Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake

NASA Astrophysics Data System (ADS)

Koketsu, Kazuki; Miyake, Hiroe; Guo, Yujia; Kobayashi, Hiroaki; Masuda, Tetsu; Davuluri, Srinagesh; Bhattarai, Mukunda; Adhikari, Lok Bijaya; Sapkota, Soma Nath

2016-06-01

The ground motion and damage caused by the 2015 Gorkha, Nepal earthquake can be characterized by their widespread distributions to the east. Evidence from strong ground motions, regional acceleration duration, and teleseismic waveforms indicate that rupture directivity contributed significantly to these distributions. This phenomenon has been thought to occur only if a strike-slip or dip-slip rupture propagates to a site in the along-strike or updip direction, respectively. However, even though the earthquake was a dip-slip faulting event and its source fault strike was nearly eastward, evidence for rupture directivity is found in the eastward direction. Here, we explore the reasons for this apparent inconsistency by performing a joint source inversion of seismic and geodetic datasets, and conducting ground motion simulations. The results indicate that the earthquake occurred on the underthrusting Indian lithosphere, with a low dip angle, and that the fault rupture propagated in the along-strike direction at a velocity just slightly below the S-wave velocity. This low dip angle and fast rupture velocity produced rupture directivity in the along-strike direction, which caused widespread ground motion distribution and significant damage extending far eastwards, from central Nepal to Mount Everest.

Implementing the effect of the rupture directivity on PSHA maps: Application to the Marmara Region (Turkey)

NASA Astrophysics Data System (ADS)

Herrero, Andre; Spagnuolo, Elena; Akinci, Aybige; Pucci, Stefano

2016-04-01

In the present study we attempted to improve the seismic hazard assessment taking into account possible sources of epistemic uncertainty and the azimuthal variability of the ground motions which, at a particular site, is significantly influenced by the rupture mechanism and the rupture direction relative to the site. As a study area we selected Marmara Region (Turkey), especially the city of Istanbul which is characterized by one of the highest levels of seismic risk in Europe and the Mediterranean region. The seismic hazard in the city is mainly associated with two active fault segments which are located at about 20-30 km south of Istanbul. In this perspective first we proposed a methodology to incorporate this new information such as nucleation point in a probabilistic seismic hazard analysis (PSHA) framework. Secondly we introduced information about those fault segments by focusing on the fault rupture characteristics which affect the azimuthal variations of the ground motion spatial distribution i.e. source directivity effect and its influence on the probabilistic seismic hazard analyses (PSHA). An analytical model developed by Spudich and Chiou (2008) is used as a corrective factor that modifies the Next Generation Attenuation (NGA, Power et al. 2008) ground motion predictive equations (GMPEs) introducing rupture related parameters that generally lump together into the term directivity effect. We used the GMPEs as derived by the Abrahamson and Silva (2008) and the Boore and Atkinson (2008); our results are given in terms of 10% probability of exceedance of PSHA (at several periods from 0.5 s to 10 s) in 50 years on rock site condition; the correction for directivity introduces a significant contribution to the percentage ratio between the seismic hazards computed using the directivity model respect to the seismic hazard standard practice. In particular, we benefited the dynamic simulation from a previous study (Aochi & Utrich, 2015) aimed at evaluating the seismic potential of the Marmara region to derive a statistical distribution for nucleation position. Our results suggest that accounting for rupture related parameters in a PSHA using deterministic information from dynamic models is feasible and in particular, the use of a non-uniform statistical distribution for nucleation position has serious consequences on the hazard assessment. Since the directivity effect is conditional on the nucleation position the hazard map changes with the assumptions made. A worst case scenario (both the faults are rupturing towards the city of Istanbul) predicts up to 25% change than the standard formulation at 2 sec and increases with longer periods. The former result is heavily different if a deterministically based nucleation position is assumed.

Comparison of NGA-West2 directivity models

USGS Publications Warehouse

Spudich, Paul A.; Rowshandel, Badie; Shahi, Shrey; Baker, Jack W.; Chiou, Brian S-J

2014-01-01

Five directivity models have been developed based on data from the NGA-West2 database and based on numerical simulations of large strike-slip and reverse-slip earthquakes. All models avoid the use of normalized rupture dimension, enabling them to scale up to the largest earthquakes in a physically reasonable way. Four of the five models are explicitly “narrow-band” (in which the effect of directivity is maximum at a specific period that is a function of earthquake magnitude). Several strategies for determining the zero-level for directivity have been developed. We show comparisons of maps of the directivity amplification. This comparison suggests that the predicted geographic distributions of directivity amplification are dominated by effects of the models' assumptions, and more than one model should be used for ruptures dipping less than about 65 degrees.

The effect of thermal cycling on the structure and properties of a Co, Cr, Ni-TaC directionally solidified eutectic composite

NASA Technical Reports Server (NTRS)

Dunlevey, F. M.; Wallace, J. F.

1973-01-01

The effect of thermal cycling on the structure and properties of a cobalt, chromium, nickel, tantalum carbide directionally solidified eutectic composite is reported. It was determined that the stress rupture properties of the alloy were decreased by the thermal cycling. The loss in stress rupture properties varied with the number of cycles with the loss in properties after about 200 cycles being relatively high. The formation of serrations and the resulting changes in the mechanical properties of the material are discussed.

Observing earthquakes triggered in the near field by dynamic deformations

USGS Publications Warehouse

Gomberg, J.; Bodin, P.; Reasenberg, P.A.

2003-01-01

We examine the hypothesis that dynamic deformations associated with seismic waves trigger earthquakes in many tectonic environments. Our analysis focuses on seismicity at close range (within the aftershock zone), complementing published studies of long-range triggering. Our results suggest that dynamic triggering is not confined to remote distances or to geothermal and volcanic regions. Long unilaterally propagating ruptures may focus radiated dynamic deformations in the propagation direction. Therefore, we expect seismicity triggered dynamically by a directive rupture to occur asymmetrically, with a majority of triggered earthquakes in the direction of rupture propagation. Bilaterally propagating ruptures also may be directive, and we propose simple criteria for assessing their directivity. We compare the inferred rupture direction and observed seismicity rate change following 15 earthquakes (M 5.7 to M 8.1) that occured in California and Idaho in the United States, the Gulf of Aqaba, Syria, Guatemala, China, New Guinea, Turkey, Japan, Mexico, and Antarctica. Nine of these mainshocks had clearly directive, unilateral ruptures. Of these nine, seven apparently induced an asymmetric increase in seismicity rate that correlates with the rupture direction. The two exceptions include an earthquake preceded by a comparable-magnitude event on a conjugate fault and another for which data limitations prohibited conclusive results. Similar (but weaker) correlations were found for the bilaterally rupturing earthquakes we studied. Although the static stress change also may trigger seismicity, it and the seismicity it triggers are expected to be similarly asymmetric only if the final slip is skewed toward the rupture terminus. For several of the directive earthquakes, we suggest that the seismicity rate change correlates better with the dynamic stress field than the static stress change.

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.

Material contrast does not predict earthquake rupture propagation direction

USGS Publications Warehouse

Harris, R.A.; Day, S.M.

2005-01-01

Earthquakes often occur on faults that juxtapose different rocks. The result is rupture behavior that differs from that of an earthquake occurring on a fault in a homogeneous material. Previous 2D numerical simulations have studied simple cases of earthquake rupture propagation where there is a material contrast across a fault and have come to two different conclusions: 1) earthquake rupture propagation direction can be predicted from the material contrast, and 2) earthquake rupture propagation direction cannot be predicted from the material contrast. In this paper we provide observational evidence from 70 years of earthquakes at Parkfield, CA, and new 3D numerical simulations. Both the observations and the numerical simulations demonstrate that earthquake rupture propagation direction is unlikely to be predictable on the basis of a material contrast. Copyright 2005 by the American Geophysical Union.

CyberShake: A Physics-Based Seismic Hazard Model for Southern California

NASA Astrophysics Data System (ADS)

Graves, Robert; Jordan, Thomas H.; Callaghan, Scott; Deelman, Ewa; Field, Edward; Juve, Gideon; Kesselman, Carl; Maechling, Philip; Mehta, Gaurang; Milner, Kevin; Okaya, David; Small, Patrick; Vahi, Karan

2011-03-01

CyberShake, as part of the Southern California Earthquake Center's (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200 km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i.e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2 s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process.

CyberShake: A Physics-Based Seismic Hazard Model for Southern California

USGS Publications Warehouse

Graves, R.; Jordan, T.H.; Callaghan, S.; Deelman, E.; Field, E.; Juve, G.; Kesselman, C.; Maechling, P.; Mehta, G.; Milner, K.; Okaya, D.; Small, P.; Vahi, K.

2011-01-01

CyberShake, as part of the Southern California Earthquake Center's (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200 km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i. e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2 s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process. ?? 2010 Springer Basel AG.

The evolution of slip pulses within bimaterial interfaces with rupture velocity

NASA Astrophysics Data System (ADS)

Shlomai, H.; Fineberg, J.

2017-12-01

The most general frictional motion in nature involves bimaterial interfaces, when contacting bodies possess different elastic properties. Frictional motion occurs when the contacts composing the interface separating these bodies detach via propagating rupture fronts. Coupling between slip and normal stress variations is unique to bimaterial interfaces. Here we use high speed simultaneous measurements of slip velocities, real contact area and stresses to explicitly reveal this bimaterial coupling and its role in determining different classes of rupture modes and their structures. Our experiments study the rupture of a spatially extended interface formed by brittle plastics whose shear wave speeds differ by 30%. Any slip within a bimaterial interface will break the stress symmetry across the interface. One important result of this is that local values of normal stress variations at the interface couple to interface slip, `bimaterial coupling'. The sign of the coupling depends on the front propagation direction. When we consider ruptures propagating in the direction of motion of the more compliant material, the `positive' direction, slip reduces the normal stress. We focus on this direction. We show that, in this direction, interface ruptures develop from crack-like behavior at low rupture velocities, whose structure corresponds to theoretical predictions: As the ruptures accelerate towards their asymptotic speed, the structures of the strain and stress fields near the rupture tip deviate significantly from this crack-like form, and systematically sharpen to a pulse-like rupture mode called slip-pulses. We conclude with a description of slip-pulse properties.

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.

Slip complexity and frictional heterogeneities in dynamic fault models

NASA Astrophysics Data System (ADS)

Bizzarri, A.

2005-12-01

The numerical modeling of earthquake rupture requires the specification of the fault system geometry, the mechanical properties of the media surrounding the fault, the initial conditions and the constitutive law for fault friction. The latter accounts for the fault zone properties and allows for the description of processes of nucleation, propagation, healing and arrest of a spontaneous rupture. In this work I solve the fundamental elasto-dynamic equation for a planar fault, adopting different constitutive equations (slip-dependent and rate- and state-dependent friction laws). We show that the slip patterns may be complicated by different causes. The spatial heterogeneities of constitutive parameters are able to cause the healing of slip, like barrier-healing or slip pulses. Our numerical experiments show that the heterogeneities of the parameter L affect the dynamic rupture propagation and weakly modify the dynamic stress drop and the rupture velocity. The heterogeneity of a and b parameters affects the dynamic rupture propagation in a more complex way: a velocity strengthening area (a > b) can arrest a dynamic rupture, but can be driven to an instability if suddenly loaded by the dynamic rupture front. Our simulations provide a picture of the complex interactions between fault patches having different frictional properties. Moreover, the slip distribution on the fault plane is complicated considering the effects of the rake rotation during the propagation: depending on the position on the fault plane, the orientation of instantaneous total dynamic traction can change with time with respect to the imposed initial stress direction. These temporal rake rotations depend on the amplitude of the initial stress and on its distribution. They also depend on the curvature and direction of the rupture front with respect to the imposed initial stress direction: this explains why rake rotations are mostly located near the rupture front and within the cohesive zone, where the breakdown processes take places. Finally, the rupture behavior, the fault slip distribution and the traction evolution may be changed and complicated including additional physical phenomena, like thermal pressurization of pore fluid (due to frictional heating). Our results involve interesting implications for slip duration and fracture energy.

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

Aagaard, B T; Graves, R W; Rodgers, A

We simulate long-period (T > 1.0-2.0 s) and broadband (T > 0.1 s) ground motions for 39 scenarios earthquakes (Mw 6.7-7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area with about 50% of the urban area experiencing MMI VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18more » Oakland and 2007 Mw 4.5 Alum Rock earthquakes show that the USGS Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the Next Generation Attenuation (NGA) ground-motion prediction equations. We attribute at least some of this difference to the relatively narrow width of the Hayward fault ruptures. The simulations suggest that the Spudich and Chiou (2008) directivity corrections to the NGA relations could be improved by including a dependence on the rupture speed and increasing the areal extent of rupture directivity with period. The simulations also indicate that the NGA relations may under-predict amplification in shallow sedimentary basins.« less

Source parameters controlling the generation and propagation of potential local tsunamis along the cascadia margin

USGS Publications Warehouse

Geist, E.; Yoshioka, S.

1996-01-01

The largest uncertainty in assessing hazards from local tsunamis along the Cascadia margin is estimating the possible earthquake source parameters. We investigate which source parameters exert the largest influence on tsunami generation and determine how each parameter affects the amplitude of the local tsunami. The following source parameters were analyzed: (1) type of faulting characteristic of the Cascadia subduction zone, (2) amount of slip during rupture, (3) slip orientation, (4) duration of rupture, (5) physical properties of the accretionary wedge, and (6) influence of secondary faulting. The effect of each of these source parameters on the quasi-static displacement of the ocean floor is determined by using elastic three-dimensional, finite-element models. The propagation of the resulting tsunami is modeled both near the coastline using the two-dimensional (x-t) Peregrine equations that includes the effects of dispersion and near the source using the three-dimensional (x-y-t) linear long-wave equations. The source parameters that have the largest influence on local tsunami excitation are the shallowness of rupture and the amount of slip. In addition, the orientation of slip has a large effect on the directivity of the tsunami, especially for shallow dipping faults, which consequently has a direct influence on the length of coastline inundated by the tsunami. Duration of rupture, physical properties of the accretionary wedge, and secondary faulting all affect the excitation of tsunamis but to a lesser extent than the shallowness of rupture and the amount and orientation of slip. Assessment of the severity of the local tsunami hazard should take into account that relatively large tsunamis can be generated from anomalous 'tsunami earthquakes' that rupture within the accretionary wedge in comparison to interplate thrust earthquakes of similar magnitude. ?? 1996 Kluwer Academic Publishers.

Forecasting the Rupture Directivity of Large Earthquakes: Centroid Bias of the Conditional Hypocenter Distribution

NASA Astrophysics Data System (ADS)

Donovan, J.; Jordan, T. H.

2012-12-01

Forecasting the rupture directivity of large earthquakes is an important problem in probabilistic seismic hazard analysis (PSHA), because directivity is known to strongly influence ground motions. We describe how rupture directivity can be forecast in terms of the "conditional hypocenter distribution" or CHD, defined to be the probability distribution of a hypocenter given the spatial distribution of moment release (fault slip). The simplest CHD is a uniform distribution, in which the hypocenter probability density equals the moment-release probability density. For rupture models in which the rupture velocity and rise time depend only on the local slip, the CHD completely specifies the distribution of the directivity parameter D, defined in terms of the degree-two polynomial moments of the source space-time function. This parameter, which is zero for a bilateral rupture and unity for a unilateral rupture, can be estimated from finite-source models or by the direct inversion of seismograms (McGuire et al., 2002). We compile D-values from published studies of 65 large earthquakes and show that these data are statistically inconsistent with the uniform CHD advocated by McGuire et al. (2002). Instead, the data indicate a "centroid biased" CHD, in which the expected distance between the hypocenter and the hypocentroid is less than that of a uniform CHD. In other words, the observed directivities appear to be closer to bilateral than predicted by this simple model. We discuss the implications of these results for rupture dynamics and fault-zone heterogeneities. We also explore their PSHA implications by modifying the CyberShake simulation-based hazard model for the Los Angeles region, which assumed a uniform CHD (Graves et al., 2011).

Macroscopic Asymmetry of Dynamic Rupture on a Bimaterial Interface With Velocity- Weakening Friction

NASA Astrophysics Data System (ADS)

Ampuero, J.; Ben-Zion, Y.

2006-12-01

Large faults typically separate rocks of different elastic properties. In-plane ruptures on bimaterial interfaces have remarkable dynamic properties that may be relevant to many issues of basic and applied science (e.g., Ben-Zion, 2001). In contrast to slip between similar media, slip along a bimaterial interface generates dynamic changes of normal stress that modify the local fault strength (e.g., Weertman, 1980). One important issue is whether rupture on a bimaterial interface evolves toward a unilateral wrinkle-like pulse in the direction of motion of the compliant medium (the "preferred" direction), or whether it propagates as a symmetric bilateral crack. Some field data suggest that bimaterial interfaces in natural fault zones produce macroscopic rupture asymmetry (Dor et al., 2006; Lewis et al., 2005, 2006); however, this is a subject of ongoing debate. Rubin and Ampuero (2006) performed numerical simulations of bimaterial ruptures under pure slip-weakening friction. They found bilateral crack-like ruptures without significant asymmetry of slip. For ruptures that stopped in low stress areas, there was asymmetry in the final stress distribution, induced by a small scale pulse that detaches from the crack when it stops. This may provide a mechanism for the observed asymmetry of microearthquakes on segments of the San Andreas fault (Rubin and Gillard, 2000). In addition, the results included very prominent asymmetry of slip velocities at the opposite rupture fronts. In calculations with slip-weakening friction the strong asymmetry of slip velocities can not manifest itself into macroscopic rupture asymmetry. However, incorporating in the simulations rate-dependent friction may produce larger stress drop in the preferred direction, leading to macroscopically asymmetric rupture (Ben-Zion, 2006). In this work we study the effect of velocity-weakening friction on rupture along a bimaterial interface, using 2D in-plane simulations with a spectral boundary integral method and a rate-and-state dependent friction law with strong velocity dependence. The law contains slip-weakening or velocity-weakening as limit cases, depending on the length scale in the state evolution law. The steady-state friction coefficient is inversely proportional to slip-rate, mimicking the weakening mechanisms thought to operate on natural faults at high velocities. We examine the behavior of ruptures triggered by a slightly overstressed nucleation zone of size larger than a critical size derived by linear stability analysis. We characterize the range of friction parameters and initial stress values for which ruptures behave as cracks or pulses, decaying or sustained, with subshear or super-shear speeds. All sustained ruptures are initially bilateral. In the range where sub-shear pulse-like rupture is observed, the ruptures develop strong macroscopic asymmetry with continuing propagation along the bimaterial interface. This is manifested by significantly larger seismic potency and propagation distance in the preferred direction, similar to what was found by Shi and Ben-Zion (2006) with strong nucleation phases and slip-weakening friction. The stress asymmetry mechanism described by Rubin and Ampuero (2006) remains in our velocity-weakening simulations as a super-imposed small-scale feature.

Investigating the rupture direction of induced earthquakes in the Central US using empirical Green's functions

NASA Astrophysics Data System (ADS)

Lui, S. K. Y.; Huang, Y.

2017-12-01

A clear understanding of the source physics of induced seismicity is the key to effective seismic hazard mitigation. In particular, resolving their rupture processes can shed lights on the stress state prior to the main shock, as well as ground motion response. Recent numerical models suggest that, compared to their tectonic counterpart, induced earthquake rupture is more prone to propagate unilaterally toward the injection well where fluid pressure is high. However, this is also dependent on the location of the injection relative to the fault and yet to be compared with field data. In this study, we utilize the rich pool of seismic data in the central US to constrain the rupture processes of major induced earthquakes. By implementing a forward-modeling method, we take smaller earthquake recordings as empirical Green's functions (eGf) to simulate the rupture direction of the beginning motion generated by large events. One advantage of the empirical approach is to bypass the fundamental difficulty in resolving path and site effects. We selected eGf events that are close to the target events both in space and time. For example, we use a Mw 3.6 aftershock approximately 3 km from the 2011 Mw 5.7 earthquake in Prague, OK as its eGf event. Preliminary results indicate a southwest rupture for the Prague main shock, which possibly implies a higher fluid pressure concentration on the northeast end of the fault prior to the rupture. We will present further results on other Mw > 4.5 earthquakes in the States of Oklahoma and Kansas. With additional seismic stations installed in the past few years, events such as the 2014 Mw 4.9 Milan earthquake and the 2016 Mw 5.8 Pawnee earthquake are potential candidates with useful eGfs, as they both have good data coverage and a substantial number of aftershocks nearby. We will discuss the implication of our findings for the causative relationships between the injection operations and the induced rupture process.

A Combined Experimental and Numerical Modeling Study of the Deformation and Rupture of Axisymmetric Liquid Bridges under Coaxial Stretching.

PubMed

Zhuang, Jinda; Ju, Y Sungtaek

2015-09-22

The deformation and rupture of axisymmetric liquid bridges being stretched between two fully wetted coaxial disks are studied experimentally and theoretically. We numerically solve the time-dependent Navier-Stokes equations while tracking the deformation of the liquid-air interface using the arbitrary Lagrangian-Eulerian (ALE) moving mesh method to fully account for the effects of inertia and viscous forces on bridge dynamics. The effects of the stretching velocity, liquid properties, and liquid volume on the dynamics of liquid bridges are systematically investigated to provide direct experimental validation of our numerical model for stretching velocities as high as 3 m/s. The Ohnesorge number (Oh) of liquid bridges is a primary factor governing the dynamics of liquid bridge rupture, especially the dependence of the rupture distance on the stretching velocity. The rupture distance generally increases with the stretching velocity, far in excess of the static stability limit. For bridges with low Ohnesorge numbers, however, the rupture distance stay nearly constant or decreases with the stretching velocity within certain velocity windows due to the relative rupture position switching and the thread shape change. Our work provides an experimentally validated modeling approach and experimental data to help establish foundation for systematic further studies and applications of liquid bridges.

Transverse tensile and stress rupture properties of gamma/gamma prime-delta directionally solidified eutectic

NASA Technical Reports Server (NTRS)

Gray, H. H.

1976-01-01

Tensile and stress rupture properties were determined primarily at 760 C for specimens oriented at various angles (0 deg, 10 deg, 45 deg, and 90 deg) from the solidification direction of bars and/or slabs of the Ni-20Cb-6Cr-2.5A (gamma/gamma prime-delta) eutectic. Threaded-head specimens yielded longer rupture lives with significantly less scatter than did tapered-head specimens. Miniature specimens are suitable for determining traverse tensile and rupture properties of 1.2 centimeter diameter bar stock. The 300 hour rupture stress at 760 C for specimens oriented at 10 deg from the solidification direction was reduced from 740 to 460 MPa, and to 230 MPa for material oriented at either 45 deg or 90 deg.

Microstructural changes caused by thermal treatment and their effects on mechanical properties of a gamma/gamma prime - delta eutectic alloy

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Dreshfield, R. L.

1976-01-01

Microstructural changes due to thermal treatments of a directionally solidified gamma/gamma'-delta eutectic alloy were investigated. Aging treatments of 8 to 48 hours and ranging from 750 to 1120 C were given to the alloy in both its as directionally solidified condition and after gamma' solutioning. Aging resulted in gamma' coarsening gamma precipitates in delta, and delta and gamma'' precipitates in delta. The tensile strength was increased about 12 percent at temperatures up to 900 C by a heat treatment. Times to rupture were essentially the same or greater than for as directionally solidified material. Tensile and rupture ductility in the growth direction of the alloy were reduced by the heat treatment.

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.

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

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).

Examining Structural Controls on Earthquake Rupture Dynamics Along the San Andreas Fault

NASA Astrophysics Data System (ADS)

McGuire, J. J.; Ben-Zion, Y.

2002-12-01

Recent numerical simulations of dynamic rupture [Andrews and Ben-Zion, 1997; Harris and Day, 1997] have confirmed earlier analytical results [Weertman, 1980; Adams, 1995] that a contrast in elastic properties between the two sides of a fault will generate an interaction between the normal stress and fault slip that is not present in a homogeneous medium. It has been shown that for a range of frictional parameters and initial conditions, this interaction produces a statistical preference for unilateral rupture propagation in the direction of slip of the more compliant medium [Ben-Zion and Andrews, 1998; Cochard and Rice, 2000; Ben-Zion and Huang 2002]. Thus, the directivity of earthquake ruptures on large faults with well-developed material interfaces may be controlled by material contrasts of the rocks within and across the fault zone. One of the largest known velocity contrasts across a major crustal fault occurs along the Bear Valley section of the San Andreas where high velocity materials on the SW side (P-velocity >5 km/s) are juxtaposed with low-velocity material on the NE side (P-velocity <4 km/s) down to a depth of about 4 km with a less dramatic contrast continuing to about 8 km [Thurber et al., 1997]. This boundary is strong enough to generate significant head-waves refracted along it that are recorded as the first arrivals at stations close to the fault on the NE side [McNally and McEvilly, 1977]. Rubin and Gillard [2000] and Rubin [2002] relocated the events in this region using NCSN waveform data and found that more than twice as many immediate aftershocks to small earthquakes occurred to the NW of the mainshock as to the SE, which they interpreted as being consistent with a preferred rupture direction to the SE. Their interpretation that aftershocks to microearthquakes occur preferentially in the direction opposite of rupture propagation has not been directly tested and is inconsistent with observations from moderate [Fletcher and Spudich, 1998] and large earthquakes [Kilb et al., 2000], which show considerable variability and possibly the opposite preference. We are attempting to directly test the prediction of a preference for rupture propagation to the SE on this fault segment by combining travel-time and waveform modeling of fault-zone head waves, high precision earthquake relocations, and rupture directivity studies. Initial results indicate that there is considerable variability along strike in the strength of the across-fault velocity contrast, with maximum values reaching about 25-30%. This spatial variability in the strength of the material property contrast would be expected to produce a spatial variability in earthquake rupture directivity. We are developing a catalog of earthquake rupture directivity estimates for magnitude 2 and larger earthquakes to compare with the variations of the velocity contrast and aftershock asymmetry. Initial results indicate that even in the regions of highest velocity contrast, moderate earthquakes (M=3) can still rupture unilaterally to the NE. Detailed high resolution results from head-wave modeling, rupture directivity studies, and earthquake relocations will be presented.

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.

Application of Computed Tomography Processed by Picture Archiving and Communication Systems in the Diagnosis of Acute Achilles Tendon Rupture

PubMed Central

Tian, Jing; Xie, Bing; Zhang, Hao

2016-01-01

The applications of CT examination in the diagnosis of the acute Achilles tendon rupture (AATR) were investigated. A total of 36 patients with suspected acute Achilles tendon rupture were tested using physical examination, ultrasound, and 3DCT scanning, respectively. Then, surgery was performed for the patients who showed positive result in at least two of the three tests for AATR. 3DVR, MPR, and the other CT scan image processing and diagnosis were conducted in PACS (picture archiving and communication system). PACS was also used to measure the length of distal broken ends of the Achilles tendon (AT) to tendon calcaneal insertion. Our study indicated that CT has the highest accuracy in diagnosis of acute Achilles tendon complete rupture. The length measurement is matched between PACS and those actually measured in operation. CT not only demonstrates more details directly in three dimensions especially with the rupture involved calcaneal insertion flap but also locates the rupture region for percutaneous suture by measuring the length of distal stump in PACS without the effect of the position of ankle. The accuracy of CT diagnosis for Achilles tendon partial rupture is yet to be studied. PMID:28078295

[Successful correction with stent-graft of coronary artery rupture after angioplasty].

PubMed

Demin, V V

2003-01-01

Rupture and perforation of coronary arteries complicate in average 0.5% of radiosurgical coronary interventions and often are accompanied by serious consequences and high mortality. According to-type of coronary perforation different methods of correction are used, ranging from conservative measures to urgent cardiosurgical interventions. Coronary stent-grafts with 'sandwich' type of construction ore composed from two metal stents and PTFE layer between them. Development of such stents enabled effective radioguided endovascular repair of coronary ruptures. The paper presents the first Russian experience of stout-graft implantation for coronary artery rupture occurred during direct stenting of proximal anterior descending artery and balloon angioplasty in distal segment. The rupture occurred probably because of wall fragility between affected segment and muscular bridge. Stent-graft JoStent 16 mm in length connected with 3-mm balloon was implanted with subsequent complete restitution of blood flow, resolution of pain syndrome and ECG normalization. Echocardiography in operative theatre and one day after surgery showed no intrapericardial fluid. Stent-graft devices for urgent implantation in cases of coronary rupture must be included into obligatory equipment of radiosurgical facilities.

Rupture directivity and slip distribution of the M 4.3 foreshock to the 1992 Joshua Tree earthquake, Southern California

USGS Publications Warehouse

Mori, J.

1996-01-01

Details of the M 4.3 foreshock to the Joshua Tree earthquake were studied using P waves recorded on the Southern California Seismic Network and the Anza network. Deconvolution, using an M 2.4 event as an empirical Green's function, corrected for complicated path and site effects in the seismograms and produced simple far-field displacement pulses that were inverted for a slip distribution. Both possible fault planes, north-south and east-west, for the focal mechanism were tested by a least-squares inversion procedure with a range of rupture velocities. The results showed that the foreshock ruptured the north-south plane, similar to the mainshock. The foreshock initiated a few hundred meters south of the mainshock and ruptured to the north, toward the mainshock hypocenter. The mainshock (M 6.1) initiated near the northern edge of the foreshock rupture 2 hr later. The foreshock had a high stress drop (320 to 800 bars) and broke a small portion of the fault adjacent to the mainshock but was not able to immediately initiate the mainshock rupture.

Isolated abducens nerve palsy associated with subarachnoid hemorrhage: a localizing sign of ruptured posterior inferior cerebellar artery aneurysms.

PubMed

Burkhardt, Jan-Karl; Winkler, Ethan A; Lasker, George F; Yue, John K; Lawton, Michael T

2018-06-01

OBJECTIVE Compressive cranial nerve syndromes can be useful bedside clues to the diagnosis of an enlarging intracranial aneurysm and can also guide subsequent evaluation, as with an acute oculomotor nerve (cranial nerve [CN] III) palsy that is presumed to be a posterior communicating artery aneurysm and a surgical emergency until proven otherwise. The CN VI has a short cisternal segment from the pontomedullary sulcus to Dorello's canal, remote from most PICA aneurysms but in the hemodynamic pathway of a rupturing PICA aneurysm that projects toward Dorello's canal. The authors describe a cranial nerve syndrome for posterior inferior cerebellar artery (PICA) aneurysms that associates subarachnoid hemorrhage (SAH) and an isolated abducens nerve (CN VI) palsy. METHODS Clinical and radiological data from 106 surgical patients with PICA aneurysms (66 ruptured and 40 unruptured) were retrospectively reviewed. Data from a group of 174 patients with other aneurysmal SAH (aSAH) were analyzed in a similar manner to control for nonspecific effects of SAH. Univariate statistical analysis compared incidence and risk factors associated with CN VI palsy in subarachnoid hemorrhage. RESULTS Overall, 13 (4.6%) of 280 patients had CN VI palsy at presentation, and all of them had ruptured aneurysms (representing 13 [5.4%] of the 240 cases of ruptured aneurysms). CN VI palsies were observed in 12 patients with ruptured PICA aneurysms (12/66 [18.1%]) and 1 patient with other aSAH (1/174 [0.1%], p < 0.0001). PICA aneurysm location in ruptured aneurysms was an independent predictor for CN VI palsy on multivariate analysis (p = 0.001). PICA aneurysm size was not significantly different in patients with or without CN VI palsy (average size 4.4 mm and 5.2 mm, respectively). Within the PICA aneurysm cohort, modified Fisher grade (p = 0.011) and presence of a thick cisternal SAH (modified Fisher Grades 3 and 4) (p = 0.003) were predictors of CN VI palsy. In all patients with ruptured PICA aneurysms and CN VI palsy, dome projection and presumed direction of rupture were directed toward the ipsilateral and/or contralateral Dorello's canal, in agreement with laterality of the CN palsy. In patients with bilateral CN VI palsies, a medial projection with extensive subarachnoid blood was observed near bilateral canals. CONCLUSIONS This study establishes a localizing connection between an isolated CN VI palsy, SAH, and an underlying ruptured PICA aneurysm. CN VI palsy is an important clinical sign in aSAH and when present on initial clinical presentation may be assumed to be due to ruptured PICA aneurysms until proven otherwise. The deficit may be ipsilateral, contralateral, or bilateral and is determined by the direction of the aneurysm dome projection and extent of subarachnoid bleeding toward Dorello's canal, rather than by direct compression.

Rupture characteristics of the 2016 Meinong earthquake revealed by the back projection and directivity analysis of teleseismic broadband waveforms

NASA Astrophysics Data System (ADS)

Jian, Pei-Ru; Hung, Shu-Huei; Meng, Lingsen; Sun, Daoyuan

2017-04-01

The 2016 Mw 6.4 Meinong earthquake struck a previously unrecognized fault zone in midcrust beneath south Taiwan and inflicted heavy causalities in the populated Tainan City about 30 km northwest of the epicenter. Because of its relatively short rupture duration and P wave trains contaminated by large-amplitude depth phases and reverberations generated in the source region, accurate characterization of the rupture process and source properties for such a shallow strong earthquake remains challenging. Here we present a first high-resolution MUltiple SIgnal Classification back projection source image by using both P and depth-phase sP waves recorded at two large and dense arrays to understand the source behavior and consequent hazards of this peculiar catastrophic event. The results further corroborated by the directivity analysis indicate a unilateral rupture propagating northwestward and slightly downward on the shallow NE-dipping fault plane. The source radiation process is primarily characterized by one single peak, 7 s duration, with a total rupture length of 17 km and average rupture speed of 2.4 km/s. The rupture terminated immediately east of the prominent off-fault aftershock cluster about 20 km northwest of the hypocenter. Synergistic amplification of ground shaking by the directivity and strong excitation of sP and reverberations mainly caused the destruction concentrated in the area further to the northwest away from the rupture zone.

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.

Turbulent breakage of ductile aggregates.

PubMed

Marchioli, Cristian; Soldati, Alfredo

2015-05-01

In this paper we study breakage rate statistics of small colloidal aggregates in nonhomogeneous anisotropic turbulence. We use pseudospectral direct numerical simulation of turbulent channel flow and Lagrangian tracking to follow the motion of the aggregates, modeled as sub-Kolmogorov massless particles. We focus specifically on the effects produced by ductile rupture: This rupture is initially activated when fluctuating hydrodynamic stresses exceed a critical value, σ>σ(cr), and is brought to completion when the energy absorbed by the aggregate meets the critical breakage value. We show that ductile rupture breakage rates are significantly reduced with respect to the case of instantaneous brittle rupture (i.e., breakage occurs as soon as σ>σ(cr)). These discrepancies are due to the different energy values at play as well as to the statistical features of energy distribution in the anisotropic turbulence case examined.

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.

Vacation appendicitis.

PubMed

Redan, Jay A; Tempel, Michael B; Harrison, Shannon; Zhu, Xiang

2013-01-01

When someone plans a vacation, one of the last things taken into consideration is the possibility of contracting an illness while away. Unfortunately, if people develop abdominal pain while planning for a vacation, they usually proceed with the vacation and do not consider getting medical attention for their pain. The purpose of this study was to examine the effect of being on vacation and its association with ruptured appendicitis. From January 1, 2007 to December 31, 2008, the incidence of ruptured appendicitis cases at Florida Hospital-Celebration Health, located 5 miles from Walt Disney World, was compared with that of Florida Hospital-Orlando, approximately 30 miles away from Walt Disney World. We evaluated whether patients "on vacation" versus residents of Orlando have an increased incidence of ruptured appendicitis. Of patients treated for presumed appendicitis, 60.59% at Florida Hospital-Celebration Health had ruptured appendicitis during this time versus 20.42% at Florida Hospital-Orlando. Of those 266 patients seen at Florida Hospital-Celebration Health, 155 were on vacation versus only 21 at Florida Hospital-Orlando. Although there is not a direct cause and effect, it is clear that there is a higher incidence of ruptured appendicitis in patients on vacation versus in the regular community in the Orlando, Florida area.

Aftershock seismicity and Tectonic Setting of the 16 September 2015 Mw 8.3 Illapel earthquake

NASA Astrophysics Data System (ADS)

Lange, Dietrich; Geersen, Jacob; Barrientos, Sergio; Moreno, Marcos; Grevemeyer, Ingo; Contreras-Reyes, Eduardo; Kopp, Heidrun

2016-04-01

Powerful subduction zone earthquakes rupture thousands of square kilometers along continental margins but at certain locations earthquake rupture terminates. On 16 September 2015 the Mw. 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here we analyze the spatial pattern of coseismic rupture and the temporal and spatial pattern of local seismicity for aftershocks and foreshocks in relation to the tectonic setting in the earthquake area. Aftershock seismicity surrounds the rupture area in lateral and downdip direction. For the first 24 hours following the mainshock we observe aftershock migration to both lateral directions with velocities of approximately 2.5 and 5 km/h. At the southern earthquake boundary aftershocks cluster around individual subducted seamounts located on the prolongation of the downthrusting Juan Fernández Ridge indicating stress transfer from the main rupture area. In the northern part of the rupture area a deeper band of local seismicity is observed indicating an alternation of seismic to aseismic behavior of the plate interface in downdip direction. This aseismic region at ~30 km depth that is also observed before the Illapel 2015 earthquake is likely controlled by the intersection of the continental Moho with the subducting slab.

A formulation of directivity for earthquake sources using isochrone theory

USGS Publications Warehouse

Spudich, Paul; Chiou, Brian S.J.; Graves, Robert; Collins, Nancy; Somerville, Paul

2004-01-01

A functional form for directivity effects can be derived from isochrone theory, in which the measure of the directivity-induced amplification of an S body wave is c, the isochrone velocity. Ground displacement of the near-, intermediate-, and far-field terms of P and S waves is linear in isochrone velocity for a finite source in a whole space. We have developed an approximation c-tilde-prime of isochrone velocity that can easily be implemented as a predictor of directivity effects in empirical ground motion prediction relations. Typically, for a given fault surface, hypocenter, and site geometry, c-tilde-prime is a simple function of the hypocentral distance, the rupture distance, the crustal shear wave speed in the seismogenic zone, and the rupture velocity. c-tilde-prime typically ranges in the interval 0.44, for rupture away from the station, to about 4, for rupture toward the station. In this version of the theory directivity is independent of period. Additionally, we have created another functional form which is c-tilde-prime modified to include the approximate radiation pattern of a finite fault having a given rake. This functional form can be used to model the spatial variations of fault-parallel and fault-normal horizontal ground motions. The strengths of this formulation are 1) the proposed functional form is based on theory, 2) the predictor is unambiguously defined for all possible site locations and source rakes, and 3) it can easily be implemented for well-studied important previous earthquakes. We compare predictions of our functional form with synthetic ground motions calculated for finite strike-slip and dip-slip faults in the magnitude range 6.5 - 7.5. In general our functional form correlates best with computed fault-normal and fault-parallel motions in the synthetic motions calculated for events with M6.5. Correlation degrades but is still useful for larger events and for the geometric average horizontal motions. We have had limited success applying it to geometrically complicated faults.

Frequency-dependent effects of rupture for the 2004 Parkfield mainshock, results from UPSAR

USGS Publications Warehouse

Fletcher, Jon B.

2014-01-01

The frequency-dependent effects of rupture propagation of the Parkfield, California earthquake (Sept. 28, 2004, M6) to the northwest along the San Andreas fault can be seen in acceleration records at UPSAR (USGS Parkfield Seismic Array) in at least two ways. First, we can see the effects of directivity in the acceleration traces at UPSAR, which is about 11.5 km from the epicenter. Directivity or the seismic equivalent of a Doppler shift has been documented in many cases by comparing short duration, high-amplitude pulses (P or S) in the forward direction with longer duration body waves in the backward direction. In this case we detect a change from a relatively large amplitude, coherent, high-frequency signal at the start of rupture to a low-amplitude, low-coherent, low-frequency signal at about the time the rupture front transfers from the forward azimuth to the back azimuth at about 34-36 s (time is UTC and are the seconds after day 272 and 17 hours and 15 minutes. S arrival is just after 30s) for rays leaving the fault and propagating to UPSAR. The frequency change is obvious in the band about 5 to 30 Hz, which is significantly above the corner frequency of the earthquake (about 0.11Hz). From kinematic source models, the duration of faulting is about 9.2 s and the change in frequency is during faulting as the rupture extends to the northwest. Understanding the systematic change in frequency and amplitude of seismic waves in relation to the propagation of the rupture front is important for predicting strong ground motion. Second, we can filter the acceleration records from the array to determine if the low frequency energy emerges from the same part of the fault as the high frequency signal (e.g. has the same back azimuth and apparent velocity at UPSAR) an important clue to the dynamics of rupture. Analysis of sources of strong motion (characterized by relatively high frequencies) compared to kinematic slip models (relatively low frequency) for the March 11, 2011 Tohoku earthquake as well as Maule (Feb. 27, 2010) and Chi-Chi (Sept. 20, 1999) earthquakes show that high- and low-frequency sources do not have the same locations on the fault. In this paper we filter the accelerograms from UPSAR for the 2004 mainshock in various passbands and then re-compute the cross correlations to determine the vector slowness of the incoming waves. At Parkfield, it appears that for seismic waves with frequencies above 1 Hz there is no discernible frequency-dependent difference in source position (up to 8 Hz) based on estimates of back azimuth and apparent velocity. However at lower frequencies, sources appear to be from shallower depths and trail the high frequencies as the rupture proceeds down the fault. This result is greater than one standard deviation of an estimate of error, based on a new method of estimating error that is a measure of how broad the peak in correlation is and an estimate of the variance of the correlation values. These observations can be understood in terms of a rupture front that is more energetic and coherent near the front of rupture (radiating higher frequencies) and less coherent and less energetic (radiating in a lower frequency band) behind the initial rupture front. This result is a qualitative assessment of changes in azimuth and apparent velocity with frequency and time and does not include corrections to find the source location on the fault.

Creep rupture behavior of Stirling engine materials

NASA Technical Reports Server (NTRS)

Titran, R. H.; Scheuerman, C. M.; Stephens, J. R.

1985-01-01

The automotive Stirling engine, being investigated jointly by the Department of Energy and NASA Lewis as an alternate to the internal combustion engine, uses high-pressure hydrogen as the working fluid. The long-term effects of hydrogen on the high temperature strength properties of materials is relatively unknown. This is especially true for the newly developed low-cost iron base alloy NASAUT 4G-A1. This iron-base alloy when tested in air has creep-rupture strengths in the directionally solidified condition comparable to the cobalt base alloy HS-31. The equiaxed (investment cast) NASAUT 4G-A1 has superior creep-rupture to the equiaxed iron-base alloy XF-818 both in air and 15 MPa hydrogen.

Incorporation of forward-directivity into seismic hazard analysis.

DOT National Transportation Integrated Search

2009-01-01

Ground motions in close proximity to the causative fault of an earthquake can be significantly affected by the propagation of : rupture. In particular, when the rupture and slip direction relative to a site coincide and a significant portion of the f...

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.

Modulation of a pulsatile release drug delivery system using different swellable/rupturable materials.

PubMed

El-Maradny, Hoda A

2007-11-01

Diclofenac sodium tablets consisting of core coated with two layers of swelling and rupturable coatings were prepared and evaluated as a pulsatile drug delivery system. Cores containing the drug were prepared by direct compression using microcrystalline cellulose and Ludipress as hydrophilic excipients with the ratio of 1:1. Cores were then coated sequentially with an inner swelling layer of different swellable materials; either Explotab, Croscarmellose sodium, or Starch RX 1500, and an outer rupturable layer of different levels of ethylcellulose. The effect of the nature of the swelling layer and the level of the rupturable coating on the lag time and the water uptake were investigated. Drug release rate studies were performed using USP paddle method. Results showed the dependence of the lag time and water uptake prior to tablet rupture on the nature of the swelling layer and the coating levels. Explotab showed a significant decrease in the lag time, followed by Croscarmellose sodium and finally by Starch RX 1500. Increasing the level of ethylcellulose coating retarded the diffusion of the release medium to the swelling layer and the rupture of the coat, thus prolonging the lag time.

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.

Collective properties of injection-induced earthquake sequences: 1. Model description and directivity bias

NASA Astrophysics Data System (ADS)

Dempsey, David; Suckale, Jenny

2016-05-01

Induced seismicity is of increasing concern for oil and gas, geothermal, and carbon sequestration operations, with several M > 5 events triggered in recent years. Modeling plays an important role in understanding the causes of this seismicity and in constraining seismic hazard. Here we study the collective properties of induced earthquake sequences and the physics underpinning them. In this first paper of a two-part series, we focus on the directivity ratio, which quantifies whether fault rupture is dominated by one (unilateral) or two (bilateral) propagating fronts. In a second paper, we focus on the spatiotemporal and magnitude-frequency distributions of induced seismicity. We develop a model that couples a fracture mechanics description of 1-D fault rupture with fractal stress heterogeneity and the evolving pore pressure distribution around an injection well that triggers earthquakes. The extent of fault rupture is calculated from the equations of motion for two tips of an expanding crack centered at the earthquake hypocenter. Under tectonic loading conditions, our model exhibits a preference for unilateral rupture and a normal distribution of hypocenter locations, two features that are consistent with seismological observations. On the other hand, catalogs of induced events when injection occurs directly onto a fault exhibit a bias toward ruptures that propagate toward the injection well. This bias is due to relatively favorable conditions for rupture that exist within the high-pressure plume. The strength of the directivity bias depends on a number of factors including the style of pressure buildup, the proximity of the fault to failure and event magnitude. For injection off a fault that triggers earthquakes, the modeled directivity bias is small and may be too weak for practical detection. For two hypothetical injection scenarios, we estimate the number of earthquake observations required to detect directivity bias.

Vacation Appendicitis

PubMed Central

Tempel, Michael B.; Harrison, Shannon; Zhu, Xiang

2013-01-01

Objective: When someone plans a vacation, one of the last things taken into consideration is the possibility of contracting an illness while away. Unfortunately, if people develop abdominal pain while planning for a vacation, they usually proceed with the vacation and do not consider getting medical attention for their pain. The purpose of this study was to examine the effect of being on vacation and its association with ruptured appendicitis. Methods: From January 1, 2007 to December 31, 2008, the incidence of ruptured appendicitis cases at Florida Hospital–Celebration Health, located 5 miles from Walt Disney World, was compared with that of Florida Hospital–Orlando, approximately 30 miles away from Walt Disney World. We evaluated whether patients “on vacation” versus residents of Orlando have an increased incidence of ruptured appendicitis. Results: Of patients treated for presumed appendicitis, 60.59% at Florida Hospital–Celebration Health had ruptured appendicitis during this time versus 20.42% at Florida Hospital–Orlando. Of those 266 patients seen at Florida Hospital–Celebration Health, 155 were on vacation versus only 21 at Florida Hospital–Orlando. Conclusion: Although there is not a direct cause and effect, it is clear that there is a higher incidence of ruptured appendicitis in patients on vacation versus in the regular community in the Orlando, Florida area. PMID:23743367

Rupture process of 2016, 25 January earthquake, Alboran Sea (South Spain, Mw= 6.4) and aftershocks series

NASA Astrophysics Data System (ADS)

Buforn, E.; Pro, C.; del Fresno, C.; Cantavella, J.; Sanz de Galdeano, C.; Udias, A.

2016-12-01

We have studied the rupture process of the 25 January 2016 earthquake (Mw =6.4) occurred in South Spain in the Alboran Sea. Main shock, foreshock and largest aftershocks (Mw =4.5) have been relocated using the NonLinLoc algorithm. Results obtained show a NE-SW distribution of foci at shallow depth (less than 15 km). For main shock, focal mechanism has been obtained from slip inversion over the rupture plane of teleseismic data, corresponding to left-lateral strike-slip motion. The rupture starts at 7 km depth and it propagates upward with a complex source time function. In order to obtain a more detailed source time function and to validate the results obtained from teleseismic data, we have used the Empirical Green Functions method (EGF) at regional distances. Finally, results of the directivity effect from teleseismic Rayleigh waves and the EGF method, are consistent with a rupture propagation to the NE. These results are interpreted in terms of the main geological features in the region.

Ground Motion Simulation for a Large Active Fault System using Empirical Green's Function Method and the Strong Motion Prediction Recipe - a Case Study of the Noubi Fault Zone -

NASA Astrophysics Data System (ADS)

Kuriyama, M.; Kumamoto, T.; Fujita, M.

2005-12-01

The 1995 Hyogo-ken Nambu Earthquake (1995) near Kobe, Japan, spurred research on strong motion prediction. To mitigate damage caused by large earthquakes, a highly precise method of predicting future strong motion waveforms is required. In this study, we applied empirical Green's function method to forward modeling in order to simulate strong ground motion in the Noubi Fault zone and examine issues related to strong motion prediction for large faults. Source models for the scenario earthquakes were constructed using the recipe of strong motion prediction (Irikura and Miyake, 2001; Irikura et al., 2003). To calculate the asperity area ratio of a large fault zone, the results of a scaling model, a scaling model with 22% asperity by area, and a cascade model were compared, and several rupture points and segmentation parameters were examined for certain cases. A small earthquake (Mw: 4.6) that occurred in northern Fukui Prefecture in 2004 were examined as empirical Green's function, and the source spectrum of this small event was found to agree with the omega-square scaling law. The Nukumi, Neodani, and Umehara segments of the 1891 Noubi Earthquake were targeted in the present study. The positions of the asperity area and rupture starting points were based on the horizontal displacement distributions reported by Matsuda (1974) and the fault branching pattern and rupture direction model proposed by Nakata and Goto (1998). Asymmetry in the damage maps for the Noubi Earthquake was then examined. We compared the maximum horizontal velocities for each case that had a different rupture starting point. In the case, rupture started at the center of the Nukumi Fault, while in another case, rupture started on the southeastern edge of the Umehara Fault; the scaling model showed an approximately 2.1-fold difference between these cases at observation point FKI005 of K-Net. This difference is considered to relate to the directivity effect associated with the direction of rupture propagation. Moreover, it was clarified that the horizontal velocities by assuming the cascade model was underestimated more than one standard deviation of empirical relation by Si and Midorikawa (1999). The scaling and cascade models showed an approximately 6.4-fold difference for the case, in which the rupture started along the southeastern edge of the Umehara Fault at observation point GIF020. This difference is significantly large in comparison with the effect of different rupture starting points, and shows that it is important to base scenario earthquake assumptions on active fault datasets before establishing the source characterization model. The distribution map of seismic intensity for the 1891 Noubi Earthquake also suggests that the synthetic waveforms in the southeastern Noubi Fault zone may be underestimated. Our results indicate that outer fault parameters (e.g., earthquake moment) related to the construction of scenario earthquakes influence strong motion prediction, rather than inner fault parameters such as the rupture starting point. Based on these methods, we will predict strong motion for approximately 140 to 150 km of the Itoigawa-Shizuoka Tectonic Line.

Morphological and clinical risk factors for posterior communicating artery aneurysm rupture.

PubMed

Matsukawa, Hidetoshi; Fujii, Motoharu; Akaike, Gensuke; Uemura, Akihiro; Takahashi, Osamu; Niimi, Yasunari; Shinoda, Masaki

2014-01-01

Recent studies have shown that posterior circulation aneurysms, specifically posterior communicating artery (PCoA) aneurysms, are more likely to rupture than other aneurysms. To date, few studies have investigated the factors contributing to PCoA aneurysm rupture. The authors aimed to identify morphological and clinical characteristics predisposing to PCoA aneurysm rupture. The authors retrospectively reviewed 134 consecutive patients with PCoA aneurysms managed at their facility between July 2003 and December 2012. The authors divided patients into groups of those with aneurysmal rupture (n = 39) and without aneurysmal rupture (n = 95) and compared morphological and clinical characteristics. Morphological characteristics were mainly evaluated by 3D CT angiography and included diameter of arteries (anterior cerebral artery, middle cerebral artery, and internal carotid artery), size of the aneurysm, dome-to-neck ratio, neck direction of the aneurysmal dome around the PCoA (medial, lateral, superior, inferior, and posterior), aneurysm bleb formation, whether the PCoA was fetal type, and the existence of other intracranial unruptured aneurysm(s). Patients with ruptured PCoA aneurysms were significantly younger (a higher proportion were < 60 years of age) and a significantly higher proportion of patients with ruptured PCoA aneurysms showed a lateral direction of the aneurysmal dome around the PCoA, had bleb formation, and the aneurysm was > 7 mm in diameter and/or the dome-to-neck ratio was > 2.0. Multivariate logistic regression analysis showed age < 60 years (OR 4.3, p = 0.011), history of hypertension (OR 5.1, p = 0.008), lateral direction of the aneurysmal dome around the PCoA (OR 6.7, p = 0.0001), and bleb formation (OR 11, p < 0.0001) to be significantly associated with PCoA aneurysm rupture. The present results demonstrated that lateral projection of a PCoA aneurysm may be related to rupture.

Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms

NASA Astrophysics Data System (ADS)

Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng

2013-04-01

Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.

Rupture process of the 2013 Okhotsk deep mega earthquake from iterative backprojection and compress sensing methods

NASA Astrophysics Data System (ADS)

Qin, W.; Yin, J.; Yao, H.

2013-12-01

On May 24th 2013 a Mw 8.3 normal faulting earthquake occurred at a depth of approximately 600 km beneath the sea of Okhotsk, Russia. It is a rare mega earthquake that ever occurred at such a great depth. We use the time-domain iterative backprojection (IBP) method [1] and also the frequency-domain compressive sensing (CS) technique[2] to investigate the rupture process and energy radiation of this mega earthquake. We currently use the teleseismic P-wave data from about 350 stations of USArray. IBP is an improved method of the traditional backprojection method, which more accurately locates subevents (energy burst) during earthquake rupture and determines the rupture speeds. The total rupture duration of this earthquake is about 35 s with a nearly N-S rupture direction. We find that the rupture is bilateral in the beginning 15 seconds with slow rupture speeds: about 2.5km/s for the northward rupture and about 2 km/s for the southward rupture. After that, the northward rupture stopped while the rupture towards south continued. The average southward rupture speed between 20-35 s is approximately 5 km/s, lower than the shear wave speed (about 5.5 km/s) at the hypocenter depth. The total rupture length is about 140km, in a nearly N-S direction, with a southward rupture length about 100 km and a northward rupture length about 40 km. We also use the CS method, a sparse source inversion technique, to study the frequency-dependent seismic radiation of this mega earthquake. We observe clear along-strike frequency dependence of the spatial and temporal distribution of seismic radiation and rupture process. The results from both methods are generally similar. In the next step, we'll use data from dense arrays in southwest China and also global stations for further analysis in order to more comprehensively study the rupture process of this deep mega earthquake. Reference [1] Yao H, Shearer P M, Gerstoft P. Subevent location and rupture imaging using iterative backprojection for the 2011 Tohoku Mw 9.0 earthquake. Geophysical Journal International, 2012, 190(2): 1152-1168. [2]Yao H, Gerstoft P, Shearer P M, et al. Compressive sensing of the Tohoku-Oki Mw 9.0 earthquake: Frequency-dependent rupture modes. Geophysical Research Letters, 2011, 38(20).

Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity

NASA Astrophysics Data System (ADS)

Chounet, Agnès; Vallée, Martin; Causse, Mathieu; Courboulex, Françoise

2018-05-01

Application of the SCARDEC method provides the apparent source time functions together with seismic moment, depth, and focal mechanism, for most of the recent earthquakes with magnitude larger than 5.6-6. Using this large dataset, we have developed a method to systematically invert for the rupture direction and average rupture velocity Vr, when unilateral rupture propagation dominates. The approach is applied to all the shallow (z < 120 km) earthquakes of the catalog over the 1992-2015 time period. After a careful validation process, rupture properties for a catalog of 96 earthquakes are obtained. The subsequent analysis of this catalog provides several insights about the seismic rupture process. We first report that up-dip ruptures are more abundant than down-dip ruptures for shallow subduction interface earthquakes, which can be understood as a consequence of the material contrast between the slab and the overriding crust. Rupture velocities, which are searched without any a-priori up to the maximal P wave velocity (6000-8000 m/s), are found between 1200 m/s and 4500 m/s. This observation indicates that no earthquakes propagate over long distances with rupture velocity approaching the P wave velocity. Among the 23 ruptures faster than 3100 m/s, we observe both documented supershear ruptures (e.g. the 2001 Kunlun earthquake), and undocumented ruptures that very likely include a supershear phase. We also find that the correlation of Vr with the source duration scaled to the seismic moment (Ts) is very weak. This directly implies that both Ts and Vr are anticorrelated with the stress drop Δσ. This result has implications for the assessment of the peak ground acceleration (PGA) variability. As shown by Causse and Song (2015), an anticorrelation between Δσ and Vr significantly reduces the predicted PGA variability, and brings it closer to the observed variability.

Estimating Rupture Directivity of Aftershocks of the 2014 Mw8.1 Iquique Earthquake, Northern Chile

NASA Astrophysics Data System (ADS)

Folesky, Jonas; Kummerow, Jörn; Timann, Frederik; Shapiro, Serge

2017-04-01

The 2014 Mw8.1 Iquique earthquake was accompanied by numerous fore- and aftershocks of magnitudes up to M ˜ 7.6. While the rupture processes of the main event and its largest aftershock were already analysed in great detail, this study focusses on the rupture processes of about 230 smaller aftershocks that occurred during the first two days after the main event. Since the events are of magnitudes 4.0 ≤ M ≤ 6.5 it is not trivial which method is most suitable. Thus we apply and compare here three different approaches attempting to extract a possible rupture directivity for each single event. The seismic broadband recordings of the Integrated Plate Boundary Observatory Chile (IPOC) provide an excellent database for our analysis. Their high sampling rate (100 Hz) and a well distributed station selection that cover an aperture of about 180 ° are a great advantage for a thorough directivity analysis. First, we apply a P wave polarization analysis (PPA) where we reconstruct the direction of the incoming wave-field by covariance analysis of the first particle motions. Combined with a sliding time window the results from different stations are capable of identifying first the hypocentre of the events and also a migration of the rupture front, if the event is of unilateral character. A second approach is the back projection imaging (BPI) technique, which illuminates the rupture path by back-projecting the recorded seismic energy to its source. A propagating rupture front would be reconstructed from the migration of the zone of high constructive amplitude stacks. In a third step we apply the empirical Green's function (EGF) method, where events of high waveform similarity, hence co-located and of similar mechanisms, are selected in order to use the smaller event as the Green's function of the larger event. This approach results in an estimated source time function, which is compared station wise and whose azimuthal variations are analysed for complexities and directivity.

Coseismic temporal changes of slip direction: the effect of absolute stress on dynamic rupture

USGS Publications Warehouse

Guatteri, Mariagiovanna; Spudich, P.

1998-01-01

We investigate the dynamics of rupture at low-stress level. We show that one main difference between the dynamics of high- and low-stress events is the amount of coseismic temporal rake rotation occurring at given points on the fault. Curved striations on exposed fault surfaces and earthquake dislocation models derived from ground-motion inversion indicate that the slip direction may change with time at a point on the fault during dynamic rupture. We use a 3D boundary integral method to model temporal rake variations during dynamic rupture propagation assuming a slip-weakening friction law and isotropic friction. The points at which the slip rotates most are characterized by an initial shear stress direction substantially different from the average stress direction over the fault plane. We show that for a given value of stress drop, the level of initial shear stress (i.e., the fractional stress drop) determines the amount of rotation in slip direction. We infer that seismic events that show evidence of temporal rake rotations are characterized by a low initial shear-stress level with spatially variable direction on the fault (possibly due to changes in fault surface geometry) and an almost complete stress drop.Our models motivate a new interpretation of curved and cross-cutting striations and put new constraints on their analysis. The initial rake is in general collinear with the initial stress at the hypocentral zone, supporting the assumptions made in stress-tensor inversion from first-motion analysis. At other points on the fault, especially away from the hypocenter, the initial slip rake may not be collinear with the initial shear stress, contradicting a common assumption of structural geology. On the other hand, the later part of slip in our models is systematically more aligned with the average stress direction than the early slip. Our modeling suggests that the length of the straight part of curved striations is usually an upper bound of the slip-weakening distance if this parameter is uniform over the fault plane, and the direction of the late part of slip of curved striations should have more weight in the estimate of initial stress direction.

Directly Estimating Earthquake Rupture Area using Second Moments to Reduce the Uncertainty in Stress Drop

NASA Astrophysics Data System (ADS)

McGuire, Jeffrey J.; Kaneko, Yoshihiro

2018-06-01

The key kinematic earthquake source parameters: rupture velocity, duration and area, shed light on earthquake dynamics, provide direct constraints on stress-drop, and have implications for seismic hazard. However, for moderate and small earthquakes, these parameters are usually poorly constrained due to limitations of the standard analysis methods. Numerical experiments by Kaneko and Shearer [2014,2015] demonstrated that standard spectral fitting techniques can lead to roughly 1 order of magnitude variation in stress-drop estimates that do not reflect the actual rupture properties even for simple crack models. We utilize these models to explore an alternative approach where we estimate the rupture area directly. For the suite of models, the area averaged static stress drop is nearly constant for models with the same underlying friction law, yet corner frequency based stress-drop estimates vary by a factor of 5-10 even for noise free data. Alternatively, we simulated inversions for the rupture area as parameterized by the second moments of the slip distribution. A natural estimate for the rupture area derived from the second moments is A=πLcWc, where Lc and Wc are the characteristic rupture length and width. This definition yields estimates of stress drop that vary by only 10% between the models but are slightly larger than the true area-averaged values. We simulate inversions for the second moments for the various models and find that the area can be estimated well when there are at least 15 available measurements of apparent duration at a variety of take-off angles. The improvement compared to azimuthally-averaged corner-frequency based approaches results from the second moments accounting for directivity and removing the assumption of a circular rupture area, both of which bias the standard approach. We also develop a new method that determines the minimum and maximum values of rupture area that are consistent with a particular dataset at the 95% confidence level. For the Kaneko and Shearer models with 20+ randomly distributed observations and ˜10% noise levels, we find that the maximum and minimum bounds on rupture area typically vary by a factor of two and that the minimum stress drop is often more tightly constrained than the maximum.

Determination of differential arrival times by cross-correlating worldwide seismological data

NASA Astrophysics Data System (ADS)

Godano, M.; Nolet, G.; Zaroli, C.

2012-12-01

Cross-correlation delays are the preferred body wave observables in global tomography. Heterogeneity is the main factor influencing delay times found by cross-correlation. Not only the waveform, but also the arrival time itself is affected by differences in seismic velocity encountered along the way. An accurate method for estimating differential times of seismic arrivals across a regional array by cross-correlation was developed by VanDecar and Crosson [1990]. For the estimation of global travel time delays in different frequency bands, Sigloch and Nolet [2006] developed a method for the estimation of body wave delays using a matched filter, which requires the separate estimation of the source time function. Sigloch et al. [2008] found that waveforms often cluster in and opposite the direction of rupture propagation on the fault, confirming that the directivity effect is a major factor in shaping the waveform of large events. We propose a generalization of the VanDecar-Crosson method to which we add a correction for the directivity effect in the seismological data. The new method allows large events to be treated without the need to estimate the source time function for the computation of a matched synthetic waveform. The procedure consists in (1) the detection of the directivity effect in the data and the determination of a rupture model (unilateral or bilateral) explaining the differences in pulse duration among the stations, (2) the determination of an apparent fault rupture length explaining the pulse durations, (3) the removal of the delay due to the directivity effect in the pulse duration , by stretching or contracting the seismograms for directive and anti-directive stations respectively and (4) the application of a generalized VanDecar and Crosson method using only delays between pairs of stations that have an acceptable correlation coefficient. We validate our method by performing tests on synthetic data. Results show that the error between theoretical and measured differential arrival time are significantly reduced for the corrected data. We illustrate our method on data from several real earthquakes.

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.

Structure and creep rupture properties of directionally solidified eutectic gamma/gamma-prime-alpha alloy

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.; Wirth, G.

1982-01-01

A simple ternary gamma/gamma-prime-alpha alloy of nominal composition (wt-%) Ni-32Mo-6Al has been directionally solidified at 17 mm/h and tested in creep rupture at 1073, 1173, and 1273 K. A uniform microstructure consisting of square-shaped Mo fibers in a gamma + gamma-prime matrix was found despite some variation in the molybdenum and aluminum concentrations along the growth direction. Although the steady-state creep rate is well described by the normal stress temperature equation, the stress exponent (12) and the activation energy (580 kJ/mol) are high. The rupture behavior is best characterized by the Larson-Miller parameter where the constant equals 20.

77 FR 32437 - Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-01

... different compliance time. We are proposing this AD to prevent rupture of a gas generator (GG) turbine blade... rupture of a gas generator (GG) turbine blade, which could result in an uncommanded in-flight shutdown and... AD resulted from several cases of GG turbine blade rupture occurring in service on Arriel 2 twin...

Recent updates in developing a statistical pseudo-dynamic source-modeling framework to capture the variability of earthquake rupture scenarios

NASA Astrophysics Data System (ADS)

Song, Seok Goo; Kwak, Sangmin; Lee, Kyungbook; Park, Donghee

2017-04-01

It is a critical element to predict the intensity and variability of strong ground motions in seismic hazard assessment. The characteristics and variability of earthquake rupture process may be a dominant factor in determining the intensity and variability of near-source strong ground motions. Song et al. (2014) demonstrated that the variability of earthquake rupture scenarios could be effectively quantified in the framework of 1-point and 2-point statistics of earthquake source parameters, constrained by rupture dynamics and past events. The developed pseudo-dynamic source modeling schemes were also validated against the recorded ground motion data of past events and empirical ground motion prediction equations (GMPEs) at the broadband platform (BBP) developed by the Southern California Earthquake Center (SCEC). Recently we improved the computational efficiency of the developed pseudo-dynamic source-modeling scheme by adopting the nonparametric co-regionalization algorithm, introduced and applied in geostatistics initially. We also investigated the effect of earthquake rupture process on near-source ground motion characteristics in the framework of 1-point and 2-point statistics, particularly focusing on the forward directivity region. Finally we will discuss whether the pseudo-dynamic source modeling can reproduce the variability (standard deviation) of empirical GMPEs and the efficiency of 1-point and 2-point statistics to address the variability of ground motions.

Combined Angio-Seal™ and stenting rescue treatment in a case of iatrogenic common carotid artery dissection during direct puncture for ruptured intracranial aneurysm embolization: a technical note.

PubMed

Iosif, Christina; Clarençon, Frédéric; Di Maria, Federico; Law-Ye, Bruno; Le Jean, Lise; Capelle, Laurent; Chiras, Jacques; Sourour, Nader

2013-05-01

Direct puncture may offer an alternative access for embolization of intracranial aneurysms in patients presenting with tortuous vessels. Nevertheless, major complications such as compressive hematoma and arterial dissection can occur with this technique. A tight common carotid artery (CCA) dissection was seen secondary to direct puncture in a 72-year-old patient who presented with a ruptured anterior communicating artery (ACom) aneurysm. After regular coiling of the aneurysm and using a femoral approach, an Angio-Seal™ device (St Jude Medical, Saint Paul, MN, USA) was placed and a carotid wallstent (Stryker Neurovascular, Fremont, CA, USA) successfully deployed at the dissected CCA, which was followed by good clinical and angiographic outcomes. A combined rescue technique combining Angio-Seal insertion and stent deployment was safe and effective for managing iatrogenic carotid artery dissection. Copyright © 2013. Published by Elsevier Masson SAS.

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.

Entropic-elasticity-controlled dissociation and energetic-elasticity-controlled rupture induce catch-to-slip bonds in cell-adhesion molecules.

