressure build-up that is not high enough to significantly vary the effective stresses in the slope. Triggering of local instabilities by such perched low-pressurized zones may be possible only at the critical stress level of the rock, but do not explain the slow increase in the permanent background seasonal accelerations and decelerations that affect the entire landslide. Thus, clarifying the role of fluids, especially the effects of groundwater table variations within the deep aquifer on the unsaturated slope slow rupture is important for improved understanding of weak forcing mechanisms on landslides and risk assessment. The study of strain partitioning in two giant rocky landslides in France (La Clapière and Séchilienne, estimated volume of about 60 million cubic meters) provides a unique insight into the sensitivity of landslide motions to the changes in deep fluid pressures and surface frictional properties. Here we show with hydromechanical modeling that a significant part of the observed landslide motions and associated seismicity may be caused by poroelastic strain below the landslide, induced by groundwater table variations. In the unstable volume near the surface, calculated strain and rupture may be controlled by stress transfer and friction weakening above the phreatic zone and reproduce well high-motion zone characteristics measured by geodesy and seismology. The key model parameters are friction weakening and the position of groundwater level, which is sufficiently constrained by field data and seismic imaging to support the physical validity of the model. These results are of importance for the understanding of surface strain evolution under weak forcing and they demonstrated that the seasonal variation of deep fluids below the landslide is a major increasing factor of instability.

Simulation model of an eyeball based on finite element analysis on a supercomputer

PubMed Central

Uchio, E.; Ohno, S.; Kudoh, J.; Aoki, K.; Kisielewicz, L. T.

1999-01-01

BACKGROUND/AIMS—A simulation model of the human eye was developed. It was applied to the determination of the physical and mechanical conditions of impacting foreign bodies causing intraocular foreign body (IOFB) injuries.
METHODS—Modules of the Hypermesh (Altair Engineering, Tokyo, Japan) were used for solid modelling, geometric construction, and finite element mesh creation based on information obtained from cadaver eyes. The simulations were solved by a supercomputer using the finite element analysis (FEA) program PAM-CRASH (Nihon ESI, Tokyo, Japan). It was assumed that rupture occurs at a strain of 18.0% in the cornea and 6.8% in the sclera and at a stress of 9.4 MPa for both cornea and sclera. Blunt-shaped missiles were shot and set to impact on the surface of the cornea or sclera at velocities of 30 and 60 m/s, respectively.
RESULTS—According to the simulation, the sizes of missile above which corneal rupture occurred at velocities of 30 and 60 m/s were 1.95 and 0.82 mm. The missile sizes causing scleral rupture were 0.95 and 0.75 mm at velocities of 30 and 60 m/s.
CONCLUSIONS—These results suggest that this FEA model has potential usefulness as a simulation tool for ocular injury and it may provide useful information for developing protective measures against industrial and traffic ocular injuries.

 PMID:10502567

Structural context of the 2015 pair of Nepal earthquakes (Mw 7.8 and Mw 7.3): an analysis based on slip distribution, aftershock growth, and static stress changes

NASA Astrophysics Data System (ADS)

Parameswaran, Revathy M.; Rajendran, Kusala

2017-04-01

The Great Himalayan earthquakes are believed to originate on the Main Himalayan Thrust, and their ruptures lead to deformation along the Main Frontal Thrust (MFT). The rupture of the April 25, 2015 (Mw 7.8), earthquake was east-directed, with no part relayed to the MFT. The aftershock distribution, coseismic elevation change of 1 m inferred from the InSAR image, and the spatial correspondence of the subtle surface deformations with PT2, a previously mapped out-of-sequence thrust, lead us to explore the role of structural heterogeneities in constraining the rupture progression. We used teleseismic moment inversion of P- and SH-waves, and Coulomb static stress changes to map the slip distribution, and growth of aftershock area, to understand their relation to the thrust systems. Most of the aftershocks were sourced outside the stress shadows (slip >1.65 m) of the April 25 earthquake. The May 12 (Mw 7.3) earthquake that sourced on a contiguous patch coincides with regions of increased stress change and therefore is the first known post-instrumentation example of a late, distant, and large triggered aftershock associated with any large earthquake in the Nepal Himalaya. The present study relates the slip, aftershock productivity, and triggering of unbroken stress barriers, to potential out-of-sequence thrusts, and suggests the role of stress transfer in generating large/great earthquakes.

Measuring slip in paleoearthquakes using high-resolution aerial lidar data: Combined analysis of the Wairau, Awatere, Clarence, and Hope faults, South Island, New Zealand

NASA Astrophysics Data System (ADS)

Zinke, R. W.; Dolan, J. F.; Hatem, A. E.; Van Dissen, R. J.; Langridge, R.; Grenader, J.; McGuire, C. P.; Rhodes, E. J.; Nicol, A., , Prof

2016-12-01

Analysis of a large new high-resolution aerial lidar microtopographic data set provides > 500 measured fault offsets from sections of the four primary right-lateral strike-slip faults of the Marlborough Fault System (MFS), in northern South Island, New Zealand. With a shot density of >12 shots/m2 (and locally up to 18 shots/m2) these high-quality data allow us to resolve topographically defined geomorphic offsets with decimeter precision along 250 km of combined fault length. The measured offsets range in size from 2 m to > 100 m, and allow us to constrain displacements in the past one to several surface ruptures along stretches of the Wairau, Awatere, Clarence, and Hope faults. Our results reveal a number of important details of the rupture history of these faults, including: (1) the amount of slip and spatial variability (along and across strike) of strain released in the most recent event along sections of each of the four faults; (2) the consistency of slip throughout the past several ruptures on specific faults; and (3) suggestions of potential linkages and segment boundaries along each fault. The lidar data also facilitate precise measurements of larger offsets that, when combined with age data collected as part of our broader collaborative analyses of incremental fault slip rates and paleoearthquake ages, help to constrain the broader spatial and temporal patterns of strain release across the MFS during Holocene and latest Pleistocene time.

Rupture history of the 2008 Mw 7.9 Wenchuan, China, earthquake: Evaluation of separate and joint inversions of geodetic, teleseismic, and strong-motion data

USGS Publications Warehouse

Hartzell, Stephen; Mendoza, Carlos; Ramírez-Guzmán, Leonardo; Zeng, Yuesha; Mooney, Walter

2013-01-01

An extensive data set of teleseismic and strong-motion waveforms and geodetic offsets is used to study the rupture history of the 2008 Wenchuan, China, earthquake. A linear multiple-time-window approach is used to parameterize the rupture. Because of the complexity of the Wenchuan faulting, three separate planes are used to represent the rupturing surfaces. This earthquake clearly demonstrates the strengths and limitations of geodetic, teleseismic, and strong-motion data sets. Geodetic data (static offsets) are valuable for determining the distribution of shallower slip but are insensitive to deeper faulting and reveal nothing about the timing of slip. Teleseismic data in the distance range 30°–90° generally involve no modeling difficulties because of simple ray paths and can distinguish shallow from deep slip. Teleseismic data, however, cannot distinguish between different slip scenarios when multiple fault planes are involved because steep takeoff angles lead to ambiguity in timing. Local strong-motion data, on the other hand, are ideal for determining the direction of rupture from directivity but can easily be over modeled with inaccurate Green’s functions, leading to misinterpretation of the slip distribution. We show that all three data sets are required to give an accurate description of the Wenchuan rupture. The moment is estimated to be approximately 1.0 × 1021 N · m with the slip characterized by multiple large patches with slips up to 10 m. Rupture initiates on the southern end of the Pengguan fault and proceeds unilaterally to the northeast. Upon reaching the cross-cutting Xiaoyudong fault, rupture of the adjacent Beichuan fault starts at this juncture and proceeds bilaterally to the northeast and southwest.

Earthquake rupture dynamics in poorly lithified sediments

NASA Astrophysics Data System (ADS)

De Paola, N.; Bullock, R. J.; Holdsworth, R.; Marco, S.; Nielsen, S. B.

2017-12-01

Several recent large earthquakes have generated anomalously large slip patches when propagating through fluid-saturated, clay-rich sediments near the surface. Friction experiments at seismic slip rates show that such sediments are extremely weak and deform with very little energy dissipation, which facilitates rupture propagation. Although dynamic weakening may explain the ease of rupture propagation through such sediments, it cannot account for the peculiar slow rupture velocity and low radiation efficiency exhibited by some large, shallow ruptures. Here, we integrate field and experimental datasets to describe on- and off-fault deformation in natural syn-depositional seismogenic faults (< 35 ka) in shallow, clay-rich, poorly lithified sediments from the Dead Sea Fault system, Israel. The data are then used to estimate the energy dissipated by on- and off-fault damage during earthquake rupture through shallow, clay-rich sediments. Our mechanical and field data show localised principal slip zones (PSZs) that deform by particulate flow, with little energy dissipated by brittle fracturing with cataclasis. Conversely, we show that coseismic brittle and ductile deformation in the damage zones outwith the PSZ, which cannot be replicated in small-scale laboratory experiments, is a significant energy sink, contributing to an energy dissipation that is one order of magnitude greater than that estimated from laboratory experiments alone. In particular, a greater proportion of dissipated energy would result in lower radiation efficiency, due to a reduced proportion of radiated energy, plus slower rupture velocity and more energy radiation in the low frequency range than might be anticipated from laboratory experiments alone. This result is in better agreement with seismological estimates of fracture energy, implying that off-fault damage can account for the geophysical characteristics of earthquake ruptures as they pass through clay-rich sediments in the shallow crust.

Kinematic and Dynamic Source Rupture Scenario for Potential Megathrust Event along the Southernmost Ryukyu Trench

NASA Astrophysics Data System (ADS)

Lin, T. C.; Hu, F.; Chen, X.; Lee, S. J.; Hung, S. H.

2017-12-01

Kinematic source model is widely used for the simulation of an earthquake, because of its simplicity and ease of application. On the other hand, dynamic source model is a more complex but important tool that can help us to understand the physics of earthquake initiation, propagation, and healing. In this study, we focus on the southernmost Ryukyu Trench which is extremely close to northern Taiwan. Interseismic GPS data in northeast Taiwan shows a pattern of strain accumulation, which suggests the maximum magnitude of a potential future earthquake in this area is probably about magnitude 8.7. We develop dynamic rupture models for the hazard estimation of the potential megathrust event based on the kinematic rupture scenarios which are inverted using the interseismic GPS data. Besides, several kinematic source rupture scenarios with different characterized slip patterns are also considered to constrain the dynamic rupture process better. The initial stresses and friction properties are tested using the trial-and-error method, together with the plate coupling and tectonic features. An analysis of the dynamic stress field associated with the slip prescribed in the kinematic models can indicate possible inconsistencies with physics of faulting. Furthermore, the dynamic and kinematic rupture models are considered to simulate the ground shaking from based on 3-D spectral-element method. We analyze ShakeMap and ShakeMovie from the simulation results to evaluate the influence over the island between different source models. A dispersive tsunami-propagation simulation is also carried out to evaluate the maximum tsunami wave height along the coastal areas of Taiwan due to coseismic seafloor deformation of different source models. The results of this numerical simulation study can provide a physically-based information of megathrust earthquake scenario for the emergency response agency to take the appropriate action before the really big one happens.

Late Pleistocene - Holocene ruptures of the Lima Reservoir fault, SW Montana

NASA Astrophysics Data System (ADS)

Anastasio, David J.; Majerowicz, Christina N.; Pazzaglia, Frank J.; Regalla, Christine A.

2010-12-01

Active tectonics within the northern Basin and Range province provide a natural laboratory for the study of normal fault growth, linkage, and interaction. Here, we present new geologic mapping and morphologic fault-scarp modeling within the Centennial Valley, Montana to characterize Pleistocene - Holocene ruptures of the young and active Lima Reservoir fault. Geologic relationships and rupture ages indicate Middle Pleistocene activity on the Henry Gulch (>50 ka and 23-10 ka), Trail Creek (>43 ka and ˜13 ka), and reservoir (˜23 ka) segments. Offset Quaternary deposits also record Holocene rupture of the reservoir segment (˜8 ka), but unfaulted modern streams show that no segments of the Lima Reservoir fault have experienced a large earthquake in at least several millennia. The clustered pattern of rupture ages on the Lima Reservoir fault segments suggests a seismogenic linkage though segment length and spacing make a physical connection at depth unlikely. Trail Creek and reservoir segment slip rates were non-steady and appear to be increasing. The fault helps accommodate differential horizontal surface velocity measured by GPS geodesy across the boundary between the northern Basin and Range province and the Snake River Plain.

Diverse rupture modes for surface-deforming upper plate earthquakes in the southern Puget Lowland of Washington State

USGS Publications Warehouse

Nelson, Alan R.; Personius, Stephen F.; Sherrod, Brian L.; Kelsey, Harvey M.; Johnson, Samuel Y.; Bradley, Lee-Ann; Wells, Ray E.

2014-01-01

Earthquake prehistory of the southern Puget Lowland, in the north-south compressive regime of the migrating Cascadia forearc, reflects diverse earthquake rupture modes with variable recurrence. Stratigraphy and Bayesian analyses of previously reported and new 14C ages in trenches and cores along backthrust scarps in the Seattle fault zone restrict a large earthquake to 1040–910 cal yr B.P. (2σ), an interval that includes the time of the M 7–7.5 Restoration Point earthquake. A newly identified surface-rupturing earthquake along the Waterman Point backthrust dates to 940–380 cal yr B.P., bringing the number of earthquakes in the Seattle fault zone in the past 3500 yr to 4 or 5. Whether scarps record earthquakes of moderate (M 5.5–6.0) or large (M 6.5–7.0) magnitude, backthrusts of the Seattle fault zone may slip during moderate to large earthquakes every few hundred years for periods of 1000–2000 yr, and then not slip for periods of at least several thousands of years. Four new fault scarp trenches in the Tacoma fault zone show evidence of late Holocene folding and faulting about the time of a large earthquake or earthquakes inferred from widespread coseismic subsidence ca. 1000 cal yr B.P.; 12 ages from 8 sites in the Tacoma fault zone limit the earthquakes to 1050–980 cal yr B.P. Evidence is too sparse to determine whether a large earthquake was closely predated or postdated by other earthquakes in the Tacoma basin, but the scarp of the Tacoma fault was formed by multiple earthquakes. In the northeast-striking Saddle Mountain deformation zone, along the western limit of the Seattle and Tacoma fault zones, analysis of previous ages limits earthquakes to 1200–310 cal yr B.P. The prehistory clarifies earthquake clustering in the central Puget Lowland, but cannot resolve potential structural links among the three Holocene fault zones.

Rapid Response Products of The ARIA Project for the M6.0 August 24, 2014 South Napa Earthquake

NASA Astrophysics Data System (ADS)

Yun, S. H.; Owen, S. E.; Hua, H.; Milillo, P.; Fielding, E. J.; Hudnut, K. W.; Dawson, T. E.; Mccrink, T. P.; Jo, M. J.; Barnhart, W. D.; Manipon, G. J. M.; Agram, P. S.; Moore, A. W.; Jung, H. S.; Webb, F.; Milillo, G.; Rosinski, A.

2014-12-01

A magnitude 6.0 earthquake struck southern Napa county northeast of San Francisco, California, on Aug. 24, 2014, causing significant damage in the city of Napa and nearby areas. One day after the earthquake, the Advanced Rapid Imaging and Analysis (ARIA) team produced and released observations of coseismic ground displacement measured with continuous GPS stations of the Plate Boundary Observatory (operated by UNAVCO for the National Science Foundation) and the Bay Area Rapid Deformation network (operated by Berkeley Seismological Laboratory). Three days after the earthquake (Aug. 27), the Italian Space Agency's (ASI) COSMO-SkyMed (CSK) satellite acquired their first post-event data. On the same day, the ARIA team, in collaboration with ASI and University of Basilicata, produced and released a coseismic interferogram that revealed ground deformation and surface rupture. The depiction of the surface rupture - discontinuities of color fringes in the CSK interferogram - helped guide field geologists from the US Geological Survey and the California Geological Survey (CGS) to features that may have otherwise gone undetected. Small-scale cracks were found on a runway of the Napa County Airport, as well as bridge damage and damaged roads. ARIA's response to this event highlighted the importance of timeliness for mapping surface deformation features. ARIA's rapid response products were shared through Southern California Earthquake Center's response website and the California Earthquake Clearinghouse. A damage proxy map derived from InSAR coherence of CSK data was produced and distributed on Aug. 27. Field crews from the CGS identified true and false positives, including mobile home damage, newly planted grape vines, and a cripple wall failure of a house. Finite fault slip models constrained from CSK interferograms and continuous GPS observations reveal a north-propagating rupture with well-resolved slip from 0-10.5 km depth. We also measured along-track coseismic displacements of about -30 to 30 cm, along the main surface rupture, using multiple aperture interferometry and SAR pixel offset calculation. We also processed the European Space Agency's Sentinel-1A data on Sep. 3 and compared the result with the CSK interferogram, finding a general agreement between the two observations of surface deformation.

Large-Scale Biaxial Friction Experiments with an Assistance of the NIED Shaking Table

NASA Astrophysics Data System (ADS)

Fukuyama, E.; Mizoguchi, K.; Yamashita, F.; Togo, T.; Kawakata, H.; Yoshimitsu, N.; Shimamoto, T.; Mikoshiba, T.; Sato, M.; Minowa, C.

2012-12-01

We constructed a large-scale biaxial friction apparatus using a large shaking table working at NIED (table dimension is 15m x 15m). The actuator of the shaking table becomes the engine of the constant speed loading. We used a 1.5m long rock sample overlaid on a 2m one. Their height and width are both 0.5m. Therefore, the slip area is 1.5m x 0.5m. The 2m long sample moves with the shaking table and the 1.5m sample is fixed to the basement of the shaking table. Thus, the shaking table displacement controls the dislocation between two rock samples. The shaking table can generate 0.4m displacement with a velocity ranging between 0.0125mm/s and 1m/s. We used Indian gabbro for the rock sample of the present experiments. Original flatness of the sliding surface was formed less than 0.024mm undulation using a large-scale plane grinder. Surface roughness evolved as subsequent experiments were done. Wear material was generated during each experiment, whose grain size becomes bigger as the experiments proceed. This might suggest a damage evolution on the sliding surface. In some experiments we did not remove the gouge material before sliding to examine the effect of gouge layer. Normal stress can be applied up to 1.3MPa. The stiffness of this apparatus was measured experimentally and was of the order of 0.1GN/m. We first measured the coefficient of friction at low sliding velocity (0.1~1mm/s) where the steady state was achieved after the slip of ~5mm. The coefficient of friction was about 0.75 under the normal stress between 0.13 and 1.3MPa. This is consistent with those estimated by previous works using smaller rock samples. We observed that the coefficient of friction decreased gradually with increasing slip velocity, but simultaneously the friction curves at the higher velocities are characterized by stick-slip vibration. Our main aim of the experiments is to understand the rupture propagation from slow nucleation to fast unstable rupture during the loading of two contact surfaces. We recorded many unstable slip events that nucleated inside the sliding surface but did not reach the edge of the sliding surface until the termination of slip. These slip events simulate full rupture process during earthquake, including nucleation, propagation and termination of the rupture. We monitored these rupture progress using the strain change propagation measured by 16 semiconductor strain gauges recorded at a sampling rate of 1MHz. In addition, high frequency waves emitted from AE events was continuously observed by 8 piezo-electronic transducers (PZTs) at a sampling rate of 20MHz. These sensors were attached at the edge of the slipping area. The AE event started to occur where the slip was nucleated and the slip area started to expand. Unfortunately, we could not locate all AE events during the unstable rupture, because of the overprints of signals from multiple events in the PZT records. We also monitored the amplitudes of transmitted waves across the sliding surface. The amplitudes decreased just after the stick slip and recovered gradually, suggesting that the transmitted wave amplitudes might reflect the slipped area on the interface.

Complex multifault rupture during the 2016 Mw 7.8 Kaikōura earthquake, New Zealand.

PubMed

Hamling, Ian J; Hreinsdóttir, Sigrún; Clark, Kate; Elliott, John; Liang, Cunren; Fielding, Eric; Litchfield, Nicola; Villamor, Pilar; Wallace, Laura; Wright, Tim J; D'Anastasio, Elisabetta; Bannister, Stephen; Burbidge, David; Denys, Paul; Gentle, Paula; Howarth, Jamie; Mueller, Christof; Palmer, Neville; Pearson, Chris; Power, William; Barnes, Philip; Barrell, David J A; Van Dissen, Russ; Langridge, Robert; Little, Tim; Nicol, Andrew; Pettinga, Jarg; Rowland, Julie; Stirling, Mark

2017-04-14

On 14 November 2016, northeastern South Island of New Zealand was struck by a major moment magnitude ( M w ) 7.8 earthquake. Field observations, in conjunction with interferometric synthetic aperture radar, Global Positioning System, and seismology data, reveal this to be one of the most complex earthquakes ever recorded. The rupture propagated northward for more than 170 kilometers along both mapped and unmapped faults before continuing offshore at the island's northeastern extent. Geodetic and field observations reveal surface ruptures along at least 12 major faults, including possible slip along the southern Hikurangi subduction interface; extensive uplift along much of the coastline; and widespread anelastic deformation, including the ~8-meter uplift of a fault-bounded block. This complex earthquake defies many conventional assumptions about the degree to which earthquake ruptures are controlled by fault segmentation and should motivate reevaluation of these issues in seismic hazard models. Copyright © 2017, American Association for the Advancement of Science.

Geotechnical reconnaissance of the 2002 Denali fault, Alaska, earthquake

USGS Publications Warehouse

Kayen, R.; Thompson, E.; Minasian, D.; Moss, R.E.S.; Collins, B.D.; Sitar, N.; Dreger, D.; Carver, G.

2004-01-01

The 2002 M7.9 Denali fault earthquake resulted in 340 km of ruptures along three separate faults, causing widespread liquefaction in the fluvial deposits of the alpine valleys of the Alaska Range and eastern lowlands of the Tanana River. Areas affected by liquefaction are largely confined to Holocene alluvial deposits, man-made embankments, and backfills. Liquefaction damage, sparse surrounding the fault rupture in the western region, was abundant and severe on the eastern rivers: the Robertson, Slana, Tok, Chisana, Nabesna and Tanana Rivers. Synthetic seismograms from a kinematic source model suggest that the eastern region of the rupture zone had elevated strong-motion levels due to rupture directivity, supporting observations of elevated geotechnical damage. We use augered soil samples and shear-wave velocity profiles made with a portable apparatus for the spectral analysis of surface waves (SASW) to characterize soil properties and stiffness at liquefaction sites and three trans-Alaska pipeline pump station accelerometer locations. ?? 2004, Earthquake Engineering Research Institute.

Field Investigation of Surface Deformation Induced by the 2016 Meinong Earthquake and its Implications to Regional Geological Structures

NASA Astrophysics Data System (ADS)

Yi, De-Cheng; Chuang, Ray Y.; Lin, Ching-Weei

2017-04-01

We demonstrate mapping results of a newly-identified active folding-associated fault in southwestern Taiwan, which was triggered by the distant ML 6.6 Meinong earthquake in 2016. The 14.6-km-deep main shock occurred in Meinong at 3:57 (GMT +08) on February 6th while a series of 21-27 km deep aftershocks were induced after 160 seconds in Guanmiao, where is 25km NW away from the epicenter of the main shock. The focal mechanism of the Meinong main shock shows a westward oblique thrust with the fault plane of 275°/42°/17° (strike/dip/rake) but Guanmiao aftershocks show the N-S striking eastward normal movement. The study area locates at an on-going fold-and-thrust belt close to the deformation front of Taiwan orogeny with high rates of convergence, uplift and erosion. The geology of SW Taiwan is characterized by the 3-km-thick mudstones with high fluid pressure underlying the loose sedimentary rocks forming mud diapirs or mud-core anticlines. The significance of the Meinong earthquake is (1) aftershocks are far away from the main shock, and (2) the surface cracks partially distributed systematically along lineaments observed from InSAR, which has never been recognized as geological structures before. This study aims to establish possible kinematic processes of shallow deformation induced by the Meinong earthquake. We mapped surface cracks around the lineaments by using hand-held GPS and measured surface cracks by the compass and vernier. Among 249 kinematic data measured from 244 observed surface cracks and ruptures, the type of deformation was mostly identified as dilation or lateral translation and only 4 data were compressional deformation. The overall surface displacement moved to the northwest and west, consistent with the regional coseismic movement. The opening of the surface cracks range from 0.5 to 105 mm and 85% of them are less than 10 mm. Preseismic deformed features such as failure of the retaining wall were also observed along the western and eastern boundary of the coseismic deformation area, indicating accumulated deformation and repeated structural activity in this area. In addition, we found a series of centimeters to meters long, N-S to N-W striking and eastern-side-down surface ruptures with the 4-19 cm heave distributed along the 4-km-long, nearly N-S striking and range-facing scarp with the 4-12 m height at the west of Guanmiao, where locate between the Chungchou anticline and Guanmiao syncline. We interpret these surface ruptures as a sign of the bending-moment fault associated with folding amplified by seismic energy through fluid-rich mud diapirs. Thus, seismic potential in this region needs to be re-evaluated, and the mechanism of seismic-induced amplification through high fluid pressure medium may play a critical role in assessing earthquake hazards in regions with similar geology to SW Taiwan.

