Science.gov

Sample records for active slip systems

  1. Dislocation boundaries and active slip systems

    SciTech Connect

    Wert, J.A.; Hansen, N.

    1995-11-01

    Part of the dislocations which have participated in the plastic deformation of a polycrystalline metal are stored in dislocation boundaries in a two- or three-dimensional arrangement. The dislocation in such boundaries can be analyzed by determining the misorientation between neighboring crystallites and the boundary orientation. Information about the dislocations in the boundaries can also be obtained by an analysis of active slip systems based on the crystallite orientation and the imposed stress or strain state in combination with appropriate constraint conditions. In the present paper an analysis of the boundary dislocation structure and of the slip systems has been conducted for pure aluminium cold-rolled to a von Mises strain of 0.41. The results show that a substantial majority of dislocations in different types of dislocation boundaries are from the primary and conjugate slip system in the adjoining crystallites. A basis is therefore provided for integrating deformation structure observations with plastic deformation behavior.

  2. Plane constrained shear of single crystal strip with two active slip systems

    NASA Astrophysics Data System (ADS)

    Le, K. C.; Sembiring, P.

    Within continuum dislocation theory the plane constrained shear of a single crystal strip with two active slip systems is considered. An analytical solution is found for symmetric double slip which exhibits the energetic and dissipative thresholds for dislocation nucleation, the Bauschinger translational work hardening, and the size effects. Comparison with discrete dislocation simulations shows good agreement between the discrete and continuum approaches. Numerical procedures in the general case of non-symmetric double slip are proposed.

  3. Investigation of active slip systems in high purity single crystal niobium

    NASA Astrophysics Data System (ADS)

    Baars, Derek

    The superconducting radio-frequency (SRF) community uses high purity niobium to manufacture SRF cavities for a variety of accelerator applications. Cavities are either made from large-grain sheets cut directly from the ingot and formed, or the ingot microstructure is broken down to form polycrystalline sheets or tubes. Reducing the number of costly electron beam welds to assemble the cavities is also desired. A greater understanding of the active slip systems and their relation to subsequent dislocation substructure would be of use in all these areas, to better understand how large grain niobium deforms and to develop more accurate computational models that will aid in the design and use of more cost-effective forming methods. Studies of slip in high-purity niobium suggest that temperature, material purity, and crystal orientation affect which slip systems are active during deformation, though have not examined the somewhat lesser purity niobium used for SRF cavities. As a step toward these goals, two sets of SRF-purity single crystal niobium samples were deformed to 40% strain in tension at room temperature. The first set was cut and welded back together. The second set consisted of deliberately orientated samples that resolved shear stress onto desired slip systems to evaluate different combinations of slip. Determining likely active slip systems was complex, though the evidence suggests that {112} slip may be dominant at yield at room temperature as suggested by theory, though {110} slip could not be ruled out.

  4. Experimental Deformation of Olivine Single Crystal at Mantle P and T: Pressure Effect on Olivine Dislocation Slip-System Activities

    NASA Astrophysics Data System (ADS)

    Paul, R.; Girard, J.; Chen, J.; Amiguet, E.

    2008-12-01

    Seismic velocity anisotropies observed in the upper mantle are interpreted from lattice preferred orientations (LPO) produced experimentally in olivine, which depends on the dominant dislocation slip systems. At low pressure P<3 GPa, mantle temperature (T) and in dry conditions, olivine [100] dislocation slip dominates the less active [001] slip. This tends to align crystal fast velocity [100] axis with the principal shear direction. Yet recent high-pressure deformation experiments (Couvy et al., 2004, EJM, 16, 877; Raterron et al., 2007, Am. Min., 92, 1436; Raterron et al., 2008, Phys. Earth Planet. Int., doi:10.1016/j.pepi.2008.07.026) show that [001](010) slip system dominates [100](010) system in the (P,T) range of the deep upper mantle. This may promote a shear-parallel slow-velocity [001] axis and may explain the seismic-velocity attenuation observed at depth >200 km (Mainprice et al., 2005, Nature, 433, 731). In order to further constrain the effect of P on olivine slip system activities, which is classically quantified by the activation volume V* in power creep laws, deformation experiments were carried out in poor water condition, at P>5 GPa and T=1400°C, on pure forsterite (Fo100) and San Carlos olivine crystals, using the Deformation-DIA apparatus at the X17B2 beamline of the NSLS (Upton, NY). Ten crystals were oriented in order to active either [100] slip alone or [001] slip alone in (010) plane, or both [100](001) and [001](100) systems together. Constant applied stress σ <300 MPa and specimen strain rates were monitored in situ using time-resolved x-ray diffraction and radiography, respectively, for a total of 27 investigated steady state conditions. The obtained rheological data were compared with data previously obtained in comparable T and σ conditions, but at room P, by Darot and Gueguen (1981, JGR, 86, 6219) for Fo100 and by Bai et al. (1991, JGR, 96, 2441) for San Carlos olivine. This new set of data confirms previous deformation data