PubMed

Wei, YuJie

2008-03-01

We develop a physical model to describe the kinetic behavior in cell-adhesion molecules. Unbinding of noncovalent biological bonds is assumed to occur by both bond dissociation and bond rupture. Such a decomposition of debonding processes is a space decomposition of the debonding events. Dissociation under thermal fluctuation is nondirectional in a three-dimensional space, and its energy barrier to escape is not influenced by a tensile force, but the microstates that could lead to dissociation are changed by the tensile force; rupture happens along the tensile force direction. An applied force effectively lowers the energy barrier to escape along the loading direction. The lifetime of the biological bond, due to the two concurrent off rates, may grow with increasing tensile force to a moderate amount and then decrease with further increasing load. We hypothesize that a catch-to-slip bond transition is a generic feature in biological bonds. The model also predicts that catch bonds in a more flexible molecular structure have longer lifetimes and need less force to be fully activated.

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.

Intraluminal cell transplantation prevents growth and rupture in a model of rupture-prone saccular aneurysms.

PubMed

Marbacher, Serge; Frösén, Juhana; Marjamaa, Johan; Anisimov, Andrey; Honkanen, Petri; von Gunten, Michael; Abo-Ramadan, Usama; Hernesniemi, Juha; Niemelä, Mika

2014-12-01

Aneurysm occlusion by intraluminal thrombus formation is the desired effect of all endovascular treatments. Intraluminal thrombus may, however, recanalize and be absorbed, unless it is infiltrated by cells that turn it into fibrous tissue (neointima). Because ruptured aneurysm walls are characterized by loss of smooth muscle cells, we assessed the impact of mural cell loss on wall remodeling of thrombosed aneurysms and investigated whether neointima formation could be enhanced by direct transplantation of cells into the thrombus. Sidewall aneurysms were microsurgically created in rats (n=81). Certain aneurysms were decellularized. Thrombosis was induced using direct injection of a fibrin polymer into the aneurysm. CM-Dil-labeled smooth muscle cells were injected into 25 of 46 fibrin embolized aneurysms. Recanalization and aneurysm growth were monitored with magnetic resonance angiography. Endoscopy, optical projection tomography, histology, and immunohistochemistry were used to study the fate of transplanted cells, thrombus organization, and neointima formation. Decellularized embolized aneurysms demonstrated higher angiographic recurrence compared with decellularized embolized aneurysms with transplanted cells (P=0.037). Local cell replacement at the time of thrombosis resulted in better histological neointima formation than both nondecellularized embolized aneurysms (P<0.001) and decellularized embolized aneurysms (P=0.002). Aneurysm growth and rupture were observed exclusively in decellularized embolized aneurysms. Lack of smooth muscle cells in the aneurysm wall promotes wall degradation, aneurysm growth and rupture, even if the aneurysm is occluded by luminal thrombus. Transplantation of smooth muscle cells into the luminal thrombus can reduce this degenerative remodeling. © 2014 American Heart Association, Inc.

Application of Second-Moment Source Analysis to Three Problems in Earthquake Forecasting

NASA Astrophysics Data System (ADS)

Donovan, J.; Jordan, T. H.

2011-12-01

Though earthquake forecasting models have often represented seismic sources as space-time points (usually hypocenters), a more complete hazard analysis requires the consideration of finite-source effects, such as rupture extent, orientation, directivity, and stress drop. The most compact source representation that includes these effects is the finite moment tensor (FMT), which approximates the degree-two polynomial moments of the stress glut by its projection onto the seismic (degree-zero) moment tensor. This projection yields a scalar space-time source function whose degree-one moments define the centroid moment tensor (CMT) and whose degree-two moments define the FMT. We apply this finite-source parameterization to three forecasting problems. The first is the question of hypocenter bias: can we reject the null hypothesis that the conditional probability of hypocenter location is uniformly distributed over the rupture area? This hypothesis is currently used to specify rupture sets in the "extended" earthquake forecasts that drive simulation-based hazard models, such as CyberShake. Following McGuire et al. (2002), we test the hypothesis using the distribution of FMT directivity ratios calculated from a global data set of source slip inversions. The second is the question of source identification: given an observed FMT (and its errors), can we identify it with an FMT in the complete rupture set that represents an extended fault-based rupture forecast? Solving this problem will facilitate operational earthquake forecasting, which requires the rapid updating of earthquake triggering and clustering models. Our proposed method uses the second-order uncertainties as a norm on the FMT parameter space to identify the closest member of the hypothetical rupture set and to test whether this closest member is an adequate representation of the observed event. Finally, we address the aftershock excitation problem: given a mainshock, what is the spatial distribution of aftershock probabilities? The FMT representation allows us to generalize the models typically used for this purpose (e.g., marked point process models, such as ETAS), which will again be necessary in operational earthquake forecasting. To quantify aftershock probabilities, we compare mainshock FMTs with the first and second spatial moments of weighted aftershock hypocenters. We will describe applications of these results to the Uniform California Earthquake Rupture Forecast, version 3, which is now under development by the Working Group on California Earthquake Probabilities.

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

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.

Spontaneous distal rupture of the plantar fascia.

PubMed

Gitto, Salvatore; Draghi, Ferdinando

2018-07-01

Spontaneous ruptures of the plantar fascia are uncommon injuries. They typically occur at its calcaneal insertion and usually represent a complication of plantar fasciitis and local treatment with steroid injections. In contrast, distal ruptures commonly result from traumatic injuries. We describe the case of a spontaneous distal rupture of the plantar fascia in a 48-year-old woman with a low level of physical activity and no history of direct injury to the foot, plantar fasciitis, or steroid injections. © 2017 Wiley Periodicals, Inc.

Mast cell curve-response in partial Achilles tendon rupture after 830 nm phototherapy.

PubMed

Pinfildi, Carlos E; da Silva, Érika P Rampazo; Folha, Roberta A C; Turchetto, Paola C G; Monteiro, Paola Pkp; Antunes, Arainy; Hochman, Bernardo S

2014-02-01

The aim of this study was to quantify mast cells at different time intervals after partial Achilles tendon rupture in rats treated with low-level laser therapy (LLLT). There is a high incidence of lesions and ruptures in the Achilles tendon that can take weeks and even months to heal completely. As the mast cells help in the healing repair phase, and LLLT has favorable effects on this tissue repair process, study of this modality on the quantity of mastocytes in the ruptured tendon is relevant. Sixty Wistar rats were subjected to partial Achilles' tendon rupture by direct trauma, randomized into 10 groups, and then divided into the group treated with 80 mW aluminum gallium arsenide infrared laser diode, continuous wave, 2.8 W/cm(2) power density, 40 J/cm(2) energy density, and 1.12 J total energy, and the simulation group. Both the groups were subdivided according to the histological assessment period of the sample, either 6 h, 12 h, 24 h, 2 days, or 3 days after the rupture, to quantify the mastocytes in the Achilles' tendon. The group subjected to LLLT presented a greater quantity of mastocytes in the periods of 6 h, 12 h, 24 h, 2 days, and 3 days after rupture, compared with the simulation groups, but differences were detected between the sample assessment periods only in the simulation group. LLLT was shown to increase the quantity of mastocytes in the assessment periods compared with the simulation groups.

Ground-motion modeling of Hayward fault scenario earthquakes, part II: Simulation of long-period and broadband ground motions

USGS Publications Warehouse

Aagaard, Brad T.; Graves, Robert W.; Rodgers, Arthur; Brocher, Thomas M.; Simpson, Robert W.; Dreger, Douglas; Petersson, N. Anders; Larsen, Shawn C.; Ma, Shuo; Jachens, Robert C.

2010-01-01

We simulate long-period (T>1.0–2.0 s) and broadband (T>0.1 s) ground motions for 39 scenario earthquakes (Mw 6.7–7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault, we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions, compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area, with about 50% of the urban area experiencing modified Mercalli intensity VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18 Oakland earthquake and the 2007 Mw 5.45 Alum Rock earthquake show that the U.S. Geological Survey’s Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area for Hayward fault earthquakes, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions for the suite of scenarios exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the Next Generation Attenuation (NGA) ground-motion prediction equations. We attribute much of this difference to the seismic velocity structure in the San Francisco Bay area and how the NGA models account for basin amplification; the NGA relations may underpredict amplification in shallow sedimentary basins. The simulations also suggest that the Spudich and Chiou (2008) directivity corrections to the NGA relations could be improved by increasing the areal extent of rupture directivity with period.

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.

Characterize kinematic rupture history of large earthquakes with Multiple Haskell sources

NASA Astrophysics Data System (ADS)

Jia, Z.; Zhan, Z.

2017-12-01

Earthquakes are often regarded as continuous rupture along a single fault, but the occurrence of complex large events involving multiple faults and dynamic triggering challenges this view. Such rupture complexities cause difficulties in existing finite fault inversion algorithms, because they rely on specific parameterizations and regularizations to obtain physically meaningful solutions. Furthermore, it is difficult to assess reliability and uncertainty of obtained rupture models. Here we develop a Multi-Haskell Source (MHS) method to estimate rupture process of large earthquakes as a series of sub-events of varying location, timing and directivity. Each sub-event is characterized by a Haskell rupture model with uniform dislocation and constant unilateral rupture velocity. This flexible yet simple source parameterization allows us to constrain first-order rupture complexity of large earthquakes robustly. Additionally, relatively few parameters in the inverse problem yields improved uncertainty analysis based on Markov chain Monte Carlo sampling in a Bayesian framework. Synthetic tests and application of MHS method on real earthquakes show that our method can capture major features of large earthquake rupture process, and provide information for more detailed rupture history analysis.

Blood vessel rupture by cavitation

PubMed Central

Chen, Hong; Brayman, Andrew A.; Bailey, Michael R.

2011-01-01

Cavitation is thought to be one mechanism for vessel rupture during shock wave lithotripsy treatment. However, just how cavitation induces vessel rupture remains unknown. In this work, a high-speed photomicrography system was set up to directly observe the dynamics of bubbles inside blood vessels in ex vivo rat mesenteries. Vascular rupture correlating to observed bubble dynamics were examined by imaging bubble extravasation and dye leakage. The high-speed images show that bubble expansion can cause vessel distention, and bubble collapse can lead to vessel invagination. Liquid jets were also observed to form. Our results suggest that all three mechanisms, vessel distention, invagination and liquid jets, can contribute to vessel rupture. PMID:20680255

Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression

NASA Astrophysics Data System (ADS)

Tarasov, Boris G.

2014-05-01

Today, frictional shear resistance along pre-existing faults is considered to be the lower limit on rock shear strength for confined conditions corresponding to the seismogenic layer. This paper introduces a recently identified shear rupture mechanism providing a paradoxical feature of hard rocks - the possibility of shear rupture propagation through the highly confined intact rock mass at shear stress levels significantly less than frictional strength. In the new mechanism, the rock failure associated with consecutive creation of small slabs (known as ‘domino-blocks') from the intact rock in the rupture tip is driven by a fan-shaped domino structure representing the rupture head. The fan-head combines such unique features as: extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Due to this the failure process caused by the mechanism is very dynamic and violent. This makes it impossible to directly observe and study the mechanism and can explain why the mechanism has not been detected before. This paper provides physical motivation for the mechanism, based upon side effects accompanying the failure process. Physical and mathematical models of the mechanism presented in the paper explain unique and paradoxical features of the mechanism. The new shear rupture mechanism allows a novel point of view for understanding the nature of spontaneous failure processes in hard rocks including earthquakes.

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.

Experimental Investigation on the Basic Law of Directional Hydraulic Fracturing Controlled by Dense Linear Multi-Hole Drilling

NASA Astrophysics Data System (ADS)

Zhao, Xinglong; Huang, Bingxiang; Wang, Zhen

2018-06-01

Directional rupture is a significant and routine problem for ground control in mines. Directional hydraulic fracturing controlled by dense linear multi-hole drilling was proposed. The physical model experiment, performed by the large-scale true triaxial hydraulic fracturing experimental system, aims to investigate the basic law of directional hydraulic fracturing controlled by dense linear multi-hole drilling, the impact of three different pumping modes on the initiation and propagation of hydraulic fractures among boreholes are particular investigated. The experimental results indicated that there are mutual impacts among different boreholes during crack propagation, which leads to a trend of fracture connection. Furthermore, during propagation, the fractures not only exhibit an overall bias toward the direction in which the boreholes are scattered but also partially offset against the borehole axes and intersect. The directional fracturing effect of equivalent pumping rate in each borehole is better than the other two pumping modes. In practical applications, because of rock mass heterogeneity, there may be differences in terms of filtration rate and effective input volume in different boreholes; thus, water pressure increase and rupture are not simultaneous in different boreholes. Additionally, if the crack initiation directions of different boreholes at different times are not consistent with each other, more lamellar failure planes will occur, and the mutual influences of these lamellar failure planes cause fractures to extend and intersect.

Rupture Processes of the Mw8.3 Sea of Okhotsk Earthquake and Aftershock Sequences from 3-D Back Projection Imaging

NASA Astrophysics Data System (ADS)

Jian, P. R.; Hung, S. H.; Meng, L.

2014-12-01

On May 24, 2013, the largest deep earthquake ever recorded in history occurred on the southern tip of the Kamchatka Island, where the Pacific Plate subducts underneath the Okhotsk Plate. Previous 2D beamforming back projection (BP) of P- coda waves suggests the mainshock ruptured bilaterally along a horizontal fault plane determined by the global centroid moment tensor solution. On the other hand, the multiple point source inversion of P and SH waveforms argued that the earthquake comprises a sequence of 6 subevents not located on a single plane but actually distributed in a zone that extends 64 km horizontally and 35 km in depth. We then apply a three-dimensional MUSIC BP approach to resolve the rupture processes of the manishock and two large aftershocks (M6.7) with no a priori setup of preferential orientations of the planar rupture. The maximum pseudo-spectrum of high-frequency P wave in a sequence of time windows recorded by the densely-distributed stations from US and EU Array are used to image 3-D temporal and spatial rupture distribution. The resulting image confirms that the nearly N-S striking but two antiparallel rupture stages. The first subhorizontal rupture initially propagates toward the NNE direction, while at 18 s later it directs reversely to the SSW and concurrently shifts downward to 35 km deeper lasting for about 20 s. The rupture lengths in the first NNE-ward and second SSW-ward stage are about 30 km and 85 km; the estimated rupture velocities are 3 km/s and 4.25 km/s, respectively. Synthetic experiments are undertaken to assess the capability of the 3D MUSIC BP for the recovery of spatio-temporal rupture processes. Besides, high frequency BP images based on the EU-Array data show two M6.7 aftershocks are more likely to rupture on the vertical fault planes.

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.

A N-S fossil transform fault reactivated by the March 2, 2016 Mw7.8 southwest of Sumatra, Indonesia earthquake

NASA Astrophysics Data System (ADS)

Zhang, H.; van der Lee, S.

2016-12-01

Warton Basin (WB) is characterized by N-S striking fossil transform faults and E-W trending extinct ridges. The 2016 Mw7.8 southwest of Sumatra earthquake, nearby the WB's center, was first imaged by back-projecting P-waves from three regional seismic networks in Europn, Japan, and Australia. Next, the rupture direction of the earthquake was further determined using the rupture directivity analysis to P-waves from the global seismic network (GSN). Finally, we inverting these GSN waveforms on a defined N-S striking vertical fault for a kinematic source model. The results show that the earthquake reactivates a 190 degree N-S striking vertical fossil transform fault and asymmetrically bilaterally ruptures a 65 km by 30 km asperity over 35 s. Specifically, the earthquake first bilaterally ruptures northward and southward at a speed of 1.0 km/s over the first 12 s, and then mainly rupture northward at a speed of 1.6 km/s. Compared with two previous M≥7.8 WB earthquakes, including the 2000 southern WB earthquake and 2012 Mw8.6 Sumatra earthquake, the lower seismic energy radiation efficiency and slower rupture velicity of the 2016 earthquake indicate the rupture of the earthquake is probably controlled by the warmer ambient slab and tectonic stress regime.

3-D Dynamic rupture simulation for the 2016 Kumamoto, Japan, earthquake sequence: Foreshocks and M6 dynamically triggered event

NASA Astrophysics Data System (ADS)

Ando, R.; Aoki, Y.; Uchide, T.; Imanishi, K.; Matsumoto, S.; Nishimura, T.

2016-12-01

A couple of interesting earthquake rupture phenomena were observed associated with the sequence of the 2016 Kumamoto, Japan, earthquake sequence. The sequence includes the April 15, 2016, Mw 7.0, mainshock, which was preceded by multiple M6-class foreshock. The mainshock mainly broke the Futagawa fault segment striking NE-SW direction extending over 50km, and it further triggered a M6-class earthquake beyond the distance more than 50km to the northeast (Uchide et al., 2016, submitted), where an active volcano is situated. Compiling the data of seismic analysis and InSAR, we presumed this dynamic triggering event occurred on an active fault known as Yufuin fault (Ando et al., 2016, JPGU general assembly). It is also reported that the coseismic slip was significantly large at a shallow portion of Futagawa Fault near Aso volcano. Since the seismogenic depth becomes significantly shallower in these two areas, we presume the geothermal anomaly play a role as well as the elasto-dynamic processes associated with the coseismic rupture. In this study, we conducted a set of fully dynamic simulations of the earthquake rupture process by assuming the inferred 3D fault geometry and the regional stress field obtained referring the stress tensor inversion. As a result, we showed that the dynamic rupture process was mainly controlled by the irregularity of the fault geometry subjected to the gently varying regional stress field. The foreshocks ruptures have been arrested at the juncture of the branch faults. We also show that the dynamic triggering of M-6 class earthquakes occurred along the Yufuin fault segment (located 50 km NE) because of the strong stress transient up to a few hundreds of kPa due to the rupture directivity effect of the M-7 event. It is also shown that the geothermal condition may lead to the susceptible condition of the dynamic triggering by considering the plastic shear zone on the down dip extension of the Yufuin segment, situated in the vicinity of an active volcano.

Rupture dimensions of the 1998 Antarctic Earthquake from low-frequency waves

NASA Astrophysics Data System (ADS)

McGuire, Jeffrey J.; Zhao, Li; Jordan, Thomas H.

2000-08-01

We inverted frequency dependent phase and amplitude measurements from 1st orbit Rayleigh waves at global stations for the 1st and 2nd degree polynomial moments of the stress-glut rate tensor. The higher moments of the slip-rate distribution determine the fault plane and approximate rupture dimensions. The results show strong rupture propagation to the west with an average velocity of the instantaneous centroid of 3.6±.1 km/s. The rupture had a characteristic length of 178±46 km in the east-west direction and a characteristic duration of 48±2 s. The results are consistent with unilateral rupture on the east-west fault plane of the focal mechanism and rule out significant rupture on the north-south nodal plane.

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.

Dynamic rupture simulation of the 2017 Mw 7.8 Kaikoura (New Zealand) earthquake: Is spontaneous multi-fault rupture expected?

NASA Astrophysics Data System (ADS)

Ando, R.; Kaneko, Y.

2017-12-01

The coseismic rupture of the 2016 Kaikoura earthquake propagated over the distance of 150 km along the NE-SW striking fault system in the northern South Island of New Zealand. The analysis of In-SAR, GPS and field observations (Hamling et al., 2017) revealed that the most of the rupture occurred along the previously mapped active faults, involving more than seven major fault segments. These fault segments, mostly dipping to northwest, are distributed in a quite complex manner, manifested by fault branching and step-over structures. Back-projection rupture imaging shows that the rupture appears to jump between three sub-parallel fault segments in sequence from the south to north (Kaiser et al., 2017). The rupture seems to be terminated on the Needles fault in Cook Strait. One of the main questions is whether this multi-fault rupture can be naturally explained with the physical basis. In order to understand the conditions responsible for the complex rupture process, we conduct fully dynamic rupture simulations that account for 3-D non-planar fault geometry embedded in an elastic half-space. The fault geometry is constrained by previous In-SAR observations and geological inferences. The regional stress field is constrained by the result of stress tensor inversion based on focal mechanisms (Balfour et al., 2005). The fault is governed by a relatively simple, slip-weakening friction law. For simplicity, the frictional parameters are uniformly distributed as there is no direct estimate of them except for a shallow portion of the Kekerengu fault (Kaneko et al., 2017). Our simulations show that the rupture can indeed propagate through the complex fault system once it is nucleated at the southernmost segment. The simulated slip distribution is quite heterogeneous, reflecting the nature of non-planar fault geometry, fault branching and step-over structures. We find that optimally oriented faults exhibit larger slip, which is consistent with the slip model of Hamling et al. (2017). We conclude that the first order characteristics of this event may be interpreted by the effect of irregularity in the fault geometry.

The Effects of Fault Bends on Rupture Propagation: A Parameter Study

NASA Astrophysics Data System (ADS)

Lozos, J. C.; Oglesby, D. D.; Duan, B.; Wesnousky, S. G.

2008-12-01

Segmented faults with stepovers are ubiquitous, and occur at a variety of scales, ranging from small stepovers on the San Jacinto Fault, to the large-scale stepover on of the San Andreas Fault between Tejon Pass and San Gorgonio Pass. Because this type of fault geometry is so prevalent, understanding how rupture propagates through such systems is important for evaluating seismic hazard at different points along these faults. In the present study, we systematically investigate how far rupture will propagate through a fault with a linked (i.e., continuous fault) stepover, based on the length of the linking fault segment and the angle that connects the linking segment to adjacent segments. We conducted dynamic models of such systems using a two-dimensional finite element code (Duan and Oglesby 2007). The fault system in our models consists of three segments: two parallel 10km-long faults linked at a specified angle by a linking segment of between 500 m and 5 km. This geometry was run both as a extensional system and a compressional system. We observed several distinct rupture behaviors, with systematic differences between compressional and extensional cases. Both shear directions rupture straight through the stepover for very shallow stepover angles. In compressional systems with steeper angles, rupture may jump ahead from the stepover segment onto the far segment; whether or not rupture on this segment reaches critical patch size and slips fully is also a function of angle and stepover length. In some compressional cases, if the angle is steep enough and the stepover short enough, rupture may jump over the step entirely and propagate down the far segment without touching the linking segment. In extensional systems, rupture jumps from the nucleating segment onto the linking segment even at shallow angles, but at steeper angles, rupture propagates through without jumping. It is easier to propagate through a wider range of angles in extensional cases. In both extensional and compressional cases, for each stepover length there exists a maximum angle through which rupture can fully propagate; this maximum angle decreases asymptotically to a minimum value as the stepover length increases. We also found that a wave associated with a stopping phase coming from the far end of the fault may restart rupture and induce full propagation after a significant delay in some cases where the initial rupture terminated.

Rupture Forces among Human Blood Platelets at different Degrees of Activation

PubMed Central

Nguyen, Thi-Huong; Palankar, Raghavendra; Bui, Van-Chien; Medvedev, Nikolay; Greinacher, Andreas; Delcea, Mihaela

2016-01-01

Little is known about mechanics underlying the interaction among platelets during activation and aggregation. Although the strength of a blood thrombus has likely major biological importance, no previous study has measured directly the adhesion forces of single platelet-platelet interaction at different activation states. Here, we filled this void first, by minimizing surface mediated platelet-activation and second, by generating a strong adhesion force between a single platelet and an AFM cantilever, preventing early platelet detachment. We applied our setup to measure rupture forces between two platelets using different platelet activation states, and blockade of platelet receptors. The rupture force was found to increase proportionally to the degree of platelet activation, but reduced with blockade of specific platelet receptors. Quantification of single platelet-platelet interaction provides major perspectives for testing and improving biocompatibility of new materials; quantifying the effect of drugs on platelet function; and assessing the mechanical characteristics of acquired/inherited platelet defects. PMID:27146004

3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1  s) ground motions and sensitivity to kinematic rupture parameters

USGS Publications Warehouse

Moschetti, Morgan P.; Hartzell, Stephen; Ramirez-Guzman, Leonardo; Frankel, Arthur; Angster, Stephen J.; Stephenson, William J.

2017-01-01

We examine the variability of long‐period (T≥1  s) earthquake ground motions from 3D simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone, Utah, from a set of 96 rupture models with varying slip distributions, rupture speeds, slip velocities, and hypocenter locations. Earthquake ruptures were prescribed on a 3D fault representation that satisfies geologic constraints and maintained distinct strands for the Warm Springs and for the East Bench and Cottonwood faults. Response spectral accelerations (SA; 1.5–10 s; 5% damping) were measured, and average distance scaling was well fit by a simple functional form that depends on the near‐source intensity level SA0(T) and a corner distance Rc:SA(R,T)=SA0(T)(1+(R/Rc))−1. Period‐dependent hanging‐wall effects manifested and increased the ground motions by factors of about 2–3, though the effects appeared partially attributable to differences in shallow site response for sites on the hanging wall and footwall of the fault. Comparisons with modern ground‐motion prediction equations (GMPEs) found that the simulated ground motions were generally consistent, except within deep sedimentary basins, where simulated ground motions were greatly underpredicted. Ground‐motion variability exhibited strong lateral variations and, at some sites, exceeded the ground‐motion variability indicated by GMPEs. The effects on the ground motions of changing the values of the five kinematic rupture parameters can largely be explained by three predominant factors: distance to high‐slip subevents, dynamic stress drop, and changes in the contributions from directivity. These results emphasize the need for further characterization of the underlying distributions and covariances of the kinematic rupture parameters used in 3D ground‐motion simulations employed in probabilistic seismic‐hazard analyses.

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.

Dynamic Rupture along a Material Interface: Background, Implications, and Recent Seismological Observations

NASA Astrophysics Data System (ADS)

Ben-Zion, Y.; McGuire, J.

2003-04-01

Natural fault systems have interfaces that separate different media. There are fundamental differences between in-plane ruptures on planar faults that separate similar and dissimilar elastic solids. In a linear isotropic homogeneous solid, slip does not change the normal stress on the rupture plane. However, if the fault separates different materials in-plane slip can produce strong variations of normal stress on the fault. The interaction between slip and normal stress along a material interface can reduce dynamically the frictional strength, making material interfaces mechanically favored surfaces for rupture propagation. Analytical and numerical works (Weertman, 1980; Adams, 1995; Andrews and Ben-Zion, 1997; Ben-Zion and Andrews, 1998) have shown that rupture along a material interface occurs as a narrow wrinkle-like pulse propagating spontaneously only in one direction, that of slip in the more compliant medium. Characteristic features of the wrinkle-like pulse include: (1) Strong correlation between variations of normal stress and slip. (2) Asymmetric motion on different sides of the fault. (3) Preferred direction of rupture propagation. (4) Self-sharpening and divergent behavior with propagation distance. These characteristics can be important to a number of fundamental issues, including trapping of rupture in structures with material interfaces, the heat flow paradox, short rise-time of earthquake slip, possible existence of tensile component of rupture, and spatial distribution of seismic shaking. Rubin and Gillard (2000), Rubin (2002) and McGuire et al. (2002) presented some seismological evidence that rupture propagation along the San Andreas and other large faults is predominantly unidirectional. Features (1)-(4) are consistent with observations from lab sliding and fracture experiments (Anooshehpoor and Brune, 1999; Schallamach, 1971; Samudrala and Rosakis, 2000). Cochard and Rice (2000) performed calculations of rupture along a material interface governed by a regularized friction having a gradual response of strength to an abrupt variation of normal stress. Their calculations confirmed features (1)-(3) and showed hints of feature (4). The latter was not fully developed in their results because the calculations did not extend long enough in time. Ben-Zion and Huang (2002) simulated dynamic rupture on an interface governed by the regularized friction between a low velocity layer and a surrounding host rock. The results show that the self-sharpening and divergent behavior exists also with the regularized friction for large enough propagation distance. The simulations of Ben-Zion and Huang suggest that in fault structures having a low velocity layer, rupture initiated by failing of an asperity with size not larger than the layer width can become a self-sustaining wrinkle-like pulse. However, if the initial asperity is much larger than the layer width, the rupture will not propagate as a self-sustaining pulse (unless there is also an overall contrast across the fault). The Bear Valley section of the San Andreas Fault separates high velocity block on the SW from a low-velocity material on the NE. This contrast is expected to generate a preference for rupture to the SE and fault zone head-waves on the NE block. Using seismograms from a high density temporary array (Thurber et al., 1997), we measured differential travel-times of head-waves along with the geometrical distribution of the stations at which they arrive prior to the direct P-wave. The travel-time data and spatial distribution of events and stations associated with headwave first arrivals are compatible with the theoretical results of Ben-Zion (1989). We are now modeling waveforms to obtain high resolution image of the fault-zone structure. To test the prediction of unidirectional rupture propagation, we estimate the space-time variances of the moment-release distribution of magnitude 2.5-3.0 events using a variation of the Empirical Green's Function technique. Initial results for a few small events indicate rupture propagation in both directions. We are developing a catalog that will hopefully be large enough to provide clear results on this issue.

Source and Aftershock Analysis of a Large Deep Earthquake in the Tonga Flat Slab

NASA Astrophysics Data System (ADS)

Cai, C.; Wiens, D. A.; Warren, L. M.

2013-12-01

The 9 November 2009 (Mw 7.3) deep focus earthquake (depth = 591 km) occurred in the Tonga flat slab region, which is characterized by limited seismicity but has been imaged as a flat slab in tomographic imaging studies. In addition, this earthquake occurred immediately beneath the largest of the Fiji Islands and was well recorded by a temporary array of 16 broadband seismographs installed in Fiji and Tonga, providing an excellent opportunity to study the source mechanism of a deep earthquake in a partially aseismic flat slab region. We determine the positions of main shock hypocenter, its aftershocks and moment release subevents relative to the background seismicity using a hypocentroidal decomposition relative relocation method. We also investigate the rupture directivity by measuring the variation of rupture durations at different azimuth [e.g., Warren and Silver, 2006]. Arrival times picked from the local seismic stations together with teleseismic arrival times from the International Seismological Centre (ISC) are used for the relocation. Teleseismic waveforms are used for directivity study. Preliminary results show this entire region is relatively aseismic, with diffuse background seismicity distributed between 550-670 km. The main shock happened in a previously aseismic region, with only 1 small earthquake within 50 km during 1980-2012. 11 aftershocks large enough for good locations all occurred within the first 24 hours following the earthquake. The aftershock zone extends about 80 km from NW to SE, covering a much larger area than the mainshock rupture. The aftershock distribution does not correspond to the main shock fault plane, unlike the 1994 March 9 (Mw 7.6) Fiji-Tonga earthquake in the steeply dipping, highly seismic part of the Tonga slab. Mainshock subevent locations suggest a sub-horizontal SE-NW rupture direction. However, the directivity study shows a complicated rupture process which could not be solved with simple rupture assumption. We will present the result of this example earthquake and some other deep earthquakes at the fall meeting. Warren, L. M., and P. G. Silver (2006), Measurement of differential rupture durations as constraints on the source finiteness of deep earthquakes, J. Geophys. Res., 111, B06304, doi:10.1029/2005JB004001.

Effect of thermal cycling in a Mach 0.3 burner rig on properties and structure of directionally solidified gamma/gamma prime - delta eutectic

NASA Technical Reports Server (NTRS)

Gray, H. R.; Sanders, W. A.

1975-01-01

Tensile and stress rupture properties at 1040 C of a thermally cycled gamma/gamma prime - delta eutectic were essentially equivalent to the as-grown properties. Tensile strength and rupture life at 760 C appeared to decrease slightly by thermal cycling. Thermal cycling resulted in gamma prime coarsening and Widmanstatten delta precipitation in the gamma phase. An unidentified precipitate, presumably gamma prime, was observed within the delta phase. The eutectic alloy exhibited a high rate of oxidation-erosion weight loss during thermal cycling in the Mach 0.3 burner rig.

The 2002 Denali fault earthquake, Alaska: A large magnitude, slip-partitioned event

USGS Publications Warehouse

Eberhart-Phillips, D.; Haeussler, Peter J.; Freymueller, J.T.; Frankel, A.D.; Rubin, C.M.; Craw, P.; Ratchkovski, N.A.; Anderson, G.; Carver, G.A.; Crone, A.J.; Dawson, T.E.; Fletcher, H.; Hansen, R.; Harp, E.L.; Harris, R.A.; Hill, D.P.; Hreinsdottir, S.; Jibson, R.W.; Jones, L.M.; Kayen, R.; Keefer, D.K.; Larsen, C.F.; Moran, S.C.; Personius, S.F.; Plafker, G.; Sherrod, B.; Sieh, K.; Sitar, N.; Wallace, W.K.

2003-01-01

The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity.

Rupture process of the 2009 L'Aquila, central Italy, earthquake, from the separate and joint inversion of Strong Motion, GPS and DInSAR data.

NASA Astrophysics Data System (ADS)

Cirella, A.; Piatanesi, A.; Tinti, E.; Chini, M.; Cocco, M.

2012-04-01

In this study, we investigate the rupture history of the April 6th 2009 (Mw 6.1) L'Aquila normal faulting earthquake by using a nonlinear inversion of strong motion, GPS and DInSAR data. We use a two-stage non-linear inversion technique. During the first stage, an algorithm based on the heat-bath simulated annealing generates an ensemble of models that efficiently sample the good data-fitting regions of parameter space. In the second stage the algorithm performs a statistical analysis of the ensemble providing us the best-fitting model, the average model, the associated standard deviation and coefficient of variation. This technique, rather than simply looking at the best model, extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter. The application to the 2009 L'Aquila main-shock shows that both the separate and joint inversion solutions reveal a complex rupture process and a heterogeneous slip distribution. Slip is concentrated in two main asperities: a smaller shallow patch of slip located up-dip from the hypocenter and a second deeper and larger asperity located southeastward along strike direction. The key feature of the source process emerging from our inverted models concerns the rupture history, which is characterized by two distinct stages. The first stage begins with rupture initiation and with a modest moment release lasting nearly 0.9 seconds, which is followed by a sharp increase in slip velocity and rupture speed located 2 km up-dip from the nucleation. During this first stage the rupture front propagated up-dip from the hypocenter at relatively high (˜ 4.0 km/s), but still sub-shear, rupture velocity. The second stage starts nearly 2 seconds after nucleation and it is characterized by the along strike rupture propagation. The largest and deeper asperity fails during this stage of the rupture process. The rupture velocity is larger in the up-dip than in the along-strike direction. The up-dip and along-strike rupture propagation are separated in time and associated with a Mode II and a Mode III crack, respectively. Our results show that the 2009 L'Aquila earthquake featured a very complex rupture, with strong spatial and temporal heterogeneities suggesting a strong frictional and/or structural control of the rupture process.

Impact of Aneurysm Projection on Intraoperative Complications During Surgical Clipping of Ruptured Posterior Communicating Artery Aneurysms.

PubMed

Fukuda, Hitoshi; Hayashi, Kosuke; Yoshino, Kumiko; Koyama, Takashi; Lo, Benjamin; Kurosaki, Yoshitaka; Yamagata, Sen

2016-03-01

Surgical clipping of ruptured posterior communicating artery (PCoA) aneurysms is a well-established procedure to date. However, preoperative factors associated with procedure-related risk require further elucidation. To investigate the impact of the direction of aneurysm projection on the incidence of procedure-related complications during surgical clipping of ruptured PCoA aneurysms. A total of 65 patients with ruptured PCoA aneurysms who underwent surgical clipping were retrospectively analyzed from a single-center, prospective, observational cohort database in this study. The aneurysms were categorized into lateral and posterior projection groups, depending on direction of the dome. Characteristics and operative findings of each projection group were identified. We also evaluated any correlation of aneurysm projection with the incidence of procedure-related complications. Patients with ruptured PCoA aneurysms with posterior projection more likely presented with good-admission-grade subarachnoid hemorrhage (P = .01, χ test) and were less to also have intracerebral hematoma (P = .01). These aneurysms were found to be associated with higher incidence of intraoperative rupture (P = .02), complex clipping with fenestrated clips (P = .02), and dense adherence to PCoA or its perforators (P = .04) by univariate analysis. Aneurysms with posterior projection were also correlated with procedure-related complications, including postoperative cerebral infarction or hematoma formation (odds ratio, 5.87; 95% confidence interval, 1.11-31.1; P = .04) by multivariable analysis. Ruptured PCoA aneurysms with posterior projection carried a higher risk of procedure-related complications of surgical clipping than those with lateral projection.

The 2014 Mihoub earthquake (Mw4.3), northern Algeria: empirical Green's function analysis of the mainshock and the largest aftershock

NASA Astrophysics Data System (ADS)

Semmane, F.; Benabdeloued, B. Y. N.; Heddar, A.; Khelif, M. F.

2017-11-01

On November 15, 2014, an Mw4.3 earthquake occurred 2 km west of Mihoub village, 60 km SE of Algiers. In this study, we retrieve the relative source-time functions of the mainshock and largest aftershock (Mw3.9) for rupture analysis using the empirical Green's function method. The two events are nearly colocated with a smaller aftershock (Mw3.5), which is treated as the empirical Green's function. Moreover, these three events have similar focal mechanisms, suggesting that deconvolution is well posed in this case. The three events were recorded by nine stations of the Algerian permanent network. We use mainly P-wave data. The focal mechanism solution shows dominant reverse faulting with a strong strike-slip component. The two nodal planes align almost E-W, dipping to the south, and NNE-SSW, dipping to the NW, respectively; the fault and auxiliary planes cannot be resolved from hypocenter locations alone because too few aftershocks were recorded by the permanent network. The results show unilateral rupture propagation to the ENE and complex rupture with multiple episodes for the mainshock. The largest aftershock shows similar behavior with slightly less pronounced directivity at some sites. The rupture directivity for the mainshock is estimated at about N66° E, and the rupture velocity is Vr = 0.66 β. The E-W nodal plane of the best-fit focal mechanism is the preferred fault plane because it best agrees with the directivity direction and is consistent with the E-W faulting that dominates in the region.

Rupture Propagation Imaging of Fluid Induced Events at the Basel EGS Project

NASA Astrophysics Data System (ADS)

Folesky, Jonas; Kummerow, Jörn; Shapiro, Serge A.

2014-05-01

The analysis of rupture properties using rupture propagation imaging techniques is a fast developing field of research in global seismology. Usually rupture fronts of large to megathrust earthquakes are subject of recent studies, like e.g. the 2004 Sumatra-Andaman earthquake or the 2011 Tohoku, Japan earthquake. The back projection technique is the most prominent technique in this field. Here the seismograms recorded at an array or at a seismic network are back shifted to a grid of possible source locations via a special stacking procedure. This can provide information on the energy release and energy distribution of the rupture which then can be used to find estimates of event properties like location, rupture direction, rupture speed or length. The procedure is fast and direct and it only relies on a reasonable velocity model. Thus it is a good way to rapidly estimate the rupture properties and it can be used to confirm independently achieved event information. We adopted the back projection technique and put it in a microseismic context. We demonstrated its usage for multiple synthetic ruptures within a reservoir model of microseismic scale in earlier works. Our motivation hereby is the occurrence of relatively large, induced seismic events at a number of stimulated geothermal reservoirs or waste disposal sites, having magnitudes ML ≥ 3.4 and yielding rupture lengths of several hundred meters. We use the configuration of the seismic network and reservoir properties of the Basel Geothermal Site to build a synthetic model of a rupture by modeling the wave field of multiple spatio-temporal separated single sources using Finite-Difference modeling. The focus of this work is the application of the Back Projection technique and the demonstration of its feasibility to retrieve the rupture properties of real fluid induced events. We take four microseismic events with magnitudes from ML 3.1 to 3.4 and reconstruct source parameters like location, orientation and length. By comparison with our synthetic results as well as independent localization studies and source mechanism studies in this area we can show, that the obtained results are reasonable and that the application of back projection imaging is not only possible for microseismic datasets of respective quality, but that it provides important additional insights in the rupture process.

Multiple tendon ruptures of unknown etiology.

PubMed

Axibal, Derek P; Anderson, John G

2013-10-01

Tendon ruptures are common findings in foot and ankle practice. The etiology of tendon ruptures tends to be multifactorial-usually due to a combination of trauma, effects of systemic diseases, adverse effects of medications, and obesity. We present an unusual case of right Achilles tendinitis, left Achilles tendon rupture, bilateral peroneus longus tendon rupture, and left peroneus brevis tendon rupture of unknown etiology. This case report highlights the need for research for other possible, lesser known etiologies of tendon pathology. Therapeutic, Level IV, Case Study.

The influence of atmospheric pressure on aortic aneurysm rupture--is the diameter of the aneurysm important?

PubMed

Urbanek, Tomasz; Juśko, Maciej; Niewiem, Alfred; Kuczmik, Wacław; Ziaja, Damian; Ziaja, Krzysztof

2015-01-01

The rate of aortic aneurysm rupture correlates with the aneurysm's diameter, and a higher rate of rupture is observed in patients with larger aneurysms. According to the literature, contradictory results concerning the relationship between atmospheric pressure and aneurysm size have been reported. In this paper, we assessed the influence of changes in atmospheric pressure on abdominal aneurysm ruptures in relationship to the aneurysm's size. The records of 223 patients with ruptured abdominal aneurysms were evaluated. All of the patients had been admitted to the department in the period 1997-2007 from the Silesia region. The atmospheric pressures on the day of the rupture and on the days both before the rupture and between the rupture events were compared. The size of the aneurysm was also considered in the analysis. There were no statistically significant differences in pressure between the days of rupture and the remainder of the days within an analysed period. The highest frequency of the admission of patients with a ruptured aortic aneurysm was observed during periods of winter and spring, when the highest mean values of atmospheric pressure were observed; however, this observation was not statistically confirmed. A statistically non-significant trend towards the higher rupture of large aneurysms (> 7 cm) was observed in the cases where the pressure increased between the day before the rupture and the day of the rupture. This trend was particularly pronounced in patients suffering from hypertension (p = 0.1). The results of this study do not support the hypothesis that there is a direct link between atmospheric pressure values and abdominal aortic aneurysm ruptures.

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.

Persistency of rupture directivity in moderate-magnitude earthquakes in Italy: Implications for seismic hazard

NASA Astrophysics Data System (ADS)

Rovelli, A.; Calderoni, G.

2012-12-01

A simple method based on the EGF deconvolution in the frequency domain is applied to detect the occurrence of unilateral ruptures in recent damaging earthquakes in Italy. The spectral ratio between event pairs with different magnitudes at individual stations shows large azimuthal variations above corner frequency when the target event is affected by source directivity and the EGF is not or vice versa. The analysis is applied to seismograms and accelerograms recorded during the seismic sequence following the 20 May 2012, Mw 5.6 main shock in Emilia, northern Italy, the 6 April 2009, Mw 6.1 earthquake of L'Aquila, central Italy, and the 26 September 1997, Mw 5.7 and 6.0 shocks in Umbria-Marche, central Italy. Events of each seismic sequence are selected as having consistent focal mechanisms, and the station selection obeys to the constraint of a similar source-to-receiver path for the event pairs. The analyzed data set of L'Aquila consists of 962 broad-band seismograms relative to 69 normal-faulting earthquakes (3.3 ≤ MW ≤ 6.1, according to Herrmann et al., 2011), stations are selected in the distance range 100 to 250 km to minimize differences in propagation paths. The seismogram analysis reveals that a strong along-strike (toward SE) source directivity characterized all of the three Mw > 5.0 shocks. Source directivity was also persistent up to the smallest magnitudes: 65% of earthquakes under study showed evidence of directivity toward SE whereas only one (Mw 3.7) event showed directivity in the opposite direction. Also the Mw 5.6 main shock of the 20 May 2012 in Emilia result in large azimuthal spectral variations indicating unilateral rupture propagation toward SE. According to the reconstructed geometry of the trust-fault plane, the inferred directivity direction suggests top-down rupture propagation. The analysis over the Emilia aftershock sequence is in progress. The third seismic sequence, dated 1997-1998, occurred in the northern Apennines and, similarly to L'Aquila faults, was characterized by normal-faulting earthquakes with strike substantially parallel to the Apennine trend. Although the amount of data is not as abundant as for the most recent earthquakes, the available data were already object of previous studies indicating unilateral rupture propagation in several of the strongest (5.5 < Mw < 6.0) shocks. We show that the effect of directivity is particularly significant in intermontane basins where long-period (T > 1 sec) ground motions are amplified by soft sediments and the combination of local amplification with source directivity causes exceedance of spectral ordinates at those periods up to more than 2 standard deviations from the expected values of commonly used GMPEs for soft sites. These results arise a concern in terms of seismic hazard because source directivity is found to be recurrent feature in the Apennines. Moreover, the predominant fault strike and intermontane basins are both aligned along the Apennine chain offering a condition potentially favorable to extra-amplifications at periods relevant to seismic risk.

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.

Chorioretinal neovascular membranes complicating contusional eye injuries with indirect choroidal ruptures.

PubMed Central

Wood, C M; Richardson, J

1990-01-01

Chorioretinal neovascular membranes are a recognised but rare cause of late visual loss in eyes suffering contusional injuries. A series of eight cases is presented all with indirect choroidal ruptures involving the perifoveal region. Two main patterns of 'at risk' rupture were noted: a temporally situated rupture passing almost directly through the fovea, and a rupture which curves inferior or superior to the optic disc stopping just short of the fovea. In six of eight cases there was only a partial thickness rupture of the choroid. These neovascular membranes may present at any time after the original injury, either early (within six months of the injury), which could be related to persistence of the normal reparative neovascular response, or late (at least one year after the injury), which are more likely to have resulted from a secondary breakdown of the outer blood-retina barrier. Images PMID:1690025

Rupture behaviors of the 2010 Jiashian and 2016 Meinong Earthquakes: Implication for interaction of two asperities on the Chishan Transfer Fault Zone in SW Taiwan.

NASA Astrophysics Data System (ADS)

Jian, P. R.; Hung, S. H.; Chen, Y. L.; Meng, L.; Tseng, T. L.

2017-12-01

After about 45 years of seismic quiescence, southwest Taiwan was imperiled by two strong earthquakes, the 2010 Mw 6.2 Jiashian and deadly 2016 Mw 6.4 Meinong earthquakes in the last decade. The focal mechanisms and their aftershock distributions imply that both events occurred on NW-SE striking, shallow-dipping fault planes but at different depths of 21 and 16 km, respectively. Here we present the MUSIC back projection images using high-frequency P- and sP-waves recorded in the European and Australian seismic networks, the directivity analysis using global teleseismic P waves and relocated aftershocks to characterize the rupture behaviors of the two mainshocks and explore the potential connection between them. The results for the Meinong event indicate a unilateral, subhorizontal rupture propagating NW-ward 17 km and lasting for 6-7 s [Jian et al., 2017]. For the Jiashian event, the rupture initiated at a greater depth of 21 km and then propagated both NW-ward and up-dip ( 16o) on the fault plane, with a shorter rupture length of 10 km and duration of 4-5 s. The up-dip propagation is corroborated by the 3-D directivity analysis that leads to the widths of P-wave pulses increasing linearly with the directivity parameter. Moreover, relocation of aftershocks reveals that the Jiashian sequence is confined in a NW-SE elongated zone extending 15 km and 5 km shallower than the hypocenter. The Meinong aftershock sequence shows three clusters: one surrounding the mainshock hypocenter, another one distributed northwestern and deeper (>20 km) off the rupture plane beneath Tainan, and the other distant shallow-focus one (<10 km) beneath the southern Central Mountain Range. As evidenced by similar focal mechanism, rupture behaviors, as well as the spatial configuration of the mainshock rupture zones and aftershock distributions, we attribute the Jiashian and Meinong earthquakes to two asperities on a buried oblique fault that has been reactivated recently, the NW-SE striking Chishan Transfer Fault Zone as a likely candidate rupture plane. In 2010, the Jiasian earthquake initiated at the deeper NE asperity and propagated NW-ward and up-dip. Six years later, the stronger shallower asperity responsible for the Meinong event was statically triggered, which consequently caused the ruinous destruction in SW Taiwan.

Shear rupture of a directionally solidified eutectic gamma/gamma prime - alpha (Mo) alloy

NASA Technical Reports Server (NTRS)

Harf, F. H.

1978-01-01

Directionally solidified Mo alloys are evaluated to determine the shear rupture strength and to possibly improve it by microstructural and heat treatment variations. Bars of the alloy containing nominally 5.7% Al and 33.5% Mo by weight with balance Ni were directionally solidified at rates between 10 and 100 mm per hour in furnaces with thermal gradients at the liquid-solid interface of 250 or 100 C per cm. A limited number of longitudinal shear rupture tests were conducted at 760 C and 207 MPa in the as - solidified and in several heat treated conditions. It is shown that shear rupture failures are partly transgranular and that resistance to failure is prompted by good fiber alignment and a matrix structure consisting mainly of gamma prime. Well aligned as - solidified specimens sustained the shear stress for an average of 81 hours. A simulated coating heat treatment appeared to increase the transformation of gamma to gamma prime and raised the average shear life of aligned specimens to 111 hours. However, heat treatments at 1245 C and especially at 1190 C appeared to be detrimental by causing partial solutioning of the gamma prime, and reducing lives to 47 and 10 hours, respectively.

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.

Study of clad ballooning and rupture behaviour of Indian PHWR fuel pins under transient heating condition in steam environment

NASA Astrophysics Data System (ADS)

Sawarn, Tapan K.; Banerjee, Suparna; Sheelvantra, Smita S.; Singh, J. L.; Bhasin, Vivek

2017-11-01

This paper presents the results of the investigation on the deformation and rupture characteristics of Indian pressurized heavy water reactor (IPHWR) fuel pins under simulated loss of coolant accident (LOCA) condition in steam environment. Transient heating experiments were carried out on single fuel pin internally pressurized with argon gas in the range 3-70 bar. Effect of internal pressure on burst temperature, influence of burst temperature on the circumferential strain and rupture opening area were also studied. Two circumferential strain maxima at the burst temperatures of 740 & ∼979 °C and a minimum at the burst temperature of ∼868 °C were observed. It was found that oxidation had considerable effect on the burst behavior. Test data were used to derive a direct empirical correlation for burst stress exclusively as a function of temperature. The ballooning and rupture behaviours in steam and argon environments have been compared. Experimental data were examined against various correlations using Erbacher equation and author's previous correlation in argon. A second burst correlation has also been developed combining the equation in argon from the previous work of the authors and an exponential factor with oxygen content as a parameter assuming the burst stress to be a function of both temperature and oxygen concentration. The burst temperatures predicted by this empirical correlation are in good agreement with the test data.

Acute Iliac Artery Rupture: Endovascular Treatment

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

Chatziioannou, A.; Mourikis, D.; Katsimilis, J.

The authors present 7 patients who suffered iliac artery rupture over a 2 year period. In 5 patients, the rupture was iatrogenic: 4 cases were secondary to balloon angioplasty for iliac artery stenosis and 1 occurred during coronary angioplasty. In the last 2 patients, the rupture was secondary to iliac artery mycotic aneurysm. Direct placement of a stent-graft was performed in all cases, which was dilated until extravasation was controlled. Placement of the stent-graft was successful in all the cases, without any complications. The techniques used, results, and mid-term follow-up are presented. In conclusion, endovascular placement of a stent-graft ismore » a quick, minimally invasive, efficient, and safe method for emergency treatment of acute iliac artery rupture, with satisfactory short- and mid-term results.« less

Distributed Seismic Moment Fault Model, Spectral Characteristics and Radiation Patterns

NASA Astrophysics Data System (ADS)

Shani-Kadmiel, Shahar; Tsesarsky, Michael; Gvirtzman, Zohar

2014-05-01

We implement a Distributed Seismic Moment (DSM) fault model, a physics-based representation of an earthquake source based on a skewed-Gaussian slip distribution over an elliptical rupture patch, for the purpose of forward modeling of seismic-wave propagation in 3-D heterogeneous medium. The elliptical rupture patch is described by 13 parameters: location (3), dimensions of the patch (2), patch orientation (1), focal mechanism (3), nucleation point (2), peak slip (1), rupture velocity (1). A node based second order finite difference approach is used to solve the seismic-wave equations in displacement formulation (WPP, Nilsson et al., 2007). Results of our DSM fault model are compared with three commonly used fault models: Point Source Model (PSM), Haskell's fault Model (HM), and HM with Radial (HMR) rupture propagation. Spectral features of the waveforms and radiation patterns from these four models are investigated. The DSM fault model best incorporates the simplicity and symmetry of the PSM with the directivity effects of the HMR while satisfying the physical requirements, i.e., smooth transition from peak slip at the nucleation point to zero at the rupture patch border. The implementation of the DSM in seismic-wave propagation forward models comes at negligible computational cost. Reference: Nilsson, S., Petersson, N. A., Sjogreen, B., and Kreiss, H.-O. (2007). Stable Difference Approximations for the Elastic Wave Equation in Second Order Formulation. SIAM Journal on Numerical Analysis, 45(5), 1902-1936.

Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

NASA Technical Reports Server (NTRS)

Howson, T. E.; Tien, J. K.; Stulga, J. E.

1980-01-01

The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

Bimodal collagen fibril diameter distributions direct age-related variations in tendon resilience and resistance to rupture

PubMed Central

Holmes, D. F.; Lu, Y.; Purslow, P. P.; Kadler, K. E.; Bechet, D.; Wess, T. J.

2012-01-01

Scaling relationships have been formulated to investigate the influence of collagen fibril diameter (D) on age-related variations in the strain energy density of tendon. Transmission electron microscopy was used to quantify D in tail tendon from 1.7- to 35.3-mo-old (C57BL/6) male mice. Frequency histograms of D for all age groups were modeled as two normally distributed subpopulations with smaller (DD1) and larger (DD2) mean Ds, respectively. Both DD1 and DD2 increase from 1.6 to 4.0 mo but decrease thereafter. From tensile tests to rupture, two strain energy densities were calculated: 1) uE [from initial loading until the yield stress (σY)], which contributes primarily to tendon resilience, and 2) uF [from σY through the maximum stress (σU) until rupture], which relates primarily to resistance of the tendons to rupture. As measured by the normalized strain energy densities uE/σY and uF/σU, both the resilience and resistance to rupture increase with increasing age and peak at 23.0 and 4.0 mo, respectively, before decreasing thereafter. Multiple regression analysis reveals that increases in uE/σY (resilience energy) are associated with decreases in DD1 and increases in DD2, whereas uF/σU (rupture energy) is associated with increases in DD1 alone. These findings support a model where age-related variations in tendon resilience and resistance to rupture can be directed by subtle changes in the bimodal distribution of Ds. PMID:22837169

A fault is born: The Landers-Mojave earthquake line

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

Nur, A.; Ron, H.

1993-04-01

The epicenter and the southern portion of the 1992 Landers earthquake fell on an approximately N-S earthquake line, defined by both epicentral locations and by the rupture directions of four previous M>5 earthquakes in the Mojave: The 1947 Manix; 1975 Galway Lake; 1979 Homestead Valley: and 1992 Joshua Tree events. Another M 5.2 earthquake epicenter in 1965 fell on this line where it intersects the Calico fault. In contrast, the northern part of the Landers rupture followed the NW-SE trending Camp Rock and parallel faults, exhibiting an apparently unusual rupture kink. The block tectonic model (Ron et al., 1984) combiningmore » fault kinematic and mechanics, explains both the alignment of the events, and their ruptures (Nur et al., 1986, 1989), as well as the Landers kink (Nur et al., 1992). Accordingly, the now NW oriented faults have rotated into their present direction away from the direction of maximum shortening, close to becoming locked, whereas a new fault set, optimally oriented relative to the direction of shortening, is developing to accommodate current crustal deformation. The Mojave-Landers line may thus be a new fault in formation. During the transition of faulting from the old, well developed and wak but poorly oriented faults to the strong, but favorably oriented new ones, both can slip simultaneously, giving rise to kinks such as Landers.« less

Kinematic Rupture Process of the 2015 Gorkha (Nepal) Earthquake Sequence from Joint Inversion of Teleseismic, hr-GPS, Strong-Ground Motion, InSAR interferograms and pixel offsets

NASA Astrophysics Data System (ADS)

Yue, H.; Simons, M.; Jiang, J.; Fielding, E. J.; Owen, S. E.; Moore, A. W.; Riel, B. V.; Polet, J.; Duputel, Z.; Samsonov, S. V.; Avouac, J. P.

2015-12-01

The April 2015 Gorkha, Nepal (Mw 7.8) earthquake ruptured the front of Himalaya thrust belt, causing more than 9,000 fatalities. 17 days after the main event, a large aftershock (Mw 7.2) ruptured to down-dip and east of the main rupture area. To investigate the kinematic rupture process of this earthquake sequence, we explored linear and non-linear inversion techniques using a variety of datasets including teleseismic, high rate and conventional GPS, InSAR interferograms and pixel-offsets. InSAR interferograms from ALOS-2, RADARSAT-2 and Sentinel-1a satellites are used in the joint inversion. The main event is characterized by unilateral rupture extending along strike approximately 70 km to the southeast and 40 km along dip direction. The rupture velocity is well resolved to be lie between 2.8 and 3.0 km/s, which is consistent with back-projection results. An emergent initial phase is observed in teleseismic body wave records, which is consistent with a narrow area of rupture initiation near the hypocenter. The rupture mode of the main event is pulse like. The aftershock ruptured down-dip to the northeast of the main event rupture area. The aftershock rupture area is compact and contained within 40 km of its hypocenter. In contrast to the main event, teleseismic body wave records of the aftershock suggest an abrupt initial phase, which is consistent with a crack like rupture mode. The locations of most of the aftershocks (small and large) surround the rupture area of the main shock with little, if any, spatial overlap.

Global variations of large megathrust earthquake rupture characteristics

PubMed Central

Kanamori, Hiroo

2018-01-01

Despite the surge of great earthquakes along subduction zones over the last decade and advances in observations and analysis techniques, it remains unclear whether earthquake complexity is primarily controlled by persistent fault properties or by dynamics of the failure process. We introduce the radiated energy enhancement factor (REEF), given by the ratio of an event’s directly measured radiated energy to the calculated minimum radiated energy for a source with the same seismic moment and duration, to quantify the rupture complexity. The REEF measurements for 119 large [moment magnitude (Mw) 7.0 to 9.2] megathrust earthquakes distributed globally show marked systematic regional patterns, suggesting that the rupture complexity is strongly influenced by persistent geological factors. We characterize this as the existence of smooth and rough rupture patches with varying interpatch separation, along with failure dynamics producing triggering interactions that augment the regional influences on large events. We present an improved asperity scenario incorporating both effects and categorize global subduction zones and great earthquakes based on their REEF values and slip patterns. Giant earthquakes rupturing over several hundred kilometers can occur in regions with low-REEF patches and small interpatch spacing, such as for the 1960 Chile, 1964 Alaska, and 2011 Tohoku earthquakes, or in regions with high-REEF patches and large interpatch spacing as in the case for the 2004 Sumatra and 1906 Ecuador-Colombia earthquakes. Thus, combining seismic magnitude Mw and REEF, we provide a quantitative framework to better represent the span of rupture characteristics of great earthquakes and to understand global seismicity. PMID:29750186

The effect of electron beam welding on the creep rupture properties of a Nb-Zr-C alloy

NASA Technical Reports Server (NTRS)

Moore, T. J.; Titran, R. H.; Grobstein, T. L.

1986-01-01

Creep rupture tests of electron beam welded PWC-11 sheet were conducted at 1350 K. Full penetration, single pass welds were oriented transverse to the testing direction in 1 mm thick sheet. With this orientation, stress was imposed equally on the base metal, weld metal, and heat-affected zone. Tests were conducted in both the postweld annealed and aged conditions. Unwelded specimens with similar heat treatments were tested for comparative purposes. It was found that the weld region is stronger than the base metal for both the annealed and aged conditions and that the PWC-11 material is stronger in the annealed condition than in the aged condition.

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.

Simultaneous uterine and urinary bladder rupture in an otherwise successful vaginal birth after cesarean delivery.

PubMed

Ho, Szu-Ying; Chang, Shuenn-Dhy; Liang, Ching-Chung

2010-12-01

Uterine rupture is the primary concern when a patient chooses a trial of labor after a cesarean section. Bladder rupture accompanied by uterine rupture should be taken into consideration if gross hematuria occurs. We report the case of a patient with uterine rupture during a trial of labor after cesarean delivery. She had a normal course of labor and no classic signs of uterine rupture. However, gross hematuria was noted after repair of the episiotomy. The patient began to complain of progressive abdominal pain, gross hematuria and oliguria. Cystoscopy revealed a direct communication between the bladder and the uterus. When opening the bladder peritoneum, rupture sites over the anterior uterus and posterior wall of the bladder were noted. Following primary repair of both wounds, a Foley catheter was left in place for 12 days. The patient had achieved a full recovery by the 2-year follow-up examination. Bladder injury and uterine rupture can occur at any time during labor. Gross hematuria immediately after delivery is the most common presentation. Cystoscopy is a good tool to identify the severity of bladder injury. Copyright © 2010 Elsevier. Published by Elsevier B.V. All rights reserved.

Strain rate effect on fault slip and rupture evolution: Insight from meter-scale rock friction experiments

NASA Astrophysics Data System (ADS)

Xu, Shiqing; Fukuyama, Eiichi; Yamashita, Futoshi; Mizoguchi, Kazuo; Takizawa, Shigeru; Kawakata, Hironori

2018-05-01

We conduct meter-scale rock friction experiments to study strain rate effect on fault slip and rupture evolution. Two rock samples made of Indian metagabbro, with a nominal contact dimension of 1.5 m long and 0.1 m wide, are juxtaposed and loaded in a direct shear configuration to simulate the fault motion. A series of experimental tests, under constant loading rates ranging from 0.01 mm/s to 1 mm/s and under a fixed normal stress of 6.7 MPa, are performed to simulate conditions with changing strain rates. Load cells and displacement transducers are utilized to examine the macroscopic fault behavior, while high-density arrays of strain gauges close to the fault are used to investigate the local fault behavior. The observations show that the macroscopic peak strength, strength drop, and the rate of strength drop can increase with increasing loading rate. At the local scale, the observations reveal that slow loading rates favor generation of characteristic ruptures that always nucleate in the form of slow slip at about the same location. In contrast, fast loading rates can promote very abrupt rupture nucleation and along-strike scatter of hypocenter locations. At a given propagation distance, rupture speed tends to increase with increasing loading rate. We propose that a strain-rate-dependent fault fragmentation process can enhance the efficiency of fault healing during the stick period, which together with healing time controls the recovery of fault strength. In addition, a strain-rate-dependent weakening mechanism can be activated during the slip period, which together with strain energy selects the modes of fault slip and rupture propagation. The results help to understand the spectrum of fault slip and rock deformation modes in nature, and emphasize the role of heterogeneity in tuning fault behavior under different strain rates.

Endovascular or open repair strategy for ruptured abdominal aortic aneurysm: 30 day outcomes from IMPROVE randomised trial.

PubMed

Powell, Janet T; Sweeting, Michael J; Thompson, Matthew M; Ashleigh, Ray; Bell, Rachel; Gomes, Manuel; Greenhalgh, Roger M; Grieve, Richard; Heatley, Francine; Hinchliffe, Robert J; Thompson, Simon G; Ulug, Pinar

2014-01-13

To assess whether a strategy of endovascular repair (if aortic morphology is suitable, open repair if not) versus open repair reduces early mortality for patients with suspected ruptured abdominal aortic aneurysm. Randomised controlled trial. 30 vascular centres (29 UK, 1 Canadian), 2009-13. 613 eligible patients (480 men) with a clinical diagnosis of ruptured aneurysm. 316 patients were randomised to the endovascular strategy (275 confirmed ruptures, 174 anatomically suitable for endovascular repair) and 297 to open repair (261 confirmed ruptures). 30 day mortality, with 24 hour and in-hospital mortality, costs, and time and place of discharge as secondary outcomes. 30 day mortality was 35.4% (112/316) in the endovascular strategy group and 37.4% (111/297) in the open repair group: odds ratio 0.92 (95% confidence interval 0.66 to 1.28; P=0.62); odds ratio after adjustment for age, sex, and Hardman index 0.94 (0.67 to 1.33). Women may benefit more than men (interaction test P=0.02) from the endovascular strategy: odds ratio 0.44 (0.22 to 0.91) versus 1.18 (0.80 to 1.75). 30 day mortality for patients with confirmed rupture was 36.4% (100/275) in the endovascular strategy group and 40.6% (106/261) in the open repair group (P=0.31). More patients in the endovascular strategy than in the open repair group were discharged directly to home (189/201 (94%) v 141/183 (77%); P<0.001). Average 30 day costs were similar between the randomised groups, with an incremental cost saving for the endovascular strategy versus open repair of £1186 (€1420; $1939) (95% confidence interval -£625 to £2997). A strategy of endovascular repair was not associated with significant reduction in either 30 day mortality or cost. Longer term cost effectiveness evaluations are needed to assess the full effects of the endovascular strategy in both men and women. Current Controlled Trials ISRCTN48334791.

Decay of S‐wave amplitudes with distance for earthquakes in the Charlevoix, Quebec, area: Effects of radiation pattern and directivity

USGS Publications Warehouse

Frankel, Arthur

2015-01-01

The decay of the Fourier spectral amplitudes of S waves over distances of 10–80 km near Charlevoix, Quebec, was determined using waveforms from seven earthquakes with MN 3.3–5.4. The S‐wave spectral amplitudes were corrected for site response and source amplitude by normalizing the coda‐wave spectrum at a fixed time after the origin time. The amplitude decay with distance was found to be less steep as the frequency increases from 1 to 14, contrary to what would be expected from anelastic and scattering attenuation for a point source with an isotropic radiation pattern. The decay at 14 Hz indicates that the geometrical spreading at distances less than 80 km is less steep than R−1.05. The steeper distance decay of the low‐frequency spectrum appears to be an artifact of the radiation pattern and rupture directivity, which affect the low‐frequency amplitude more than the high frequency. Synthetic seismograms were made for a horizontally layered crust for the Mw 4.6 Rivière du Loup earthquake and an Mw 3.3 event. The decay with distance of the 1 Hz spectral amplitudes of the synthetics is similar to that observed for the Rivière du Loup earthquake, indicating that radiation pattern and rupture directivity are important factors in determining the attenuation with distance at 1 Hz. For the Mw 3.3 earthquake, the distance decay of the 1 Hz spectral amplitudes was found to be sensitive to the focal mechanism. This study demonstrates that estimates of geometrical spreading made using 1 Hz amplitudes can be contaminated by radiation pattern and directivity effects and may not be applicable for constructing ground‐motion prediction equations for sources with other focal mechanisms and rupture behavior.

Indirect choroidal ruptures: aetiological factors, patterns of ocular damage, and final visual outcome.

PubMed Central

Wood, C M; Richardson, J

1990-01-01

Indirect choroidal ruptures result from blunt ocular trauma and have a pathognomonic fundal appearance. We analysed a group of 30 patients with indirect choroidal ruptures with specific reference to the circumstances of the injury, the pattern of ocular damage, the cause of any visual loss, and the final visual outcome. Using this analysis we deduce a pathogenetic explanation for the characteristic fundus signs in patients with indirect choroidal ruptures. The majority of cases were young males injured during sport or by an assault, a minority were injured at work. Diffuse nonfocal impact injuries due to punches were associated with ruptures concentric with and adjacent to the optic disc. Focal impact injuries, due to projectiles, showed more extensive ocular damage. Seventeen of 30 patients regained 6/12 vision after injury. Injuries due to projectiles and temporally situated ruptures were associated with a poorer visual outcome than others. Macular damage was the commonest cause of visual loss, principally due to pigmentary maculopathy, traumatic inner retinal damage, and choroidal neovascular membranes rather than direct focal damage by the rupture. Images PMID:2337545

75 FR 26883 - Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 170 and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-13

... slat actuator structural failure (rupture) and its adjacent actuator torque limiter failing high... outboard slat actuator structural failure (rupture) and its adjacent actuator torque limiter failing high... requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in...

78 FR 64419 - Airworthiness Directives; Pratt & Whitney Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-29

... Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking... turbofan engines. This proposed AD was prompted by a rupture of the diffuser-to-high-pressure turbine (HPT... turbofan engines. (d) Unsafe Condition This AD was prompted by a rupture of the diffuser-to-high- pressure...

Percutaneous Repair Technique for Acute Achilles Tendon Rupture with Assistance of Kirschner Wire.