Nucleation and dynamic rupture on weakly stressed faults sustained by thermal pressurization

NASA Astrophysics Data System (ADS)

Schmitt, Stuart V.; Segall, Paul; Dunham, Eric M.

2015-11-01

Earthquake nucleation requires that the shear stress τ locally reaches a fault's static strength, fσeff, the product of the friction coefficient and effective normal stress. Once rupture initiates, shear heating-induced thermal pressurization can sustain rupture at much lower τ/σeff ratios, a stress condition believed to be the case during most earthquakes. This requires that earthquakes nucleate at heterogeneities. We model nucleation and dynamic rupture on faults in a 2-D elastic medium with rate/state friction and thermal pressurization, subjected to globally low τ but with local stress heterogeneities that permit nucleation. We examine end-member cases of either high-τ or low-σeff heterogeneities. We find that thermal pressurization can sustain slip at τ/σeff values as low as 0.13, compared to static friction of ˜0.7. Background τ (and, to lesser extent, heterogeneity width) controls whether ruptures arrest or are sustained, with extremely low values resulting in arrest. For a small range of background τ, sustained slip is pulse-like. Cessation of slip in a pulse tail can result from either diffusive restrengthening of σeff or a wave-mediated stopping phase that follows the rupture tip. Slightly larger background τ leads to sustained crack-like rupture. Thermal pressurization is stronger at high-τ heterogeneities, resulting in a lower background τ threshold for sustained rupture and potentially larger arresting ruptures. High-stress events also initiate with higher moment rate, although this may be difficult to observe in nature. For arresting ruptures, stress drops and the dependence of fracture energy on mean slip are both consistent with values inferred for small earthquakes.

Presence of Bacteria in Spontaneous Achilles Tendon Ruptures.

PubMed

Rolf, Christer G; Fu, Sai-Chuen; Hopkins, Chelsea; Luan, Ju; Ip, Margaret; Yung, Shu-Hang; Friman, Göran; Qin, Ling; Chan, Kai-Ming

2017-07-01

The structural pathology of Achilles tendon (AT) ruptures resembles tendinopathy, but the causes remain unknown. Recently, a number of diseases were found to be attributed to bacterial infections, resulting in low-grade inflammation and progressive matrix disturbance. The authors speculate that spontaneous AT ruptures may also be influenced by the presence of bacteria. Bacteria are present in ruptured ATs but not in healthy tendons. Cross-sectional study; Level of evidence, 3. Patients with spontaneous AT ruptures and patients undergoing anterior cruciate ligament (ACL) reconstruction were recruited for this study. During AT surgical repair, excised tendinopathic tissue was collected, and healthy tendon samples were obtained as controls from hamstring tendon grafts used in ACL reconstruction. Half of every sample was reserved for DNA extraction and the other half for histology. Polymerase chain reaction (PCR) was conducted using 16S rRNA gene universal primers, and the PCR products were sequenced for the identification of bacterial species. A histological examination was performed to compare tendinopathic changes in the case and control samples. Five of 20 AT rupture samples were positive for the presence of bacterial DNA, while none of the 23 hamstring tendon samples were positive. Sterile operating and experimental conditions and tests on samples, controlling for harvesting and processing procedures, ruled out the chance of postoperative bacterial contamination. The species identified predominantly belonged to the Staphylococcus genus. AT rupture samples exhibited histopathological features characteristic of tendinopathy, and most healthy hamstring tendon samples displayed normal tendon features. There were no apparent differences in histopathology between the bacterial DNA-positive and bacterial DNA-negative AT rupture samples. The authors have demonstrated the presence of bacterial DNA in ruptured AT samples. It may suggest the potential involvement of bacteria in spontaneous AT ruptures.

High-resolution lidar topography of the Puget Lowland, Washington - A bonanza for earth science

USGS Publications Warehouse

Haugerud, R.A.; Harding, D.J.; Johnson, S.Y.; Harless, J.L.; Weaver, C.S.; Sherrod, B.L.

2003-01-01

More than 10,000 km2 of high-resolution, public-domain topography acquired by the Puget Sound Lidar Consortium is revolutionizing investigations of active faulting, continental glaciation, landslides, and surficial processes in the seismically active Puget Lowland. The Lowland-the population and economic center of the Pacific Northwest-presents special problems for hazards investigations, with its young glacial topography, dense forest cover, and urbanization. Lidar mapping during leaf-off conditions has led to a detailed digital model of the landscape beneath the forest canopy. The surface thus revealed contains a rich and diverse record of previously unknown surface-rupturing faults, deep-seated landslides, uplifted Holocene and Pleistocene beaches, and subglacial and periglacial features. More than half a dozen suspected postglacial fault scarps have been identified to date. Five scarps that have been trenched show evidence of large, Holocene, surface-rupturing earthquakes.

Earthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture

PubMed Central

Dixon, Timothy H.; Jiang, Yan; Malservisi, Rocco; McCaffrey, Robert; Voss, Nicholas; Protti, Marino; Gonzalez, Victor

2014-01-01

The 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr–Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential. PMID:25404327

Earthquake and tsunami forecasts: relation of slow slip events to subsequent earthquake rupture.

PubMed

Dixon, Timothy H; Jiang, Yan; Malservisi, Rocco; McCaffrey, Robert; Voss, Nicholas; Protti, Marino; Gonzalez, Victor

2014-12-02

The 5 September 2012 M(w) 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr-Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential.

Alcohol Consumption and Aneurysmal Subarachnoid Hemorrhage.

PubMed

Can, Anil; Castro, Victor M; Ozdemir, Yildirim H; Dagen, Sarajune; Dligach, Dmitriy; Finan, Sean; Yu, Sheng; Gainer, Vivian; Shadick, Nancy A; Savova, Guergana; Murphy, Shawn; Cai, Tianxi; Weiss, Scott T; Du, Rose

2018-02-01

Alcohol consumption may be a modifiable risk factor for rupture of intracranial aneurysms. Our aim is to evaluate the association between ruptured aneurysms and alcohol consumption, intensity, and cessation. The medical records of 4701 patients with 6411 radiographically confirmed intracranial aneurysms diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 were reviewed. Individuals were divided into cases with ruptured aneurysms and controls with unruptured aneurysms. Univariable and multivariable logistic regression analyses were performed to determine the association between alcohol consumption and rupture of intracranial aneurysms. In multivariable analysis, current alcohol use (OR 1.36, 95% CI 1.17-1.58) was associated with rupture status compared with never drinkers, whereas former alcohol use was not significant (OR 1.23, 95% CI 0.92-1.63). In addition, the number of alcoholic beverages per day among current alcohol users (OR 1.13, 95% CI 1.04-1.23) was significantly associated with rupture status, whereas alcohol use intensity was not significant among former users (OR 1.02, 95% CI 0.94-1.11). Current alcohol use and intensity are significantly associated with intracranial aneurysm rupture. However, this increased risk does not persist in former alcohol users, emphasizing the potential importance of alcohol cessation in patients harboring unruptured aneurysms.

Seismic constraints on the architecture of the Newport-Inglewood/Rose Canyon fault: Implications for the length and magnitude of future earthquake ruptures

NASA Astrophysics Data System (ADS)

Sahakian, Valerie; Bormann, Jayne; Driscoll, Neal; Harding, Alistair; Kent, Graham; Wesnousky, Steve

2017-03-01

The Newport-Inglewood/Rose Canyon (NIRC) fault zone is an active strike-slip fault system within the Pacific-North American plate boundary in Southern California, located in close proximity to populated regions of San Diego, Orange, and Los Angeles counties. Prior to this study, the NIRC fault zone's continuity and geometry were not well constrained. Nested marine seismic reflection data with different vertical resolutions are employed to characterize the offshore fault architecture. Four main fault strands are identified offshore, separated by three main stepovers along strike, all of which are 2 km or less in width. Empirical studies of historical ruptures worldwide show that earthquakes have ruptured through stepovers with this offset. Models of Coulomb stress change along the fault zone are presented to examine the potential extent of future earthquake ruptures on the fault zone, which appear to be dependent on the location of rupture initiation and fault geometry at the stepovers. These modeling results show that the southernmost stepover between the La Jolla and Torrey Pines fault strands may act as an inhibitor to throughgoing rupture due to the stepover width and change in fault geometry across the stepover; however, these results still suggest that rupture along the entire fault zone is possible.

Dynamic rupture modeling of the transition from thrust to strike-slip motion in the 2002 Denali fault earthquake, Alaska

USGS Publications Warehouse

Aagaard, Brad T.; Anderson, G.; Hudnut, K.W.

2004-01-01

We use three-dimensional dynamic (spontaneous) rupture models to investigate the nearly simultaneous ruptures of the Susitna Glacier thrust fault and the Denali strike-slip fault. With the 1957 Mw 8.3 Gobi-Altay, Mongolia, earthquake as the only other well-documented case of significant, nearly simultaneous rupture of both thrust and strike-slip faults, this feature of the 2002 Denali fault earthquake provides a unique opportunity to investigate the mechanisms responsible for development of these large, complex events. We find that the geometry of the faults and the orientation of the regional stress field caused slip on the Susitna Glacier fault to load the Denali fault. Several different stress orientations with oblique right-lateral motion on the Susitna Glacier fault replicate the triggering of rupture on the Denali fault about 10 sec after the rupture nucleates on the Susitna Glacier fault. However, generating slip directions compatible with measured surface offsets and kinematic source inversions requires perturbing the stress orientation from that determined with focal mechanisms of regional events. Adjusting the vertical component of the principal stress tensor for the regional stress field so that it is more consistent with a mixture of strike-slip and reverse faulting significantly improves the fit of the slip-rake angles to the data. Rotating the maximum horizontal compressive stress direction westward appears to improve the fit even further.

Transpressional Rupture Cascade of the 2016 Mw 7.8 Kaikoura Earthquake, New Zealand

NASA Astrophysics Data System (ADS)

Xu, Wenbin; Feng, Guangcai; Meng, Lingsen; Zhang, Ailin; Ampuero, Jean Paul; Bürgmann, Roland; Fang, Lihua

2018-03-01

Large earthquakes often do not occur on a simple planar fault but involve rupture of multiple geometrically complex faults. The 2016 Mw 7.8 Kaikoura earthquake, New Zealand, involved the rupture of at least 21 faults, propagating from southwest to northeast for about 180 km. Here we combine space geodesy and seismology techniques to study subsurface fault geometry, slip distribution, and the kinematics of the rupture. Our finite-fault slip model indicates that the fault motion changes from predominantly right-lateral slip near the epicenter to transpressional slip in the northeast with a maximum coseismic surface displacement of about 10 m near the intersection between the Kekerengu and Papatea faults. Teleseismic back projection imaging shows that rupture speed was overall slow (1.4 km/s) but faster on individual fault segments (approximately 2 km/s) and that the conjugate, oblique-reverse, north striking faults released the largest high-frequency energy. We show that the linking Conway-Charwell faults aided in propagation of rupture across the step over from the Humps fault zone to the Hope fault. Fault slip cascaded along the Jordan Thrust, Kekerengu, and Needles faults, causing stress perturbations that activated two major conjugate faults, the Hundalee and Papatea faults. Our results shed important light on the study of earthquakes and seismic hazard evaluation in geometrically complex fault systems.

Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea

USGS Publications Warehouse

Brothers, Daniel; Kilb, Debi; Luttrell, Karen; Driscoll, Neal W.; Kent, Graham

2011-01-01

The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger a large earthquake. The southern San Andreas fault terminates in an extensional stepover zone beneath the Salton Sea—a lake that has experienced periodic flooding and desiccation since the late Holocene. Here we reconstruct the magnitude and timing of fault activity beneath the Salton Sea over several earthquake cycles. We observe coincident timing between flooding events, stepover fault displacement and ruptures on the San Andreas fault. Using Coulomb stress models, we show that the combined effect of lake loading, stepover fault movement and increased pore pressure could increase stress on the southern San Andreas fault to levels sufficient to induce failure. We conclude that rupture of the stepover faults, caused by periodic flooding of the palaeo-Salton Sea and by tectonic forcing, had the potential to trigger earthquake rupture on the southern San Andreas fault. Extensional stepover zones are highly susceptible to rapid stress loading and thus the Salton Sea may be a nucleation point for large ruptures on the southern San Andreas fault.

Stress drop inferred from dynamic rupture simulations consistent with Moment-Rupture area empirical scaling models: Effects of week shallow zone

NASA Astrophysics Data System (ADS)

Dalguer, L. A.; Miyake, H.; Irikura, K.; Wu, H., Sr.

2016-12-01

Empirical scaling models of seismic moment and rupture area provide constraints to parameterize source parameters, such as stress drop, for numerical simulations of ground motion. There are several scaling models published in the literature. The effect of the finite width seismogenic zone and the free-surface have been attributed to cause the breaking of the well know self-similar scaling (e.g. Dalguer et al, 2008) given origin to the so called L and W models for large faults. These models imply the existence of three-stage scaling relationship between seismic moment and rupture area (e.g. Irikura and Miyake, 2011). In this paper we extend the work done by Dalguer et al 2008, in which these authors calibrated fault models that match the observations showing that the average stress drop is independent of earthquake size for buried earthquakes, but scale dependent for surface-rupturing earthquakes. Here we have developed additional sets of dynamic rupture models for vertical strike slip faults to evaluate the effect of the weak shallow layer (WSL) zone for the calibration of stress drop. Rupture in the WSL zone is expected to operate with enhanced energy absorption mechanism. The set of dynamic models consists of fault models with width 20km and fault length L=20km, 40km, 60km, 80km, 100km, 120km, 200km, 300km and 400km and average stress drop values of 2.0MPa, 2.5MPa, 3.0MPa, 3.5MPa, 5.0MPa and 7.5MPa. For models that break the free-surface, the WSL zone is modeled assuming a 2km width with stress drop 0.0MPa or -2.0 MPa. Our results show that depending on the characterization of the WSL zone, the average stress drop at the seismogenic zone that fit the empirical models changes. If WSL zone is not considered, that is, stress drop at SL zone is the same as the seismogenic zone, average stress drop is about 20% smaller than models with WSL zone. By introducing more energy absorption at the SL zone, that could be the case of large mature faults, the average stress drop in the seismogenic zone increases. Suggesting that large earthquakes need higher stress drop to break the fault than buried and moderate earthquakes. Therefore, the value of the average stress drop for large events that break the free-source depend on the definition of the WSL. Suggesting that the WSL plays an important role on the prediction of final slip and fault displacement.

Co- and post-seismic shallow fault physics from near-field geodesy, seismic tomography, and mechanical modeling

NASA Astrophysics Data System (ADS)

Nevitt, J.; Brooks, B. A.; Catchings, R.; Goldman, M.; Criley, C.; Chan, J. H.; Glennie, C. L.; Ericksen, T. L.; Madugo, C. M.

2017-12-01

The physics governing near-surface fault slip and deformation are largely unknown, introducing significant uncertainty into seismic hazard models. Here we combine near-field measurements of surface deformation from the 2014 M6.0 South Napa earthquake with high-resolution seismic imaging and finite element models to investigate the effects of rupture speed, elastic heterogeneities, and plasticity on shallow faulting. We focus on two sites that experienced either predominantly co-seismic or post-seismic slip. We measured surface deformation with mobile laser scanning of deformed vine rows within 300 m of the fault at 1 week and 1 month after the event. Shear strain profiles for the co- and post-seismic sites are similar, with maxima of 0.012 and 0.013 and values exceeding 0.002 occurring within 26 m- and 18 m-wide zones, respectively. That the rupture remained buried at the two sites and produced similar deformation fields suggests that permanent deformation due to dynamic stresses did not differ significantly from the quasi-static case, which might be expected if the rupture decelerated as it approached the surface. Active-source seismic surveys, 120 m in length with 1 m geophone/shot spacing, reveal shallow compliant zones of reduced shear modulus. For the co- and post-seismic sites, the tomographic anomaly (Vp/Vs > 5) at 20 m depth has a width of 80 m and 50 m, respectively, much wider than the observed surface displacement fields. We investigate this discrepancy with a suite of finite element models in which a planar fault is buried 5 m below the surface. The model continuum is defined by either homogeneous or heterogeneous elastic properties, with or without Drucker-Prager plastic yielding, with properties derived from lab testing of similar near-surface materials. We find that plastic yielding can greatly narrow the surface displacement zone, but that the width of this zone is largely insensitive to changes in the elastic structure (i.e., the presence of a compliant zone).

Using Paleoseismic Trenching and LiDAR Analysis to Evaluate Rupture Propagation Through Segment Boundaries of the Central Wasatch Fault Zone, Utah

NASA Astrophysics Data System (ADS)

Bennett, S. E. K.; DuRoss, C. B.; Reitman, N. G.; Devore, J. R.; Hiscock, A.; Gold, R. D.; Briggs, R. W.; Personius, S. F.

2014-12-01

Paleoseismic data near fault segment boundaries constrain the extent of past surface ruptures and the persistence of rupture termination at segment boundaries. Paleoseismic evidence for large (M≥7.0) earthquakes on the central Holocene-active fault segments of the 350-km-long Wasatch fault zone (WFZ) generally supports single-segment ruptures but also permits multi-segment rupture scenarios. The extent and frequency of ruptures that span segment boundaries remains poorly known, adding uncertainty to seismic hazard models for this populated region of Utah. To address these uncertainties we conducted four paleoseismic investigations near the Salt Lake City-Provo and Provo-Nephi segment boundaries of the WFZ. We examined an exposure of the WFZ at Maple Canyon (Woodland Hills, UT) and excavated the Flat Canyon trench (Salem, UT), 7 and 11 km, respectively, from the southern tip of the Provo segment. We document evidence for at least five earthquakes at Maple Canyon and four to seven earthquakes that post-date mid-Holocene fan deposits at Flat Canyon. These earthquake chronologies will be compared to seven earthquakes observed in previous trenches on the northern Nephi segment to assess rupture correlation across the Provo-Nephi segment boundary. To assess rupture correlation across the Salt Lake City-Provo segment boundary we excavated the Alpine trench (Alpine, UT), 1 km from the northern tip of the Provo segment, and the Corner Canyon trench (Draper, UT) 1 km from the southern tip of the Salt Lake City segment. We document evidence for six earthquakes at both sites. Ongoing geochronologic analysis (14C, optically stimulated luminescence) will constrain earthquake chronologies and help identify through-going ruptures across these segment boundaries. Analysis of new high-resolution (0.5m) airborne LiDAR along the entire WFZ will quantify latest Quaternary displacements and slip rates and document spatial and temporal slip patterns near fault segment boundaries.

Traumatic graft rupture after primary and revision anterior cruciate ligament reconstruction: retrospective analysis of incidence and risk factors in 2915 cases.

PubMed

Schlumberger, Michael; Schuster, Philipp; Schulz, Martin; Immendörfer, Micha; Mayer, Philipp; Bartholomä, Jochen; Richter, Jörg

2017-05-01

To determine incidence and risk factors for traumatic graft rupture following primary and revision anterior cruciate ligament (ACL) reconstruction. All cases of isolated ACL reconstructions (primary or revision) performed at our institution between January 2007 and December 2010 were included. From this group of 2467 primary reconstructions (32.4 ± 12.2 years) and 448 revision reconstructions (33.0 ± 10.4 years), we identified all patients who underwent revision ACL reconstruction following traumatic graft rupture in further course and all patients who underwent contralateral primary ACL reconstruction until January 2014. Age, gender, time from index procedure and graft diameter (for hamstring autografts) were analysed in terms of being a potential risk factor for graft rupture. Within a follow-up period of 5.0 ± 1.1 years (3.0-7.0), a total of 82 traumatic graft ruptures were identified, resulting in an incidence of 2.8 %. Seventy-three cases were seen following primary reconstructions (3.0 %), and nine cases following revision reconstructions (2.0 %), respectively (n.s.). Age younger than 25 years was identified as a risk factor for both groups (p = 0.001 and p = 0.008; odds ratio 6.0 and 6.4, respectively). In primary reconstruction, male patients had a higher risk of graft rupture compared with females (3.7 vs. 1.6 %; p = 0.005), and the first year after index procedure was associated with a higher risk of graft rupture compared with the following (p < 0.001). Graft diameter did not influence the risk of graft rupture. Incidence of contralateral ACL rupture was 3.1 %, which was not different to the incidence of graft rupture ipsilaterally (n.s.). No statistically significant differences were seen between graft rupture incidence of primary and revision ACL reconstructions. Young age (<25 years) and short time to the index procedure (especially within the first year) were confirmed as risk factors for graft rupture in both groups. Male gender was a risk factor for primary reconstructions. Graft diameter had no influence on graft rupture rates. No difference in incidence of graft rupture compared to ACL rupture on the contralateral side was apparent. Retrospective case series, Level IV.

Complex rupture mechanism and topography control symmetry of mass-wasting pattern, 2010 Haiti earthquake

NASA Astrophysics Data System (ADS)

Gorum, Tolga; van Westen, Cees J.; Korup, Oliver; van der Meijde, Mark; Fan, Xuanmei; van der Meer, Freek D.

2013-02-01

The 12 January 2010 Mw 7.0 Haiti earthquake occurred in a complex deformation zone at the boundary between the North American and Caribbean plates. Combined geodetic, geological and seismological data posited that surface deformation was driven by rupture on the Léogâne blind thrust fault, while part of the rupture occurred as deep lateral slip on the Enriquillo-Plantain Garden Fault (EPGF). The earthquake triggered > 4490 landslides, mainly shallow, disrupted rock falls, debris-soil falls and slides, and a few lateral spreads, over an area of ~ 2150 km2. The regional distribution of these slope failures defies those of most similar earthquake-triggered landslide episodes reported previously. Most of the coseismic landslides did not proliferate in the hanging wall of the main rupture, but clustered instead at the junction of the blind Léogâne and EPGF ruptures, where topographic relief and hillslope steepness are above average. Also, low-relief areas subjected to high coseismic uplift were prone to lesser hanging wall slope instability than previous studies would suggest. We argue that a combined effect of complex rupture dynamics and topography primarily control this previously rarely documented landslide pattern. Compared to recent thrust fault-earthquakes of similar magnitudes elsewhere, we conclude that lower static stress drop, mean fault displacement, and blind ruptures of the 2010 Haiti earthquake resulted in fewer, smaller, and more symmetrically distributed landslides than previous studies would suggest. Our findings caution against overly relying on across-the-board models of slope stability response to seismic ground shaking.

Heterogeneity of direct aftershock productivity of the main shock rupture

NASA Astrophysics Data System (ADS)

Guo, Yicun; Zhuang, Jiancang; Hirata, Naoshi; Zhou, Shiyong

2017-07-01

The epidemic type aftershock sequence (ETAS) model is widely used to describe and analyze the clustering behavior of seismicity. Instead of regarding large earthquakes as point sources, the finite-source ETAS model treats them as ruptures that extend in space. Each earthquake rupture consists of many patches, and each patch triggers its own aftershocks isotropically. We design an iterative algorithm to invert the unobserved fault geometry based on the stochastic reconstruction method. This model is applied to analyze the Japan Meteorological Agency (JMA) catalog during 1964-2014. We take six great earthquakes with magnitudes >7.5 after 1980 as finite sources and reconstruct the aftershock productivity patterns on each rupture surface. Comparing results from the point-source ETAS model, we find the following: (1) the finite-source model improves the data fitting; (2) direct aftershock productivity is heterogeneous on the rupture plane; (3) the triggering abilities of M5.4+ events are enhanced; (4) the background rate is higher in the off-fault region and lower in the on-fault region for the Tohoku earthquake, while high probabilities of direct aftershocks distribute all over the source region in the modified model; (5) the triggering abilities of five main shocks become 2-6 times higher after taking the rupture geometries into consideration; and (6) the trends of the cumulative background rate are similar in both models, indicating the same levels of detection ability for seismicity anomalies. Moreover, correlations between aftershock productivity and slip distributions imply that aftershocks within rupture faults are adjustments to coseismic stress changes due to slip heterogeneity.