  5. A slow-slipping active fold and thrust system at the SE corner of the Atacama basin, northern Chile

    NASA Astrophysics Data System (ADS)

    Lin, Y.; Shyu, J. H.; González, G.

    2009-12-01

    The western South American offshore is one of the major active convergent plate boundaries in the world, where the Nazca plate is subducting northeastward beneath the South American plate at a rate of about 84 mm/yr. Despite of this rapid plate convergence, the forearc region of western Andes does not seem to undergo large deformation at present. In order to understand the characteristics and mechanisms of active forearc deformation related to the plate convergence, we investigated tectono-geomorphic features in the area of Tilocalar, near the SE margin of the Atacama Basin in northern Chile, where active structures have been previously identified. To map topographic features produced by active structures, we used a combination of several remote-sensing data sets, including digital elevation models (DEM) made from Shuttle Radar Topographic Mission (SRTM), as well as higher resolution ASTER and QuickBird satellite images. Detailed geomorphic surveys using real time kinematic (RTK) GPS are carried out in the field to obtain high-resolution topographic profiles across these features. We also performed 40Ar/39Ar dating of deformed volcanic rocks in order to determine the long-term slip rates of the active structures. The hyper-aridity of the Atacama Basin results in extremely low erosion and sedimentation rates in the area. As a result, the present relief of land surface is mostly produced by neotectonic activity, and can be used as deformation marker. In the Tilocalar area, several N-S trending ridges are present. These ridges, generally several tens of meters high, are likely formed by asymmetric anticlines or monoclines with steep forelimbs facing east, and these folds are likely fault-propagation folds produced by underlying thrust faults. We suggest that these faults merge at depth to become a major active thrust system. From 40Ar/39Ar plateau ages, we found that the surface ignimbrites mostly deposited in latest Pliocene (2.3~4.3 Ma). If the structures have been

  6. Olivine Slip-system Activity at High Pressure: Implications for Upper-Mantle Rheology and Seismic Anisotropy (Invited)

    NASA Astrophysics Data System (ADS)

    Raterron, P.; Castelnau, O.; Geenen, T.; Merkel, S.

    2013-12-01

    The past decade abounded in technical developments allowing the investigation of materials rheology at high pressure (P > 3 GPa) [1]. This had a significant impact on our understanding of olivine rheology in the Earth asthenosphere, where P is in the range 3 - 13 GPa. A dislocation slip-system transition induced by pressure has been documented in dry Fe-bearing olivine [2]; it induces changes in olivine aggregate lattice preferred orientation (LPO) [3,4], which may explain the seismic velocity anisotropy attenuation observed at depths > 200 km in the upper mantle [5]. Deformation experiments carried out on olivine single crystals at high pressure allowed quantifying the effect of P on individual slip system activities [6]. Integration of these data, together with data on lattice friction arising from computational models (e.g., [7]), into analytical or mean-field numerical models for aggregate plasticity gave insight on the viscosity and LPO of olivine aggregates deformed at geological conditions in the dislocation creep regime [8,9]. We will review these recent findings and their implications for upper mantle rheology and seismic anisotropy. [1] Raterron & Merkel, 2009, J. Sync. Rad., 16, 748 ; [2] Raterron et al., 2009, PEPI, 172, 74 ; [3] Jung et al., 2009, Nature Geoscience, 2, 73 ; [4] Ohuchi et al., 2011, EPSL, 304, 55 ; [5] Mainprice et al., 2005, Nature, 433, 731 ; [6] Raterron et al., 2012, PEPI, 200-201, 105 ; [7] Durinck et al., 2007, EJM, 19, 631 ; [8] Castelnau et al., 2010, C.R. Physique, 11, 304 ; [9] Raterron et al., 2011, PEPI, 188, 26

  7. Deformation textures in Fe{sub 3}Al alloys: An assessment of dominant slip system activity in the 900--1325 K temperature range of hot working

    SciTech Connect

    Kad, B.K.; Schoenfeld, S.E.; Asaro, R.J.; McKamey, C.G.; Sikka, V.K.