PubMed

He, Ze-yang; Chai, Ming-xiang; Liu, Yue-ju; Zhang, Xiao-ran; Zhang, Tao; Song, Lian-xin; Ren, Zhi-xin; Wu, Xi-rui

2015-11-01

The aim of this study is to introduce a self-designed, minimally invasive technique for repairing an acute Achilles tendon rupture percutaneously. Comparing with the traditional open repair, the new technique provides obvious advantages of minimized operation-related lesions, fewer wound complications as well as a higher healing rate. However, a percutaneous technique without direct vision may be criticized by its insufficient anastomosis of Achilles tendon and may also lead to the lengthening of the Achilles tendon and a reduction in the strength of the gastrocnemius. To address the potential problems, we have improved our technique using a percutaneous Kirschner wire leverage process before suturing, which can effectively recover the length of the Achilles tendon and ensure the broken ends are in tight contact. With this improvement in technique, we have great confidence that it will become the treatment of choice for acute Achilles tendon ruptures. © 2015 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

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.

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.

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.

A Directionally Solidified Iron-chromium-aluminum-tantalum Carbide Eutectic Alloy

NASA Technical Reports Server (NTRS)

Harf, F. H.

1977-01-01

A eutectic alloy, Fe-13.6CR-3.7Al+9TaC, was directionally solidified in a high gradient furnace, producing a microstructure of alined TaC fibers in an oxidation resistant alpha-iron matrix. Tensile and stress rupture properties, thermal cycling resistance, and microstructures were evaluated. The alloy displays at 1000 C an ultimate tensile strength of 58 MPa and a 100-hour rupture life at a stress of 21 MPa. Thermal cycling to 1100 C induces faceting in the TaC fibers.

Low-cost directionally-solidified turbine blades, volume 1

NASA Technical Reports Server (NTRS)

Sink, L. W.; Hoppin, G. S., III; Fujii, M.

1979-01-01

A low cost process of manufacturing high stress rupture strength directionally-solidified high pressure turbine blades was successfully developed for the TFE731-3 Turbofan Engine. The basic processing parameters were established using MAR-M 247 and employing the exothermic directional-solidification process in trial castings of turbine blades. Nickel-based alloys were evaluated as directionally-solidified cast blades. A new turbine blade, disk, and associated components were then designed using previously determined material properties. Engine tests were run and the results were analyzed and compared to the originally established goals. The results showed that the stress rupture strength of exothermically heated, directionally-solidified MAR-M 247 turbine blades exceeded program objectives and that the performance and cost reduction goals were achieved.

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.

Uncertainty Analyses for Back Projection Methods

NASA Astrophysics Data System (ADS)

Zeng, H.; Wei, S.; Wu, W.

2017-12-01

So far few comprehensive error analyses for back projection methods have been conducted, although it is evident that high frequency seismic waves can be easily affected by earthquake depth, focal mechanisms and the Earth's 3D structures. Here we perform 1D and 3D synthetic tests for two back projection methods, MUltiple SIgnal Classification (MUSIC) (Meng et al., 2011) and Compressive Sensing (CS) (Yao et al., 2011). We generate synthetics for both point sources and finite rupture sources with different depths, focal mechanisms, as well as 1D and 3D structures in the source region. The 3D synthetics are generated through a hybrid scheme of Direct Solution Method and Spectral Element Method. Then we back project the synthetic data using MUSIC and CS. The synthetic tests show that the depth phases can be back projected as artificial sources both in space and time. For instance, for a source depth of 10km, back projection gives a strong signal 8km away from the true source. Such bias increases with depth, e.g., the error of horizontal location could be larger than 20km for a depth of 40km. If the array is located around the nodal direction of direct P-waves the teleseismic P-waves are dominated by the depth phases. Therefore, back projections are actually imaging the reflection points of depth phases more than the rupture front. Besides depth phases, the strong and long lasted coda waves due to 3D effects near trench can lead to additional complexities tested here. The strength contrast of different frequency contents in the rupture models also produces some variations to the back projection results. In the synthetic tests, MUSIC and CS derive consistent results. While MUSIC is more computationally efficient, CS works better for sparse arrays. In summary, our analyses indicate that the impact of various factors mentioned above should be taken into consideration when interpreting back projection images, before we can use them to infer the earthquake rupture physics.

Dynamic Rupture Simulations of 11 March 2011 Tohoku Earthquake

NASA Astrophysics Data System (ADS)

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

2012-12-01

There is strong observational evidence that the 11 March 2011 Tohoku earthquake rupture reached the seafloor. This was unexpected because the shallow portion of the plate interface is believed to be frictionally stable and thus not capable of sustaining coseismic rupture. In order to explore this seeming inconsistency we have developed a two-dimensional dynamic rupture model of the Tohoku earthquake. The model uses a complex fault, seafloor, and material interface structure as derived from seismic surveys. We use a rate-and-state friction model with steady state shear strength depending logarithmically on slip velocity, i.e., there is no dynamic weakening in the model. The frictional parameters are depth dependent with the shallowest portions of the fault beneath the accretionary prism being velocity strengthening. The total normal stress on the fault is taken to be lithostatic and the pore pressure is hydrostatic until a maximum effective normal stress is reached (40 MPa in our preferred model) after which point the pore pressure follows the lithostatic gradient. We also account for poroelastic buffering of effective normal stress changes on the fault. The off-fault response is linear elastic. Using this model we find that large stress changes are dynamically transmitted to the shallowest portions of the fault by waves released by deep slip that are reflected off the seafloor. These stress changes are significant enough to drive the rupture through a velocity strengthening region that is tens of kilometers long. Rupture to the trench is therefore consistent with standard assumptions about depth-dependence of subduction zone properties, and does not require extreme dynamic weakening, shallow high stress drop asperities, or other exceptional processes. We also make direct comparisons with measured seafloor deformation and onshore 1-Hz GPS data from the Tohoku earthquake. Through these comparisons we are able to determine the sensitivity of these data to several dynamic source parameters (prestress, seismogenic depth, and the extent and frictional properties of the shallow plate interface). We find that there is a trade-off between the near-trench frictional properties and effective normal stress, particularly for onshore measurements. That is, the data can be equally well fit by either a velocity strengthening or velocity weakening near-trench fault segment, provided that compensating adjustments are also made to the maximum effective normal stress on the fault. On the other hand, the seismogenic depth is fairly well constrained from the static displacement field, independent of effective normal stress and near-trench properties. Finally, we show that a water layer (modeled as an isotropic linear acoustic material) has a negligible effect on the rupture process. That said, the inclusion of a water layer allows us to make important predictions concerning hydroacoustic signals that were observed by ocean bottom pressure sensors.

Near-Source Shaking and Dynamic Rupture in Plastic Media

NASA Astrophysics Data System (ADS)

Gabriel, A.; Mai, P. M.; Dalguer, L. A.; Ampuero, J. P.

2012-12-01

Recent well recorded earthquakes show a high degree of complexity at the source level that severely affects the resulting ground motion in near and far-field seismic data. In our study, we focus on investigating source-dominated near-field ground motion features from numerical dynamic rupture simulations in an elasto-visco-plastic bulk. Our aim is to contribute to a more direct connection from theoretical and computational results to field and seismological observations. Previous work showed that a diversity of rupture styles emerges from simulations on faults governed by velocity-and-state-dependent friction with rapid velocity-weakening at high slip rate. For instance, growing pulses lead to re-activation of slip due to gradual stress build-up near the hypocenter, as inferred in some source studies of the 2011 Tohoku-Oki earthquake. Moreover, off-fault energy dissipation implied physical limits on extreme ground motion by limiting peak slip rate and rupture velocity. We investigate characteristic features in near-field strong ground motion generated by dynamic in-plane rupture simulations. We present effects of plasticity on source process signatures, off-fault damage patterns and ground shaking. Independent of rupture style, asymmetric damage patterns across the fault are produced that contribute to the total seismic moment, and even dominantly at high angles between the fault and the maximum principal background stress. The off-fault plastic strain fields induced by transitions between rupture styles reveal characteristic signatures of the mechanical source processes during the transition. Comparing different rupture styles in elastic and elasto-visco-plastic media to identify signatures of off-fault plasticity, we find varying degrees of alteration of near-field radiation due to plastic energy dissipation. Subshear pulses suffer more peak particle velocity reduction due to plasticity than cracks. Supershear ruptures are affected even more. The occurrence of multiple rupture fronts affect seismic potency release rate, amplitude spectra, peak particle velocity distributions and near-field seismograms. Our simulations enable us to trace features of source processes in synthetic seismograms, for example exhibiting a re-activation of slip. Such physical models may provide starting points for future investigations of field properties of earthquake source mechanisms and natural fault conditions. In the long-term, our findings may be helpful for seismic hazard analysis and the improvement of seismic source models.

Ruptured hemidiaphragm after bilateral lung transplantation.

PubMed

Gómez-Arnau, J; Novoa, N; Isidro, M G; Plaza, A; Galindo, F; Ezquerro, C

1999-04-01

A case of right hemidiaphragm rupture and abdominal herniation into the thorax occurring during the immediate post-operative course of double-lung transplantation is reported. This complication has not been reported previously. We examine the possible aetiology and suggest that the direct cause could be an increase in intra-abdominal pressure during chest physiotherapy.

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.

Achilles tendon rupture: physiotherapy and endoscopy-assisted surgical treatment of a common sports injury

PubMed Central

Doral, Mahmut Nedim; Bozkurt, Murat; Turhan, Egemen; Dönmez, Gürhan; Demirel, Murat; Kaya, Defne; Ateşok, Kıvanç; Atay, Özgür Ahmet; Maffulli, Nicola

2010-01-01

Although the Achilles tendon (AT) is the strongest tendon in the human body, rupture of this tendon is one of the most common sports injuries in the athletic population. Despite numerous nonoperative and operative methods that have been described, there is no universal agreement about the optimal management strategy of acute total AT ruptures. The management of AT ruptures should aim to minimize the morbidity of the injury, optimize rapid return to full function, and prevent complications. Since endoscopy-assisted percutaneous AT repair allows direct visualization of the synovia and protects the paratenon that is important in biological healing of the AT, this technique becomes a reasonable treatment option in AT ruptures. Furthermore, Achilles tendoscopy technique may decrease the complications about the sural nerve. Also, early functional postoperative physiotherapy following surgery may improve the surgical outcomes. PMID:24198562

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.

A global search inversion for earthquake kinematic rupture history: Application to the 2000 western Tottori, Japan earthquake

USGS Publications Warehouse

Piatanesi, A.; Cirella, A.; Spudich, P.; Cocco, M.

2007-01-01

We present a two-stage nonlinear technique to invert strong motions records and geodetic data to retrieve the rupture history of an earthquake on a finite fault. To account for the actual rupture complexity, the fault parameters are spatially variable peak slip velocity, slip direction, rupture time and risetime. The unknown parameters are given at the nodes of the subfaults, whereas the parameters within a subfault are allowed to vary through a bilinear interpolation of the nodal values. The forward modeling is performed with a discrete wave number technique, whose Green's functions include the complete response of the vertically varying Earth structure. During the first stage, an algorithm based on the heat-bath simulated annealing generates an ensemble of models that efficiently sample the good data-fitting regions of parameter space. In the second stage (appraisal), the algorithm performs a statistical analysis of the model ensemble and computes a weighted mean model and its standard deviation. This technique, rather than simply looking at the best model, extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter. We present some synthetic tests to show the effectiveness of the method and its robustness to uncertainty of the adopted crustal model. Finally, we apply this inverse technique to the well recorded 2000 western Tottori, Japan, earthquake (Mw 6.6); we confirm that the rupture process is characterized by large slip (3-4 m) at very shallow depths but, differently from previous studies, we imaged a new slip patch (2-2.5 m) located deeper, between 14 and 18 km depth. Copyright 2007 by the American Geophysical Union.

Metrics for comparing dynamic earthquake rupture simulations

USGS Publications Warehouse

Barall, Michael; Harris, Ruth A.

2014-01-01

Earthquakes are complex events that involve a myriad of interactions among multiple geologic features and processes. One of the tools that is available to assist with their study is computer simulation, particularly dynamic rupture simulation. A dynamic rupture simulation is a numerical model of the physical processes that occur during an earthquake. Starting with the fault geometry, friction constitutive law, initial stress conditions, and assumptions about the condition and response of the near‐fault rocks, a dynamic earthquake rupture simulation calculates the evolution of fault slip and stress over time as part of the elastodynamic numerical solution (Ⓔ see the simulation description in the electronic supplement to this article). The complexity of the computations in a dynamic rupture simulation make it challenging to verify that the computer code is operating as intended, because there are no exact analytic solutions against which these codes’ results can be directly compared. One approach for checking if dynamic rupture computer codes are working satisfactorily is to compare each code’s results with the results of other dynamic rupture codes running the same earthquake simulation benchmark. To perform such a comparison consistently, it is necessary to have quantitative metrics. In this paper, we present a new method for quantitatively comparing the results of dynamic earthquake rupture computer simulation codes.

Surface Rupture Characteristics and Rupture Mechanics of the Yushu Earthquake (Ms7.1), 14/04/2010

NASA Astrophysics Data System (ADS)

Pan, J.; Li, H.; Xu, Z.; Li, N.; Wu, F.; Guo, R.; Zhang, W.

2010-12-01

On April 14th 2010, a disastrous earthquake (Ms 7.1) struck Yushu County, Qinghai Province, China, killing thousands of people. This earthquake occurred as a result of sinistral strike-slip faulting on the western segment of the Xianshuihe Fault zone in eastern Tibetan Plateau. Our group conducted scientific investigation in the field on co-seismic surface rupture and active tectonics in the epicenter area immediately after the earthquake. Here, we introduce our preliminary results on the surface ruptures and rupture mechanics of the Yushu Earthquake. The surface rupture zone of Yushu earthquake, which is about 49 km-long, consists of 3 discontinuous left stepping rupture segments, which are 19 km, 22 km, and about 8 km, respectively, from west to east. Each segment consists of a series of right stepping en-echelon branch ruptures. The branch ruptures consist of interphase push-up and tension fissures or simply en-echelon tension fissures. The co-seismic displacements had been surveyed with a total station in detail on landmarks such as rivers, gullies, roads, farmlands, wire poles, and fences. The maximum offset measured is 2.3m, located near the Guoyangyansongduo Village. There are 3 offset peaks along the rupture zone corresponding to the 3 segments of the surface rupture zone. The maximum offsets in the west, central, and east segment rupture zones are 1.4m, 2.3m, and 1.6m respectively. The surface rupture zone of Yushu earthquake strikes in a 310°NW direction. The fault plane dips to the northeast and the dip angle is about 81°. The rupture zone is developed in transtension setting. Tension normal fault developed during the sinistral strike-slip process of the fault. The valley west of Yushu City and the Longbao Lake are both pull-apart basins formed during the transtension activity of the fault.

Instability, rupture and fluctuations in thin liquid films: Theory and computations

NASA Astrophysics Data System (ADS)

Gvalani, Rishabh; Duran-Olivencia, Miguel; Kalliadasis, Serafim; Pavliotis, Grigorios

2017-11-01

Thin liquid films are ubiquitous in natural phenomena and technological applications. They are commonly studied via deterministic hydrodynamic equations, but thermal fluctuations often play a crucial role that still needs to be understood. An example of this is dewetting, which involves the rupture of a thin liquid film and the formation of droplets. Such a process is thermally activated and requires fluctuations to be taken into account self-consistently. Here we present an analytical and numerical study of a stochastic thin-film equation derived from first principles. We scrutinise the behaviour of the stochastic thin film equation in the limit of perfectly correlated noise along the wall-normal direction. We also perform Monte Carlo simulations of the stochastic equation by adopting a numerical scheme based on a spectral collocation method. The numerical scheme allows us to explore the fluctuating dynamics of the thin film and the behaviour of the system's free energy close to rupture. Finally, we also study the effect of the noise intensity on the rupture time, which is in good agreement with previous works. Imperial College London (ICL) President's PhD Scholarship; European Research Council Advanced Grant No. 247031; EPSRC Grants EP/L025159, EP/L020564, EP/P031587, EP/L024926, and EP/L016230/1.

Rupture Propagation for Stochastic Fault Models

NASA Astrophysics Data System (ADS)

Favreau, P.; Lavallee, D.; Archuleta, R.

2003-12-01

The inversion of strong motion data of large earhquakes give the spatial distribution of pre-stress on the ruptured faults and it can be partially reproduced by stochastic models, but a fundamental question remains: how rupture propagates, constrained by the presence of spatial heterogeneity? For this purpose we investigate how the underlying random variables, that control the pre-stress spatial variability, condition the propagation of the rupture. Two stochastic models of prestress distributions are considered, respectively based on Cauchy and Gaussian random variables. The parameters of the two stochastic models have values corresponding to the slip distribution of the 1979 Imperial Valley earthquake. We use a finite difference code to simulate the spontaneous propagation of shear rupture on a flat fault in a 3D continuum elastic body. The friction law is the slip dependent friction law. The simulations show that the propagation of the rupture front is more complex, incoherent or snake-like for a prestress distribution based on Cauchy random variables. This may be related to the presence of a higher number of asperities in this case. These simulations suggest that directivity is stronger in the Cauchy scenario, compared to the smoother rupture of the Gauss scenario.

Possible Interactions between the 2012 Mw 7.8 Haida Gwaii Subduction Earthquake and the Transform Queen Charlotte Fault

NASA Astrophysics Data System (ADS)

Hobbs, T. E.; Cassidy, J. F.; Dosso, S. E.

2014-12-01

This paper examines the effect of the October 2012 Mw 7.8 Haida Gwaii earthquake on aftershock nodal planes and the neighboring Queen Charlotte Fault (QCF) through Coulomb modeling and directivity analysis. The Haida Gwaii earthquake was the largest thrust event recorded in this region and ruptured an area of ~150 by 40 km on a gently NE-dipping fault off the west coast of Moresby Island, British Columbia. It is particularly interesting as it is located just to the west of the QCF, the predominantly right-lateral strike-slip fault separating the Pacific and North American plates. The QCF was the site of the largest recorded earthquake in Canada: the 1949 Ms 8.1 strike-slip earthquake whose rupture extended as far south as this 2012 event and roughly as far north as an Mw7.5 strike slip event at Craig, Alaska, which occurred just two months later in January 2013. The 75 km long portion of the QCF south of the 1949 rupture has not had a large (M ≥ 7) earthquake in over 116 years, representing a significant seismic gap. Coulomb stress transfer analysis is performed using finite fault models which incorporate seismic and geodetic data. Static stress changes are projected onto aftershock nodal planes and the QCF, including an inferred southern seismic gap. We find up to 86% of aftershocks are consistent with triggering, and as high as 96% for normal faulting events. The QCF experiences static stress changes greater than the empirically-determined threshold for triggering, with positive stress changes predicted for roughly half of the seismic gap region. Added stress from the mainshock and a lack of post-mainshock events make this seismic gap a likely location for future earthquakes. Empirical Green's function and directivity analyses are also performed to constrain rupture kinematics of the mainshock using systematic azimuthal variations in relative source time functions. Results indicate rupture progressed mainly to the northwest within 15o of the direction of the 2013 Craig epicenter, with at least two sources of significant moment release. These results explain observed surface wave amplification at Alaskan seismic stations and support the idea that strong surface wave shaking may be linked to the possible delayed triggering of the Mw 7.5 Craig event, through an unknown intermediate mechanism that accounts for the two-month hiatus.

The Extrapolation of Families of Curves by Recurrence Relations, with Application to Creep-Rupture Data

NASA Technical Reports Server (NTRS)

Mendelson, A.; Manson, S. S.

1960-01-01

A method using finite-difference recurrence relations is presented for direct extrapolation of families of curves. The method is illustrated by applications to creep-rupture data for several materials and it is shown that good results can be obtained without the necessity for any of the usual parameter concepts.

[Effects of posterior tibial slope on non-contact anterior cruciate ligament rupture and stability of anterior cruciate ligament rupture knee].

PubMed

Yue, De-bo; E, Sen; Wang, Bai-liang; Wang, Wei-guo; Guo, Wan-shou; Zhang, Qi-dong

2013-05-07

To retrospectively explore the correlation between anterior cruciate ligament (ACL)-ruptured knees, stability of ACL-rupture knee and posterior tibial slope (PTS). From January 2008 to October 2012, 150 knees with ACL rupture underwent arthroscopic surgery for ACL reconstruction. A control group was established for subjects undergoing arthroscopic surgery without ACL rupture during the same period. PTS was measured on a digitalized lateral radiograph. Lachman and mechanized pivot shift tests were performed for assessing the stability of knee. There was significant difference (P = 0.007) in PTS angle between the patients with ACL rupture (9.5 ± 2.2 degrees) and the control group (6.6 ± 1.8 degrees). Only among females, increased slope of tibial plateau had effect on the Lachman test. There was a higher positive rate of pivot shift test in patients of increased posterior slope in the ACL rupture group. Increased posterior tibial slope (>6.6) appears to contribute to non-contact ACL injuries in females. And the changes of tibial slope have no effect upon the Lachman test. However, large changes in tibial slope affect pivot shift.

Tsunami Early Warning Within Five Minutes

NASA Astrophysics Data System (ADS)

Lomax, Anthony; Michelini, Alberto

2013-09-01

Tsunamis are most destructive at near to regional distances, arriving within 20-30 min after a causative earthquake; effective early warning at these distances requires notification within 15 min or less. The size and impact of a tsunami also depend on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of the earthquake rupture. Currently, the primary seismic discriminant for tsunami potential is the centroid-moment tensor magnitude, M {w/CMT}, representing the product LWD and estimated via an indirect inversion procedure. However, the obtained M {w/CMT} and the implied LWD value vary with rupture depth, earth model, and other factors, and are only available 20-30 min or more after an earthquake. The use of more direct discriminants for tsunami potential could avoid these problems and aid in effective early warning, especially for near to regional distances. Previously, we presented a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measurements on P-wave seismograms—the predominant period on velocity records, T d , and the likelihood, T {50/Ex}, that the high-frequency, apparent rupture-duration, T 0, exceeds 50-55 s. We have shown that T d and T 0 are related to the critical rupture parameters L, W, D, and z, and that either of the period-duration products T d T 0 or T d T {50/Ex} gives more information on tsunami impact and size than M {w/CMT}, M wp, and other currently used discriminants. These results imply that tsunami potential is not directly related to the product LWD from the "seismic" faulting model, as is assumed with the use of the M {w/CMT} discriminant. Instead, information on rupture length, L, and depth, z, as provided by T d T 0 or T d T {50/Ex}, can constrain well the tsunami potential of an earthquake. We introduce here special treatment of the signal around the S arrival at close stations, a modified, real-time, M wpd(RT) magnitude, and other procedures to enable early estimation of event parameters and tsunami discriminants. We show that with real-time data currently available in most regions of tsunami hazard, event locations, m b and M wp magnitudes, and the direct, period-duration discriminant, T d T {50/Ex} can be determined within 5 min after an earthquake occurs, and T 0, T d T 0, and M wpd(RT) within approximately 10 min. This processing is implemented and running continuously in real-time within the Early-est earthquake monitor at INGV-Rome (http://early-est.rm.ingv.it). We also show that the difference m b - log10( T d T 0) forms a rapid discriminant for slow, tsunami earthquakes. The rapid availability of these measurements can aid in faster and more reliable tsunami early warning for near to regional distances.

Regularization of rupture dynamics along bi-material interfaces: a parametric study and simulations of the Tohoku earthquake

NASA Astrophysics Data System (ADS)

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

2015-04-01

Faults are often interfaces between materials with different elastic properties. This is generally the case of plate boundaries in subduction zones, where the ruptures extend for many kilometers crossing materials with strong impedance contrasts (oceanic crust, continental crust, mantle wedge, accretionary prism). From a physical point of view, several peculiar features emerged both from analogic experiments and numerical simulations for a rupture propagating along a bimaterial interface. The elastodynamic flux at the rupture tip breaks its symmetry, inducing normal stress changes and an asymmetric propagation. This latter was widely shown for rupture velocity and slip rate (e.g. Xia et al, 2005) and was supposed to generate an asymmetric distribution of the aftershocks (Rubin and Ampuero, 2007). The bimaterial problem coupled with a Coulomb friction law is ill-posed for a wide range of impedance contrasts, due to a missing length scale in the instantaneous response to the normal traction changes. The ill-posedness also results into simulations no longer independent of the grid size. A regularization can be introduced by delaying the tangential traction from the normal traction as suggested by Cochard and Rice (2000) and Ranjith and Rice (2000) δσeff α|v|+-v* δt = δσ (σn - σeff) where σeff represents the effective normal stress to be used in the Coulomb friction. This regularization introduces two delays depending on the slip rate and on a fixed time scale. In this study we performed a large number of 2D numerical simulations of in plane rupture with the spectral element method dynamic and we systematically investigated the effect of parameter selection on the rupture propagation, dissipation and radiation, by also performing a direct comparison with solutions provided by numerical and experimental results. We found that a purely time-dependent regularization requires a fine tuning rapidly jumping from a too fast, ineffective delay to a slow, invasive, regularization as a function of the actual slip rate. Conversely, the choice of a fixed relaxation length, smaller than the critical slip weakening distance, provides a reliable class of solutions for a wide range of elastic and frictional parameters. Nevertheless critical rupture stages, such as the nucleation or the very fast steady-state propagation may show resolution problems and may take advantage of adaptive schemes, with a space/time variation of the parameters. We used recipes for bimaterial regularization to perform along-dip dynamic simulations of the Tohoku earthquake in the framework of a slip weakening model, with a realistic description of the geometry of the interface and the geological structure. We finely investigated the role of the impedance contrasts on the evolution of the rupture and short wavelength radiation. We also show that pathological effects may arise from a bad selection of regularization parameters.

Outcomes for Symptomatic Abdominal Aortic Aneurysms in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP)

PubMed Central

Soden, Peter A.; Zettervall, Sara L.; Ultee, Klaas H.J.; Darling, Jeremy D.; Buck, Dominique B.; Hile, Chantel N.; Hamdan, Allen D.; Schermerhorn, Marc L.

2016-01-01

Introduction Historically symptomatic AAAs were found to have intermediate mortality compared to asymptomatic and ruptured AAAs but, with wider EVAR use, a more recent study suggested mortality of symptomatic aneurysms were similar to asymptomatic AAAs. These prior studies were limited by small numbers. The purpose of this study is to evaluate the mortality and morbidity associated with symptomatic AAA repair in a large contemporary population. Methods All patients undergoing infrarenal AAA repair were identified in the 2011–2013 ACS-NSQIP, Vascular Surgery targeted module. We excluded acute conversions to open repair and those for whom the surgical indication was embolization, dissection, thrombosis, or not documented. We compared 30-day mortality and major adverse events (MAE) for asymptomatic, symptomatic, and ruptured AAA repair, stratified by EVAR and open repair, with univariate analysis and multivariable logistic regression. Results 5502 infrarenal AAAs were identified, 4495 asymptomatic (830 open repair, 3665 [82%] EVAR), 455 symptomatic (143 open, 312 [69%] EVAR), and 552 ruptured aneurysms (263 open, 289 [52%] EVAR). Aneurysm diameter was similar between asymptomatic and symptomatic AAAs, when stratified by procedure type, but larger for ruptured aneurysms (EVAR symptomatic 5.8cm ±1.6 vs. ruptured 7.5cm ±2.0, P<.001; open repair symptomatic 6.4cm ±1.9 vs. ruptured 8.0cm ±1.9, P<.001). The proportion of females was similar in symptomatic and ruptured AAA (27% vs. 23%, P=.14, respectively), but lower in asymptomatic AAA (20%, P<.001). Symptomatic AAAs had intermediate 30-day mortality compared to asymptomatic and ruptured aneurysms after both EVAR (asymptomatic 1.4% vs. symptomatic 3.8%, P=.001; symptomatic vs. 22% ruptured, P<.001) and open repair (asymptomatic 4.3% vs. symptomatic 7.7% , P=.08; symptomatic vs. 57% ruptured, P<.001). After adjustment for age, gender, repair type, dialysis dependence, and history of severe COPD, patients undergoing repair of symptomatic AAAs were twice as likely to die within 30-days compared to those with asymptomatic aneurysms (OR 2.1, 95%CI 1.3–3.5). When stratified by repair type the effect size and direction of the odds ratios were similar (EVAR OR 2.4, CI 1.2–4.7; open repair OR 1.8, CI 0.86–3.9), although not significant for open repair. Patients with ruptured aneurysms had a sevenfold increased risk of 30-day mortality compared to symptomatic patients (OR 6.5, CI 4.1–10.6). Conclusion Patients with symptomatic AAAs had a two-fold increased risk of perioperative mortality, compared to asymptomatic aneurysms undergoing repair. Furthermore, patients with ruptured aneurysms have a seven-fold increased risk of mortality compared to symptomatic aneurysms. PMID:27146791

Heterogeneous rupture on homogenous faults: Three-dimensional spontaneous rupture simulations with thermal pressurization

NASA Astrophysics Data System (ADS)

Urata, Yumi; Kuge, Keiko; Kase, Yuko

2008-11-01

To understand role of fluid on earthquake rupture processes, we investigated effects of thermal pressurization on spatial variation of dynamic rupture by computing spontaneous rupture propagation on a rectangular fault. We found thermal pressurization can cause heterogeneity of rupture even on a fault of uniform properties. On drained faults, tractions drop linearly with increasing slip in the same way everywhere. However, by changing the drained condition to an undrained one, the slip-weakening curves become non-linear and depend on locations on faults with small shear zone thickness w, and the dynamic frictional stresses vary spatially and temporally. Consequently, the super-shear transition fault length decreases for small w, and the final slip distribution can have some peaks regardless of w, especially on undrained faults. These effects should be taken into account of determining dynamic rupture parameters and modeling earthquake cycles when the presence of fluid is suggested in the source regions.

Factors that influence the outcome of open urethroplasty for pelvis fracture urethral defect (PFUD): an observational study from a single high-volume tertiary care center.

PubMed

Fu, Qiang; Zhang, Yu-meng; Barbagli, Guido; Zhang, Jiong; Xie, Hong; Sa, Ying-long; Jin, San-bao; Xu, Yue-min

2015-12-01

To report the clinical features of pelvic fracture urethral injury (PFUI) and assess the real effect of factors that are believed to have adverse effects on delayed urethroplasty. An observational descriptive study in a single urological center examined 376 male patients diagnosed with PFUI who underwent open urethroplasty from 2009 to 2013. Analyzed factors included patient age at the time of injury, etiology of PFUI, type of emergency treatment, concomitant injuries, length and position of stricture, type of urethroplasty and the outcome of surgery. Univariate and multivariate logistic regression analyses were applied, together with analytical statistic methods such as t test and Chi-square test. The overall success rate of delayed urethroplasty was 80.6 %. Early realignment was associated with reduced stricture length and had beneficial effect on delayed surgery. Concomitant rectum rupture, strictures longer than 1.6 cm and strictures closer than 3 cm to the bladder neck were indicators of poor outcome. Age, type of injury, urethral fistula and bladder rupture were not significant predicators of surgery outcome. Failed direct vision internal urethrotomy and urethroplasty had no significant influence on salvage operation. The outcome of posterior urethroplasty is affected by multiple factors. Early realignment has beneficial effect; while the length and position of stricture and its distance to bladder neck plays the key role, rectum rupture at the time of injury is also an indicator of poor outcome. The effect of other factors seems insignificant.

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.

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.

75 FR 26681 - Airworthiness Directives; Turbomeca S.A. Arriel 2B and 2B1 Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... displacement of the HP blade relative to the disk in case of blade lock rupture or opening, therefore... repetitive borescope inspection of the engine for rearward displacement of the high-pressure turbine (HP... axial displacement of the HP blade relative to the disk in case of blade lock rupture or opening...

75 FR 59065 - Airworthiness Directives; Turboméca S.A. Arriel 2B and 2B1 Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-27

... displacement of the HP blade relative to the disk in case of blade lock rupture or opening, therefore... limit axial displacement of the HP blade relative to the disk in case of blade lock rupture or opening... and the HP blade platform. Introduction of these dampers has demonstrated to limit axial displacement...

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.

Towards a robust framework for Probabilistic Tsunami Hazard Assessment (PTHA) for local and regional tsunami in New Zealand

NASA Astrophysics Data System (ADS)

Mueller, Christof; Power, William; Fraser, Stuart; Wang, Xiaoming

2013-04-01

Probabilistic Tsunami Hazard Assessment (PTHA) is conceptually closely related to Probabilistic Seismic Hazard Assessment (PSHA). The main difference is that PTHA needs to simulate propagation of tsunami waves through the ocean and cannot rely on attenuation relationships, which makes PTHA computationally more expensive. The wave propagation process can be assumed to be linear as long as water depth is much larger than the wave amplitude of the tsunami. Beyond this limit a non-linear scheme has to be employed with significantly higher algorithmic run times. PTHA considering far-field tsunami sources typically uses unit source simulations, and relies on the linearity of the process by later scaling and combining the wave fields of individual simulations to represent the intended earthquake magnitude and rupture area. Probabilistic assessments are typically made for locations offshore but close to the coast. Inundation is calculated only for significantly contributing events (de-aggregation). For local and regional tsunami it has been demonstrated that earthquake rupture complexity has a significant effect on the tsunami amplitude distribution offshore and also on inundation. In this case PTHA has to take variable slip distributions and non-linearity into account. A unit source approach cannot easily be applied. Rupture complexity is seen as an aleatory uncertainty and can be incorporated directly into the rate calculation. We have developed a framework that manages the large number of simulations required for local PTHA. As an initial case study the effect of rupture complexity on tsunami inundation and the statistics of the distribution of wave heights have been investigated for plate-interface earthquakes in the Hawke's Bay region in New Zealand. Assessing the probability that water levels will be in excess of a certain threshold requires the calculation of empirical cumulative distribution functions (ECDF). We compare our results with traditional estimates for tsunami inundation simulations that do not consider rupture complexity. De-aggregation based on moment magnitude alone might not be appropriate, because the hazard posed by any individual event can be underestimated locally if rupture complexity is ignored.

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.

The 1994 Northridge, California, earthquake: Investigation of rupture velocity, risetime, and high-frequency radiation

USGS Publications Warehouse

Hartzell, S.; Liu, P.; Mendoza, C.

1996-01-01

A hybrid global search algorithm is used to solve the nonlinear problem of calculating slip amplitude, rake, risetime, and rupture time on a finite fault. Thirty-five strong motion velocity records are inverted by this method over the frequency band from 0.1 to 1.0 Hz for the Northridge earthquake. Four regions of larger-amplitude slip are identified: one near the hypocenter at a depth of 17 km, a second west of the hypocenter at about the same depth, a third updip from the hypocenter at a depth of 10 km, and a fourth updip from the hypocenter and to the northwest. The results further show an initial fast rupture with a velocity of 2.8 to 3.0 km/s followed by a slow termination of the rupture with velocities of 2.0 to 2.5 km/s. The initial energetic rupture phase lasts for 3 s, extending out 10 km from the hypocenter. Slip near the hypocenter has a short risetime of 0.5 s, which increases to 1.5 s for the major slip areas removed from the hypocentral region. The energetic rupture phase is also shown to be the primary source of high-frequency radiation (1-15 Hz) by an inversion of acceleration envelopes. The same global search algorithm is used in the envelope inversion to calculate high-frequency radiation intensity on the fault and rupture time. The rupture timing from the low- and high-frequency inversions is similar, indicating that the high frequencies are produced primarily at the mainshock rupture front. Two major sources of high-frequency radiation are identified within the energetic rupture phase, one at the hypocenter and another deep source to the west of the hypocenter. The source at the hypocenter is associated with the initiation of rupture and the breaking of a high-stress-drop asperity and the second is associated with stopping of the rupture in a westerly direction.

Comparing slow and fast rupture in laboratory experiments

NASA Astrophysics Data System (ADS)

Aben, F. M.; Brantut, N.; David, E.; Mitchell, T. M.

2017-12-01

During the brittle failure of rock, elastically stored energy is converted into a localized fracture plane and surrounding fracture damage, seismic radiation, and thermal energy. However, the partitioning of energy might vary with the rate of elastic energy release during failure. Here, we present the results of controlled (slow) and dynamic (fast) rupture experiments on dry Lanhélin granite and Westerly granite samples, performed under triaxial stress conditions at confining pressures of 50 and 100 MPa. During the tests, we measured sample shortening, axial load and local strains (with 2 pairs of strain gauges glued directly onto the sample). In addition, acoustic emissions (AEs) and changes in seismic velocities were monitored. The AE rate was used as an indicator to manually control the axial load on the sample to stabilize rupture in the quasi-static failure experiments. For the dynamic rupture experiments a constant strain rate of 10-5 s-1 was applied until sample failure. A third experiment, labeled semi-controlled rupture, involved controlled rupture up to a point where the rupture became unstable and the remaining elastic energy was released dynamically. All experiments were concluded after a macroscopic fracture had developed across the whole sample and frictional sliding commenced. Post-mortem samples were epoxied, cut and polished to reveal the macroscopic fracture and the surrounding damage zone. The samples failed with average rupture velocities varying from 5x10-6 m/s up to >> 0.1 m/s. The analyses of AE locations on the slow ruptures reveal that within Westerly granite samples - with a smaller grain size - fracture planes are disbanded in favor of other planes when a geometrical irregularity is encountered. For the coarser grained Lanhélin granite a single fracture plane is always formed, although irregularities are recognized as well. The semi-controlled experiments show that for both rock types the rupture can become unstable in response to these irregularities. In Westerly granite, slow rupture experiments tend to produce complex fracture patterns while during the dynamic rupture experiments secondary rupture planes are not formed. These findings show that grain or flaw size, flaw distribution, and rupture speed strongly influence fracture localization and propagation.

Comparison of ground motions from hybrid simulations to nga prediction equations

USGS Publications Warehouse

Star, L.M.; Stewart, J.P.; Graves, R.W.

2011-01-01

We compare simulated motions for a Mw 7.8 rupture scenario on the San Andreas Fault known as the ShakeOut event, two permutations with different hypocenter locations, and a Mw 7.15 Puente Hills blind thrust scenario, to median and dispersion predictions from empirical NGA ground motion prediction equations. We find the simulated motions attenuate faster with distance than is predicted by the NGA models for periods less than about 5.0 s After removing this distance attenuation bias, the average residuals of the simulated events (i.e., event terms) are generally within the scatter of empirical event terms, although the ShakeOut simulation appears to be a high static stress drop event. The intraevent dispersion in the simulations is lower than NGA values at short periods and abruptly increases at 1.0 s due to different simulation procedures at short and long periods. The simulated motions have a depth-dependent basin response similar to the NGA models, and also show complex effects in which stronger basin response occurs when the fault rupture transmits energy into a basin at low angle, which is not predicted by the NGA models. Rupture directivity effects are found to scale with the isochrone parameter ?? 2011, Earthquake Engineering Research Institute.

Source Parameters and Rupture Directivities of Earthquakes Within the Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Allen, A. A.; Chen, X.

2017-12-01

The Mendocino Triple Junction (MTJ), a region in the Cascadia subduction zone, produces a sizable amount of earthquakes each year. Direct observations of the rupture properties are difficult to achieve due to the small magnitudes of most of these earthquakes and lack of offshore observations. The Cascadia Initiative (CI) project provides opportunities to look at the earthquakes in detail. Here we look at the transform plate boundary fault located in the MTJ, and measure source parameters of Mw≥4 earthquakes from both time-domain deconvolution and spectral analysis using empirical Green's function (EGF) method. The second-moment method is used to infer rupture length, width, and rupture velocity from apparent source duration measured at different stations. Brune's source model is used to infer corner frequency and spectral complexity for stacked spectral ratio. EGFs are selected based on their location relative to the mainshock, as well as the magnitude difference compared to the mainshock. For the transform fault, we first look at the largest earthquake recorded during the Year 4 CI array, a Mw5.72 event that occurred in January of 2015, and select two EGFs, a Mw1.75 and a Mw1.73 located within 5 km of the mainshock. This earthquake is characterized with at least two sub-events, with total duration of about 0.3 second and rupture length of about 2.78 km. The earthquake is rupturing towards west along the transform fault, and both source durations and corner frequencies show strong azimuthal variations, with anti-correlation between duration and corner frequency. The stacked spectral ratio from multiple stations with the Mw1.73 EGF event shows deviation from pure Brune's source model following the definition from Uchide and Imanishi [2016], likely due to near-field recordings with rupture complexity. We will further analyze this earthquake using more EGF events to test the reliability and stability of the results, and further analyze three other Mw≥4 earthquakes within the array.

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.

Rupture, waves and earthquakes.

PubMed

Uenishi, Koji

2017-01-01

Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but "extraordinary" phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable.

Rupture, waves and earthquakes

PubMed Central

UENISHI, Koji

2017-01-01

Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but “extraordinary” phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable. PMID:28077808

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.

Dynamic rupture simulations on a fault network in the Corinth Rift

NASA Astrophysics Data System (ADS)

Durand, V.; Hok, S.; Boiselet, A.; Bernard, P.; Scotti, O.

2017-03-01

The Corinth rift (Greece) is made of a complex network of fault segments, typically 10-20 km long separated by stepovers. Assessing the maximum magnitude possible in this region requires accounting for multisegment rupture. Here we apply numerical models of dynamic rupture to quantify the probability of a multisegment rupture in the rift, based on the knowledge of the fault geometry and on the magnitude of the historical and palaeoearthquakes. We restrict our application to dynamic rupture on the most recent and active fault network of the western rift, located on the southern coast. We first define several models, varying the main physical parameters that control the rupture propagation. We keep the regional stress field and stress drop constant, and we test several fault geometries, several positions of the faults in their seismic cycle, several values of the critical distance (and so several fracture energies) and two different hypocentres (thus testing two directivity hypothesis). We obtain different scenarios in terms of the number of ruptured segments and the final magnitude (between M = 5.8 for a single segment rupture to M = 6.4 for a whole network rupture), and find that the main parameter controlling the variability of the scenarios is the fracture energy. We then use a probabilistic approach to quantify the probability of each generated scenario. To do that, we implement a logical tree associating a weight to each model input hypothesis. Combining these weights, we compute the probability of occurrence of each scenario, and show that the multisegment scenarios are very likely (52 per cent), but that the whole network rupture scenario is unlikely (14 per cent).

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.

Near-field observations of microearthquake source physics using dense array

NASA Astrophysics Data System (ADS)

Chen, X.; Nakata, N.; Abercrombie, R. E.

2017-12-01

The recorded waveform includes contributions from earthquake source properties and propagation effects, leading to long-standing trade-off problems between site/path effects and source effects. This problem is especially significant for small earthquakes where the corner frequencies are within similar ranges of near-site attenuation effects. Fortunately, this problem can be remedied by dense near-field recordings at high frequency, and large databases with wide magnitude range. The 2016 IRIS wavefield experiment provides high-quality recordings of earthquake sequences in north-central Oklahoma with about 400 sensors in 15 km area. Preliminary processing of the IRIS wavefield array resulted with about 20,000 microearthquakes ranging from M-1 to M2, while only 2 earthquakes are listed in the catalog during the same time period. A preliminary examination of the catalog reveals three similar magnitude earthquakes (M 2) occurred at similar locations within 9 seconds of each other. Utilizing this catalog, we will combine individual empirical Green's function (EGF) analysis and stacking over multiple EGFs to examine if there are any systematic variations of source time functions and spectral ratios across the array, which will provide constrains of rupture complexity, directivity and earthquake interactions. For example, this would help us to understand if these three earthquakes rupture overlapping fault patches from cascading failure, or from repeated rupture at the same slip patch due to external stress loading. Deciphering the interaction at smaller scales with near-field observations is important for a controlled earthquake experiment.

Depth varying rupture properties during the 2015 Mw 7.8 Gorkha (Nepal) earthquake

NASA Astrophysics Data System (ADS)

Yue, Han; Simons, Mark; Duputel, Zacharie; Jiang, Junle; Fielding, Eric; Liang, Cunren; Owen, Susan; Moore, Angelyn; Riel, Bryan; Ampuero, Jean Paul; Samsonov, Sergey V.

2017-09-01

On April 25th 2015, the Mw 7.8 Gorkha (Nepal) earthquake ruptured a portion of the Main Himalayan Thrust underlying Kathmandu and surrounding regions. We develop kinematic slip models of the Gorkha earthquake using both a regularized multi-time-window (MTW) approach and an unsmoothed Bayesian formulation, constrained by static and high rate GPS observations, synthetic aperture radar (SAR) offset images, interferometric SAR (InSAR), and teleseismic body wave records. These models indicate that Kathmandu is located near the updip limit of fault slip and approximately 20 km south of the centroid of fault slip. Fault slip propagated unilaterally along-strike in an ESE direction for approximately 140 km with a 60 km cross-strike extent. The deeper portions of the fault are characterized by a larger ratio of high frequency (0.03-0.2 Hz) to low frequency slip than the shallower portions. From both the MTW and Bayesian results, we can resolve depth variations in slip characteristics, with higher slip roughness, higher rupture velocity, longer rise time and higher complexity of subfault source time functions in the deeper extents of the rupture. The depth varying nature of rupture characteristics suggests that the up-dip portions are characterized by relatively continuous rupture, while the down-dip portions may be better characterized by a cascaded rupture. The rupture behavior and the tectonic setting indicate that the earthquake may have ruptured both fully seismically locked and a deeper transitional portions of the collision interface, analogous to what has been seen in major subduction zone earthquakes.

Why the 2002 Denali fault rupture propagated onto the Totschunda fault: implications for fault branching and seismic hazards

USGS Publications Warehouse

Schwartz, David P.; Haeussler, Peter J.; Seitz, Gordon G.; Dawson, Timothy E.

2012-01-01

The propagation of the rupture of the Mw7.9 Denali fault earthquake from the central Denali fault onto the Totschunda fault has provided a basis for dynamic models of fault branching in which the angle of the regional or local prestress relative to the orientation of the main fault and branch plays a principal role in determining which fault branch is taken. GeoEarthScope LiDAR and paleoseismic data allow us to map the structure of the Denali-Totschunda fault intersection and evaluate controls of fault branching from a geological perspective. LiDAR data reveal the Denali-Totschunda fault intersection is structurally simple with the two faults directly connected. At the branch point, 227.2 km east of the 2002 epicenter, the 2002 rupture diverges southeast to become the Totschunda fault. We use paleoseismic data to propose that differences in the accumulated strain on each fault segment, which express differences in the elapsed time since the most recent event, was one important control of the branching direction. We suggest that data on event history, slip rate, paleo offsets, fault geometry and structure, and connectivity, especially on high slip rate-short recurrence interval faults, can be used to assess the likelihood of branching and its direction. Analysis of the Denali-Totschunda fault intersection has implications for evaluating the potential for a rupture to propagate across other types of fault intersections and for characterizing sources of future large earthquakes.

The distribution of modified mercalli intensity in the 18 April 1906 San Francisco earthquake

USGS Publications Warehouse

Boatwright, J.; Bundock, H.

2008-01-01

We analyze Boatwright and Bundock's (2005) modified Mercalli intensity (MMI) map for the 18 April 1906 San Francisco earthquake, reviewing their interpretation of the MMI scale and testing their correlation of 1906 cemetery damage with MMI intensity. We consider in detail four areas of the intensity map where Boatwright and Bundock (2005) added significantly to the intensity descriptions compiled by Lawson (1908). We show that the distribution of off-fault damage in Sonoma County suggests that the rupture velocity approached the P-wave velocity along Tomales Bay. In contrast, the falloff of intensity with distance from the fault appears approximately constant throughout Mendocino County. The intensity in Humboldt County appears somewhat higher than the intensity in Mendocino County, suggesting that the rupture process at the northern end of the rupture was relatively energetic and that there was directivity consistent with a subsonic rupture velocity on the section of the fault south of Shelter Cove. Finally, we show that the intensity sites added in Santa Cruz County change the intensity distribution so that it decreases gradually along the southeastern section of rupture from Corralitos to San Juan Bautista and implies that the stress release on this section of rupture was relatively low.

Direct visualization of microalgae rupture by ultrasound-driven bubbles

NASA Astrophysics Data System (ADS)

Pommella, Angelo; Harun, Irina; Pouliopoulos, Antonis; Choi, James J.; Hellgardt, Klaus; Garbin, Valeria

2015-11-01

Cell rupture induced by ultrasound is central to applications in biotechnology. For instance, cell disruption is required in the production of biofuels from microalgae (unicellular species of algae). Ultrasound-induced cavitation, bubble collapse and jetting are exploited to induce sufficiently large viscous stresses to cause rupture of the cell membranes. It has recently been shown that seeding the flow with bubbles that act as cavitation nuclei significantly reduces the energy cost for cell processing. However, a fundamental understanding of the conditions for rupture of microalgae in the complex flow fields generated by ultrasound-driven bubbles is currently lacking. We perform high-speed video microscopy to visualize the miscroscale details of the interaction of Chlamydomonas reinhardtii , microalgae of about 10 μm in size, with ultrasound-driven microbubbles of 2-200 μm in diameter. We investigate the efficiency of cell rupture depending on ultrasound frequency and pressure amplitude (from 10 kPa up to 1 MPa), and the resulting bubble dynamics regimes. In particular we compare the efficiency of membrane rupture in the acoustic microstreaming flow induced by linear oscillations, with the case of violent bubble collapse and jetting. V.G. acknowledges partial support from the European Commission (FP7-PEOPLE-2013-CIG), Grant No. 618333.

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.

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.

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.

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.

Demonstration of improved seismic source inversion method of tele-seismic body wave

NASA Astrophysics Data System (ADS)

Yagi, Y.; Okuwaki, R.

2017-12-01

Seismic rupture inversion of tele-seismic body wave has been widely applied to studies of large earthquakes. In general, tele-seismic body wave contains information of overall rupture process of large earthquake, while the tele-seismic body wave is inappropriate for analyzing a detailed rupture process of M6 7 class earthquake. Recently, the quality and quantity of tele-seismic data and the inversion method has been greatly improved. Improved data and method enable us to study a detailed rupture process of M6 7 class earthquake even if we use only tele-seismic body wave. In this study, we demonstrate the ability of the improved data and method through analyses of the 2016 Rieti, Italy earthquake (Mw 6.2) and the 2016 Kumamoto, Japan earthquake (Mw 7.0) that have been well investigated by using the InSAR data set and the field observations. We assumed the rupture occurring on a single fault plane model inferred from the moment tensor solutions and the aftershock distribution. We constructed spatiotemporal discretized slip-rate functions with patches arranged as closely as possible. We performed inversions using several fault models and found that the spatiotemporal location of large slip-rate area was robust. In the 2016 Kumamoto, Japan earthquake, the slip-rate distribution shows that the rupture propagated to southwest during the first 5 s. At 5 s after the origin time, the main rupture started to propagate toward northeast. First episode and second episode correspond to rupture propagation along the Hinagu fault and the Futagawa fault, respectively. In the 2016 Rieti, Italy earthquake, the slip-rate distribution shows that the rupture propagated to up-dip direction during the first 2 s, and then rupture propagated toward northwest. From both analyses, we propose that the spatiotemporal slip-rate distribution estimated by improved inversion method of tele-seismic body wave has enough information to study a detailed rupture process of M6 7 class earthquake.

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.

Ground motion hazard from supershear rupture

USGS Publications Warehouse

Andrews, D.J.

2010-01-01

An idealized rupture, propagating smoothly near a terminal rupture velocity, radiates energy that is focused into a beam. For rupture velocity less than the S-wave speed, radiated energy is concentrated in a beam of intense fault-normal velocity near the projection of the rupture trace. Although confined to a narrow range of azimuths, this beam diverges and attenuates. For rupture velocity greater than the S-wave speed, radiated energy is concentrated in Mach waves forming a pair of beams propagating obliquely away from the fault. These beams do not attenuate until diffraction becomes effective at large distance. Events with supershear and sub-Rayleigh rupture velocity are compared in 2D plane-strain calculations with equal stress drop, fracture energy, and rupture length; only static friction is changed to determine the rupture velocity. Peak velocity in the sub-Rayleigh case near the termination of rupture is larger than peak velocity in the Mach wave in the supershear case. The occurrence of supershear rupture propagation reduces the most intense peak ground velocity near the fault, but it increases peak velocity within a beam at greater distances.

Mortality outcomes of ruptured abdominal aortic aneurysms and rural presentation.

PubMed

Munday, Emily; Walker, Stuart

2016-10-01

Centralisation of vascular surgery services has coincided with a move towards endovascular repair of ruptured abdominal aortic aneurysms with the goal to improve patient outcomes. The aim of this study was to assess the effect of rural presentation and transfer times on survival from ruptured abdominal aortic aneurysm. A retrospective review. All patients presenting with ruptured abdominal aortic aneurysm to public hospitals in Tasmania between July 2006 and April 2013. Demographic data, Glasgow aneurysm score, Hardman index, transfer times, operative technique and 30-day mortality were collected from medical records. Over the study period 127 patients presented to public hospitals in Tasmania with ruptured abdominal aortic aneurysm. A total of 27 presented to north west hospitals where no vascular surgery service is provided (NWRH), 23 to a northern hospital where an intermittent vascular surgery service is provided (LGH) and 77 to the state tertiary vascular surgery service (RHH). Of these, 4 (14.8%) died at NWRH, 6 (26.1%) died at LGH and 43 (55.8%) died at RHH without operation. Of the 35 patients transferred from NWRH and LGH to RHH, 5 died without operation. Median time from presentation to theatre at RHH if transferred from NWRH was 6.25 hours, from the LGH 4.75 hours, compared to 2.75 hours when presenting directly to RHH. Open repair was performed in 41 patients and endovascular repair in 23 patients. Overall 30-day mortality in those treated at RHH was 26.6% (39.0% for open repair, 4.3% for endovascular repair). Mortality for intended operative patients initially presenting to non-RHH hospitals was 33.3% vs. 32.3% for those initially presenting to RHH. p Value 0.93. There was no clinical or statistical disadvantage to rural presentation and transfer for patients presenting with ruptured abdominal aortic aneurysm in Tasmania. Endovascular repair has a role despite long transfer times. © The Author(s) 2015.

The Near-Source Intensity Distribution for the August 24, 2014, South Napa Earthquake

NASA Astrophysics Data System (ADS)

Boatwright, J.; Pickering, A.; Blair, J. L.

2016-12-01

The 2014 Mw=6.0 South Napa earthquake was the largest and most damaging earthquake to occur in the Bay Area since the 1989 Mw=6.9 Loma Prieta earthquake. The City of Napa estimated that the earthquake caused 300 million damage to homes and commercial properties and 58 million to public infrastructure. Over 41,000 reports were entered on the USGS "Did You Feel It?" (DYFI) website: 730 of these reports were located within 15 km of the rupture. Unfortunately, very few geocoded intensities were obtained immediately west and north of the rupture area. In the weeks following the earthquake, we conducted an intensity survey focused on areas poorly sampled by the DYFI reports. 75 sites were surveyed within 15 km of the earthquake rupture. In addition, we checked and manually geocoded many of the DYFI reports, locating 245 reports within 15 km of the rupture that the automated DYFI processing failed to geocode. We combine the survey sites and the newly geocoded DYFI reports with the original geocoded DYFI reports to map and contour the near-source shaking intensity. In addition to imaging the strong shaking (MMI 7.0-8.0) in the City of Napa, we find an area of very strong shaking (MMI 7.5-8.0) to the northwest of the earthquake rupture. This area, marked by ground cracks, damage to modern wood-frame buildings, and reports of people knocked down, coincides with the directivity expected for rupture to the northwest and up dip. The intensities from the survey sites are consistent with the intensities from the DYFI reports, but are much less variable. For DYFI intensities MMI 4-6, this variability could be derived from the 3:20 AM occurrence of the earthquake: some of the effects that the DYFI questionnaire uses to assign these intensities (objects swaying, bushes and trees shaken) cannot be observed in the dark.

Preliminary Results From the Chile-Illapel Aftershock Experiment (CHILLAX)

NASA Astrophysics Data System (ADS)

Roecker, S. W.; Russo, R. M.; Comte, D.; Carrizo, D.; Peyrat, S.; Opazo, T.; Peña, G.; Farrell, M. E.; Moore, J.; Glick, R.; Rodriguez, E. E.

2016-12-01

On September 16, 2015, the Mw 8.3 Illapel earthquake ruptured a segment of the Nazca-South America subduction zone directly to the north of the 2010 Maule Mw 8.8 earthquake. Soon afterwards, a team from the Departamento de Geofisica, University of Chile, installed 18 short period sensors on land above the rupture to record aftershocks. A month later, the network was upgraded and expanded with funding from NSF RAPID to 20 broad band stations, loaned by IRIS PASSCAL. The installation of the Chile-Illapel Aftershock Experiment (CHILLAX) was completed in mid-November, 2015, and will operate until November, 2016. Preliminary analysis of data collected to date indicates an average detection rate of about 1000 locatable aftershocks per month. The combined CHILLAX and Maule aftershock deployments will yield the first modern-instrumentation observations of the zone of along-strike rupture termination that separates these temporally related and spatially adjacent megathrust rupture zones. Additionally, seismic observations of this part of the Nazca subduction zone are relatively sparse, and an aftershock sequence provides an opportunity to fill this gap efficiently. Preliminary analysis of CHILLAX network data revealed unexpected patterns in seismicity down dip from the rupture zone, in the unusual "flat slab" region to the east. Compared to the Maule event, the Illapel rupture apparently generated a more significant increase in seismicity in the 60-200 km depth range, suggesting that it "lit up" the subducted Nazca plate. Although high strain rates due to rupture might extend brittle failure into normally ductile regions, such an effect at these depths by the relatively low magnitude Illapel event is unusual. A perhaps more intriguing result is the frequent occurrence of events at depths significantly below that of the "flat slab". Attribution of this apparent second, deeper slab segment to event mislocations would require unrealistic seismic heterogeneity, We hypothesize that either the subduction of thick, buoyant crust of the Juan Fernandez Ridge has resulted in a slab tear, or that the "flat" seismicity is not occuring within the Nazca slab, but instead within the overriding South American lithosphere. In the latter case, the shallower flat slab earthquakes may represent a nascent delamination event.

Ground motions can help to understand the style of the supershear transition of dynamic ruptures

NASA Astrophysics Data System (ADS)

Bizzarri, A.; Liu, C.

2016-12-01

Supershear earthquakes (which have the propagation speed greater than the S wave speed) are known to leave special signatures in the signals on the fault (fault slip velocity, dynamic traction evolution, energy flux, etc.) and in the generated ground motions. Moreover, two different styles of supershear transition have been identified, that are related to the degree of instability of the fault. In the direct transition (DT) mechanism the rupture at which the rupture front advances (rupture speed) continuously increases from the sub-Rayleigh speed to the terminal speed of P waves, without any jump. On the other hand, in the mother-daughter (MD) mechanism a forbidden zone of rupture speed really exists and a secondary pseudo-rupture is generated ahead of the primary rupture front. Here we found that the also off-fault signals (seismic wavefields) generated by these two mechanisms are rather different. In particular, we show that in that the MD case an enhanced trailing Rayleigh field emerges, which on the contrary has very low amplitudes (or it is even practically absent) in the DT case. Therefore, we show that it is possible to distinguish the style of the supershear transition of an earthquake event by looking at the resulting ground motions. In particular, basing on the results of our numerical simulations, we can conclude that the Denali, Alaska, earthquake was basically controlled by a classical MD mechanism.

Ambivalence and alliance ruptures in cognitive behavioral therapy for generalized anxiety.

PubMed

Hunter, Jennifer A; Button, Melissa L; Westra, Henny A

2014-01-01

Client ambivalence about change (or motivation) is regarded as central to outcomes in cognitive behavioral therapy (CBT). However, little research has been conducted to examine the impact of client ambivalence about change on therapy process variables such as the therapeutic alliance. Given the demonstrated limitations of self-report measures of key constructs such as ambivalence and motivation, the present study instead employed a newly adapted observational measure of client ambivalence. Client statements regarding change (change talk (CT) and counter-change talk (CCT)) were coded in early (session 1 or 2) therapy sessions of CBT for generalized anxiety disorder. The frequency of CT and CCT was then compared between clients who later experienced an alliance rupture with their therapist, and clients who did not. The results showed that clients in dyads who later experienced an alliance rupture expressed significantly more CCT at the outset of therapy than clients who did not later experience an alliance rupture. However, CT utterances did not significantly differ between alliance rupture and no-rupture groups. CCT may strain the alliance because clients expressing higher levels of CCT early in therapy may be less receptive to therapist direction in CBT. Consequently, it is recommended that clients and therapists work together to carefully address these key moments in therapy so as to prevent alliance rupture and preserve client engagement in therapy.

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.

The influence of sex and trauma impact on the rupture site of the ulnar collateral ligament of the thumb.

PubMed

Boesmueller, Sandra; Huf, Wolfgang; Rettl, Gregor; Dahm, Falko; Meznik, Alexander; Muschitz, Gabriela; Kitzinger, Hugo; Bukaty, Adam; Fialka, Christian; Vierhapper, Martin

2017-01-01

Although sex- and gender-specific analyses have been gaining more attention during the last years they have rarely been performed in orthopaedic literature. The primary purpose of this study was to investigate whether for injuries of the UCL the specific location of the rupture is influenced by sex. A secondary study question addressed the sex-independent effect of trauma intensity on the rupture site of the UCL. This study is a retrospective analysis of all patients with either a proximal or distal bony avulsion or with a mid-substance tear or ligament avulsion of the UCL treated surgically between 1992 and 2015 at two level-I trauma centres. Trauma mechanisms leading to the UCL injury were classified into the following categories: (1) blunt trauma (i.e., strains), (2) low-velocity injuries (e.g., fall from standing height, assaults), and (3) high-velocity injuries (e.g., sports injuries, motor vehicle accidents). After reviewing the surgical records, patients were divided into three groups, depending upon the ligament rupture site: (1) mid-substance tears, (2) proximal ligament or bony avulsions and (3) distal ligament or bony avulsions. Dependencies between the specific rupture site and the explanatory variables (sex, age, and trauma intensity) were evaluated using χ2 test and logistic regression analysis. In total, 1582 patients (1094 males, 488 females) met the inclusion criteria. Mean age was 41 years (range: 9-90 years). Taking into account the effects of sex on trauma intensity (p<0.001) and of trauma intensity on rupture site (p<0.001), mid-substance tears occurred more frequently in women, whereas men were more prone to distal ligament or bony avulsions (p<0.001). In other words, sex and rupture site correlated due to the effects of sex on trauma intensity and of trauma intensity on rupture site, but taking into account those effects there still was a significant effect of sex on rupture site. The results of this study demonstrate that with regression analysis both sex and trauma intensity allow to predict rupture site in UCL injuries.

The influence of sex and trauma impact on the rupture site of the ulnar collateral ligament of the thumb

PubMed Central

Huf, Wolfgang; Rettl, Gregor; Dahm, Falko; Meznik, Alexander; Muschitz, Gabriela; Kitzinger, Hugo; Bukaty, Adam; Fialka, Christian; Vierhapper, Martin

2017-01-01

Purpose and hypothesis Although sex- and gender-specific analyses have been gaining more attention during the last years they have rarely been performed in orthopaedic literature. The primary purpose of this study was to investigate whether for injuries of the UCL the specific location of the rupture is influenced by sex. A secondary study question addressed the sex-independent effect of trauma intensity on the rupture site of the UCL. Methods This study is a retrospective analysis of all patients with either a proximal or distal bony avulsion or with a mid-substance tear or ligament avulsion of the UCL treated surgically between 1992 and 2015 at two level-I trauma centres. Trauma mechanisms leading to the UCL injury were classified into the following categories: (1) blunt trauma (i.e., strains), (2) low-velocity injuries (e.g., fall from standing height, assaults), and (3) high-velocity injuries (e.g., sports injuries, motor vehicle accidents). After reviewing the surgical records, patients were divided into three groups, depending upon the ligament rupture site: (1) mid-substance tears, (2) proximal ligament or bony avulsions and (3) distal ligament or bony avulsions. Dependencies between the specific rupture site and the explanatory variables (sex, age, and trauma intensity) were evaluated using χ2 test and logistic regression analysis. Results In total, 1582 patients (1094 males, 488 females) met the inclusion criteria. Mean age was 41 years (range: 9–90 years). Taking into account the effects of sex on trauma intensity (p<0.001) and of trauma intensity on rupture site (p<0.001), mid-substance tears occurred more frequently in women, whereas men were more prone to distal ligament or bony avulsions (p<0.001). In other words, sex and rupture site correlated due to the effects of sex on trauma intensity and of trauma intensity on rupture site, but taking into account those effects there still was a significant effect of sex on rupture site. Conclusions The results of this study demonstrate that with regression analysis both sex and trauma intensity allow to predict rupture site in UCL injuries. PMID:28738083

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.

Poly Implant Prothèse (PIP) incidence of rupture: a retrospective MR analysis in 64 patients.

PubMed

Scotto di Santolo, Mariella; Cusati, Bianca; Ragozzino, Alfonso; Dell'Aprovitola, Nicoletta; Acquaviva, Alessandra; Altiero, Michele; Accurso, Antonello; Riccardi, Albina; Imbriaco, Massimo

2014-12-01

The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) features of Poly Implant Prothèse (PIP) hydrogel implants in a group of 64 patients and to assess the incidence of rupture, compared to other clinical trials. In this double-center study, we retrospectively reviewed the data sets of 64 consecutive patients (mean age, 43±9 years, age range, 27-65 years), who underwent breast MRI examinations, between January 2008 and October 2013, with suspected implant rupture on the basis of clinical assessment or after conventional imaging examination (either mammography or ultrasound). All patients had undergone breast operation with bilateral textured cohesive gel PIP implant insertion for aesthetic reasons. The mean time after operation was 8 years (range, 6-14 years). No patients reported history of direct trauma to their implants. At the time of clinical examination, 41 patients were asymptomatic, 16 complained of breast tenderness and 7 had clinical evidence of rupture. Normal findings were observed in 15 patients. In 26 patients there were signs of mild collapse, with associated not significant peri-capsular fluid collections and no evidence of implant rupture; in 23 patients there was suggestion of implant rupture, according to breast MRI leading to an indication for surgery. In particular, 14 patients showed intra-capsular rupture, with associated evidence of the linguine sign in all cases; the keyhole sign and the droplet signs were observed in 6 cases. In 9 patients there was evidence of extra-capsular rupture, with presence of axillary collections (siliconomas) in 7 cases and peri-prosthetic and mediastinal cavity siliconomas, in 5 cases. The results of this double center retrospective study, confirm the higher incidence (36%) of prosthesis rupture observed with the PIP implants, compared to other breast implants.

Evaluation of directionally solidified eutectic superalloys for turbine blade applications

NASA Technical Reports Server (NTRS)

Henry, M. E.; Jackson, M. R.; Walter, J. L.

1978-01-01

Alloys from the following systems were selected for property evaluation: (1) gamma/gamma-Mo (Ni-base, rods of Mo); (2) gamma-beta (Ni-base, lamellae or rods of (Ni, Fe/Co Al); and (3) gamma-gamma (Ni-base rods of Ni3Al gamma). The three alloys were subjected to longitudinal and transverse tensile and rupture tests from 750 C to 1100 C, longitudinal shear strength was measured at several temperatures, resistance to thermal cycling to 1150 C was determined, cyclic oxidation resistance was evaluated at 750 C and 1100 C, and each system was directionally solidified in an alumina shell mold turbine shape to evaluate mold/metal reactivity. The gamma/gamma Mo system has good rupture resistance, transverse properties and processability, and is a high potential system for turbine blades. The gamma-beta system has good physical properties and oxidation resistance, and is a potential system for turbine vanes. The gamma-gamma system has good high temperature rupture resistance and requires further exploratory research.

Tectonic position and geological manifestations of the Mogod (Central Mongolia), January 5, 1967, earthquake (a view after 40 years)

USGS Publications Warehouse

Rogozhin, E.A.; Imaev, V.S.; Smekalin, O.P.; Schwartz, D.P.