Afterslip behavior following the M6.0, 2014 South Napa earthquake with implications for afterslip forecasting on other seismogenic faults

USGS Publications Warehouse

Lienkaemper, James J.; DeLong, Stephen B.; Domrose, Carolyn J; Rosa, Carla M.

2016-01-01

The M6.0, 24 Aug. 2014 South Napa, California, earthquake exhibited unusually large slip for a California strike-slip event of its size with a maximum coseismic surface slip of 40-50 cm in the north section of the 15 km-long rupture. Although only minor (<10 cm) surface slip occurred coseismically in the southern 9-km section of the rupture, there was considerable postseismic slip, so that the maximum total slip one year after the event approached 40-50 cm, about equal to the coseismic maximum in the north. We measured the accumulation of postseismic surface slip on four, ~100-m-long alignment arrays for one year following the event. Because prolonged afterslip can delay reconstruction of fault-damaged buildings and infrastructure, we analyzed its gradual decay to estimate when significant afterslip would likely end. This forecasting of Napa afterslip suggests how we might approach the scientific and engineering challenges of afterslip from a much larger M~7 earthquake anticipated on the nearby, urban Hayward Fault. However, we expect its afterslip to last much longer than one year.The M6.0, 24 Aug. 2014 South Napa, California, earthquake exhibited unusually large slip for a California strike-slip event of its size with a maximum coseismic surface slip of 40-50 cm in the north section of the 15 km-long rupture. Although only minor (<10 cm) surface slip occurred coseismically in the southern 9-km section of the rupture, there was considerable postseismic slip, so that the maximum total slip one year after the event approached 40-50 cm, about equal to the coseismic maximum in the north. We measured the accumulation of postseismic surface slip on four, ~100-m-long alignment arrays for one year following the event. Because prolonged afterslip can delay reconstruction of fault-damaged buildings and infrastructure, we analyzed its gradual decay to estimate when significant afterslip would likely end. This forecasting of Napa afterslip suggests how we might approach the scientific and engineering challenges of afterslip from a much larger M~7 earthquake anticipated on the nearby, urban Hayward Fault. However, we expect its afterslip to last much longer than one year.

Influence of Fault Surface Heterogeneity on Apparent Frictional Strength, Slip Mode and Rupture Mode: Insights from Meter-Scale Rock Friction Experiments

NASA Astrophysics Data System (ADS)

Xu, S.; Fukuyama, E.; Yamashita, F.; Mizoguchi, K.; Takizawa, S.; Kawakata, H.

2016-12-01

Influence of fault zone heterogeneity on the behavior of fault motion has been studied in many aspects, such as strain partitioning, heat generation, slip mode, rupture mode, and effective friction law. However, a multi-scale investigation of fault behavior due to heterogeneity was difficult in nature, because of the limited access to natural fault zones at the seismogenic depth and the lack of in situ high-resolution observations. To overcome these difficulties, we study the behavior of a meter-scale synthetic fault made of Indian metagabbro during laboratory direct shear experiments, utilizing high-density arrays of strain gauges mounted close to the fault. We focus on two target experiments that are loaded under the same normal stress of 6.7 MPa and loading rate of 0.01 mm/s, but with different initial surface conditions. To change the surface condition, we applied a fast loading experiment under a rate of 1 mm/s between the two target experiments. It turned out the fast loading activated many foreshocks before the mainshock and caused a roaming of the mainshock nucleation site. These features were closely related to the re-distribution of the real contact area and surface wear, which together reflected a more heterogeneous state of the surface condition. During the first target experiment before the fast loading, the synthetic fault moved in a classic stick-slip fashion and the typical rupture mode was subshear within the range of the fault length. However, during the second target experiment, the synthetic fault inherited the heterogeneous features generated from the previous fast loading, showing a macroscopic creep-like behavior that actually consisted of many small stick-slip events. The apparent frictional strength increased while the recurrence interval and the stress drop decreased, compared to the levels seen in the first target experiment. The rupture mode became more complicated; supershear phases sometimes emerged but may only exist transiently. Their occurrence or termination showed a strong correlation with the local stress field characterized by short-range coherence. These observations highlight the role of surface heterogeneity in influencing fault motion, both macroscopically and locally, and have important implications for understanding the behavior of natural faults.

Surface rupture and slip variation induced by the 2010 El Mayor-Cucapah earthquake, Baja California, quantified using COSI-Corr analysis on pre- and post-earthquake LiDAR acquisitions

NASA Astrophysics Data System (ADS)

Leprince, S.; Hudnut, K. W.; Akciz, S. O.; Hinojosa-Corona, A.; Fletcher, J. M.

2011-12-01

One-hundred and three years after the publication of the Lawson report on the Great 1906 earthquake, accurate documentation of surface deformation along the entire length of an earthquake is still challenging. Analysis of pre- and post-earthquake topographic data provides an opportunity to deliver the full 3D displacement field of the ground's surface. However, direct differencing of a pre- and post-earthquake digital topography model (DEM) generally leads to biased estimation of the vertical component of the deformation. Indeed, if the earthquake also produced significant horizontal motion, or if the pre- and post-earthquake DEM acquisitions exhibit non-negligible horizontal mis-registration, then the vertical offset measured by direct differencing will be biased by the local topography gradient. To overcome this limitation, we use the COSI-Corr sub-pixel correlation algorithm to estimate the relative horizontal offset between the pre- and post- 2010 El Mayor - Cucapah earthquake high resolution LiDAR acquisitions. Compensating for the horizontal offset between the two LiDAR acquisitions allows us to estimate unbiased measurements of the vertical component of the surface fault rupture induced by the El Mayor-Cucapah earthquake. We will also show the limitations of the available data set, such as aircraft jitter artifacts, which impaired accurate measurements of the horizontal component of the surface deformation. This analysis shows an unprecedented view of the complete vertical slip component of the rupture induced by the Mw 7.2 2010 El Mayor-Cucapah earthquake, sampled at every 5 m, over a length of about 100 km, and with a vertical accuracy of a few centimeters. Using sampling bins as narrow as 150 m and 1.5 km long, variations in the vertical component of an oblique slip earthquake are presented, with breaks along multiple fault-strands showing opposite dip directions and diffuse boundaries. With the availability of high precision pre- and post-earthquake data, COSI-Corr has the ability to accurately document the variability of 3D surface slip along strike of an earthquake rupture. Such data can be used to investigate the causes of this variability, and improve our understanding of its influence on the pattern of ground shaking.

Investigations into the mechanism of material removal and surface modification at atomic scale on stainless steel using molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Ranjan, Prabhat; Balasubramaniam, R.; Jain, V. K.

2018-06-01

A molecular dynamics simulation (MDS) has been carried out to investigate the material removal phenomenon of chemo-mechanical magnetorheological finishing (CMMRF) process. To understand the role of chemical assisted mechanical abrasion in CMMRF process, material removal phenomenon is subdivided into three different stages. In the first stage, new atomic bonds viz. Fe-O-Si is created on the surface of the workpiece (stainless steel). The second stage deals with the rupture of parent bonds like Fe-Fe on the workpiece. In the final stage, removal of material from the surface in the form of dislodged debris (cluster of atoms) takes place. Effects of process parameters like abrasive particles, depth of penetration and initial surface condition on finishing force, potential energy (towards secondary phenomenon such as chemical instability of the finished surface) and material removal at atomic scale have been investigated. It was observed that the type of abrasive particle is one of the important parameters to produce atomically smooth surface. Experiments were also conducted as per the MDS to generate defect-free and sub-nanometre-level finished surface (Ra value better than 0.2 nm). The experimental results reasonably agree well with the simulation results.

Electronic structure of strongly reduced (1 ‾ 1 1) surface of monoclinic HfO2

NASA Astrophysics Data System (ADS)

Cheng, YingXing; Zhu, Linggang; Ying, Yile; Zhou, Jian; Sun, Zhimei

2018-07-01

Material surface is playing an increasingly important role in electronic devices as their size down to nanoscale. Here, by first-principles calculations we studied the surface oxygen-vacancies (Vos) induced electronic-structure variation of HfO2 , in order to explore its potential applications in surface-controlled electronic devices. Firstly, it is found that single Vo tends to segregate onto the surface and attracts each other as they form pairs, making the formation of vacancies-contained functional surface possible. Then extensive Vo-chains whose formation/rupture can represent the high/low conductivity state are constructed. The electronic states induced by the Vos remain localized in the band-gap region for most of the Vo-chains studied here. A transition to a metallic conductance is found in metastable Vo-chain with formation energy increased by 0.25 eV per Vo. Moreover, we highlight the significance of the Hubbard U correction for density functional theory when studying the electronic-structure based conductance in the oxides. By comprehensive calculations, we find a conductivity-stability dilemma of the Vo-chains, providing guideline for understanding and designing the electronic devices based on HfO2 surface.

[Spontaneous rupture of the spleen in infectious mononucleosis: case report and review of the literature].

PubMed

Kuzman, Ilija; Kirac, Petar; Kuzman, Tomislav; Puljiz, Ivan; Bilić, Vide

2003-01-01

Spontaneous splenic rupture is a rare but potentially fatal complication of infectious mononucleosis. Abdominal pain is uncommon in infectious mononucleosis, and splenic rupture should be strongly considered whenever abdominal pain occurs. The onset of pain may be insidious or abrupt. The pain is usually in the left upper quadrant. To indicate that infectious mononucleosis is not always the innocent kissing disease, but could be complicated with splenic rupture as a life-threathenig condition. Our first case is described and a short literature review is provided. We report on the case of a 27-year-old man with infectious mononucleosis who had spontaneous splenic rupture that was successfully managed by splenectomy. On admission, he was febrile (38.5 degrees C) with hepatosplenomegaly, and had a blood pressure of 100/70 mm Hg. Six hours later, the patient complained of increasing abdominal pain. Abdominal ultrasound and computed tomography showed a 16.5 cm heterogeneous splenomegaly with subcapsular hematoma as well as free ascites. Laparotomy confirmed spontaneous rupture of the splenic capsule with active abdominal bleeding. Splenectomy was performed with a good clinical response. Examination of the spleen revealed a ruptured capsule with a subcapsular hematoma. Infectious mononucleosis is the most common infectious disease to result in spontaneous spleen rupture. The prognosis is favorable when diagnosis is made on time and correct treatment is started immediately. Although splenectomy was advocated as definitive therapy in the past, numerous recent reports have documented good outcomes with non-operative management. Based on the literature review, an approach to the management of a spontaneously ruptured spleen secondary to infectious mononucleosis is suggested. Non-operative management can be successful in hemodynamically stable patients, i.e. in patients with subcapsular hematoma without overt rupture of the capsule to avoid complications of splenectomy (e.g. post-splenectomy sepsis). We report on a 27-year-old man with infectious mononucleosis who had spontaneous splenic rupture that was successfully managed by splenectomy.

Progressive failure during the 1596 Keicho earthquakes on the Median Tectonic Line active fault zone, southwest Japan

NASA Astrophysics Data System (ADS)

Ikeda, M.; Toda, S.; Nishizaka, N.; Onishi, K.; Suzuki, S.

2015-12-01

Rupture patterns of a long fault system are controlled by spatial heterogeneity of fault strength and stress associated with geometrical characteristics and stress perturbation history. Mechanical process for sequential ruptures and multiple simultaneous ruptures, one of the characteristics of a long fault such as the North Anatolian fault, governs the size and frequency of large earthquakes. Here we introduce one of the cases in southwest Japan and explore what controls rupture initiation, sequential ruptures and fault branching on a long fault system. The Median Tectonic Line active fault zone　(hereinafter MTL) is the longest and most active fault in Japan. Based on historical accounts, a series of M ≥ 7 earthquakes occurred on at least a 300-km-long portion of the MTL in 1596. On September 1, the first event occurred on the Kawakami fault segment, in Central Shikoku, and the subsequent events occurred further west. Then on September 5, another rupture initiated from the Central to East Shikoku and then propagated toward the Rokko-Awaji fault zone to Kobe, a northern branch of the MTL, instead of the eastern main extent of the MTL. Another rupture eventually extended to near Kyoto. To reproduce this progressive failure, we applied two numerical models: one is a coulomb stress transfer; the other is a slip-tendency analysis under the tectonic stress. We found that Coulomb stress imparted from historical ruptures have triggered the subsequent ruptures nearby. However, stress transfer does not explain beginning of the sequence and rupture directivities. Instead, calculated slip-tendency values show highly variable along the MTL: high and low seismic potential in West and East Shikoku. The initiation point of the 1596 progressive failure locates near the boundary in the slip-tendency values. Furthermore, the slip-tendency on the Rokko-Awaji fault zone is far higher than that of the MTL in Wakayama, which may explain the rupture directivity toward Kobe-Kyoto.

Product surface hardening in non-self-sustained glow discharge plasma before synthesis of superhard coatings

NASA Astrophysics Data System (ADS)

Krasnov, P. S.; Metel, A. S.; Nay, H. A.

2017-05-01

Before the synthesis of superhard coating, the product surface is hardened by means of plasma nitriding, which prevents the surface deformations and the coating brittle rupture. The product heating by ions accelerated from plasma by applied to the product bias voltage leads to overheating and blunting of the product sharp edges. To prevent the blunting, it is proposed to heat the products with a broad beam of fast nitrogen molecules. The beam injection into a working vacuum chamber results in filling of the chamber with quite homogeneous plasma suitable for nitriding. Immersion in the plasma of the electrode and heightening of its potential up to 50-100 V initiate a non-self-sustained glow discharge between the electrode and the chamber. It enhances the plasma density by an order of magnitude and reduces its spatial nonuniformity down to 5-10%. When a cutting tool is isolated from the chamber, it is bombarded by plasma ions with an energy corresponding to its floating potential, which is lower than the sputtering threshold. Hence, the sharp edges are sputtered only by fast nitrogen molecules with the same rate as other parts of the tool surface. This leads to sharpening of the cutting tools instead of blunting.

Tsunami potential assessment based on rupture zones, focal mechanisms and repeat times of strong earthquakes in the major Atlantic-Mediterranean seismic fracture zone

NASA Astrophysics Data System (ADS)

Agalos, Apostolos; Papadopoulos, Gerassimos A.; Kijko, Andrzej; Papageorgiou, Antonia; Smit, Ansie; Triantafyllou, Ioanna

2016-04-01

In the major Atlantic-Mediterranean seismic fracture zone, extended from Azores islands in the west to the easternmost Mediterranean Sea in the east, including the Marmara and Black Seas, a number of 22 tsunamigenic zones have been determined from historical and instrumental tsunami documentation. Although some tsunamis were produced by volcanic activity or landslides, the majority of them was generated by strong earthquakes. Since the generation of seismic tsunamis depends on several factors, like the earthquake size, focal depth and focal mechanism, the study of such parameters is of particular importance for the assessment of the potential for the generation of future tsunamis. However, one may not rule out the possibility for tsunami generation in areas outside of the 22 zones determined so far. For the Atlantic-Mediterranean seismic fracture zone we have compiled a catalogue of strong, potentially tsunamigenic (focal depth less than 100 km) historical earthquakes from various data bases and other sources. The lateral areas of rupture zones of these earthquakes were determined. Rupture zone is the area where the strain after the earthquake has dropped substantially with respect the strain before the earthquake. Aftershock areas were assumed to determine areas of rupture zones for instrumental earthquakes. For historical earthquakes macroseismic criteria were used such as spots of higher-degree seismic intensity and of important ground failures. For the period of instrumental seismicity, focal mechanism solutions from CMT, EMMA and other data bases were selected for strong earthquakes. From the geographical distribution of seismic rupture zones and the corresponding focal mechanisms in the entire Atlantic-Mediterranean seismic fracture zone we determined potentially tsunamigenic zones regardless they are known to have produced seismic tsunamis in the past or not. An attempt has been made to calculate in each one of such zones the repeat times of strong earthquakes from earthquake catalogue data sets.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozluk, M.J.; Vijay, D.K.

Postulated catastrophic rupture of high-energy piping systems is the fundamental criterion used for the safety design basis of both light and heavy water nuclear generating stations. Historically, the criterion has been applied by assuming a nonmechanistic instantaneous double-ended guillotine rupture of the largest diameter pipes inside of containment. Nonmechanistic, meaning that the assumption of an instantaneous guillotine rupture has not been based on stresses in the pipe, failure mechanisms, toughness of the piping material, nor the dynamics of the ruptured pipe ends as they separate. This postulated instantaneous double-ended guillotine rupture of a pipe was a convenient simplifying assumption thatmore » resulted in a conservative accident scenario. This conservative accident scenario has now become entrenched as the design basis accident for: containment design, shutdown system design, emergency fuel cooling systems design, and to establish environmental qualification temperature and pressure conditions. The requirement to address dynamic effects associated with the postulated pipe rupture subsequently evolved. The dynamic effects include: potential missiles, pipe whipping, blowdown jets, and thermal-hydraulic transients. Recent advances in fracture mechanics research have demonstrated that certain pipes under specific conditions cannot crack in ways that result in an instantaneous guillotine rupture. Canadian utilities are now using mechanistic fracture mechanics and leak-before-break assessments on a case-by-case basis, in limited applications, to support licensing cases which seek exemption from the need to consider the various dynamic effects associated with postulated instantaneous catastrophic rupture of high-energy piping systems inside and outside of containment.« less

Head-on collision of drops: A numerical investigation

NASA Technical Reports Server (NTRS)

Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.

1993-01-01

The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

Liquid salt environment stress-rupture testing

DOEpatents

Ren, Weiju; Holcomb, David E.; Muralidharan, Govindarajan; Wilson, Dane F.

2016-03-22

Disclosed herein are systems, devices and methods for stress-rupture testing selected materials within a high-temperature liquid salt environment. Exemplary testing systems include a load train for holding a test specimen within a heated inert gas vessel. A thermal break included in the load train can thermally insulate a load cell positioned along the load train within the inert gas vessel. The test specimen can include a cylindrical gage portion having an internal void filled with a molten salt during stress-rupture testing. The gage portion can have an inner surface area to volume ratio of greater than 20 to maximize the corrosive effect of the molten salt on the specimen material during testing. Also disclosed are methods of making a salt ingot for placement within the test specimen.

Spontaneous Rupture of Umbilical Hernia in Pregnancy: A Case Report

PubMed Central

Ahmed, Adamu; Stephen, Garba; Ukwenya, Yahaya

2011-01-01

A 28 year old woman presented with a spontaneous rupture of an umbilical hernia in her seventh month of pregnancy. She had four previous unsupervised normal deliveries. There was no history of trauma or application of herbal medicine on the hernia. The hernia sac ruptured at the inferior surface where it was attached to the ulcerated and damaged overlying skin. There was a gangrenous eviscerated small bowel. The patient was resuscitated and the gangrenous small bowel was resected and end to end anastomosis done. The hernia sac was excised and the 12 cm defect repaired. Six weeks later, she had spontaneous vaginal delivery of a live baby. We advocate that large umbilical hernias should be routinely repaired when seen in women of child bearing age. PMID:22043438

Paleoseismic Trenching on 1939 Erzincan and 1942 Niksar-Erbaa Earthquake Surface Ruptures, the North Anatolian Fault (Turkey)

NASA Astrophysics Data System (ADS)

Akyuz, H. S.; Karabacak, V.; Zabci, C.; Sancar, T.; Altunel, E.; Gursoy, H.; Tatar, O.

2009-04-01

Two devastating earthquakes occurred between Erzincan (39.75N, 39.49E) and Erbaa, Tokat (40.70N, 36.58E) just three years one after another in 1939 and 1942. While 1939 Erzincan earthquake (M=7.8) ruptured nearly 360 km, 1942 Erbaa-Niksar earthquake (M=7.1) has a length of 50 km surface rupture. Totally, more than 35000 citizens lost their lives after these events. Although Turkey has one of the richest historical earthquake records, there is no clear evidence of the spatial distribution of paleoevents within these two earthquake segments of the North Anatolian Fault. 17 August 1668 Anatolian earthquake is one of the known previous earthquakes that may have occurred on the same segments with a probable rupture length of more than 400 km. It is still under debate in different catalogues, if it was ruptured in multiple events or a single one. We achieved paleoseismic trench studies to have a better understanding on the recurrence of large earthquakes on these two faults in the framework of T.C. DPT. Project no. 2006K120220. We excavated a total of 8 trenches in 7 different sites. While three of them are along the 1942 Erbaa-Niksar Earthquake rupture, others are located on the 1939 Erzincan one. Alanici and Direkli trenches were excavated on the 1942 rupture. Direkli trench site is located at the west of Niksar, Tokat (40.62N, 36.85E) on the fluvial terrace deposits of the Kelkit River. Only one paleoevent could be determined from the structural relationships of the trench wall stratigraphy. By radiocarbon dating of charcoal sample from above the event horizon indicates that this earthquake should have occurred before 480-412 BC. The second trench, Alanici, on the same segment was located between Erbaa and Niksar (40.65N, 36.78E) at the western boundary of a sag-pond. While signs of two (possible three) earthquakes were identified on the trench wall, the prior event to 1942 Earthquake is dated to be before 5th century AD. We interpreted this to have possibility of missing intermediate events or dating of reworked samples. To resolve this problem, another trenching (Gunese trench; 40.67N, 36.68E) was done close to western end of 1942 Earthquake rupture. Three events were logged on the trench wall, which was exposed by excavating a linear depression. Penultimate event horizon contains many of small ceramic pieces, which may mark a large hazard. Umurca trench excavated on the 1939 Erzincan earthquake surface rupture. From three (possible 4) paleoevents of Umurca Trench (40.32N, 37.57E), penultimate event, UMURCA-2, was determined to be after 1625- 1644 AD) and UMURCA-3 to be after 1409-1455 AD with radiocarbon dating. In addition to that, some preliminary dating results of Resadiye-2 trench (40.38N, 37.34E) give a panultimate event, RES-2, to be before 1423-1522 AD and a prior one RES-3 to be after 894-1045 AD. Radiocarbon dating of samples from the project's last year trenches and some more from the previous ones are still underway. There will be a clearer picture in terms of understanding recurrence character of the North Anatolian Fault along these segments after having of all dating results.

The 1995 November 22, Mw 7.2 Gulf of Elat earthquake cycle revisited

NASA Astrophysics Data System (ADS)

Baer, Gidon; Funning, Gareth J.; Shamir, Gadi; Wright, Tim J.

2008-12-01

The 1995 November 22, Mw = 7.2 Nuweiba earthquake occurred along one of the left-stepping segments of the Dead Sea Transform (DST) in the Gulf of Elat (Aqaba). It was the largest earthquake along the DST in at least 160 yr. The main shock was preceded by earthquake swarms north and south of its NE-striking rupture since the early 1980s, and was followed by about 6 months of intense aftershock activity, concentrated mainly northwest and southeast of the main rupture. In this study we re-analyse ERS-1 and ERS-2 InSAR data for the period spanning the main shock and 5 post-seismic years. Because the entire rupture was under the Gulf water, surface observations related to the earthquake are limited to distances greater than 5 km away from the rupture zone. Coseismic interferograms were produced for the earthquake +1 week, +4 months and +6 months. Non-linear inversions were carried out for fault geometry and linear inversions were made for slip distribution using an ascending-descending 2-frame data set. The moment calculated from our best-fitting model is in agreement with the seismological moment, but trade-offs exist among several fault parameters. The present model upgrades previous InSAR models of the Nuweiba earthquake, and differs from recent teleseismic waveform inversion results mainly in terms of slip magnitude and distribution. The moment released by post-seismic deformation in the period of 6 months to 2 yr after the Nuweiba earthquake is about 15 per cent of the coseismic moment release. Our models suggest that this deformation can be represented by slip along the lower part of the coseismic rupture. Localised deformation along the Gulf shores NW of the main rupture in the first 6 months after the earthquake is correlated with surface displacements along active Gulf-parallel normal faults and possibly with shallow M > 3.9, D < 6 km aftershocks. The geodetic moment calculated by modelling this deformation is more than an order of magnitude larger than expected for a single M ~ 4 aftershock, but could be a result of a sequence of aftershocks and/or aseismic slip. The major aftershocks and the slip along Gulf-parallel normal faulting NW of the main rupture are associated with positive Coulomb stress changes induced by the main event.

Using a pseudo-dynamic source inversion approach to improve earthquake source imaging

NASA Astrophysics Data System (ADS)

Zhang, Y.; Song, S. G.; Dalguer, L. A.; Clinton, J. F.