    1997-04-01

    A combination of numerical and experimental methodologies have been employed to study deformation textures in Fe{sub 3}Al alloys produced entirely by crystallographic shears on the <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace}, <100>{l_brace}011{r_brace} and <100>{l_brace}001{r_brace} slip systems, respectively. Numerical simulations indicate that both <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace} and <100>{l_brace}011{r_brace} slip systems produce a reasonably strong texture, while <100>{l_brace}001{r_brace} induces no texture over the initial random configuration. Experimental texture measurements on samples deformed at deformation rates of 10{sup {minus}3}--10{sup 1} s{sup {minus}1} by forging, rolling and extrusion in the 925--1325 K temperature range, of the B2 structure regime, agree well with the predicted textures for the <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace} slip system activation. These results appear to be in disagreement with prior transmission electron microscopy (TEM) observations that support the activation of <100>{l_brace}011{r_brace} and <100>{l_brace}001{r_brace} slip systems. Possible sources of discrepancies are elucidated. Finally, the loss of ductility in fully recrystallized microstructures is explained by textural reorganizations that are likely to impose larger normal stresses on the dominant {l_brace}100{r_brace} fracture planes.

  8. Determining the activation energies and slip systems for dislocation nucleation in body-centered cubic mo and face-centered cubic Ni single crystals

    SciTech Connect

    Wang, L.; Bei, Hongbin; Li, T.; Gao, Y. F.; George, Easo P; Nieh, T. G.

    2011-01-01

    Nanoindentation tests were performed on single crystals of Mo and Ni. The critical shear stress for the first pop-in was {approx}1/7 of the shear modulus in both crystals. The dependence of pop-in probability on load was understood in terms of a thermally activated dislocation nucleation process. Comparison of the activation energies suggests nucleation of full dislocations in Mo and partial dislocations in Ni. The activation energy analysis also offers information on the specific slip system on which dislocations are nucleated.

  9. Slip rates across the sinistral slip fault system of the Shan Plateau, northern SE Asia

    NASA Astrophysics Data System (ADS)

    Shi, X.; Sieh, K.; Wang, Y.; Liu, J.; Weldon, R. J.; Feng, L.; Chan, C. H.

    2014-12-01

    The sinistral-slip fault system of the Shan Plateau, arcing around the eastern Himalayan syntaxis and extending > 700 km from northwest to southeast, poses a high seismic hazard in northern SE Asia. Knowing slip rates and earthquake recurrence intervals of these faults is key to better quantification of that hazard. However, estimates of slip rates along the fault system remain poorly constrained. Here we report a preliminary estimate of the slip rate across the fault system from available campaign GPS velocities. We projected the horizontal GPS velocity vectors relative to the Sunda block reference frame perpendicular to the general strike (~ 240°) of the sinistral faults. The velocity profile shows a gradient of ~ 9 mm/yr over a distance of ~ 550 km that crosses 8 faults, from the Dayingjiang fault in the northwest to the Mengxing fault in the southeast. This suggests the average slip rate across each fault in the system is ~ 1 mm/yr. The 9 mm/yr of GPS velocity gradient across the fault system, however, is only half of the long-term rates determined from offsets of major rivers, ridges and plutons. These geological determinations suffer, however, from poor dating constraints. The discrepancy between the geodetic and geological analyses highlights the need of reliable constraints on slip rates along each of the faults. We have begun field work aimed at determining the slip rate of one of these, the Jinghong fault.