2008-01-01

The earthquake source, reaching the surface in the form of an extended system of faults, encompassed the N-S and NW-SE planes of two large faults near their juncture zone. A revised seismotectonic study of the system of coseismic ruptures performed after many years revealed a complex structure of primary coseismic ruptures in the juncture area of fault branches of different directions. In addition to the two major faults, the juncture zone consists of intersecting or parallel branches of both structural directions. The trench study and detailed mapping of the shallow structure of the seismic rupture characterizes it as a right-lateral-thrust fault on the N-S branch and a strike-slip-reverse fault on the NW-SE branch. Results of our paleoseismogeological study indicate that equally strong earthquakes are likely to have occurred in the same seismic source in the past (about 8000 and 160 years ago). ?? Pleiades Publishing, Ltd. 2008.

Source Complexity of an Injection Induced Event: The 2016 Mw 5.1 Fairview, Oklahoma Earthquake

NASA Astrophysics Data System (ADS)

López-Comino, J. A.; Cesca, S.

2018-05-01

Complex rupture processes are occasionally resolved for weak earthquakes and can reveal a dominant direction of the rupture propagation and the presence and geometry of main slip patches. Finding and characterizing such properties could be important for understanding the nucleation and growth of induced earthquakes. One of the largest earthquakes linked to wastewater injection, the 2016 Mw 5.1 Fairview, Oklahoma earthquake, is analyzed using empirical Green's function techniques to reveal its source complexity. Two subevents are clearly identified and located using a new approach based on relative hypocenter-centroid location. The first subevent has a magnitude of Mw 5.0 and shows the main rupture propagated toward the NE, in the direction of higher pore pressure perturbations due to wastewater injection. The second subevent appears as an early aftershock with lower magnitude, Mw 4.7. It is located SW of the mainshock in a region of increased Coulomb stress, where most aftershocks relocated.

Pseudo-dynamic source characterization accounting for rough-fault effects

NASA Astrophysics Data System (ADS)

Galis, Martin; Thingbaijam, Kiran K. S.; Mai, P. Martin

2016-04-01

Broadband ground-motion simulations, ideally for frequencies up to ~10Hz or higher, are important for earthquake engineering; for example, seismic hazard analysis for critical facilities. An issue with such simulations is realistic generation of radiated wave-field in the desired frequency range. Numerical simulations of dynamic ruptures propagating on rough faults suggest that fault roughness is necessary for realistic high-frequency radiation. However, simulations of dynamic ruptures are too expensive for routine applications. Therefore, simplified synthetic kinematic models are often used. They are usually based on rigorous statistical analysis of rupture models inferred by inversions of seismic and/or geodetic data. However, due to limited resolution of the inversions, these models are valid only for low-frequency range. In addition to the slip, parameters such as rupture-onset time, rise time and source time functions are needed for complete spatiotemporal characterization of the earthquake rupture. But these parameters are poorly resolved in the source inversions. To obtain a physically consistent quantification of these parameters, we simulate and analyze spontaneous dynamic ruptures on rough faults. First, by analyzing the impact of fault roughness on the rupture and seismic radiation, we develop equivalent planar-fault kinematic analogues of the dynamic ruptures. Next, we investigate the spatial interdependencies between the source parameters to allow consistent modeling that emulates the observed behavior of dynamic ruptures capturing the rough-fault effects. Based on these analyses, we formulate a framework for pseudo-dynamic source model, physically consistent with the dynamic ruptures on rough faults.

Simultaneous bilateral Achilles tendon ruptures associated with statin medication despite regular rock climbing exercise.

PubMed

Carmont, Michael R; Highland, Adrian M; Blundell, Christopher M; Davies, Mark B

2009-11-01

Ruptures of the Achilles tendon are common however simultaneous ruptures occur less frequently. Eccentric loading exercise programmes have been used to successfully treat Achilles tendinopathy. We report a case of simultaneous bilateral Achilles tendon rupture in a patient predisposed to rupture due to longstanding raised serum lipoprotein and recently introduced therapeutic statin medication. The patient was also a keen rock climber and had regularly undertaken loading exercise. This case illustrates that the therapeutic effect of mixed loading exercises for the Achilles tendon may not be adequate to overcome the predisposition to rupture caused by hyperlipidaemia and statin medication.

Room and Elevated Temperature Tensile Properties of Single Tow Hi-Nicalon, Carbon Interphase, CVI SiC Matrix Minicomposites

NASA Technical Reports Server (NTRS)

Martinez-Fernandez, J.; Morscher, G. N.

2000-01-01

Single tow Hi-Nicalon(TM), C interphase, CVI SiC matrix minicomposites were tested in tension at room temperature, 700 C, 950 C, and 1200 C in air. Monotonic loading with modal acoustic emission monitoring was performed at room temperature in order to determine the dependence of matrix cracking on applied load. Modal acoustic emission was shown to correlate directly with the number of matrix cracks formed. Elevated temperature constant load stress-rupture and low-cycle fatigue experiments were performed on precracked specimens. The elevated temperature rupture behavior was dependent on the precrack stress, the lower precrack stress resulting in longer rupture life for a given stress. It was found that the rupture lives of C-interphase Hi-Nicalon(TM) minicomposites were superior to C-interphase Ceramic Grade Nicalon(TM) minicomposites and inferior to those of BN-interphase Hi-Nicalon(TM) minicomposites.

Testing geomorphology-derived rupture histories against the paleoseismic record of the southern San Andreas fault

USGS Publications Warehouse

Scharer, Katherine M.; Weldon, Ray; Bemis, Sean

2016-01-01

Evidence for the 340-km-long Fort Tejon earthquake of 1857 is found at each of the high-resolution paleoseismic sites on the southern San Andreas Fault. Using trenching data from these sites, we find that the assemblage of dated paleoearthquakes recurs quasi-periodically (coefficient of variation, COV, of 0.6, Biasi, 2013) and requires ~80% of ruptures were shorter than the 1857 rupture with an average of Mw7.5. In contrast, paleorupture lengths reconstructed from preserved geomorphic offsets extracted from lidar are longer and have repeating displacements that are quite regular (COV=0.2; Zielke et al., 2015). Direct comparison shows that paleoruptures determined from geomorphic offset populations cannot be reconciled with dated paleoearthquakes. Our study concludes that the 1857 rupture was larger than average, average displacements must be < 5 m, and suggests that fault geometry may play a role in fault behavior.

Globe rupture with post cataract-surgery safety sunglasses.

PubMed

Brooks, Clifford W; Howard, Robert C; Lyons, Robert A; Reilly, Charles D

2010-07-01

We report a case of globe rupture associated with the use of post cataract-surgery protective eyewear. The patient had routine cataract surgery 3 months before presentation and had adapted his post cataract-surgery glasses to use on the tennis court. He experienced a large posterior globe rupture after falling directly onto his face during a match. Spectacle torsion is the suspected biomechanical process that led to the rupture. We conclude that although the glasses given to many patients after cataract surgery are protective for most low-impact injuries, patients should be aware they are not designed for activities with a risk for significant impact. Patients should also be counseled to use protective eyewear specifically designed and approved for the sport or activity in which they participate. No author has a financial or proprietary interest in any material or method mentioned. Published by Elsevier Inc.

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.

Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake

USGS Publications Warehouse

Parsons, T.; Yeats, R.S.; Yagi, Y.; Hussain, A.

2006-01-01

We calculated static stress changes from the devastating M = 7.6 earthquake that shook Kashmir on 8 October, 2005. We mapped Coulomb stress change on target fault planes oriented by assuming a regional compressional stress regime with greatest principal stress directed orthogonally to the mainshock strike. We tested calculation sensitivity by varying assumed stress orientations, target-fault friction, and depth. Our results showed no impact on the active Salt Range thrust southwest of the rupture. Active faults north of the Main Boundary thrust near Peshawar fall in a calculated stress-decreased zone, as does the Raikot fault zone to the northeast. We calculated increased stress near the rupture where most aftershocks occurred. The greatest increase to seismic hazard is in the Indus-Kohistan seismic zone near the Indus River northwest of the rupture termination, and southeast of the rupture termination near the Kashmir basin.

GPS source solution of the 2004 Parkfield earthquake.

PubMed

Houlié, N; Dreger, D; Kim, A

2014-01-17

We compute a series of finite-source parameter inversions of the fault rupture of the 2004 Parkfield earthquake based on 1 Hz GPS records only. We confirm that some of the co-seismic slip at shallow depth (<5 km) constrained by InSAR data processing results from early post-seismic deformation. We also show 1) that if located very close to the rupture, a GPS receiver can saturate while it remains possible to estimate the ground velocity (~1.2 m/s) near the fault, 2) that GPS waveforms inversions constrain that the slip distribution at depth even when GPS monuments are not located directly above the ruptured areas and 3) the slip distribution at depth from our best models agree with that recovered from strong motion data. The 95(th) percentile of the slip amplitudes for rupture velocities ranging from 2 to 5 km/s is ~55 ± 6 cm.

GPS source solution of the 2004 Parkfield earthquake

PubMed Central

Houlié, N.; Dreger, D.; Kim, A.

2014-01-01

We compute a series of finite-source parameter inversions of the fault rupture of the 2004 Parkfield earthquake based on 1 Hz GPS records only. We confirm that some of the co-seismic slip at shallow depth (<5 km) constrained by InSAR data processing results from early post-seismic deformation. We also show 1) that if located very close to the rupture, a GPS receiver can saturate while it remains possible to estimate the ground velocity (~1.2 m/s) near the fault, 2) that GPS waveforms inversions constrain that the slip distribution at depth even when GPS monuments are not located directly above the ruptured areas and 3) the slip distribution at depth from our best models agree with that recovered from strong motion data. The 95th percentile of the slip amplitudes for rupture velocities ranging from 2 to 5 km/s is ~55 ± 6 cm. PMID:24434939

Creep rupture strength of activated-TIG welded 316L(N) stainless steel

NASA Astrophysics Data System (ADS)

Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

2011-06-01

316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower δ-ferrite content, alignment of columnar grain with δ-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

The effect of compliant prisms on subduction zone earthquakes and tsunamis

NASA Astrophysics Data System (ADS)

Lotto, Gabriel C.; Dunham, Eric M.; Jeppson, Tamara N.; Tobin, Harold J.

2017-01-01

Earthquakes generate tsunamis by coseismically deforming the seafloor, and that deformation is largely controlled by the shallow rupture process. Therefore, in order to better understand how earthquakes generate tsunamis, one must consider the material structure and frictional properties of the shallowest part of the subduction zone, where ruptures often encounter compliant sedimentary prisms. Compliant prisms have been associated with enhanced shallow slip, seafloor deformation, and tsunami heights, particularly in the context of tsunami earthquakes. To rigorously quantify the role compliant prisms play in generating tsunamis, we perform a series of numerical simulations that directly couple dynamic rupture on a dipping thrust fault to the elastodynamic response of the Earth and the acoustic response of the ocean. Gravity is included in our simulations in the context of a linearized Eulerian description of the ocean, which allows us to model tsunami generation and propagation, including dispersion and related nonhydrostatic effects. Our simulations span a three-dimensional parameter space of prism size, prism compliance, and sub-prism friction - specifically, the rate-and-state parameter b - a that determines velocity-weakening or velocity-strengthening behavior. We find that compliant prisms generally slow rupture velocity and, for larger prisms, generate tsunamis more efficiently than subduction zones without prisms. In most but not all cases, larger, more compliant prisms cause greater amounts of shallow slip and larger tsunamis. Furthermore, shallow friction is also quite important in determining overall slip; increasing sub-prism b - a enhances slip everywhere along the fault. Counterintuitively, we find that in simulations with large prisms and velocity-strengthening friction at the base of the prism, increasing prism compliance reduces rather than enhances shallow slip and tsunami wave height.

Surface fault rupture during the Mw 7.8 Kaikoura earthquake, New Zealand, with specific comment on the Kekerengu Fault - one of the country's fastest slipping onland active faults

NASA Astrophysics Data System (ADS)

Van Dissen, Russ; Little, Tim

2017-04-01

The Mw 7.8 Kaikoura earthquake of 14 November, 2016 (NZDT) was a complex event. It involved ground-surface (or seafloor) fault rupture on at least a dozen onland or offshore faults, and subsurface rupture on a handful of additional faults. Most of the surface ruptures involved previously known (or suspected) active faults, as well as surface rupture on at least two hitherto unrecognised active faults. The southwest to northeast extent of surface fault rupture, as generalised by two straight-line segments, is approximately 180 km, though this is a minimum for the collective length of surface rupture due to multiple overlapping faults with various orientations. Surface rupture displacements on specific faults involved in the Kaikoura Earthquake span approximately two orders of magnitude. For example, maximum surface displacement on the Heaver's Creek Fault is cm- to dm-scale in size; whereas, maximum surface displacement on the nearby Kekerengu Fault is approximately 10-12 m (predominantly in a dextral sense). The Kekerengu Fault has a Late Pleistocene slip-rate rate of 20-26 mm/yr, and is possibly the second fastest slipping onland fault in New Zealand, behind the Alpine Fault. Located in the northeastern South Island of New Zealand, the Kekerengu Fault - along with the Hope Fault to the southwest and the Needles Fault offshore to the northeast - comprise the fastest slipping elements of the Pacific-Australian plate boundary in this part of the country. In January 2016 (about ten months prior to the Kaikoura earthquake) three paleo-earthquake investigation trenches were excavated across pronounced traces of the Kekerengu Fault at two locations. These were the first such trenches dug and evaluated across the fault. All three trenches displayed abundant evidence of past surface fault ruptures (three surface ruptures in the last approximately 1,200 years, four now including the 2016 rupture). An interesting aspect of the 2016 rupture is that two of the trenches received surface fault rupture, and are now dextrally offset by about 9 m, while the third trench did not have any 2016 surface rupture pass through it. In this instance, ground-surface rupture along this trace of the fault died out within tens of metres of the trench. Another salient aspect of the Kaikoura earthquake is that the determined (or estimated) recurrence intervals of the faults that ruptured the ground surface vary by an order of magnitude or more. This strongly implies that the ensemble of faults that ruptured with the Kekerengu Fault in the 2016 earthquake has not always been the same for past earthquakes. Possible reasons for this could include the state of stress at the time of a specific earthquake, the direction of rupture propagation, and whether or not rupture on one fault system cascades into rupture on another as is suspected to have happened in the Kaikoura earthquake.

Ground-motion signature of dynamic ruptures on rough faults

NASA Astrophysics Data System (ADS)

Mai, P. Martin; Galis, Martin; Thingbaijam, Kiran K. S.; Vyas, Jagdish C.

2016-04-01

Natural earthquakes occur on faults characterized by large-scale segmentation and small-scale roughness. This multi-scale geometrical complexity controls the dynamic rupture process, and hence strongly affects the radiated seismic waves and near-field shaking. For a fault system with given segmentation, the question arises what are the conditions for producing large-magnitude multi-segment ruptures, as opposed to smaller single-segment events. Similarly, for variable degrees of roughness, ruptures may be arrested prematurely or may break the entire fault. In addition, fault roughness induces rupture incoherence that determines the level of high-frequency radiation. Using HPC-enabled dynamic-rupture simulations, we generate physically self-consistent rough-fault earthquake scenarios (M~6.8) and their associated near-source seismic radiation. Because these computations are too expensive to be conducted routinely for simulation-based seismic hazard assessment, we thrive to develop an effective pseudo-dynamic source characterization that produces (almost) the same ground-motion characteristics. Therefore, we examine how variable degrees of fault roughness affect rupture properties and the seismic wavefield, and develop a planar-fault kinematic source representation that emulates the observed dynamic behaviour. We propose an effective workflow for improved pseudo-dynamic source modelling that incorporates rough-fault effects and its associated high-frequency radiation in broadband ground-motion computation for simulation-based seismic hazard assessment.

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.

Steady-state propagation speed of rupture fronts along one-dimensional frictional interfaces.

PubMed

Amundsen, David Skålid; Trømborg, Jørgen Kjoshagen; Thøgersen, Kjetil; Katzav, Eytan; Malthe-Sørenssen, Anders; Scheibert, Julien

2015-09-01

The rupture of dry frictional interfaces occurs through the propagation of fronts breaking the contacts at the interface. Recent experiments have shown that the velocities of these rupture fronts range from quasistatic velocities proportional to the external loading rate to velocities larger than the shear wave speed. The way system parameters influence front speed is still poorly understood. Here we study steady-state rupture propagation in a one-dimensional (1D) spring-block model of an extended frictional interface for various friction laws. With the classical Amontons-Coulomb friction law, we derive a closed-form expression for the steady-state rupture velocity as a function of the interfacial shear stress just prior to rupture. We then consider an additional shear stiffness of the interface and show that the softer the interface, the slower the rupture fronts. We provide an approximate closed form expression for this effect. We finally show that adding a bulk viscosity on the relative motion of blocks accelerates steady-state rupture fronts and we give an approximate expression for this effect. We demonstrate that the 1D results are qualitatively valid in 2D. Our results provide insights into the qualitative role of various key parameters of a frictional interface on its rupture dynamics. They will be useful to better understand the many systems in which spring-block models have proved adequate, from friction to granular matter and earthquake dynamics.

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.

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

Neck curve polynomials in neck rupture model

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

Kurniadi, Rizal; Perkasa, Yudha S.; Waris, Abdul

2012-06-06

The Neck Rupture Model is a model that explains the scission process which has smallest radius in liquid drop at certain position. Old fashion of rupture position is determined randomly so that has been called as Random Neck Rupture Model (RNRM). The neck curve polynomials have been employed in the Neck Rupture Model for calculation the fission yield of neutron induced fission reaction of {sup 280}X{sub 90} with changing of order of polynomials as well as temperature. The neck curve polynomials approximation shows the important effects in shaping of fission yield curve.

In Vivo Molecular Imaging of Acute and Subacute Thrombosis Using a Fibrin-Binding Magnetic Resonance Imaging Contrast Agent

PubMed Central

Botnar, René M.; Perez, Alexandra S.; Witte, Sonia; Wiethoff, Andrea J.; Laredo, James; Hamilton, James; Quist, William; Parsons, Edward C.; Vaidya, Anand; Kolodziej, Andrew; Barrett, John A.; Graham, Philip B.; Weisskoff, Robert M.; Manning, Warren J.; Johnstone, Michael T.

2010-01-01

Background Plaque rupture with subsequent thrombosis is recognized as the underlying pathophysiology of most acute coronary syndromes and stroke. Thus, direct thrombus visualization may be beneficial for both diagnosis and guidance of therapy. We sought to test the feasibility of direct imaging of acute and subacute thrombosis using MRI together with a novel fibrin-binding gadolinium-labeled peptide, EP-1873, in an experimental animal model of plaque rupture and thrombosis. Methods and Results Fifteen male New Zealand White rabbits (weight, ≈3.5 kg) were made atherosclerotic by feeding a high-cholesterol diet after endothelial aortic injury. Plaque rupture was then induced with the use of Russell’s viper venom (RVV) and histamine. Subsequently, MRI of the subrenal aorta was performed before RVV, after RVV, and after EP-1873. Histology was performed on regions suggested by MRI to contain thrombus. Nine rabbits (60%) developed plaque rupture and thrombus, including 25 thrombi visually apparent on MRI as “hot spots” after injection of EP-1873. Histological correlation confirmed all 25 thrombi (100%), with no thrombi seen in the other regions of the aorta. In the remaining 6 rabbits (control) without plaque rupture, no thrombus was observed on the MR images or on histology. Conclusions We demonstrate the feasibility of in vivo “molecular” MRI for the detection of acute and subacute thrombosis using a novel fibrin-binding MRI contrast agent in an animal model of atherosclerosis and acute/subacute thrombosis. Potential clinical applications include thrombus detection in acute coronary syndromes and stroke. PMID:15066940

Some Key Features of the Strong-Motion Data from the M 6.0 Parkfield, California, Earthquake of 28 September 2004

USGS Publications Warehouse

Shakal, A.; Haddadi, H.; Graizer, V.; Lin, K.; Huang, M.

2006-01-01

The 2004 Parkfield, California, earthquake was recorded by an extensive set of strong-motion instruments well positioned to record details of the motion in the near-fault region, where there has previously been very little recorded data. The strong-motion measurements obtained are highly varied, with significant variations occurring over only a few kilometers. The peak accelerations in the near fault region range from 0.13g to over 1.8g (one of the highest acceleration recorded to date, exceeding the capacity of the recording instrument The largest accelerations occurred near the northwest end of the inferred rupture zone. These motions are consistent with directivity for a fault rupturing from the hypocenter near Gold Hill toward the northwest. However, accelerations up to 0.8g were also observed in the opposite direction, at the south end of the Cholame Valley near Highway 41, consistent with bilateral rupture, with rupture southeast of the hypocenter. Several stations near and over the rupturing fault recorded relatively weak motions, consistent with seemingly paradoxical observations of low shaking damage near strike-slip faults. This event had more ground-motion observations within 10 km of the fault than many other earthquakes combined. At moderate distances peak horizontal ground acceleration (PGA) values dropped off more rapidly with distance than standard relationships. At close-in distance the wide variation of PGA suggests a distance-dependent sigma may be important to consider. The near-fault ground-motion variation is greater than that assumed in ShakeMap interpolations, based on the existing set of observed data. Higher density of stations near faults may be the only means in the near future to reduce uncertainty in the interpolations. Outside of the near-fault zone the variance is closer to that assumed. This set of data provides the first case where near-fault radiation has been observed at an adequate number of stations around the fault to allow detailed study of the fault-normal and fault-parallel motion and the near-field S-wave radiation. The fault-normal motions are significant, but they are not large at the central part of the fault, away from the ends. The fault-normal and fault-parallel motions drop off quite rapidly with distance from the fault. Analysis of directivity indicates increased values of peak velocity in the rupture direction. No such dependence is observed in the peak acceleration, except for stations close to the strike of the fault near and beyond the ends of the faulting.

Study Of The Rupture Process Of The 2015 Mw7.8 Izu-Bonin Earthquake And Its Implication To Deep-Focus Earthquake Genesis.

NASA Astrophysics Data System (ADS)

Jian, P. R.; Hung, S. H.; Meng, L.

2015-12-01

On May 30, 2015, a major Mw7.8 great deep earthquake occurred at the base of the mantle transition zone (MTZ), approximately 680 km deep within the Pacific Plate which subducts westward under the Philippine Sea Plate along the Izu-Bonin trench. A global P wave tomographic image indicates that a tabular high-velocity structure delineated by ~1% faster than the ambient mantle plunges nearly vertical to a depth at most 600 km and afterword flattens and stagnates within the MTZ. Almost all the deep earthquakes in this region are clustered inside this fast anomaly corresponding to the cold core of the subducting slab. Those occurring at depth between 400~500 km close to the hinge of the bending slab show down-dip compressional focal mechanisms and reflect episodic release of compressive strain accumulated in the slab. The 2015 deep event, however, separated from the others, occurred uniquely near the base of the lithosphere with a down-dip extension mechanism, consistent with the notion that the outer portion of the folded slab experiences extensional bending stress. Here we perform a 3D MUSIC back-projection (BP) rupture imaging for this isolated deep event using P and pP waveforms individually from the European, North American and Australian array data. By integrating P- and pP- BP images in frequencies of 0.1-1 Hz obtained from three array observations with different azimuth, we first ascertain the most possible fault plan is the SW-dipping subhorizontal one. Then, from back-projecting higher frequency waveforms at 1-1.5 Hz onto the obtained fault plane, we find the rupture initially propagates slowly along the strike (SW-direction), and makes a turn to the NNW-direction at ~12s after the onset of rupture. The MUSIC psudospectrum over totally 20s rupture duration reveals that most seismic energy radiation takes place at the initial 8s of the first rupture along the strike, 10-15 km long region, while the along-updip second rupture lasting for 6-10s has a rupture length of 15-20 km and weaker radiated energy. The overall rupture speed is about 1.5-2 km/s. As it rarely struck the area close to the outer periphery of the slab under the condition of relatively high-temperature and downdip extension, thermally-induced shear instability may play an important role in the genesis of this deep-focus earthquake.

EGF Search for Compound Source Time Functions in Microearthquakes

NASA Astrophysics Data System (ADS)

Ampuero, J.; Rubin, A. M.

2003-12-01

Numerical simulations of stopping ruptures on bimaterial interfaces seem to indicate a pronounced asymmetry in the time it takes to reach the peak Coulomb stress shortly beyond the rupture ends. For the rupture front moving in the direction of slip of the stiffer medium, the timescale is controlled by the arrival of stopping phases from the opposite side of the crack, but for the opposite rupture front this timescale is controlled by the much shorter-duration tensile stress pulse that moves in front of the crack tip as it slows down. This behavior may have implications for rupture complexity on bimaterial interfaces. In addition to observing an asymmetry in aftershock occurrence on the San Andreas fault, Rubin and Gillard (2000) noted that for all 5 of the compound earthquakes they observed in a cluster of 72 events, the second subevent occurred to the NW of the first (that is, near the rupture front moving in the direction of slip of the stiffer medium). They suggested that these 5``second events'' were simply examples of ``early aftershocks'' which also occur preferentially to the NW; however, the fact that these 5 earthquakes could not be recognized as compound at stations located to the SE indicates that the second event actually occurred on the timescale of the passage of the dynamic stress waves. Thus, observations of asymmetry in rupture complexity may form an independent dataset, complimentary to observations of aftershock asymmetry, for constraining models of rupture on bimaterial interfaces. Microseismicity recorded on dense seismological networks has proved interesting for earthquake physics because the high number of events allows one to gain statistical insight into the observed source properties. However, microearthquakes are usually so small that the range of methods that can be applied to their analysis is limited and of low resolution. To address the questions raised above we would like to characterize the source time functions (STF) of a large number of microearthquakes, in particular the statistics of compound events and the possible asymmetry of their spatial distribution. We will show results of the systematic application of empirical Green's function deconvolution methods to a large dataset from the Parkfield HRSN. On the methodological side the performance and robustness of various deconvolution schemes is tested. These range from trivially stabilized spectral division to projected Landweber and blind deconvolution. Use is also made of the redundance available in highly clustered seismicity with many similar seismograms. The observations will be interpreted in the light of recent numerical simulations of dynamic rupture on bimaterial interfaces (see abstract of Rubin and Ampuero).

Effect of reduction of strategic Columbium addition in 718 Alloy on the structure and properties

NASA Technical Reports Server (NTRS)

Ziegler, K. R.; Wallace, J. F.

1985-01-01

A series of alloys was developed having a base composition similar to Inconel 718, with reduced Cb levels of 3.00 and 1.10 wt% Cb. Substitutions of 3.0% W, 3.0W + 0.9V or Mo increased from 3.0% to 5.8% were made for the Cb in these alloys. Two additional alloys, one containing 3.49% Cb and 1.10% Ti and another containing 3.89% Cb and 1.29% Ti were also studied. Tensile properties at rooom and elevated temperatures, stress-rupture tests, and an analysis of extracted phases were carried out for each of the alloys. Additions of solid solution elements to a reduced Cb alloy had no significant effect on the properties of the alloys under either process condition. The solution and age alloys with substitutions of 1.27% i at 3.89% Cb had tensile properties similar top hose of the original alloy and stress-rupture properties superior to the original alloy. The improved stress-rupture properties were the result of significant precipitation of Ni3Ti-gamma prime in the alloy, which is more stable than gamma' at the elevated temperatures. At lower temperatures, the new alloy benefits from gamma' strengthening. With more precise control and proper processing, the reduced Cb direct-age alloy could substitute for Alloy 718 in high strength applications.

Macroscopic Source Properties from Dynamic Rupture Styles in Plastic Media

NASA Astrophysics Data System (ADS)

Gabriel, A.; Ampuero, J. P.; Dalguer, L. A.; Mai, P. M.

2011-12-01

High stress concentrations at earthquake rupture fronts may generate an inelastic off-fault response at the rupture tip, leading to increased energy absorption in the damage zone. Furthermore, the induced asymmetric plastic strain field in in-plane rupture modes may produce bimaterial interfaces that can increase radiation efficiency and reduce frictional dissipation. Off-fault inelasticity thus plays an important role for realistic predictions of near-fault ground motion. Guided by our previous studies in the 2D elastic case, we perform rupture dynamics simulations including rate-and-state friction and off-fault plasticity to investigate the effects on the rupture properties. We quantitatively analyze macroscopic source properties for different rupture styles, ranging from cracks to pulses and subshear to supershear ruptures, and their transitional mechanisms. The energy dissipation due to off-fault inelasticity modifies the conditions to obtain each rupture style and alters macroscopic source properties. We examine apparent fracture energy, rupture and healing front speed, peak slip and peak slip velocity, dynamic stress drop and size of the process and plastic zones, slip and plastic seismic moment, and their connection to ground motion. This presentation focuses on the effects of rupture style and off-fault plasticity on the resulting ground motion patterns, especially on characteristic slip velocity function signatures and resulting seismic moments. We aim at developing scaling rules for equivalent elastic models, as function of background stress and frictional parameters, that may lead to improved "pseudo-dynamic" source parameterizations for ground-motion calculation. Moreover, our simulations provide quantitative relations between off-fault energy dissipation and macroscopic source properties. These relations might provide a self-consistent theoretical framework for the study of the earthquake energy balance based on observable earthquake source parameters.

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.

Effects of neem oil (Azadirachta indica A. Juss) on midgut cells of predatory larvae Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae).

PubMed

Scudeler, Elton Luiz; dos Santos, Daniela Carvalho

2013-01-01

The effects of ingested neem oil, a botanical insecticide obtained from the seeds of the neem tree, Azadirachta indica, on the midgut cells of predatory larvae Ceraeochrysa claveri were analyzed. C. claveri were fed on eggs of Diatraea saccharalis treated with neem oil at a concentration of 0.5%, 1% and 2% during throughout the larval period. Light and electron microscopy showed severe damages in columnar cells, which had many cytoplasmic protrusions, clustering and ruptured of the microvilli, swollen cells, ruptured cells, dilatation and vesiculation of rough endoplasmic reticulum, development of smooth endoplasmic reticulum, enlargement of extracellular spaces of the basal labyrinth, intercellular spaces and necrosis. The indirect ingestion of neem oil with prey can result in severe alterations showing direct cytotoxic effects of neem oil on midgut cells of C. claveri larvae. Therefore, the safety of neem oil to non-target species as larvae of C. claveri was refuted, thus the notion that plants derived are safer to non-target species must be questioned in future ecotoxicological studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Linkages Between the Megathrust and Upper-plate Deformation: Lessons From the Deformational Dichotomy of the 2016 Kaikoura New Zealand Earthquake

NASA Astrophysics Data System (ADS)

Furlong, K. P.; Herman, M. W.

2017-12-01

Following the 2016 Mw 7.8 Kaikoura earthquake, the nature of the coseismic rupture was unclear. Seismological and tsunami evidence pointed to significant involvement of the subduction megathrust, while geodetic and field observations pointed to a shallow set of intra-crustal faults as the main participants during the earthquake. It now appears that the Kaikoura earthquake produced synchronous faulting on the plate boundary subduction interface - the megathrust - and on a suite of crustal faults above the rupture zone in the overlying plate. This Kaikoura-style earthquake, involving synchronous ruptures on multiple components of the plate boundary, may be an important mode of plate boundary deformation affecting seismic hazard along subduction zones. Here we propose a model to explain how these upper-plate faults are loaded during the periods between megathrust earthquakes and subsequently can rupture synchronously with the megathrust. Between megathrust earthquakes, horizontal compression, driven by plate convergence, locks the upper-plate faults, particularly those at higher angles to the convergence direction and the oblique plate motion of the subducting Pacific plate deforms the upper-plate in bulk shear. During the time interval of megathrust rupture, two things happen which directly affect the stress conditions acting on these upper-plate faults: (1) slip on the megathrust and the associated `rebound' of the upper plate reduces the compressive or normal stress acting on the upper plate faults, and (2) the base of the upper plate faults (and the upper plate itself) is decoupled from the slab in the region above rupture area. The reduction in normal stress acting on these faults increases their Coulomb Stress state to strongly favor strike-slip fault slip, and the basal decoupling of the upper plate allows it to undergo nearly complete stress recovery in that region; enabling the occurrence of very large offsets on these faults - offsets that exceed the slip on the plate interface. With these results it is clear that the 2016 Kaikoura NZ earthquake represents a mode of subduction zone rupture that must be considered in other regions.

Slip reactivation model for the 2011 Mw9 Tohoku earthquake: Dynamic rupture, sea floor displacements and tsunami simulations.

NASA Astrophysics Data System (ADS)

Galvez, P.; Dalguer, L. A.; Rahnema, K.; Bader, M.

2014-12-01

The 2011 Mw9 Tohoku earthquake has been recorded with a vast GPS and seismic network given unprecedented chance to seismologists to unveil complex rupture processes in a mega-thrust event. In fact more than one thousand near field strong-motion stations across Japan (K-Net and Kik-Net) revealed complex ground motion patterns attributed to the source effects, allowing to capture detailed information of the rupture process. The seismic stations surrounding the Miyagi regions (MYGH013) show two clear distinct waveforms separated by 40 seconds. This observation is consistent with the kinematic source model obtained from the inversion of strong motion data performed by Lee's et al (2011). In this model two rupture fronts separated by 40 seconds emanate close to the hypocenter and propagate towards the trench. This feature is clearly observed by stacking the slip-rate snapshots on fault points aligned in the EW direction passing through the hypocenter (Gabriel et al, 2012), suggesting slip reactivation during the main event. A repeating slip on large earthquakes may occur due to frictional melting and thermal fluid pressurization effects. Kanamori & Heaton (2002) argued that during faulting of large earthquakes the temperature rises high enough creating melting and further reduction of friction coefficient. We created a 3D dynamic rupture model to reproduce this slip reactivation pattern using SPECFEM3D (Galvez et al, 2014) based on a slip-weakening friction with sudden two sequential stress drops . Our model starts like a M7-8 earthquake breaking dimly the trench, then after 40 seconds a second rupture emerges close to the trench producing additional slip capable to fully break the trench and transforming the earthquake into a megathrust event. The resulting sea floor displacements are in agreement with 1Hz GPS displacements (GEONET). The seismograms agree roughly with seismic records along the coast of Japan.The simulated sea floor displacement reaches 8-10 meters of up-lift close to the trench, which may be the cause of such a devastating tsunami followed by the Tohoku earthquake. To investigate the impact of such a huge up-lift, we ran tsunami simulations with the slip reactivation model using sam(oa)2 (O. Meister et al., 2012), a state-of-the-art Finite-Volume framework to simulate the resulting tsunami waves.

Hovsgol earthquake 5 December 2014, M W = 4.9: seismic and acoustic effects

NASA Astrophysics Data System (ADS)

Dobrynina, Anna A.; Sankov, Vladimir A.; Tcydypova, Larisa R.; German, Victor I.; Chechelnitsky, Vladimir V.; Ulzibat, Munkhuu

2018-03-01

A moderate shallow earthquake occurred on 5 December 2014 ( M W = 4.9) in the north of Lake Hovsgol (northern Mongolia). The infrasonic signal with duration 140 s was recorded for this earthquake by the "Tory" infrasound array (Institute of Solar-Terrestrial Physics of the Siberian Branch of the Russian Academy of Science, Russia). Source parameters of the earthquake (seismic moment, geometrical sizes, displacement amplitudes in the focus) were determined using spectral analysis of direct body P and S waves. The spectral analysis of seismograms and amplitude variations of the surface waves allows to determine the effect of the propagation of the rupture in the earthquake focus, the azimuth of the rupture propagation direction and the velocity of displacement in the earthquake focus. The results of modelling of the surface displacements caused by the Hovsgol earthquake and high effective velocity of propagation of infrasound signal ( 625 m/s) indicate that its occurrence is not caused by the downward movement of the Earth's surface in the epicentral region but by the effect of the secondary source. The position of the secondary source of infrasound signal is defined on the northern slopes of the Khamar-Daban ridge according to the data on the azimuth and time of arrival of acoustic wave at the Tory station. The interaction of surface waves with the regional topography is proposed as the most probable mechanism of formation of the infrasound signal.

Reconstruction of long digital extensor tendon by cranial tibial muscle fascia graft in a dog.

PubMed

Sabiza, Soroush; Khajeh, Ahmad; Naddaf, Hadi

2016-01-01

Tendon rupture in dogs is generally the result of a direct trauma. This report described the use of adjacent muscle autogenic fascial graft for reconstruction of distal rupture of long digital extensor tendon in a dog. A two-year-old male mix breed dog, was presented with a non-weight bearing lameness of the right hind limb and a deep rupture of lateral side of right tarsus. History taking revealed that this rupture appeared without any apparent cause, when walking around the farm, three days before. Radiography was done and no fracture was observed. Hyperextension of right tarsal joint compared to left limb was observed. Under general anesthesia, after dissections of the ruptured area, complete rupture of long digital extensor tendon was revealed. Then, we attempted to locate the edge of the tendon, however, the tendon length was shortened approximately 1 cm. Hence, a strip of 1 cm length from fascia of cranial tibial muscle was harvested to fill the defect. The graft was sutured to the two ends of tendon using locking loop pattern. Subcutaneous layers and the skin were sutured routinely. Ehmer sling bandage was applied to prevent weight bearing on the surgical region. Re-examination and phone contact with the owner eight weeks and six months postoperatively revealed a poor lameness and excellent function of the dog, respectively. It could be concluded that the fascia of adjacent muscles can be used as an autogenic graft for reconstruction of some tendon ruptures.

Reconstruction of long digital extensor tendon by cranial tibial muscle fascia graft in a dog

PubMed Central

Sabiza, Soroush; Khajeh, Ahmad; Naddaf, Hadi

2016-01-01

Tendon rupture in dogs is generally the result of a direct trauma. This report described the use of adjacent muscle autogenic fascial graft for reconstruction of distal rupture of long digital extensor tendon in a dog. A two-year-old male mix breed dog, was presented with a non-weight bearing lameness of the right hind limb and a deep rupture of lateral side of right tarsus. History taking revealed that this rupture appeared without any apparent cause, when walking around the farm, three days before. Radiography was done and no fracture was observed. Hyperextension of right tarsal joint compared to left limb was observed. Under general anesthesia, after dissections of the ruptured area, complete rupture of long digital extensor tendon was revealed. Then, we attempted to locate the edge of the tendon, however, the tendon length was shortened approximately 1 cm. Hence, a strip of 1 cm length from fascia of cranial tibial muscle was harvested to fill the defect. The graft was sutured to the two ends of tendon using locking loop pattern. Subcutaneous layers and the skin were sutured routinely. Ehmer sling bandage was applied to prevent weight bearing on the surgical region. Re-examination and phone contact with the owner eight weeks and six months postoperatively revealed a poor lameness and excellent function of the dog, respectively. It could be concluded that the fascia of adjacent muscles can be used as an autogenic graft for reconstruction of some tendon ruptures. PMID:27872726

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.

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.

Source rupture process of the 12 January 2010 Port-au-Prince (Haiti, Mw7.0) earthquake

NASA Astrophysics Data System (ADS)

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

2010-05-01

The Haiti earthquake occurred on tuesday, January 12, 2010 at 21:53:10 UTC. Its epicenter was at 18.46 degrees North, 72.53 degrees West, about 25 km WSW of Haiti's capital, Port-au-Prince. The earthquake was relatively shallow (H=13 km, U.S. Geological Survey) and thus had greater intensity and destructiveness. The earthquake occurred along the tectonic boundary between Caribbean and North America plate. This plate boundary is dominated by left-lateral strike slip motion and compression with 2 cm/year of slip velocity eastward with respect to the North America plate. The moment magnitude was measured to be 7.0 (U.S. Geological Survey) and 7.1 (Harvard Centroid-Moment-Tensor (CMT). More than 10 aftershocks ranging from 5.0 to 5.9 in magnitude (none of magnitude larger than 6.0) struck the area in hours following the main shock. Most of these aftershocks have occurred to the West of the mainshock in the Mirogoane Lakes region and its distribution suggests that the length of the rupture was around 70 km. The Harvard Centroid Moment Tensor (CMT) mechanism solution indicates lefth-lateral strike slip movement with a fault plane trending toward (strike = 251o ; dip = 70o; rake = 28o). In order to obtain the spatiotemporal slip distribution of a finite rupture model we have used teleseismic body wave and the Kikuchi and Kanamori's method [1]. Rupture velocity was constrained by using the directivity effect determined from a set of waveforms well recorded at regional and teleseismic distances [2]. Finally, we compared a map of aftershocks with the Coulomb stress changes caused by the event in the region [3]. [1]- Kikuchi, M., and Kanamori, H., 1982, Inversion of complex body waves: Bull. Seismol. Soc. Am., v. 72, p. 491-506. [2] 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 (http://www.springerlink.com/content/xp524g2225628773/) [3] -King, G. C. P., Stein, R. S. y Lin, J, 1994, Static stress changes and the triggering of earthquakes. Bull. Seismol. Soc. Am. 84,935-953.

Effect of modifications in mineralized collagen fibril and extra-fibrillar matrix material properties on submicroscale mechanical behavior of cortical bone.

PubMed

Wang, Yaohui; Ural, Ani

2018-06-01

A key length scale of interest in assessing the fracture resistance of bone is the submicroscale which is composed of mineralized collagen fibrils (MCF) and extra-fibrillar matrix (EFM). Although the processes through which the submicroscale constituents of bone contribute to the fracture resistance in bone have been identified, the extent of the modifications in submicroscale mechanical response due to the changes in individual properties of MCFs and EFM has not been determined. As a result, this study aims to quantify the influence of individual MCF and EFM material property modifications on the mechanical behavior (elastic modulus, ultimate strength, and resistance to failure) of bone at the submicroscale using a novel finite element modeling approach that incorporate 3D networks of MCFs with three different orientations as well as explicit representation of EFM. The models were evaluated under tensile loading in transverse (representing MCF separation) and longitudinal (representing MCF rupture) directions. The results showed that the apparent elastic modulus at the submicroscale under both loading directions for all orientations was only affected by the change in the elastic modulus of MCFs. MCF separation and rupture strengths were mainly dependent on the ultimate strength of EFM and MCFs, respectively, with minimal influence of other material properties. The extent of damage during MCF separation increased with increasing ultimate strength of EFM and decreased with increasing fracture energy of EFM with minimal contribution from elastic modulus of MCFs. For MCF rupture, there was an almost one-to-one linear relationship between the percent change in fracture energy of MCFs and the percent change in the apparent submicroscale fracture energy. The ultimate strength and elastic modulus of MCFs had moderate to limited influence on the MCF rupture fracture energy. The results of this study quantified the extent of changes that may be seen in the energy dissipation processes during MCF rupture and separation relative to the changes in the individual constituents of the tissue. This new knowledge significantly contributes to improving the understanding of how the material property alterations at the submicroscale that can occur due to diseases, age-related changes, and treatments affect the fracture processes at larger length scales. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of gravitation stress and hypokinesia on blood vessels of the testicle

NASA Technical Reports Server (NTRS)

Palazhchenko, E. F.

1979-01-01

Rabbits were exposed to single maximum endurable stresses of cranio-caudal direction, hypokinesia for periods of one to eight weeks, and hypokinesia followed by gravitation stresses. The stresses caused dilatation of vessels, greater sinuosity, and occasional ruptures of the walls and extravasation. The greater part of the capillaries were dilated; the greatest part constricted. In hypokinesia there was an increasing atrophy of the testes. Significant results are reported.

Long-wave-instability-induced pattern formation in an evaporating sessile or pendent liquid layer

NASA Astrophysics Data System (ADS)

Wei, Tao; Duan, Fei

2018-03-01

We investigate the nonlinear dynamics and stability of an evaporating liquid layer subject to vapor recoil, capillarity, thermocapillarity, ambient cooling, viscosity, and negative or positive gravity combined with buoyancy effects in the lubrication approximation. Using linear theory, we identify the mechanisms of finite-time rupture, independent of thermocapillarity and direction of gravity, and predict the effective growth rate of an interfacial perturbation which reveals competition among the mechanisms. A stability diagram is predicted for the onset of long-wave (LW) evaporative convection. In the two-dimensional simulation, we observe well-defined capillary ridges on both sides of the valley under positive gravity and main and secondary droplets under negative gravity, while a ridge can be trapped in a large-scale drained region in both cases. Neglecting the other non-Boussinesq effects, buoyancy does not have a significant influence on interfacial evolution and rupture time but makes contributions to the evaporation-driven convection and heat transfer. The average Nusselt number is found to increase with a stronger buoyancy effect. The flow field and interface profile jointly manifest the LW Marangoni-Rayleigh-Bénard convection under positive gravity and the LW Marangoni convection under negative gravity. In the three-dimensional simulation of moderate evaporation with a random perturbation, the rupture patterns are characterized by irregular ridge networks with distinct height scales for positive and negative gravity. A variety of interfacial and internal dynamics are displayed, depending on evaporation conditions, gravity, Marangoni effect, and ambient cooling. Reasonable agreement is found between the present results and the reported experiments and simulations. The concept of dissipative compacton also sheds light on the properties of interfacial fractalization.

Future WGCEP Models and the Need for Earthquake Simulators

NASA Astrophysics Data System (ADS)

Field, E. H.

2008-12-01

The 2008 Working Group on California Earthquake Probabilities (WGCEP) recently released the Uniform California Earthquake Rupture Forecast version 2 (UCERF 2), developed jointly by the USGS, CGS, and SCEC with significant support from the California Earthquake Authority. Although this model embodies several significant improvements over previous WGCEPs, the following are some of the significant shortcomings that we hope to resolve in a future UCERF3: 1) assumptions of fault segmentation and the lack of fault-to-fault ruptures; 2) the lack of an internally consistent methodology for computing time-dependent, elastic-rebound-motivated renewal probabilities; 3) the lack of earthquake clustering/triggering effects; and 4) unwarranted model complexity. It is believed by some that physics-based earthquake simulators will be key to resolving these issues, either as exploratory tools to help guide the present statistical approaches, or as a means to forecast earthquakes directly (although significant challenges remain with respect to the latter).

Need for lung resection in patients with intact or ruptured hydatid cysts.

PubMed

Vasquez, J C; Montesinos, E; Peralta, J; Rojas, L; DeLaRosa, J; Leon, J J

2009-08-01

Lung hydatid cyst caused by Echinococcus granulosus is endemic in many areas of the world. We aimed to compare the outcome of surgical treatment in intact and ruptured (infected or noninfected) cysts. We reviewed the medical records of 115 patients with lung hydatid disease who were surgically treated between 2001 and 2005 in a tertiary hospital in Lima, Peru. Patients were divided into 3 groups based on cyst characteristics: intact cysts (n = 41), ruptured noninfected cysts (n = 47) and ruptured infected cysts (n = 27). If a patient had more than one type of cyst, the most severe form of disease was recorded. Data related to symptoms, morbidity and mortality were recorded and compared. We also calculated direct patient costs. Mean age of patients was 23.6 +/- 15.1 years old. Ruptured cysts were present in 64 % of patients and giant cysts (> 10 cm diameter) were present in 26 % of patients. Hemoptysis was present in 47.0 % of patients and was more frequent in patients with ruptured infected cysts. Lung resection was performed in 58 % of patients. The most common postoperative complication was infection of the operative wound (6.08 %). Perioperative mortality was zero. Patients with ruptured cysts had a longer hospitalization time and higher total cost (12.28 +/- 0.92 days, US$ 890.34 +/- 303.35) than patients with intact cysts (10.17 +/- 0.79 days, US$ 724.81 +/- 14.38). Surgical treatment of lung hydatid disease is safe, with a good outcome and a low mortality rate. The lung resection rate was higher than most published series and reflects the relatively high proportion of patients with giant and ruptured infected cysts.

A Method for Direct-Measurement of the Energy of Rupture of Impact Specimens

DTIC Science & Technology

1953-01-01

CONTENTS SECTION A - Poreword SFCTION B » ObjectiTes of the Current Investigation SECTION C - Basic Elements of an Impact Testing System ...SECTION D - Discussion lo Linear System 2 c Rotary System 3o Methods for Ifeasui ing the Energy of Rupture SECTION E « The Energy Measuring System ...has followed and to siironarize our techni<»l findings, Co BASIC ELEKEMTS OF AN IMPACT TESTING SYSTEM For the analytical purposes of this

Dissecting the structural determinants for the difference in mechanical stability of silk and amyloid beta-sheet stacks.

PubMed

Xiao, Senbo; Xiao, Shijun; Gräter, Frauke

2013-06-14

Stacking of β-sheets results in a protein super secondary structure with remarkable mechanical properties. β-Stacks are the determinants of a silk fiber's resilience and are also the building blocks of amyloid fibrils. While both silk and amyloid-type crystals are known to feature a high resistance against rupture, their structural and mechanical similarities and particularities are yet to be fully understood. Here, we systematically compare the rupture force and stiffness of amyloid and spider silk poly-alanine β-stacks of comparable sizes using Molecular Dynamics simulations. We identify the direction of force application as the primary determinant of the rupture strength; β-sheets in silk are orientated along the fiber axis, i.e. the pulling direction, and consequently require high forces in the several nanoNewton range for shearing β-strands apart, while β-sheets in amyloid are oriented vertically to the fiber, allowing a zipper-like rupture at sub-nanoNewton forces. A secondary factor rendering amyloid β-stacks softer and weaker than their spider silk counterparts is the sub-optimal side-chain packing between β-sheets due to the sequence variations of amyloid-forming proteins as opposed to the perfectly packed poly-alanine β-sheets of silk. Taken together, amyloid fibers can reach the stiffness of silk fibers in spite of their softer and weaker β-sheet arrangement as they are missing a softening amorphous matrix.

A novel approach to symptomatic lumbar facet joint synovial cyst injection and rupture using iGuide navigational software: A case report and review.

PubMed

Wang, David J; Lownie, Stephen P; Pelz, David; Pandey, Sachin

2016-10-01

Spinal synovial cysts are benign protrusions of facet joint capsules caused by degenerative spondylosis, most frequently involving the L4-5 level, and commonly lead to symptoms of back pain, radiculopathy and neurogenic claudication. Although percutaneous treatment via facet joint steroid injection with cyst rupture can provide significant symptom relief, cyst rupture is not always achievable via an indirect trans-facet approach due to limited access from severe degenerative changes. In this case, we describe a successful approach to direct cyst access using a laser-guided navigational software in a patient with severe facet joint osteophytosis. We provide a brief review of literature. © The Author(s) 2016.

Ground motion modeling of the 1906 San Francisco earthquake II: Ground motion estimates for the 1906 earthquake and scenario events

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

Aagaard, B; Brocher, T; Dreger, D

2007-02-09

We estimate the ground motions produced by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sitesmore » throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.« less

Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events

USGS Publications Warehouse

Aagaard, Brad T.; Brocher, T.M.; Dolenc, D.; Dreger, D.; Graves, R.W.; Harmsen, S.; Hartzell, S.; Larsen, S.; McCandless, K.; Nilsson, S.; Petersson, N.A.; Rodgers, A.; Sjogreen, B.; Zoback, M.L.

2008-01-01

We estimate the ground motions produce by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sites throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.

Seismogenic width controls aspect ratios of earthquake ruptures

NASA Astrophysics Data System (ADS)

Weng, Huihui; Yang, Hongfeng

2017-03-01

We investigate the effect of seismogenic width on aspect ratios of earthquake ruptures by using numerical simulations of strike-slip faulting and an energy balance criterion near rupture tips. If the seismogenic width is smaller than a critical value, then ruptures cannot break the entire fault, regardless of the size of the nucleation zone. The seismic moments of these self-arresting ruptures increase with the nucleation size, forming nucleation-related events. The aspect ratios increase with the seismogenic width but are smaller than 8. In contrast, ruptures become breakaway and tend to have high aspect ratios (>8) if the seismogenic width is sufficiently large. But the critical nucleation size is larger than the theoretical estimate for an unbounded fault. The eventual seismic moments of breakaway ruptures do not depend on the nucleation size. Our results suggest that estimating final earthquake magnitude from the nucleation phase may only be plausible on faults with small seismogenic width.

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.

Free recall memory performance after aneurysmal subarachnoid hemorrhage.

PubMed

Sheldon, Signy; Macdonald, R Loch; Schweizer, Tom A

2012-03-01

Memory deficits for survivors of aneurysmal subarachnoid hemorrhage (SAH) are common, however, the nature of these deficits is not well understood. In this study, 24 patients with SAH and matched control participants were asked to study six lists containing words from four different categories. For half the lists, the categories were presented together (organized lists). For the remaining lists, the related words were presented randomly to maximize the use of executive processes such as strategy and organization (unorganized lists). Across adjoining lists, there was overlap in the types of categories given, done to promote intrusions. Compared to control participants, SAH patients recalled a similar number of words for the organized lists, but significantly fewer words for the unorganized lists. SAH patients also reported more intrusions than their matched counterparts. Separating patients into anterior communicating artery ruptures (ACoA) and ruptures in other regions, there was a recall deficit only for the unorganized list for those with ACoA ruptures and deficits across both list types for other rupture locations. These results suggest that memory impairment following SAH is likely driven by impairment in the executive components of memory, particularly for those with ACoA ruptures. Such findings may help direct future cognitive-therapeutic programs.

Near-field radiated wave field may help to understand the style of the supershear transition of dynamic ruptures

NASA Astrophysics Data System (ADS)

Bizzarri, Andrea; Liu, Chao

2016-12-01

Supershear earthquakes are known to leave special signatures in the signals on the fault (fault slip velocity, dynamic traction evolution, energy flux, etc.) and in the ground motions. Moreover, two different styles of supershear transition have been identified; in the direct transition (DT) mechanism the rupture speed continuously increases from the sub-Rayleigh to the terminal speed of P waves, while in the mother-daughter (MD) mechanism a forbidden zone of rupture speed exists and a secondary pseudo-rupture is generated ahead of the primary rupture front. Here we found that the off-fault signals (wavefields) generated by these two mechanisms are rather different, in that the MD case contains an enhanced trailing Rayleigh field, which has very low amplitudes (or it is even practically absent) in the DT case, and possess higher frequency content. Therefore, we show that it is possible to distinguish the style of the supershear transition from the records of real earthquakes. In particular, basing on the results of our numerical simulations, we can conclude that the Denali, Alaska, earthquake was basically controlled by a classical MD mechanism.

Rupture process of the September 12, 2007 Southern Sumatra earthquake from tsunami waveform inversion

NASA Astrophysics Data System (ADS)

Lorito, S.; Romano, F.; Piatanesi, A.

2007-12-01

The aim of this work is to infer the slip distribution and mean rupture velocity along the rupture zone of the 12 September 2007 Southern Sumatra, Indonesia from available tide-gauge records of the tsunami. We select waveforms from 12 stations, distributed along the west coast of Sumatra and in the whole Indian Ocean (11 GLOSS stations and 1 DART buoy). We assume the fault plane and the slip direction to be consistent with both the geometry of the subducting plate and the early focal mechanism solutions. Then we subdivide the fault plane into several subfaults (both along strike and down dip) and compute the corresponding Green's functions by numerical solution of the shallow water equations through a finite difference method. The slip distribution and rupture velocity are determined simultaneously by means of a simulated annealing technique. We compare the recorded and synthetic waveforms in the time domain, using a cost function that is a trade-off between the L1 and L2 norms. Preliminary synthetic checkerboard tests, using the station coverage and the sampling interval of the available data, indicate that the main features of the rupture process may be robustly inverted.

Rupture of a jejunal artery aneurysm.

PubMed

Asano, Migiwa; Nushida, Hideyuki; Nagasaki, Yasushi; Tatsuno, Yoshitsugu; Ueno, Yasuhiro

2008-09-01

Aneurysm of the superior mesenteric artery or its branches is rare. We herein present a case of a ruptured aneurysm of the jejunal artery, a branch of the superior mesenteric artery, and we also review 19 cases of jejunal artery aneurysm reported in the English literature. A 66-year-old male who had received a fist blow to the face presented in the emergency ward of his local hospital. His physical examination was unremarkable and he went back home after treatment of his facial wound. Two hours later he again visited the hospital, this time for severe abdominal pain, and he was hospitalized for suspicion of an intraperitoneal hemorrhage. Selective arteriography of the superior mesenteric artery revealed a ruptured aneurysm in the first branch of the jejunal artery. An emergency laparotomy was performed, but the patient died 29h after the injury. Because there was no evidence of any trauma to the abdomen, we concluded that the cause of death was exsanguination due to a ruptured aneurysm, and was not directly related to the earlier trauma. This case is considered to be of medico-legal interest regarding whether the rupture resulted from a natural disease or was due to an assault.

Geodetic insights on the post-seismic transients from the Andaman Nicobar region: 2005-2013

NASA Astrophysics Data System (ADS)

Earnest, A.; Vijayan, M.; Jade, S.; Krishnan, R.; Sringeri, S. T.

2013-12-01

The 2004 Mw 9.2 Sumatra-Andaman mega-thrust rupture broke the whole 1300 km long fore-arc sliver boundary of the Indo- Burmese collision. Earlier events of 1679 (M~7.5), 1941 (M 7.7), 1881 (M~7.9) and 2002 (Mw 7.3) generated spatially restricted ruptures along this margin. GPS based geodetic measurements of post-seismic deformation following the 2004 M9.2 Sumatra-Andaman earthquake gives insights on the spatio-temporal evolution of transient tectonic deformation happening at the Suda-Andaman margin. This work encompasses the near-field geodetic data collected from the Andaman-Nicobar Islands and far-field CGPS site data available from SUGAR, UNAVCO and IGS from 2005-2013. Precise geodetic data analysis shows that the GPS benchmarks in the Andaman-Nicobar region moved immediately after 2004 event towards the sea-ward trench in the SW direction, following very much the co-seismic offset directions. This can be possibly because of the continued predominant after-slip occurrence around the 2004 rupture zone due to the velocity-strengthening behavior at the downdip segments of the rupture zone. Lately a progressive reversal of motion direction away from the oceanic trench (and the co-seismic offset direction) of the coastal and inland GPS sites of Andaman-Nicobar Islands are observed. The site displacement transients shows a rotation of the displacement vector moving from south-west to north. Spatio-temporal analysis of the earthquakes show dense shallow seismicity in the back-arc region, normal and thrust faulting activity towards the trench. The hypo-central distribution highlights the shallow subduction at the northern segment, which becomes steeper and deeper to the south. The stress distribution, inferred from the P and T-axes of earthquake faulting mechanisms, represents the compressional fore-arc and extensional back-arc stress regimes. Our analysis results will be discussed in detail by integrating the kinematics and seismo-tectonic evolution of this subducting margin for the post-seismic period from 2005 - 2013.

Laboratory investigations of earthquake dynamics

NASA Astrophysics Data System (ADS)

Xia, Kaiwen

In this thesis this will be attempted through controlled laboratory experiments that are designed to mimic natural earthquake scenarios. The earthquake dynamic rupturing process itself is a complicated phenomenon, involving dynamic friction, wave propagation, and heat production. Because controlled experiments can produce results without assumptions needed in theoretical and numerical analysis, the experimental method is thus advantageous over theoretical and numerical methods. Our laboratory fault is composed of carefully cut photoelastic polymer plates (Homahte-100, Polycarbonate) held together by uniaxial compression. As a unique unit of the experimental design, a controlled exploding wire technique provides the triggering mechanism of laboratory earthquakes. Three important components of real earthquakes (i.e., pre-existing fault, tectonic loading, and triggering mechanism) correspond to and are simulated by frictional contact, uniaxial compression, and the exploding wire technique. Dynamic rupturing processes are visualized using the photoelastic method and are recorded via a high-speed camera. Our experimental methodology, which is full-field, in situ, and non-intrusive, has better control and diagnostic capacity compared to other existing experimental methods. Using this experimental approach, we have investigated several problems: dynamics of earthquake faulting occurring along homogeneous faults separating identical materials, earthquake faulting along inhomogeneous faults separating materials with different wave speeds, and earthquake faulting along faults with a finite low wave speed fault core. We have observed supershear ruptures, subRayleigh to supershear rupture transition, crack-like to pulse-like rupture transition, self-healing (Heaton) pulse, and rupture directionality.

Creep rupture analysis of a beam resting on high temperature foundation

NASA Technical Reports Server (NTRS)

Gu, Randy J.; Cozzarelli, Francis A.

1988-01-01

A simplified uniaxial strain controlled creep damage law is deduced with the use of experimental observation from a more complex strain dependent law. This creep damage law correlates the creep damage, which is interpreted as the density variation in the material, directly with the accumulated creep strain. Based on the deduced uniaxial strain controlled creep damage law, a continuum mechanical creep rupture analysis is carried out for a beam resting on a high temperature elastic (Winkler) foundation. The analysis includes the determination of the nondimensional time for initial rupture, the propagation of the rupture front with the associated thinning of the beam, and the influence of creep damage on the deflection of the beam. Creep damage starts accumulating in the beam as soon as the load is applied, and a creep rupture front develops at and propagates from the point at which the creep damage first reaches its critical value. By introducing a series of fundamental assumptions within the framework of technical Euler-Bernoulli type beam theory, a governing set of integro-differential equations is derived in terms of the nondimensional bending moment and the deflection. These governing equations are subjected to a set of interface conditions at the propagating rupture front. A numerical technique is developed to solve the governing equations together with the interface equations, and the computed results are presented and discussed in detail.

[Secondary tendon reconstruction on the thumb].

PubMed

Bickert, B; Kremer, T; Kneser, U

2016-12-01

Closed tendon ruptures of the thumb that require secondary reconstruction can affect the extensor pollicis longus (EPL), extensor pollicis brevis (EPB) and flexor pollicis longus (FPL) tendons. Treatment of rupture of the EPB tendon consists of refixation to the bone and temporary transfixation of the joint. In the case of preexisting or posttraumatic arthrosis, definitive arthrodesis of the thumb is the best procedure. Closed ruptures of the EPL and FPL tendons at the wrist joint cannot be treated by direct tendon suture. Rupture of the EPL tendon occurs after distal radius fractures either due to protruding screws or following conservative treatment especially in undisplaced fractures. Transfer of the extensor indicis tendon to the distal EPL stump is a good option and free interposition of the palmaris longus tendon is a possible alternative. The tension should be adjusted to slight overcorrection, which can be checked intraoperatively by performing the tenodesis test. Closed FPL ruptures at the wrist typically occur 3-6 months after osteosynthesis of distal radius fractures with palmar plates and are mostly characterized by crepitation and pain lasting for several weeks. They can be prevented by premature plate removal, synovectomy and carpal tunnel release. For treatment of a ruptured FPL tendon in adult patients the options for tendon reconstruction should be weighed up against the less complicated tenodesis or arthrodesis of the thumb interphalangeal joint.

2017 Valparaíso earthquake sequence and the megathrust patchwork of central Chile

NASA Astrophysics Data System (ADS)

Nealy, Jennifer L.; Herman, Matthew W.; Moore, Ginevra L.; Hayes, Gavin P.; Benz, Harley M.; Bergman, Eric A.; Barrientos, Sergio E.

2017-09-01

In April 2017, a sequence of earthquakes offshore Valparaíso, Chile, raised concerns of a potential megathrust earthquake in the near future. The largest event in the 2017 sequence was a M6.9 on 24 April, seemingly colocated with the last great-sized earthquake in the region—a M8.0 in March 1985. The history of large earthquakes in this region shows significant variation in rupture size and extent, typically highlighted by a juxtaposition of large ruptures interspersed with smaller magnitude sequences. We show that the 2017 sequence ruptured an area between the two main slip patches during the 1985 earthquake, rerupturing a patch that had previously slipped during the October 1973 M6.5 earthquake sequence. A significant gap in historic ruptures exists directly to the south of the 2017 sequence, with large enough moment deficit to host a great-sized earthquake in the near future, if it is locked.

2017 Valparaíso earthquake sequence and the megathrust patchwork of central Chile

USGS Publications Warehouse

Nealy, Jennifer; Herman, Matthew W.; Moore, Ginevra; Hayes, Gavin; Benz, Harley M.; Bergman, Eric A.; Barrientos, Sergio E

2017-01-01

In April 2017, a sequence of earthquakes offshore Valparaíso, Chile, raised concerns of a potential megathrust earthquake in the near future. The largest event in the 2017 sequence was a M6.9 on 24 April, seemingly colocated with the last great-sized earthquake in the region—a M8.0 in March 1985. The history of large earthquakes in this region shows significant variation in rupture size and extent, typically highlighted by a juxtaposition of large ruptures interspersed with smaller magnitude sequences. We show that the 2017 sequence ruptured an area between the two main slip patches during the 1985 earthquake, rerupturing a patch that had previously slipped during the October 1973 M6.5 earthquake sequence. A significant gap in historic ruptures exists directly to the south of the 2017 sequence, with large enough moment deficit to host a great-sized earthquake in the near future, if it is locked.

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.

Seismic shaking in the North China Basin expected from ruptures of a possible seismic gap

NASA Astrophysics Data System (ADS)

Duan, Benchun; Liu, Dunyu; Yin, An

2017-05-01

A 160 km long seismic gap, which has not been ruptured over 8000 years, was identified recently in North China. In this study, we use a dynamic source model and a newly available high-resolution 3-D velocity structure to simulate long-period ground motion (up to 0.5 Hz) from possibly worst case rupture scenarios of the seismic gap. We find that the characteristics of the earthquake source and the local geologic structure play a critical role in controlling the amplitude and distribution of the simulated strong ground shaking. Rupture directivity and slip asperities can result in large-amplitude (i.e., >1 m/s) ground shaking near the fault, whereas long-duration shaking may occur within sedimentary basins. In particular, a deep and closed Quaternary basin between Beijing and Tianjin can lead to ground shaking of several tens of cm/s for more than 1 min. These results may provide a sound basis for seismic mitigation in one of the most populated regions in the world.

Long-term results of middle cerebral artery aneurysm clipping in the Barrow Ruptured Aneurysm Trial.

PubMed

Mooney, Michael A; Simon, Elias D; Brigeman, Scott; Nakaji, Peter; Zabramski, Joseph M; Lawton, Michael T; Spetzler, Robert F

2018-04-27

OBJECTIVE A direct comparison of endovascular versus microsurgical treatment of ruptured middle cerebral artery (MCA) aneurysms in randomized trials is lacking. As endovascular treatment strategies continue to evolve, the number of reports of endovascular treatment of these lesions is increasing. Herein, the authors report a detailed post hoc analysis of ruptured MCA aneurysms treated by microsurgical clipping from the Barrow Ruptured Aneurysm Trial (BRAT). METHODS The cases of patients enrolled in the BRAT who underwent microsurgical clipping for a ruptured MCA aneurysm were reviewed. Characteristics of patients and their clinical outcomes and long-term angiographic results were analyzed. RESULTS Fifty patients underwent microsurgical clipping of a ruptured MCA aneurysm in the BRAT, including 21 who crossed over from the endovascular treatment arm. Four patients with nonsaccular (e.g., dissecting, fusiform, or blister) aneurysms were excluded, leaving 46 patients for analysis. Most (n = 32; 70%) patients presented with a Hunt and Hess grade II or III subarachnoid hemorrhage, with a high prevalence of intraparenchymal blood (n = 23; 50%), intraventricular blood (n = 21; 46%), or both. At the last follow-up (up to 6 years after treatment), clinical outcomes were good (modified Rankin Scale score 0-2) in 70% (n = 19) of 27 Hunt and Hess grades I-III patients and in 36% (n = 4) of 11 Hunt and Hess grade IV or V patients. There were no instances of rebleeding after the surgical clipping of aneurysms in this series at the time of last clinical follow-up. CONCLUSIONS Microsurgical clipping of ruptured MCA aneurysms has several advantages over endovascular treatment, including durability over time. The authors report detailed outcome data of patients with ruptured MCA aneurysms who underwent microsurgical clipping as part of a prospective, randomized trial. These results should be used for comparison with future endovascular and surgical series to ensure that the best results are being achieved for patients with ruptured MCA aneurysms.