2014-12-01

Imaging a high-resolution spatio-temporal slip distribution of an earthquake rupture is a core research goal in seismology. In general we expect to obtain a higher quality source image by improving the observational input data (e.g. using more higher quality near-source stations). However, recent studies show that increasing the surface station density alone does not significantly improve source inversion results (Custodio et al. 2005; Zhang et al. 2014). We introduce correlation structures between the kinematic source parameters: slip, rupture velocity, and peak slip velocity (Song et al. 2009; Song and Dalguer 2013) in the non-linear source inversion. The correlation structures are physical constraints derived from rupture dynamics that effectively regularize the model space and may improve source imaging. We name this approach pseudo-dynamic source inversion. We investigate the effectiveness of this pseudo-dynamic source inversion method by inverting low frequency velocity waveforms from a synthetic dynamic rupture model of a buried vertical strike-slip event (Mw 6.5) in a homogeneous half space. In the inversion, we use a genetic algorithm in a Bayesian framework (Moneli et al. 2008), and a dynamically consistent regularized Yoffe function (Tinti, et al. 2005) was used for a single-window slip velocity function. We search for local rupture velocity directly in the inversion, and calculate the rupture time using a ray-tracing technique. We implement both auto- and cross-correlation of slip, rupture velocity, and peak slip velocity in the prior distribution. Our results suggest that kinematic source model estimates capture the major features of the target dynamic model. The estimated rupture velocity closely matches the target distribution from the dynamic rupture model, and the derived rupture time is smoother than the one we searched directly. By implementing both auto- and cross-correlation of kinematic source parameters, in comparison to traditional smoothing constraints, we are in effect regularizing the model space in a more physics-based manner without loosing resolution of the source image. Further investigation is needed to tune the related parameters of pseudo-dynamic source inversion and relative weighting between the prior and the likelihood function in the Bayesian inversion.

Electric Motor Thermal Management Research: Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennion, Kevin S.

Past work in the area of active convective cooling provided data on the average convective heat transfer coefficients of circular orifice automatic transmission fluid (ATF) jets impinging on stationary targets intended to represent the wire bundle surface of the motor end-winding. Work during FY16 focused on the impact of alternative jet geometries that could lead to improved cooling over a larger surface of the motor winding. Results show that the planar jet heat transfer coefficients over a small (12.7-mm-diameter) target surface are not too much lower than for the circular orifice jet in which all of the ATF from themore » jet impinges on the target surface. The planar jet has the potential to achieve higher heat transfer over a larger area of the motor end winding. A new test apparatus was constructed to measure the spatial dependence of the heat transfer relative to the jet nozzle over a larger area representative of a motor end-winding. The tested planar flow geometry has the potential to provide more uniform cooling over the full end-winding surface versus the conventional jet configuration. The data will be used by motor designers to develop thermal management strategies to improve motor power density. Work on passive thermal design in collaboration with Oak Ridge National Laboratory to measure the thermal conductivity of wire bundle samples representative of end-winding and slot-winding materials was completed. Multiple measurement techniques were compared to determine which was most suitable for measuring composite wire bundle samples. NREL used a steady-state thermal resistance technique to measure the direction-dependent thermal conductivity. The work supported new interactions with industry to test new materials and reduce passive-stack thermal resistance in motors, leading to motors with increased power density. NREL collaborated with Ames Laboratory in the area of material characterization. The work focused on measuring the transverse rupture strength of new magnet materials developed at Ames. The impact of the improved transverse rupture strength is a mechanically stronger magnet that is easier for manufacturers to implement into motor designs. The thermal conductivity of the new magnet materials was also measured in comparison to two commercially available AlNiCo magnet materials. The impact of the thermal conductivity of the magnet material will need to be analyzed in the context of a motor application.« less

Paleoseismic history and slip rate along the Sapanca-Akyazı segment of the 1999 İzmit earthquake rupture (Mw = 7.4) of the North Anatolian Fault (Turkey)

NASA Astrophysics Data System (ADS)

Dikbaş, Aynur; Akyüz, H. Serdar; Meghraoui, Mustapha; Ferry, Matthieu; Altunel, Erhan; Zabcı, Cengiz; Langridge, Robert; Yalçıner, Cahit Çağlar

2018-07-01

The Sapanca-Akyazı segment (SAS) is located on western part of the North Anatolian Fault (NAF) of Turkey. It was ruptured together with four other segments during the 17th August 1999 İzmit earthquake (Mw = 7.4) which caused 145-km-long surface rupture in the east Marmara region. We conducted geomorphological investigations and 2D-3D paleoseismic trenching at 3 different sites near the Sakarya River along the SAS to obtain new data for the timing of past earthquakes and slip rate of this section of the NAF. Detailed investigations using Ground Penetrating Radar on the western bank of the Sakarya River reveal 18.5 ± 0.5 m of right-lateral cumulative offset of an alluvial terrace dated as 850 ± 11 years BP using Optically Stimulated Luminescence. The analysis of trench data from the three different sites of the SAS indicates the occurrence of four surface rupturing past earthquakes including the 1999 İzmit earthquake. According to the radiocarbon dating, these paleo-earthquakes can be correlated with the 1719 CE, 1567 CE, and 1037 CE historical earthquakes and suggest an average recurrence period between 273 and 322 years. The total dextral offset, the age of trench units and the terrace deposits together suggest a 22 ± 3 mm/yr slip rate for this portion of the NAF.

[Assessment, delivery and peripartum care in the case of a uterine rupture during labor of a woman with a previous C-section].

PubMed

Parrilla-Fernández, Alberto; Manrique-Tejedor, Javier; Figuerol-Calderó, M Inmaculada; García-Romero, Verónica

Uterine rupture is a rare but severe complication in obstetrics. A previous C-section is the most important risk factor. Its incidence during labor in women with a previous C-section is of approximately 0.3-0.47%, being potentially severe. We present the case of a pregnant women with a previous C-section who suffered uterine rupture during labor. The rapid assessment and action of the midwife and obstetric team was essential to obtain a successful obstetric outcome, avoiding maternal and fetal mortality; and nursing care given to the mother and the newborn after birth contributed to achieving a normal postpartum. It is necessary to have specific knowledge about this condition that, despite rare, can present insidiously with a potential risk for the mother and the fetus. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Interactive Mechanisms of Sliding-Surface Bearings.

DTIC Science & Technology

1983-08-01

lower, upper) bearing surface V Three-dimensional gradient operator ix Two-dimensional surface gradient operator ( ),. Pertaining to the bearing surface...thermal gradients . The tilt-pad feature required the pad inclination to be determined by the condition of moment equilibrium about the pivot point. This...into the computation of pressure and shear in a fluid film. Incipience Point of Film Rupture On page 93 of Appendix A, pressure gradient and pressure of

On- and off-fault deformation associated with the September 2013 Mw7.7 Balochistan earthquake: implications for geologic slip rate measurements

USGS Publications Warehouse

Gold, Ryan D.; Reitman, Nadine G.; Briggs, Richard; Barnhart, William; Hayes, Gavin; Wilson, Earl M.

2015-01-01

The 24 September 2013 Mw7.7 Balochistan, Pakistan earthquake ruptured a ~ 200 km-long stretch of the Hoshab fault in southern Pakistan and produced the second-largest lateral surface displacement observed for a continental strike-slip earthquake. We remotely measured surface deformation associated with this event using high-resolution (0.5 m) pre- and post-event satellite optical imagery. We document left lateral, near-field, on-fault offsets (10 m from fault) using 309 laterally offset piercing points, such as streams, terrace risers, and roads. Peak near-field displacement is 13.6 + 2.5/− 3.4 m. We characterize off-fault deformation by measuring medium- (< 350 m from fault) and far-field (> 350 m from fault) displacement using manual (259 measurements) and automated image cross-correlation methods, respectively. Off-fault peak lateral displacement values are ~ 15 m and exceed on-fault displacement magnitudes for ~ 85% of the rupture length. Our observations suggest that for this rupture, coseismic surface displacement typically increases with distance away from the surface trace of the fault; however, nearly 100% of total surface displacement occurs within a few hundred meters of the primary fault trace. Furthermore, off-fault displacement accounts for, on average, 28% of the total displacement but exhibits a highly heterogeneous along-strike pattern. The best agreement between near-field and far-field displacements generally corresponds to the narrowest fault zone widths. Our analysis demonstrates significant and heterogeneous mismatches between on- and off-fault coseismic deformation, and we conclude that this phenomenon should be considered in hazard models based on geologically determined on-fault slip rates.

Seismogeodesy of the 2014 Mw6.1 Napa earthquake, California: Rapid response and modeling of fast rupture on a dipping strike-slip fault

NASA Astrophysics Data System (ADS)

Melgar, Diego; Geng, Jianghui; Crowell, Brendan W.; Haase, Jennifer S.; Bock, Yehuda; Hammond, William C.; Allen, Richard M.

2015-07-01

Real-time high-rate geodetic data have been shown to be useful for rapid earthquake response systems during medium to large events. The 2014 Mw6.1 Napa, California earthquake is important because it provides an opportunity to study an event at the lower threshold of what can be detected with GPS. We show the results of GPS-only earthquake source products such as peak ground displacement magnitude scaling, centroid moment tensor (CMT) solution, and static slip inversion. We also highlight the retrospective real-time combination of GPS and strong motion data to produce seismogeodetic waveforms that have higher precision and longer period information than GPS-only or seismic-only measurements of ground motion. We show their utility for rapid kinematic slip inversion and conclude that it would have been possible, with current real-time infrastructure, to determine the basic features of the earthquake source. We supplement the analysis with strong motion data collected close to the source to obtain an improved postevent image of the source process. The model reveals unilateral fast propagation of slip to the north of the hypocenter with a delayed onset of shallow slip. The source model suggests that the multiple strands of observed surface rupture are controlled by the shallow soft sediments of Napa Valley and do not necessarily represent the intersection of the main faulting surface and the free surface. We conclude that the main dislocation plane is westward dipping and should intersect the surface to the east, either where the easternmost strand of surface rupture is observed or at the location where the West Napa fault has been mapped in the past.

Seismic constraints and coulomb stress changes of a blind thrust fault system, 1: Coalinga and Kettleman hills, California

USGS Publications Warehouse

Lin, Jian; Stein, Ross S.

2006-01-01

This report reviews the seismicity and surface ruptures associated with the 1982-1985 earthquake sequence in the Coalinga region in California, and the role of Coulomb stress in triggering the mainshock sequence and aftershocks. The 1982-1985 New Idria, Coalinga, and Kettleman Hills earthquakes struck on a series of west-dipping, en echelon blind thrust faults. Each earthquake was accompanied by uplift of a Quaternary anticline atop the fault, and each was accompanied by a vigorous aftershock sequence. Aftershocks were widely dispersed, and are seen above and below the thrust fault, as well as along the up-dip and down-dip projection of the main thrust fault. For the Coalinga and Kettleman Hills earthquakes, high-angle reverse faults in the core of the anticlines are evident in seismic reflection profiles, and many of these faults are associated with small aftershocks. The shallowest aftershocks extended to within 3-4 km of the ground surface. There is no compelling evidence for aftershocks associated with flexural slip faulting. No secondary surface rupture was found on any of the anticlines. In contrast, the 1983 Nu?ez rupture struck on a high-angle reverse fault 10 km west of the Coalinga epicenter, and over a 40-80-day period, up to 1 m of oblique surface slip occurred. The slip on this Holocene fault likely extended from the ground surface to a depth of 8-10 km. We argue that both the Nu?ez and Kettleman earthquakes were triggered by stresses imparted by the Coalinga mainshock, which was the largest of the four events in the sequence.

On- and off-fault deformation associated with the September 2013 Mw 7.7 Balochistan earthquake: Implications for geologic slip rate measurements

NASA Astrophysics Data System (ADS)

Gold, Ryan D.; Reitman, Nadine G.; Briggs, Richard W.; Barnhart, William D.; Hayes, Gavin P.; Wilson, Earl

2015-10-01

The 24 September 2013 Mw7.7 Balochistan, Pakistan earthquake ruptured a ~ 200 km-long stretch of the Hoshab fault in southern Pakistan and produced the second-largest lateral surface displacement observed for a continental strike-slip earthquake. We remotely measured surface deformation associated with this event using high-resolution (0.5 m) pre- and post-event satellite optical imagery. We document left lateral, near-field, on-fault offsets (10 m from fault) using 309 laterally offset piercing points, such as streams, terrace risers, and roads. Peak near-field displacement is 13.6 + 2.5/- 3.4 m. We characterize off-fault deformation by measuring medium- (< 350 m from fault) and far-field (> 350 m from fault) displacement using manual (259 measurements) and automated image cross-correlation methods, respectively. Off-fault peak lateral displacement values are ~ 15 m and exceed on-fault displacement magnitudes for ~ 85% of the rupture length. Our observations suggest that for this rupture, coseismic surface displacement typically increases with distance away from the surface trace of the fault; however, nearly 100% of total surface displacement occurs within a few hundred meters of the primary fault trace. Furthermore, off-fault displacement accounts for, on average, 28% of the total displacement but exhibits a highly heterogeneous along-strike pattern. The best agreement between near-field and far-field displacements generally corresponds to the narrowest fault zone widths. Our analysis demonstrates significant and heterogeneous mismatches between on- and off-fault coseismic deformation, and we conclude that this phenomenon should be considered in hazard models based on geologically determined on-fault slip rates.

Microvessel rupture induced by high-intensity therapeutic ultrasound-a study of parameter sensitivity in a simple in vivo model.

PubMed

Kim, Yeonho; Nabili, Marjan; Acharya, Priyanka; Lopez, Asis; Myers, Matthew R

2017-01-01

Safety analyses of transcranial therapeutic ultrasound procedures require knowledge of the dependence of the rupture probability and rupture time upon sonication parameters. As previous vessel-rupture studies have concentrated on a specific set of exposure conditions, there is a need for more comprehensive parametric studies. Probability of rupture and rupture times were measured by exposing the large blood vessel of a live earthworm to high-intensity focused ultrasound pulse trains of various characteristics. Pressures generated by the ultrasound transducers were estimated through numerical solutions to the KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation. Three ultrasound frequencies (1.1, 2.5, and 3.3 MHz) were considered, as were three pulse repetition frequencies (1, 3, and 10 Hz), and two duty factors (0.0001, 0.001). The pressures produced ranged from 4 to 18 MPa. Exposures of up to 10 min in duration were employed. Trials were repeated an average of 11 times. No trends as a function of pulse repetition rate were identifiable, for either probability of rupture or rupture time. Rupture time was found to be a strong function of duty factor at the lower pressures; at 1.1 MHz the rupture time was an order of magnitude lower for the 0.001 duty factor than the 0.0001. At moderate pressures, the difference between the duty factors was less, and there was essentially no difference between duty factors at the highest pressure. Probability of rupture was not found to be a strong function of duty factor. Rupture thresholds were about 4 MPa for the 1.1 MHz frequency, 7 MPa at 3.3 MHz, and 11 MPa for the 2.5 MHz, though the pressure value at 2.5 MHz frequency will likely be reduced when steep-angle corrections are accounted for in the KZK model used to estimate pressures. Mechanical index provided a better collapse of the data (less separation of the curves pertaining to the different frequencies) than peak negative pressure, for both probability of rupture and rupture time. The results provide a database with which investigations in more complex animal models can be compared, potentially establishing trends by which bioeffects in human vessels can be estimated.

Source modeling of the 2015 Mw 7.8 Nepal (Gorkha) earthquake sequence: Implications for geodynamics and earthquake hazards

NASA Astrophysics Data System (ADS)

McNamara, D. E.; Yeck, W. L.; Barnhart, W. D.; Schulte-Pelkum, V.; Bergman, E.; Adhikari, L. B.; Dixit, A.; Hough, S. E.; Benz, H. M.; Earle, P. S.

2017-09-01

The Gorkha earthquake on April 25th, 2015 was a long anticipated, low-angle thrust-faulting event on the shallow décollement between the India and Eurasia plates. We present a detailed multiple-event hypocenter relocation analysis of the Mw 7.8 Gorkha Nepal earthquake sequence, constrained by local seismic stations, and a geodetic rupture model based on InSAR and GPS data. We integrate these observations to place the Gorkha earthquake sequence into a seismotectonic context and evaluate potential earthquake hazard. Major results from this study include (1) a comprehensive catalog of calibrated hypocenters for the Gorkha earthquake sequence; (2) the Gorkha earthquake ruptured a 150 × 60 km patch of the Main Himalayan Thrust (MHT), the décollement defining the plate boundary at depth, over an area surrounding but predominantly north of the capital city of Kathmandu (3) the distribution of aftershock seismicity surrounds the mainshock maximum slip patch; (4) aftershocks occur at or below the mainshock rupture plane with depths generally increasing to the north beneath the higher Himalaya, possibly outlining a 10-15 km thick subduction channel between the overriding Eurasian and subducting Indian plates; (5) the largest Mw 7.3 aftershock and the highest concentration of aftershocks occurred to the southeast the mainshock rupture, on a segment of the MHT décollement that was positively stressed towards failure; (6) the near surface portion of the MHT south of Kathmandu shows no aftershocks or slip during the mainshock. Results from this study characterize the details of the Gorkha earthquake sequence and provide constraints on where earthquake hazard remains high, and thus where future, damaging earthquakes may occur in this densely populated region. Up-dip segments of the MHT should be considered to be high hazard for future damaging earthquakes.

Source modeling of the 2015 Mw 7.8 Nepal (Gorkha) earthquake sequence: Implications for geodynamics and earthquake hazards

USGS Publications Warehouse

McNamara, Daniel E.; Yeck, William; Barnhart, William D.; Schulte-Pelkum, V.; Bergman, E.; Adhikari, L. B.; Dixit, Amod; Hough, S.E.; Benz, Harley M.; Earle, Paul

2017-01-01

The Gorkha earthquake on April 25th, 2015 was a long anticipated, low-angle thrust-faulting event on the shallow décollement between the India and Eurasia plates. We present a detailed multiple-event hypocenter relocation analysis of the Mw 7.8 Gorkha Nepal earthquake sequence, constrained by local seismic stations, and a geodetic rupture model based on InSAR and GPS data. We integrate these observations to place the Gorkha earthquake sequence into a seismotectonic context and evaluate potential earthquake hazard.Major results from this study include (1) a comprehensive catalog of calibrated hypocenters for the Gorkha earthquake sequence; (2) the Gorkha earthquake ruptured a ~ 150 × 60 km patch of the Main Himalayan Thrust (MHT), the décollement defining the plate boundary at depth, over an area surrounding but predominantly north of the capital city of Kathmandu (3) the distribution of aftershock seismicity surrounds the mainshock maximum slip patch; (4) aftershocks occur at or below the mainshock rupture plane with depths generally increasing to the north beneath the higher Himalaya, possibly outlining a 10–15 km thick subduction channel between the overriding Eurasian and subducting Indian plates; (5) the largest Mw 7.3 aftershock and the highest concentration of aftershocks occurred to the southeast the mainshock rupture, on a segment of the MHT décollement that was positively stressed towards failure; (6) the near surface portion of the MHT south of Kathmandu shows no aftershocks or slip during the mainshock. Results from this study characterize the details of the Gorkha earthquake sequence and provide constraints on where earthquake hazard remains high, and thus where future, damaging earthquakes may occur in this densely populated region. Up-dip segments of the MHT should be considered to be high hazard for future damaging earthquakes.

3-D kinematics analysis of surface ruptures on an active creeping fault at Chihshang, Eastern Taiwan

NASA Astrophysics Data System (ADS)

Lee, J.; Angelier, J.; Chen, H.; Chu, H.; Hu, J.

2003-12-01

The Chihshang fault is one of the most active segments of the Longitudinal Valley Fault, the plate suture between the converging Philippine and Eurasian plates. A destructive earthquake of M 7.1 with substantial surface scarps resulted from rupturing of the Chihshang fault in 1951. From that on, no big earthquake greater than M 5.5 occurred in this area. Instead, the Chihshang fault reveals a creeping behavior at a rapid rate of about 20 mm/yr at least during the past 20 years. The surface breaks of the creeping Chihshang fault can be observed at the several places. A typical feature is reverse-fault-like fractures on the retaining wall. We deployed small geodetic networks across the fault zone at five sites. Each network comprises of 5 to 15 benchmarks. Trilateration measurements including angles and distances as well as leveling among the benchmarks have been carried out on an annual basis or twice a year since 1998. Compared to previous other measurements which have shown the first order creep rate for the entire fault zone, the present geodetic data provides the detailed information of the surface movements across the fault zone which usually composed of more than one fault strands and folds structures. According to our data from the local geodetic networks, we are able to reconstruct the 3-D kinematics of surface deformation across the Chihshang fault zone. Multiple fault strands are common along the Chihshang fault. Oblique shortening occurred at all sites and was characterized by a combination of thrusts, backthrust and surface warps. Strike-slip motion can also be distinguished on some fault strands. It is worth to note that the cultural feature, such as concrete basement of strong resistance, sometimes acted as deflection of surface ruptures. It should be taken into consideration for mitigation against seismic hazards.

Stress-Rupture of New Tyranno Si-C-O-Zr Fiber Reinforced Minicomposites

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.

1999-01-01

Minicomposites consisting of two varieties of Zr containing SiC-based fibers from Ube (Tyranno) with BN interphases and CVI SiC matrices were studied. The two fiber-types were the ZMI and ZE fiber-types that contain approximately 8 and 2% oxygen, respectively. The minicomposites were precracked and tested under constant load testing at temperatures ranging from 700 to 1200 C. The data were then compared to the rupture behavior of Hi- Nicalon (TM) fiber reinforced minicomposites tested under identical conditions. It was found that the Ube fiber-types had stress rupture life equivalent to Hi- Nicalon (TM) over the entire temperature range. A potential benefit of the ZMI fiber-type is that it offers rupture properties almost as good as Hi-Nicalon (TM) at the cost of ceramic grade Nicalon (TM).

Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength

USGS Publications Warehouse

Beeler, N.M.; Tullis, T.E.

1996-01-01

Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The rise time and rupture propagation velocity depend on the choice of constitutive parameters. The second strength function is a natural log velocity-dependent form similar to constitutive laws that fit experimental rock friction data at lower velocities. Slip pulses also arise with this function. For a reasonable choice of constitutive parameters, slip pulses with this function do not propagate at speeds greater than the Raleighwave velocity. The calculated slip pulses are similar in many aspects to seismic observations of short rise time. In all cases of self-healing slip pulses, the residual stress increases with distance behind the trailing edge of the pulse so that the final stress drop is much less than the dynamic stress drop, in agreement with the model of Brune (1976) and some recent seismological observations of rupture.

Postglacial seismic activity along the Isovaara-Riikonkumpu fault complex

NASA Astrophysics Data System (ADS)

Ojala, Antti E. K.; Mattila, Jussi; Ruskeeniemi, Timo; Palmu, Jukka-Pekka; Lindberg, Antero; Hänninen, Pekka; Sutinen, Raimo

2017-10-01

Analysis of airborne LiDAR-based digital elevation models (DEMs), trenching of Quaternary deposits, and diamond drilling through faulted bedrock was conducted to characterize the geological structure and full slip profiles of the Isovaara-Riikonkumpu postglacial fault (PGF) complex in northern Finland. The PGF systems are recognized from LiDAR DEMs as a complex of surface ruptures striking SW-NE, cutting through late-Weichselian till, and associated with several postglacial landslides within 10 km. Evidence from the terrain rupture characteristics, the deformed and folded structure of late-Weichselian till, and the 14C age of 11,300 cal BP from buried organic matter underneath the Sotka landslide indicates a postglacial origin of the Riikonkumpu fault (PGF). The fracture frequency and lithology of drill cores and fault geometry in the trench log indicate that the Riikonkumpu PGF dips to WNW with a dip angle of 40-45° at the Riikonkumpu site and close to 60° at the Riikonvaara site. A fault length of 19 km and the mean and maximum cumulative vertical displacement of 1.3 m and 4.1 m, respectively, of the Riikonkumpu PGF system indicate that the fault potentially hosted an earthquake with a moment magnitude MW ≈ 6.7-7.3 assuming that slip was accumulated in one seismic event. Our interpretation further suggests that the Riikonkumpu PGF system is linked to the Isovaara PGF system and that, together, they form a larger Isovaara-Riikonkumpu fault complex. Relationships between the 38-km-long rupture of the Isovaara-Riikonkumpu complex and the fault offset parameters, with cumulative displacement of 1.5 and 8.3 m, respectively, indicate that the earthquake(s) contributing to the PGF complex potentially had a moment magnitude of MW ≈ 6.9-7.5. In order to adequately sample the uncertainty space, the moment magnitude was also estimated for each major segment within the Isovaara-Riikonkumpu PGF complex. These estimates vary roughly between MW ≈ 5-8 for the individual segments.