Poly Implant Prothèse (PIP) incidence of rupture: a retrospective MR analysis in 64 patients

PubMed Central

Scotto di Santolo, Mariella; Cusati, Bianca; Ragozzino, Alfonso; Dell’Aprovitola, Nicoletta; Acquaviva, Alessandra; Altiero, Michele; Accurso, Antonello; Riccardi, Albina

2014-01-01

Aim of the study The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) features of Poly Implant Prothèse (PIP) hydrogel implants in a group of 64 patients and to assess the incidence of rupture, compared to other clinical trials. Material and methods In this double-center study, we retrospectively reviewed the data sets of 64 consecutive patients (mean age, 43±9 years, age range, 27-65 years), who underwent breast MRI examinations, between January 2008 and October 2013, with suspected implant rupture on the basis of clinical assessment or after conventional imaging examination (either mammography or ultrasound). All patients had undergone breast operation with bilateral textured cohesive gel PIP implant insertion for aesthetic reasons. The mean time after operation was 8 years (range, 6-14 years). No patients reported history of direct trauma to their implants. Results At the time of clinical examination, 41 patients were asymptomatic, 16 complained of breast tenderness and 7 had clinical evidence of rupture. Normal findings were observed in 15 patients. In 26 patients there were signs of mild collapse, with associated not significant peri-capsular fluid collections and no evidence of implant rupture; in 23 patients there was suggestion of implant rupture, according to breast MRI leading to an indication for surgery. In particular, 14 patients showed intra-capsular rupture, with associated evidence of the linguine sign in all cases; the keyhole sign and the droplet signs were observed in 6 cases. In 9 patients there was evidence of extra-capsular rupture, with presence of axillary collections (siliconomas) in 7 cases and peri-prosthetic and mediastinal cavity siliconomas, in 5 cases. Conclusions The results of this double center retrospective study, confirm the higher incidence (36%) of prosthesis rupture observed with the PIP implants, compared to other breast implants. PMID:25525578

Rupture directivity and local site effects: the M7.3 Honduras earthquake of May 23, 2009

NASA Astrophysics Data System (ADS)

Shulman, D.; Mooney, W. D.

2009-12-01

On May 28, 2009, at 2:24 AM local time, a M 7.3 earthquake struck off the coast of Honduras on the Motagua-Swan Fault System (MSFS), part of the boundary between the North America and Caribbean plates. This plate boundary has an average slip rate of 20 mm/year. This left-lateral earthquake had an average slip of 1.5 m on a 100-km-long near-vertical fault plane (Hayes and Ji, 2009). The hypocenter depth is estimated at 10 km. The main shock caused 130 structures, including homes and office buildings, to collapse or suffer significant damage in northern Honduras. Seven deaths were reported. Due to a lack of recordings in the area, the available documentation of the local effects of this earthquake are the USGS "Did you feel it?" responses and the data collected during our field seismic intensity investigation. We conducted a field investigation in Honduras between May 30 and June 6, 2009, focused on areas with local reports of damage, including the cities of La Ceiba, El Progresso, San Pedro Sula, Puerto Cortes in northern Honduras and the island of Roatan in the Caribbean Sea. The damage ascertained at these five sites shows that the severity of damage did not decrease with distance from the epicenter as predicted by standard attenuation relations. Instead, a concentration of damage was observed in El Progresso, approximately 75 km directly south from the SW end of the rupture and 160 km from the epicenter. The island of Roatan, just 30 km from the epicenter, was graded as VI on the Modified Mercalli Intensity scale while, El Progresso was graded as VIII (one unit higher than “Did you feel it?”). These intensity anomalies can be explained by two factors: (1) SW-directed rupture propagation and proximity to a localized 3.0m slip pulse (asperity) that occurred near the SW end of the fault (Hayes and Ji, 2009) that focused energy toward the city of El Progress on the mainland and; (2) local site effects, particularly the Precambrian schists and gneisses on the island of Roatan, in contrast to the soft river deposits (sand, organics, and clay) beneath the city of El Progresso. This study demonstrates the impact of seismic directivity, a fault asperity, and local site conditions on the observed damage patterns from the May 28, 2009 M 7.3 earthquake.

Suppression of slip and rupture velocity increased by thermal pressurization: Effect of dilatancy

NASA Astrophysics Data System (ADS)

Urata, Yumi; Kuge, Keiko; Kase, Yuko

2013-11-01

investigated the effect of dilatancy on dynamic rupture propagation on a fault where thermal pressurization (TP) is in effect, taking into account permeability varying with porosity; the study is based on three-dimensional (3-D) numerical simulations of spontaneous ruptures obeying a slip-weakening friction law and Coulomb failure criterion. The effects of dilatancy on dynamic ruptures interacting with TP have been often investigated in one- or two-dimensional numerical simulations. The sole 3-D numerical simulation gave attention only to the behavior at a single point on a fault. Moreover, with the sole exception based on a single-degree-freedom spring-slider model, the previous simulations including dilatancy and TP have not considered changes in hydraulic diffusivity. However, the hydraulic diffusivity, which strongly affects TP, can vary as a power of porosity. In this study, we apply a power law relationship between permeability and porosity. We consider both reversible and irreversible changes in porosity, assuming that the irreversible change is proportional to the slip rate and dilatancy coefficient ɛ. Our numerical simulations suggest that the effects of dilatancy can suppress slip and rupture velocity increased by TP. The results reveal that the amount of slip on the fault decreases with increasing ɛ or exponent of the power law, and the rupture velocity is predominantly suppressed by ɛ. This was observed regardless of whether the applied stresses were high or low. The deficit of the final slip in relation to ɛ can be smaller as the fault size is larger.

Lipid-Lowering Agents and High HDL (High-Density Lipoprotein) Are Inversely Associated With Intracranial Aneurysm Rupture.

PubMed

Can, Anil; Castro, Victor M; Dligach, Dmitriy; Finan, Sean; Yu, Sheng; Gainer, Vivian; Shadick, Nancy A; Savova, Guergana; Murphy, Shawn; Cai, Tianxi; Weiss, Scott T; Du, Rose

2018-05-01

Growing evidence from experimental animal models and clinical studies suggests the protective effect of statin use against rupture of intracranial aneurysms; however, results from large studies detailing the relationship between intracranial aneurysm rupture and total cholesterol, HDL (high-density lipoprotein), LDL (low-density lipoprotein), and lipid-lowering agent use are lacking. The medical records of 4701 patients with 6411 intracranial aneurysms diagnosed at the Massachusetts General Hospital and the Brigham and Women's Hospital between 1990 and 2016 were reviewed and analyzed. Patients were separated into ruptured and nonruptured groups. Univariable and multivariable logistic regression analyses were performed to determine the effects of lipids (total cholesterol, LDL, and HDL) and lipid-lowering medications on intracranial aneurysm rupture risk. Propensity score weighting was used to account for differences in baseline characteristics of the cohorts. Lipid-lowering agent use was significantly inversely associated with rupture status (odds ratio, 0.58; 95% confidence interval, 0.47-0.71). In a subgroup analysis of complete cases that includes both lipid-lowering agent use and lipid values, higher HDL levels (odds ratio, 0.95; 95% confidence interval, 0.93-0.98) and lipid-lowering agent use (odds ratio, 0.41; 95% confidence interval, 0.23-0.73) were both significantly and inversely associated with rupture status, whereas total cholesterol and LDL levels were not significant. A monotonic exposure-response curve between HDL levels and risk of aneurysmal rupture was obtained. Higher HDL values and the use of lipid-lowering agents are significantly inversely associated with ruptured intracranial aneurysms. © 2018 American Heart Association, Inc.

Modeling the effects of source and path heterogeneity on ground motions of great earthquakes on the Cascadia Subduction Zone Using 3D simulations

USGS Publications Warehouse

Delorey, Andrew; Frankel, Arthur; Liu, Pengcheng; Stephenson, William J.

2014-01-01

We ran finite‐difference earthquake simulations for great subduction zone earthquakes in Cascadia to model the effects of source and path heterogeneity for the purpose of improving strong‐motion predictions. We developed a rupture model for large subduction zone earthquakes based on a k−2 slip spectrum and scale‐dependent rise times by representing the slip distribution as the sum of normal modes of a vibrating membrane.Finite source and path effects were important in determining the distribution of strong motions through the locations of the hypocenter, subevents, and crustal structures like sedimentary basins. Some regions in Cascadia appear to be at greater risk than others during an event due to the geometry of the Cascadia fault zone relative to the coast and populated regions. The southern Oregon coast appears to have increased risk because it is closer to the locked zone of the Cascadia fault than other coastal areas and is also in the path of directivity amplification from any rupture propagating north to south in that part of the subduction zone, and the basins in the Puget Sound area are efficiently amplified by both north and south propagating ruptures off the coast of western Washington. We find that the median spectral accelerations at 5 s period from the simulations are similar to that of the Zhao et al. (2006) ground‐motion prediction equation, although our simulations predict higher amplitudes near the region of greatest slip and in the sedimentary basins, such as the Seattle basin.

Surgical repair of a rupture of the pectoralis major muscle

PubMed Central

Pochini, Alberto De Castro; Andreoli, Carlos Vicente; Ejnisman, Benno; Maffulli, Nicola

2015-01-01

Muscle rupture is rarely treated surgically. Few reports of good outcomes after muscular suture have been published. Usually, muscular lesions or partial ruptures heal with few side effects or result in total recovery. We report a case of an athlete who was treated surgically to repair a total muscular rupture in the pectoralis major muscle. After 6 months, the athlete returned to competitive practice. After a 2-year follow-up, the athlete still competes in skateboard championships. PMID:25716033

A Deterministic Methodology for Discriminating between Earthquakes and Underground Nuclear Explosions

DTIC Science & Technology

1976-07-01

rupture (right) to represent a bilat- eral rupture is described in the text Page 48 50 51 56 60 3.11 Far-field radiation patterns for the bi ...particularly effective for detecting, isolating and timing the various seismic phases ^g’ p*’ pn’ Sg’ s*’ Sn , etc.) that are recorded on event seismograms in...of the stress field during rupture. 5. A criterion allowing the rupture to heal . All earthquake models must, implicitly or explicitly, deal with

Studying Near-Trench Characteristics of the 2011 Tohoku-Oki Megathrust Rupture Using Differential Multi-Beam Bathymetry before and after the Earthquake

NASA Astrophysics Data System (ADS)

Sun, T.; Fujiwara, T.; Kodaira, S.; Wang, K.; He, J.

2014-12-01

Large coseismic motion (up to ~ 31 m) of seafloor GPS sites during the 2011 M 9 Tohoku earthquake suggests large rupture at shallow depths of the megathrust. However, compilation of all published rupture models, constrained by the near-field seafloor geodetic observation and also various other datasets, shows large uncertainties in the slip of the most near-trench (within ~ 50 km from the trench) part of the megathrust. Repeated multi-beam bathymetry surveys that cover the trench axis, carried out by Japan Agency for Marine-Earth Science and Technology, for the first time recorded coseismic deformation in a megathrust earthquake at the trench. In previous studies of the differential bathymetry (DB) before and after the earthquake to determine coseismic fault slip, only the rigid-body translation component of the upper plate deformation was considered. In this work, we construct Synthetic Differential Bathymetry (SDB) using an elastic deformation model and make comparisons with the observed DB. We use a 3-D elastic Finite Element model with actual fault geometry of the Japan trench subduction zone and allowing the rupture to breach the trench. The SDB can well predict short-wavelength variations in the observed DB. Our tests using different coseismic slip models show that the internal elastic deformation of the hanging wall plays an important role in generating DB. Comparing the SDB with the observed DB suggests that the largest slip is located within ~ 50 km from the trench. The SDB proves to be the most effective tool to evaluate the performance of different rupture models in predicting near-trench slip. Our SDB work will further explore the updip slip variation. The SDB may help to constrain the slip gradient in the updip direction and may help to determine whether the large shallow slip in the Tohoku earthquake plateaued at the trench or before reaching the trench. Resolving these issues will provide some of the key tests for various competing models that were proposed to explain the large shallow rupture in this event.

The effect of segmented fault zones on earthquake rupture propagation and termination

NASA Astrophysics Data System (ADS)

Huang, Y.

2017-12-01

A fundamental question in earthquake source physics is what can control the nucleation and termination of an earthquake rupture. Besides stress heterogeneities and variations in frictional properties, damaged fault zones (DFZs) that surround major strike-slip faults can contribute significantly to earthquake rupture propagation. Previous earthquake rupture simulations usually characterize DFZs as several-hundred-meter-wide layers with lower seismic velocities than host rocks, and find earthquake ruptures in DFZs can exhibit slip pulses and oscillating rupture speeds that ultimately enhance high-frequency ground motions. However, real DFZs are more complex than the uniform low-velocity structures, and show along-strike variations of damages that may be correlated with historical earthquake ruptures. These segmented structures can either prohibit or assist rupture propagation and significantly affect the final sizes of earthquakes. For example, recent dense array data recorded at the San Jacinto fault zone suggests the existence of three prominent DFZs across the Anza seismic gap and the south section of the Clark branch, while no prominent DFZs were identified near the ends of the Anza seismic gap. To better understand earthquake rupture in segmented fault zones, we will present dynamic rupture simulations that calculate the time-varying rupture process physically by considering the interactions between fault stresses, fault frictional properties, and material heterogeneities. We will show that whether an earthquake rupture can break through the intact rock outside the DFZ depend on the nucleation size of the earthquake and the rupture propagation distance in the DFZ. Moreover, material properties of the DFZ, stress conditions along the fault, and friction properties of the fault also have a critical impact on rupture propagation and termination. We will also present scenarios of San Jacinto earthquake ruptures and show the parameter space that is favorable for rupture propagation through the Anza seismic gap. Our results suggest that a priori knowledge of properties of segmented fault zones is of great importance for predicting sizes of future large earthquakes on major faults.

Observations of the rupture development process from source time functions

NASA Astrophysics Data System (ADS)

Renou, Julien; Vallée, Martin

2017-04-01

The mechanisms governing the seismic rupture expansion and leading to earthquakes of very different magnitudes are still under debate. In the cascade model, the rupture starts from a very small patch, which size is undetectable by seismological investigation. Then rupture grows in a self-similar way, implying that no clues about the earthquake magnitude can be found before rupture starts declining. However dependencies between early phases of the rupture process and final magnitude have also been proposed, which can be explained if an earthquake is more likely to be a big one when its start and early development occur in rupture-prone areas. Here, the analysis of the early phases of the seismic rupture is achieved from an observational point of view using the SCARDEC database, a global catalog containing more than 3000 Source Time Functions (STFs) of earthquakes with magnitude larger than 5.7. This dataset is theoretically very suitable to investigate the initial phase, because STFs directly describe the seismic moment rate released over time, giving access to the rupture growth behavior. As several studies already showed that deep earthquakes tend to have a specific signature of short duration with respect to magnitude (implying a quicker rupture growth than superficial events), only shallow events (depths < 70km) are analyzed here. Our method consists in computing the STFs slope, i.e. the seismic moment acceleration, at several prescribed moment rates. In order to ensure that the chosen moment rates intersect the growth phase of the STF, its value must be high enough to avoid the very beginning of the signal -not well constrained in the deconvolution process-, and low enough to avoid the proximity of the peak moment rate. This approach does not use any rupture time information, which is interesting as (1) the exact hypocentral time can be uncertain and (2) the real rupture expansion can be delayed compared to origin time. If any magnitude-dependent signal exists, the average or median value of the slope should vary with the magnitude of the events, despite the intrinsic variability of the STFs. The preliminary results from the SCARDEC dataset seem to only exhibit a weak dependence of the slope with magnitude, in the magnitude domain where the chosen moment rate value crosses most of the STFs onsets. In addition, our results point out that slope values gradually increase with the moment rate. These findings will be discussed in the frame of the existing models of seismic rupture expansion.

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.

Successful Coil Embolization of a Ruptured Basilar Artery Aneurysm in a Child with Leukemia: A Case Report

PubMed Central

HAYASHI, Shihori; MAEHARA, Taketoshi; MUKAWA, Maki; AOYAGI, Masaru; YOSHINO, Yoshikazu; NEMOTO, Shigeru; ONO, Toshiaki; OHNO, Kikuo

2014-01-01

Ruptured intracranial aneurysms are rare in the pediatric population compared to adults. This has incited considerable discussion on how to treat children with this condition. Here, we report a child with a ruptured saccular basilar artery aneurysm that was successfully treated with coil embolization. A 12-year-old boy with acute lymphoblastic leukemia and accompanying abdominal candidiasis after chemotherapy suddenly complained of a severe headache and suffered consciousness disturbance moments later. Computed tomography scans and cerebral angiography demonstrated acute hydrocephalus and subarachnoid hemorrhage caused by saccular basilar artery aneurysm rupture. External ventricular drainage was performed immediately. Because the patient was in severe condition and did not show remarkable signs of central nervous system infection in cerebrospinal fluid studies, we applied endovascular treatment for the ruptured saccular basilar artery aneurysm, which was successfully occluded with coils. The patient recovered without new neurological deficits after ventriculoperitoneal shunting. Recent reports indicate that both endovascular and microsurgical techniques can be used to effectively treat ruptured cerebral aneurysms in pediatric patients. A minimally invasive endovascular treatment was effective in the present case, but long-term follow-up will be necessary to confirm the efficiency of endovascular treatment for children with ruptured saccular basilar artery aneurysms. PMID:24257487

Successful coil embolization of a ruptured basilar artery aneurysm in a child with leukemia: a case report.

PubMed

Hayashi, Shihori; Maehara, Taketoshi; Mukawa, Maki; Aoyagi, Masaru; Yoshino, Yoshikazu; Nemoto, Shigeru; Ono, Toshiaki; Ohno, Kikuo

2014-01-01

Ruptured intracranial aneurysms are rare in the pediatric population compared to adults. This has incited considerable discussion on how to treat children with this condition. Here, we report a child with a ruptured saccular basilar artery aneurysm that was successfully treated with coil embolization. A 12-year-old boy with acute lymphoblastic leukemia and accompanying abdominal candidiasis after chemotherapy suddenly complained of a severe headache and suffered consciousness disturbance moments later. Computed tomography scans and cerebral angiography demonstrated acute hydrocephalus and subarachnoid hemorrhage caused by saccular basilar artery aneurysm rupture. External ventricular drainage was performed immediately. Because the patient was in severe condition and did not show remarkable signs of central nervous system infection in cerebrospinal fluid studies, we applied endovascular treatment for the ruptured saccular basilar artery aneurysm, which was successfully occluded with coils. The patient recovered without new neurological deficits after ventriculoperitoneal shunting. Recent reports indicate that both endovascular and microsurgical techniques can be used to effectively treat ruptured cerebral aneurysms in pediatric patients. A minimally invasive endovascular treatment was effective in the present case, but long-term follow-up will be necessary to confirm the efficiency of endovascular treatment for children with ruptured saccular basilar artery aneurysms.

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.

Investigation of specific interactions between T7 promoter and T7 RNA polymerase by force spectroscopy using atomic force microscope.

PubMed

Zhang, Xiaojuan; Yao, Zhixuan; Duan, Yanting; Zhang, Xiaomei; Shi, Jinsong; Xu, Zhenghong

2018-01-11

The specific recognition and binding of promoter and RNA polymerase is the first step of transcription initiation in bacteria and largely determines transcription activity. Therefore, direct analysis of the interaction between promoter and RNA polymerase in vitro may be a new strategy for promoter characterization, to avoid interference due to the cell's biophysical condition and other regulatory elements. In the present study, the specific interaction between T7 promoter and T7 RNA polymerase was studied as a model system using force spectroscopy based on atomic force microscope (AFM). The specific interaction between T7 promoter and T7 RNA polymerase was verified by control experiments, and the rupture force in this system was measured as 307.2 ± 6.7 pN. The binding between T7 promoter mutants with various promoter activities and T7 RNA polymerase was analyzed. Interaction information including rupture force, rupture distance and binding percentage were obtained in vitro , and reporter gene expression regulated by these promoters was also measured according to a traditional promoter activity characterization method in vivo Using correlation analysis, it was found that the promoter strength characterized by reporter gene expression was closely correlated with rupture force and the binding percentage by force spectroscopy. These results indicated that the analysis of the interaction between promoter and RNA polymerase using AFM-based force spectroscopy was an effective and valid approach for the quantitative characterization of promoters. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

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.

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

Hofmann, R.; Hartung, R.; Geissdoerfer, K.A.

Laser energy of a Nd-YAG laser (1064 nm. wave length, 8 nsec pulse duration) was directed against various tissue cultures and the urothelium of the ureter, bladder and kidney parenchyma in pigs. Single pulse energy was 50 to 120 mJ with a repetition rate of 20 Hz. Urothelium and kidney parenchyma were irradiated in seven pigs. Tissue samples were examined histologically and electron microscopically directly, two, four, eight and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small rupture cone of 40 micron. depth. No thermic effects or necrosis resulted, so that no harmmore » is to be expected with unintentional irradiation during laser stone disintegration.« less

Poromechanics of stick-slip frictional sliding and strength recovery on tectonic faults

DOE PAGES

Scuderi, Marco M.; Carpenter, Brett M.; Johnson, Paul A.; ...

2015-10-22

Pore fluids influence many aspects of tectonic faulting including frictional strength aseismic creep and effective stress during the seismic cycle. But, the role of pore fluid pressure during earthquake nucleation and dynamic rupture remains poorly understood. Here we report on the evolution of pore fluid pressure and porosity during laboratory stick-slip events as an analog for the seismic cycle. We sheared layers of simulated fault gouge consisting of glass beads in a double-direct shear configuration under true triaxial stresses using drained and undrained fluid conditions and effective normal stress of 5–10 MPa. Shear stress was applied via a constant displacementmore » rate, which we varied in velocity step tests from 0.1 to 30 µm/s. Here, we observe net pore pressure increases, or compaction, during dynamic failure and pore pressure decreases, or dilation, during the interseismic period, depending on fluid boundary conditions. In some cases, a brief period of dilation is attendant with the onset of dynamic stick slip. Our data show that time-dependent strengthening and dynamic stress drop increase with effective normal stress and vary with fluid conditions. For undrained conditions, dilation and preseismic slip are directly related to pore fluid depressurization; they increase with effective normal stress and recurrence time. Microstructural observations confirm the role of water-activated contact growth and shear-driven elastoplastic processes at grain junctions. These results indicate that physicochemical processes acting at grain junctions together with fluid pressure changes dictate stick-slip stress drop and interseismic creep rates and thus play a key role in earthquake nucleation and rupture propagation.« less

Spontaneous rupture of the ascending aorta.

PubMed

Bin Mahmood, Syed Usman; Ulrich, Andrew; Safdar, Basmah; Geirsson, Arnar; Mangi, Abeel A

2018-02-01

Nontraumatic, spontaneous rupture of the ascending aorta is rare and the etiology is largely unknown. We reviewed seven patients from our institution, with no known aortic disease or hereditary connective tissue disorder that presented with spontaneous ascending aortic rupture from 2012 to 2017. Most patients presented with non-radiating chest pain along with hypertension (71.4%). The mean ascending aortic diameter at rupture was 4.60 ± 0.62 cm. The median door-to-operating room time was 2.58 h, resulting from effective implementation of an aortic emergency protocol. There were no operative mortalities. In patients with ascending aortic rupture, aortic diameter may not always correlate with the risk of rupture. Rapid diagnosis combined with a multidisciplinary approach is vital for the successful management of these high-risk patients. © 2018 Wiley Periodicals, Inc.

The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

NASA Technical Reports Server (NTRS)

Mackay, R. A.; Maier, R. D.

1982-01-01

Constant load creep rupture tests were performed on MAR-M247 single crystals at 724 MPa and 774 C where the effect of anisotropy is prominent. The initial orientations of the specimens as well as the final orientations of selected crystals after stress rupture testing were determined by the Laue back-reflection X-ray technique. The stress rupture lives of the MAR-M247 single crystals were found to be largely determined by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited the shortest stress rupture lives, whereas crystals requiring little or no rotations exhibited the lowest minimum creep rates, and consequently, the longest stress rupture lives.

Effect of posterior cruciate ligament rupture on the radial displacement of lateral meniscus.

PubMed

Lei, Pengfei; Sun, Rongxin; Hu, Yihe; Li, Kanghua; Liao, Zhan

2015-06-01

The relationship between lateral meniscus tear and posterior cruciate ligament injury is not well understood. The present study aims to investigate and assess the effect of posterior cruciate ligament rupture on lateral meniscus radial displacement at different flexion angles under static loading conditions. Twelve fresh human cadaveric knee specimens were divided into four groups such as posterior cruciate ligament intact, anterolateral band rupture, posteromedial band rupture and posterior cruciate ligament complete rupture groups, according to the purpose and order of testing. Radial displacement of lateral meniscus was measured under different loads (200-1000N) at 0°, 30°, 60°, and 90° of knee flexion. Compared with posterior cruciate ligament intact group, the displacement values of lateral meniscus in anterolateral band rupture group increased at 0° flexion with 600N, 800N, and 1000N and at 30°, 60° and 90° flexion under all loading conditions. Posteromedial band rupture group exhibited higher displacement at 0° flexion under all loading conditions, at 30° and 60° flexion with 600, 800N and 1000N, and at 90° flexion with 400N, 600N, 800N, and 1000N than the posterior cruciate ligament intact group. The posterior cruciate ligament complete rupture group had a higher displacement value of lateral medial meniscus at 0°, 30°, 60° and 90° flexion under all loading conditions, as compared to the posterior cruciate ligament intact group. The study concludes that partial and complete rupture of the posterior cruciate ligament can trigger the increase of radial displacement on lateral meniscus. Copyright © 2015 Elsevier Ltd. All rights reserved.

The 12 June 2017 Mw 6.3 Lesvos Island (Aegean Sea) earthquake: Slip model and directivity estimated with finite-fault inversion

NASA Astrophysics Data System (ADS)

Kiratzi, Anastasia

2018-01-01

On 12 June 2017 (UTC 12:28:38.26) a magnitude Mw 6.3 earthquake occurred offshore Lesvos Island in SE Aegean Sea, which was widely felt, caused 1 fatality, and partially ruined the village of Vrisa on the south-eastern coast of the island. I invert broad band and strong motion waveforms from regional stations to obtain the source model and the distribution of slip onto the fault plane. The hypocentre is located at a depth of 7 km in the upper crust. The mainshock ruptured a WNW-ESE striking, SW dipping, normal fault, projecting offshore and bounding the Lesvos Basin. The strongest and most aftershocks clustered away from the hypocentre, at the eastern edge of the activated area. This cluster indicates the activation of a different fault segment, exhibiting sinistral strike-slip motions, along a plane striking WNW-ESE. The slip of the mainshock is confined in a single large asperity, WNW from the hypocentre, with dimensions 20 km × 10 km along fault strike and dip, respectively. The average slip of the asperity is 50 cm and the peak slip is 1 m. The rupture propagated unilaterally towards WNW to the coastline of Lesvos island at a relatively high speed ( 3.1 km/s). The imaged slip model and forward modelling was used to calculate peak ground velocities (PGVs) in the near-field. The damage pattern produced by this earthquake, especially in the village of Vrisa is compatible with the combined effect of rupture directivity, proximity to the slip patch and the fault edge, spectral content of motions, and local site conditions.

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.

CyberShake-derived ground-motion prediction models for the Los Angeles region with application to earthquake early warning

USGS Publications Warehouse

Bose, Maren; Graves, Robert; Gill, David; Callaghan, Scott; Maechling, Phillip J.

2014-01-01

Real-time applications such as earthquake early warning (EEW) typically use empirical ground-motion prediction equations (GMPEs) along with event magnitude and source-to-site distances to estimate expected shaking levels. In this simplified approach, effects due to finite-fault geometry, directivity and site and basin response are often generalized, which may lead to a significant under- or overestimation of shaking from large earthquakes (M > 6.5) in some locations. For enhanced site-specific ground-motion predictions considering 3-D wave-propagation effects, we develop support vector regression (SVR) models from the SCEC CyberShake low-frequency (<0.5 Hz) and broad-band (0–10 Hz) data sets. CyberShake encompasses 3-D wave-propagation simulations of >415 000 finite-fault rupture scenarios (6.5 ≤ M ≤ 8.5) for southern California defined in UCERF 2.0. We use CyberShake to demonstrate the application of synthetic waveform data to EEW as a ‘proof of concept’, being aware that these simulations are not yet fully validated and might not appropriately sample the range of rupture uncertainty. Our regression models predict the maximum and the temporal evolution of instrumental intensity (MMI) at 71 selected test sites using only the hypocentre, magnitude and rupture ratio, which characterizes uni- and bilateral rupture propagation. Our regression approach is completely data-driven (where here the CyberShake simulations are considered data) and does not enforce pre-defined functional forms or dependencies among input parameters. The models were established from a subset (∼20 per cent) of CyberShake simulations, but can explain MMI values of all >400 k rupture scenarios with a standard deviation of about 0.4 intensity units. We apply our models to determine threshold magnitudes (and warning times) for various active faults in southern California that earthquakes need to exceed to cause at least ‘moderate’, ‘strong’ or ‘very strong’ shaking in the Los Angeles (LA) basin. These thresholds are used to construct a simple and robust EEW algorithm: to declare a warning, the algorithm only needs to locate the earthquake and to verify that the corresponding magnitude threshold is exceeded. The models predict that a relatively moderate M6.5–7 earthquake along the Palos Verdes, Newport-Inglewood/Rose Canyon, Elsinore or San Jacinto faults with a rupture propagating towards LA could cause ‘very strong’ to ‘severe’ shaking in the LA basin; however, warning times for these events could exceed 30 s.

Cross cultural adaptation of the Achilles tendon Total Rupture Score with reliability, validity and responsiveness evaluation.

PubMed

Carmont, Michael R; Silbernagel, Karin Grävare; Nilsson-Helander, Katarina; Mei-Dan, Omer; Karlsson, Jon; Maffulli, Nicola

2013-06-01

The Achilles tendon Total Rupture Score (ATRS) was developed because of the need for a reliable, valid and sensitive instrument to evaluate symptoms and their effects on physical activity in patients following either conservative or surgical management of an Achilles tendon rupture. Prior to using the score in larger randomized trial in an English-speaking population, we decided to perform reliability, validity and responsiveness evaluations of the English version of the ATRS. Even though the score was published in English, the actual English version has not be validated and compared to the results of the Swedish version. From 2009 to 2010, all patients who received treatment for Achilles tendon rupture were followed up using the English version of the ATRS. Patients were asked to complete the score at 3, 6 and 12 months following treatment for Achilles tendon rupture. The ATRS was completed on arrival in the outpatient clinic and again following consultation. The outcomes of 49 (13 female and 36 male) patients were assessed. The mean (SD) age was 49 (12) years, and 27 patients had treatment for a left-sided rupture, 22 the right. All patients received treatment for ruptured Achilles tendons: 38 acute percutaneous repair, 1 open repair, 5 an Achilles tendon reconstruction using a Peroneus Brevis tendon transfer for delayed presentation, 1 gracilis augmented repair for re-rupture and 4 non-operative treatment for mid-portion rupture. The English version of ATRS was shown to have overall excellent reliability (ICC = 0.986). There was no significant difference between the results with the English version and the Swedish version when compared at the 6-month- or 12-month (n.s.) follow-up appointments. The effect size was 0.93. The minimal detectable change was 6.75 points. The ATRS was culturally adapted to English and shown to be a reliable, valid and responsive method of testing functional outcome following an Achilles tendon rupture.

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.

Effects of Thermal Treatment on Tensile Creep and Stress-Rupture Behavior of Hi-Nicalon SiC Fibers

NASA Technical Reports Server (NTRS)

Yun, H. M.; Goldsby, J. C.; Dicarlo, J. A.

1995-01-01

Tensile creep and stress-rupture studies were conducted on Hi-Nicalon SiC fibers at 1200 and 1400 C in argon and air. Examined were as-received fibers as well as fibers annealed from 1400 to 1800 C for 1 hour in argon before testing. The creep and rupture results for these annealed fibers were compared to those of the as-received fibers to determine the effects of annealing temperature, test temperature, and test environment. Argon anneals up to 1500 C degrade room temperature strength of Hi-Nicalon fibers, but improve fiber creep resistance in argon or air by as much as 100% with no significant degradation in rupture strength. Argon anneals above 1500 C continue to improve fiber creep resistance when tested in argon, but significantly degrade creep resistance and rupture strength when tested in air. Decrease in creep resistance in air is greater at 1200 C than at 1400 C. Mechanisms are suggested for the observed behavior.

Simulated ground motion in Santa Clara Valley, California, and vicinity from M≥6.7 scenario earthquakes

USGS Publications Warehouse

Harmsen, Stephen C.; Hartzell, Stephen

2008-01-01

Models of the Santa Clara Valley (SCV) 3D velocity structure and 3D finite-difference software are used to predict ground motions from scenario earthquakes on the San Andreas (SAF), Monte Vista/Shannon, South Hayward, and Calaveras faults. Twenty different scenario ruptures are considered that explore different source models with alternative hypocenters, fault dimensions, and rupture velocities and three different velocity models. Ground motion from the full wave field up to 1 Hz is exhibited as maps of peak horizontal velocity and pseudospectral acceleration at periods of 1, 3, and 5 sec. Basin edge effects and amplification in sedimentary basins of the SCV are observed that exhibit effects from shallow sediments with relatively low shear-wave velocity (330 m/sec). Scenario earthquakes have been simulated for events with the following magnitudes: (1) M 6.8–7.4 Calaveras sources, (2) M 6.7–6.9 South Hayward sources, (3) M 6.7 Monte Vista/Shannon sources, and (4) M 7.1–7.2 Peninsula segment of the SAF sources. Ground motions are strongly influenced by source parameters such as rupture velocity, rise time, maximum depth of rupture, hypocenter, and source directivity. Cenozoic basins also exert a strong influence on ground motion. For example, the Evergreen Basin on the northeastern side of the SCV is especially responsive to 3–5-sec energy from most scenario earthquakes. The Cupertino Basin on the southwestern edge of the SCV tends to be highly excited by many Peninsula and Monte Vista fault scenarios. Sites over the interior of the Evergreen Basin can have long-duration coda that reflect the trapping of seismic energy within this basin. Plausible scenarios produce predominantly 5-sec wave trains with greater than 30 cm/sec sustained ground-motion amplitude with greater than 30 sec duration within the Evergreen Basin.

Expanding CyberShake Physics-Based Seismic Hazard Calculations to Central California

NASA Astrophysics Data System (ADS)

Silva, F.; Callaghan, S.; Maechling, P. J.; Goulet, C. A.; Milner, K. R.; Graves, R. W.; Olsen, K. B.; Jordan, T. H.

2016-12-01

As part of its program of earthquake system science, the Southern California Earthquake Center (SCEC) has developed a simulation platform, CyberShake, to perform physics-based probabilistic seismic hazard analysis (PSHA) using 3D deterministic wave propagation simulations. CyberShake performs PSHA by first simulating a tensor-valued wavefield of Strain Green Tensors. CyberShake then takes an earthquake rupture forecast and extends it by varying the hypocenter location and slip distribution, resulting in about 500,000 rupture variations. Seismic reciprocity is used to calculate synthetic seismograms for each rupture variation at each computation site. These seismograms are processed to obtain intensity measures, such as spectral acceleration, which are then combined with probabilities from the earthquake rupture forecast to produce a hazard curve. Hazard curves are calculated at seismic frequencies up to 1 Hz for hundreds of sites in a region and the results interpolated to obtain a hazard map. In developing and verifying CyberShake, we have focused our modeling in the greater Los Angeles region. We are now expanding the hazard calculations into Central California. Using workflow tools running jobs across two large-scale open-science supercomputers, NCSA Blue Waters and OLCF Titan, we calculated 1-Hz PSHA results for over 400 locations in Central California. For each location, we produced hazard curves using both a 3D central California velocity model created via tomographic inversion, and a regionally averaged 1D model. These new results provide low-frequency exceedance probabilities for the rapidly expanding metropolitan areas of Santa Barbara, Bakersfield, and San Luis Obispo, and lend new insights into the effects of directivity-basin coupling associated with basins juxtaposed to major faults such as the San Andreas. Particularly interesting are the basin effects associated with the deep sediments of the southern San Joaquin Valley. We will compare hazard estimates from the 1D and 3D models, summarize the challenges of expanding CyberShake to a new geographic region, and describe our future CyberShake plans.

Holocene activity and seismogenic capability of intraplate thrusts: Insights from the Pampean Ranges, Argentina

NASA Astrophysics Data System (ADS)

Costa, Carlos H.; Owen, Lewis A.; Ricci, Walter R.; Johnson, William J.; Halperin, Alan D.

2018-07-01

Trench excavations across the El Molino fault in the southeastern Pampean Ranges of central-western Argentina have revealed a deformation zone composed of opposite-verging thrusts that deform a succession of Holocene sediments. The west-verging thrusts place Precambrian basement over Holocene proximal scarp-derived deposits, whereas the east-verging thrusts form an east-directed fault-propagation fold that deforms colluvium, fluvial and aeolian deposits. Ages for exposed fault-related deposits range from 7.1 ± 0.4 to 0.3 ka. Evidence of surface deformation suggests multiple rupture events with related scarp-derived deposits and a minimum of three surface ruptures younger than 7.1 ± 0.4 ka, the last rupture event being younger than 1 ka. Shortening rates of 0.7 ± 0.2 mm/a are near one order of magnitude higher than those estimated for the faults bounding neighboring crustal blocks and are considered high for this intraplate setting. These ground-rupturing crustal earthquakes are estimated to be of magnitude Mw ≥ 7.0, a significant discrepancy with the magnitudes Mw < 6.5 recorded in the seismic catalog of this region at present with low to moderate seismicity. Results highlight the relevance of identifying primary surface ruptures as well as the seismogenic potential of thrust faults in seemingly stable continental interiors.

Compound earthquakes on a bimaterial interface and implications for rupture mechanics

NASA Astrophysics Data System (ADS)

Wang, E.; Rubin, A. M.

2012-12-01

Earthquake ruptures on the San Andreas are affected by the material contrast across the fault. Previous observations of microearthquakes in the northern creeping section have found strong signals of asymmetry in both rupture directivity (preferential propagation to the SE; Wang & Rubin, 2011), and aftershock asymmetry (many more to the NW, on timescales from 10 to 1000 s; Rubin & Gillard, 2000; Rubin, 2002). To understand the aftershock asymmetry, Rubin & Ampuero [2007] simulated slip-weakening ruptures on a bimaterial interface and observed differences in the timescales for the two edges to experience their peak stress after being slowed by barriers. While the barrier on the "positive" side (SE in the case of the San Andreas fault) reached the peak stress almost instantaneously, the "negative" side (NW) has to wait for the arrival of the P-wave stopping phase from the opposite end. For a 100 m main event the delay between the two potential ruptures is 20 ms, which may be long enough for the secondary rupture to be observed as a distinct subevent. A second possible source of subevent asymmetry is that when slowed by barriers, a significant tensile stress pulse propagates in the positive but not the negative direction. The events in the region where previous asymmetries were found have high spatial density and similar focal mechanisms, which makes it possible to use an Empirical Green's Function's method to do a comprehensive search. About 200 candidate compound events were identified in an 8300-event catalog from 1984 to 2009. Most delays between the two subevents cluster around the shear-wave transit time over the subevent separation, although with considerable scatter. For subevents separated by 0.7 to 2 estimated mainshock radii (the same spatial separation found by Rubin [2002] to maximize the longer-term aftershock asymmetry), about twice as many second events occurred on the SE (positive) side of the first, and the origin time delays also tend to be shorter for SE aftershocks. One interpretation is that these subevents represent the events "missing" from the aftershock population because they became part of the mainshock.

Correlation between atmospheric pressure changes and abdominal aortic aneurysm rupture: results of a single-center study.

PubMed

Molacek, Jiri; Treska, Vladislav; Kasik, Miroslav; Houdek, Karel; Baxa, Jan

2013-09-01

There is much interest in all factors that influence the etiopathogenesis of abdominal aortic aneurysm (AAA) rupture. Apart from the well-established factors such as arterial hypertension, smoking, age, and genetic predisposition, less common factors that may play a role in the mechanism of the rupture are the subject of much discussion. These include atmospheric conditions, temperature, and atmospheric pressure. We conducted this study to investigate the effects of the absolute value of atmospheric pressure and its changes on the frequency of AAA rupture. We retrospectively examined 54 patients who underwent treatment for a ruptured AAA at the Clinic of Surgery in the University Hospital in Pilsen between 1 January 2005 and 31 December 2009. We collected data on the atmospheric pressure in this period from the Czech Hydrometeorological Institute in Pilsen. We did not find a significant difference in atmospheric pressure values between the days when the rupture occurred versus the other days (p < 0.5888). Moreover, we did not find significant changes in the atmospheric pressure during the 48 h preceding the rupture (Student's test p < 0.4434) versus the day of rupture or in the mean atmospheric pressure in that month. These findings suggest that atmospheric pressure and its changes do not affect the pathogenesis of AAA rupture.

Experimental study of Siphon breaker about size effect in real scale reactor design

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

Kang, S. H.; Ahn, H. S.; Kim, J. M.

2012-07-01

Rupture accident within the pipe of a nuclear reactor is one of the main causes of a loss of coolant accident (LOCA). Siphon-breaking is a passive method that can prevent a LOCA. In this study, either a line or a hole is used as a siphon-breaker, and the effect of various parameters, such as the siphon-breaker size, pipe rupture point, pipe rupture size, and the presence of an orifice, are investigated using an experimental facility similar in size to a full-scale reactor. (authors)

Incidence of plantar fascia ruptures following corticosteroid injection.

PubMed

Kim, Chul; Cashdollar, Michael R; Mendicino, Robert W; Catanzariti, Alan R; Fuge, LaDonna

2010-12-01

Plantar fasciitis is commonly treated with corticosteroid injections to decrease pain and inflammation. Therapeutic benefits often vary in terms of efficacy and duration. Rupture of the plantar fascia has been reported as a possible complication following corticosteroid injection. A retrospective chart review of 120 patients who received corticosteroid injection for plantar fasciitis was performed at the authors' institution to determine the incidence of plantar fascia rupture. The plantar fascia rupture was diagnosed clinically and confirmed with magnetic resonance imaging. Various factors were analyzed, including the number of injections, interval between injections, body mass index (BMI), and activity level. Four patients (2.4%) consequently experienced plantar fascia rupture following an average of 2.67 injections. The average BMI of these patients was 38.6 kg/m². The authors conclude that corticosteroid injection therapy appears to be a safe and effective form of nonoperative treatment with minimal complications and a relatively low incident of plantar fascia rupture.

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.

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.

Directivity models produced for the Next Generation Attenuation West 2 (NGA-West 2) project

USGS Publications Warehouse

Spudich, Paul A.; Watson-Lamprey, Jennie; Somerville, Paul G.; Bayless, Jeff; Shahi, Shrey; Baker, Jack W.; Rowshandel, Badie; Chiou, Brian

2012-01-01

Five new directivity models are being developed for the NGA-West 2 project. All are based on the NGA-West 2 data base, which is considerably expanded from the original NGA-West data base, containing about 3,000 more records from earthquakes having finite-fault rupture models. All of the new directivity models have parameters based on fault dimension in km, not normalized fault dimension. This feature removes a peculiarity of previous models which made them inappropriate for modeling large magnitude events on long strike-slip faults. Two models are explicitly, and one is implicitly, 'narrowband' models, in which the effect of directivity does not monotonically increase with spectral period but instead peaks at a specific period that is a function of earthquake magnitude. These narrowband models' functional forms are capable of simulating directivity over a wider range of earthquake magnitude than previous models. The functional forms of the five models are presented.

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

Effect of Time and Temperature on Transformation Toughened Zirconias.

DTIC Science & Technology

1987-06-01

room temperature. High temperature mechanical tests performed vere stress rupture and stepped temperature stress rupture. The results of the tests...tetragonal precipitates will spontaneously transform to the monoclinic phae due to the lattice mismatch stress if they become larger than about 0.2 on, with...specimens, including fast fracture and fracture toughness testing. High temper- ture testing consisting of stress rupture and stepped temperature stress

Bifurcation of rupture path by linear and cubic damping force

NASA Astrophysics Data System (ADS)

Dennis L. C., C.; Chew X., Y.; Lee Y., C.

2014-06-01

Bifurcation of rupture path is studied for the effect of linear and cubic damping. Momentum equation with Rayleigh factor was transformed into ordinary differential form. Bernoulli differential equation was obtained and solved by the separation of variables. Analytical or exact solutions yielded the bifurcation was visible at imaginary part when the wave was non dispersive. For the dispersive wave, bifurcation of rupture path was invisible.

3-D simulations of M9 earthquakes on the Cascadia Megathrust: Key parameters and uncertainty

USGS Publications Warehouse

Wirth, Erin; Frankel, Arthur; Vidale, John; Marafi, Nasser A.; Stephenson, William J.

2017-01-01

Geologic and historical records indicate that the Cascadia subduction zone is capable of generating large, megathrust earthquakes up to magnitude 9. The last great Cascadia earthquake occurred in 1700, and thus there is no direct measure on the intensity of ground shaking or specific rupture parameters from seismic recordings. We use 3-D numerical simulations to generate broadband (0-10 Hz) synthetic seismograms for 50 M9 rupture scenarios on the Cascadia megathrust. Slip consists of multiple high-stress drop subevents (~M8) with short rise times on the deeper portion of the fault, superimposed on a background slip distribution with longer rise times. We find a >4x variation in the intensity of ground shaking depending upon several key parameters, including the down-dip limit of rupture, the slip distribution and location of strong-motion-generating subevents, and the hypocenter location. We find that extending the down-dip limit of rupture to the top of the non-volcanic tremor zone results in a ~2-3x increase in peak ground acceleration for the inland city of Seattle, Washington, compared to a completely offshore rupture. However, our simulations show that allowing the rupture to extend to the up-dip limit of tremor (i.e., the deepest rupture extent in the National Seismic Hazard Maps), even when tapering the slip to zero at the down-dip edge, results in multiple areas of coseismic coastal uplift. This is inconsistent with coastal geologic evidence (e.g., buried soils, submerged forests), which suggests predominantly coastal subsidence for the 1700 earthquake and previous events. Defining the down-dip limit of rupture as the 1 cm/yr locking contour (i.e., mostly offshore) results in primarily coseismic subsidence at coastal sites. We also find that the presence of deep subevents can produce along-strike variations in subsidence and ground shaking along the coast. Our results demonstrate the wide range of possible ground motions from an M9 megathrust earthquake in Cascadia, and the potential to further constrain key rupture parameters using geologic and geophysical observations, ultimately improving our estimation of seismic hazard associated with the Cascadia megathrust.

Are Physics-Based Simulators Ready for Prime Time? Comparisons of RSQSim with UCERF3 and Observations.

NASA Astrophysics Data System (ADS)

Milner, K. R.; Shaw, B. E.; Gilchrist, J. J.; Jordan, T. H.

2017-12-01

Probabilistic seismic hazard analysis (PSHA) is typically performed by combining an earthquake rupture forecast (ERF) with a set of empirical ground motion prediction equations (GMPEs). ERFs have typically relied on observed fault slip rates and scaling relationships to estimate the rate of large earthquakes on pre-defined fault segments, either ignoring or relying on expert opinion to set the rates of multi-fault or multi-segment ruptures. Version 3 of the Uniform California Earthquake Rupture Forecast (UCERF3) is a significant step forward, replacing expert opinion and fault segmentation with an inversion approach that matches observations better than prior models while incorporating multi-fault ruptures. UCERF3 is a statistical model, however, and doesn't incorporate the physics of earthquake nucleation, rupture propagation, and stress transfer. We examine the feasibility of replacing UCERF3, or components therein, with physics-based rupture simulators such as the Rate-State Earthquake Simulator (RSQSim), developed by Dieterich & Richards-Dinger (2010). RSQSim simulations on the UCERF3 fault system produce catalogs of seismicity that match long term rates on major faults, and produce remarkable agreement with UCERF3 when carried through to PSHA calculations. Averaged over a representative set of sites, the RSQSim-UCERF3 hazard-curve differences are comparable to the small differences between UCERF3 and its predecessor, UCERF2. The hazard-curve agreement between the empirical and physics-based models provides substantial support for the PSHA methodology. RSQSim catalogs include many complex multi-fault ruptures, which we compare with the UCERF3 rupture-plausibility metrics as well as recent observations. Complications in generating physically plausible kinematic descriptions of multi-fault ruptures have thus far prevented us from using UCERF3 in the CyberShake physics-based PSHA platform, which replaces GMPEs with deterministic ground motion simulations. RSQSim produces full slip/time histories that can be directly implemented as sources in CyberShake, without relying on the conditional hypocenter and slip distributions needed for the UCERF models. We also compare RSQSim with time-dependent PSHA calculations based on multi-fault renewal models.

The 7.9 Denali Fault, Alaska Earthquake of November 3, 2002: Aftershock Locations, Moment Tensors and Focal Mechanisms from the Regional Seismic Network Data

NASA Astrophysics Data System (ADS)

Ratchkovski, N. A.; Hansen, R. A.; Kore, K. R.

2003-04-01

The largest earthquake ever recorded on the Denali fault system (magnitude 7.9) struck central Alaska on November 3, 2002. It was preceded by a magnitude 6.7 earthquake on October 23. This earlier earthquake and its zone of aftershocks were located ~20 km to the west of the 7.9 quake. Aftershock locations and surface slip observations from the 7.9 quake indicate that the rupture was predominately unilateral in the eastward direction. The geologists mapped a ~300-km-long rupture and measured maximum offsets of 8.8 meters. The 7.9 event ruptured three different faults. The rupture began on the northeast trending Susitna Glacier Thrust fault, a splay fault south of the Denali fault. Then the rupture transferred to the Denali fault and propagated eastward for 220 km. At about 143W the rupture moved onto the adjacent southeast-trending Totschunda fault and propagated for another 55 km. The cumulative length of the 6.7 and 7.9 aftershock zones along the Denali and Totschunda faults is about 380 km. The earthquakes were recorded and processed by the Alaska Earthquake Information Center (AEIC). The AEIC acquires and processes data from the Alaska Seismic Network, consisting of over 350 seismograph stations. Nearly 40 of these sites are equipped with the broad-band sensors, some of which also have strong motion sensors. The rest of the stations are either 1 or 3-component short-period instruments. The data from these stations are collected, processed and archived at the AEIC. The AEIC staff installed a temporary seismic network of 6 instruments following the 6.7 earthquake and an additional 20 stations following the 7.9 earthquake. Prior to the 7.9 Denali Fault event, the AEIC was locating 35 to 50 events per day. After the event, the processing load increased to over 300 events per day during the first week following the event. In this presentation, we will present and interpret the aftershock location patterns, first motion focal mechanism solutions, and regional seismic moment tensors for the larger events. We used the double difference method to relocate aftershocks of both the 6.7 and 7.9 events. The relocated aftershocks indicate complex faulting along the rupture zone. The aftershocks are located not only along the main rupture zone, but also illuminate multiple splay faults north and south of the Denali fault. We calculated principal stress directions along the Denali fault both before and after the 7.9 event from the focal mechanisms. The stress orientations before and after the event are nearly identical. The maximum horizontal compressive stress is nearly normal to the trace of the Denali fault and rotates gradually from NW orientation at the western end of the rupture zone to NE orientation near the junction with the Totschunda fault.

Effects of Bounded Fault on Seismic Radiation and Rupture Propagation

NASA Astrophysics Data System (ADS)

Weng, H.; Yang, H.

2016-12-01

It has been suggested that narrow rectangle fault may emit stopping phases that can largely affect seismic radiation and thus rupture propagation, e.g., generation of short-duration pulse-like ruptures. Here we investigate the effects of narrow along-dip rectangle fault (analogously to 2015 Nepal earthquake with 200 km * 40 km) on seismic radiation and rupture propagation through numerical modeling in the framework of the linear slip-weakening friction law. First, we found the critical slip-weakening distance Dc may largely affect the seismic radiation and other source parameters, such as rupture speed, final slip and stress drop. Fixing all other uniform parameters, decreasing Dc could decrease the duration time of slip rate and increase the peak slip rate, thus increase the seismic radiation energy spectrum of slip acceleration. In addition, smaller Dc could lead to larger rupture speed (close to S wave velocity), but smaller stress drop and final slip. The results show that Dc may control the efficiency of far-field radiation. Furthermore, the duration time of slip rate at locations close to boundaries is 1.5 - 4 s less than that in the center of the fault. Such boundary effect is especially remarkable for smaller Dc due to the smaller average duration time of slip rate, which could increase the high-frequency radiation energy and impede low-frequency component near the boundaries from the analysis of energy spectrum of slip acceleration. These results show high frequency energy tends to be radiated near the fault boundaries as long as Dc is small enough. In addition, ruptures are fragile and easy to self-arrest if the width of the seismogenic zone is very narrow. In other words, the sizes of nucleation zone need to be larger to initiate runaway ruptures. Our results show the critical sizes of nucleation zones increase as the widths of seismogenic zones decrease.

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.

Surgical approach to posterior inferior cerebellar artery aneurysms.

PubMed

La Pira, Biagia; Sturiale, Carmelo Lucio; Della Pepa, Giuseppe Maria; Albanese, Alessio

2018-02-01

The far-lateral is a standardised approach to clip aneurysms of the posterior inferior cerebellar artery (PICA). Different variants can be adopted to manage aneurysms that differ in morphology, topography, ruptured status, cerebellar swelling and surgeon preference. We distinguished five paradigmatic approaches aimed to manage aneurysms that are: proximal unruptured; proximal ruptured requiring posterior fossa decompression (PFD); proximal ruptured not requiring PFD; distal unruptured; distal ruptured. Preoperative planning in the setting of PICA aneurysm surgery is of paramount importance to perform an effective and safe procedure, to ensure an adequate PFD and optimal proximal control before aneurysm manipulation.

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?

Effect of water phase transition on dynamic ruptures with thermal pressurization: Numerical simulations with changes in physical properties of water

NASA Astrophysics Data System (ADS)

Urata, Yumi; Kuge, Keiko; Kase, Yuko

2015-02-01

Phase transitions of pore water have never been considered in dynamic rupture simulations with thermal pressurization (TP), although they may control TP. From numerical simulations of dynamic rupture propagation including TP, in the absence of any water phase transition process, we predict that frictional heating and TP are likely to change liquid pore water into supercritical water for a strike-slip fault under depth-dependent stress. This phase transition causes changes of a few orders of magnitude in viscosity, compressibility, and thermal expansion among physical properties of water, thus affecting the diffusion of pore pressure. Accordingly, we perform numerical simulations of dynamic ruptures with TP, considering physical properties that vary with the pressure and temperature of pore water on a fault. To observe the effects of the phase transition, we assume uniform initial stress and no fault-normal variations in fluid density and viscosity. The results suggest that the varying physical properties decrease the total slip in cases with high stress at depth and small shear zone thickness. When fault-normal variations in fluid density and viscosity are included in the diffusion equation, they activate TP much earlier than the phase transition. As a consequence, the total slip becomes greater than that in the case with constant physical properties, eradicating the phase transition effect. Varying physical properties do not affect the rupture velocity, irrespective of the fault-normal variations. Thus, the phase transition of pore water has little effect on dynamic ruptures. Fault-normal variations in fluid density and viscosity may play a more significant role.

3D Ground-Motion Simulations for Magnitude 9 Earthquakes on the Cascadia Megathrust: Sedimentary Basin Amplification, Rupture Directivity, and Ground-Motion Variability

NASA Astrophysics Data System (ADS)

Frankel, A. D.; Wirth, E. A.; Marafi, N.; Vidale, J. E.; Stephenson, W. J.

2017-12-01

We have produced broadband (0-10 Hz) synthetic seismograms for Mw 9 earthquakes on the Cascadia subduction zone by combining synthetics from 3D finite-difference simulations at low frequencies (≤ 1 Hz) and stochastic synthetics at high frequencies (≥ 1 Hz). These synthetic ground motions are being used to evaluate building response, liquefaction, and landslides, as part of the M9 Project of the University of Washington, in collaboration with the U.S. Geological Survey. The kinematic rupture model is composed of high stress drop sub-events with Mw 8, similar to those observed in the Mw 9.0 Tohoku, Japan and Mw 8.8 Maule, Chile earthquakes, superimposed on large background slip with lower slip velocities. The 3D velocity model is based on active and passive-source seismic tomography studies, seismic refraction and reflection surveys, and geologic constraints. The Seattle basin portion of the model has been validated by simulating ground motions from local earthquakes. We have completed 50 3D simulations of Mw 9 earthquakes using a variety of hypocenters, slip distributions, sub-event locations, down-dip limits of rupture, and other parameters. For sites not in deep sedimentary basins, the response spectra of the synthetics for 0.1-6.0 s are similar, on average, to the values from the BC Hydro ground motion prediction equations (GMPE). For periods of 7-10 s, the synthetic response spectra exceed these GMPE, partially due to the shallow dip of the plate interface. We find large amplification factors of 2-5 for response spectra at periods of 1-10 s for locations in the Seattle and Tacoma basins, relative to sites outside the basins. This amplification depends on the direction of incoming waves and rupture directivity. The basin amplification is caused by surface waves generated at basin edges from incoming S-waves, as well as amplification and focusing of S-waves and surface waves by the 3D basin structure. The inter-event standard deviation of response spectral amplitudes from the synthetics is larger for sites nearer the coast, because of their higher sensitivity to the sub-event locations and rupture directivity. The total standard deviations of spectral accelerations from 30 simulations for periods greater than 2 s are similar to those determined in the BC Hydro GMPE from strong-motion recordings in subduction zones.

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.

Biophysics of malarial parasite exit from infected erythrocytes.

PubMed

Chandramohanadas, Rajesh; Park, YongKeun; Lui, Lena; Li, Ang; Quinn, David; Liew, Kingsley; Diez-Silva, Monica; Sung, Yongjin; Dao, Ming; Lim, Chwee Teck; Preiser, Peter Rainer; Suresh, Subra

2011-01-01

Upon infection and development within human erythrocytes, P. falciparum induces alterations to the infected RBC morphology and bio-mechanical properties to eventually rupture the host cells through parasitic and host derived proteases of cysteine and serine families. We used previously reported broad-spectrum inhibitors (E64d, EGTA-AM and chymostatin) to inhibit these proteases and impede rupture to analyze mechanical signatures associated with parasite escape. Treatment of late-stage iRBCs with E64d and EGTA-AM prevented rupture, resulted in no major RBC cytoskeletal reconfiguration but altered schizont morphology followed by dramatic re-distribution of three-dimensional refractive index (3D-RI) within the iRBC. These phenotypes demonstrated several-fold increased iRBC membrane flickering. In contrast, chymostatin treatment showed no 3D-RI changes and caused elevated fluctuations solely within the parasitophorous vacuole. We show that E64d and EGTA-AM supported PV breakdown and the resulting elevated fluctuations followed non-Gaussian pattern that resulted from direct merozoite impingement against the iRBC membrane. Optical trapping experiments highlighted reduced deformability of the iRBC membranes upon rupture-arrest, more specifically in the treatments that facilitated PV breakdown. Taken together, our experiments provide novel mechanistic interpretations on the role of parasitophorous vacuole in maintaining the spherical schizont morphology, the impact of PV breakdown on iRBC membrane fluctuations leading to eventual parasite escape and the evolution of membrane stiffness properties of host cells in which merozoites were irreversibly trapped, recourse to protease inhibitors. These findings provide a comprehensive, previously unavailable, body of information on the combined effects of biochemical and biophysical factors on parasite egress from iRBCs.

Misoprostol for labor induction in women with term premature rupture of membranes: a meta-analysis.

PubMed

Lin, Monique G; Nuthalapaty, Francis S; Carver, Alissa R; Case, Ashley S; Ramsey, Patrick S

2005-09-01

To systematically review published data evaluating the comparative use of misoprostol with placebo/expectant management or oxytocin for labor induction in women with term (> or = 36 weeks of gestation) premature rupture of membranes. PubMed (1966-2005), Ovid (1966-2005), CINAHL, The Cochrane Library, ACP Journal Club, OCLC, abstracts from scientific forums, and bibliographies of published articles were searched using the following keywords: premature rupture of membranes, misoprostol, labor induction, and cervical ripening. Primary authors were contacted directly if the data sought were unavailable or only published in abstract form. Only randomized controlled trials evaluating the efficacy and safety of misoprostol in comparison with placebo or expectant management (n = 6) and oxytocin (n = 9) published in either article or abstract form were analyzed and included in the meta-analysis. Studies were reviewed independently by all authors. Meta-analysis was performed, and the relative risks (RRs) were calculated and pooled for each study outcome. Misoprostol, compared with placebo, significantly increased vaginal delivery less than 12 hours (RR 2.71, 95% confidence interval [CI] 1.87-3.92, P < .001). Misoprostol was similar to oxytocin with respect to vaginal delivery less than 24 hours (RR 1.07, 95% CI 0.88-1.31, P = .50) and less than 12 hours (RR 0.98, 95% CI 0.71-1.35, P = .90). Misoprostol was not associated with an increased risk of tachysystole, hypertonus, or hyperstimulation syndrome when compared with oxytocin and had similar risks for adverse neonatal and maternal outcomes. Misoprostol is an effective and safe agent for induction of labor in women with term premature rupture of membranes. When compared with oxytocin, the risk of contraction abnormalities and the rate of maternal and neonatal complications were similar among the 2 groups.

The ShakeOut earthquake source and ground motion simulations

USGS Publications Warehouse

Graves, R.W.; Houston, Douglas B.; Hudnut, K.W.

2011-01-01

The ShakeOut Scenario is premised upon the detailed description of a hypothetical Mw 7.8 earthquake on the southern San Andreas Fault and the associated simulated ground motions. The main features of the scenario, such as its endpoints, magnitude, and gross slip distribution, were defined through expert opinion and incorporated information from many previous studies. Slip at smaller length scales, rupture speed, and rise time were constrained using empirical relationships and experience gained from previous strong-motion modeling. Using this rupture description and a 3-D model of the crust, broadband ground motions were computed over a large region of Southern California. The largest simulated peak ground acceleration (PGA) and peak ground velocity (PGV) generally range from 0.5 to 1.0 g and 100 to 250 cm/s, respectively, with the waveforms exhibiting strong directivity and basin effects. Use of a slip-predictable model results in a high static stress drop event and produces ground motions somewhat higher than median level predictions from NGA ground motion prediction equations (GMPEs).

Elastic rebound following the Kocaeli earthquake, Turkey, recorded using synthetic aperture radar interferometry

USGS Publications Warehouse

Mayer, Larry; Lu, Zhong

2001-01-01

A basic model incorporating satellite synthetic aperture radar (SAR) interferometry of the fault rupture zone that formed during the Kocaeli earthquake of August 17, 1999, documents the elastic rebound that resulted from the concomitant elastic strain release along the North Anatolian fault. For pure strike-slip faults, the elastic rebound function derived from SAR interferometry is directly invertible from the distribution of elastic strain on the fault at criticality, just before the critical shear stress was exceeded and the fault ruptured. The Kocaeli earthquake, which was accompanied by as much as ∼5 m of surface displacement, distributed strain ∼110 km around the fault prior to faulting, although most of it was concentrated in a narrower and asymmetric 10-km-wide zone on either side of the fault. The use of SAR interferometry to document the distribution of elastic strain at the critical condition for faulting is clearly a valuable tool, both for scientific investigation and for the effective management of earthquake hazard.

Nonintrusive diagnosis of premature ruptured amniotic membranes using a novel polymer.

PubMed

Bornstein, Jacob; Geva, Adam; Solt, Ido; Fait, Vladimir; Schoenfeld, Alex; Shoham, Hadar Kessary; Sobel, Jack

2006-08-01

This article describes the evaluation of the diagnostic efficacy of AL-SENSE panty-liner in detecting premature rupture of membranes (PROM). One hundred and three women attending the labor and delivery ward were enrolled into three groups: women presenting with a vaginal leak of fluid who had not yet been examined; women with overt PROM, and women with no fluid leak. The result of the AL-SENSE strip test was compared with the clinical diagnosis, which was based on direct visualization of the posterior vaginal fornix and cervix, crystallization, and nitrazine tests. AL-SENSE panty-liner test had a sensitivity of 100% and a specificity of 75% in detecting PROM, with an overall agreement of 82.35% between the AL-SENSE test result and the clinical diagnosis. AL-SENSE may be used as a reliable test to rule out PROM and as an effective device to diagnose PROM and differentiate it from urine leak and vulvovaginal candidiasis.

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

Coatings for directional eutectics. [cyclic furnace oxidation tests

NASA Technical Reports Server (NTRS)

Jackson, M. R.; Rairden, J. R.; Hampton, L. V.

1974-01-01

Coating compositions were evaluated for oxidation protection of directionally solidified composite alloy NiTaC-13. These coatings included three NiCrAlY compositions (30-5-1, 25-10-1 and 20-15-1), two FeCrAlY compositions (30-5-1 and 25-10-1), a CoCrAlY composition (25-10-1), and one duplex coating, Ni-35Cr + Al. Duplicate pin samples of each composition were evaluated using two cyclic furnace oxidation tests of 100 hours at 871 C and 500 hours at 1093 C. The two best coatings were Ni-20Cr-15Al-lY and Ni-35Cr + Al. The two preferred coatings were deposited on pins and were evaluated in detail in .05 Mach cyclic burner rig oxidation to 1093 C. The NiCrAlY coating was protective after 830 hours of cycling, while the duplex coating withstood 630 hours. Test bars were coated and cycled for up to 500 hours. Tensile tests indicated no effect of coatings on strength. In 871 C air stress rupture, a degradation was observed for coated relative to bare material. The cycled NiCrAlY coating offered excellent protection with properties superior to the bare cycled NiTaC-13 in 1093 C air stress rupture.

Low-cost directionally-solidified turbine blades, volume 2. [TFE731-3 turbofan engine

NASA Technical Reports Server (NTRS)

Dennis, R. E.; Hoppin, G. S., III; Hurst, L. G.

1979-01-01

An endothermically heated technology was used to manufacture low cost, directionally solidified, uncooled nickel-alloy blades for the TFE731-3 turbofan engine. The MAR-M 247 and MER-M 100+Hf blades were finish processed through heat treatment, machining, and coating operations prior to 150 hour engine tests consisting of the following sequences: (1) 50 hours of simulated cruise cycling (high fatigue evaluation); (2) 50 hours at the maximum continuous power rating (stress rupture endurance (low cycle fatigue). None of the blades visually showed any detrimental effects from the test. This was verified by post test metallurgical evaluation. The specific fuel consumption was reduced by 2.4% with the uncooled blades.

Orientation dependence of the stress rupture properties of Nickel-base superalloy single crystals

NASA Technical Reports Server (NTRS)

Mackay, R. A.

1981-01-01

The influence of orientation of the stress rupture behavior of Mar-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because steady-state creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently a short stress rupture life. A unified analysis was attained for the stress rupture behavior of the Mar-M247 single crystals tested in this study at 774 C and that of the Mar-M200 single crystals tested in a prior study at 760 C. In this analysis, the standard 001-011-111 stereographic triangle was divided into several regions of crystallographic orientation which were rank ordered according to stress rupture life for this temperature regime. This plot indicates that those crystals having orientations within about 25 deg of the 001 exhibited significantly longer lives when their orientations were closer to the 001-011 boundary of the stereographic triangle than to the 001-111 boundary.

Effect of rolling on the high temperature tensile and stress-rupture properties of tungsten fiber-superalloy composites

NASA Technical Reports Server (NTRS)

Petrasek, D. W.

1974-01-01

An investigation was conducted to determine the effects of mechanical working on the 1093 C (2000 F) tensile and stress-rupture strength of tungsten alloy/superalloy composites. Hot pressed composites containing either conventional tungsten lamp filament wire or tungsten-1% ThO2 wire and a nickel base alloy matrix were hot rolled at 1093 C (2000 F). The hot pressed and rolled composite specimens were then tested in tension and stress-rupture at 1093 C (2000 F). Rolling decreased the degree of fiber-matrix reaction as a function of time of exposure at 1093 C (2000 F). The stress-rupture properties of the rolled composites were superior to hot pressed composites containing equivalent diameter fibers. Rolling did not appreciably affect the 1093 C (2000 F) ultimate tensile strength of the composites.