Biomechanical Indices for Rupture Risk Estimation in Abdominal Aortic Aneurysms.

PubMed

Leemans, Eva L; Willems, Tineke P; van der Laan, Maarten J; Slump, Cornelis H; Zeebregts, Clark J

2017-04-01

To review the use of biomechanical indices for the estimation of abdominal aortic aneurysm (AAA) rupture risk, emphasizing their potential use in a clinical setting. A search of the PubMed, Embase, Scopus, and Compendex databases was made up to June 2015 to identify articles involving biomechanical analysis of AAA rupture risk. Outcome variables [aneurysm diameter, peak wall stress (PWS), peak wall shear stress (PWSS), wall strain, peak wall rupture index (PWRI), and wall stiffness] were compared for asymptomatic intact AAAs vs symptomatic or ruptured AAAs. For quantitative analysis of the pooled data, a random effects model was used to calculate the standard mean differences (SMDs) with the 95% confidence interval (CI) for the biomechanical indices. The initial database searches yielded 1894 independent articles of which 19 were included in the analysis. The PWS was significantly higher in the symptomatic/ruptured group, with a SMD of 1.11 (95% CI 0.93 to 1.26, p<0.001). Likewise, the PWRI was significantly higher in the ruptured or symptomatic group, with a SMD of 1.15 (95% CI 0.30 to 2.01, p=0.008). After adjustment for the aneurysm diameter, the PWS remained higher in the ruptured or symptomatic group, with a SMD of 0.85 (95% CI 0.46 to 1.23, p<0.001). Less is known of the wall shear stress and wall strain indices, as too few studies were available for analysis. Biomechanical indices are a promising tool in the assessment of AAA rupture risk as they incorporate several factors, including geometry, tissue properties, and patient-specific risk factors. However, clinical implementation of biomechanical AAA assessment remains a challenge owing to a lack of standardization.

A penalty-based nodal discontinuous Galerkin method for spontaneous rupture dynamics

NASA Astrophysics Data System (ADS)

Ye, R.; De Hoop, M. V.; Kumar, K.

2017-12-01

Numerical simulation of the dynamic rupture processes with slip is critical to understand the earthquake source process and the generation of ground motions. However, it can be challenging due to the nonlinear friction laws interacting with seismicity, coupled with the discontinuous boundary conditions across the rupture plane. In practice, the inhomogeneities in topography, fault geometry, elastic parameters and permiability add extra complexity. We develop a nodal discontinuous Galerkin method to simulate seismic wave phenomenon with slipping boundary conditions, including the fluid-solid boundaries and ruptures. By introducing a novel penalty flux, we avoid solving Riemann problems on interfaces, which makes our method capable for general anisotropic and poro-elastic materials. Based on unstructured tetrahedral meshes in 3D, the code can capture various geometries in geological model, and use polynomial expansion to achieve high-order accuracy. We consider the rate and state friction law, in the spontaneous rupture dynamics, as part of a nonlinear transmitting boundary condition, which is weakly enforced across the fault surface as numerical flux. An iterative coupling scheme is developed based on implicit time stepping, containing a constrained optimization process that accounts for the nonlinear part. To validate the method, we proof the convergence of the coupled system with error estimates. We test our algorithm on a well-established numerical example (TPV102) of the SCEC/USGS Spontaneous Rupture Code Verification Project, and benchmark with the simulation of PyLith and SPECFEM3D with agreeable results.

Breast augmentation and reconstructive surgery: MR imaging of implant rupture and malignancy.

PubMed

Herborn, Christoph U; Marincek, Borut; Erfmann, Daniel; Meuli-Simmen, Claudia; Wedler, Volker; Bode-Lesniewska, Beate; Kubik-Huch, Rahel A

2002-09-01

The purpose of this study was to assess the diagnostic accuracy of MRI in detecting prosthesis integrity and malignancy after breast augmentation and reconstruction. Forty-one implants in 25 patients were analyzed by MRI before surgical removal. Imaging results were compared with ex vivo findings. Magnetic resonance imaging of the breast was performed on a 1.5-T system using a dedicated surface breast coil. Axial and sagittal T2-weighted fast spin-echo as well as dynamic contrast-enhanced T1-weighted gradient-recalled-echo sequences were acquired. The linguine sign indicating collapse of the silicone shell or siliconomas indicating free silicone proved implant rupture, whereas early focal contrast enhancement of a lesion was suspicious for malignancy. The sensitivity for detection of implant rupture was 86.7% with a specificity of 88.5%. The positive and negative predictive values were 81.3 and 92.0%, respectively. The linguine sign as a predictor of intracapsular implant rupture had a sensitivity of 80% with a specificity of 96.2%. Magnetic resonance imaging revealed two lesions with suspicious contrast enhancement (one carcinoma, one extra-abdominal fibromatosis). Magnetic resonance imaging is a reliable and reproducible technique for diagnosing both implant rupture and malignant lesions in women after breast augmentation and reconstruction.

Causal mechanisms of seismo-EM phenomena during the 1965-1967 Matsushiro earthquake swarm.

PubMed

Enomoto, Yuji; Yamabe, Tsuneaki; Okumura, Nobuo

2017-03-21

The 1965-1967 Matsushiro earthquake swarm in central Japan exhibited two unique characteristics. The first was a hydro-mechanical crust rupture resulting from degassing, volume expansion of CO 2 /water, and a crack opening within the critically stressed crust under a strike-slip stress. The other was, despite the lower total seismic energy, the occurrence of complexed seismo-electromagnetic (seismo-EM) phenomena of the geomagnetic intensity increase, unusual earthquake lights (EQLs) and atmospheric electric field (AEF) variations. Although the basic rupture process of this swarm of earthquakes is reasonably understood in terms of hydro-mechanical crust rupture, the associated seismo-EM processes remain largely unexplained. Here, we describe a series of seismo-EM mechanisms involved in the hydro-mechanical rupture process, as observed by coupling the electric interaction of rock rupture with CO 2 gas and the dielectric-barrier discharge of the modelled fields in laboratory experiments. We found that CO 2 gases passing through the newly created fracture surface of the rock were electrified to generate pressure-impressed current/electric dipoles, which could induce a magnetic field following Biot-Savart's law, decrease the atmospheric electric field and generate dielectric-barrier discharge lightning affected by the coupling effect between the seismic and meteorological activities.

Causal mechanisms of seismo-EM phenomena during the 1965–1967 Matsushiro earthquake swarm

PubMed Central

Enomoto, Yuji; Yamabe, Tsuneaki; Okumura, Nobuo

2017-01-01

The 1965–1967 Matsushiro earthquake swarm in central Japan exhibited two unique characteristics. The first was a hydro-mechanical crust rupture resulting from degassing, volume expansion of CO2/water, and a crack opening within the critically stressed crust under a strike-slip stress. The other was, despite the lower total seismic energy, the occurrence of complexed seismo-electromagnetic (seismo-EM) phenomena of the geomagnetic intensity increase, unusual earthquake lights (EQLs) and atmospheric electric field (AEF) variations. Although the basic rupture process of this swarm of earthquakes is reasonably understood in terms of hydro-mechanical crust rupture, the associated seismo-EM processes remain largely unexplained. Here, we describe a series of seismo-EM mechanisms involved in the hydro-mechanical rupture process, as observed by coupling the electric interaction of rock rupture with CO2 gas and the dielectric-barrier discharge of the modelled fields in laboratory experiments. We found that CO2 gases passing through the newly created fracture surface of the rock were electrified to generate pressure-impressed current/electric dipoles, which could induce a magnetic field following Biot-Savart’s law, decrease the atmospheric electric field and generate dielectric-barrier discharge lightning affected by the coupling effect between the seismic and meteorological activities. PMID:28322263

Laboratory experiment of seismic cycles using compliant viscoelastic materials

NASA Astrophysics Data System (ADS)

Yamaguchi, T.

2016-12-01

It is well known that surface asperities at fault interfaces play an essential role in stick-slip friction. There have been many laboratory experiments conducted using rocks and some analogue materials to understand the effects of asperities and the underlying mechanisms. Among such materials, soft polymer gels have great advantages of slowing down propagating rupture front speed as well as shear wave speed: it facilitates observation of the dynamic rupture behavior. However, most experiments were done with bimaterial interfaces (combination of soft and hard materials) and there are few experiments with an identical (gel on gel) setup. Furthermore, there have been also few studies mentioning the link between local asperity contact and macroscopic dynamic rupture behavior. In this talk, we report our experimental studies on stick-slip friction between gels having controlled artificial asperities. We show that, depending on number density and configuration randomness of the asperities, the rupture behavior greatly changes: when the asperities are located periodically with optimum number densities, fast rupture propagation occurs, while slow and heterogeneous slip behavior is observed for samples having randomly located asperities. We discuss the importance of low frequency (large wavelength) excitation of the normal displacement contributing to weakening the fault interface. We also discuss the observed regular to slow slip transition with a simple model.

Causal mechanisms of seismo-EM phenomena during the 1965-1967 Matsushiro earthquake swarm

NASA Astrophysics Data System (ADS)

Enomoto, Yuji; Yamabe, Tsuneaki; Okumura, Nobuo

2017-03-01

The 1965-1967 Matsushiro earthquake swarm in central Japan exhibited two unique characteristics. The first was a hydro-mechanical crust rupture resulting from degassing, volume expansion of CO2/water, and a crack opening within the critically stressed crust under a strike-slip stress. The other was, despite the lower total seismic energy, the occurrence of complexed seismo-electromagnetic (seismo-EM) phenomena of the geomagnetic intensity increase, unusual earthquake lights (EQLs) and atmospheric electric field (AEF) variations. Although the basic rupture process of this swarm of earthquakes is reasonably understood in terms of hydro-mechanical crust rupture, the associated seismo-EM processes remain largely unexplained. Here, we describe a series of seismo-EM mechanisms involved in the hydro-mechanical rupture process, as observed by coupling the electric interaction of rock rupture with CO2 gas and the dielectric-barrier discharge of the modelled fields in laboratory experiments. We found that CO2 gases passing through the newly created fracture surface of the rock were electrified to generate pressure-impressed current/electric dipoles, which could induce a magnetic field following Biot-Savart’s law, decrease the atmospheric electric field and generate dielectric-barrier discharge lightning affected by the coupling effect between the seismic and meteorological activities.

Seismic potential of weak, near-surface faults revealed at plate tectonic slip rates

PubMed Central

Ikari, Matt J.; Kopf, Achim J.

2017-01-01

The near-surface areas of major faults commonly contain weak, phyllosilicate minerals, which, based on laboratory friction measurements, are assumed to creep stably. However, it is now known that shallow faults can experience tens of meters of earthquake slip and also host slow and transient slip events. Laboratory experiments are generally performed at least two orders of magnitude faster than plate tectonic speeds, which are the natural driving conditions for major faults; the absence of experimental data for natural driving rates represents a critical knowledge gap. We use laboratory friction experiments on natural fault zone samples at driving rates of centimeters per year to demonstrate that there is abundant evidence of unstable slip behavior that was not previously predicted. Specifically, weak clay-rich fault samples generate slow slip events (SSEs) and have frictional properties favorable for earthquake rupture. Our work explains growing field observations of shallow SSE and surface-breaking earthquake slip, and predicts that such phenomena should be more widely expected. PMID:29202027

Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential

NASA Astrophysics Data System (ADS)

Li, Hua; Wood, Ross J.; Endres, Frank; Atkin, Rob

2014-07-01

Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces.

Role of slope stability in cumulative impact assessment of hydropower development: North Cascades, Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, R.R.; Staub, W.P.

1993-08-01

Two environmental assessments considered the potential cumulative environmental impacts resulting from the development of eight proposed hydropower projects in the Nooksack River Basin and 11 proposed projects in the Skagit River Basin, North Cascades, Washington, respectively. While not identified as a target resource, slope stability and the alteration of sediment supply to creeks and river mainstems significantly affect other resources. The slope stability assessment emphasized the potential for cumulative impacts under disturbed conditions (e.g., road construction and timber harvesting) and a landslide-induced pipeline rupture scenario. In the case of small-scale slides, the sluicing action of ruptured pipeline water on themore » fresh landslide scarp was found to be capable of eroding significantly more material than the original landslide. For large-scale landslides, sluiced material was found to be a small increment of the original landslide. These results predicted that hypothetical accidental pipeline rupture by small-scale landslides may result in potential cumulative impacts for 12 of the 19 projects with pending license applications in both river basins. 5 refs., 2 tabs.« less

Induction of cell death by the lysosomotropic detergent MSDH.

PubMed

Li, W; Yuan, X; Nordgren, G; Dalen, H; Dubowchik, G M; Firestone, R A; Brunk, U T

2000-03-17

Controlled lysosomal rupture was initiated in lysosome-rich, macrophage-like cells by the synthetic lysosomotropic detergent, O-methyl-serine dodecylamide hydrochloride (MSDH). When MSDH was applied at low concentrations, resulting in partial lysosomal rupture, activation of pro-caspase-3-like proteases and apoptosis followed after some hours. Early during apoptosis, but clearly secondary to lysosomal destabilization, the mitochondrial transmembrane potential declined. At high concentrations, MSDH caused extensive lysosomal rupture and necrosis. It is suggested that lysosomal proteases, if released to the cytosol, may cause apoptosis directly by pro-caspase activation and/or indirectly by mitochondrial attack with ensuing discharge of pro-apoptotic factors.

Case report: spontaneous rupture of spleen in patient with Plasmodium ovale malaria.

PubMed

Lemmerer, Raphael; Unger, Manuel; Voßen, Matthias; Forstner, Christina; Jalili, Ahmad; Starzengruber, Peter; Werzowa, Johannes; Ramharter, Michael; Winkler, Stefan; Thalhammer, Florian

2016-01-01

Malaria may lead to spontaneous splenic rupture as a rare but potentially lethal complication. Most frequently, this has been reported in patients infected with Plasmodium falciparum and Plasmodium vivax, while other parasitic agents are less likely to be the cause.We report a 29-year-old British Caucasian, who after returning from a business trip in Democratic Republic Congo was diagnosed with tertian malaria caused by Plasmodium ovale.During his in-patient stay, the patient suffered a splenic rupture requiring immediate surgical intervention and splenectomy. Following this surgical intervention, there was an uneventful recovery, and the patient was discharged in a good general condition.

It's Our Fault: better defining earthquake risk in Wellington, New Zealand

NASA Astrophysics Data System (ADS)

Van Dissen, R.; Brackley, H. L.; Francois-Holden, C.

2012-12-01

The Wellington region, home of New Zealand's capital city, is cut by a number of major right-lateral strike slip faults, and is underlain by the currently locked west-dipping subduction interface between the down going Pacific Plate, and the over-riding Australian Plate. In its short historic period (ca. 160 years), the region has been impacted by large earthquakes on the strike-slip faults, but has yet to bear the brunt of a subduction interface rupture directly beneath the capital city. It's Our Fault is a comprehensive study of Wellington's earthquake risk. Its objective is to position the capital city of New Zealand to become more resilient through an encompassing study of the likelihood of large earthquakes, and the effects and impacts of these earthquakes on humans and the built environment. It's Our Fault is jointly funded by New Zealand's Earthquake Commission, Accident Compensation Corporation, Wellington City Council, Wellington Region Emergency Management Group, Greater Wellington Regional Council, and Natural Hazards Research Platform. The programme has been running for six years, and key results to date include better definition and constraints on: 1) location, size, timing, and likelihood of large earthquakes on the active faults closest to Wellington; 2) earthquake size and ground shaking characterization of a representative suite of subduction interface rupture scenarios under Wellington; 3) stress interactions between these faults; 4) geological, geotechnical, and geophysical parameterisation of the near-surface sediments and basin geometry in Wellington City and the Hutt Valley; and 5) characterisation of earthquake ground shaking behaviour in these two urban areas in terms of subsoil classes specified in the NZ Structural Design Standard. The above investigations are already supporting measures aimed at risk reduction, and collectively they will facilitate identification of additional actions that will have the greatest benefit towards further increasing the region's resilience to earthquakes. We present latest results on ground motion simulations for large plate interface earthquakes under Wellington in terms of response spectra and acceleration time histories. We derive realistic broadband accelerograms based on a stochastic modelling technique. First we characterise the potential interface rupture area based on previous geodetically-derived estimates interface of slip deficit. Then, we entertain a suitable range of source parameters, including various rupture areas, moment magnitudes, stress drops, slip distributions and rupture propagation directions. The resulting rupture scenarios all produce long duration shaking, and peak ground accelerations that, typically, range between 0.2-0.7 g in Wellington city. Many of these scenarios also produce long period motions that are currently not captured by the current NZ design spectra.

Pulling monatomic gold wires with single molecules: an Ab initio simulation.

PubMed

Krüger, Daniel; Fuchs, Harald; Rousseau, Roger; Marx, Dominik; Parrinello, Michele

2002-10-28

Car-Parrinello molecular dynamics simulations demonstrate that pulling a single thiolate molecule anchored on a stepped gold surface does not preferentially break the sulfur-gold chemical bond. Instead, it is found that this process leads to the formation of a monoatomic gold nanowire, followed by breaking a gold-gold bond with a rupture force of about 1.2 nN. The simulations also indicate that previous single-molecule thiolate-gold and gold-gold rupture experiments both probe the same phenomenon, namely, the breaking of a gold-gold bond within a gold nanowire.

Terahertz NDE of Stressed Composite Overwrapped Pressure Vessels - Initial Testing

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Seebo, Jeffrey P.; Anatasi, Robert F.

2009-01-01

Terahertz radiation nondestructive evaluation was applied to a set of Kevlar composite overwrapped pressure vessel bottles that had undergone a series of thermal and pressure tests to simulate stress rupture effects. The bottles in these nondestructive evaluation tests were bottles that had not ruptured but had survived various times at the elevated load and temperature levels. Some of the bottles showed evidence of minor composite failures. The terahertz radiation did detect visible surface flaws, but did not detect any internal chemical or material degradation of the thin overwraps.

Refining the Magnitude of the Shallow Slip Deficit

NASA Astrophysics Data System (ADS)

Xu, X.; Tong, X.; Sandwell, D. T.; Milliner, C. W. D.

2014-12-01

Geodetic inversions for slip versus depth for several major (Mw > 7) strike-slip earthquakes (e.g. 1992 Landers, 1999 Hector Mine, 2010 El_Mayor-Cucapah) show a 10% to 40% reduction in slip near surface (depth < 2 km) compared to the slip at deeper depths (5 to 8 km). This has been called the shallow slip deficit (SSD). The large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes. One potential explanation for the SSD is that the previous geodetic inversions used incomplete data that do not go close to fault so the shallow portions of the slip models were poorly resolved and generally underestimated. In this study we improve the geodetic inversion, especially at shallow depth by: 1) refining the InSAR processing with non-boxcar phase filtering, model-dependent range corrections, more complete phase unwrapping by SNAPHU using a correlation mask and allowing a phase discontinuity along the rupture; 2) including near-fault offset data from optical imagery and SAR azimuth offsets; 3) using more detailed fault geometry; 4) and using additional campaign GPS data. With these improved observations, the slip inversion has significantly increased resolution at shallow depth. For the Landers rupture the SSD is reduced from 45% to 16%. Similarly for the Hector Mine rupture the SSD is reduced from 15% to 5%. We are assembling all the relevant co-seismic data for the El Major-Cucapah earthquake and will report the inversion result with its SSD at the meeting.

Strain release along ocean transform faults

NASA Astrophysics Data System (ADS)

Stewart, L. M.

A global study of the nature of seismic rupture along oceanic transform faults (TFs) is presented, and many aspects of fault behavior and Mid-Ocean Ridge processes are discussed. A classification of TF earthquakes is developed based on their relative excitation of short period body waves to long period surface waves. Since the ways in which transform faults release their accumulated strain varies, for more than 50 earthquakes occurring on 30 TFs since 1963 form the database for a comparison of rupture processes. The variation of TF rupture processes is not related to spreading rate or TF offset. A study of seismicity of the Eltanin Fracture Zone system shows that unlike many TFs, the Eltanin FZ realizes more than 90% of its slip aseismically. This identifies a major portion of plate boundary whose motion persists undetected by seismic instruments. The global variations in rupture patterns are discussed in terms of current models of fault behavior. The versatility of the asperity model accommodates the entire range of observed patterns. Variations in physical properties within TF contact zones (asperities) are documented in the petrology and geochemistry of rocks from ophiolite sections and TFs.

Microstructure characterization in domestically-made TP310HNbN austenitic stainless steel after creep test

NASA Astrophysics Data System (ADS)

Guo, Yan; Lin, Lin; Hou, Shufang; Wang, Bohan

Microstructure characterization of domestically-made TP310HNbN austenitic stainless steel after creep test was investigated by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results revealed that M23C6 carbides precipitated both inside grains and at the grain boundaries and NbCrN particles were located inside grains for creep-rupture samples. It was clear that sigma phase and NbC particles precipitated inside grains for the creep-rupture sample at 670 C. M23C6 carbides with lattice parameter of three times of the austenite matrix grow in a cube to cube orientation relationship with the matrix. The amount of M23C6 carbide particles obviously increased with the testing time prolonged. Deformation hardening induced an enhanced hardness nearby rupture surface for the creep-rupture samples with a short testing time. For the domestically-made TP310HNbN steel, great attention should be paid to the distribution, size and amount of sigma phase and M23C6 during service.

Comparison of nondestructive testing methods for evaluating No. 2 Southern Pine lumber: Part B, modulus of rupture

Treesearch

B.Z. Yang; R.D. Seale; R. Shmulsky; J. Dahlen; X. Wang

2017-01-01

The identification of strength-reducing characteristics that impact modulus of rupture (MOR) is a key differentiation between lumber grades. Because global design values for MOR are at the fifth percentile level and in-grade lumber can be highly variable, it is important that nondestructive evaluation technology be used to better discern the potential wood strength. In...

Abridged republication of FIGO's staging classification for cancer of the ovary, fallopian tube, and peritoneum.

PubMed

Prat, Jaime

2015-10-01

Ovarian, fallopian tube, and peritoneal cancers have a similar clinical presentation and are treated similarly, and current evidence supports staging all 3 cancers in a single system. The primary site (i.e. ovary, fallopian tube, or peritoneum) should be designated where possible. The histologic type should be recorded. Intraoperative rupture ("surgical spill") is IC1; capsule ruptured before surgery or tumor on ovarian or fallopian tube surface is IC2; and positive peritoneal cytology with or without rupture is IC3. The new staging includes a revision of stage III patients; assignment to stage IIIA1 is based on spread to the retroperitoneal lymph nodes without intraperitoneal dissemination. Extension of tumor from omentum to spleen or liver (stage IIIC) should be differentiated from isolated parenchymal metastases (stage IVB). © 2015 American Cancer Society.

Dynamic rupture simulations of the 2016 Mw7.8 Kaikōura earthquake: a cascading multi-fault event

NASA Astrophysics Data System (ADS)

Ulrich, T.; Gabriel, A. A.; Ampuero, J. P.; Xu, W.; Feng, G.

2017-12-01

The Mw7.8 Kaikōura earthquake struck the Northern part of New Zealand's South Island roughly one year ago. It ruptured multiple segments of the contractional North Canterbury fault zone and of the Marlborough fault system. Field observations combined with satellite data suggest a rupture path involving partly unmapped faults separated by large stepover distances larger than 5 km, the maximum distance usually considered by the latest seismic hazard assessment methods. This might imply distant rupture transfer mechanisms generally not considered in seismic hazard assessment. We present high-resolution 3D dynamic rupture simulations of the Kaikōura earthquake under physically self-consistent initial stress and strength conditions. Our simulations are based on recent finite-fault slip inversions that constrain fault system geometry and final slip distribution from remote sensing, surface rupture and geodetic data (Xu et al., 2017). We assume a uniform background stress field, without lateral fault stress or strength heterogeneity. We use the open-source software SeisSol (www.seissol.org) which is based on an arbitrary high-order accurate DERivative Discontinuous Galerkin method (ADER-DG). Our method can account for complex fault geometries, high resolution topography and bathymetry, 3D subsurface structure, off-fault plasticity and modern friction laws. It enables the simulation of seismic wave propagation with high-order accuracy in space and time in complex media. We show that a cascading rupture driven by dynamic triggering can break all fault segments that were involved in this earthquake without mechanically requiring an underlying thrust fault. Our prefered fault geometry connects most fault segments: it does not features stepover larger than 2 km. The best scenario matches the main macroscopic characteristics of the earthquake, including its apparently slow rupture propagation caused by zigzag cascading, the moment magnitude and the overall inferred slip distribution. We observe a high sensitivity of cascading dynamics on fault-step over distance and off-fault energy dissipation.

Joint inversion of GNSS and teleseismic data for the rupture process of the 2017 M w6.5 Jiuzhaigou, China, earthquake

NASA Astrophysics Data System (ADS)

Li, Qi; Tan, Kai; Wang, Dong Zhen; Zhao, Bin; Zhang, Rui; Li, Yu; Qi, Yu Jie

2018-02-01

The spatio-temporal slip distribution of the earthquake that occurred on 8 August 2017 in Jiuzhaigou, China, was estimated from the teleseismic body wave and near-field Global Navigation Satellite System (GNSS) data (coseismic displacements and high-rate GPS data) based on a finite fault model. Compared with the inversion results from the teleseismic body waves, the near-field GNSS data can better restrain the rupture area, the maximum slip, the source time function, and the surface rupture. The results show that the maximum slip of the earthquake approaches 1.4 m, the scalar seismic moment is 8.0 × 1018 N·m (M w ≈ 6.5), and the centroid depth is 15 km. The slip is mainly driven by the left-lateral strike-slip and it is initially inferred that the seismogenic fault occurs in the south branch of the Tazang fault or an undetectable fault, a NW-trending left-lateral strike-slip fault, and belongs to one of the tail structures at the easternmost end of the eastern Kunlun fault zone. The earthquake rupture is mainly concentrated at depths of 5-15 km, which results in the complete rupture of the seismic gap left by the previous four earthquakes with magnitudes > 6.0 in 1973 and 1976. Therefore, the possibility of a strong aftershock on the Huya fault is low. The source duration is 30 s and there are two major ruptures. The main rupture occurs in the first 10 s, 4 s after the earthquake; the second rupture peak arrives in 17 s. In addition, the Coulomb stress study shows that the epicenter of the earthquake is located in the area where the static Coulomb stress change increased because of the 12 May 2017 M w7.9 Wenchuan, China, earthquake. Therefore, the Wenchuan earthquake promoted the occurrence of the 8 August 2017 Jiuzhaigou earthquake.

Kinematic Seismic Rupture Parameters from a Doppler Analysis

NASA Astrophysics Data System (ADS)

Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.

2010-05-01

The radiation emitted from extended seismic sources, mainly when the rupture spreads in preferred directions, presents spectral deviations as a function of the observation location. This aspect, unobserved to point sources, and named as directivity, are manifested by an increase in the frequency and amplitude of seismic waves when the rupture occurs in the direction of the seismic station and a decrease in the frequency and amplitude if it occurs in the opposite direction. The model of directivity that supports the method is a Doppler analysis based on a kinematic source model of rupture and wave propagation through a structural medium with spherical symmetry [1]. A unilateral rupture can be viewed as a sequence of shocks produced along certain paths on the fault. According this model, the seismic record at any point on the Earth's surface contains a signature of the rupture process that originated the recorded waveform. Calculating the rupture direction and velocity by a general Doppler equation, - the goal of this work - using a dataset of common time-delays read from waveforms recorded at different distances around the epicenter, requires the normalization of measures to a standard value of slowness. This normalization involves a non-linear inversion that we solve numerically using an iterative least-squares approach. The evaluation of the performance of this technique was done through a set of synthetic and real applications. We present the application of the method at four real case studies, the following earthquakes: Arequipa, Peru (Mw = 8.4, June 23, 2001); Denali, AK, USA (Mw = 7.8; November 3, 2002); Zemmouri-Boumerdes, Algeria (Mw = 6.8, May 21, 2003); and Sumatra, Indonesia (Mw = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data. [1] Caldeira B., Bezzeghoud M, Borges JF, 2009; DIRDOP: a directivity approach to determining the seismic rupture velocity vector. J Seismology, DOI 10.1007/s10950-009-9183-x

Joint inversion of GNSS and teleseismic data for the rupture process of the 2017 M w6.5 Jiuzhaigou, China, earthquake

NASA Astrophysics Data System (ADS)

Li, Qi; Tan, Kai; Wang, Dong Zhen; Zhao, Bin; Zhang, Rui; Li, Yu; Qi, Yu Jie

2018-05-01

The spatio-temporal slip distribution of the earthquake that occurred on 8 August 2017 in Jiuzhaigou, China, was estimated from the teleseismic body wave and near-field Global Navigation Satellite System (GNSS) data (coseismic displacements and high-rate GPS data) based on a finite fault model. Compared with the inversion results from the teleseismic body waves, the near-field GNSS data can better restrain the rupture area, the maximum slip, the source time function, and the surface rupture. The results show that the maximum slip of the earthquake approaches 1.4 m, the scalar seismic moment is 8.0 × 1018 N·m ( M w ≈ 6.5), and the centroid depth is 15 km. The slip is mainly driven by the left-lateral strike-slip and it is initially inferred that the seismogenic fault occurs in the south branch of the Tazang fault or an undetectable fault, a NW-trending left-lateral strike-slip fault, and belongs to one of the tail structures at the easternmost end of the eastern Kunlun fault zone. The earthquake rupture is mainly concentrated at depths of 5-15 km, which results in the complete rupture of the seismic gap left by the previous four earthquakes with magnitudes > 6.0 in 1973 and 1976. Therefore, the possibility of a strong aftershock on the Huya fault is low. The source duration is 30 s and there are two major ruptures. The main rupture occurs in the first 10 s, 4 s after the earthquake; the second rupture peak arrives in 17 s. In addition, the Coulomb stress study shows that the epicenter of the earthquake is located in the area where the static Coulomb stress change increased because of the 12 May 2017 M w7.9 Wenchuan, China, earthquake. Therefore, the Wenchuan earthquake promoted the occurrence of the 8 August 2017 Jiuzhaigou earthquake.

Pulverization provides a mechanism for the nucleation of earthquakes at low stress on strong faults

USGS Publications Warehouse

Felzer, Karen R.

2014-01-01

An earthquake occurs when rock that has been deformed under stress rebounds elastically along a fault plane (Gilbert, 1884; Reid, 1911), radiating seismic waves through the surrounding earth. Rupture along the entire fault surface does not spontaneously occur at the same time, however. Rather the rupture starts in one tiny area, the rupture nucleation zone, and spreads sequentially along the fault. Like a row of dominoes, one bit of rebounding fault triggers the next. This triggering is understood to occur because of the large dynamic stresses at the tip of an active seismic rupture. The importance of these crack tip stresses is a central question in earthquake physics. The crack tip stresses are minimally important, for example, in the time predictable earthquake model (Shimazaki and Nakata, 1980), which holds that prior to rupture stresses are comparable to fault strength in many locations on the future rupture plane, with bits of variation. The stress/strength ratio is highest at some point, which is where the earthquake nucleates. This model does not require any special conditions or processes at the nucleation site; the whole fault is essentially ready for rupture at the same time. The fault tip stresses ensure that the rupture occurs as a single rapid earthquake, but the fact that fault tip stresses are high is not particularly relevant since the stress at most points does not need to be raised by much. Under this model it should technically be possible to forecast earthquakes based on the stress-renewaql concept, or estimates of when the fault as a whole will reach the critical stress level, a practice used in official hazard mapping (Field, 2008). This model also indicates that physical precursors may be present and detectable, since stresses are unusually high over a significant area before a large earthquake.

3-D Spontaneous Rupture Simulations of the 2016 Kumamoto, Japan, Earthquake

NASA Astrophysics Data System (ADS)

Urata, Yumi; Yoshida, Keisuke; Fukuyama, Eiichi

2017-04-01

We investigated the M7.3 Kumamoto, Japan, earthquake to illuminate why and how the rupture of the main shock propagated successfully by 3-D dynamic rupture simulations, assuming a complicated fault geometry estimated based on the distributions of aftershocks. The M7.3 main shock occurred along the Futagawa and Hinagu faults. A few days before, three M6-class foreshocks occurred. Their hypocenters were located along by the Hinagu and Futagawa faults and their focal mechanisms were similar to those of the main shock; therefore, an extensive stress shadow can have been generated on the fault plane of the main shock. First, we estimated the geometry of the fault planes of the three foreshocks as well as that of the main shock based on the temporal evolution of relocated aftershock hypocenters. Then, we evaluated static stress changes on the main shock fault plane due to the occurrence of the three foreshocks assuming elliptical cracks with constant stress drops on the estimated fault planes. The obtained static stress change distribution indicated that the hypocenter of the main shock is located on the region with positive Coulomb failure stress change (ΔCFS) while ΔCFS in the shallow region above the hypocenter was negative. Therefore, these foreshocks could encourage the initiation of the main shock rupture and could hinder the rupture propagating toward the shallow region. Finally, we conducted 3-D dynamic rupture simulations of the main shock using the initial stress distribution, which was the sum of the static stress changes by these foreshocks and the regional stress field. Assuming a slip-weakening law with uniform friction parameters, we conducted 3-D dynamic rupture simulations by varying the friction parameters and the values of the principal stresses. We obtained feasible parameter ranges to reproduce the rupture propagation of the main shock consistent with those revealed by seismic waveform analyses. We also demonstrated that the free surface encouraged the slip evolution of the main shock.

A Test Case for the Source Inversion Validation: The 2014 ML 5.5 Orkney, South Africa Earthquake

NASA Astrophysics Data System (ADS)

Ellsworth, W. L.; Ogasawara, H.; Boettcher, M. S.

2017-12-01

The ML5.5 earthquake of August 5, 2014 occurred on a near-vertical strike slip fault below abandoned and active gold mines near Orkney, South Africa. A dense network of surface and in-mine seismometers recorded the earthquake and its aftershock sequence. In-situ stress measurements and rock samples through the damage zone and rupture surface are anticipated to be available from the "Drilling into Seismogenic Zones of M2.0-M5.5 Earthquakes in South African gold mines" project (DSeis) that is currently progressing toward the rupture zone (Science, doi: 10.1126/science.aan6905). As of 24 July, 95% of drilled core has been recovered from a 427m-section of the 1st hole from 2.9 km depth with minimal core discing and borehole breakouts. A 2nd hole is planned to intersect the fault at greater depth. Absolute differential stress will be measured along the holes and frictional characteristics of the recovered core will be determined in the lab. Surface seismic reflection data and exploration drilling from the surface down to the mining horizon at 3km depth is also available to calibrate the velocity structure above the mining horizon and image reflective geological boundaries and major faults below the mining horizon. The remarkable quality and range of geophysical data available for the Orkney earthquake makes this event an ideal test case for the Source Inversion Validation community using actual seismic data to determine the spatial and temporal evolution of earthquake rupture. We invite anyone with an interest in kinematic modeling to develop a rupture model for the Orkney earthquake. Seismic recordings of the earthquake and information on the faulting geometry can be found in Moyer et al. (2017, doi: 10.1785/0220160218). A workshop supported by the Southern California Earthquake Center will be held in the spring of 2018 to compare kinematic models. Those interested in participating in the modeling exercise and the workshop should contact the authors for additional information.

The 2016 central Italy earthquake sequence: surface effects, fault model and triggering scenarios

NASA Astrophysics Data System (ADS)

Chatzipetros, Alexandros; Pavlides, Spyros; Papathanassiou, George; Sboras, Sotiris; Valkaniotis, Sotiris; Georgiadis, George

2017-04-01

The results of fieldwork performed during the 2016 earthquake sequence around the karstic basins of Norcia and La Piana di Castelluccio, at an altitude of 1400 m, on the Monte Vettore (altitude 2476 m) and Vettoretto, as well as the three mapped seismogenic faults, striking NNW-SSW, are presented in this paper. Surface co-seismic ruptures were observed in the Vettore and Vettoretto segment of the fault for several kilometres ( 7 km) in the August earthquakes at high altitudes, and were re-activated and expanded northwards during the October earthquakes. Coseismic ruptures and the neotectonic Mt. Vettore fault zone were modelled in detail using images acquired from specifically planned UAV (drone) flights. Ruptures, typically with displacement of up to 20 cm, were observed after the August event both in the scree and weathered mantle (elluvium), as well as the bedrock, consisting mainly of fragmented carbonate rocks with small tectonic surfaces. These fractures expanded and new ones formed during the October events, typically of displacements of up to 50 cm, although locally higher displacements of up to almost 2 m were observed. Hundreds of rock falls and landslides were mapped through satellite imagery, using pre- and post- earthquake Sentinel 2A images. Several of them were also verified in the field. Based on field mapping results and seismological information, the causative faults were modelled. The model consists of five seismogenic sources, each one associated with a strong event in the sequence. The visualisation of the seismogenic sources follows INGV's DISS standards for the Individual Seismogenic Sources (ISS) layer, while strike, dip and rake of the seismic sources are obtained from selected focal mechanisms. Based on this model, the ground deformation pattern was inferred, using Okada's dislocation solution formulae, which shows that the maximum calculated vertical displacement is 0.53 m. This is in good agreement with the statistical analysis of the observed surface rupture displacement. Stress transfer analysis was also performed in the five modelled seismogenic sources, using seismologically defined parameters. The resulting stress transfer pattern, based on the sequence of events, shows that the causative fault of each event was influenced by loading from the previous ones.

Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

USGS Publications Warehouse

Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

2010-01-01

This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

Spontaneous splenic rupture in infectious mononucleosis: case report and review of the literature.

PubMed

Rinderknecht, Andrea S; Pomerantz, Wendy J

2012-12-01

A 15-year-old previously healthy girl presented in full arrest after 1 week of flu-like symptoms, recent diagnosis of infectious mononucleosis, and 1 day of abdominal pain. There was no history of trauma. Focused assessment with sonography for trauma examination showed free fluid in the abdomen. The patient died despite aggressive resuscitative management and emergency laparotomy with splenectomy, which showed grade V splenic laceration. Infectious mononucleosis is a common viral illness of adolescence. Spontaneous splenic rupture is a rare but potentially fatal complication. Anticipatory guidance about the importance of seeking medical care if abdominal pain develops during infectious mononucleosis is crucial to early diagnosis and intervention in the case of rupture. We discuss the current literature surrounding the outpatient follow-up of splenomegaly associated with infectious mononucleosis, as well as current practice and treatment options when rupture occurs.

Analysis of rainfall-induced slope instability using a field of local factor of safety

USGS Publications Warehouse

Lu, Ning; Şener-Kaya, Başak; Wayllace, Alexandra; Godt, Jonathan W.

2012-01-01

Slope-stability analyses are mostly conducted by identifying or assuming a potential failure surface and assessing the factor of safety (FS) of that surface. This approach of assigning a single FS to a potentially unstable slope provides little insight on where the failure initiates or the ultimate geometry and location of a landslide rupture surface. We describe a method to quantify a scalar field of FS based on the concept of the Coulomb stress and the shift in the state of stress toward failure that results from rainfall infiltration. The FS at each point within a hillslope is called the local factor of safety (LFS) and is defined as the ratio of the Coulomb stress at the current state of stress to the Coulomb stress of the potential failure state under the Mohr-Coulomb criterion. Comparative assessment with limit-equilibrium and hybrid finite element limit-equilibrium methods show that the proposed LFS is consistent with these approaches and yields additional insight into the geometry and location of the potential failure surface and how instability may initiate and evolve with changes in pore water conditions. Quantitative assessments applying the new LFS field method to slopes under infiltration conditions demonstrate that the LFS has the potential to overcome several major limitations in the classical FS methodologies such as the shape of the failure surface and the inherent underestimation of slope instability. Comparison with infinite-slope methods, including a recent extension to variably saturated conditions, shows further enhancement in assessing shallow landslide occurrence using the LFS methodology. Although we use only a linear elastic solution for the state of stress with no post-failure analysis that require more sophisticated elastoplastic or other theories, the LFS provides a new means to quantify the potential instability zones in hillslopes under variably saturated conditions using stress-field based methods.

A molecular scale perspective: Monte Carlo simulation for rupturing of ultra thin polymer film melts

NASA Astrophysics Data System (ADS)

Singh, Satya Pal

2017-04-01

Monte Carlo simulation has been performed to study the rupturing process of thin polymer film under strong confinement. The change in mean square displacement; pair correlation function; density distribution; average bond length and microscopic viscosity are sampled by varying the molecular interaction parameters such as the strength and the equilibrium positions of the bonding, non-bonding potentials and the sizes of the beads. The variation in mean square angular displacement χθ = [ < Δθ2 > - < Δθ>2 ] fits very well to a function of type y (t) = A + B *e-t/τ. This may help to study the viscous properties of the films and its dependence on different parameters. The ultra thin film annealed at high temperature gets ruptured and holes are created in the film mimicking spinodal dewetting. The pair correlation function and density profile reveal rich information about the equilibrium structure of the film. The strength and equilibrium bond length of finite extensible non-linear elastic potential (FENE) and non-bonding Morse potential have clear impact on microscopic rupturing of the film. The beads show Rouse or repetition motion forming rim like structures near the holes created inside the film. The higher order interaction as dipole-quadrupole may get prominence under strong confinement. The enhanced excluded volume interaction under strong confinement may overlap with the molecular dispersion forces. It can work to reorganize the molecules at the bottom of the scale and can imprint its signature in complex patterns evolved.

MRI-based biomechanical parameters for carotid artery plaque vulnerability assessment.

PubMed

Speelman, Lambert; Teng, Zhongzhao; Nederveen, Aart J; van der Lugt, Aad; Gillard, Jonathan H

2016-03-01

Carotid atherosclerotic plaques are a major cause of ischaemic stroke. The biomechanical environment to which the arterial wall and plaque is subjected to plays an important role in the initiation, progression and rupture of carotid plaques. MRI is frequently used to characterize the morphology of a carotid plaque, but new developments in MRI enable more functional assessment of carotid plaques. In this review, MRI based biomechanical parameters are evaluated on their current status, clinical applicability, and future developments. Blood flow related biomechanical parameters, including endothelial wall shear stress and oscillatory shear index, have been shown to be related to plaque formation. Deriving these parameters directly from MRI flow measurements is feasible and has great potential for future carotid plaque development prediction. Blood pressure induced stresses in a plaque may exceed the tissue strength, potentially leading to plaque rupture. Multi-contrast MRI based stress calculations in combination with tissue strength assessment based on MRI inflammation imaging may provide a plaque stress-strength balance that can be used to assess the plaque rupture risk potential. Direct plaque strain analysis based on dynamic MRI is already able to identify local plaque displacement during the cardiac cycle. However, clinical evidence linking MRI strain to plaque vulnerability is still lacking. MRI based biomechanical parameters may lead to improved assessment of carotid plaque development and rupture risk. However, better MRI systems and faster sequences are required to improve the spatial and temporal resolution, as well as increase the image contrast and signal-to-noise ratio.

Influence of UFG structure formation on mechanical and fatigue properties in Ti-6Al-7Nb alloy

NASA Astrophysics Data System (ADS)

Polyakova, V. V.; Anumalasetty, V. N.; Semenova, I. P.; Valiev, R. Z.

2014-08-01

Ultrafine-grained (UFG) Ti alloys have potential applications in osteosynthesis and orthopedics due to high bio-compatibility and increased weight-to- strength ratio. In current study, Ti6Al7Nb ELI alloy is processed through equal channel angular pressing-conform (ECAP-Conform) and subsequent thermomechanical processing to generate a UFG microstructure. The fatigue properties of UFG alloys are compared to coarse grained (CG) alloys. Our study demonstrates that the UFG alloys with an average grain size of ~180 nm showed 35% enhancement of fatigue endurance limit as compared to coarse-grained alloys. On the fracture surfaces of the UFG and CG samples fatigue striations and dimpled relief were observed. However, the fracture surface of the UFG sample looks smoother; fewer amounts of secondary micro-cracks and more ductile rupture were also observed, which testifies to the good crack resistance in the UFG alloy after high-cyclic fatigue tests.

Adsorption of modified dextrins on molybdenite: AFM imaging, contact angle, and flotation studies.

PubMed

Beaussart, Audrey; Parkinson, Luke; Mierczynska-Vasilev, Agnieszka; Beattie, David A

2012-02-15

The adsorption of three dextrins (a regular wheat dextrin, Dextrin TY, carboxymethyl (CM) Dextrin, and hydroxypropyl (HP) Dextrin) on molybdenite has been investigated using adsorption isotherms, tapping mode atomic force microscopy (TMAFM), contact angle measurements, and dynamic bubble-surface collisions. In addition, the effect of the polymers on the flotation recovery of molybdenite has been determined. The isotherms revealed the importance of molecular weight in determining the adsorbed amounts of the polymers on molybdenite at plateau coverage. TMAFM revealed the morphology of the three polymers, which consisted of randomly dispersed domains with a higher area fraction of surface coverage for the substituted dextrins. The contact angle of polymer-treated molybdenite indicated that polymer layer coverage and hydration influenced the mineral surface hydrophobicity. Bubble-surface collisions indicated that the polymers affected thin film rupture and dewetting rate differently, correlating with differences in the adsorbed layer morphology. Direct correlations were found between the surface coverage of the adsorbed layers, their impact on thin film rupture time, and their impact on flotation recovery, highlighting the paramount role of the polymer morphology in the bubble/particle attachment process and subsequent flotation. Copyright © 2011 Elsevier Inc. All rights reserved.

Intermediate Temperature Strength Degradation in SiC/SiC Composites

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Cawley, James D.; Levine, Stanley (Technical Monitor)

2001-01-01

Woven silicon carbide fiber-reinforced, silicon carbide matrix composites are leading candidate materials for an advanced jet engine combustor liner application. Although the use temperature in the hot region for this application is expected to exceed 1200 C, a potential life-limiting concern for this composite system exists at intermediate temperatures (800 +/- 200 C), where significant time-dependent strength degradation has been observed under stress-rupture loading. A number of factors control the degree of stress-rupture strength degradation, the major factor being the nature of the interphase separating the fiber and the matrix. BN interphases are superior to carbon interphases due to the slower oxidation kinetics of BN. A model for the intermediate temperature stress-rupture of SiC/BN/SiC composites is presented based on the observed mechanistic process that leads to strength degradation for the simple case of through-thickness matrix cracks. The approach taken has much in common with that used by Curtin and coworkers, for two different composite systems. The predictions of the model are in good agreement with the rupture data for stress-rupture of both precracked and as-produced composites. Also, three approaches that dramatically improve the intermediate temperature stress-rupture properties are described: Si-doped BN, fiber spreading, and 'outside debonding'.

Piecemeal Rupture of the Mentawai Patch, Sumatra: The 2008 Mw 7.2 North Pagai Earthquake Sequence

NASA Astrophysics Data System (ADS)

Salman, Rino; Hill, Emma M.; Feng, Lujia; Lindsey, Eric O.; Mele Veedu, Deepa; Barbot, Sylvain; Banerjee, Paramesh; Hermawan, Iwan; Natawidjaja, Danny H.

2017-11-01

The 25 February 2008 Mw 7.2 North Pagai earthquake partially ruptured the middle section of the Mentawai patch of the Sunda megathrust, offshore Sumatra. The patch has been forecast to generate a great earthquake in the next few decades. However, in the current cycle the patch has so far broken in a sequence of partial ruptures, one of which was the 2008 event, illustrating the potential of the patch to generate a spectrum of earthquake sizes. We estimate the coseismic slip distribution of the 2008 event by jointly inverting coseismic offsets from GPS and interferometric synthetic aperture radar. We then estimate afterslip with 5.6 years of cumulative GPS displacements. Our results suggest that the estimated afterslip partially overlaps the coseismic rupture. The overlap of coseismic rupture and afterslip can be explained conceptually by a simple rate-and-state model where the degree of overlapping is controlled by the dynamic weakening and the critical nucleation size in the velocity-weakening area. Comparing our rate-and-state model results with our geodetic inversion results, we suggest that the part of the coseismic rupture that does not overlap with the afterslip may represent a velocity-weakening region, while the overlapping part may represent a velocity-strengthening region.

Geodetic Insights into the Earthquake Cycle in a Fold and Thrust Belt

NASA Astrophysics Data System (ADS)

Ingleby, T. F.; Wright, T. J.; Butterworth, V.; Weiss, J. R.; Elliott, J.