Effect of a Material Contrast on a Dynamic Rupture: 3-D

NASA Astrophysics Data System (ADS)

Harris, R. A.; Day, S. M.

2003-12-01

We use numerical simulations of spontaneously propagating ruptures to examine the effect of a material contrast on earthquake dynamics. We specifically study the case of a lateral contrast whereby the fault is the boundary between two different rock-types. This scenario was previously studied in two-dimensions by Harris and Day [BSSA, 1997], and Andrews and Ben-Zion [JGR, 1997], in addition to subsequent 2-D studies, but it has not been known if the two-dimensional results are applicable to the real three-dimensional world. The addition of the third dimension implies a transition from pure mode II (i.e., plane-strain) to mixed-mode crack dynamics, which is more complicated since in mode II the shear and normal stresses are coupled whereas in mode III (i.e., anti-plane strain) they are not coupled. We use a slip-weakening fracture criterion and examine the effect on an earthquake rupture of material contrasts of up to 50 percent across the fault zone. We find a surprisingly good agreement between our earlier 2-D results, and our 3-D results for along-strike propagation. We find that the analytical solution presented in Harris and Day [BSSA, 1997] does an excellent job at predicting the bilateral, along-strike rupture velocities for the three-dimensional situation. In contrast, the along-dip propagation behaves much as expected for a purely mode-III rupture, with the rupture velocities up-dip and down-dip showing the expected symmetries.

Hepatic rupture

PubMed Central

Zhang, Liang; Wan, DaLong; Zhang, LeLe; Xu, ShiGuo; Xie, HaiYang; Lin, ShengZhang

2018-01-01

Abstract Rationale: Currently, percutaneous catheter drainage (PCD) is regarded as the first-line treatment modality of pyogenic liver abscess. Severe complications associated with PCD were uncommon. Hepatic rupture is an uncommon but life-threatening liver trauma with high mortality. Its management is challenging because a delay in the diagnosis may lead to fatal hemorrhagic shock. To our knowledge, PCD-associated hepatic rupture has never been reported. Patient concerns: We report herein a rare case of PCD-associated hepatic rupture. Its clinical courses and our therapeutic approaches are presented. Moreover, the clinical significance, underlying causes, and current views on severe liver trauma management will be discussed briefly. Diagnoses: A diabetic patient suffering from fever and malaise was diagnosed with a pyogenic liver abscess. PCD was performed because intravenous antibiotics were ineffective. The patient developed a liver rupture following PCD, with clinical and imaging confirmation but without further progression. Interventions: Surgical repair and vascular intervention were both inappropriate. As a result, medical treatments with supportive care were adopted and were found to be effective. Outcomes: The patient's condition improved gradually, with stabilized imaging and laboratory performance. He recovered uneventfully during follow-ups. Lessons: Hepatic rupture should be listed as an extremely rare but severe complication of PCD. Immediate suspicion and effective intervention may avoid an unfavorable consequence. PMID:29480839

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.

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.

Elevated temperature mechanical properties and residual tensile properties of two cast superalloys and several nickel-base oxide dispersion strengthened alloys

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1981-01-01

The elevated temperature tensile, stress-rupture and creep properties and residual tensile properties after creep straining have been determined for two cast superalloys and several wrought Ni-16Cr-4Al-yttria oxide dispersion strengthened (ODS) alloys. The creep behavior of the ODS alloys is similar to that of previously studied ODS nickel alloys. In general, the longitudinal direction is stronger than the long transverse direction, and creep is at least partially due to a diffusional creep mechanism as dispersoid-free zones were observed after creep-rupture testing. The tensile properties of the nickel-base superalloy B-1900 and cobalt-base superalloy MAR-M509 are not degraded by prior elevated temperature creep straining (at least up to 1 pct) between 1144 and 1366 K. On the other hand, the room temperature tensile properties of ODS nickel-base alloys can be reduced by prior creep strains of 0.5 pct or less between 1144 and 1477 K, with the long transverse direction being more susceptible to degradation than the longitudinal direction.

Repair of chronic rupture of the achilles tendon using 2 intratendinous flaps from the proximal gastrocnemius-soleus complex.

PubMed

El Shewy, Mohamed Taha; El Barbary, Hassan Magdy; Abdel-Ghani, Hisham

2009-08-01

Chronic rupture of the Achilles tendon is a surgical challenge, owing to the presence of a gap between the retracted ends, which renders direct repair almost impossible. In this study, 2 intratendinous distally based flaps fashioned from the proximal gastrocnemiussoleus complex are used to bridge the gap between the retracted edges of the ruptured Achilles tendon. The flaps are placed in the same line of pull of the ruptured tendon, in an effort to make the graft mimic the original biomechanics as much as possible. Case series; Level of evidence, 4. Eleven patients (9 male and 2 female) with neglected ruptures of the Achilles tendon with retracted ends were included in this study. Two flaps fashioned from the proximal gastrocnemiussoleus complex were rotated over themselves, passed through the proximal stump, and then securely inserted into a previously prepared bed in the distal stump. The patients were followed up for a period of 6 to 9 years. At the final follow-up, all patients were able to return to their preinjury level of activity within a period of 6 to 9 months. The mean preoperative American Orthopedic Foot and Ankle Society score was 42.27, whereas it was 98.91 at the final follow-up, with a range of 88 (in 1 patient) to 100 points (in 10 patients). All 11 patients showed statistically significant improvement according to the Holz rating system. This technique allows for a bridging of the defect present in chronic ruptures of Achilles tendons, with a minimum of complications and a good final outcome.

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.

'Two go together': Near-simultaneous moment release of two asperities during the 2016 Mw 6.6 Muji, China earthquake

NASA Astrophysics Data System (ADS)

Bie, Lidong; Hicks, Stephen; Garth, Thomas; Gonzalez, Pablo; Rietbrock, Andreas

2018-06-01

On 25 November 2016, a Mw 6.6 earthquake ruptured the Muji fault in western Xinjiang, China. We investigate the earthquake rupture independently using geodetic observations from Interferometric Synthetic Aperture Radar (InSAR) and regional seismic recordings. To constrain the fault geometry and slip distribution, we test different combinations of fault dip and slip direction to reproduce InSAR observations. Both InSAR observations and optimal distributed slip model suggest buried rupture of two asperities separated by a gap of greater than 5 km. Additional seismic gaps exist at the end of both asperities that failed in the 2016 earthquake. To reveal the dynamic history of asperity failure, we inverted regional seismic waveforms for multiple centroid moment tensors and construct a moment rate function. The results show a small centroid time gap of 2.6 s between the two sub-events. Considering the >5 km gap between the two asperities and short time interval, we propose that the two asperities failed near-simultaneously, rather than in a cascading rupture propagation style. The second sub-event locates ∼39 km to the east of the epicenter and the centroid time is at 10.7 s. It leads to an estimate of average velocity of 3.7 km/s as an upper bound, consistent with upper crust shear wave velocity in this region. We interpret that the rupture front is propagating at sub-shear wave velocities, but that the second sub-event has a reduced or asymmetric rupture time, leading to the apparent near-simultaneous moment release of the two asperities.

Monitoring the turbidity and surface temperature changes and effects of the 17 August 1999 earthquake in the Izmit Gulf, Turkey by the Landsat TM/ETM data.

PubMed

Tüfekçi, Kenan; Akman, A Unal

2005-09-01

The temporal turbidity and surface temperature changes and effects of the 17 August 1999 earthquake in the Izmit Gulf, Turkey have been investigated using Landsat TM/ETM data. The gulf is in the Mediterranean-Black Sea transition climatic zone and is partially surrounded by green vegetation cover and degraded and densely urbanized-industrialized areas. Landsat TM/ETM data acquired in 1990-1999 confirms increase in turbidity. Turbidity is always low in the southern part and high in the northern part of the gulf, because the more urbanized and industrialized areas are located in the northern part. The Landsat-7 ETM data acquired in the same year (1999) shows seasonal changes in turbidity. Moreover, the two high turbidity and surface temperature anomalies, one of which is parallel to the 17 August 1999 earthquake surface rupture (east-west) and the other which is in the northwest-southeast direction were mapped from Landsat-5 TM data acquired the day (18.08.1999) following the earthquake in the east end of the gulf. On the basis of turbidity implying the sea bottom movement, it is possible to state that a second rupture in the northwest and southeast direction could have occurred at the sea bottom during the earthquake. The distribution of the seismicity centers and the orientation of the lineaments in the area support this finding.

Incorporating fault zone head wave and direct wave secondary arrival times into seismic tomography: Application at Parkfield, California

NASA Astrophysics Data System (ADS)

Bennington, Ninfa L.; Thurber, Clifford; Peng, Zhigang; Zhang, Haijiang; Zhao, Peng

2013-03-01

We present a three-dimensional (3D) P wave velocity (Vp) model of the Parkfield region that utilizes existing P wave arrival time data, including fault zone head waves (FZHWs), and data from direct wave secondary arrivals (DWSAs). The first-arrival and DWSA travel times are obtained as the global- and local-minimum travel time paths, respectively. The inclusion of FZHWs and DWSAs results in as much as a 5% and a 10% increase in the across-fault velocity contrast, respectively, for the Vp model at Parkfield relative to that of Thurber et al. [2006]. Viewed along strike, three pronounced velocity contrast regions are observed: a pair of strong positive velocity contrasts (SW fast), one NW of the 1966 Parkfield earthquake hypocenter and the other SE of the 2004 Parkfield earthquake hypocenter, and a strong negative velocity contrast (NE fast) between the two hypocenters. The negative velocity contrast partially to entirely encompasses peak coseismic slip estimated in several slip models for the 2004 earthquake, suggesting that the negative velocity contrast played a part in defining the rupture patch of the 2004 Parkfield earthquake. Following Ampuero and Ben-Zion (2008), the pattern of velocity contrasts is consistent with the observed bilateral rupture propagation for the 2004 Parkfield earthquake. Although the velocity contrasts also suggest bilateral rupture propagation for the 1966 Parkfield earthquake, the fault is creeping to the NW here, i.e., exhibiting velocity-strengthening behavior. Thus, it is not surprising that rupture propagated only SE during this event.

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

Okada, Takuya, E-mail: okabone@gmail.com; Frank, Michael, E-mail: michael.frank@egp.aphp.fr; Pellerin, Olivier, E-mail: olivier@pellerin.as

PurposeTo evaluate the safety and efficacy of transarterial embolization of life-threatening arterial rupture in patients with vascular Ehlers–Danlos syndrome (vEDS) in a single tertiary referral center.MethodsWe retrospectively analyzed transarterial embolization for vEDS performed at our institution from 2000 to 2012. The indication of embolization was spontaneous arterial rupture or pseudoaneurysm with acute bleeding. All interventions used a percutaneous approach through a 5F or less introducer sheath. Embolic agents were microcoils and glue in 3 procedures, glue alone in 2, and microcoils alone in 2.ResultsFive consecutive vEDS patients were treated by 7 embolization procedures (4 women, mean age 29.8 years). All proceduresmore » were successfully performed. Two patients required a second procedure for newly arterial lesions at a different site from the first procedure. Four of the five patients were still alive after a mean follow-up of 19.4 (range 1–74.7) months. One patient died of multiple organ failure 2 days after procedure. Minor procedural complications were observed in 3 procedures (43 %), all directly managed during the same session. Remote arterial lesions occurred after 3 procedures (43 %); one underwent a second embolization, and the other 2 were observed conservatively. Puncture site complication was observed in only one procedure (14 %).ConclusionEmbolization for vEDS is a safe and effective method to manage life-threatening arterial rupture.« less

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

The effectiveness of 3D animations to enhance understanding of cranial cruciate ligament rupture.

PubMed

Clements, Dylan N; Broadhurst, Henry; Clarke, Stephen P; Farrell, Michael; Bennett, David; Mosley, John R; Mellanby, Richard J

2013-01-01

Cranial cruciate ligament (CCL) rupture is one of the most important orthopedic diseases taught to veterinary undergraduates. The complexity of the anatomy of the canine stifle joint combined with the plethora of different surgical interventions available for the treatment of the disease means that undergraduate veterinary students often have a poor understanding of the pathophysiology and treatment of CCL rupture. We designed, developed, and tested a three dimensional (3D) animation to illustrate the pertinent clinical anatomy of the stifle joint, the effects of CCL rupture, and the mechanisms by which different surgical techniques can stabilize the joint with CCL rupture. When compared with a non-animated 3D presentation, students' short-term retention of functional anatomy improved although they could not impart a better explanation of how different surgical techniques worked. More students found the animation useful than those who viewed a comparable non-animated 3D presentation. Multiple peer-review testing is required to maximize the usefulness of 3D animations during development. Free and open access to such tools should improve student learning and client understanding through wide-spread uptake and use.

Rupture History of the 2001 Nisqually Washington Earthquake

NASA Astrophysics Data System (ADS)

Xu, Q.; Creager, K. C.; Crosson, R. S.

2001-12-01

We analyze the temporal-spatial rupture history of the magnitude 6.8 February 28, 2001 Nisqually earthquake using about two dozen 3-component strong-motion records from the Pacific Northwest Seismic Network (PNSN) and the USGS National Strong Motion Program (NSMP) network. We employ a finite-fault inversion scheme similar to Hartzell and Heaton [Bull. Seism. Soc. Am., 1983] to recover the slip history. We assume rupture initiates at the epicenter and origin time determined using PNSN P arrival times and a high-resolution 3-D velocity model. Hypocentral depth is 54 km based on our analysis of teleseismic pP-P times and the regional 3-D model. Using the IASP91 standard Earth model to explain the pP-P times gives a depth of 58 km. Three-component strong motion accelerograms are integrated to obtain velocity, low-pass filtered at 4 s period and windowed to include the direct P- and S- wave arrivals. Theoretical Green's functions are calculated using the Direct Solution Method (DSM) [Cummins, etal, Geophys. Res. Lett., 1994] for each of 169, 4km x 4km, subfaults which lie on one of the two fault plates specified by the Harvard CMT solution. A unique 1-D model that gives an adequate representation of velocity structure for each station is obtained by path averaging the 3-D tomographic model. The S velocity model is generated from the P velocity model. For Vp larger than 4.5 km/s, We use the linear relationship Vs=0.18+0.52Vp obtained from laboratory measurements of local mafic rock samples. For slower velocities, probably associated with sedimentary rocks, we derived Vs=Vp/2.04 which best fits the strong-motion S-arrival times. The resulting source model indicates unilateral rupture along a fault that is elongated in the north-south direction. Inversion for the near vertical (strike 1° , dip 72° ) and horizontal (strike 183° , dip 18° ) fault planes reveal the same source directivity, however, the horizontal fault plane gives a slightly better fit to the data than the vertical one. We will also incorporate teleseismic P pP and sP waves into the waveform modeling to provide additional constraints on vertical source directivity.

Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence

PubMed Central

Convertito, Vincenzo; Catalli, Flaminia; Emolo, Antonio

2013-01-01

The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids. PMID:24177982

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.

[Quadriceps tendon insufficiency and rupture : Treatment options in total knee arthroplasty].

PubMed

Thiele, K; von Roth, P; Pfitzner, T; Preininger, B; Perka, C

2016-05-01

Quadriceps tendon injuries and insufficiencies in total knee arthroplasty are rare, but are followed by a devastating complication that left untreated leads to a complete loss of function of the knee. This review article summarizes the functional anatomy, risk factors, and the prevalence and diagnosis of quadriceps tendon injuries, in addition to the possible management options for partial and complete ruptures. The treatment options are adapted according to the extent of the loss of function (partial, complete) and the duration of the injury (acute vs chronic). Furthermore, the choice of treatment should take into account the quality and availability of primary tissue, the patient's general health, along with their likely functional requirements. Conservative treatment is often justified in partial ruptures with good results. Complete ruptures require surgical intervention and multiple operative techniques are described. Treatment options for acute ruptures include direct primary repair with autogenous or synthetic tissue augmentation. In the case of chronic insufficiency and a lack of soft-tissue surroundings, reconstruction with the aid of a muscle flap or allograft tissue can be considered. All surgical intervention techniques used so far have been fraught with complications and rarely lead to satisfactory results. A new surgical approach to the reconstruction and augmentation of the extensor mechanism consists of the use of a synthetic mesh. The technique is described here in detail.

Spontaneous rupture of the spleen due to infectious mononucleosis.

PubMed

Farley, D R; Zietlow, S P; Bannon, M P; Farnell, M B

1992-09-01

Spontaneous splenic rupture is an extremely rare but life-threatening complication of infectious mononucleosis in young adults. Although splenectomy remains effective treatment, reports of successful nonoperative management have challenged the time-honored approach of emergent laparotomy. On retrospective analysis of our institutional experience with 8,116 patients who had this disease during a 40-year period, we found 5 substantiated cases of atraumatic splenic rupture due to infectious mononucleosis. Four additional cases of suspected splenic rupture were noted. All nine patients were hospitalized and treated (seven underwent splenectomy and two were treated with supportive measures only), and they remain alive and well. In patients with infectious mononucleosis suspected of having rupture of the spleen, a rapid but thorough assessment and prompt implementation of appropriate management should minimize the associated morbidity and mortality. On the basis of review of the medical literature and careful scrutiny of our own experience, we advocate emergent splenectomy for spontaneous splenic rupture in patients with infectious mononucleosis.

The relevance and applicability of oocyst prevalence as a read-out for mosquito feeding assays

NASA Astrophysics Data System (ADS)

Stone, Will J. R.; Eldering, Maarten; van Gemert, Geert-Jan; Lanke, Kjerstin H. W.; Grignard, Lynn; van de Vegte-Bolmer, Marga G.; Siebelink-Stoter, Rianne; Graumans, Wouter; Roeffen, Will F. G.; Drakeley, Chris J.; Sauerwein, Robert W.; Bousema, Teun

2013-12-01

Mosquito feeding assays are important in evaluations of malaria transmission-reducing interventions. The proportion of mosquitoes with midgut oocysts is commonly used as an outcome measure, but in natural low intensity infections the effect of oocyst non-rupture on mosquito infectivity is unclear. By identifying ruptured as well as intact oocysts, we show that in low intensity P. falciparum infections i) 66.7-96.7% of infected mosquitoes experienced oocyst rupture between 11-21 days post-infection, ii) oocyst rupture led invariably to sporozoite release, iii) oocyst rupture led to salivary gland infections in 97.8% of mosquitoes, and iv) 1250 (IQR 313-2400) salivary gland sporozoites were found per ruptured oocyst. These data show that infectivity can be predicted with reasonable certainty from oocyst prevalence in low intensity infections. High throughput methods for detecting infection in whole mosquitoes showed that 18s PCR but not circumsporozoite ELISA gave a reliable approximation of mosquito infection rates on day 7 post-infection.

Fracture Mechanisms For SiC Fibers And SiC/SiC Composites Under Stress-Rupture Conditions at High Temperatures

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; Yun, Hee Mann; Hurst, Janet B.; Viterna, L. (Technical Monitor)

2002-01-01

The successful application of SiC/SiC ceramic matrix composites as high-temperature structural materials depends strongly on maximizing the fracture or rupture life of the load-bearing fiber and matrix constituents. Using high-temperature data measured under stress-rupture test conditions, this study examines in a mechanistic manner the effects of various intrinsic and extrinsic factors on the creep and fracture behavior of a variety of SiC fiber types. It is shown that although some fiber types fracture during a large primary creep stage, the fiber creep rate just prior to fracture plays a key role in determining fiber rupture time (Monkman-Grant theory). If it is assumed that SiC matrices rupture in a similar manner as fibers with the same microstructures, one can develop simple mechanistic models to analyze and optimize the stress-rupture behavior of SiC/SiC composites for applied stresses that are initially below matrix cracking.

Stress-rupture behavior of small diameter polycrystalline alumina fibers

NASA Technical Reports Server (NTRS)

Yun, Hee Mann; Goldsby, Jon C.; Dicarlo, James A.

1993-01-01

Continuous length polycrystalline alumina fibers are candidates as reinforcement in high temperature composite materials. Interest therefore exists in characterizing the thermomechanical behavior of these materials, obtaining possible insights into underlying mechanisms, and understanding fiber performance under long term use. Results are reported on the time-temperature dependent strength behavior of Nextel 610 and Fiber FP alumina fibers with grain sizes of 100 and 300 nm, respectively. Below 1000 C and 100 hours, Nextel 610 with the smaller grain size had a greater fast fracture and rupture strength than Fiber FP. The time exponents for stress-rupture of these fibers were found to decrease from approximately 13 at 900 C to below 3 near 1050 C, suggesting a transition from slow crack growth to creep rupture as the controlling fracture mechanism. For both fiber types, an effective activation energy of 690 kJ/mol was measured for rupture. This allowed stress-rupture predictions to be made for extended times at use temperatures below 1000 C.

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

Zhu, S.; Yang, M.; Song, X.L.

The Laves phase precipitation process was characterised by means of field emission scanning electron microscopy to demonstrate its effect on creep rupture strength of steels with a fully ferritic matrix. To eliminate the effects of carbide and carbonitride precipitations so that the creep rupture data can be analysed exclusively in relation to the Laves phase precipitation process, an alloy Fe–9Cr–3Co–3W (wt.%) without C and N additions was used for the study. Creep rupture strengths were measured and volume fraction and particle size of Laves phase precipitates in the ruptured specimens were analysed. It was found that the creep rupture strengthmore » started to collapse (or decrease more rapidly) long before the Laves phase precipitation reached equilibrium fraction. This was related to the onset of the coarsening of Laves phase particles, which precipitated only on grain boundaries and hence contributed little to precipitation strengthening. Creep deformation had no effect either on the precipitation kinetics or on the growth kinetics of Laves phase particles. - Highlights: • Laves phase precipitation at 650 °C was characterised for Fe–9Cr–3W–3Co alloy. • Laves phase precipitated predominantly on grain boundaries. • Creep deformation had no effect on Laves phase precipitation and growth kinetics. • Creep strength started to collapse long before Laves phase precipitation is ended. • Collapse of creep strength was attributed to the coarsening of Laves phase particles.« less

Single Event Effects (SEE) for Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)

NASA Technical Reports Server (NTRS)

Lauenstein, Jean-Marie

2011-01-01

Single-event gate rupture (SEGR) continues to be a key failure mode in power MOSFETs. (1) SEGR is complex, making rate prediction difficult SEGR mechanism has two main components: (1) Oxide damage-- Reduces field required for rupture (2) Epilayer response -- Creates transient high field across the oxide.

Rupture complexity and the supershear transition on rough faults

NASA Astrophysics Data System (ADS)

Bruhat, Lucile; Fang, Zijun; Dunham, Eric M.

2016-01-01

Field investigations suggest that supershear earthquakes occur on geometrically simple, smooth fault segments. In contrast, dynamic rupture simulations show how heterogeneity of stress, strength, and fault geometry can trigger supershear transitions, as well as other complex rupture styles. Here we examine the Fang and Dunham (2013) ensemble of 2-D plane strain dynamic ruptures on fractally rough faults subject to strongly rate weakening friction laws to document the effect of fault roughness and prestress on rupture behavior. Roughness gives rise to extremely diverse rupture styles, such as rupture arrests, secondary slip pulses that rerupture previously slipped fault sections, and supershear transitions. Even when the prestress is below the Burridge-Andrews threshold for supershear on planar faults with uniform stress and strength conditions, supershear transitions are observed. A statistical analysis of the rupture velocity distribution reveals that supershear transients become increasingly likely at higher stress levels and on rougher faults. We examine individual ruptures and identify recurrent patterns for the supershear transition. While some transitions occur on fault segments that are favorably oriented in the background stress field, other transitions happen at the initiation of or after propagation through an unfavorable bend. We conclude that supershear transients are indeed favored by geometric complexity. In contrast, sustained supershear propagation is most common on segments that are locally smoother than average. Because rupture style is so sensitive to both background stress and small-scale details of the fault geometry, it seems unlikely that field maps of fault traces will provide reliable deterministic predictions of supershear propagation on specific fault segments.

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.

Development of exothermically cast single-crystal Mar-M 247 and derivative alloys

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Hoppin, G. S., III; Phipps, C. M.; Harris, K.; Schwer, R. E.

1980-01-01

A low-cost, exothermic directional-solidification (DS) process was developed to produce single-crystal (SC) Mar-M 247 high-pressure turbine blades. Stress-rupture data indicated that SC Mar-M 247 provides only marginal improvements in longitudinal strength relative to the columnar grained DS material. Removal of grain boundary strengthening elements (B, C, Zr, Hf) from the Mar-M 247 composition (which are also melting point depressants) permitted the alloy to be solutioned at significantly higher temperatures. An order of magnitude improvement in rupture life relative to SC Mar-M 247 was observed for several derivative alloys at 103.5 MPa (15 KSI) and 1093 C. Rupture lives of the modified SC alloys were significantly affected by both alloy purity and heat treatment. Critical aspects of vacuum induction refining, exothermic casting technology, alloy development and heat treatment, which contributed to this new class of turbine blades, are reviewed

Sudden Death From Ruptured Intracranial Vascular Malformations During Mechanical Asphyxia: A Domestic Violence Case Report.

PubMed

Wu, Xue-Mei; Zhang, Xu-Dong; Yun, Li-Bing; Liu, Min; Yi, Xu-Fu

2017-03-01

Smothering and manual strangulation are not uncommon in domestic violence against women; however, no report on the combination of mechanical asphyxia and intracranial vascular malformations has been previously published. We report a middle-aged woman who was smothered and manually strangled by her husband and subsequently died from subarachnoid hemorrhage due to ruptured intracranial vascular malformations, rather than direct mechanical asphyxiation. Smothering and manual strangulation are considered provocative conditions for rupture and contributory causes of death. In this case study, we underline the importance of meticulous autopsy in cases of mechanical asphyxia and intracranial hemorrhage. Exclusion of underlying diseases that may have caused or contributed to death is also required, despite serious asphyxiation signs and neck injuries. Postmortem angiography is a valuable complement to autopsy to detect vascular pathology, with good prospects for further development in China.

[Aortic stenosis and mitral regurgitation complicated by hemolytic anemia and positive Direct Coombs test: a case report].

PubMed

Tamura, Shinjiro; Kitaoka, Hiroaki; Yamasaki, Naohito; Okawa, Makoto; Kubo, Toru; Matsumura, Yoshihisa; Furuno, Takashi; Takata, Jun; Nishinaga, Masanori; Sasaguri, Shiro; Doi, Yoshinori

2005-09-01

A 83-year-old man was admitted because of heart failure due to severe aortic stenosis and mitral regurgitation secondary to chordal rupture of the anterior leaflet. Mild anemia and elevated serum lactate dehydrogenase were present with reticulocytosis and haptoglobinemia. Direct Coombs test was positive. Coexistence of autoimmune hemolytic anemia was identified, but the main cause of his hemolysis was thought to be mechanical hemolysis due to stenotic valve and/or ruptured chordae because of the presence of red cell fragmentation. The patient successfully underwent double valve replacement. Improvement of anemia was coupled with reduction of the serum lactate dehydrogenase level. Valvular shear stress on the red cells and reduction of red cell deformability secondary to autoimmune hemolytic anemia were thought to be responsible for his hemolysis.

Numerical Models of Stopping Ruptures on a Bimaterial Interface

NASA Astrophysics Data System (ADS)

Rubin, A. M.; Ampuero, J.

2003-12-01

Using a cross-correlation earthquake relocation technique, Rubin and Gillard (2000) and Rubin (2002) found that the nearest aftershocks of microearthquakes on the San Andreas fault were much more likely (by a ratio of nearly 3:1) to occur to the NW of the mainshock than to the SE. They attributed this asymmetry to the material contrast across the fault and the resulting dynamical reduction in normal stress near the rupture front propagating to the SE (the front moving in the direction of slip of the more compliant medium). Specifically, it was hypothesized that regions of the fault far enough from failure to resist this extra dynamical "kick" would be that much farther from failure once those dynamical stresses decayed. However, analytical (steady-state) models of propagating slip on a bimaterial interface (Weertman, 1980) show that, as with the static stress field, normal stress changes occur only behind the rupture front. The proposed explanation works most simply if the region ahead of the SE rupture front experiences a transient stress favorable for slip. In principal this stress transient could be associated with either rupture growth or arrest. To investigate this further, we ran 2-D numerical models of slip on a bimaterial interface with slip-weakening friction, using the code of Cochard and Rice (2000). The ruptures spontaneously accelerate to the generalized Rayleigh wave speed of the medium, when such exists. During this growth phase, large tensile stresses are indeed restricted to regions of large slip velocity behind the SE-propagating rupture front. Ahead of the rupture front the normal stresses are smaller and compressive. If the rupture front is stopped abruptly, the short-wavelength tensile stress pulse continues to propagate at roughly the same velocity. The above comments also apply in an anti-symmetric sense to the NW rupture front, although there the slip speeds and normal stress changes are lower. If the rupture is stopped by a more gradual reduction in the loading stress, the moving tensile pulse can spawn a decaying slip pulse at the SE front but not the NW. If this slip pulse marks the furthest extent of slip, the resulting static stress field is quite asymmetric even for a symmetric initial stress, lying on the failure envelope at the NW end of the rupture but well below it at the SE end. These results are at least permissive of the explanation proposed by Rubin and Gillard. For weaker slip pulses (due to any of a number of factors contributing to smaller maximum slip speeds), the furthest extent of slip near the SE rupture front can be driven by the stopping phase arriving from the NW end of the crack. Under such conditions the final stress field is more symmetric. We will be running models using heterogeneous stress fields to explore these questions further, and hope to use rate-and-state friction to investigate the observed temporal decay of the aftershock asymmetry.

Effect of position, time in the season, and playing surface on Achilles tendon ruptures in NFL games: a 2009-10 to 2016-17 review.

PubMed

Krill, Michael K; Borchers, James R; Hoffman, Joshua T; Krill, Matthew L; Hewett, Timothy E

2017-09-01

Achilles tendon (AT) ruptures are a potentially career-altering and ending injury. Achilles tendon ruptures have a below average return-to-play rate compared to other common orthopaedic procedures for National Football League (NFL) players. The objective of this study was to monitor the incidence and injury rates (IR) of AT ruptures that occurred during the regular season in order to evaluate the influence of player position, time of injury, and playing surface on rupture rates. A thorough online review was completed to identify published injury reports and public information regarding AT ruptures sustained during regular season and post-season games in the National Football League (NFL) during the 2009-10 to 2016-17 seasons. Team schedules, player position details and stadium information was used to determine period of the season of injury and playing surface. IRs were calculated per 100 team games (TG). Injury rate ratios (IRR) were utilized to compare IRs. During eight monitored seasons, there were 44 AT ruptures in NFL games. A majority of AT ruptures were sustained in the first eight games of the regular season (n = 32, 72.7%). There was a significant rate difference for the first and second four-game segments of the regular season compared to the last two four-game segments of the regular season. Defensive players suffered a majority of AT ruptures (n = 32, 72.7%). The IR on grass was 1.00 per 100 TG compared to 1.08 per 100 TG on artificial turf (IRR: 0.93, p = .80). A significant increase in AT ruptures occurred in the first and second four game segments of the regular season compared to the last two-four game segments of the regular season. Defensive players suffered a majority of AT ruptures compared to offensive or specialist players. There was no difference between AT rupture rates and playing surface in games.

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.

[Neurologic complications of subarachnoid hemorrhage due to intracranial aneurysm rupture].

PubMed

Rama-Maceiras, P; Fàbregas Julià, N; Ingelmo Ingelmo, I; Hernández-Palazón, J

2010-12-01

The high rates of morbidity and mortality after subarachnoid hemorrhage due to spontaneous rupture of an intracranial aneurysm are mainly the result of neurologic complications. Sixty years after cerebral vasospasm was first described, this problem remains unsolved in spite of its highly adverse effect on prognosis after aneurysmatic rupture. Treatment is somewhat empirical, given that uncertainties remain in our understanding of the pathophysiology of this vascular complication, which involves structural and biochemical changes in the endothelium and smooth muscle of vessels. Vasospasm that is refractory to treatment leads to cerebral infarction. Prophylaxis, early diagnosis, and adequate treatment of neurologic complications are key elements in the management of vasospasm if neurologic damage, lengthy hospital stays, and increased use of health care resources are to be avoided. New approaches to early treatment of cerebral lesions and cortical ischemia in cases of subarachnoid hemorrhage due to aneurysm rupture should lead to more effective, specific management.

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.

Spontaneous Hemothorax in Neurofibromatosis Treated with Percutaneous Embolization

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

Arai, Kazunori; Sanada, Junichiro; Kurozumi, Akiko

We evaluated the effectiveness of transcatheter arterial coil embolization therapy for the treatment of spontaneous hemothorax followed by aneurysm rupture in neurofibromatosis patients. Three patients were treated for massive hemothorax caused by arterial lesions associated with neurofibromatosis. Bleeding episodes were secondary to ascending cervical artery aneurysm and dissection of vertebral artery in 1 patient, and intercostal artery aneurysm with or without arteriovenous fistula in 2 patients. Patients were treated by transarterial coil embolization combined with chest drainage. In 1 patient, the ruptured ascending cervical artery aneurysm was well embolized but, shortly after the embolization, fatal hemorrhage induced by dissection ofmore » the vertebral artery occurred and the patient died. In the other 2 patients, the ruptured intercostal artery aneurysm was well embolized and they were successfully treated and discharged. Transcatheter arterial coil embolization therapy is an effective method for the treatment of spontaneous hemothorax followed by aneurysm rupture in neurofibromatosis patients.« less

Amplification of tsunami heights by delayed rupture of great earthquakes along the Nankai trough

NASA Astrophysics Data System (ADS)

Imai, K.; Satake, K.; Furumura, T.

2010-04-01

We investigated the effect of delayed rupture of great earthquakes along the Nankai trough on tsunami heights on the Japanese coast. As the tsunami source, we used a model of the 1707 Hoei earthquake, which consists of four segments: Tokai, Tonankai, and two Nankai segments. We first searched for the worst case, in terms of coastal tsunami heights, of rupture delay time on each segment, on the basis of superposition principle for the linear long wave theory. When the rupture starts on the Tonankai segment, followed by rupture on the Tokai segment 21 min later, as well as the eastern and western Nankai segments 15 and 28 min later, respectively, the average coastal tsunami height becomes the largest. To quantify the tsunami amplification, we compared the coastal tsunami heights from the delayed rupture with those from the simultaneous rupture model. Along the coasts of the sea of Hyu'uga and in the Bungo Channel, the tsunami heights become significantly amplified (>1.4 times larger) relative to the simultaneous rupture. Along the coasts of Tosa Bay and in the Kii Channel, the tsunami heights become amplified about 1.2 times. Along the coasts of the sea of Kumano and Ise Bay, and the western Enshu coast, the tsunami heights become slightly smaller for the delayed rupture. Along the eastern Enshu coast, the coast of Suruga Bay, and the west coast of Sagami Bay, the tsunami heights become amplified about 1.1 times.

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.

Surgical Treatment Versus Conservative Management for Acute Achilles Tendon Rupture: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

PubMed

Deng, Senlin; Sun, Zhengyu; Zhang, Chenghao; Chen, Gang; Li, Jian

Acute Achilles tendon ruptures can be treated with surgical and nonsurgical treatment. However, the optimal intervention for acute Achilles tendon rupture remains controversial. The aim of the present study was to compare the clinical outcomes of surgical treatment versus conservative management for acute Achilles tendon rupture. Eight randomized controlled studies involving 762 patients were included in the meta-analysis. In general, re-rupture occurred in 14 of 381 surgically treated patients (3.7%) and 37 of 377 nonsurgically treated patients (9.8%). Pooled results showed that the total re-rupture rate was significantly lower in surgical group than that in the nonsurgical group (risk ratio 0.38, 95% confidence interval 0.21 to 0.68; p = .001). No significant differences were found between the 2 treatment groups in the incidence of deep venous thrombosis, the number who returned to sport, ankle range of motion (dorsiflexion, plantarflexion), Achilles tendon total rupture score, or physical activity scale. Surgical treatment can effectively reduce the re-rupture rate and might be a better choice for the treatment of acute Achilles tendon rupture. Multicenter, double-blind randomized controlled trials with stratification and long-term follow-up are needed to obtain a higher level of evidence and to guide clinical practice, especially in the comparison and selection of different treatments. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

A Three Year Clinicopathological Study of Cases of Rupture Uterus

PubMed Central

Rathod, Setu; Swain, Sujata

2015-01-01

Introduction Rupture uterus is a life threatening obstetric complication with serious maternal and fetal side-effects. We report a 3 year (2010-2013) retrospective clinical study of pregnancy with rupture uterus cases attending a tertiary care hospital. Aim The aim of the study was to evaluate the incidence of rupture uterus, incidence as per age, parity, clinical presentations, risk factors, complications and management. Materials and Methods Retrospective data of 74 cases of rupture uterus in SCB Medical college, Cuttack was collected from case records of 26,547 deliveries during a 3 year span (2010-2013). Parameters like cause of rupture, type, site of rupture and outcome were recorded. The collected data was analysed by SPSS software v19. Results Out of 26,547 deliveries during the three year period, there were 74 cases of rupture uterus with an incidence of rupture 1 in 359 (0.28%). The mean age of rupture uterus was 27.4 years. 95.8% were multigravida and majority were referred cases from low socioeconomic status. Only 40.5% had the required minimum of four antenatal visits as recommended by WHO (World Health Organisation). A total of 48.6% of cases with rupture uterus had history of previous Caesarean section. Prolonged labour was present in 75.6% of the cases. Only 12.2% of the cases had history of oxytocin use whereas 9.5% had undergone an operative vaginal delivery. Obstructed labour was the cause in 24.3% of cases, 85.1% had complete rupture. Majority had a rupture in the anterior wall (69%) and 81.1% had rupture in lower segment of uterus. Only 17.6% had broad ligament haematoma, 10.8% colporrhexis and 6.8% had associated bladder injury. Repair was possible in only 39.2% of cases, whereas majority landed up in hysterectomy. Internal iliac ligation was done in 2.7% of cases. Perinatal mortality was 90.5% whereas maternal death was seen in 13.5% cases. One patient developed VVF (vesicovaginal fistula). Duration of hospital stay was upto 14 days in 81.1% cases. Conclusion Education and proper care especially of high risk patients like previous caesarean by competent personnal, proper use of oxytocin and early referral may help to reduce the incidence of “rupture uterus”. PMID:26673858

Distal biceps tendon history, updates, and controversies: from the closed American Shoulder and Elbow Surgeons meeting-2015.

PubMed

Schmidt, Christopher C; Savoie, Felix H; Steinmann, Scott P; Hausman, Michael; Voloshin, Ilya; Morrey, Bernard F; Sotereanos, Dean G; Bero, Emily H; Brown, Brandon T

2016-10-01

Understanding of the distal biceps anatomy, mechanics, and biology during the last 75 years has greatly improved the physician's ability to advise and to treat patients with ruptured distal tendons. The goal of this paper is to review the past and current advances on complete distal biceps ruptures as well as controversies and future directions that were discussed and debated during the closed American Shoulder and Elbow Surgeons meeting in 2015. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Pulse-like partial ruptures and high-frequency radiation at creeping-locked transition during megathrust earthquakes

NASA Astrophysics Data System (ADS)

Michel, Sylvain; Avouac, Jean-Philippe; Lapusta, Nadia; Jiang, Junle

2017-08-01

Megathrust earthquakes tend to be confined to fault areas locked in the interseismic period and often rupture them only partially. For example, during the 2015 M7.8 Gorkha earthquake, Nepal, a slip pulse propagating along strike unzipped the bottom edge of the locked portion of the Main Himalayan Thrust (MHT). The lower edge of the rupture produced dominant high-frequency (>1 Hz) radiation of seismic waves. We show that similar partial ruptures occur spontaneously in a simple dynamic model of earthquake sequences. The fault is governed by standard laboratory-based rate-and-state friction with the aging law and contains one homogenous velocity-weakening (VW) region embedded in a velocity-strengthening (VS) area. Our simulations incorporate inertial wave-mediated effects during seismic ruptures (they are thus fully dynamic) and account for all phases of the seismic cycle in a self-consistent way. Earthquakes nucleate at the edge of the VW area and partial ruptures tend to stay confined within this zone of higher prestress, producing pulse-like ruptures that propagate along strike. The amplitude of the high-frequency sources is enhanced in the zone of higher, heterogeneous stress at the edge of the VW area.

Pulse-Like Partial Ruptures and High-Frequency Radiation at Creeping-Locked Transition during Megathrust Earthquakes

NASA Astrophysics Data System (ADS)

Michel, S. G. R. M.; Avouac, J. P.; Lapusta, N.; Jiang, J.

2017-12-01

Megathrust earthquakes tend to be confined to fault areas locked in the interseismic period and often rupture them only partially. For example, during the 2015 M7.8 Gorkha earthquake, Nepal, a slip pulse propagating along strike unzipped the bottom edge of the locked portion of the Main Himalayan Thrust (MHT). The lower edge of the rupture produced dominant high-frequency (>1 Hz) radiation of seismic waves. We show that similar partial ruptures occur spontaneously in a simple dynamic model of earthquake sequences. The fault is governed by standard laboratory-based rate-and-state friction with the ageing law and contains one homogenous velocity-weakening (VW) region embedded in a velocity-strengthening (VS) area. Our simulations incorporate inertial wave-mediated effects during seismic ruptures (they are thus fully dynamic) and account for all phases of the seismic cycle in a self-consistent way. Earthquakes nucleate at the edge of the VW area and partial ruptures tend to stay confined within this zone of higher prestress, producing pulse-like ruptures that propagate along strike. The amplitude of the high-frequency sources is enhanced in the zone of higher, heterogeneous stress at the edge of the VW area.

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.

Effects on proprioception by Kinesio taping of the knee after anterior cruciate ligament rupture.

PubMed

Bischoff, Lars; Babisch, Christian; Babisch, Jürgen; Layher, Frank; Sander, Klaus; Matziolis, Georg; Pietsch, Stefan; Röhner, Eric

2018-03-10

The use of Kinesio tape (KT) to improve proprioception is a matter of considerable debate. In comparison, the rupture of the anterior cruciate ligament is a sufficiently well-investigated injury with a proven compromise of proprioception. The objective of the present study was to assess a supportive effect on proprioception after KT application, taking the anterior cruciate ligament (ACL) rupture as an example. Forty-eight patients who had suffered an ACL rupture, confirmed clinically and by magnetic resonance imaging, and who were treated conservatively or were awaiting surgery were included in this study. In all patients, a gait analysis was performed on the affected leg before and after KT application. In addition, the IKDC score, the Lysholm score, stability using the Rolimeter, and the angle reproduction test were determined. Thirty-nine men and nine women who had had an ACL rupture for at least 3 weeks were included in the study. Significant improvements were achieved on the affected knee joint for the gait analysis parameters touchdown and unrolling, cadence, stability and stance phase as well as an extension of the hip joint. The Lysholm score improved from 79.3 to 85.8 (p < 0.001) and the IKDC score from 60.2 to 71.3 points (p < 0.001). Significant improvements were achieved in the Rolimeter and angle reproduction test. The use of KT has a positive effect on proprioception in patients with an anterior cruciate ligament rupture. Therefore, the application may improve gait pattern as well as the subjective function of the affected knee joint.

Five centuries of tsunamis and land-level changes in the overlapping rupture area of the 1960 and 2010 Chilean earthquakes

USGS Publications Warehouse

Ely, Lisa L.; Cisternas, Marco; Wesson, Robert L.; Dura, Tina

2014-01-01

A combination of geological and historical records from south-central Chile provides a means to address general questions about the stability of megathrust rupture patches and the range of variation expected among earthquakes and tsunamis along a particular stretch of a subduction zone. The Tirúa River estuary (38.3°S) records four large tsunamis and coseismic land-level changes over the past 450 years within the overlapping rupture zones of the great subduction-zone earthquakes of A.D. 1960 (Mw9.5) and 2010 (Mw 8.8). Sand layers 2 km up the Tirúa River represent the 2010 and 1960 tsunamis and two historical tsunamis, most likely in A.D. 1751 and 1575. Differing land-level changes during these earthquakes likely denote differences in the spatial distribution of slip on the megathrust in both the strike and dip directions within the overlapping rupture zone, with the uplift at Tirúa in 1751 and 2010 probably caused by slip extending farther landward and to greater depth than in 1575 and 1960, which showed subsidence or little change.

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.

Cellular interface morphologies in directional solidification. II - The effect of grain boundaries

NASA Technical Reports Server (NTRS)

Ungar, Lyle H.; Brown, Robert A.

1984-01-01

A singular perturbation analysis valid for small grain-boundary slopes is used with the one-sided model for solidification to show that grain boundaries introduce imperfections into the symmetry of the developing cellular interfaces which rupture the junction between the family of planar shapes and the bifurcating cellular families. Undulating interfaces are shown to develop first near grain boundaries, and to evolve with decreasing temperature gradient either by a smooth transition from the almost planar family or by a sudden jump to moderate-amplitude cellular forms, depending on the growth rate.

A surface-wave investigation of the rupture mechanism of the Gobi-Altai (4 December 1957) earthquake

NASA Technical Reports Server (NTRS)

Okal, E. A.

1975-01-01

Long period records of multiple Love waves from the 1957 earthquake in Mongolia at Pasadena are analyzed and compared to synthetic seismograms, generated by the method of Kanamori. A fit in the time domain shows that the records are not consistent with the previous solution, achieved through a frequency domain analysis of directivity. The solution asks for a shorter rupture of 270 km at a velocity of 3.5 km/s. The focal parameters are constrained by updating all the reported first motion and are found to be: Strike = 103 deg, Dip = 53 deg, Slip = 32 deg. A seismic moment of 1.8 10 to the 28th power dynes-cm is obtained. These figures are also consistent with a time domain analysis of Love waves at Palisades and Strasbourg, and of Rayleigh waves at Pasadena, with a directivity study of Love waves at Pasadena, and with static deformation and isoseismal data. A discussion is given of the relation between moment, magnitude and rupture area, and a comparison is made with other events in the same region: It is concluded that this earthquake does not exhibit an intra-plate behavior, but rather compares better with inter-plate events, such as the great Assam earthquake.

Origin, growth, and rupture of saccular aneurysms: a review.

PubMed

Sekhar, L N; Heros, R C

1981-02-01

Pathological and hemodynamic concepts regarding the origin, growth, and rupture of intracranial saccular aneurysms are reviewed. Aneurysms form as a result of an interplay between hemodynamic factors, such as axial stream impingement and the water hammer effect, and structural weaknesses at apices of arterial bifurcations, such as congenital and acquired medial defects, funnel-shaped dilatations, and areas of thinning. Hypertension and time aid the formation of aneurysms. Unknown factors in women and in some families also play a role. Enlargement of aneurysms results from an interplay between mechanical factors, such as self-excitation and resonance, that produce structural fatigue and pathological processes of repair of the aneurysmal wall. Rupture of aneurysms is caused by the same hemodynamic factors that effect growth and is also influenced by extramural pressure. Pathologically, a major rupture may be preceded by fibrinous and leukocytic infiltration of the wall, bleb formation, and a minor hemorrhage. Such minor leaks can be followed by healing and growth. Aneurysms that escape major hemorrhage or heal successfully after a hemorrhage can grow to giant proportions, but remain susceptible to rupture despite their size, unless they become completely thrombosed. Intramural thrombosis may be stimulated by minor leaks and is dependent upon the physical characteristics of aneurysms. Experimental, angiographic, and clinical studies that pertain to the origin, growth, and rupture of aneurysms are also reviewed.

Cumulative co-seismic fault damage and feedbacks on earthquake rupture

NASA Astrophysics Data System (ADS)

Mitchell, T. M.; Aben, F. M.; Ostermeijer, G.; Rockwell, T. K.; Doan, M. L.

2017-12-01

The importance of the damage zone in the faulting and earthquake process is widely recognized, but our understanding of how damage zones are created, what their properties are, and how they feed back into the seismic cycle, is remarkably poorly known. Firstly, damaged rocks have reduced elastic moduli, cohesion and yield strength, which can cause attenuation and potentially non-linear wave propagation effects during ruptures. Secondly, damaged fault rocks are generally more permeable than intact rocks, and hence play a key role in the migration of fluids in and around fault zones over the seismic cycle. Finally, the dynamic generation of damage as the earthquake propagates can itself influence the dynamics of rupture propagation, by increasing the amount of energy dissipation, decreasing the rupture velocity, modifying the size of the earthquake, changing the efficiency of weakening mechanisms such as thermal pressurisation of pore fluids, and even generating seismic waves itself . All of these effects imply that a feedback exists between the damage imparted immediately after rupture propagation, at the early stages of fault slip, and the effects of that damage on subsequent ruptures dynamics. In recent years, much debate has been sparked by the identification of so-called `pulverized rocks' described on various crustal-scale faults, a type of intensely damaged fault rock which has undergone minimal shear strain, and the occurrence of which has been linked to damage induced by transient high strain-rate stress perturbations during earthquake rupture. Damage induced by such transient stresses, whether compressional or tensional, likely constitute heterogeneous modulations of the remote stresses that will impart significant changes on the strength, elastic and fluid flow properties of a fault zone immediately after rupture propagation, at the early stage of fault slip. In this contribution, we will demonstrate laboratory and field examples of two dynamic mechanisms that have been proposed for the generation of pulverized rocks; (i) compressive loading by high-frequency stress pulses due to the radiation of seismic waves and (ii) explosive dilation in tension in rocks containing pressurized pore fluids.

Theoretical Constraints on Properties of Dynamic Ruptures Implied by Pulverized Fault Zone Rocks

NASA Astrophysics Data System (ADS)

Xu, S.; Ben-Zion, Y.

2016-12-01

Prominent belts of Pulverized Fault Zone Rocks (PFZR) have been observed adjacent to several major strike-slip faults that separate different crustal blocks. They consist of 100-200m wide zones of highly damaged rock products, primarily of crystalline origin, that were mechanically shattered to sub-micron scale while preserving most of their original fabric with little evidence of shear. PFZR are strongly asymmetric with respect to the fault trace, existing primarily on the side with higher seismic velocity at depth, and their fabric suggests volumetric deformation with tensile cracks in all directions (e.g., Dor et al., 2006; Rockwell et al., 2009; Mitchell et al., 2011). Generating with split Hopkinson pressure bar in intact cm-scale sample microstructures similar to those observed in PFZR requires strain-rates higher than 150/s (e.g., Doan and Gary, 2009; Yuan et al., 2011). Using samples with preexisting damage reduces the strain-rate required for pulverization by 50% (Doan and d'Hour, 2012). These laboratory observations support earlier suggestions that PFZR are produced by dynamic stress fields at the tip of earthquake ruptures (e.g., Ben-Zion and Shi, 2005; Reches and Dewers, 2005). To clarify the conditions associated with generation of PFZR, we discuss theoretical results based on Linear Elastic Fracture Mechanics and simulations of Mode-II dynamic ruptures on frictional faults (Xu and Ben-Zion, 2016). We consider subshear and supershear ruptures along faults between similar and dissimilar solids. The results indicate that strain-rates higher than 150/s can be generated at distance of about 100m from the fault by either subshear ruptures on a bimaterial interface or supershear ruptures between similar and dissimilar solids. The dynamic fields of subshear bimaterial ruptures are expected to produce off-fault damage primarily on the stiff side of the fault, with tensile cracks that have no preferred orientation, in agreement with observations. In contrast, the supershear ruptures are likely to produce off-fault damage on both sides of the fault with preferred tensile crack orientations. Additional laboratory tests with multi-axial tension and larger samples with preexisting damage can clarify further the dynamic conditions implied by observed PFZR.

Heterogeneous Rupture in the Great Cascadia Earthquake of 1700 Inferred from Coastal Subsidence Estimates

NASA Astrophysics Data System (ADS)

Wang, P.; Wang, K.; Hawkes, A.; Horton, B. P.; Engelhart, S. E.; Nelson, A. R.; Witter, R. C.

2011-12-01

Abrupt coastal subsidence induced by the great AD 1700 Cascadia earthquake has been estimated from paleoseismic evidence of buried soils and overlying mud and associated tsunamis deposits. These records have been modeled using a rather uniform rupture model, a mirror image of the uniform interseismic fault locking based on modern GPS observations. However, as seen in other megathrust earthquakes such as at Sumatra, Chile, and Alaska, the rupture must have had multiple patches of concentrated slip. Variable moment release is also seen in the 2011 Tohoku-Oki earthquake in Japan, although there is only one patch. The use of a uniform rupture scenario for Cascadia is due mainly to the poor resolving power of the previous paleoseismic data. In this work, we invoke recently obtained more precise data from detailed microfossil studies to better constrain the slip distribution. Our 3-D elastic dislocation model allows the fault slip to vary along strike. Along any profile in the dip direction, we assume a bell-shaped slip distribution with the peak value scaling with local rupture width, consistent with rupture mechanics. We found that the coseismic slip is large in central Cascadia, and areas of high moment release are separated by areas of low moment release. The amount of slip in northern and southern Cascadia is poorly constrained. Although data uncertainties are large, the coastal variable subsidence can be explained with multiple slip patches. For example, there is an area near Alsea Bay, Oregon (about 44.5°N) that, in accordance with the minimum coseismic subsidence estimated by the microfossil data, had very little slip in the 1700 event. This area approximately coincides with a segment boundary previously defined on the basis of gravity anomalies. There is also reported evidence for the presence of a subducting seamount in this area, and the seamount might be responsible for impeding rupture during large earthquakes. The nature of this rupture barrier and whether it is a persistent feature are important topics of future research. Our results indicate that there is not always a one-to-one correlation between areas of more complete interseismic locking and larger coseismic slip.

PIP breast implants: rupture rate and correlation with breast cancer

PubMed Central

MOSCHETTA, M.; TELEGRAFO, M.; CORNACCHIA, I.; VINCENTI, L.; RANIERI, V.; CIRILLI, A.; RELLA, L.; IANORA, A.A. STABILE; ANGELELLI, G.

2014-01-01

Aim To evaluate the incidence of Poly Implant Prosthése (PIP) rupture as assessed by magnetic resonance imaging (MRI), the prevalence of the detected signs and the potential correlation with breast carcinoma. Patients and methods 67 patients with silicone breast implants and clinical indications for breast MRI were evaluated for a total of 125 implants: 40 (32%) PIP in 21 patients and 85 non-PIP in 46 patients (68%), the latest considered as control group. A 1.5-T MR imaging device was used in order to assess implant integrity with dedicated sequences and in 6 cases a dynamic study was performed for characterizing breast lesions. Two radiologists with more than 5 years’ experience in the field of MRI evaluated in consensus all MR images searching for the presence of clear signs of intra or extra-capsular implant rupture. Results 20/40 (50%) PIP implants presented signs of intra-capsular rupture: linguine sign in 20 cases (100%), tear-drop sign in 6 (30%). In 12/20 cases (60%), MRI signs of extra-capsular rupture were detected. In the control group, an intra-capsular rupture was diagnosed in 12/85 cases (14%) associated with extra-capsular one in 5/12 cases (42%). Among the six cases with suspected breast lesions, in 2/21 patients with PIP implants (10%) a breast carcinoma was diagnosed (mucinous carcinoma, n=1; invasive ductal carcinoma, n=1). In 4/46 patients (9%) with non-PIP implants, an invasive ductal carcinoma was diagnosed. Conclusion The rupture rate of PIP breast implants is significantly higher than non-PIP (50% vs 14%). MRI represents the most accurate imaging tool for evaluating breast prostheses and the linguine sign is the most common MRI sign to be searched. The incidence of breast carcinoma does not significantly differ between the PIP and non-PIP implants and a direct correlation with breast cancer can not been demonstrated. PMID:25644728

PIP breast implants: rupture rate and correlation with breast cancer.

PubMed

Moschetta, M; Telegrafo, M; Cornacchia, I; Vincenti, L; Ranieri, V; Cirili, A; Rella, L; Stabile Ianora, A A; Angelelli, G

2014-01-01

To evaluate the incidence of Poly Implant Prosthése (PIP) rupture as assessed by magnetic resonance imaging (MRI), the prevalence of the detected signs and the potential correlation with breast carcinoma. 67 patients with silicone breast implants and clinical indications for breast MRI were evaluated for a total of 125 implants: 40 (32%) PIP in 21 patients and 85 non-PIP in 46 patients (68%), the latest considered as control group. A 1.5-T MR imaging device was used in order to assess implant integrity with dedicated sequences and in 6 cases a dynamic study was performed for characterizing breast lesions. Two radiologists with more than 5 years' experience in the field of MRI evaluated in consensus all MR images searching for the presence of clear signs of intra or extra-capsular implant rupture. 20/40 (50%) PIP implants presented signs of intra-capsular rupture: linguine sign in 20 cases (100%), tear-drop sign in 6 (30%). In 12/20 cases (60%), MRI signs of extra-capsular rupture were detected. In the control group, an intra-capsular rupture was diagnosed in 12/85 cases (14%) associated with extra-capsular one in 5/12 cases (42%). Among the six cases with suspected breast lesions, in 2/21 patients with PIP implants (10%) a breast carcinoma was diagnosed (mucinous carcinoma, n=1; invasive ductal carcinoma, n=1). In 4/46 patients (9%) with non-PIP implants, an invasive ductal carcinoma was diagnosed. The rupture rate of PIP breast implants is significantly higher than non-PIP (50% vs 14%). MRI represents the most accurate imaging tool for evaluating breast prostheses and the linguine sign is the most common MRI sign to be searched. The incidence of breast carcinoma does not significantly differ between the PIP and non-PIP implants and a direct correlation with breast cancer can not been demonstrated.

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.

Off-fault plasticity in three-dimensional dynamic rupture simulations using a modal Discontinuous Galerkin method on unstructured meshes: Implementation, verification, and application

NASA Astrophysics Data System (ADS)

Wollherr, Stephanie; Gabriel, Alice-Agnes; Uphoff, Carsten

2018-05-01

The dynamics and potential size of earthquakes depend crucially on rupture transfers between adjacent fault segments. To accurately describe earthquake source dynamics, numerical models can account for realistic fault geometries and rheologies such as nonlinear inelastic processes off the slip interface. We present implementation, verification, and application of off-fault Drucker-Prager plasticity in the open source software SeisSol (www.seissol.org). SeisSol is based on an arbitrary high-order derivative modal Discontinuous Galerkin (ADER-DG) method using unstructured, tetrahedral meshes specifically suited for complex geometries. Two implementation approaches are detailed, modelling plastic failure either employing sub-elemental quadrature points or switching to nodal basis coefficients. At fine fault discretizations the nodal basis approach is up to 6 times more efficient in terms of computational costs while yielding comparable accuracy. Both methods are verified in community benchmark problems and by three dimensional numerical h- and p-refinement studies with heterogeneous initial stresses. We observe no spectral convergence for on-fault quantities with respect to a given reference solution, but rather discuss a limitation to low-order convergence for heterogeneous 3D dynamic rupture problems. For simulations including plasticity, a high fault resolution may be less crucial than commonly assumed, due to the regularization of peak slip rate and an increase of the minimum cohesive zone width. In large-scale dynamic rupture simulations based on the 1992 Landers earthquake, we observe high rupture complexity including reverse slip, direct branching, and dynamic triggering. The spatio-temporal distribution of rupture transfers are altered distinctively by plastic energy absorption, correlated with locations of geometrical fault complexity. Computational cost increases by 7% when accounting for off-fault plasticity in the demonstrating application. Our results imply that the combination of fully 3D dynamic modelling, complex fault geometries, and off-fault plastic yielding is important to realistically capture dynamic rupture transfers in natural fault systems.

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.

Rupture Dynamics and Seismic Radiation on Rough Faults for Simulation-Based PSHA

NASA Astrophysics Data System (ADS)

Mai, P. M.; Galis, M.; Thingbaijam, K. K. S.; Vyas, J. C.; Dunham, E. M.

2017-12-01

Simulation-based ground-motion predictions may augment PSHA studies in data-poor regions or provide additional shaking estimations, incl. seismic waveforms, for critical facilities. Validation and calibration of such simulation approaches, based on observations and GMPE's, is important for engineering applications, while seismologists push to include the precise physics of the earthquake rupture process and seismic wave propagation in 3D heterogeneous Earth. Geological faults comprise both large-scale segmentation and small-scale roughness that determine the dynamics of the earthquake rupture process and its radiated seismic wavefield. We investigate how different parameterizations of fractal fault roughness affect the rupture evolution and resulting near-fault ground motions. Rupture incoherence induced by fault roughness generates realistic ω-2 decay for high-frequency displacement amplitude spectra. Waveform characteristics and GMPE-based comparisons corroborate that these rough-fault rupture simulations generate realistic synthetic seismogram for subsequent engineering application. Since dynamic rupture simulations are computationally expensive, we develop kinematic approximations that emulate the observed dynamics. Simplifying the rough-fault geometry, we find that perturbations in local moment tensor orientation are important, while perturbations in local source location are not. Thus, a planar fault can be assumed if the local strike, dip, and rake are maintained. The dynamic rake angle variations are anti-correlated with local dip angles. Based on a dynamically consistent Yoffe source-time function, we show that the seismic wavefield of the approximated kinematic rupture well reproduces the seismic radiation of the full dynamic source process. Our findings provide an innovative pseudo-dynamic source characterization that captures fault roughness effects on rupture dynamics. Including the correlations between kinematic source parameters, we present a new pseudo-dynamic rupture modeling approach for computing broadband ground-motion time-histories for simulation-based PSHA

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.

The Atmospheric Pressure and Temperature Seem to Have No Effect on the Incidence of Rupture of Abdominal Aortic Aneurysm in a Mid-European Region.

PubMed

Majd, Payman; Ahmad, Wael; Luebke, Thomas; Brunkwall, Jan Sigge

2017-07-01

This study aims to examine the relationship between weather changes (atmospheric pressure and temperature) and incidence of rupture of abdominal aortic aneurysm (AAA). All patients with ruptured infrarenal AAA and who were referred to our institution between August 1998 and August 2015 were prospectively entered into a database of which a retrospective review of a ruptured AAA was performed. The needed information about the daily atmospheric pressure and air temperature could be extracted from the meteorological unit in Cologne. During the study period (6,225 days), a total number of 154 patients with confirmed ruptured AAA were identified. Basic patients' characteristics are tabulated. The mean daily atmospheric pressure during the study was 1,004.04 ± 8.79 mBar ranging from 965.40-1031.80 mBar. The mean atmospheric pressure on the days of rupture was 1,004.03 vs. 1,004.68 on those days when no rupture occurred (P = 0.34). The mean atmospheric pressure on the day of rupture and that on the preceding day was not significantly different (1,004.78 vs. 1,005.44 with P = 0.13). The air temperature (10.62 ± 6.25 vs. 10.77 ± 6.83°C, P = 0.787) was equally distributed between days of rupture events and control days. The present study could not show a significant association between the monthly and seasonal difference in atmospheric pressure and the prevalence of AAA rupture as it has been supposed by previous studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Creeping Guanxian-Anxian Fault ruptured in the 2008 Mw 7.9 Wenchuan earthquake

NASA Astrophysics Data System (ADS)

He, X.; Li, H.; Wang, H.; Zhang, L.; Si, J.

2017-12-01

Crustal active faults can slide either steadily by aseismic creep, or abruptly by earthquake rupture. Creep can relax continuously the stress and reduce the occurrence of large earthquakes. Identifying the behaviors of active faults plays a crucial role in predicting and preventing earthquake disasters. Based on multi-scale structural analyses for fault rocks from the GAF surface rupture zone and the Wenchuan Earthquake Fault Zone Science Drilling borehole 3P, we detect the analogous "mylonite structures" develop pervasively in GAF fault rocks. Such specious "ductile deformations", showing intensive foliation, spindly clasts, tailing structure, "boudin structure", "augen structure" and S-C fabrics, are actually formed in brittle faulting, which indicates the creeping behavior of the GAF. Furthermore, some special structures hint the creeping mechanism. The cracks and veins developed in fractured clasts imply pressure and fluid control in the faulting. Under the effect of fluid, clasts are dissolved in pressing direction, and solutions are transferred to stress vacancy area at both ends of clasts and deposit to regenerate clay minerals. The clasts thus present spindly shape and are surrounded by orientational clay minerals constituting continuous foliation structure. The clay minerals are dominated by phyllosilicates that can weaken faults and promote pressure solution. Therefore, pressure solution creep and phyllosilicates weakening reasonably interpret the creeping of GAF. Additionally, GPS velocity data show slip rates of the GAF are respectively 1.5 and 12 mm/yr during 1998-2008 and 2009-2011, which also indicate the GAF is in creeping during interseismic period. According to analysis on aftershocks distribution and P-wave velocity with depth and geological section in the Longmenshan thrust belt, we suggest the GAF is creeping in shallow (<10 km) and locked in deep (10-20 km). Comprehensive research shows stress propagated from the west was concentrated near the Yingxiu-Beichuan Fault (YBF) and GAF zones. As stress accumulation reached the limit, the YBF and GAF zones were simultaneously ruptured in 2008 Mw 7.9 Wenchuan earthquake, but the rupture area of the GAF was relatively small due to the presence of shallow creep that relaxed the partial stress.

Precarious rock and overturned transformer evidence for ground shaking in the Ms 7.7 Kern County earthquake: An analog for disastrous shaking from a major thrust fault in the Los Angeles basin

USGS Publications Warehouse

Brune, J.N.; Anooshehpoor, A.; Shi, B.; Zheng, Yen

2004-01-01

Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 Ms 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations). On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.

Rupture processes of the 2012 September 5 Mw 7.6 Nicoya, Costa Rica earthquake constrained by improved geodetic and seismological observations

NASA Astrophysics Data System (ADS)

Liu, Chengli; Zheng, Yong; Xiong, Xiong; Wang, Rongjiang; López, Allan; Li, Jun

2015-10-01

On 2012 September 5, the anticipated interplate thrust earthquake ruptured beneath the Nicoya peninsula in northwestern Costa Rica close to the Middle America trench, with a magnitude Mw 7.6. Extensive co-seismic observations were provided by dense near-field strong ground motion, Global Positioning Systems (GPS) networks and teleseismic recordings from global seismic networks. The wealthy data sets available for the 2012 Mw 7.6 Nicoya earthquake provide a unique opportunity to investigate the details of the rupture process of this earthquake. By implementing a non-linear joint inversion with high-rate GPS waveform, more static GPS offsets, strong-motion data and teleseismic body waveform, we obtained a robust and accurate rupture model of the 2012 Mw 7.6 Nicoya earthquake. The earthquake is dominantly a pure thrust component with a maximum slip of 3.5 m, and the main large slip patch is located below the hypocentre, spanning ˜50 km along dip and ˜110 km along strike. The static stress drop is about 3.4 MPa. The total seismic moment of our preferred model is 3.46 × 1020 N m, which gives Mw = 7.6. Due to the fast rupture velocity, most of the seismic moment was released within 70 s. The largest slip patch directly overlaps the interseismic locked region identified by geodetic observations and extends downdip to the intersection with the upper plate Moho. We also find that there is a complementary pattern between the distribution of aftershocks and the co-seismic rupture; most aftershocks locate in the crust of the upper plate and are possibly induced by the stress change caused by the large slip patch.

Detailed source process of the 2007 Tocopilla earthquake.

NASA Astrophysics Data System (ADS)

Peyrat, S.; Madariaga, R.; Campos, J.; Asch, G.; Favreau, P.; Bernard, P.; Vilotte, J.