2017-12-01

Geodetic measurements are often sparse in time (e.g. individual interferograms) and/or space (e.g. GNSS stations), adversely affecting our ability to capture the spatiotemporal detail required to study the earthquake cycle in complex tectonic systems such as subaerial fold and thrust belts. In an effort to overcome these limitations we combine 3 generations of SAR satellite data (ERS 1/2, Envisat & Sentinel-1a/b) to obtain a 25 year, high-resolution surface displacement time series over the frontal portion of an active fold and thrust belt near Quetta, Pakistan where a Mw 7.1 earthquake doublet occurred in 1997. With these data we capture a significant portion of the seismic cycle including the interseismic, coseismic and postseismic phases. Each satellite time series has been referenced to the first ERS-1 SAR epoch by fitting a ground deformation model to the data. This allows us to separate deformation associated with each phase and to examine their relative roles in accommodating strain and creating topography, and to explore the relationship between the earthquake cycle and critical taper wedge mechanics. Modeling of the coseismic deformation suggests a long, thin rupture with rupture length 7 times greater than rupture width. Rupture was confined to a 20-30 degree north-northeast dipping reverse fault or ramp at depth, which may be connecting two weak decollements at approximately 8 km and 13 km depth. Alternatively, intersections between the coseismic fault plane and pre-existing steeper splay faults underlying folds may have played a significant role in inhibiting rupture, as evidenced by intersection points bordering the rupture. These fault intersections effectively partition the fault system down-dip and enable long, thin ruptures. Postseismic deformation is manifest as uplift across short-wavelength folds at the thrust front, with displacement rates decreasing with time since the earthquake. Broader patterns of postseismic uplift are also observed surrounding the coseismic rupture in both the down- and up-dip directions. We examine how coseismic stress changes may be driving the postseismic deformation by jointly inverting the InSAR-derived displacements for the rupture and fault friction parameters using a rate-strengthening friction model.

The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust

NASA Astrophysics Data System (ADS)

Kumar, Ajay; Singh, Shashwat K.; Mitra, S.; Priestley, K. F.; Dayal, Shankar

2017-02-01

The 2015 Gorkha earthquake (Mw 7.8) occurred by thrust faulting on a ˜150 km long and ˜70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the main-shock rupture and source mechanism of aftershocks. The main-shock initiated ˜80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards along ˜117° azimuth for a duration of ˜70 s, with varying rupture velocity on a heterogeneous fault surface. The main-shock has been modelled using four subevents, propagating from west-to-east. The first subevent (0-20 s) ruptured at a velocity of ˜3.5 km s- 1 on a ˜6°N dipping flat segment of the MHT with thrust motion. The second subevent (20-35 s) ruptured a ˜18° W dipping lateral ramp on the MHT in oblique thrust motion. The rupture velocity dropped from 3.5 km s- 1 to 2.5 km s- 1, as a result of updip propagation of the rupture. The third subevent (35-50 s) ruptured a ˜7°N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth subevent (50-70 s) occurred by left-lateral strike-slip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the main-shock rupture. Eastward stress build-up following the main-shock resulted in the largest aftershock (Mw 7.3), which occurred on the MHT, immediately east of the main-shock rupture. Source mechanisms of moderate aftershocks reveal stress adjustment at the edges of the main-shock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT.

Intermediate Temperature Stress Rupture of Woven SiC Fiber, BN Interphase, SiC Matrix Composites in Air

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Levine, Stanley (Technical Monitor)

2000-01-01

Tensile stress-rupture experiments were performed on woven Hi-Nicalon reinforced SiC matrix composites with BN interphases in air. Modal acoustic emission (AE) was used to monitor the damage accumulation in the composites during the tests and microstructural analysis was performed to determine the amount of matrix cracking that occurred for each sample. Fiber fractograph), was also performed for individual fiber failures at the specimen fracture surface to determine the strengths at which fibers failed. The rupture strengths were significantly worse than what would have been expected front the inherent degradation of the fibers themselves when subjected to similar rupture conditions. At higher applied stresses the rate of rupture "?as larger than at lower applied stresses. It was observed that the change in rupture rate corresponded to the onset of through-thickness cracking in the composites themselves. The primary cause of the sen,ere degradation was the ease with which fibers would bond to one another at their closest separation distances, less than 100 nanometers, when exposed to the environment. The near fiber-to-fiber contact in the woven tows enabled premature fiber failure over large areas of matrix cracks due to the stress-concentrations created b), fibers bonded to one another after one or a few fibers fail. i.e. the loss of global load sharing. An@, improvement in fiber-to-fiber separation of this composite system should result in improved stress- rupture properties. A model was den,eloped in order to predict the rupture life-time for these composites based on the probabilistic nature of indin,idual fiber failure at temperature. the matrix cracking state during the rupture test, and the rate of oxidation into a matrix crack. Also incorporated into the model were estimates of the stress-concentration that would occur between the outer rim of fibers in a load-bearing bundle and the unbridged region of a matrix crack after Xia et al. For the lower stresses, this source of stress-concentration was the likely cause for initial fiber failure that would trigger catastrophic failure of the composite.

Establishment of borehole observation system and high resolution seismic studies in the western part of the main Marmara Fault in the frame of MARSite Project

NASA Astrophysics Data System (ADS)

Ozel, A.; Yalcinkaya, E.; Guralp, C. M.; Tunc, S.; Meral Ozel, N.

2013-12-01

The main objective of this study is to install a multi-parameter borehole system and surface array as close to the main Marmara Fault (MMF) in the western Marmara Sea as possible, and measure continuously the evolution of the state of the fault zone surrounding the MMF and to detect any anomaly or change which may occur before earthquakes by making use of the data from the arrays already running in the eastern part of the Marmara Sea. The multi-parameter borehole system will be composed of very wide dynamic range and stable borehole (VBB) broad band seismic sensor, and incorporate 3-D strain meter, tilt meter, and temperature and local hydrostatic pressure measuring devices. The borehole seismic station will use the latest update technologies and design ideas to record 'Earth tides' signals to the smallest magnitude -3 events. Bringing face to face the seismograms of microearthquakes recorded by borehole and surface instruments portrays quite different contents. The shorter recording duration and nearly flat frequency spectrum up to the Nyquist frequencies of borehole records are faced with longer recording duration and rapid decay of spectral amplitudes at higher frequencies of a surface seismogram. The main causative of the observed differences are near surface geology effects that mask most of the source related information the seismograms include, and that give rise to scattering, generating longer duration seismograms. In view of these circumstances, studies on microearthquakes employing surface seismograms may bring on misleading results. Particularly, the works on earthquake physics and nucleation process of earthquakes requires elaborate analysis of tiny events. It is obvious from the studies on the nucleation process of the 1999 earthquake that tens of minutes before the major rupture initiate noteworthy microearthquake activity happened. The starting point of the 1999 rupture was a site of swarm activity noticed a few decades prior the main shock. Nowadays, analogous case is probable in western Marmara Sea region, prone to a major event in near future where the seismic activity is prevailing along the impending rupture zone. Deploying a borehole system eastern end of the Ganos fault zone may yield invaluable data to closely inspect and monitor the last stages of the preparation stage of major rupture. Keywords: Borehole seismometer; Ganos fault; microearthquakes; western Marmara

Coherent to incoherent transition of precipitates during rupture test in TP347H austenitic stainless steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Chang-Whan; Heo, Yoon-Uk, E-mail: yunuk01@postech.ac.kr; Heo, Nam-Hoe

2016-05-15

Precipitation of various particles and their growth during rupture test have been investigated in TP347H austenitic stainless steels using a transmission electron microscopy. Various precipitates of MnS, Nb-rich MC, and MnS + MC and MnS + M{sub 2}P complexes are observed in the γ matrix after rupture test at 750 °C. The MnS particles formed independently in the γ matrix show a coherency or semi-coherency with the γ matrix. The Nb-rich MC carbides show also a coherency with the γ matrix. The Nb-rich MC carbides showing a semi-coherency with the MnS also form on the surface of the coherent ormore » semi-coherent MnS particles, and they show a cube-cube orientation relationship with the MnS particles. The MnS + MC complex loses the initial coherency with the γ matrix, as the MC in the complex grows. The Nb-rich M{sub 2}P precipitates formed on the surface of the MnS particles do not show an orientation relationship with the MnS particles or the γ matrix. The MnS particles in the MnS + M{sub 2}P complex hold the initial coherency with the γ matrix. Effects of MnS precipitation followed by the formation of the complexes on rupture life of the TP347H austenitic stainless steels are discussed from the viewpoint of MnS precipitates acting as sinks of free sulfur segregating to the grain boundaries. - Highlights: • Coherent to incoherent transition of precipitates during rupture test in TP347H steels is clarified. • MnS precipitation actively retards the time to intergranular fracture. • Effect of the coherency of secondary precipitates on the coherency loss of the complex particle is compared.« less

Variations in rupture process with recurrence interval in a repeated small earthquake

USGS Publications Warehouse

Vidale, J.E.; Ellsworth, W.L.; Cole, A.; Marone, Chris

1994-01-01

In theory and in laboratory experiments, friction on sliding surfaces such as rock, glass and metal increases with time since the previous episode of slip. This time dependence is a central pillar of the friction laws widely used to model earthquake phenomena. On natural faults, other properties, such as rupture velocity, porosity and fluid pressure, may also vary with the recurrence interval. Eighteen repetitions of the same small earthquake, separated by intervals ranging from a few days to several years, allow us to test these laboratory predictions in situ. The events with the longest time since the previous earthquake tend to have about 15% larger seismic moment than those with the shortest intervals, although this trend is weak. In addition, the rupture durations of the events with the longest recurrence intervals are more than a factor of two shorter than for the events with the shortest intervals. Both decreased duration and increased friction are consistent with progressive fault healing during the time of stationary contact.In theory and in laboratory experiments, friction on sliding surfaces such as rock, glass and metal increases with time since the previous episode of slip. This time dependence is a central pillar of the friction laws widely used to model earthquake phenomena. On natural faults, other properties, such as rupture velocity, porosity and fluid pressure, may also vary with the recurrence interval. Eighteen repetitions of the same small earthquake, separated by intervals ranging from a few days to several years, allow us to test these laboratory predictions in situ. The events with the longest time since the previous earthquake tend to have about 15% larger seismic moment than those with the shortest intervals, although this trend is weak. In addition, the rupture durations of the events with the longest recurrence intervals are more than a factor of two shorter than for the events with the shortest intervals. Both decreased duration and increased friction are consistent with progressive fault healing during the time of stationary contact.

Misbheaving Faults: The Expanding Role of Geodetic Imaging in Unraveling Unexpected Fault Slip Behavior

NASA Astrophysics Data System (ADS)

Barnhart, W. D.; Briggs, R.

2015-12-01

Geodetic imaging techniques enable researchers to "see" details of fault rupture that cannot be captured by complementary tools such as seismology and field studies, thus providing increasingly detailed information about surface strain, slip kinematics, and how an earthquake may be transcribed into the geological record. For example, the recent Haiti, Sierra El Mayor, and Nepal earthquakes illustrate the fundamental role of geodetic observations in recording blind ruptures where purely geological and seismological studies provided incomplete views of rupture kinematics. Traditional earthquake hazard analyses typically rely on sparse paleoseismic observations and incomplete mapping, simple assumptions of slip kinematics from Andersonian faulting, and earthquake analogs to characterize the probabilities of forthcoming ruptures and the severity of ground accelerations. Spatially dense geodetic observations in turn help to identify where these prevailing assumptions regarding fault behavior break down and highlight new and unexpected kinematic slip behavior. Here, we focus on three key contributions of space geodetic observations to the analysis of co-seismic deformation: identifying near-surface co-seismic slip where no easily recognized fault rupture exists; discerning non-Andersonian faulting styles; and quantifying distributed, off-fault deformation. The 2013 Balochistan strike slip earthquake in Pakistan illuminates how space geodesy precisely images non-Andersonian behavior and off-fault deformation. Through analysis of high-resolution optical imagery and DEMs, evidence emerges that a single fault map slip as both a strike slip and dip slip fault across multiple seismic cycles. These observations likewise enable us to quantify on-fault deformation, which account for ~72% of the displacements in this earthquake. Nonetheless, the spatial distribution of on- and off-fault deformation in this event is highly spatially variable- a complicating factor for comparisons of geologic and geodetic slip rates. As such, detailed studies such as this will play a continuing vital role in the accurate assessment of short- and long-term fault slip kinematics.

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

PubMed

Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

2016-09-15

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (<20nm thick) were mainly investigated by atomic force microscopy. Surface chemical analysis of the ultrathin films annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. Copyright © 2016 Elsevier Inc. All rights reserved.

Morphological evolution of thin polymer film on chemically patterned substrates

NASA Astrophysics Data System (ADS)

Singh, Satya Pal

2018-05-01

In this paper work, pattern formation in ultra thin polymer film, adsorbed on chemically patterned substrates, is reported under strong confinement. The observations indicate for the strong influence of the surface attraction over evolution of spindoal waves, leading to the flattening of the film. But, the film appears to be torn apart in strip or nano fiber like structures, because of coalescences of the monomers at the free ends of the chains. The beads at the free ends of the chain are relatively more mobile. The chain diffusion towards attractive part of the chemically patterned surfaces is clearly seen. Prewetting or crystallization like phenomena seems to appear resulting into formation of strips with coexistence of molten phase drops at the top of the ruptured film. The investigation mimics spindoal dewetting because of the fact that the rupturing occurs in case of strong attractive surface. The investigation is of technical importance as it highlights the formation of nano scale strips and fibers though in a quasi equilibrium case.

Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit.

PubMed

Fialko, Yuri; Sandwell, David; Simons, Mark; Rosen, Paul

2005-05-19

Our understanding of the earthquake process requires detailed insights into how the tectonic stresses are accumulated and released on seismogenic faults. We derive the full vector displacement field due to the Bam, Iran, earthquake of moment magnitude 6.5 using radar data from the Envisat satellite of the European Space Agency. Analysis of surface deformation indicates that most of the seismic moment release along the 20-km-long strike-slip rupture occurred at a shallow depth of 4-5 km, yet the rupture did not break the surface. The Bam event may therefore represent an end-member case of the 'shallow slip deficit' model, which postulates that coseismic slip in the uppermost crust is systematically less than that at seismogenic depths (4-10 km). The InSAR-derived surface displacement data from the Bam and other large shallow earthquakes suggest that the uppermost section of the seismogenic crust around young and developing faults may undergo a distributed failure in the interseismic period, thereby accumulating little elastic strain.

Study on conditional probability of surface rupture: effect of fault dip and width of seismogenic layer

NASA Astrophysics Data System (ADS)

Inoue, N.

2017-12-01

The conditional probability of surface ruptures is affected by various factors, such as shallow material properties, process of earthquakes, ground motions and so on. Toda (2013) pointed out difference of the conditional probability of strike and reverse fault by considering the fault dip and width of seismogenic layer. This study evaluated conditional probability of surface rupture based on following procedures. Fault geometry was determined from the randomly generated magnitude based on The Headquarters for Earthquake Research Promotion (2017) method. If the defined fault plane was not saturated in the assumed width of the seismogenic layer, the fault plane depth was randomly provided within the seismogenic layer. The logistic analysis was performed to two data sets: surface displacement calculated by dislocation methods (Wang et al., 2003) from the defined source fault, the depth of top of the defined source fault. The estimated conditional probability from surface displacement indicated higher probability of reverse faults than that of strike faults, and this result coincides to previous similar studies (i.e. Kagawa et al., 2004; Kataoka and Kusakabe, 2005). On the contrary, the probability estimated from the depth of the source fault indicated higher probability of thrust faults than that of strike and reverse faults, and this trend is similar to the conditional probability of PFDHA results (Youngs et al., 2003; Moss and Ross, 2011). The probability of combined simulated results of thrust and reverse also shows low probability. The worldwide compiled reverse fault data include low fault dip angle earthquake. On the other hand, in the case of Japanese reverse fault, there is possibility that the conditional probability of reverse faults with less low dip angle earthquake shows low probability and indicates similar probability of strike fault (i.e. Takao et al., 2013). In the future, numerical simulation by considering failure condition of surface by the source fault would be performed in order to examine the amount of the displacement and conditional probability quantitatively.

Structure of a seismogenic fault zone in dolostones: the Foiana Line (Italian Southern Alps)

NASA Astrophysics Data System (ADS)

Di Toro, G.; Fondriest, M.; Smith, S. A.; Aretusini, S.

2012-12-01

Fault zones in carbonate rocks (limestones and dolostones) represent significant upper crustal seismogenic sources in several areas worldwide (e.g. L'Aquila 2009 Mw = 6.3 in central Italy). Here we describe an exhumed example of a regionally-significant fault zone cutting dolostones. The Foiana Line (FL) is a major NNE-SSW-trending sinistral transpressive fault cutting sedimentary Triassic dolostones in the Italian Southern Alps. The FL has a cumulative vertical throw of 1.5-2 km that reduces toward its southern termination. The fault zone is 50-300 m wide and is exposed for ~ 10 km along strike within several outcrops exhumed from increasing depths from the south (1 km) to the north (2.5 km). The southern portion of the FL consists of heavily fractured (shattered) dolostones, with particles of a few millimeters in size (exposed in badlands topography over an area of 6 km2), cut by a dense network of 1-20 m long mirror-like fault surfaces with dispersed attitudes. The mirror-like faults have mainly dip-slip reverse kinematics and displacements ranging between 0.04 m and 0.5 m. The northern portion of the FL consists of sub-parallel fault strands spaced 2-5 m apart, surrounded by 2-3 m thick bands of shattered dolostones. The fault strands are characterized by smooth to mirror-like sub-vertical slip surfaces with dominant strike-slip kinematics. Overall, deformation is more localized moving from South to North along the FL. Mirror-like fault surfaces similar to those found in the FL were produced in friction experiments at the deformation conditions expected during seismic slip along the FL (Fondriest et al., this meeting). Scanning Electron Microscope investigations of the natural shattered dolostones beneath the mirror-like fault surfaces show: 1) lack of significant shear strain (even at a few micrometers from the slip surface), 2) pervasive extensional fracturing down to the micrometer scale, 3) exploded clasts with radial fractures, and 4) chains of split clasts (resulting from force chains) oriented at 60-80 degrees to the slip surfaces. Similar features have been reported in natural and experimental pulverized rocks, the latter produced under dynamic stress wave loading conditions. 3-Dimensional rupture simulations along strike-slip faults predict (1) off-fault damage distributions with "flower-like" shapes (broad damage zone near the surface that rapidly narrows with increasing confining pressure, e.g., Ma and Andrews, 2010) and (2) formation of secondary faults/fractures with disperse attitudes and kinematics near the surface, with horizontal slip at depth. Qualitatively, these theoretical results compare favorably with increasing strain localization and a switch in fault kinematics recognized along the FL moving from the southern, shallower portion of the fault zone to the northern, deeper portion. Observations along the FL suggest that the association of shattered dolostones and mirror-like slip surfaces might be a potential indicator of seismic rupture propagation. Further detailed structural mapping along the FL coupled with experimental work on rock pulverization will be necessary to understand rupture dynamics in dolostones.

Kinematic ground motion simulations on rough faults including effects of 3D stochastic velocity perturbations

USGS Publications Warehouse

Graves, Robert; Pitarka, Arben

2016-01-01

We describe a methodology for generating kinematic earthquake ruptures for use in 3D ground‐motion simulations over the 0–5 Hz frequency band. Our approach begins by specifying a spatially random slip distribution that has a roughly wavenumber‐squared fall‐off. Given a hypocenter, the rupture speed is specified to average about 75%–80% of the local shear wavespeed and the prescribed slip‐rate function has a Kostrov‐like shape with a fault‐averaged rise time that scales self‐similarly with the seismic moment. Both the rupture time and rise time include significant local perturbations across the fault surface specified by spatially random fields that are partially correlated with the underlying slip distribution. We represent velocity‐strengthening fault zones in the shallow (<5  km) and deep (>15  km) crust by decreasing rupture speed and increasing rise time in these regions. Additional refinements to this approach include the incorporation of geometric perturbations to the fault surface, 3D stochastic correlated perturbations to the P‐ and S‐wave velocity structure, and a damage zone surrounding the shallow fault surface characterized by a 30% reduction in seismic velocity. We demonstrate the approach using a suite of simulations for a hypothetical Mw 6.45 strike‐slip earthquake embedded in a generalized hard‐rock velocity structure. The simulation results are compared with the median predictions from the 2014 Next Generation Attenuation‐West2 Project ground‐motion prediction equations and show very good agreement over the frequency band 0.1–5 Hz for distances out to 25 km from the fault. Additionally, the newly added features act to reduce the coherency of the radiated higher frequency (f>1  Hz) ground motions, and homogenize radiation‐pattern effects in this same bandwidth, which move the simulations closer to the statistical characteristics of observed motions as illustrated by comparison with recordings from the 1979 Imperial Valley earthquake.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graves, Robert; Pitarka, Arben

Here, we describe a methodology for generating kinematic earthquake ruptures for use in 3D ground–motion simulations over the 0–5 Hz frequency band. Our approach begins by specifying a spatially random slip distribution that has a roughly wavenumber–squared fall–off. Given a hypocenter, the rupture speed is specified to average about 75%–80% of the local shear wavespeed and the prescribed slip–rate function has a Kostrov–like shape with a fault–averaged rise time that scales self–similarly with the seismic moment. Both the rupture time and rise time include significant local perturbations across the fault surface specified by spatially random fields that are partially correlatedmore » with the underlying slip distribution. We represent velocity–strengthening fault zones in the shallow (<5 km) and deep (>15 km) crust by decreasing rupture speed and increasing rise time in these regions. Additional refinements to this approach include the incorporation of geometric perturbations to the fault surface, 3D stochastic correlated perturbations to the P– and S–wave velocity structure, and a damage zone surrounding the shallow fault surface characterized by a 30% reduction in seismic velocity. We demonstrate the approach using a suite of simulations for a hypothetical Mw 6.45 strike–slip earthquake embedded in a generalized hard–rock velocity structure. The simulation results are compared with the median predictions from the 2014 Next Generation Attenuation–West2 Project ground–motion prediction equations and show very good agreement over the frequency band 0.1–5 Hz for distances out to 25 km from the fault. Additionally, the newly added features act to reduce the coherency of the radiated higher frequency (f>1 Hz) ground motions, and homogenize radiation–pattern effects in this same bandwidth, which move the simulations closer to the statistical characteristics of observed motions as illustrated by comparison with recordings from the 1979 Imperial Valley earthquake.« less

Kinematic Ground-Motion Simulations on Rough Faults Including Effects of 3D Stochastic Velocity Perturbations

DOE PAGES

Graves, Robert; Pitarka, Arben

2016-08-23

Here, we describe a methodology for generating kinematic earthquake ruptures for use in 3D ground–motion simulations over the 0–5 Hz frequency band. Our approach begins by specifying a spatially random slip distribution that has a roughly wavenumber–squared fall–off. Given a hypocenter, the rupture speed is specified to average about 75%–80% of the local shear wavespeed and the prescribed slip–rate function has a Kostrov–like shape with a fault–averaged rise time that scales self–similarly with the seismic moment. Both the rupture time and rise time include significant local perturbations across the fault surface specified by spatially random fields that are partially correlatedmore » with the underlying slip distribution. We represent velocity–strengthening fault zones in the shallow (<5 km) and deep (>15 km) crust by decreasing rupture speed and increasing rise time in these regions. Additional refinements to this approach include the incorporation of geometric perturbations to the fault surface, 3D stochastic correlated perturbations to the P– and S–wave velocity structure, and a damage zone surrounding the shallow fault surface characterized by a 30% reduction in seismic velocity. We demonstrate the approach using a suite of simulations for a hypothetical Mw 6.45 strike–slip earthquake embedded in a generalized hard–rock velocity structure. The simulation results are compared with the median predictions from the 2014 Next Generation Attenuation–West2 Project ground–motion prediction equations and show very good agreement over the frequency band 0.1–5 Hz for distances out to 25 km from the fault. Additionally, the newly added features act to reduce the coherency of the radiated higher frequency (f>1 Hz) ground motions, and homogenize radiation–pattern effects in this same bandwidth, which move the simulations closer to the statistical characteristics of observed motions as illustrated by comparison with recordings from the 1979 Imperial Valley earthquake.« less

Surface faulting and paleoseismic history of the 1932 Cedar Mountain earthquake area, west-central Nevada, and implications for modern tectonics of the Walker Lane

USGS Publications Warehouse

Bell, J.W.; DePolo, C.M.; Ramelli, A.R.; Sarna-Wojcicki, A. M.; Meyer, C.E.

1999-01-01

The 1932 Cedar Mountain earthquake (Ms 7.2) was one of the largest historical events in the Walker Lane region of western Nevada, and it produced a complicated strike-slip rupture pattern on multiple Quaternary faults distributed through three valleys. Primary, right-lateral surface ruptures occurred on north-striking faults in Monte Cristo Valley; small-scale lateral and normal offsets occurred in Stewart Valley; and secondary, normal faulting occurred on north-northeast-striking faults in the Gabbs Valley epicentral region. A reexamination of the surface ruptures provides new displacement and fault-zone data: maximum cumulative offset is estimated to be 2.7 m, and newly recognized faults extend the maximum width and end-to-end length of the rupture zone to 17 and 75 km, respectively. A detailed Quaternary allostratigraphic chronology based on regional alluvialgeomorphic relationships, tephrochronology, and radiocarbon dating provides a framework for interpreting the paleoseismic history of the fault zone. A late Wisconsinan alluvial-fan and piedmont unit containing a 32-36 ka tephra layer is a key stratigraphic datum for paleoseismic measurements. Exploratory trenching and radiocarbon dating of tectonic stratigraphy provide the first estimates for timing of late Quaternary faulting along the Cedar Mountain fault zone. Three trenches display evidence for six faulting events, including that in 1932, during the past 32-36 ka. Radiocarbon dating of organic soils interstratified with tectonically ponded silts establishes best-fit ages of the pre-1932 events at 4, 5,12,15, and 18 ka, each with ??2 ka uncertainties. On the basis of an estimated cumulative net slip of 6-12 m for the six faulting events, minimum and maximum late Quaternary slip rates are 0.2 and 0.7 mm/yr, respectively, and the preferred rate is 0.4-0.5 mm/yr. The average recurrence (interseismic) interval is 3600 yr. The relatively uniform thickness of the ponded deposits suggests that similar-size, characteristic rupture events may characterize late Quaternary slip on the zone. A comparison of event timing with the average late Quaternary recurrence interval indicates that slip has been largely regular (periodic) rather than temporally clustered. To account for the spatial separation of the primary surface faulting in Monte Cristo Valley from the epicenter and for a factor-of-two-to-three disparity between the instrumentally and geologically determined seismic moments associated with the earthquake, we hypothesize two alternative tectonic models containing undetected subevents. Either model would adequately account for the observed faulting on the basis of wrench-fault kinematics that may be associated with the Walker Lane. The 1932 Cedar Mountain earthquake is considered an important modern analogue for seismotectonic modeling and estimating seismic hazard in the Walker Lane region. In contrast to most other historical events in the Basin and Range province, the 1932 event did not occur along a major range-bounding fault, and no single, throughgoing basement structure can account for the observed rupture pattern. The 1932 faulting supports the concept that major earthquakes in the Basin and Range province can exhibit complicated distributive rupture patterns and that slip rate may not be a reliable criterion for modeling seismic hazard.

Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Jiaqi; Dang, Liem X.; Miller, Jan D.

Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, themore » film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.« less

Detailed Mapping of Historical and Preinstrumental Earthquake Ruptures in Central Asia Using Multi-Scale, Multi-Platform Photogrammetry

NASA Astrophysics Data System (ADS)

Elliott, A. J.; Walker, R. T.; Parsons, B.; Ren, Z.; Ainscoe, E. A.; Abdrakhmatov, K.; Mackenzie, D.; Arrowsmith, R.; Gruetzner, C.

2016-12-01

In regions of the planet with long historical records, known past seismic events can be attributed to specific fault sources through the identification and measurement of single-event scarps in high-resolution imagery and topography. The level of detail captured by modern remote sensing is now sufficient to map and measure complete earthquake ruptures that were originally only sparsely mapped or overlooked entirely. We can thus extend the record of mapped earthquake surface ruptures into the preinstrumental period and capture the wealth of information preserved in the numerous historical earthquake ruptures throughout regions like Central Asia. We investigate two major late 19th and early 20th century earthquakes that are well located macroseismically but whose fault sources had proved enigmatic in the absence of detailed imagery and topography. We use high-resolution topographic models derived from photogrammetry of satellite, low-altitude, and ground-based optical imagery to map and measure the coseismic scarps of the 1889 M8.3 Chilik, Kazakhstan and 1932 M7.6 Changma, China earthquakes. Measurement of the scarps on the combined imagery and topography reveals the extent and slip distribution of coseismic rupture in each of these events, showing both earthquakes involved multiple faults with variable kinematics. We use a 1-m elevation model of the Changma fault derived from Pleiades satellite imagery to map the changing kinematics of the 1932 rupture along strike. For the 1889 Chilik earthquake we use 1.5-m SPOT-6 satellite imagery to produce a regional elevation model of the fault ruptures, from which we identify three distinct, intersecting fault systems that each have >20 km of fresh, single-event scarps. Along sections of each of these faults we construct high resolution (330 points per sq m) elevation models using quadcopter- and helikite-mounted cameras. From the detailed topography we measure single-event oblique offsets of 6-10 m, consistent with the large inferred magnitude of the 1889 Chilik event. High resolution, photogrammetric topography offers a low-cost, effective way to thoroughly map rupture traces and measure coseismic displacements for past fault ruptures, extending our record of coseismic displacements into a past rich with formerly sparsely documented ruptures.

Measuring the Coseismic Displacements of 2010 Ms7.1 Yushu Earthquake by Using SAR and High Resolution Optical Satellite Images

NASA Astrophysics Data System (ADS)

Zhang, L.; Wu, J.; Shi, F.

2017-09-01

After the 2010, Mw7.1, Yushu earthquake, many researchers have conducted detail investigations of the surface rupture zone by optical image interpretation, field surveying and inversion of seismic waves. However, how larger of the crustal deformation area caused by the earthquake and the quantitative co-seismic displacements are still not available. In this paper, we first take advantage of D-InSAR, MAI, and optical image matching methods to determine the whole co-seismic displacement fields. Two PALSAR images and two SPOT5 images before and after the earthquake are processed and the co-seismic displacements at the surface rupture zone and far field are obtained. The results are consistent with the field investigations, which illustrates the rationality of the application of optical image matching technology in the earthquake.

Expectable Earthquakes and their ground motions in the Van Norman Reservoirs Area

USGS Publications Warehouse

Wesson, R.L.; Page, R.A.; Boore, D.M.; Yerkes, R.F.

1974-01-01

The upper and lower Van Norman dams, in northwesternmost San Fernando Valley about 20 mi (32 km) northwest of downtown Los Angeles, were severely damaged during the 1971 San Fernando earthquake. An investigation of the geologic-seismologic setting of the Van Norman area indicates that an earthquake of at least M 7.7 may be expected in the Van Norman area. The expectable transitory effects in the Van Norman area of such an earthquake are as follows: peak horizontal acceleration of at least 1.15 g, peak velocity of displacement of 4.43 ft/sec (135 cm/sec), peak displacement of 2.3 ft (70 cm), and duration of shaking at accelerations greater than 0.05 g, 40 sec. A great earthquake (M 8+) on the San Andreas fault, 25 mi distant, also is expectable. Transitory effects in the Van Norman area from such an earthquake are estimated as follows: peak horizontal acceleration of 0.5 g, peak velocity of 1.97 ft/sec (60 cm/sec), displacement of 1.31 ft (40 cm), and duration of shaking at accelerations greater than 0.05 g, 80 sec. The permanent effects of the expectable local earthquake could include simultaneous fault movement at the lower damsite, the upper damsite, and the site proposed for a replacement dam halfway between the upper and lower dams. The maximum differential displacements due to such movements are estimated at 16.4 ft (5 m) at the lower damsite and about 9.6 ft (2.93 m) at the upper and proposed damsites. The 1971 San Fernando earthquake (M 6?) was accompanied by the most intense ground motions ever recorded instrumentally for a natural earthquake. At the lower Van Norman dam, horizontal accelerations exceeded 0.6 g, and shaking greater than 0.25 g lasted for about 13 see; at Pacoima dam, 6 mi (10 km) northeast of the lower dam, high-frequency peak horizontal accelerations of 1.25 g were recorded in two directions, and shaking greater than 0.25 g lasted for about 7 sec. Permanent effects of the earthquake include slope failures in the embankments of the upper and lower Van Norman dams, rupturing of the ground surface by faulting along parts of the zone of old faults that extends easterly through the reservoir area and across the northern part of the valley, folding or arching of the ground surface, and differential horizontal displacement of the terrane north and south of the fault zone. Although a zone of old faults extends through the reservoir area, the 1971 surface ruptures apparently did not; however, arching and horizontal displacements caused small relative displacements of the abutment areas of each of the three damsites. The 1971 arching coincided with preexisting topographic highs, and the surface ruptures coincided with eroded fault scarps and a buried ground-water impediment formed by pre-1971 faulting in young valley fill. This coincidence with evidence of past deformation indicates that the 1971 deformations were the result of a continuing geologic process that is expected to produce similar deformations during future events. The 1971 San Fernando earthquake probably was not the largest that has occurred in this area during the last approximately 200 years, as indicated by a buried fault like scarp about 200 years old that is higher than, and aligned with, 1971 fault scarps. In addition, the San Fernando zone of 1971 ruptures is part of a regional tectonic system that includes the San Andreas and associated faults; one of these, the White Wolf fault north of the San Andreas, is symmetrical in structural attitude with the San Fernando zone and ruptured the ground surface during the 1952 Kern County earthquake (M 7.7). Other large earthquakes associated with surface rupturing on faults of this system include the 1857 Fort Tejon earthquake (M 8+) and possibly the 1852 Big Pine earthquake. Several other historic earthquakes in this general area are not known to be associated with surface ruptures, but were large enough to cause damage in the northern San Fernando Valley. The Van Norman rese

Geologic environment of the Van Norman Reservoirs area

USGS Publications Warehouse

Yerkes, R.F.; Bonilla, M.G.; Youd, T.L.; Sims, J.D.

1974-01-01

The upper and lower Van Norman dams, in northwesternmost San Fernando Valley about 20 mi (32 km) northwest of downtown Los Angeles, were severely damaged during the 1971 San Fernando earthquake. An investigation of the geologic-seismologic setting of the Van Norman area indicates that an earthquake of at least M 7.7 may be expected in the Van Norman area. The expectable transitory effects in the Van Norman area of such an earthquake are as follows: peak horizontal acceleration of at least 1.15 g, peak velocity of displacement of 4.43 ft/sec (135 cm/sec), peak displacement of 2.3 ft (70 cm), and duration of shaking at accelerations greater than 0.05 g, 40 sec. A great earthquake (M 8+) on the San Andreas fault, 25 mi distant, also is expectable. Transitory effects in the Van Norman area from such an earthquake are estimated as follows: peak horizontal acceleration of 0.5 g, peak velocity of 1.97 ft/sec (60 cm/sec), displacement of 1.31 ft (40 cm), and duration of shaking at accelerations greater than 0.05 g, 80 sec. The permanent effects of the expectable local earthquake could include simultaneous fault movement at the lower damsite, the upper damsite, and the site proposed for a replacement dam halfway between the upper and lower dams. The maximum differential displacements due to such movements are estimated at 16.4 ft (5 m) at the lower damsite and about 9.6 ft (2.93 m) at the upper and proposed damsites. The 1971 San Fernando earthquake (M 6?) was accompanied by the most intense ground motions ever recorded instrumentally for a natural earthquake. At the lower Van Norman dam, horizontal accelerations exceeded 0.6 g, and shaking greater than 0.25 g lasted for about 13 see; at Pacoima dam, 6 mi (10 km) northeast of the lower dam, high-frequency peak horizontal accelerations of 1.25 g were recorded in two directions, and shaking greater than 0.25 g lasted for about 7 sec. Permanent effects of the earthquake include slope failures in the embankments of the upper and lower Van Norman dams, rupturing of the ground surface by faulting along parts of the zone of old faults that extends easterly through the reservoir area and across the northern part of the valley, folding or arching of the ground surface, and differential horizontal displacement of the terrane north and south of the fault zone. Although a zone of old faults extends through the reservoir area, the 1971 surface ruptures apparently did not; however, arching and horizontal displacements caused small relative displacements of the abutment areas of each of the three damsites. The 1971 arching coincided with preexisting topographic highs, and the surface ruptures coincided with eroded fault scarps and a buried ground-water impediment formed by pre-1971 faulting in young valley fill. This coincidence with evidence of past deformation indicates that the 1971 deformations were the result of a continuing geologic process that is expected to produce similar deformations during future events. The 1971 San Fernando earthquake probably was not the largest that has occurred in this area during the last approximately 200 years, as indicated by a buried fault like scarp about 200 years old that is higher than, and aligned with, 1971 fault scarps. In addition, the San Fernando zone of 1971 ruptures is part of a regional tectonic system that includes the San Andreas and associated faults; one of these, the White Wolf fault north of the San Andreas, is symmetrical in structural attitude with the San Fernando zone and ruptured the ground surface during the 1952 Kern County earthquake (M 7.7). Other large earthquakes associated with surface rupturing on faults of this system include the 1857 Fort Tejon earthquake (M 8+) and possibly the 1852 Big Pine earthquake. Several other historic earthquakes in this general area are not known to be associated with surface ruptures, but were large enough to cause damage in the northern San Fernando Valley. The Van Norman rese

The Emilia 2012 seismic sequence: hints on incipient basement-involved deformation in the foreland of the Northern Apennines (Italy)

NASA Astrophysics Data System (ADS)

Argnani, Andrea; Carannante, Simona; Massa, Marco; D'Alema, Ezio; Lovati, Sara

2015-04-01

The deformation front of the Northern Apennines is buried under the sediments of the Po Plain and was formed mainly during the Pliocene. The remarkably arcuate shape of the thrust front contrasts with the linear northwestern trend of the pede-Apennines, where recent deformation is documented by both geological and geodetic evidence. This study presents new geological and seismological data that are used to assess the structural style of the Ferrara Arc, a sector of the Northern Apennine front that was hit by two strong earthquakes on May 20 (MW 6.1) and May 29 (MW 6.0), 2012. The proposed interpretation is based on a dense grid of commercial seismic profiles and exploration wells, and high-quality relocation of ~5,300 earthquakes (the Emilia sequence). The seismicity was used to calibrate new one-dimensional and three-dimensional local Vp and Vs velocity models for the area. On the basis of these new models, the initial sparse hypocenters were then relocated in absolute mode and adjusted using the double-difference relative location algorithm. Seismicity distribution is elongated in the W-NW to E-SE directions, reaching a depth of 10-12 km. The aftershocks of the May 20 mainshock appear to be distributed on a rupture surface that dips ~45° SSW, and the surface projection indicates an area ~10 km wide and 23 km long. The aftershocks of the May 29 second mainshock followed a steep rupture surface that is well constrained within the investigated volume, whereby the surface projection of the blind source indicates an area ~6 km wide and 33 km long. The analysed multichannel seismic profiles highlight the presence of relevant lateral variations in the structural style of the Ferrara folds that developed during the Pliocene and Pleistocene, and also show the occurrence of a Mesozoic extensional fault system in the Ferrara arc, which in places has been seismically reactivated. These geological and seismological observations suggest that the 2012 Emilia earthquakes were related to ruptures along blind fault surfaces that are not part of the Pliocene-Pleistocene structural system, but are instead related to a deeper system that is itself closely related to re-activation of a Mesozoic extensional fault system. The implication is that the Emilia 2012 seismic sequence was related to activation of a new deformation system that has developed since the late Pleistocene and that affects the deeper structural levels within the Adriatic crust. This interpretation has major relevance for the seismotectonic characterization of the Po Plain, because the location and extent of the Ferrara folds, that were formed during the Pliocene-Pleistocene, cannot simply be used to estimate the seismogenic potential of the Ferrara Arc region.

Structure and mechanics of the Hayward-Rodgers Creek Fault step-over, San Francisco Bay, California

USGS Publications Warehouse

Parsons, T.; Sliter, R.; Geist, E.L.; Jachens, R.C.; Jaffe, B.E.; Foxgrover, A.; Hart, P.E.; McCarthy, J.

2003-01-01

A dilatational step-over between the right-lateral Hayward and Rodgers Creek faults lies beneath San Pablo Bay in the San Francisco Bay area. A key seismic hazard issue is whether an earthquake on one of the faults could rupture through the step-over, enhancing its maximum possible magnitude. If ruptures are terminated at the step-over, then another important issue is how strain transfers through the step. We developed a combined seismic reflection and refraction cross section across south San Pablo Bay and found that the Hayward and Rodgers Creek faults converge to within 4 km of one another near the surface, about 2 km closer than previously thought. Interpretation of potential field data from San Pablo Bay indicated a low likelihood of strike-slip transfer faults connecting the Hayward and Rodgers Creek faults. Numerical simulations suggest that it is possible for a rupture to jump across a 4-km fault gap, although special stressing conditions are probably required (e.g., Harris and Day, 1993, 1999). Slip on the Hayward and Rodgers Creek faults is building an extensional pull-apart basin that could contain hazardous normal faults. We investigated strain in the pull-apart using a finite-element model and calculated a ???0.02-MPa/yr differential stressing rate in the step-over on a least-principal-stress orientation nearly parallel to the strike-slip faults where they overlap. A 1- to 10-MPa stress-drop extensional earthquake is expected on normal faults oriented perpendicular to the strike-slip faults every 50-500 years. The last such earthquake might have been the 1898 M 6.0-6.5 shock in San Pablo Bay that apparently produced a small tsunami. Historical hydrographic surveys gathered before and after 1898 indicate abnormal subsidence of the bay floor within the step-over, possibly related to the earthquake. We used a hydrodynamic model to show that a dip-slip mechanism in north San Pablo Bay is the most likely 1898 rupture scenario to have caused the tsunami. While we find no strike-slip transfer fault between the Hayward and Rodgers Creek faults, a normal-fault link could enable through-going segmented rupture of both strike-slip faults and may pose an independent hazard of M ???6 earthquakes like the 1898 event.

Mesenchymal stem cells reside in anterior cruciate ligament remnants in situ.

PubMed

Fu, Weili; Li, Qi; Tang, Xin; Chen, Gang; Zhang, Chenghao; Li, Jian

2016-07-01

It has been reported that the anterior cruciate ligament (ACL) has certain self-healing ability after acute injury or with primary suture repair. Many studies have confirmed that a remnant preservation technique with ACL reconstruction contributes to biological augmentation for ACL healing. However, it remains unclear whether mesenchymal stem cells (MSC) reside in ACL remnants in situ. The aim of this study was to investigate the methods of culture and identification of MSC derived from the remnants of ACL rupture patients and to analyse these MSC's properties. The cells of ACL remnants from the ACL rupture patients were isolated by the methods of enzymatic digestion and cultured in vitro to the third passage under the microscope to observe their morphology and growth status. The third passage of isolated cells was analysed for the identification of immunophenotype, osteogenic, adipogenic and chondrogenic differentiation. On the third to fifth days of in vitro culture, a few cells of long fusiform shape appeared and were adherent to the plastic walls. On the sixth to ninth days, cells clustered and colonies were observed. The third passage cells showed uniform cell morphology and good proliferation, with appearance of the typical surface markers of MSC, CD29, CD44, CD90 and CD105. The surface markers of CD34 and CD45 of haematopoietic stem cells were not expressed. Under appropriate conditions of in vitro culture, isolated cells could be differentiated into osteoblasts that deposit mineralised matrix and express early osteogenic markers, adipocytes that accumulate lipid droplets in cytoplasm and chondrocytes that secrete chondrogenic-specific matrix aggrecan and collagen II. Real-time polymerase chain reaction (PCR) analysis demonstrated that the specific mRNA expression of osteogenesis, adipogenesis and chondrogenesis increased significantly compared with the control groups at day zero. Stem cells derived in situ from the human ACL stump were successfully isolated and characterised. Those isolated cells were identified as MSC according to their adherent ability, morphology, surface markers and multilineage differentiation potential. MSC derived from ACL remnants could be a potential source of seeding cells for ligament regeneration.

Sumatra-Andaman Megathrust Earthquake Slip: Insights From Mechanical Modeling of ICESat Surface Deformation Measurements

NASA Astrophysics Data System (ADS)

Harding, D. J.; Miuller, J. R.

2005-12-01

Modeling the kinematics of the 2004 Great Sumatra-Andaman earthquake is limited in the northern two-thirds of the rupture zone by a scarcity of near-rupture geodetic deformation measurements. Precisely repeated Ice, Cloud, and Land Elevation Satellite (ICESat) profiles across the Andaman and Nicobar Islands provide a means to more fully document the spatial pattern of surface vertical displacements and thus better constrain geomechanical modeling of the slip distribution. ICESat profiles that total ~45 km in length cross Car Nicobar, Kamorta, and Katchall in the Nicobar chain. Within the Andamans, the coverage includes ~350 km on North, Central, and South Andaman Islands along two NNE and NNW-trending profiles that provide elevations on both the east and west coasts of the island chain. Two profiles totaling ~80 km in length cross South Sentinel Island, and one profile ~10 km long crosses North Sentinel Island. With an average laser footprint spacing of 175 m, the total coverage provides over 2700 georeferenced surface elevations measurements for each operations period. Laser backscatter waveforms recorded for each footprint enable detection of forest canopy top and underlying ground elevations with decimeter vertical precision. Surface elevation change is determined from elevation profiles, acquired before and after the earthquake, that are repeated with a cross-track separation of less than 100 m by precision pointing of the ICESat spacecraft. Apparent elevation changes associated with cross-track offsets are corrected according to local slopes calculated from multiple post-earthquake repeated profiles. The surface deformation measurements recorded by ICESat are generally consistent with the spatial distribution of uplift predicted by a preliminary slip distribution model. To predict co-seismic surface deformation, we apply a slip distribution, derived from the released energy distribution computed by Ishii et al. (2005), as the displacement discontinuity boundary condition on the Sumatra-Andaman subduction interface fault. The direction of slip on the fault surface is derived from the slip directions computed by Tsai et al. (in review) for centroid moment tensor focal mechanisms spatially distributed along the rupture. The slip model will be refined to better correspond to the observed surface deformation as additional results from the ICESat profiles become available.

[Spontaneous splenic rupture in the course of infectious mononucleosis].

PubMed

Irga, Ninela; Mierzejewska, Marta; Balcerska, Anna

2006-01-01

Spontaneous splenic rupture (SSR) in the course of infectious mononucleosis (IM) is a rare but potentially fatal complication. Mortality rate is relatively high, therefore emergency splenectomy is a life-saving intervention. In case of undergoing urgent operation there is no possibility to initiate proper prophylaxis of overwhelming infection. The humoral and cellular immunologic response impairment is a reason for life-threatening complications of splenectomised person. Asplenic children should receive infection prophylaxis immediately post splenectomy. We report two cases of splenic rupture inpatients with IM. The prevention of infection was initiated in both children. The mainstays of prophylaxis are: immunization, chemoprophylaxis and education. Complex information concerning asplenia-related subjects should be provided for patients and their parents.

Stress triggering in thrust and subduction earthquakes and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults

USGS Publications Warehouse

Lin, J.; Stein, R.S.

2004-01-01

We argue that key features of thrust earthquake triggering, inhibition, and clustering can be explained by Coulomb stress changes, which we illustrate by a suite of representative models and by detailed examples. Whereas slip on surface-cutting thrust faults drops the stress in most of the adjacent crust, slip on blind thrust faults increases the stress on some nearby zones, particularly above the source fault. Blind thrusts can thus trigger slip on secondary faults at shallow depth and typically produce broadly distributed aftershocks. Short thrust ruptures are particularly efficient at triggering earthquakes of similar size on adjacent thrust faults. We calculate that during a progressive thrust sequence in central California the 1983 Mw = 6.7 Coalinga earthquake brought the subsequent 1983 Mw = 6.0 Nunez and 1985 Mw = 6.0 Kettleman Hills ruptures 10 bars and 1 bar closer to Coulomb failure. The idealized stress change calculations also reconcile the distribution of seismicity accompanying large subduction events, in agreement with findings of prior investigations. Subduction zone ruptures are calculated to promote normal faulting events in the outer rise and to promote thrust-faulting events on the periphery of the seismic rupture and its downdip extension. These features are evident in aftershocks of the 1957 Mw = 9.1 Aleutian and other large subduction earthquakes. We further examine stress changes on the rupture surface imparted by the 1960 Mw = 9.5 and 1995 Mw = 8.1 Chile earthquakes, for which detailed slip models are available. Calculated Coulomb stress increases of 2-20 bars correspond closely to sites of aftershocks and postseismic slip, whereas aftershocks are absent where the stress drops by more than 10 bars. We also argue that slip on major strike-slip systems modulates the stress acting on nearby thrust and strike-slip faults. We calculate that the 1857 Mw = 7.9 Fort Tejon earthquake on the San Andreas fault and subsequent interseismic slip brought the Coalinga fault ???1 bar closer to failure but inhibited failure elsewhere on the Coast Ranges thrust faults. The 1857 earthquake also promoted failure on the White Wolf reverse fault by 8 bars, which ruptured in the 1952 Mw = 7.3 Kern County shock but inhibited slip on the left-lateral Garlock fault, which has not ruptured since 1857. We thus contend that stress transfer exerts a control on the seismicity of thrust faults across a broad spectrum of spatial and temporal scales. Copyright 2004 by the American Geophysical Union.