2008-05-01

We investigated the detail rupture process of the Tocopilla earthquake (Mw 7.7) of the 14 November 2007 and of the main aftershocks that occurred in the southern part of the North Chile seismic gap using strong motion data. The earthquake happen in the middle of the permanent broad band and strong motion network IPOC newly installed by GFZ and IPGP, and of a digital strong-motion network operated by the University of Chile. The Tocopilla earthquake is the last large thrust subduction earthquake that occurred since the major Iquique 1877 earthquake which produced a destructive tsunami. The Arequipa (2001) and Antofagasta (1995) earthquakes already ruptured the northern and southern parts of the gap, and the intraplate intermediate depth Tarapaca earthquake (2005) may have changed the tectonic loading of this part of the Peru-Chile subduction zone. For large earthquakes, the depth of the seismic rupture is bounded by the depth of the seismogenic zone. What controls the horizontal extent of the rupture for large earthquakes is less clear. Factors that influence the extent of the rupture include fault geometry, variations of material properties and stress heterogeneities inherited from the previous ruptures history. For subduction zones where structures are not well known, what may have stopped the rupture is not obvious. One crucial problem raised by the Tocopilla earthquake is to understand why this earthquake didn't extent further north, and at south, what is the role of the Mejillones peninsula that seems to act as a barrier. The focal mechanism was determined using teleseismic waveforms inversion and with a geodetic analysis (cf. Campos et al.; Bejarpi et al., in the same session). We studied the detailed source process using the strong motion data available. This earthquake ruptured the interplate seismic zone over more than 150 km and generated several large aftershocks, mainly located south of the rupture area. The strong-motion data show clearly two S-waves arrivals, allowing the localization of the 2 sources. The main shock started north of the segment close to Tocopilla. The rupture propagated southward. The second source was identified to start about 20 seconds later and was located 50 km south from the hypocenter. The network configuration provides a good resolution for the inverted slip distribution in the north-south direction, but a lower resolution for the east-west extent of the slip. However, this study of the source process of this earthquake shows a complex source with at least two slip asperities of different dynamical behavior.

Role of laparoscopy as a minimally invasive procedure in treatment of ruptured uterine scar during second-trimester induction of abortion.

PubMed

Zheng, Yanmei; Jiang, Qiaoying; Lv, Ya-Er; Liu, Feng; Yang, Liwei

2016-04-01

Uterine rupture is an uncommon complication following termination of pregnancy and is usually accompanied by severe lower abdominal pain and shock caused by intra-abdominal hemorrhage. Laparotomy should be carried out promptly in order to repair the uterus or even to resect the uterus. Here we present a case of uterine rupture of a scarred uterus, which occurred during a second-trimester induced abortion. The patient was successfully treated by laparoscopy with the help of laparoscopic ultrasound. This case suggests an alternative, effective approach to the diagnosis and treatment of uterine rupture. © 2015 Japan Society of Obstetrics and Gynecology.

Subcritical crack growth in fibrous materials

NASA Astrophysics Data System (ADS)

Santucci, S.; Cortet, P.-P.; Deschanel, S.; Vanel, L.; Ciliberto, S.

2006-05-01

We present experiments on the slow growth of a single crack in a fax paper sheet submitted to a constant force F. We find that statistically averaged crack growth curves can be described by only two parameters: the mean rupture time τ and a characteristic growth length ζ. We propose a model based on a thermally activated rupture process that takes into account the microstructure of cellulose fibers. The model is able to reproduce the shape of the growth curve, the dependence of ζ on F as well as the effect of temperature on the rupture time τ. We find that the length scale at which rupture occurs in this model is consistently close to the diameter of cellulose microfibrils.

Long-period spectral features of the Sumatra-Andaman 2004 earthquake rupture process

NASA Astrophysics Data System (ADS)

Clévédé, E.; Bukchin, B.; Favreau, P.; Mostinskiy, A.; Aoudia, A.; Panza, G. F.

2012-12-01

The goal of this study is to investigate the spatial variability of the seismic radiation spectral content of the Sumatra-Andaman 2004 earthquake. We determine the integral estimates of source geometry, duration and rupture propagation given by the stress glut moments of total degree 2 of different source models. These models are constructed from a single or a joint use of different observations including seismology, geodesy, altimetry and tide gauge data. The comparative analysis shows coherency among the different models and no strong contradictions are found between the integral estimates of geodetic and altimetric models, and those retrieved from very long period seismic records (up to 2000-3000 s). The comparison between these results and the integral estimates derived from observed surface wave spectra in period band from 500 to 650 s suggests that the northern part of the fault (to the north of 8°N near Nicobar Islands) did not radiate long period seismic waves, that is, period shorter than 650 s at least. This conclusion is consistent with the existing composite short and long rise time tsunami model: with short rise time of slip in the southern part of the fault and very long rise time of slip at the northern part. This complex space-time slip evolution can be reproduced by a simple dynamic model of the rupture assuming a crude phenomenological mechanical behaviour of the rupture interface at the fault scales combining an effective slip-controlled exponential weakening effect, related to possible friction and damage breakdown processes of the fault zone, and an effective linear viscous strengthening effect, related to possible interface lubrication processes. While the rupture front speed remains unperturbed with initial short slip duration, a slow creep wave propagates behind the rupture front in the case of viscous effects accounting for the long slip duration and the radiation characteristics in the northern segment.

Width of surface rupture zone for thrust earthquakes: implications for earthquake fault zoning

NASA Astrophysics Data System (ADS)

Boncio, Paolo; Liberi, Francesca; Caldarella, Martina; Nurminen, Fiia-Charlotta

2018-01-01

The criteria for zoning the surface fault rupture hazard (SFRH) along thrust faults are defined by analysing the characteristics of the areas of coseismic surface faulting in thrust earthquakes. Normal and strike-slip faults have been deeply studied by other authors concerning the SFRH, while thrust faults have not been studied with comparable attention. Surface faulting data were compiled for 11 well-studied historic thrust earthquakes occurred globally (5.4 ≤ M ≤ 7.9). Several different types of coseismic fault scarps characterize the analysed earthquakes, depending on the topography, fault geometry and near-surface materials (simple and hanging wall collapse scarps, pressure ridges, fold scarps and thrust or pressure ridges with bending-moment or flexural-slip fault ruptures due to large-scale folding). For all the earthquakes, the distance of distributed ruptures from the principal fault rupture (r) and the width of the rupture zone (WRZ) were compiled directly from the literature or measured systematically in GIS-georeferenced published maps. Overall, surface ruptures can occur up to large distances from the main fault ( ˜ 2150 m on the footwall and ˜ 3100 m on the hanging wall). Most of the ruptures occur on the hanging wall, preferentially in the vicinity of the principal fault trace ( > ˜ 50 % at distances < ˜ 250 m). The widest WRZ are recorded where sympathetic slip (Sy) on distant faults occurs, and/or where bending-moment (B-M) or flexural-slip (F-S) fault ruptures, associated with large-scale folds (hundreds of metres to kilometres in wavelength), are present. A positive relation between the earthquake magnitude and the total WRZ is evident, while a clear correlation between the vertical displacement on the principal fault and the total WRZ is not found. The distribution of surface ruptures is fitted with probability density functions, in order to define a criterion to remove outliers (e.g. 90 % probability of the cumulative distribution function) and define the zone where the likelihood of having surface ruptures 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 (the highest level of SM, i.e. Level 3 SM according to Italian guidelines). In the absence of such a very detailed study (basic SM, i.e. Level 1 SM of Italian guidelines) a width of ˜ 840 m (90 % probability from "simple thrust" database of distributed ruptures, excluding B-M, F-S and Sy fault ruptures) is suggested to be sufficiently precautionary. For more detailed SM, where the fault is carefully mapped, one must consider that the highest SFRH is concentrated in a narrow zone, ˜ 60 m in width, that should be considered as a fault avoidance zone (more than one-third of the distributed ruptures are expected to occur within this zone). The fault rupture hazard zones should be asymmetric compared to the trace of the principal fault. The average footwall to hanging wall ratio (FW : HW) is close to 1 : 2 in all analysed cases. These criteria are applicable to "simple thrust" faults, without considering possible B-M or F-S fault ruptures due to large-scale folding, and without considering sympathetic slip on distant faults. Areas potentially susceptible to B-M or F-S fault ruptures should have their own zones of fault rupture hazard that can be defined by detailed knowledge of the structural setting of the area (shape, wavelength, tightness and lithology of the thrust-related large-scale folds) and by geomorphic evidence of past secondary faulting. Distant active faults, potentially susceptible to sympathetic triggering, should be zoned as separate principal faults. The entire database of distributed ruptures (including B-M, F-S and Sy fault ruptures) can be useful in poorly known areas, in order to assess the extent of the area within which potential sources of fault displacement hazard can be present. The results from this study and the database made available in the Supplement can be used for improving the attenuation relationships for distributed faulting, with possible applications in probabilistic studies of fault displacement hazard.

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.

Seafloor Deformation and Localized Source Mechanisms of the 2011 M9 Tohoku Earthquake and Tsunami.

NASA Astrophysics Data System (ADS)

Masterlark, T.; Grilli, S. T.; Tappin, D. R.; Kirby, J. T.

2012-12-01

The 2011 M9 Tohoku Earthquake (TE) ruptured the interface separating the Pacific and Okhotsk Plates. This rupture was about hundred kilometers in the along-strike direction and 200 kilometers in the down-dip direction. The TE was primarily thrust having substantial slip along the up-dip portion of the rupture, near the Japan Trench. The regional-scale seafloor deformation from the TE triggered a tsunami with run-ups of a few tens of meters that caused extensive damage along the east coast of Tohoku, Japan. We construct finite element models (FEMs) to simulate the deformation caused by a distribution of coseismic slip along the curved rupture surface of the TE. The FEMs include a distribution of material properties that accounts for the subduction zone structure -a weak forearc, volcanic arc, and backarc basin of the overriding Okhotsk Plate overriding the relatively strong subducting slab that is capped by basaltic oceanic crust. The coseismic rupture is simulated as a distribution of elastic dislocations along the interface separating the forearc of the overriding plate and the oceanic crust of the subducting slab. The slip distribution is calibrated to both onshore and offshore geodetic data, using linear least-squares inverse methods with FEM-generated Greens Functions and second order regularization. The regularization is imposed with a conductance matrix, constructed using Galerkin's Method to account for the curvilinear relationships among the dislocating node pairs. The estimated slip distribution is generally characterized as a few tens of meters of slip over the entire rupture, with greater slip magnitudes (>50 meters) concentrated up-dip and near the Japan Trench. The offshore geodetic data provide critical constraints for the location of the polarity reversal of predicted seafloor vertical deformation. Wave models excited by the predicted regional-scale seafloor deformation generally well predict observed tsunami run-ups and the vertical displacement magnitudes of low frequency waves of coastal GPS buoys. However, coastal areas near Sanriku, Japan experienced anomalously high run-ups of 40 meters and local offshore GPS buoys indicate high frequency waveforms that are incompatible with the coseismic seafloor deformation of the TE. These observations require a localized deformation source near the Japan Trench and just to the north of the TE rupture zone, which models solely based on tsunami waveform inversion predict. Others suggest that a submarine mass failure at this location, presumably triggered by the TE, can excite such waveforms. In this study, we investigate an alternative hypothesis that localized splay faulting, also presumably triggered by the TE, can excite the anomalous waveforms. To do so, we will estimate plausible suites of splay fault and slip parameters that can account for the anomalously high magnitude and high frequency tsunami waves sourced from a localized area near the Japan Trench and north of the TE rupture.

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

PubMed

Broadhurst, Matthew S; Akst, Lee M; Burns, James A; Kobler, James B; Heaton, James T; Anderson, R Rox; Zeitels, Steven M

2007-02-01

Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Comparison of Observed Spatio-temporal Aftershock Patterns with Earthquake Simulator Results

NASA Astrophysics Data System (ADS)

Kroll, K.; Richards-Dinger, K. B.; Dieterich, J. H.

2013-12-01

Due to the complex nature of faulting in southern California, knowledge of rupture behavior near fault step-overs is of critical importance to properly quantify and mitigate seismic hazards. Estimates of earthquake probability are complicated by the uncertainty that a rupture will stop at or jump a fault step-over, which affects both the magnitude and frequency of occurrence of earthquakes. In recent years, earthquake simulators and dynamic rupture models have begun to address the effects of complex fault geometries on earthquake ground motions and rupture propagation. Early models incorporated vertical faults with highly simplified geometries. Many current studies examine the effects of varied fault geometry, fault step-overs, and fault bends on rupture patterns; however, these works are limited by the small numbers of integrated fault segments and simplified orientations. The previous work of Kroll et al., 2013 on the northern extent of the 2010 El Mayor-Cucapah rupture in the Yuha Desert region uses precise aftershock relocations to show an area of complex conjugate faulting within the step-over region between the Elsinore and Laguna Salada faults. Here, we employ an innovative approach of incorporating this fine-scale fault structure defined through seismological, geologic and geodetic means in the physics-based earthquake simulator, RSQSim, to explore the effects of fine-scale structures on stress transfer and rupture propagation and examine the mechanisms that control aftershock activity and local triggering of other large events. We run simulations with primary fault structures in state of California and northern Baja California and incorporate complex secondary faults in the Yuha Desert region. These models produce aftershock activity that enables comparison between the observed and predicted distribution and allow for examination of the mechanisms that control them. We investigate how the spatial and temporal distribution of aftershocks are affected by changes to model parameters such as shear and normal stress, rate-and-state frictional properties, fault geometry, and slip rate.

Endovascular coil embolization of aneurysm neck for the treatment of ruptured intracranial aneurysm with bleb formation

PubMed Central

Wan, Jun; Gu, Weijin; Zhang, Xiaolong; Geng, Daoying; Lu, Gang; Huang, Lei; Zhang, Lei; Ge, Liang; Ji, Lihua

2014-01-01

Background Ruptured intracranial aneurysm (ICA) with bleb formation (RICABF) is a special type of ruptured ICA. However, the exact role and effectiveness of endovascular coil embolization (ECE) in RICABF is unknown. We aimed to investigate the effectiveness and safety of ECE of aneurysm neck for RICABF treatment. Material/Methods We retrospectively assessed consecutive patients who were hospitalized in our endovascular intervention center between October 2004 and May 2012. Overall, 86 patients underwent ECE of aneurysm neck for 86 RICABF. Treatments outcomes included secondary rupture/bleeding rate, aneurysm neck embolization rate, residual/recurrent aneurysm, intraoperative incidents, and post-embolization complications, as well as improvements in the Glasgow outcome scale (extended) (GOS-E). Results Complete occlusion was achieved in 72 aneurysms (72/86, 83.7%), while 12 aneurysms (12/86, 14.0%) had a residual neck, and 2 aneurysms (2/86, 2.3%) had a residual aneurysm. The postoperative GOS-E was 3 in 3 patients (3.5%), 4 in 10 patients (11.6%), and 5 in 73 patients (84.9%). Follow-up angiography was performed in all patients (mean 9.0 months, interquartile range of 9.0). Recurrence was found in 3 patients (3/86, 3.5%). No aneurysm rupture or bleeding was reported. Conclusions Our mid-term follow-up study showed that ECE of aneurysm neck was an effective and safe treatment modality for RICABF. The long-term effectiveness and safety of this interventional radiology technique need to be investigated in prospective and comparative studies. PMID:24986761

Robust real-time fault tracking for the 2011 Mw 9.0 Tohoku earthquake based on the phased-array-interference principle

NASA Astrophysics Data System (ADS)

Zhang, Yong; Wang, Rongjiang; Parolai, Stefano; Zschau, Jochen

2013-04-01

Based on the principle of the phased array interference, we have developed an Iterative Deconvolution Stacking (IDS) method for real-time kinematic source inversion using near-field strong-motion and GPS networks. In this method, the seismic and GPS stations work like an array radar. The whole potential fault area is scanned patch by patch by stacking the apparent source time functions, which are obtained through deconvolution between the recorded seismograms and synthetic Green's functions. Once some significant source signals are detected any when and where, their signatures are removed from the observed seismograms. The procedure is repeated until the accumulative seismic moment being found converges and the residual seismograms are reduced below the noise level. The new approach does not need any artificial constraint used in the source parameterization such as, for example, fixing the hypocentre, restricting the rupture velocity and rise time, etc. Thus, it can be used for automatic real-time source inversion. In the application to the 2011 Tohoku earthquake, the IDS method is proved to be robust and reliable on the fast estimation of moment magnitude, fault area, rupture direction, and maximum slip, etc. About at 100 s after the rupture initiation, we can get the information that the rupture mainly propagates along the up-dip direction and causes a maximum slip of 17 m, which is enough to release a tsunami early warning. About two minutes after the earthquake occurrence, the maximum slip is found to be 31 m, and the moment magnitude reaches Mw8.9 which is very close to the final moment magnitude (Mw9.0) of this earthquake.

Missing link between the Hayward and Rodgers Creek faults

PubMed Central

Watt, Janet; Ponce, David; Parsons, Tom; Hart, Patrick

2016-01-01

The next major earthquake to strike the ~7 million residents of the San Francisco Bay Area will most likely result from rupture of the Hayward or Rodgers Creek faults. Until now, the relationship between these two faults beneath San Pablo Bay has been a mystery. Detailed subsurface imaging provides definitive evidence of active faulting along the Hayward fault as it traverses San Pablo Bay and bends ~10° to the right toward the Rodgers Creek fault. Integrated geophysical interpretation and kinematic modeling show that the Hayward and Rodgers Creek faults are directly connected at the surface—a geometric relationship that has significant implications for earthquake dynamics and seismic hazard. A direct link enables simultaneous rupture of the Hayward and Rodgers Creek faults, a scenario that could result in a major earthquake (M = 7.4) that would cause extensive damage and loss of life with global economic impact. PMID:27774514

Missing link between the Hayward and Rodgers Creek faults

USGS Publications Warehouse

Watt, Janet; Ponce, David A.; Parsons, Thomas E.; Hart, Patrick E.

2016-01-01

The next major earthquake to strike the ~7 million residents of the San Francisco Bay Area will most likely result from rupture of the Hayward or Rodgers Creek faults. Until now, the relationship between these two faults beneath San Pablo Bay has been a mystery. Detailed subsurface imaging provides definitive evidence of active faulting along the Hayward fault as it traverses San Pablo Bay and bends ~10° to the right toward the Rodgers Creek fault. Integrated geophysical interpretation and kinematic modeling show that the Hayward and Rodgers Creek faults are directly connected at the surface—a geometric relationship that has significant implications for earthquake dynamics and seismic hazard. A direct link enables simultaneous rupture of the Hayward and Rodgers Creek faults, a scenario that could result in a major earthquake (M = 7.4) that would cause extensive damage and loss of life with global economic impact.

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

NASA Technical Reports Server (NTRS)

Schuon, S. R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life.

Rupture models with dynamically determined breakdown displacement

USGS Publications Warehouse

Andrews, D.J.

2004-01-01

The critical breakdown displacement, Dc, in which friction drops to its sliding value, can be made dependent on event size by specifying friction to be a function of variables other than slip. Two such friction laws are examined here. The first is designed to achieve accuracy and smoothness in discrete numerical calculations. Consistent resolution throughout an evolving rupture is achieved by specifying friction as a function of elapsed time after peak stress is reached. Such a time-weakening model produces Dc and fracture energy proportional to the square root of distance rupture has propagated in the case of uniform stress drop. The second friction law is more physically motivated. Energy loss in a damage zone outside the slip zone has the effect of increasing Dc and limiting peak slip velocity (Andrews, 1976). This article demonstrates a converse effect, that artificially limiting slip velocity on a fault in an elastic medium has a toughening effect, increasing fracture energy and Dc proportionally to rupture propagation distance in the case of uniform stress drop. Both the time-weakening and the velocity-toughening models can be used in calculations with heterogeneous stress drop.

Source model of an earthquake doublet that occurred in a pull-apart basin along the Sumatran fault, Indonesia

NASA Astrophysics Data System (ADS)

Nakano, M.; Kumagai, H.; Toda, S.; Ando, R.; Yamashina, T.; Inoue, H.; Sunarjo

2010-04-01

On 2007 March 6, an earthquake doublet occurred along the Sumatran fault, Indonesia. The epicentres were located near Padang Panjang, central Sumatra, Indonesia. The first earthquake, with a moment magnitude (Mw) of 6.4, occurred at 03:49 UTC and was followed two hours later (05:49 UTC) by an earthquake of similar size (Mw = 6.3). We studied the earthquake doublet by a waveform inversion analysis using data from a broadband seismograph network in Indonesia (JISNET). The focal mechanisms of the two earthquakes indicate almost identical right-lateral strike-slip faults, consistent with the geometry of the Sumatran fault. Both earthquakes nucleated below the northern end of Lake Singkarak, which is in a pull-apart basin between the Sumani and Sianok segments of the Sumatran fault system, but the earthquakes ruptured different fault segments. The first earthquake occurred along the southern Sumani segment and its rupture propagated southeastward, whereas the second one ruptured the northern Sianok segment northwestward. Along these fault segments, earthquake doublets, in which the two adjacent fault segments rupture one after the other, have occurred repeatedly. We investigated the state of stress at a segment boundary of a fault system based on the Coulomb stress changes. The stress on faults increases during interseismic periods and is released by faulting. At a segment boundary, on the other hand, the stress increases both interseismically and coseismically, and may not be released unless new fractures are created. Accordingly, ruptures may tend to initiate at a pull-apart basin. When an earthquake occurs on one of the fault segments, the stress increases coseismically around the basin. The stress changes caused by that earthquake may trigger a rupture on the other segment after a short time interval. We also examined the mechanism of the delayed rupture based on a theory of a fluid-saturated poroelastic medium and dynamic rupture simulations incorporating a rheological velocity hardening effect. These models of the delayed rupture can qualitatively explain the observations, but further studies, especially based on the rheological effect, are required for quantitative studies.

Evaluating a kinematic method for generating broadband ground motions for great subduction zone earthquakes: Application to the 2003 Mw 8.3 Tokachi‐Oki earthquake

USGS Publications Warehouse

Wirth, Erin A.; Frankel, Arthur; Vidale, John E.

2017-01-01

We compare broadband synthetic seismograms with recordings of the 2003 Mw">MwMw 8.3 Tokachi‐Oki earthquake to evaluate a compound rupture model, in which slip on the fault consists of multiple high‐stress‐drop asperities superimposed on a background slip distribution with longer rise times. Low‐frequency synthetics (<1  Hz"><1  Hz<1  Hz) are calculated using deterministic, 3D finite‐difference simulations and are combined with high‐frequency (>1  Hz">>1  Hz>1  Hz) stochastic synthetics using a matched filter at 1 Hz. We show that this compound rupture model and overall approach accurately reproduces waveform envelopes and observed response spectral accelerations (SAs) from the Tokachi‐Oki event. We find that sufficiently short subfault rise times (i.e., <∼1–2  s"><∼1–2  s<∼1–2  s) are necessary to reproduce energy ∼1  Hz">∼1  Hz∼1  Hz. This is achieved by either (1) including distinct subevents with short rise times, as may be suggested by the Tokachi‐Oki data, or (2) imposing a fast‐slip velocity over the entire rupture area. We also include a systematic study on the effects of varying several kinematic rupture parameters. We find that simulated strong ground motions are sensitive to the average rupture velocity and coherence of the rupture front, with more coherent ruptures yielding higher response SAs. We also assess the effects of varying the average slip velocity and the character (i.e., area, magnitude, and location) of high‐stress‐drop subevents. Even in the absence of precise constraints on these kinematic rupture parameters, our simulations still reproduce major features in the Tokachi‐Oki earthquake data, supporting its accuracy in modeling future large earthquakes.

Deep slip distribution and rupture directivity enhance shaking during the 2017 Mw 8.2 Chiapas earthquake

NASA Astrophysics Data System (ADS)

Chen, K.; Feng, W.; Liu, Z.; Song, T.

2017-12-01

As the largest intraplate normal faulting event ever recorded, the 2017 Mw 8.2 Mexico Chiapas earthquake is strongly felt as far as Mexico City that is almost 720 km northwest of the epicenter, causing tsunami with a maximum wave height of about six feet. In this contribution, we model this event by joint inversion of static GPS offsets, 1-Hz GPS displacement waveforms, InSAR observations and teleseismic P waves. To validate the preferred model determined from this study, we run tsunami simulation based on the synthetic sea floor deformation and compare it with tsunami records. Our results show that this earthquake took place near the "bending point" of subduction interface in SLAB 1.0, where seismic energy was accumulated. It propagated mainly unilaterally towards to the northwest of the epicenter at a relatively high speed ( 2.8 km/s), and at least two asperities were identified. The dominant one is centered at depth from 40 to 60 km while the second patch is relatively shallow at about 20 km depth. The peak slip is approximately 12 meters and the total released energy is 2.7e+21 Nm, equal to Mw 8.2. Note that the peak ground acceleration (PGA) recorded along the propagation direction is tens of times larger than that recorded in the opposite direction with nearly identical epicentral distances (about 700 km), and clear co-seismic dynamic displacement waveforms (up to 5 cm) are observed at a GPS station with 1450 km epicentral distance. Based on these preliminary results, we suggest that the deep slip in the low attenuation mantle and rupture directivity may contribute to the nationwide ground shaking, and the shallow slip induces evident vertical surface displacements, which amplify local tsunami heights. Keywords: Chiapas earthquake, joint inversion, tsunami, rupture directivity

Real-Time Science on Social Media: The Example of Twitter in the Minutes, Hours, Days after the 2015 M7.8 Nepal Earthquake

NASA Astrophysics Data System (ADS)

Lomax, A.; Bossu, R.; Mazet-Roux, G.

2015-12-01

Scientific information on disasters such as earthquakes typically comes firstly from official organizations, news reports and interviews with experts, and later from scientific presentations and peer-reviewed articles. With the advent of the Internet and social media, this information is available in real-time from automated systems and within a dynamic, collaborative interaction between scientific experts, responders and the public. After the 2015 M7.8 Nepal earthquake, Twitter Tweets from earth scientists* included information, analysis, commentary and discussion on earthquake parameters (location, size, mechanism, rupture extent, high-frequency radiation, …), earthquake effects (distribution of felt shaking and damage, triggered seismicity, landslides, …), earthquake rumors (e.g. the imminence of a larger event) and other earthquake information and observations (aftershock forecasts, statistics and maps, source and regional tectonics, seismograms, GPS, InSAR, photos/videos, …).In the future (while taking into account security, false or erroneous information and identity verification), collaborative, real-time science on social media after a disaster will give earlier and better scientific understanding and dissemination of public information, and enable improved emergency response and disaster management.* A sample of scientific Tweets after the 2015 Nepal earthquake: In the first minutes: "mb5.9 Mwp7.4 earthquake Nepal 2015.04.25-06:11:25UTC", "Major earthquake shakes Nepal 8 min ago", "Epicenter between Pokhara and Kathmandu", "Major earthquake shakes Nepal 18 min ago. Effects derived from witnesses' reports". In the first hour: "shallow thrust faulting to North under Himalayas", "a very large and shallow event ... Mw7.6-7.7", "aftershocks extend east and south of Kathmandu, so likely ruptured beneath city", "Valley-blocking landslides must be a very real worry". In the first day: "M7.8 earthquake in Nepal 2hr ago: destructive in Kathmandu Valley and widely felt in India", "USGS pager v.3 contains initial fatality & economic loss estimates", "analysis of seismic waves … shows fault rupture lasted 80 sec, shaking longer", "aftershocks suggests rupture zone, directivity and shaking intensity".

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.

Mitral Valve Repair Using ePTFE Sutures for Ruptured Mitral Chordae Tendineae: A Computational Simulation Study

PubMed Central

Rim, Yonghoon; Laing, Susan T.; McPherson, David D.; Kim, Hyunggun

2013-01-01

Mitral valve repair using expanded polytetrafluoroethylene (ePTFE) sutures is an established and preferred interventional method to resolve the complex pathophysiologic problems associated with chordal rupture. We developed a novel computational evaluation protocol to determine the effect of the artificial sutures on restoring mitral valve function following valve repair. A virtual mitral valve was created using three-dimensional echocardiographic data in a patient with ruptured mitral chordae tendineae. Virtual repairs were designed by adding artificial sutures between the papillary muscles and the posterior leaflet where the native chordae were ruptured. Dynamic finite element simulations were performed to evaluate pre- and post-repair mitral valve function. Abnormal posterior leaflet prolapse and mitral regurgitation was clearly demonstrated in the mitral valve with ruptured chordae. Following virtual repair to reconstruct ruptured chordae, the severity of the posterior leaflet prolapse decreased and stress concentration was markedly reduced both in the leaflet tissue and the intact native chordae. Complete leaflet coaptation was restored when four or six sutures were utilized. Computational simulations provided quantitative information of functional improvement following mitral valve repair. This novel simulation strategy may provide a powerful tool for evaluation and prediction of interventional treatment for ruptured mitral chordae tendineae. PMID:24072489

Critical Parameters of the Initiation Zone for Spontaneous Dynamic Rupture Propagation

NASA Astrophysics Data System (ADS)

Galis, M.; Pelties, C.; Kristek, J.; Moczo, P.; Ampuero, J. P.; Mai, P. M.

2014-12-01

Numerical simulations of rupture propagation are used to study both earthquake source physics and earthquake ground motion. Under linear slip-weakening friction, artificial procedures are needed to initiate a self-sustained rupture. The concept of an overstressed asperity is often applied, in which the asperity is characterized by its size, shape and overstress. The physical properties of the initiation zone may have significant impact on the resulting dynamic rupture propagation. A trial-and-error approach is often necessary for successful initiation because 2D and 3D theoretical criteria for estimating the critical size of the initiation zone do not provide general rules for designing 3D numerical simulations. Therefore, it is desirable to define guidelines for efficient initiation with minimal artificial effects on rupture propagation. We perform an extensive parameter study using numerical simulations of 3D dynamic rupture propagation assuming a planar fault to examine the critical size of square, circular and elliptical initiation zones as a function of asperity overstress and background stress. For a fixed overstress, we discover that the area of the initiation zone is more important for the nucleation process than its shape. Comparing our numerical results with published theoretical estimates, we find that the estimates by Uenishi & Rice (2004) are applicable to configurations with low background stress and small overstress. None of the published estimates are consistent with numerical results for configurations with high background stress. We therefore derive new equations to estimate the initiation zone size in environments with high background stress. Our results provide guidelines for defining the size of the initiation zone and overstress with minimal effects on the subsequent spontaneous rupture propagation.

Analysis of constant tension-induced rupture of lipid membranes using activation energy.

PubMed

Karal, Mohammad Abu Sayem; Levadnyy, Victor; Yamazaki, Masahito

2016-05-11

The stretching of biomembranes and lipid membranes plays important roles in various physiological and physicochemical phenomena. Here we analyzed the rate constant kp of constant tension-induced rupture of giant unilamellar vesicles (GUVs) as a function of tension σ using their activation energy Ua. To determine the values of kp, we applied constant tension to a GUV membrane using the micropipette aspiration method and observed the rupture of GUVs, and then analyzed these data statistically. First, we investigated the temperature dependence of kp for GUVs of charged lipid membranes composed of negatively charged dioleoylphosphatidylglycerol (DOPG) and electrically neutral dioleoylphosphatidylcholine (DOPC). By analyzing this result, the values of Ua of tension-induced rupture of DOPG/DOPC-GUVs were obtained. Ua decreased with an increase in σ, supporting the classical theory of tension-induced pore formation. The analysis of the relationship between Ua and σ using the theory on the electrostatic interaction effects on the tension-induced rupture of GUVs provided the equation of Ua including electrostatic interaction effects, which well fits the experimental data of the tension dependence of Ua. A constant which does not depend on tension, U0, was also found to contribute significantly to Ua. The Arrhenius equations for kp using the equation of Ua and the parameters determined by the above analysis fit well to the experimental data of the tension dependence of kp for DOPG/DOPC-GUVs as well as for DOPC-GUVs. On the basis of these results, we discussed the possible elementary processes underlying the tension-induced rupture of GUVs of lipid membranes. These results indicate that the Arrhenius equation using the experimentally determined Ua is useful in the analysis of tension-induced rupture of GUVs.

Pulley Ruptures in Rock Climbers: Outcome of Conservative Treatment With the Pulley-Protection Splint-A Series of 47 Cases.

PubMed

Schneeberger, Micha; Schweizer, Andreas

2016-06-01

To evaluate the effectiveness of conservative treatment of finger flexor tendon pulley rupture with a pulley-protection splint (PPS) with regard to reduction in tendon-phalanx distance (TPD) and functional and sport-specific outcomes in a retrospective case series. Tendon-phalanx distance in active forced flexion was measured before and after treatment in ultrasound records. Functional and sport-specific outcomes were evaluated by means of a questionnaire, which also contained instructions for self-measurement of finger range of motion and finger strength. Forty-seven complete pulley ruptures in 45 rock climbers (mean age, 33.4 years; range, 21.8-56.2 years) were included in the study. In the 39 patients who had follow-up ultrasound examination, PPS treatment decreased mean ± SD TPD from 4.4 ± 1.0 mm to 2.3 ± 0.6 mm after A2 pulley rupture and from 2.9 ± 0.7 mm to 2.1 ± 0.5 mm after A4 pulley rupture. Tendon-phalanx distance was reduced in all patients. Finger range of motion (n = 42) and finger strength (n = 22) did not differ significantly between treated and contralateral sides. Of the 43 climbers who completed questionnaires, 38 had regained their previous climbing level a mean 8.8 months after pulley rupture; 1 reported reduced finger dexterity; 39 assessed their treatment results to be good, and 4 to be very good. The PPS is an effective conservative treatment modality for pulley ruptures, which reduces TPD and enables the patient to regain previous finger function. Copyright © 2016 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Shift of semimetal-semiconductor bond direction on “0 1 1” to “1 1 1” Bismuth quazi-two-dimension system

NASA Astrophysics Data System (ADS)

Yazdani, Ahmad; Hamreh, Sajad

2018-03-01

The electronic structure of the nanocrystallines and quasi-two-dimensional systems strongly impressed by the thermodynamic- behavior mainly due to excess of hidden surface free energy. Therefore, the stability of crystalline structure’s change could be related to band-offset of bond rupturing of atomic displacements. whereas for the electronic-structure of "Bi" it seams the competition of L.S and bond exchange should be effectively dominated. Besides all of the characters behave spatial like strong sensitive oxidation here it is supposed that strong correlated electronic structure in the absence of oxygen is resulted on direction of redistribution of surface chemical bond formation before any reconstructive structure. Where • The metallic direction of electronic structure “0 1 1” is changed to “1 1 1” semiconductor direction. • the effect of L.S is more evident on the local density of state while it is not observable around the fermi level. • Strong effect of spin-orbit interaction on splitting of the valance to nearly conduction band around the fermi level is more evident.

The Effects of Vasospasm and Re-Bleeding on the Outcome of Patients with Subarachnoid Hemorrhage from Ruptured Intracranial Aneurysm.

PubMed

Filipce, Venko; Caparoski, Aleksandar

2015-01-01

Vasospasm and re-bleeding after subarachnoid hemorrhage from ruptured intracranial aneurysm are devastating complication that can severely affect the outcome of the patients. We are presenting a series of total number of 224 patients treated and operated at our Department due to subarachnoid hemorrhage, out of which certain number developed vasospasm and re-bleeding. We are evaluating the effect of these complications on the outcome of the patients according to the Glasgow Outcome Scale at the day of discharge. In our experience both vasospasm and ReSAH can significantly influence the outcome of patients with subarachnoid hemorrhage from ruptured intracranial aneurysm.

How does huperzine A enter and leave the binding gorge of acetylcholinesterase? Steered molecular dynamics simulations.

PubMed

Xu, Yechun; Shen, Jianhua; Luo, Xiaomin; Silman, Israel; Sussman, Joel L; Chen, Kaixian; Jiang, Hualiang

2003-09-17

The entering and leaving processes of Huperzine A (HupA) binding with the long active-site gorge of Torpedo californica acetylcholinesterase (TcAChE) have been investigated by using steered molecular dynamics simulations. The analysis of the force required along the pathway shows that it is easier for HupA to bind to the active site of AChE than to disassociate from it, which for the first time interprets at the atomic level the previous experimental result that unbinding process of HupA is much slower than its binding process to AChE. The direct hydrogen bonds, water bridges, and hydrophobic interactions were analyzed during two steered molecular dynamics (SMD) simulations. Break of the direct hydrogen bond needs a great pulling force. The steric hindrance of bottleneck might be the most important factor to produce the maximal rupture force for HupA to leave the binding site but it has a little effect on the binding process of HupA with AChE. Residue Asp72 forms a lot of water bridges with HupA leaving and entering the AChE binding gorge, acting as a clamp to take out HupA from or put HupA into the active site. The flip of the peptide bond between Gly117 and Gly118 has been detected during both the conventional MD and SMD simulations. The simulation results indicate that this flip phenomenon could be an intrinsic property of AChE and the Gly117-Gly118 peptide bond in both HupA bound and unbound AChE structures tends to adopt the native enzyme structure. At last, in a vacuum the rupture force is increased up to 1500 pN while in water solution the greatest rupture force is about 800 pN, which means water molecules in the binding gorge act as lubricant to facilitate HupA entering or leaving the binding gorge.

PIP silicone breast implants: rupture rates based on the explantation of 676 implants in a single surgeon series.

PubMed

Quaba, Omar; Quaba, Awf

2013-09-01

To determine the true rupture rates of PIP implants from a large single surgeon cohort and to assess whether rupture rates varied depending on time of implant insertion. In addition, the efficacy of ultra sound scanning (USS) in determining rupture is examined. Predominantly prospectively based analysis of patient records, investigations and surgical findings. 338 patients (676 implants) were included in the study and they all had removal of their implants. The senior author operated on all patients at some stage of their treatment. 160 patients were imaged pre-operatively with USS. Patients had implants inserted between 1999 and 2007 for cosmetic breast augmentation. A total of 144 ruptured implants were removed from 119 patients, giving a rupture rate of 35.2% per patient and 21.3% per implant over a mean implantation period of 7.8 years. A statistical difference (P < 0.001) in rupture rates between implants inserted prior to 2003 and those inserted from 2003 was demonstrated, with higher failure rates in the latter group. There was a significant difference in rupture rates depending on pocket placement of the implants. The sensitivity and specificity of USS at detecting rupture was 90.6% and 98.3% respectively. A proportion of patients (29.4%) demonstrated loco-regional spread of silicone to the axilla on scanning. Our paper has confirmed high rates of PIP implant failure in the largest published series to date. The significant difference in rupture rates between implants inserted prior to 2003 and those after this time supports the view that industrial silicone was used in the devices after 2003. Implants are more likely to rupture if inserted in the sub muscular plane compared to the sub glandular plane. USS is highly effective at detecting rupture in PIP implants and loco-regional spread is high compared to other devices. We believe this paper provides hard data enabling more informed decision making for patients, clinicians and providers in what remains an active issue affecting thousands of women. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Modeling earthquake magnitudes from injection-induced seismicity on rough faults

NASA Astrophysics Data System (ADS)

Maurer, J.; Dunham, E. M.; Segall, P.

2017-12-01

It is an open question whether perturbations to the in-situ stress field due to fluid injection affect the magnitudes of induced earthquakes. It has been suggested that characteristics such as the total injected fluid volume control the size of induced events (e.g., Baisch et al., 2010; Shapiro et al., 2011). On the other hand, Van der Elst et al. (2016) argue that the size distribution of induced earthquakes follows Gutenberg-Richter, the same as tectonic events. Numerical simulations support the idea that ruptures nucleating inside regions with high shear-to-effective normal stress ratio may not propagate into regions with lower stress (Dieterich et al., 2015; Schmitt et al., 2015), however, these calculations are done on geometrically smooth faults. Fang & Dunham (2013) show that rupture length on geometrically rough faults is variable, but strongly dependent on background shear/effective normal stress. In this study, we use a 2-D elasto-dynamic rupture simulator that includes rough fault geometry and off-fault plasticity (Dunham et al., 2011) to simulate earthquake ruptures under realistic conditions. We consider aggregate results for faults with and without stress perturbations due to fluid injection. We model a uniform far-field background stress (with local perturbations around the fault due to geometry), superimpose a poroelastic stress field in the medium due to injection, and compute the effective stress on the fault as inputs to the rupture simulator. Preliminary results indicate that even minor stress perturbations on the fault due to injection can have a significant impact on the resulting distribution of rupture lengths, but individual results are highly dependent on the details of the local stress perturbations on the fault due to geometric roughness.

Composite Overwrapped Pressure Vessels (COPV) Stress Rupture Test: Part 2. Part 2

NASA Technical Reports Server (NTRS)

Russell, Richard; Flynn, Howard; Forth, Scott; Greene, Nathanael; Kezirian, Michael; Varanauski, Don; Leifeste, Mark; Yoder, Tommy; Woodworth, Warren

2010-01-01

One of the major concerns for the aging Space Shuttle fleet is the stress rupture life of composite overwrapped pressure vessels (COPVs). Stress rupture life of a COPY has been defined as the minimum time during which the composite maintains structural integrity considering the combined effects of stress levels and time. To assist in the evaluation of the aging COPVs in the Orbiter fleet an analytical reliability model was developed. The actual data used to construct this model was from testing of COPVs constructed of similar, but not exactly same materials and pressure cycles as used on Orbiter vessels. Since no actual Orbiter COPV stress rupture data exists the Space Shuttle Program decided to run a stress rupture test to compare to model predictions. Due to availability of spares, the testing was unfortunately limited to one 40" vessel. The stress rupture test was performed at maximum operating pressure at an elevated temperature to accelerate aging. The test was performed in two phases. The first phase, 130 F, a moderately accelerated test designed to achieve the midpoint of the model predicted point reliability. A more aggressive second phase, performed at 160 F, was designed to determine if the test article will exceed the 95% confidence interval ofthe model. In phase 3, the vessel pressure was increased to above maximum operating pressure while maintaining the phase 2 temperature. After reaching enough effectives hours to reach the 99.99% confidence level of the model phase 4 testing began when the temperature was increased to greater than 170 F. The vessel was maintained at phase 4 conditions until it failed after over 3 million effect hours. This paper will discuss the results of this test, it's implications and possible follow-on testing.

Dynamics of viscous liquid bridges inside microchannels subject to external oscillatory flow

NASA Astrophysics Data System (ADS)

Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

2015-02-01

We report on two-dimensional simulations of liquid bridges' dynamics inside microchannels of uniform wettability and subject to an external oscillatory flow rate. The oscillatory flow results in a zero net flow rate and its effects are compared to those of a stationary system. To handle the three phase contact lines motion, Cahn-Hilliard diffuse-interface formulation was used and the flow equations were solved using the finite element method with adaptively refined unstructured grids. The results indicate that the liquid bridge responds in three different ways depending on the substrate wettability properties and the frequency of the oscillatory flow. In particular below a critical frequency, the liquid bridge will rupture when the channel walls are philic or detach from the surface when they are phobic. However, at high frequencies, the liquid bridge shows a perpetual periodic oscillatory motion for both philic and phobic surfaces. Furthermore, an increase in the frequency of the flow velocity results in stabilization effects and a behavior approaching that of the stationary system where no rupture or detachment can be observed. This stable behavior is the direct result of less deformation of the liquid bridge due to the fast flow direction change and motion of contact lines on the solid substrate. Moreover, it was found that the flow velocity is out of phase with the footprint and throat lengths and that the latter two also show a phase difference. These differences were explained in terms of the motion of the two contact lines on the solid substrates and the deformation of the two fluid-fluid interfaces.

Dynamics of viscous liquid bridges inside microchannels subject to external oscillatory flow.

PubMed

Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

2015-02-01

We report on two-dimensional simulations of liquid bridges' dynamics inside microchannels of uniform wettability and subject to an external oscillatory flow rate. The oscillatory flow results in a zero net flow rate and its effects are compared to those of a stationary system. To handle the three phase contact lines motion, Cahn-Hilliard diffuse-interface formulation was used and the flow equations were solved using the finite element method with adaptively refined unstructured grids. The results indicate that the liquid bridge responds in three different ways depending on the substrate wettability properties and the frequency of the oscillatory flow. In particular below a critical frequency, the liquid bridge will rupture when the channel walls are philic or detach from the surface when they are phobic. However, at high frequencies, the liquid bridge shows a perpetual periodic oscillatory motion for both philic and phobic surfaces. Furthermore, an increase in the frequency of the flow velocity results in stabilization effects and a behavior approaching that of the stationary system where no rupture or detachment can be observed. This stable behavior is the direct result of less deformation of the liquid bridge due to the fast flow direction change and motion of contact lines on the solid substrate. Moreover, it was found that the flow velocity is out of phase with the footprint and throat lengths and that the latter two also show a phase difference. These differences were explained in terms of the motion of the two contact lines on the solid substrates and the deformation of the two fluid-fluid interfaces.

Wall enhancement on high-resolution magnetic resonance imaging may predict an unsteady state of an intracranial saccular aneurysm.

PubMed

Hu, Peng; Yang, Qi; Wang, Dan-Dan; Guan, Shao-Chen; Zhang, Hong-Qi

2016-10-01

The aneurysm wall has been reported to play a critical role in the formation, development, and even rupture of an aneurysm. We used high-resolution magnetic resonance imaging (HRMRI) to investigate the aneurysm wall in an effort to identify evidence of inflammation invasion and define its relationship with aneurysm behavior. Patients with intracranial aneurysms who were prospectively evaluated using HRMRI between July 2013 and June 2014 were enrolled in this study. The aneurysm's wall enhancement and evidence of inflammation invasion were determined. In addition, the relationship between aneurysm wall enhancement and aneurysm size and symptoms, including ruptured aneurysms, giant unruputred intracranial aneurysms (UIAs) presenting as mass effect, progressively growing aneurysms, and aneurysms associated with neurological symptoms, was statistically analyzed. Twenty-five patients with 30 aneurysms were available for the current study. Fourteen aneurysms showed wall enhancement, including 6 ruptured and 8 unruptured aneurysms. Evidence of inflammation was identified directly through histological studies and indirectly through intraoperative investigations and clinical courses. The statistical analysis indicated no significant correlation between aneurysm wall enhancement and aneurysm size. However, there was a strong correlation between wall enhancement and aneurysm symptoms, with a kappa value of 0.86 (95 % CI 0.68-1). Aneurysm wall enhancement on HRMRI might be a sign of inflammatory change. Symptomatic aneurysms exhibited wall enhancement on HRMRI. Wall enhancement had a high consistent correlation of symptomatic aneurysms. Therefore, wall enhancement on HRMRI might predict an unsteady state of an intracranial saccular aneurysm.

Update on the prevention of death from ruptured abdominal aortic aneurysm.

PubMed

Jacomelli, Jo; Summers, Lisa; Stevenson, Anne; Lees, Tim; Earnshaw, Jonothan J

2017-09-01

Objectives To monitor the early effect of a national population screening programme for abdominal aortic aneurysm in 65-year-old men. Setting The study used national statistics for death rates from abdominal aortic aneurysm (Office of National Statistics) and hospital admission data in England (Hospital Episode Statistics). Methods Information concerning deaths from abdominal aortic aneurysm (ruptured and non-ruptured) (1999-2014) and hospital admissions for ruptured abdominal aortic aneurysm (2000-2015) was examined. Results The absolute number of deaths from abdominal aortic aneurysm in men and women aged 65 and over has decreased by around 30% from 2001 to 2014, but as the population has increased, the relative reduction was 45.6% and 40.0%, respectively. Some 65% of all abdominal aortic aneurysm deaths are in men aged over 65; women aged 65 and over account for around 31%. Deaths from ruptured abdominal aortic aneurysm in men aged 60-74 (the screened group) appear to be declining at the same rate as in men aged 75 and over. The relative decline in admissions to hospital with ruptured abdominal aortic aneurysm may be greater in men and women aged 60-74 (which contains the screened group of men), than those older, giving the first possible evidence that abdominal aortic aneurysm screening is having an effect. Conclusion The death rate from abdominal aortic aneurysm is declining rapidly in England. There is the first evidence that screening may be contributing to this reduction.

Diagnostic accuracy of physical examination for anterior knee instability: a systematic review.

PubMed

Leblanc, Marie-Claude; Kowalczuk, Marcin; Andruszkiewicz, Nicole; Simunovic, Nicole; Farrokhyar, Forough; Turnbull, Travis Lee; Debski, Richard E; Ayeni, Olufemi R

2015-10-01

Determining diagnostic accuracy of Lachman, pivot shift and anterior drawer tests versus gold standard diagnosis (magnetic resonance imaging or arthroscopy) for anterior cruciate ligament (ACL) insufficiency cases. Secondarily, evaluating effects of: chronicity, partial rupture, awake versus anaesthetized evaluation. Searching MEDLINE, EMBASE and PubMed identified studies on diagnostic accuracy for ACL insufficiency. Studies identification and data extraction were performed in duplicate. Quality assessment used QUADAS tool, and statistical analyses were completed for pooled sensitivity and specificity. Eight studies were included. Given insufficient data, pooled analysis was only possible for sensitivity on Lachman and pivot shift test. During awake evaluation, sensitivity for the Lachman test was 89 % (95 % CI 0.76, 0.98) for all rupture types, 96 % (95 % CI 0.90, 1.00) for complete ruptures and 68 % (95 % CI 0.25, 0.98) for partial ruptures. For pivot shift in awake evaluation, results were 79 % (95 % CI 0.63, 0.91) for all rupture types, 86 % (95 % CI 0.68, 0.99) for complete ruptures and 67 % (95 % CI 0.47, 0.83) for partial ruptures. Decreased sensitivity of Lachman and pivot shift tests for partial rupture cases and for awake patients raised suspicions regarding the accuracy of these tests for diagnosis of ACL insufficiency. This may lead to further research aiming to improve the understanding of the true accuracy of these physical diagnostic tests and increase the reliability of clinical investigation for this pathology. IV.

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.

Neurofibromatosis Type 1: Transcatheter Arterial Embolization for Ruptured Occipital Arterial Aneurysms

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

Kanematsu, Masayuki; Kato, Hiroki; Kondo, Hiroshi

Two cases of ruptured aneurysms in the posterior cervical regions associated with type-1 neurofibromatosis treated by transcatheter embolization are reported. Patients presented with acute onset of swelling and pain in the affected areas. Emergently performed contrast-enhanced CT demonstrated aneurysms and large hematomas widespread in the posterior cervical regions. Angiography revealed aneurysms and extravasations of the occipital artery. Patients were successfully treated by percutaneous transcatheter arterial microcoil embolization. Transcatheter arterial embolization therapy was found to be an effective method for treating aneurysmal rupture in the posterior cervical regions occurring in association with type-1 neurofibromatosis. A literature review revealed that rupture ofmore » an occipital arterial aneurysm, in the setting of neurofibromatosis type 1, has not been reported previously.« less

77 FR 24585 - Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-25

... certain power turbine (PT) blade fir-tree roots. This AD requires removing the affected PT blades from... geometric non- conformities on PT blade fir-tree roots. We are issuing this AD to prevent PT blade rupture...

Parent artery occlusion for ruptured “true” posterior communicating artery aneurysm

PubMed Central

Takeda, Nobuaki; Oishi, Hidenori; Arai, Hajime

2015-01-01

A case of a patient with a ruptured true posterior communicating artery (PCoA) aneurysm is reported, who had been managed by early endovascular parent artery occlusion with coils. The small blister aneurysm was located at the proximal PCoA itself and directed superiorly. Postoperative course was uneventful. During 1-month follow-up, the patient recovered well and could care for herself. Aneurysms of the PCoA itself are very rare. As reported to date, surgical procedures would favor microsurgical clipping over endovascular coil embolization. Endovascular treatment may be a good alternative to surgical trapping for true PCoA blister aneurysm. PMID:25953771

Evaluation of an advanced directionally solidified gamma/gamma'-alpha Mo eutectic alloy

NASA Technical Reports Server (NTRS)

Henry, M. F.; Jackson, M. R.; Gigliotti, M. F. X.; Nelson, P. B.

1979-01-01

An attempt was made to improve on the properties of the candidate jet engine turbine blade material AG-60, a gamma/gamma prime-alpha Mo eutectic composite. Alloy 38 (AG-170) was evaluated in the greatest detail. This alloy, Ni-5.88 A1-29.74 Mo-1.65 V-1.2C Re (weight percent), represents an improvement beyond AG-60, based on mechanical testing of the transverse and/or longitudinal orientations over a range of temperatures in tension, shear, rupture, and rupture after thermal exposure. It is likely that other alloys in the study represent a similar improvement.

Structural and stratigraphic constraints on tsunamigenic rupture along the frontal Sunda megathrust from MegaTera bathymetric and seismic reflection data

NASA Astrophysics Data System (ADS)

Bradley, K. E.; Qin, Y.; Villanueva-Robles, F.; Hananto, N.; Leclerc, F.; Singh, S. C.; Tapponnier, P.; Sieh, K.; Wei, S.; Carton, H. D.; Permana, H.; Avianto, P.; Nugroho, A. B.

2017-12-01

The joint EOS/IPG/LIPI 2015 MegaTera expedition collected high-resolution seismic reflection profiles and bathymetric data across the Sunda trench, updip of the Mw7.7, 2010 Mentawai tsunami-earthquake rupture patch. These data reveal rapid lateral variations in both the stratigraphic level of the frontal Sunda megathrust and the vergence of frontal ramp faults. The stratigraphic depth of the megathrust at the deformation front correlates with ramp-thrust vergence and with changes in the basal friction angle inferred by critical-taper wedge theory. Where ramp thrusts verge uniformly seaward and have an average dip of 30°, the megathrust decollement resides atop a high-amplitude reflector that marks the inferred top of pelagic sediments. Where ramp thrusts are bi-vergent (similar throw on both landward- and seaward-vergent faults) and have an average dip of 42°, the decollement is higher, within the incoming clastic sequence, above a seismically transparent unit inferred to represent distal fan muds. Where ramp thrusts are uniformly landward vergent, the decollement sits directly on top of the oceanic crust that forms the bathymetrically prominent, subducting Investigator Ridge. The two, separate regions of large tsunamigenic ground-surface uplift during the 2010 tsunami earthquake that have been inferred from joint inversions of seismic, GPS, and tsunami data (e.g. Yue et al., 2014; Satake et al., 2013) correspond to the areas of frontal bi-vergence in the MegaTera data. We propose that enhanced surface uplift and tsunamigenesis during this event occurred when rupture propagated onto areas where the decollement sits directly above the basal muds of the incoming clastic sequence. Thus we hypothesize that frontal bi-vergence may mark areas of enhanced tsunami hazard posed by small magnitude, shallow megathrust ruptures that propagate to the trench. [Yue, H. et al., 2014, Rupture process of the…, JGR 119 doi:10.1002/2014JB011082; Satake, K. et al., 2013, Tsunami Source of the…, P&AG 170, 9-10

Micromechanical models to guide the development of synthetic ‘brick and mortar’ composites

NASA Astrophysics Data System (ADS)

Begley, Matthew R.; Philips, Noah R.; Compton, Brett G.; Wilbrink, David V.; Ritchie, Robert O.; Utz, Marcel

2012-08-01

This paper describes a micromechanical analysis of the uniaxial response of composites comprising elastic platelets (bricks) bonded together with thin elastic perfectly plastic layers (mortar). The model yields closed-form results for the spatial variation of displacements in the bricks as a function of constituent properties, which can be used to calculate the effective properties of the composite, including elastic modulus, strength and work-to-failure. Regime maps are presented which indicate critical stresses for failure of the bricks and mortar as a function of constituent properties and brick architecture. The solution illustrates trade-offs between elastic modulus, strength and dissipated work that are a result of transitions between various failure mechanisms associated with brick rupture and rupture of the interfaces. Detailed scaling relationships are presented with the goal of providing material developers with a straightforward means to identify synthesis targets that balance competing mechanical behaviors and optimize material response. Ashby maps are presented to compare potential brick and mortar composites with existing materials, and identify future directions for material development.

Oil Motion Control by an Extra Pinning Structure in Electro-Fluidic Display.

PubMed

Dou, Yingying; Tang, Biao; Groenewold, Jan; Li, Fahong; Yue, Qiao; Zhou, Rui; Li, Hui; Shui, Lingling; Henzen, Alex; Zhou, Guofu

2018-04-06

Oil motion control is the key for the optical performance of electro-fluidic displays (EFD). In this paper, we introduced an extra pinning structure (EPS) into the EFD pixel to control the oil motion inside for the first time. The pinning structure canbe fabricated together with the pixel wall by a one-step lithography process. The effect of the relative location of the EPS in pixels on the oil motion was studied by a series of optoelectronic measurements. EPS showed good control of oil rupture position. The properly located EPS effectively guided the oil contraction direction, significantly accelerated switching on process, and suppressed oil overflow, without declining in aperture ratio. An asymmetrically designed EPS off the diagonal is recommended. This study provides a novel and facile way for oil motion control within an EFD pixel in both direction and timescale.

Anisotropic toughness and strength in graphene and its atomistic origin

NASA Astrophysics Data System (ADS)

Hossain, M. Zubaer; Ahmed, Tousif; Silverman, Benjamin; Khawaja, M. Shehroz; Calderon, Justice; Rutten, Andrew; Tse, Stanley

2018-01-01

This paper presents the implication of crystallographic orientation on toughness and ideal strength in graphene under lattice symmetry-preserving and symmetry-breaking deformations. In symmetry-preserving deformation, both toughness and strength are isotropic, regardless of the chirality of the lattice; whereas, in symmetry-breaking deformation they are strongly anisotropic, even in the presence of vacancy defects. The maximum and minimum of toughness or strength occur for loading along the zigzag direction and the armchair direction, respectively. The anisotropic behavior is governed by a complex interplay among bond-stretching deformation, bond-bending deformation, and the chirality of the lattice. Nevertheless, the condition for crack-nucleation is dictated by the maximum bond-force required for bond rupture, and it is independent of the chiral angle of the lattice or loading direction. At the onset of crack-nucleation a localized nucleation zone is formed, wherein the bonds rupture locally satisfying the maximum bond-force criterion. The nucleation zone acts as the physical origin in triggering the fracture nucleation process, but its presence is undetectable from the macroscopic stress-strain data.

Prophylactic transabdominal amnioinfusion in oligohydramnios for preterm premature rupture of membranes: increase of amniotic fluid index during latency period.

PubMed

Garzetti, G G; Ciavattini, A; De Cristofaro, F; La Marca, N; Arduini, D

1997-01-01

This study was designed to: (i) evaluate the effect of amnioinfusion on the latency period in patients with oligohydramnios for preterm premature rupture of membranes, and (ii) to investigate the relationship between changes in the amniotic fluid index and fetal heart rate short-term variability by computerized Hewlett-Packard cardiotocography, longitudinally estimated before and after prophylactic amnioinfusion. All singleton pregnancies with prolonged premature rupture of membranes after 25 weeks of gestation and seen at the Institute of Obstetrics and Gynecology, University of Ancona (Italy), between January 1994 and June 1995 were included in the study. Transabdominal amnioinfusion with 150-350 ml warmed normal saline (25-50 ml/min) was performed at weekly intervals. Amniotic fluid volume was assessed ultrasonographically by means of the four-quadrant technique on a weekly basis before and after each amnioinfusion, as well as the short-term variability by a Hewlett-Packard computerized cardiotocographic system. 18 women were enrolled and underwent prophylactic transabdominal amnioinfusion at weekly intervals until delivery. Eighteen controls, who did not undergo prophylactic amnioinfusion, were recruited from our 1992-1993 series and included in the study. The median interval between premature rupture of membranes and delivery was 3.0 weeks (range 1-8 weeks), with an average delivery age of 33.0 weeks (range 27-36 weeks). The latency period was significantly longer in patients who underwent prophylactic amnioinfusion (mean +/- SD, 4.1 +/- 1.7 weeks) than in controls(1.7 +/- 1.0 weeks; p < 0.001). An increase in both the weekly amniotic fluid index (linear regression analysis r = 0.8, p = 0.03) and the weekly short-term variability (linear regression analysis r = 0.82, p = 0.02) was observed among patients who underwent prophylactic amnioinfusion. A direct relationship was observed between the amniotic fluid index and short-term variability (linear regression analysis r = 0.54, p = 0.04). The mean values of fetal movements recorded by computerized tomography during the 20 min of observation significantly increased after amnioinfusion in comparison with those before it (2.6 +/- 0.9 and 0.9 +/- 0.7 respectively; p = 0.001). The present study has shown a positive effect of prophylactic transabdominal amnioinfusion on the latency period in patients with preterm premature rupture of membranes and oligohydramnios. Among the patients who underwent amnioinfusion, an interesting improvement in fetal heart rate short-term variability was associated with the progressive increase in amniotic fluid volume, as an expression of fetal well-being.

Probabilistic seismic hazard in the San Francisco Bay area based on a simplified viscoelastic cycle model of fault interactions

USGS Publications Warehouse

Pollitz, F.F.; Schwartz, D.P.

2008-01-01

We construct a viscoelastic cycle model of plate boundary deformation that includes the effect of time-dependent interseismic strain accumulation, coseismic strain release, and viscoelastic relaxation of the substrate beneath the seismogenic crust. For a given fault system, time-averaged stress changes at any point (not on a fault) are constrained to zero; that is, kinematic consistency is enforced for the fault system. The dates of last rupture, mean recurrence times, and the slip distributions of the (assumed) repeating ruptures are key inputs into the viscoelastic cycle model. This simple formulation allows construction of stress evolution at all points in the plate boundary zone for purposes of probabilistic seismic hazard analysis (PSHA). Stress evolution is combined with a Coulomb failure stress threshold at representative points on the fault segments to estimate the times of their respective future ruptures. In our PSHA we consider uncertainties in a four-dimensional parameter space: the rupture peridocities, slip distributions, time of last earthquake (for prehistoric ruptures) and Coulomb failure stress thresholds. We apply this methodology to the San Francisco Bay region using a recently determined fault chronology of area faults. Assuming single-segment rupture scenarios, we find that fature rupture probabilities of area faults in the coming decades are the highest for the southern Hayward, Rodgers Creek, and northern Calaveras faults. This conclusion is qualitatively similar to that of Working Group on California Earthquake Probabilities, but the probabilities derived here are significantly higher. Given that fault rupture probabilities are highly model-dependent, no single model should be used to assess to time-dependent rupture probabilities. We suggest that several models, including the present one, be used in a comprehensive PSHA methodology, as was done by Working Group on California Earthquake Probabilities.

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.

Delineation of Rupture Propagation of Large Earthquakes Using Source-Scanning Algorithm: A Control Study

NASA Astrophysics Data System (ADS)

Kao, H.; Shan, S.

2004-12-01

Determination of the rupture propagation of large earthquakes is important and of wide interest to the seismological research community. The conventional inversion method determines the distribution of slip at a grid of subfaults whose orientations are predefined. As a result, difference choices of fault geometry and dimensions often result in different solutions. In this study, we try to reconstruct the rupture history of an earthquake using the newly developed Source-Scanning Algorithm (SSA) without imposing any a priori constraints on the fault's orientation and dimension. The SSA identifies the distribution of seismic sources in two steps. First, it calculates the theoretical arrival times from all grid points inside the model space to all seismic stations by assuming an origin time. Then, the absolute amplitudes of the observed waveforms at the predicted arrival times are added to give the "brightness" of each time-space pair, and the brightest spots mark the locations of sources. The propagation of the rupture is depicted by the migration of the brightest spots throughout a prescribed time window. A series of experiments are conducted to test the resolution of the SSA inversion. Contrary to the conventional wisdom that seismometers should be placed as close as possible to the fault trace to give the best resolution in delineating rupture details, we found that the best results are obtained if the seismograms are recorded at a distance about half of the total rupture length away from the fault trace. This is especially true when the rupture duration is longer than ~10 s. A possible explanation is that the geometric spreading effects for waveforms from different segments of the rupture are about the same if the stations are sufficiently away from the fault trace, thus giving a uniform resolution to the entire rupture history.

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.

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.

Failure of antioxidants to protect against angiotensin II-induced aortic rupture in aged apolipoprotein(E)-deficient mice.

PubMed

Jiang, F; Jones, G T; Dusting, G J

2007-11-01

Oxidative stress may be involved in the development of abdominal aortic aneurysms (AAAs). Previous studies indicate that antioxidants protect against AAA formation during chronic angiotensin (Ang) II infusion in apolipoprotein E-deficient (ApoE(0)) mice. We here examine if these protective effects also occurred in aged ApoE(0) mice. Male ApoE(0) mice (50-60 weeks) were randomly divided into 4 groups: saline, Ang II (1000 ng kg(-1) min(-1) for 4 weeks), Ang II plus antioxidants (0.1% vitamin E in food plus 0.1% vitamin C in drinking water), and Ang II plus losartan (30 mg kg(-1) day(-1)). Exogenous Ang II increased systolic blood pressure by 40 mmHg and resulted in the formation of pseudoaneurysms (rupture and extramural haematoma) in the abdominal aorta in 50% of animals. True aneurysmal dilatation was rarely observed. Antioxidants decreased systemic oxidative stress (plasma malondialdehyde), but had only minor effects on aortic rupture, relative to the complete prevention by losartan. Immunohistochemistry revealed strong matrix metalloproteinase-9 (MMP-9) expression in atherosclerotic plaques and at the sites of rupture. Antioxidants did not affect tumour necrosis factor-alpha-stimulated MMP-9 release from U937 cells. In addition, antioxidants had little effects on Ang II-induced renal dysfunction. In contrast to previous findings in younger mice, antioxidants had only minor effects on Ang II-induced aortic rupture in aged mice. Our results demonstrate that the pathological features of the aneurysmal remodelling induced by Ang II in old ApoE(0) mice are distinct from those of human AAA.

Analyzing Single-Event Gate Ruptures In Power MOSFET's

NASA Technical Reports Server (NTRS)

Zoutendyk, John A.

1993-01-01

Susceptibilities of power metal-oxide/semiconductor field-effect transistors (MOSFET's) to single-event gate ruptures analyzed by exposing devices to beams of energetic bromine ions while applying appropriate bias voltages to source, gate, and drain terminals and measuring current flowing into or out of each terminal.

Large Steel Tank Fails and Rockets to Height of 30 meters - Rupture Disc Installed Incorrectly.

PubMed

Hedlund, Frank H; Selig, Robert S; Kragh, Eva K

2016-06-01

At a brewery, the base plate-to-shell weld seam of a 90-m(3) vertical cylindrical steel tank failed catastrophically. The 4 ton tank "took off" like a rocket leaving its contents behind, and landed on a van, crushing it. The top of the tank reached a height of 30 m. The internal overpressure responsible for the failure was an estimated 60 kPa. A rupture disc rated at < 50 kPa provided overpressure protection and thus prevented the tank from being covered by the European Pressure Equipment Directive. This safeguard failed and it was later discovered that the rupture disc had been installed upside down. The organizational root cause of this incident may be a fundamental lack of appreciation of the hazards of large volumes of low-pressure compressed air or gas. A contributing factor may be that the standard piping and instrumentation diagram (P&ID) symbol for a rupture disc may confuse and lead to incorrect installation. Compressed air systems are ubiquitous. The medium is not toxic or flammable. Such systems however, when operated at "slight overpressure" can store a great deal of energy and thus constitute a hazard that ought to be addressed by safety managers.

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.

In vivo MRI-based simulation of fatigue process: a possible trigger for human carotid atherosclerotic plaque rupture.

PubMed

Huang, Yuan; Teng, Zhongzhao; Sadat, Umar; He, Jing; Graves, Martin J; Gillard, Jonathan H

2013-04-23

Atherosclerotic plaque is subjected to a repetitive deformation due to arterial pulsatility during each cardiac cycle and damage may be accumulated over a time period causing fibrous cap (FC) fatigue, which may ultimately lead to rupture. In this study, we investigate the fatigue process in human carotid plaques using in vivo carotid magnetic resonance (MR) imaging. Twenty seven patients with atherosclerotic carotid artery disease were included in this study. Multi-sequence, high-resolution MR imaging was performed to depict the plaque structure. Twenty patients were found with ruptured FC or ulceration and 7 without. Modified Paris law was used to govern crack propagation and the propagation direction was perpendicular to the maximum principal stress at the element node located at the vulnerable site. The predicted crack initiations from 20 patients with FC defect all matched with the locations of the in vivo observed FC defect. Crack length increased rapidly with numerical steps. The natural logarithm of fatigue life decreased linearly with the local FC thickness (R(2) = 0.67). Plaques (n=7) without FC defect had a longer fatigue life compared with those with FC defect (p = 0.03). Fatigue process seems to explain the development of cracks in FC, which ultimately lead to plaque rupture.

The 2015 M w 6.0 Mt. Kinabalu earthquake: an infrequent fault rupture within the Crocker fault system of East Malaysia

NASA Astrophysics Data System (ADS)

Wang, Yu; Wei, Shengji; Wang, Xin; Lindsey, Eric O.; Tongkul, Felix; Tapponnier, Paul; Bradley, Kyle; Chan, Chung-Han; Hill, Emma M.; Sieh, Kerry

2017-12-01

The M w 6.0 Mt. Kinabalu earthquake of 2015 was a complete (and deadly) surprise, because it occurred well away from the nearest plate boundary in a region of very low historical seismicity. Our seismological, space geodetic, geomorphological, and field investigations show that the earthquake resulted from rupture of a northwest-dipping normal fault that did not reach the surface. Its unilateral rupture was almost directly beneath 4000-m-high Mt. Kinabalu and triggered widespread slope failures on steep mountainous slopes, which included rockfalls that killed 18 hikers. Our seismological and morphotectonic analyses suggest that the rupture occurred on a normal fault that splays upwards off of the previously identified normal Marakau fault. Our mapping of tectonic landforms reveals that these faults are part of a 200-km-long system of normal faults that traverse the eastern side of the Crocker Range, parallel to Sabah's northwestern coastline. Although the tectonic reason for this active normal fault system remains unclear, the lengths of the longest fault segments suggest that they are capable of generating magnitude 7 earthquakes. Such large earthquakes must occur very rarely, though, given the hitherto undetectable geodetic rates of active tectonic deformation across the region.

Rupture luminescence from natural fibers

NASA Astrophysics Data System (ADS)

Li, W.; Haneman, D.

1999-12-01

Fibers of cotton and wool, and samples of paper, have been ruptured in tension in vacuum and in air, and give detectable luminescence in the visible range. All have a common emission peak at around 2.0 eV, which is ascribed to the deexcitation of states excited by the rupture of organic chain molecule bonds. Rubber bands give stronger emission in air, but no emission in vacuum, suggesting the material breaks only at weak interchain bonds. Mohair, cat, and horse hair also give emission in air. The phenomena reveal effects that would occur widely in nature.

Antihyperglycemic Agents Are Inversely Associated With Intracranial Aneurysm Rupture.

PubMed

Can, Anil; Castro, Victor M; Yu, Sheng; Dligach, Dmitriy; Finan, Sean; Gainer, Vivian S; Shadick, Nancy A; Savova, Guergana; Murphy, Shawn; Cai, Tianxi; Weiss, Scott T; Du, Rose

2018-01-01

Previous studies have suggested a protective effect of diabetes mellitus on aneurysmal subarachnoid hemorrhage risk. However, reports are inconsistent, and objective measures of hyperglycemia in these studies are lacking. Our aim was to investigate the association between aneurysmal subarachnoid hemorrhage and antihyperglycemic agent use and glycated hemoglobin levels. The medical records of 4701 patients with 6411 intracranial aneurysms, including 1201 prospective patients, diagnosed at the Massachusetts General Hospital and Brigham and Women's Hospital between 1990 and 2016 were reviewed and analyzed. Patients were separated into ruptured and nonruptured groups. Univariate and multivariate logistic regression analyses were performed to determine the association between aneurysmal subarachnoid hemorrhage and antihyperglycemic agents and glycated hemoglobin levels. Propensity score weighting was used to account for selection bias. In both unweighted and weighted multivariate analysis, antihyperglycemic agent use was inversely and significantly associated with ruptured aneurysms (unweighted odds ratio, 0.58; 95% confidence interval, 0.39-0.87; weighted odds ratio, 0.57; 95% confidence interval, 0.34-0.96). In contrast, glycated hemoglobin levels were not significantly associated with rupture status. Antihyperglycemic agent use rather than hyperglycemia is associated with decreased risk of aneurysmal subarachnoid hemorrhage, suggesting a possible protective effect of glucose-lowering agents in the pathogenesis of aneurysm rupture. © 2017 American Heart Association, Inc.

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.

The Siesta Habit is Associated with a Decreased Risk of Rupture of Intracranial Aneurysms.

PubMed

Kang, Huibin; Feng, Xin; Zhang, Baorui; Guo, Erkang; Wang, Luyao; Qian, Zenghui; Liu, Peng; Wen, Xiaolong; Xu, Wenjuan; Li, Youxiang; Jiang, Chuhan; Wu, Zhongxue; Zhang, Hongbing; Liu, Aihua

2017-01-01

Previous studies have examined an association between the siesta habit and hypertension, as well as coronary heart disease. However, the relationship between a siesta and the risk of rupture of an intracranial aneurysm (IA) has not yet been established. We aimed to investigate the effects of a siesta on the risk of rupture of IAs. We prospectively enrolled consecutive patients diagnosed with IAs at our hospital between January 2016 and December 2016. Univariate and multivariate logistic regression analysis were performed to identify independent risk factors associated with IA rupture. We studied 581 consecutive patients with 514 unruptured and 120 ruptured aneurysms. Univariate analysis demonstrated that hypertension, hyperlipidemia, diabetes mellitus, cigarette smoking, location, size, as well as shape and aspect ratio were associated with the risk of rupture of IAs. Multivariate analysis identified hypertension [odds ratio (OR) 1.68, 95% confidence interval (CI) 1.03-2.73], hyperlipidemia (OR 0.25, 95% CI 0.08-0.72), current cigarette smoking ≥20 cigarettes/day (d) (OR 3.48, 95% CI 1.63-7.47), siesta (siesta time <1 h, OR 0.49, 95% CI 0.24-0.98 and siesta time ≥1 h, OR 0.32, 95% CI 0.19-0.57), location of largest aneurysm on the anterior communicating and internal carotid-posterior communicating artery (PCOM) (anterior communicating artery OR 16.27, 95% CI 7.40-35.79 and PCOM OR 11.21, 95% CI 5.15-24.43), and size of aneurysm ≥7 mm (OR 2.19, 95% CI 1.21-3.97) as independent strong risk factors associated with risk of aneurysm rupture. In the present study, we found that a habitual siesta is a new predictive factor to assess the risk of rupture of an IA. We found the siesta habit may reduce the risk of aneurysm rupture. We also found that hypertension, hyperlipidemia, cigarette smoking, location, and size of aneurysm were associated with the risk of rupture of IAs.

Modeling of the strong ground motion of 25th April 2015 Nepal earthquake using modified semi-empirical technique

NASA Astrophysics Data System (ADS)

Lal, Sohan; Joshi, A.; Sandeep; Tomer, Monu; Kumar, Parveen; Kuo, Chun-Hsiang; Lin, Che-Min; Wen, Kuo-Liang; Sharma, M. L.

2018-05-01

On 25th April, 2015 a hazardous earthquake of moment magnitude 7.9 occurred in Nepal. Accelerographs were used to record the Nepal earthquake which is installed in the Kumaon region in the Himalayan state of Uttrakhand. The distance of the recorded stations in the Kumaon region from the epicenter of the earthquake is about 420-515 km. Modified semi-empirical technique of modeling finite faults has been used in this paper to simulate strong earthquake at these stations. Source parameters of the Nepal aftershock have been also calculated using the Brune model in the present study which are used in the modeling of the Nepal main shock. The obtained value of the seismic moment and stress drop is 8.26 × 1025 dyn cm and 10.48 bar, respectively, for the aftershock from the Brune model .The simulated earthquake time series were compared with the observed records of the earthquake. The comparison of full waveform and its response spectra has been made to finalize the rupture parameters and its location. The rupture of the earthquake was propagated in the NE-SW direction from the hypocenter with the rupture velocity 3.0 km/s from a distance of 80 km from Kathmandu in NW direction at a depth of 12 km as per compared results.

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

Ar Latin-Small-Letter-Dotless-I bas, Bilgin Kadri, E-mail: bilginaribas@hotmail.com; Dingil, Guerbuez; Koeroglu, Mert

The aim of this case study is to present effectiveness of percutaneous drainage as a treatment option of ruptured lung and liver hydatid cysts. A 65-year-old male patient was admitted with complicated liver and lung hydatid cysts. A liver hydatid cyst had ruptured transdiaphragmatically, and a lung hydatid cyst had ruptured both into bronchi and pleural space. The patient could not undergo surgery because of decreased respiratory function. Both cysts were drained percutaneously using oral albendazole. Povidone-iodine was used to treat the liver cyst after closure of the diaphragmatic rupture. The drainage was considered successful, and the patient had nomore » recurrence of signs and symptoms. Clinical, laboratory, and radiologic recovery was observed during 2.5 months of catheterization. The patient was asymptomatic after catheter drainage. No recurrence was detected during 86 months of follow-up. For inoperable patients with ruptured liver and lung hydatid cysts, percutaneous drainage with oral albendazole is an alternative treatment option to surgery. The percutaneous approach can be life-saving in such cases.« less

Functional management of Achilles tendon rupture: A viable option for non-operative management.

PubMed

Karkhanis, S; Mumtaz, H; Kurdy, N

2010-06-01

Functional management of the ruptured Achilles tendon can be effective using orthoses like the removable walker boot (Foam Walker Boot, Air Cast UK Limited, Lincolnshire, United Kingdom). We conducted this study to look at the outcome of our protocol using this orthosis. We retrospectively reviewed 107 non-operatively managed Achilles tendon ruptures over the last 5 years. Case notes were analyzed for demographics and immediate outcomes. Long term outcomes were assessed by a postal questionnaire using the Achilles Tendon Total Rupture Score (ATRS). Of the 107 tendons (male:female=71:36, mean age=50 years), 105 tendons (98%) healed with an average discharge time of 22 weeks. Six patients reported major complications and 6 reported minor complications. We received 56 questionnaires with a mean ATRS score of 21. Seventy-seven percent returned to pre-injury level of activity. Functional management of Achilles tendon rupture, under appropriate supervision, provides a viable option for non-operative management. Copyright 2009 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

The 2014 update to the National Seismic Hazard Model in California

USGS Publications Warehouse

Powers, Peter; Field, Edward H.

2015-01-01

The 2014 update to the U. S. Geological Survey National Seismic Hazard Model in California introduces a new earthquake rate model and new ground motion models (GMMs) that give rise to numerous changes to seismic hazard throughout the state. The updated earthquake rate model is the third version of the Uniform California Earthquake Rupture Forecast (UCERF3), wherein the rates of all ruptures are determined via a self-consistent inverse methodology. This approach accommodates multifault ruptures and reduces the overprediction of moderate earthquake rates exhibited by the previous model (UCERF2). UCERF3 introduces new faults, changes to slip or moment rates on existing faults, and adaptively smoothed gridded seismicity source models, all of which contribute to significant changes in hazard. New GMMs increase ground motion near large strike-slip faults and reduce hazard over dip-slip faults. The addition of very large strike-slip ruptures and decreased reverse fault rupture rates in UCERF3 further enhances these effects.

Effect of Environment on Stress-Rupture Behavior of a Carbon Fiber-Reinforced Silicon Carbide (C/SiC) Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Opila, Elizabeth J.; Calomino, Anthony; Kiser, J. Douglas

2002-01-01

Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C. Stress-rupture lives in air and steam containing environments (50 - 80% steam with argon) are similar for a composite stress of 69 MPa at 1200 C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600 C, composite life in 20% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.

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.

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.

Mitral valve repair using ePTFE sutures for ruptured mitral chordae tendineae: a computational simulation study.

PubMed

Rim, Yonghoon; Laing, Susan T; McPherson, David D; Kim, Hyunggun

2014-01-01

Mitral valve (MV) repair using expanded polytetrafluoroethylene sutures is an established and preferred interventional method to resolve the complex pathophysiologic problems associated with chordal rupture. We developed a novel computational evaluation protocol to determine the effect of the artificial sutures on restoring MV function following valve repair. A virtual MV was created using three-dimensional echocardiographic data in a patient with ruptured mitral chordae tendineae (RMCT). Virtual repairs were designed by adding artificial sutures between the papillary muscles and the posterior leaflet where the native chordae were ruptured. Dynamic finite element simulations were performed to evaluate pre- and post-repair MV function. Abnormal posterior leaflet prolapse and mitral regurgitation was clearly demonstrated in the MV with ruptured chordae. Following virtual repair to reconstruct ruptured chordae, the severity of the posterior leaflet prolapse decreased and stress concentration was markedly reduced both in the leaflet tissue and the intact native chordae. Complete leaflet coaptation was restored when four or six sutures were utilized. Computational simulations provided quantitative information of functional improvement following MV repair. This novel simulation strategy may provide a powerful tool for evaluation and prediction of interventional treatment for RMCT.

Remote Imaging of Earthquake Characteristics Along Oceanic Transforms

NASA Astrophysics Data System (ADS)

Cleveland, M.; Ammon, C. J.

2014-12-01

Compared with subduction and continental transform systems, many characteristics of oceanic transform faults (OTF) are better defined (first-order structure and composition, thermal properties, etc.). Still, many aspects of earthquake behavior along OTFs remain poorly understood as a result of their relative remoteness. But the substantial aseismic deformation (averaging roughly 85%) that occurs along OTFs and the implied interaction of aseismic with seismic deformation is an opportunity to explore fundamental earthquake nucleation and rupture processes. However, the study of OTF earthquake properties is not easy because these faults are often located in remote regions, lacking nearby seismic networks. Thus, many standard network-based seismic approaches are infeasible, but some can be adapted to the effort. For example, double-difference methods applied to cross-correlation measured Rayleigh wave time shifts is an effective tool to provide greatly improved relative epicentroid locations, origin-time shifts, and relative event magnitudes for earthquakes in remote regions. The same comparative waveform measurements can provide insight into rupture directivity of the larger OTF events. In this study, we calculate improved relative earthquake locations and magnitudes of earthquakes along the Blanco Fracture Zone in the northeast Pacific Ocean and compare and contrast that work with a study of the more remote Menard Transform Fault (MTF), located in the southeast Pacific Ocean. For the Blanco, we work exclusively with Rayleigh (R1) observations exploiting the dense networks in the northern hemisphere. For the MTF, we combine R1 with Love (G1) observations to map and to analyze the distribution of strong asperities along this remote, 200-km-long fault. Specifically, we attempt to better define the relationship between observed near-transform normal and vertical strike-slip earthquakes in the vicinity of the MTF. We test our ability to use distant observations (the closest station is about 2,500 km distant) to constrain rupture characteristics of recent strong earthquakes in the region. We compare the seismicity characteristics along the faults to explore the relationship of fault age and morphology on rupture behavior.

Seafloor seismological/geodetic observations in the rupture area of the 2011 Tohoku-oki Earthquake

NASA Astrophysics Data System (ADS)

Hino, Ryota; Shinohara, Masanao; Ito, Yoshihiro

2016-04-01

A number of important aspects of the 2011 Tohoku-oki earthquake (Mw 9.0) were clarified by the seafloor seismological and geodetic observation above the rupture area of the earthquake. Besides the extraordinarily large coseismic displacements, various kinds of slow slip phenomena associated with intensive micro-seismicity on the plate boundary fault were identified by near field ocean bottom seismographs and seafloor geodetic observation networks. The Tohoku-oki earthquake was preceded by evident foreshock activity with a spatial expansion of this seismicity. The activity became significantly intense after the occurrence of the largest foreshock two days before the mainshock rupture. During the period, clear continuous seafloor deformation was identified caused by the aseismic slip following the largest foreshock. Another different type of aseismic slip event had occurred before this pre-imminent activity had started about a month before the largest foreshock happened. The observed increased seismicity associated with aseismic slip suggests that there must have been some chain reaction like interplay of seismic and interseismic slips before the large earthquake broke out. However, no evident deformation signals were observed indicating acceleration of fault slip immediately before the mainshock. Seafloor geodetic measurements reveals that the postseismic deformation around the rupture area of the Tohoku-oki earthquake shows complex spatial pattern and the complexity is mostly due to significant viscoelastic relaxation induced by the huge coseismic slip. The effects of viscoelastic deformation makes it difficult to identify the deformation associated with the after slip or regaining of interplate coupling and requires us to enhance the abilities of seafloor monitoring to detect the slip activities on the fault. We started an array of seismometer arrays observation including broad-band seismographs to detect and locate slow-slip events and low-frequency tremors. Another observation we started is direct-path acoustic ranging across the trench axis. Slip rate of the shallow fault can be measured by monitoring the change in distance between the benchmarks on the incoming and overrding plates.

How material contrast around subduction faults may control coseismic slip and rupture dynamics: tsunami applications for the case study of Tohoku

NASA Astrophysics Data System (ADS)

Scala, Antonio; Murphy, Shane; Romano, Fabrizio; Lorito, Stefano; Festa, Gaetano; Volpe, Manuela; Piatanesi, Alessio

2017-04-01

Recent megathrust tsunamigenic events, e.g. Maule 2010 (M8.8) and Tohoku 2011 (M9.0), generated huge tsunami waves as a consequence of high slip in the shallow part of the respective subduction zone. Other events, (e.g. the recent Mentawai 2010, M7.8, or the historical Meiji 1896, M8.2), referred to as tsunami earthquakes, produced unexpectedly large tsunami waves, probably due to large slip at shallow depth over longer rupture durations compared to deeper thrust events. Subduction zone earthquakes originate and propagate along bimaterial interfaces separating materials having different elastic properties, e.g. continental and oceanic crust, a stiffer deep mantle wedge, shallow compliant accretionary prism etc. Bimaterial interfaces have been showed, through observations (seismological and laboratory) and theoretical studies, to affect the rupture: introducing a preferred rupture direction as well as asymmetric rupture velocities and shear stress redistributions. Such features are predominantly due to the break of symmetry between the two sides of the interface in turn ascribable to the complex coupling between the frictional interfacial sliding and the slip-induced normal stress perturbations. In order to examine the influence of material contrast on a fault plane on the seismic source and tsunami waves, we modelled a Tohoku-like subduction zone to perform a large number of 2D along-dip rupture dynamics simulations in the framework of linear slip weakening both for homogeneous and bimaterial fault. In this latter model, the rupture acts as the interface between the subducting oceanic crust and the overriding layers (accretionary prism, continental crust and mantle wedge), varying the position of the shear stress asperity acting as nucleation patch. Initial results reveal that ruptures in homogeneous media produce earthquakes with large slip at depth compared to the case where bi-material interface is included. However the opposite occurs for events nucleating at intermediate depths: the compliant accretionary prism favours slip up to the free surface leading to larger events compared to the homogeneous case. These preliminary findings will be further investigated considering different material contrasts between the slab and the overriding accretionary prism to mimic the slowness of the sedimentary wedge. This will contribute to assess the influence of these contrasts in more realistic environment on the seismic source features and, in turn, on the conditional probability of exceedance for maximum tsunami wave height for a M9 event. Several source parameters, such as coseismic slip, rupture duration, rupture velocity and stress conditions, derived from the numerical simulations will be compared to those inferred from real events using existing finite fault catalogues (e.g. USGS, SRCMOD, etc.).

Nonlinear Inversion for Dynamic Rupture Parameters from the 2004 Mw6.0 Parkfield Earthquake

NASA Astrophysics Data System (ADS)

Jimenez, R. M.; Olsen, K. B.

2007-12-01

The Parkfield section of the San Andreas Fault has produced repeated moderate-size earthquakes at fairly regular intervals and is therefore an important target for investigations of rupture initiation, propagation and arrest, which could eventually lead to clues on earthquake prediction. The most recent member of the Parkfield series of earthquakes, the 2004 Mw6.0 event, produced a considerable amount of high-resolution strong motion data, and provides an ideal test bed for analysis of the dynamic rupture propagation. Here, we use a systematic nonlinear direct-search method to invert strong-ground motion data (less than 1 Hz) at 37 stations to obtain models of the slip weakening distance and spatially-varying stress drop (8 by 4 subfaults) on the (vertical) causative segment of the San Andreas fault (40 km long by 15 km wide), along with spatial-temporal coseismic slip distributions. The rupture and wave propagation modeling is performed by a three-dimensional finite-difference method with a slip- weakening friction law and the stress-glut dynamic-rupture formulation (Andrews, 1999), and the inversion is carried out by a neighborhood algorithm (Sambridge, 1999), minimizing the least-squares misfit between the calculated and observed seismograms. The dynamic rupture is nucleated artificially by lowering the yield stress in a 3 km by 3 km patch centered at the location of the hypocenter estimated from strong motion data. Outside the nucleation patch the yield stress is kept constant (5-10 MPa), and we constrain the slip-weakening distance to values less than 1 m. We compare the inversion results for two different velocity models: (1) a 3-D model based on the P-wave velocity structure by Thurber (2006), with S-wave and density relations based on Brocher (2005), and (2) a combination of two different 1-D layered velocity structures on either side of the fault, as proposed by Liu et al. (2006). Due to the non-uniqueness of the problem, the inversion provides an ensemble of equally valid rupture models that produce synthetics with comparable fit to the observed strong motion data. Our preliminary results with the smallest misfits, out of about 3000 tested rupture models, suggest an average slip-weakening distance of 19-81 cm and an average stress drop across the fault of 6.7 - 8.4 MPa. Compared to the kinematic inversion results by Liu et al. (2006) our models with the smallest misfits produce a larger maximum slip (up to about 81 cm) and smaller rupture area, but similar rupture duration (5-7s). The inversions carried out for the layered models tend to produce smaller misfit between data and synthetics as compared to the results using the 3D structure. This suggests that our 3D structure needs improvement, including the Vs-Vp and density-Vp relation. We expect further decrease in the misfit values by increasing the number of tested rupture models.

Accounting for Fault Roughness in Pseudo-Dynamic Ground-Motion Simulations

NASA Astrophysics Data System (ADS)

Mai, P. Martin; Galis, Martin; Thingbaijam, Kiran K. S.; Vyas, Jagdish C.; Dunham, Eric M.

2017-09-01

Geological faults comprise large-scale segmentation and small-scale roughness. These multi-scale geometrical complexities determine the dynamics of the earthquake rupture process, and therefore affect the radiated seismic wavefield. In this study, we examine how different parameterizations of fault roughness lead to variability in the rupture evolution and the resulting near-fault ground motions. Rupture incoherence naturally induced by fault roughness generates high-frequency radiation that follows an ω-2 decay in displacement amplitude spectra. Because dynamic rupture simulations are computationally expensive, we test several kinematic source approximations designed to emulate the observed dynamic behavior. When simplifying the rough-fault geometry, we find that perturbations in local moment tensor orientation are important, while perturbations in local source location are not. Thus, a planar fault can be assumed if the local strike, dip, and rake are maintained. We observe that dynamic rake angle variations are anti-correlated with the local dip angles. Testing two parameterizations of dynamically consistent Yoffe-type source-time function, we show that the seismic wavefield of the approximated kinematic ruptures well reproduces the radiated seismic waves of the complete dynamic source process. This finding opens a new avenue for an improved pseudo-dynamic source characterization that captures the effects of fault roughness on earthquake rupture evolution. By including also the correlations between kinematic source parameters, we outline a new pseudo-dynamic rupture modeling approach for broadband ground-motion simulation.

Planar seismic source characterization models developed for probabilistic seismic hazard assessment of Istanbul

NASA Astrophysics Data System (ADS)

Gülerce, Zeynep; Buğra Soyman, Kadir; Güner, Barış; Kaymakci, Nuretdin

2017-12-01

This contribution provides an updated planar seismic source characterization (SSC) model to be used in the probabilistic seismic hazard assessment (PSHA) for Istanbul. It defines planar rupture systems for the four main segments of the North Anatolian fault zone (NAFZ) that are critical for the PSHA of Istanbul: segments covering the rupture zones of the 1999 Kocaeli and Düzce earthquakes, central Marmara, and Ganos/Saros segments. In each rupture system, the source geometry is defined in terms of fault length, fault width, fault plane attitude, and segmentation points. Activity rates and the magnitude recurrence models for each rupture system are established by considering geological and geodetic constraints and are tested based on the observed seismicity that is associated with the rupture system. Uncertainty in the SSC model parameters (e.g., b value, maximum magnitude, slip rate, weights of the rupture scenarios) is considered, whereas the uncertainty in the fault geometry is not included in the logic tree. To acknowledge the effect of earthquakes that are not associated with the defined rupture systems on the hazard, a background zone is introduced and the seismicity rates in the background zone are calculated using smoothed-seismicity approach. The state-of-the-art SSC model presented here is the first fully documented and ready-to-use fault-based SSC model developed for the PSHA of Istanbul.

Economic consequences of earthquakes: bridging research and practice with HayWired

NASA Astrophysics Data System (ADS)

Wein, A. M.; Kroll, C.

2016-12-01

The U.S. Geological Survey partners with organizations and experts to develop multiple hazard scenarios. The HayWired earthquake scenario refers to a rupture of the Hayward fault in the Bay Area of California and addresses the potential chaos related to interconnectedness at many levels: the fault afterslip and aftershocks, interdependencies of lifelines, wired/wireless technology, communities at risk, and ripple effects throughout today's digital economy. The scenario is intended for diverse audiences. HayWired analyses translate earthquake hazards (surface rupture, ground shaking, liquefaction, landslides) into physical engineering and environmental health impacts, and into societal consequences. Damages to life and property and lifeline service disruptions are direct causes of business interruption. Economic models are used to estimate the economic impacts and resilience in the regional economy. The objective of the economic analysis is to inform policy discourse about economic resilience at all three levels of the economy: macro, meso, and micro. Stakeholders include businesses, economic development, and community leaders. Previous scenario analyses indicate the size of an event: large earthquakes and large winter storms are both "big ones" for California. They motivate actions to reduce the losses from fire following earthquake and water supply outages. They show the effect that resilience can have on reducing economic losses. Evaluators find that stakeholders learned the most about the economic consequences.

The Differences in Source Dynamics Between Intermediate-Depth and Deep EARTHQUAKES:A Comparative Study Between the 2014 Rat Islands Intermediate-Depth Earthquake and the 2015 Bonin Islands Deep Earthquake

NASA Astrophysics Data System (ADS)

Twardzik, C.; Ji, C.

2015-12-01

It has been proposed that the mechanisms for intermediate-depth and deep earthquakes might be different. While previous extensive seismological studies suggested that such potential differences do not significantly affect the scaling relationships of earthquake parameters, there has been only a few investigations regarding their dynamic characteristics, especially for fracture energy. In this work, the 2014 Mw7.9 Rat Islands intermediate-depth (105 km) earthquake and the 2015 Mw7.8 Bonin Islands deep (680 km) earthquake are studied from two different perspectives. First, their kinematic rupture models are constrained using teleseismic body waves. Our analysis reveals that the Rat Islands earthquake breaks the entire cold core of the subducting slab defined as the depth of the 650oC isotherm. The inverted stress drop is 4 MPa, compatible to that of intra-plate earthquakes at shallow depths. On the other hand, the kinematic rupture model of the Bonin Islands earthquake, which occurred in a region lacking of seismicity for the past forty years, according to the GCMT catalog, exhibits an energetic rupture within a 35 km by 30 km slip patch and a high stress drop of 24 MPa. It is of interest to note that although complex rupture patterns are allowed to match the observations, the inverted slip distributions of these two earthquakes are simple enough to be approximated as the summation of a few circular/elliptical slip patches. Thus, we investigate subsequently their dynamic rupture models. We use a simple modelling approach in which we assume that the dynamic rupture propagation obeys a slip-weakening friction law, and we describe the distribution of stress and friction on the fault as a set of elliptical patches. We will constrain the three dynamic parameters that are yield stress, background stress prior to the rupture and slip weakening distance, as well as the shape of the elliptical patches directly from teleseismic body waves observations. The study would help us getting a better understanding of the dynamic conditions that control the rupture behaviour of these two types of earthquakes, and subsequently improving our knowledge of the dynamics of subducting slabs.

To what extent the repeating earthquakes repeated? - Analyses of 1982 and 2008 Ibaraki-ken-oki M7 class earthquakes using strong motion records -

NASA Astrophysics Data System (ADS)

Takiguchi, M.; Asano, K.; Iwata, T.

2010-12-01

Two M7 class subduction zone earthquakes have occurred in the Ibaraki-ken-oki region, northeast Japan, at 23:23 on July 23, 1982 JST (Mw7.0; 1982MS) and at 01:45 on May 8, 2008 JST (Mw6.8; 2008MS). It has been reported that, from the results of the teleseismic waveform inversion, the rupture of the asperity repeated (HERP, 2010). We estimated the source processes of these earthquakes in detail by analyzing the strong motion records and discussed how much the source characteristics of the two earthquakes repeated. First, we estimated the source model of 2008MS following the method of Miyake et al. (2003). The best-fit set of the model parameters was determined by a grid search using forward modeling of broad-band ground motions. A single 12.6 km × 12.6 km rectangular Strong Motion Generation Area (SMGA, Miyake et al., 2003) was estimated. The rupture of the SMGA of 2008MS (2008SMGA) started from the hypocenter and propagated mainly to northeast. Next, we estimated the source model of 1982MS. We compared the waveforms of 1982MS and 2008MS recorded at the same stations and found the initial rupture phase before the main rupture phase on the waveforms of 1982MS. The travel time analysis showed that the main rupture of the 1982MS started approximately 33 km west of the hypocenter at about 11s after the origin time. The main rupture starting point was located inside 2008SMGA, suggesting that the two SMGAs overlapped in part. The seismic moment ratio of 1982MS to 2008MS was approximately 1.6, and we also found the observed acceleration amplitude spectra of 1982MS were 1.5 times higher than those of 2008MS in the available frequency range. We performed the waveform modeling for 1982MS with a constraint of these ratios. A single rectangular SMGA (1982SMGA) was estimated for the main rupture, which had the same size and the same rupture propagation direction as those of 2008SMGA. However, the estimated stress drop or average slip amount of 1982SMGA was 1.5 times larger than those of 2008SMGA.

Dissociation of intracellular lysosomal rupture from the cell death caused by silica

PubMed Central

Kane, AB; Stanton, RP; Raymond, EG; Dobson, ME; Knafelc, ME; Farber, JL

1980-01-01

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins. PMID:6161936

[Experimental study of multiple organ injuries after high-velocity missiles].

PubMed

Fu, X B

1990-06-01

Multiple organ injuries after high-velocity missiles shot were studied on the 8 pigs. The experimental results showed that (1) more than two organs (the maximum six organs) wounded could be seen in all the pigs; (2) the injuries were characterized by hemorrhage, tissue rupture and hematoma, etc., the pathologic changes were local edema and necrosis; (3) the marked increase of LPO on the vital organs indicates that multiple organ injuries can also occur at the molecular level; (4) they are due to direct effects of pressure waves and not to shock or infection.

Effects of Stretching Speed on Mechanical Rupture of Phospholipid/Cholesterol Bilayers: Molecular Dynamics Simulation

PubMed Central

Shigematsu, Taiki; Koshiyama, Kenichiro; Wada, Shigeo

2015-01-01

Rupture of biological cell membrane under mechanical stresses is critical for cell viability. It is triggered by local rearrangements of membrane molecules. We investigated the effects of stretching speed on mechanical rupture of phospholipid/cholesterol bilayers using unsteady molecular dynamics simulations. We focused on pore formation, the trigger of rupture, in a 40 mol% cholesterol-including bilayer. The unsteady stretching was modeled by proportional and temporal scaling of atom positions at stretching speeds from 0.025 to 30 m/s. The effects of the stretching speed on the critical areal strain, where the pore forms, is composed of two regimes. At low speeds (<1.0 m/s), the critical areal strain is insensitive to speed, whereas it significantly increases at higher speeds. Also, the strain is larger than that of a pure bilayer, regardless of the stretching speeds, which qualitatively agrees with available experimental data. Transient recovery of the cholesterol and phospholipid molecular orientations was evident at lower speeds, suggesting the formation of a stretch-induced interdigitated gel-like phase. However, this recovery was not confirmed at higher speeds or for the pure bilayer. The different responses of the molecular orientations may help explain the two regimes for the effect of stretching speed on pore formation. PMID:26471872

Preoperative Evaluation and Endovascular Procedure of Intraoperative Aneurysm Rupture During Thoracic Endovascular Aortic Repair

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

Zha, Bin-Shan, E-mail: binszha2013@163.com; Zhu, Hua-Gang, E-mail: huagzhu@yeah.net; Ye, Yu-Sheng, E-mail: yeyusheng@aliyun.com

Thoracic aortic aneurysms are now routinely repaired with endovascular repair if anatomically feasible because of advantages in safety and recovery. However, intraoperative aneurysm rupture is a severe complication which may have an adverse effect on the outcome of treatment. Comprehensive preoperative assessment and considerate treatment are keys to success of endovascular aneurysm repair, especially during unexpected circumstances. Few cases have reported on intraoperative aortic rupture, which were successfully managed by endovascular treatment. Here, we present a rare case of an intraoperative aneurysm rupture during endovascular repair of thoracic aortic aneurysm with narrow neck and angulated aorta arch (coarctation-associated aneurysm), whichmore » was successfully treated using double access route approach and iliac limbs of infrarenal devices.Level of EvidenceLevel 5.« less

Earthquake cycle modeling of multi-segmented faults: dynamic rupture and ground motion simulation of the 1992 Mw 7.3 Landers earthquake.

NASA Astrophysics Data System (ADS)

Petukhin, A.; Galvez, P.; Somerville, P.; Ampuero, J. P.

2017-12-01

We perform earthquake cycle simulations to study the characteristics of source scaling relations and strong ground motions and in multi-segmented fault ruptures. For earthquake cycle modeling, a quasi-dynamic solver (QDYN, Luo et al, 2016) is used to nucleate events and the fully dynamic solver (SPECFEM3D, Galvez et al., 2014, 2016) is used to simulate earthquake ruptures. The Mw 7.3 Landers earthquake has been chosen as a target earthquake to validate our methodology. The SCEC fault geometry for the three-segmented Landers rupture is included and extended at both ends to a total length of 200 km. We followed the 2-D spatial correlated Dc distributions based on Hillers et. al. (2007) that associates Dc distribution with different degrees of fault maturity. The fault maturity is related to the variability of Dc on a microscopic scale. Large variations of Dc represents immature faults and lower variations of Dc represents mature faults. Moreover we impose a taper (a-b) at the fault edges and limit the fault depth to 15 km. Using these settings, earthquake cycle simulations are performed to nucleate seismic events on different sections of the fault, and dynamic rupture modeling is used to propagate the ruptures. The fault segmentation brings complexity into the rupture process. For instance, the change of strike between fault segments enhances strong variations of stress. In fact, Oglesby and Mai (2012) show the normal stress varies from positive (clamping) to negative (unclamping) between fault segments, which leads to favorable or unfavorable conditions for rupture growth. To replicate these complexities and the effect of fault segmentation in the rupture process, we perform earthquake cycles with dynamic rupture modeling and generate events similar to the Mw 7.3 Landers earthquake. We extract the asperities of these events and analyze the scaling relations between rupture area, average slip and combined area of asperities versus moment magnitude. Finally, the simulated ground motions will be validated by comparison of simulated response spectra with recorded response spectra and with response spectra from ground motion prediction models. This research is sponsored by the Japan Nuclear Regulation Authority.

Transabdominal amnioinfusion for improving fetal outcomes after oligohydramnios secondary to preterm prelabour rupture of membranes before 26 weeks.

PubMed

Van Teeffelen, Stijn; Pajkrt, Eva; Willekes, Christine; Van Kuijk, Sander M J; Mol, Ben Willem J

2013-08-03

Preterm prelabour rupture of membranes (PPROM) before 26 weeks can delay lung development and can cause pulmonary hypoplasia, as a result of oligohydramnios. Restoring the amniotic fluid volume by transabdominal amnioinfusion might prevent abnormal lung development and might have a protective effect for neurological complications, fetal deformities and neonatal sepsis. To assess the effectiveness of transabdominal amnioinfusion in improving perinatal outcome in women with oligohydramnios secondary to rupture of fetal membranes before 26 weeks. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2013). All randomised controlled trials comparing transabdominal amnioinfusion with no transabdominal amnioinfusion. Cluster- or quasi-randomised trials were not eligible for inclusion. In cases where only an abstract was available, we attempted to find the full articles. Two review authors assessed trials for inclusion. No eligible trials were identified. There are no included studies. There is currently no evidence to evaluate the use of transabdominal amnioinfusion in women with oligohydramnios secondary to rupture of fetal membranes before 26 weeks for improving perinatal outcome. Further research examining the effects of this intervention is needed. Two randomised controlled trials are ongoing but final data have not yet been published.

Rupture Directivity Effect on Seismic Vulnerability of Reinforced Concrete Bridge

NASA Astrophysics Data System (ADS)

Shirazian, Shadi; Nouri, Gholamreza; Ghayamghamian, Mohamadreza

2017-04-01

Earthquake catastrophes menace humans` lives and assets. Although earthquakes are inevitable, damage is not. To remedy this situation, significant amount of research is conducted in order to assess the performance of existent man-made structures, particularly infrastructures such as bridges which play a vital role in post earthquake services. The results can be used for assessing retrofit prioritization for structures and as a basis for economic loss estimations. The research presented here determines the vulnerability of a common typical two-span reinforced concrete bridge by generating fragility curves. Near-fault ground motions are different from ordinary ground motions, often containing strong coherent dynamic long-period pulses and permanent ground displacements. Here special attention is given to this type of ground motions, and their effects on the seismic behavior of structure are compared with ordinary motions. The results show near-fault ground motions exacerbate the seismic vulnerability of a bridge by about 68% in comparison with near-field ground motions. In other words, near-source ground motions with forward directivity effect are more dangerous.

Direct Surgery of Previously Coiled Large Internal Carotid Ophthalmic Aneurysm for the Purpose of Optic Nerve Decompression

PubMed Central

Kawabata, Shuhei; Toyota, Shingo; Kumagai, Tetsuya; Goto, Tetsu; Mori, Kanji; Taki, Takuyu

2017-01-01

Background Progressive visual loss after coil embolization of a large internal carotid ophthalmic aneurysm has been widely reported. It is generally accepted that the primary strategy for this complication should be conservative, including steroid therapy; however, it is not well known as to what approach to take when the conservative therapy is not effective. Case Presentation We report a case of a 55-year-old female presenting with progressive visual loss after the coiling of a ruptured large internal carotid ophthalmic aneurysm. As the conservative therapy had not been effective, we performed neck clipping of the aneurysm with optic canal unroofing, anterior clinoidectomy, and partial removal of the embolized coils for the purpose of optic nerve decompression. After the surgery, the visual symptom was improved markedly. Conclusions It is suggested that direct surgery for the purpose of optic nerve decompression may be one of the options when conservative therapy is not effective for progressive visual disturbance after coil embolization. PMID:28229036

Preliminary analysis of strong-motion recordings from the 28 September 2004 Parkfield, California earthquake

USGS Publications Warehouse

Shakal, A.; Graizer, V.; Huang, M.; Borcherdt, R.; Haddadi, H.; Lin, K.-W.; Stephens, C.; Roffers, P.

2005-01-01

The Parkfield 2004 earthquake yielded the most extensive set of strong-motion data in the near-source region of a magnitude 6 earthquake yet obtained. The recordings of acceleration and volumetric strain provide an unprecedented document of the near-source seismic radiation for a moderate earthquake. The spatial density of the measurements alon g the fault zone and in the linear arrays perpendicular to the fault is expected to provide an exceptional opportunity to develop improved models of the rupture process. The closely spaced measurements should help infer the temporal and spatial distribution of the rupture process at much higher resolution than previously possible. Preliminary analyses of the peak a cceleration data presented herein shows that the motions vary significantly along the rupture zone, from 0.13 g to more than 2.5 g, with a map of the values showing that the larger values are concentrated in three areas. Particle motions at the near-fault stations are consistent with bilateral rupture. Fault-normal pulses similar to those observed in recent strike-slip earthquakes are apparent at several of the stations. The attenuation of peak ground acceleration with distance is more rapid than that indicated by some standard relationships but adequately fits others. Evidence for directivity in the peak acceleration data is not strong. Several stations very near, or over, the rupturing fault recorded relatively low accelerations. These recordings may provide a quantitative basis to understand observations of low near-fault shaking damage that has been reported in other large strike-slip earthquak.

Trench-breaching afterslip following deeper coseismic slip of the 2012 Mw 7.6 Costa Rica earthquake constrained by near-trench pressure and land-based geodetic observations

NASA Astrophysics Data System (ADS)

Sun, Tianhaozhe; Davis, Earl E.; Wang, Kelin; Jiang, Yan

2017-12-01

Large rupture of the shallowest portion of subduction thrust faults (megathrusts), such as during the 2011 moment magnitude (Mw) 9.0 Tohoku-oki earthquake, can generate the most devastating tsunamis. However, it remains unclear whether such trench-breaching rupture is typical of other subduction earthquakes. The main difficulty in answering this question is the common lack of near-trench geodetic monitoring in subduction zones worldwide. Seafloor and sub-seafloor fluid pressure measurements at two closely located borehole observatories in the Middle America trench have provided clear evidence for the absence of trench-breaching rupture during the 2012 Mw 7.6 Costa Rica earthquake, and for the presence of substantial trench-breaching afterslip at slow rates after the rupture (Davis et al., 2015). In this study, we compare postseismic seafloor pressure change at the trench with coastal Global Navigation Satellite System (GNSS) displacements. The same temporal characteristics of the deformation at the trench and coastal sites indicate that both offshore and onshore deformation were the consequence of afterslip that occurred over a wide spatial range updip of the rupture. By determining the co- and post-seismic slip distributions and inferring the associated shear stress changes on the megathrust, we show that the mechanical behaviour varies in the dip direction. The slip behaviour of the shallow megathrust at Costa Rica is consistent with conventional conceptual models, and contrasts with the behaviour of the shallowest megathrust during the Tohoku-oki event.

Co-seismic ruptures of the 12 May 2008, Ms 8.0 Wenchuan earthquake, Sichuan: East-west crustal shortening on oblique, parallel thrusts along the eastern edge of Tibet

USGS Publications Warehouse

Liu-Zeng, J.; Zhang, Z.; Wen, L.; Tapponnier, P.; Sun, Jielun; Xing, X.; Hu, G.; Xu, Q.; Zeng, L.; Ding, L.; Ji, C.; Hudnut, K.W.; van der Woerd, J.

2009-01-01

The Ms 8.0, Wenchuan earthquake, which devastated the mountainous western rim of the Sichuan basin in central China, produced a surface rupture over 200??km-long with oblique thrust/dextral slip and maximum scarp heights of ~ 10??m. It thus ranks as one of the world's largest continental mega-thrust events in the last 150??yrs. Field investigation shows clear surface breaks along two of the main branches of the NE-trending Longmen Shan thrust fault system. The principal rupture, on the NW-dipping Beichuan fault, displays nearly equal amounts of thrust and right-lateral slip. Basin-ward of this rupture, another continuous surface break is observed for over 70??km on the parallel, more shallowly NW-dipping Pengguan fault. Slip on this latter fault was pure thrusting, with a maximum scarp height of ~ 3.5??m. This is one of the very few reported instances of crustal-scale co-seismic slip partitioning on parallel thrusts. This out-of-sequence event, with distributed surface breaks on crustal mega-thrusts, highlights regional, ~ EW-directed, present day crustal shortening oblique to the Longmen Shan margin of Tibet. The long rupture and large offsets with strong horizontal shortening that characterize the Wenchuan earthquake herald a re-evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau, and require a re-assessment of seismic hazard along potentially under-rated active faults across the densely populated western Sichuan basin and mountains. ?? 2009 Elsevier B.V.

Atmospheric Pressure and Abdominal Aortic Aneurysm Rupture: Results From a Time Series Analysis and Case-Crossover Study.

PubMed

Penning de Vries, Bas B L; Kolkert, Joé L P; Meerwaldt, Robbert; Groenwold, Rolf H H

2017-10-01

Associations between atmospheric pressure and abdominal aortic aneurysm (AAA) rupture risk have been reported, but empirical evidence is inconclusive and largely derived from studies that did not account for possible nonlinearity, seasonality, and confounding by temperature. Associations between atmospheric pressure and AAA rupture risk were investigated using local meteorological data and a case series of 358 patients admitted to hospital for ruptured AAA during the study period, January 2002 to December 2012. Two analyses were performed-a time series analysis and a case-crossover study. Results from the 2 analyses were similar; neither the time series analysis nor the case-crossover study showed a significant association between atmospheric pressure ( P = .627 and P = .625, respectively, for mean daily atmospheric pressure) or atmospheric pressure variation ( P = .464 and P = .816, respectively, for 24-hour change in mean daily atmospheric pressure) and AAA rupture risk. This study failed to support claims that atmospheric pressure causally affects AAA rupture risk. In interpreting our results, one should be aware that the range of atmospheric pressure observed in this study is not representative of the atmospheric pressure to which patients with AAA may be exposed, for example, during air travel or travel to high altitudes in the mountains. Making firm claims regarding these conditions in relation to AAA rupture risk is difficult at best. Furthermore, despite the fact that we used one of the largest case series to date to investigate the effect of atmospheric pressure on AAA rupture risk, it is possible that this study is simply too small to demonstrate a causal link.

Meta-analysis of peak wall stress in ruptured, symptomatic and intact abdominal aortic aneurysms.

PubMed

Khosla, S; Morris, D R; Moxon, J V; Walker, P J; Gasser, T C; Golledge, J

2014-10-01

Abdominal aortic aneurysm (AAA) is an important cause of sudden death; however, there are currently incomplete means to predict the risk of AAA rupture. AAA peak wall stress (PWS) can be estimated using finite element analysis (FEA) methods from computed tomography (CT) scans. The question is whether AAA PWS can predict AAA rupture. The aim of this systematic review was to compare PWS in patients with ruptured and intact AAA. The MEDLINE database was searched on 25 May 2013. Case-control studies assessing PWS in asymptomatic intact, and acutely symptomatic or ruptured AAA from CT scans using FEA were included. Data were extracted independently. A random-effects model was used to calculate standard mean differences (SMDs) for PWS measurements. Nine studies assessing 348 individuals were identified and used in the meta-analysis. Results from 204 asymptomatic intact and 144 symptomatic or ruptured AAAs showed that PWS was significantly greater in the symptomatic/ ruptured AAAs compared with the asymptomatic intact AAAs (SMD 0·95, 95 per cent confidence interval 0·71 to 1·18; P < 0·001). The findings remained significant after adjustment for mean systolic blood pressure, standardized at 120 mmHg (SMD 0·68, 0·39 to 0·96; P < 0·001). Minimal heterogeneity between studies was noted (I(2)  = 0 per cent). This study suggests that PWS is greater in symptomatic or ruptured AAA than in asymptomatic intact AAA. © 2014 BJS Society Ltd. Published by John Wiley & Sons Ltd.

Coatings for directional eutectics. [for corrosion and oxidation resistance

NASA Technical Reports Server (NTRS)

Felten, E. J.; Strangman, T. E.; Ulion, N. E.

1974-01-01

Eleven coating systems based on MCrAlY overlay and diffusion aluminide prototypes were evaluated to determine their capability for protecting the gamma/gamma prime-delta directionally solidified eutectic alloy (Ni-20Cb-6Cr-2.5Al) in gas turbine engine applications. Furnace oxidation and hot corrosion, Mach 0.37 burner-rig, tensile ductility, stress-rupture and thermomechanical fatigue tests were used to evaluate the coated gamma/gamma prime-delta alloy. The diffusion aluminide coatings provided adequate oxidation resistance at 1144 K (1600 F) but offered very limited protection in 114 K (1600 F) hot corrosion and 1366 K (2000 F) oxidation tests. A platinum modified NiCrAlY overlay coating exhibited excellent performance in oxidation testing and had no adverse effects upon the eutectic alloy.

Fan-head shear rupture mechanism as a source of off-fault tensile cracking

NASA Astrophysics Data System (ADS)

Tarasov, Boris

2016-04-01

This presentation discusses the role of a recently identified fan-head shear rupture mechanism [1] in the creation of off-fault tensile cracks observed in earthquake laboratory experiments conducted on brittle photoelastic specimens [2,3]. According to the fan-mechanism the shear rupture propagation is associated with consecutive creation of small slabs in the fracture tip which, due to rotation caused by shear displacement of the fracture interfaces, form a fan-structure representing the fracture head. The fan-head combines such unique features as: extremely low shear resistance (below the frictional strength) and self-sustaining tensile stress intensification along one side of the interface. The variation of tensile stress within the fan-head zone is like this: it increases with distance from the fracture tip up to a maximum value and then decreases. For the initial formation of the fan-head high local stresses corresponding to the fracture strength should be applied in a small area, however after completions of the fan-head it can propagate dynamically through the material at low shear stresses (even below the frictional strength). The fan-mechanism allows explaining all unique features associated with the off-fault cracking process observed in photoelastic experiments [2,3]. In these experiments spontaneous shear ruptures were nucleated in a bonded, precut, inclined and pre-stressed interface by producing a local pressure pulse in a small area. Isochromatic fringe patterns around a shear rupture propagating along bonded interface indicate the following features of the off-fault tensile crack development: tensile cracks nucleate and grow periodically along one side of the interface at a roughly constant angle (about 80 degrees) relative to the shear rupture interface; the tensile crack nucleation takes place some distance behind the rupture tip; with distance from the point of nucleation tensile cracks grow up to a certain length within the rupture head zone; behind this zone static microcracks are left in the wake of the propagating rupture. Unfortunately, the modern technology used in these experiments is not able to identify the shear rupture mechanism itself operated within the narrow rupture interface. However, a special analysis of side effects accompanying the shear rupture propagation (including the off-fault tensile cracking) allows supposing that the failure process was governed by the fan-mechanism. 1. Tarasov, B.G. 2014. Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression. Tectonophysics, 621, 69-84. 2. Griffith, W.A., Rosakis, A., Pollard, D.D. and Ko, C.W., 2009. Dynamic rupture experiments elucidate tensile crack development during propagating earthquake ruptures, Geology, pp 795-798. 3. Ngo, D., Huang, Y., Rosakis, A., Griffith, W.A., Pollard D. 2012. Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models. Journal of Geophysical Research, vol. 117, B01307, doi: 10.1029/2011JB008577 (2012).

Rupture characteristics of the three M ∼ 4.7 (1992-1994) Parkfield earthquakes

USGS Publications Warehouse

Fletcher, Jon Peter B.; Spudich, Paul A.

1998-01-01

Slip on the San Andreas fault was determined for three M ∼ 4.7 earthquakes using a tomographic inverse system [Beroza and Spudich, 1988] to invert seismic source time functions (STFs) from S waves. STFs were obtained by deconvolving mainshock accelerograms by those from collocated smaller earthquakes. Accelerograms were from the U.S. Geological Survey Parkfield Small Aperture Array (UPSAR) and from a distributed array of digital accelerometer stations at Parkfield. Eight or nine STFs are used in each of the three inversions. STFs are typically symmetrical pulses with a duration of about 0.3–0.5 s. In the inversion, mainshock rise time was set to 0.05 s, and we allowed the rupture time to vary slightly from a constant rupture velocity of approximately 0.85β. Rupture for all three events, which are located in or close to the Middle Mountain preparation zone or box (MMB), quickly reaches a local maximum in slip and then propagates outward to peaks, ridges, or plateaus in the slip distribution. Slip for the October 20, 1992, event (located just inside the southern edge of the MMB) propagates from an initial spike north and updip along a curving ridge for about 2 km. The initial spike continued to grow in the November 14, 1993, event (located north of the October 20, 1992, event just beneath the hypocenter of the 1966 Parkfield earthquake), which shows little directivity, although there is a smaller patch of slip updip and to the south. In contrast, rupture for the December 20, 1994, event (located just south of the October 20, 1992, event) propagated north and slightly updip, creating a rough plateau in slip a few kilometers wide on a side. Directivity for this event also is to the north. Directivity for all three events points in the approximate direction of the 1966 hypocenter. Small pulses, which comprise a coda, are found on the STFs for several seconds after the initial impulsive event. Several tests based on the assumption that the average of all STFs from UPSAR for each event is an estimate of the true slip at the source suggest that the codas in the STFs are S waves from a long-duration source rather than uncorrected site response. An initiation phase is found on the array average for the November 14, 1993, and December 20, 1994, events. These precursory phases are the result of a spike in slip at the hypocenter. A value of 2.4–4 mm is obtained for Dc, the slip-weakening distance, by interpreting the initial spike as a critical patch. The few aftershocks for the October 20, 1992, event are distributed to the north and updip of the mainshock, but the November 14, 1993, event had a strong burst of aftershock activity that propagated to the north of its hypocenter at roughly the same depth. Aftershocks of the December 20, 1994, event are mostly updip. The November 14, 1993, event had the simplest slip distribution, appeared to be the most impulsive, and had the most active aftershock sequence and the greatest depth. If the eventual Parkfield earthquake initiates near the 1966 hypocenter, then the directivity of the three events studied here will have pointed to it. However, it is certainly possible that both the initiation of characteristic Parkfield shocks and the directivity of smaller events are controlled by fault properties on a larger scale such as by fault bends or jogs.

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.

Relation between energy radiation ratio and rupture speed in numerically simulated earthquakes

NASA Astrophysics Data System (ADS)

Noda, H.; Lapusta, N.; Kanamori, H.

2011-12-01

One of the prominent questions in seismology is energy partitioning during an earthquake. Venkataraman and Kanamori [2004] discussed radiation ratio η_R, the ratio of radiated energy E_R to partial strain energy change ΔW_0 which is the total released strain energy minus the energy that would have been dissipated if a fault had slipped at the final stress. They found positive correlation between η_R and rupture speed in large earthquakes, and compared these data with theoretical estimates from simplified models. The relation between η_R and rupture speed is of great interest since both quantities can be estimated independently although there are large uncertainties. We conduct numerical simulations of dynamic ruptures and study the obtained energy partitioning (and η_R) and averaged rupture speeds V_r. So far, we have considered problems based on TPV103 from the SCEC/USGS Spontaneous Rupture Code Verification Project [Harris et al., 2009, http://scecdata.usc.edu/cvws/], which is a 3-D problem with the possibility of remarkable rate weakening at coseismic slip rates caused by flash heating of microscopic asperities [Rice, 1999]. We study the effect of background shear stress level τ_b and the manner in which rupture is arrested, either in rate-strengthening or unbreakable areas of the fault. Note that rupture speed at each fault point is defined when the rupture is still in progress, while η_R is defined after all dynamic processes such as propagation of a rupture front, healing fronts, and seismic waves have been completed. Those complexities may cause a difference from the theoretical estimates based on simple models, an issue we explore in this study. Overall, our simulations produce the relation between η_R and V_r broadly consistent with the study of Venkataraman and Kanamori (2004) for natural earthquakes and the corresponding theoretical estimates. The model by Mott [1948] agrees best with the cases studied so far, although it is not rigorously correct [Freund, 1990]. For example, a case which is similar to TPV103 except in the nucleation procedure yields a pulse-like rupture with a spatially averaged rupture speed V_r = 0.59 c_s and η_R = 0.32, while the theoretical estimates [Fossum and Freund, 1975 for mode II and Kostrov, 1966; Ehselby, 1969 for mode III] predict η_R of about 0.5 for this rupture speed. This difference is not significant compared with the large observational error. As τ_b increases, V_r increases monotonically, while η_R exhibits more complex behavior: it increases with τ_b for pulse-like ruptures, decreases by about 0.1 at the transition to crack-like ruptures, and then increases again. Frictional dissipation is significant when a rupture front reaches a rate-strengthening region. If the barrier is changed to an unbreakable region, η_R decreases and V_r/c_s increases at most by 0.3 and 0.1, respectively. Although sharper arrest of rupture causes larger E_R per seismic moment due to the stopping phases, ΔW_0 per seismic moment increases more remarkably due to large wavenumber components in final slip distribution.

Parent artery occlusion for ruptured "true" posterior communicating artery aneurysm.

PubMed

Mitsuhashi, Takashi; Takeda, Nobuaki; Oishi, Hidenori; Arai, Hajime

2015-04-01

A case of a patient with a ruptured true posterior communicating artery (PCoA) aneurysm is reported, who had been managed by early endovascular parent artery occlusion with coils. The small blister aneurysm was located at the proximal PCoA itself and directed superiorly. Postoperative course was uneventful. During 1-month follow-up, the patient recovered well and could care for herself. Aneurysms of the PCoA itself are very rare. As reported to date, surgical procedures would favor microsurgical clipping over endovascular coil embolization. Endovascular treatment may be a good alternative to surgical trapping for true PCoA blister aneurysm. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Synergy and Interactions Among Biological Pathways Leading to Preterm Premature Rupture of Membranes

PubMed Central

Lannon, Sophia M. R.; Vanderhoeven, Jeroen P.; Eschenbach, David A.; Gravett, Michael G.; Waldorf, Kristina M. Adams

2014-01-01

Preterm premature rupture of membranes (PPROM) occurs in 1% to 2% of births. Impact of PPROM is greatest in low- and middle-income countries where prematurity-related deaths are most common. Recent investigations identify cytokine and matrix metalloproteinase activation, oxidative stress, and apoptosis as primary pathways to PPROM. These biological processes are initiated by heterogeneous etiologies including infection/inflammation, placental bleeding, uterine overdistention, and genetic polymorphisms. We hypothesize that pathways to PPROM overlap and act synergistically to weaken membranes. We focus our discussion on membrane composition and strength, pathways linking risk factors to membrane weakening, and future research directions to reduce the global burden of PPROM. PMID:24840939

An integrated analysis on source parameters, seismogenic structure and seismic hazard of the 2014 Ms 6.3 Kangding earthquake

NASA Astrophysics Data System (ADS)

Zheng, Y.

2016-12-01

On November 22, 2014, the Ms6.3 Kangding earthquake ended 30 years of history of no strong earthquake at the Xianshuihe fault zone. The focal mechanism and centroid depth of the Kangding earthquake are inverted by teleseismic waveforms and regional seismograms with CAP method. The result shows that the two nodal planes of focal mechanism are 235°/82°/-173° and 144°/83°/-8° respectively, the latter nodal plane should be the ruptured fault plane with a focal depth of 9 km. The rupture process model of the Kangding earthquake is obtained by joint inversion of teleseismic data and regional seismograms. The Kangding earthquake is a bilateral earthquake, and the major rupture zone is within a depth range of 5-15 km, spanning 10 km and 12 km along dip and strike directions, and maximum slip is about 0.5m. Most seismic moment was released during the first 5 s and the magnitude is Mw6.01, smaller than the model determined by InSAR data. The discrepancy between co-seismic rupture models of the Kangding and its Ms 5.8 aftershock and the InSAR model implies significant afterslip deformation occurred in the two weeks after the mainshock. The afterslip released energy equals to an Mw5.9 earthquake and mainly concentrates in the northwest side and the shallower side to the rupture zone. The CFS accumulation near the epicenter of the 2014 Kangding earthquake is increased by the 2008 Wenchuan earthquake, implying that the Kangding earthquake could be triggered by the Wenchuan earthquake. The CFS at the northwest section of the seismic gap along the Kangding-daofu segment is increased by the Kanding earthquake, and the rupture slip of the Kangding earthquake sequence is too small to release the accumulated strain in the seismic gap. Consequently, the northwest section of the Kangding-daofu seismic gap is under high seismic hazard in the future.

Dynamic Rupture Modeling in Three Dimensions on Unstructured Meshes Using a Discontinuous Galerkin Method

NASA Astrophysics Data System (ADS)

Pelties, C.; Käser, M.

2010-12-01

We will present recent developments concerning the extensions of the ADER-DG method to solve three dimensional dynamic rupture problems on unstructured tetrahedral meshes. The simulation of earthquake rupture dynamics and seismic wave propagation using a discontinuous Galerkin (DG) method in 2D was recently presented by J. de la Puente et al. (2009). A considerable feature of this study regarding spontaneous rupture problems was the combination of the DG scheme and a time integration method using Arbitrarily high-order DERivatives (ADER) to provide high accuracy in space and time with the discretization on unstructured meshes. In the resulting discrete velocity-stress formulation of the elastic wave equations variables are naturally discontinuous at the interfaces between elements. The so-called Riemann problem can then be solved to obtain well defined values of the variables at the discontinuity itself. This is in particular valid for the fault at which a certain friction law has to be evaluated. Hence, the fault’s geometry is honored by the computational mesh. This way, complex fault planes can be modeled adequately with small elements while fast mesh coarsening is possible with increasing distance from the fault. Due to the strict locality of the scheme using only direct neighbor communication, excellent parallel behavior can be observed. A further advantage of the scheme is that it avoids spurious high-frequency contributions in the slip rate spectra and therefore does not require artificial Kelvin-Voigt damping or filtering of synthetic seismograms. In order to test the accuracy of the ADER-DG method the Southern California Earthquake Center (SCEC) benchmark for spontaneous rupture simulations was employed. Reference: J. de la Puente, J.-P. Ampuero, and M. Käser (2009), Dynamic rupture modeling on unstructured meshes using a discontinuous Galerkin method, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, B10302, doi:10.1029/2008JB006271

[Risk factors of rupture of internal carotid artery during surgical resection of carotid body tumor].

PubMed

Li, Y H; Wang, J S; Yao, C; Chang, G Q; Yin, H H; Li, S Q; Lü, W M; Hu, Z J; Wang, S M

2017-06-13

Objective: To investigate risk factors of rupture of internal carotid artery resection during carotid body tumor resection and to summarize our treatment experience. Methods: During the period from 1991 to 2016, rupture of internal carotid artery occurred in 27 patients (28 tumors) during surgical resection of carotid body tumor in the First Affiliated Hospital of Sun Yat-sen University. Their clinical and follow-up data were retrospectively collected and analyzed. For all patients underwent surgical resection during this period, Logistic regression analysis was used to investigate the risk factors of intraoperative rupture of internal carotid artery. Results: Of these 28 tumors, there were 15 (53.6%) tumors with diameter≥5 cm and 20 (71.4%) Shamblin Ⅲ tumors. Intraoperatively, shunt was applied for 8 (28.6%) cases. Thirteen (46.4%) patients underwent ligation of external carotid artery, while 2 (7.1%) patients accepted resection of cranial nerves. Direct closure/patchplasty, autologous vessels or graft reconstruction was used in 16, 10 and 2 cases, respectively. Postoperatively, stroke occurred in 4(14.3%) cases and cranial nerve deficit in 15 (53.6%) cases. During a median length of 36 (14-125) months, cranial nerve deficit persisted in 5 cases. Follow-up radiologic examination indicated 3 (10.7%) cases of targeted vessel occlusion. However, no new-onset stroke was identified. Among all patients underwent surgical resection of carotid body tumor, female ( OR =3.650, P =0.012), age≤25 years old ( OR =3.710, P =0.013) and Shamblin Ⅲ tumor ( OR =4.631, P =0.008) increase the risks of intraoperative carotid artery rupture. Conclusions: Shamblin Ⅲ tumor is the predictor of rupture of internal carotid artery. Intraoperative, properly increased blood pressure, intraoperative heparinization and use of shunt for those cases without well-compensated cranial collateral arteries are likely to decreasing the incidence of stroke.

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.

Flexible kinematic earthquake rupture inversion of tele-seismic waveforms: Application to the 2013 Balochistan, Pakistan earthquake

NASA Astrophysics Data System (ADS)

Shimizu, K.; Yagi, Y.; Okuwaki, R.; Kasahara, A.

2017-12-01

The kinematic earthquake rupture models are useful to derive statistics and scaling properties of the large and great earthquakes. However, the kinematic rupture models for the same earthquake are often different from one another. Such sensitivity of the modeling prevents us to understand the statistics and scaling properties of the earthquakes. Yagi and Fukahata (2011) introduces the uncertainty of Green's function into the tele-seismic waveform inversion, and shows that the stable spatiotemporal distribution of slip-rate can be obtained by using an empirical Bayesian scheme. One of the unsolved problems in the inversion rises from the modeling error originated from an uncertainty of a fault-model setting. Green's function near the nodal plane of focal mechanism is known to be sensitive to the slight change of the assumed fault geometry, and thus the spatiotemporal distribution of slip-rate should be distorted by the modeling error originated from the uncertainty of the fault model. We propose a new method accounting for the complexity in the fault geometry by additionally solving the focal mechanism on each space knot. Since a solution of finite source inversion gets unstable with an increasing of flexibility of the model, we try to estimate a stable spatiotemporal distribution of focal mechanism in the framework of Yagi and Fukahata (2011). We applied the proposed method to the 52 tele-seismic P-waveforms of the 2013 Balochistan, Pakistan earthquake. The inverted-potency distribution shows unilateral rupture propagation toward southwest of the epicenter, and the spatial variation of the focal mechanisms shares the same pattern as the fault-curvature along the tectonic fabric. On the other hand, the broad pattern of rupture process, including the direction of rupture propagation, cannot be reproduced by an inversion analysis under the assumption that the faulting occurred on a single flat plane. These results show that the modeling error caused by simplifying the fault model is non-negligible in the tele-seismic waveform inversion of the 2013 Balochistan, Pakistan earthquake.

Matrix metalloproteinase activity in stifle synovial fluid of cranial cruciate ligament deficient dogs and effect of postoperative doxycycline treatment.

PubMed

Rabillard, M; Danger, R; Doran, I P; Niebauer, G W; Brouard, S; Gauthier, O

2012-07-01

This prospective clinical study investigated the activity of matrix metalloproteinases (MMPs) in stifle synovial fluid (SF) of 13 dogs with acute cranial cruciate ligament (CCL) rupture, and the effect of a postoperative doxycycline treatment. MMP-2, 3, 9 and 13 activities were compared with respect to the time of sampling (preoperatively or 1 month after surgical stabilisation) and the type of postoperative adjuvant treatment (doxycycline or not). No significant activity was detected for both MMP-3 and MMP-13. MMP-2 and MMP-9 activities were found to be significantly highly increased in SF of CCL ruptured stifles compared to control stifles of unaffected dogs. No significant effect from surgical stabilisation and postoperative doxycycline treatment on MMP-2 and MMP-9 activities was found, indicating that doxycycline may not be an appropriate postoperative medical treatment after CCL rupture. Copyright © 2011 Elsevier Ltd. All rights reserved.

Phenytoin accelerates tendon healing in a rat model of Achilles tendon rupture.

PubMed

Hajipour, B; Navali, A M; Mohammad, S Ali; Mousavi, G; Akbari, M Gahvechi; Miyandoab, T Maleki; Roshangar, L; Saleh, B Mohammadi; Kermani, T Asvadi; Laleh, F Moutab; Ghabili, M

2016-01-01

Tendons are vulnerable to various types of acute or chronic injures. Different methods have been investigated to achieve better healing. Phenytoin is a drug which could stimulate fibroblasts to produce collagen. This experimental study was performed to assess the effect of phenytoin on tendon healing in a rat model of tendon rupture. Thirty healthy rats were divided into 3 groups, 1) Sham group; 2) Tendon rupture; 3) Tendon rupture+phenytoin (100 mg/kg intraperitoneally) for 21 days. On 21st day after tendon injury, the rats were anesthetized and tendon tissue was sampled for studying by light and electron microscopy. Qualitative and quantitative microscopic comparisons of the repair tissues of both groups were made on the 21st day. The results obtained from light and electron microscopy studies showed that tendon tissue healing was significantly better in phenytoin group compared to the control group (p < 0.05). Systemic administration of phenytoin may have a positive effect on tendon healing by increasing fibroblast quantity, fibrillar collagen synthesis, vascularity, and suppressing inflammation (Tab. 2, Ref. 25).

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.

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.

Effect of the loading rate on compressive properties of goose eggs.

PubMed

Nedomová, Š; Kumbár, V; Trnka, J; Buchar, J

2016-03-01

The resistance of goose (Anser anser f. domestica) eggs to damage was determined by measuring the average rupture force, specific deformation and rupture energy during their compression at different compression speeds (0.0167, 0.167, 0.334, 1.67, 6.68 and 13.36 mm/s). Eggs have been loaded between their poles (along X axis) and in the equator plane (Z axis). The greatest amount of force required to break the eggs was required when eggs were loaded along the X axis and the least compression force was required along the Z axis. This effect of the loading orientation can be described in terms of the eggshell contour curvature. The rate sensitivity of the eggshell rupture force is higher than that observed for the Japanese quail's eggs.