  10. Variations in strength and slip rate along the san andreas fault system.

    PubMed

    Jones, C H; Wesnousky, S G

    1992-04-01

    Convergence across the San Andreas fault (SAF) system is partitioned between strike-slip motion on the vertical SAF and oblique-slip motion on parallel dip-slip faults, as illustrated by the recent magnitude M(s) = 6.0 Palm Springs, M(s) = 6.7 Coalinga, and M(s) = 7.1 Loma Prieta earthquakes. If the partitioning of slip minimizes the work done against friction, the direction of slip during these recent earthquakes depends primarily on fault dip and indicates that the normal stress coefficient and frictional coefficient (micro) vary among the faults. Additionally, accounting for the active dip-slip faults reduces estimates of fault slip rates along the vertical trace of the SAF by about 50 percent in the Loma Prieta and 100 percent in the North Palm Springs segments. PMID:17802597

  11. Distribution of Slip at the Northern Sumatran Fault System

    NASA Technical Reports Server (NTRS)

    Genrich, J. F.; Bock, Y.; McCaffrey, R.; Prawirodirdjo, L.; Stevens, C. W.; Puntodewo, S. S. O.; Subarya, C.; Wdowinski, S.

    2000-01-01

    We model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989-1996 with the Global Positioning System (GPS) as elastic strain across a locked strike-slip fault to infer the contemporary slip rate, locking depth, and location of the Sumatran fault (SF) in northern Sumatra (1 S-3 N). GPS-derived slip rate estimates increase slightly northward from 23 plus or minus 3 mm/yr at 0.8 deg S to 26 plus or minus 2mm/yr at 2.7 N. They agree with geologic estimates north of the Equator, but at 0.5 S they are about 10 mm/yr higher. Strain appears to be distributed asymmetrically about the fault. South of 2 N, about 5 mm/yr of shear is required within the offshore forearc, west of the fault, to achieve a closer agreement of fault locations inferred from GPS velocities with geologically identified traces of the SF. Locking depth estimates are on the order of 10-20 km. The western branch of the major fault bifurcation near 1 N slips at a rate five times higher than the eastern branch. The two main strands of the fault at the northwestern tip of Sumatra (5.5 N) appear to be nearly free of horizontal strain; significant slip must occur away from the two strands, probably further east at two other geologically active branches. The Banda Aceh embayment is extruded to the northwest at a rate of 5 plus or minus 2 mm/yr. Within the estimated velocity uncertainties of several mm/yr, fault-normal deformation along the SF is insignificant. Almost strain free, the northern part of the back-arc basin is part of a rigid Sunda shelf, while the northern forearc is subjected to 8 plus or minus 5 x 10 (exp -8)/yr of extension nearly parallel to the arc.

  12. Deformation rates and localization of an active fault system in relation with rheological and frictional slip properties: The Corinth Rift case

    NASA Astrophysics Data System (ADS)

    El Arem, S.; Lyon-Caen, H.; Bernard, P.; Garaud, J. D.; Rolandone, F.; Briole, P.

    2012-04-01

    The Gulf of Corinth in Greece has attracted increasing attention because of its seismically active complex fault system and considerable seismic hazard. It is one of the most active extensional regions in the Mediterranean area. However, there are still open questions concerning the role and the geometry of the numerous active faults bordering the basin, as well as the mechanisms governing the seismicity. The Corinth Rift Laboratory (CRL http://crlab.eu) project is based on the cooperation of various European institutions that merge their efforts to study fault mechanics and related hazards in this natural laboratory with 10 destructive earthquakes per century (Magnitude > 6), among which 4 in the selected region of CRL. This active rift continues to open over 10-12 Km of width at a rate of 1:5 cm=yr. Most of the faults of the investigated area are in their latest part of cycle, so that the probability of at least one moderate to large earthquake (Magnitude = 6 to 6:7) is very high within a few decades. In the first part of this work, two-dimensional finite element models of a fault system is considered to estimate the effects of the crust rheological parameters on the stress distribution, the horizontal and vertical deformation in the vicinity of the faults, and the plastic deformation localization. We consider elasto-visco-plastic rheology with a power law viscosity for dislocation creep modelling and the Drucker-Prager yield criterion for plasticity. We investigate the rheological properties of the crust and examine their compatibility with both horizontal and vertical GPS observations recorded during campaigns conducted in the last twenty years. The second part is devoted to simulations involving rate and slip history friction laws for earthquake occurence prediction and seismogenic depth approximation. The case of a single fault is examined first, then two active faults are considered to highlight the effect of their interactions on the seismic cycle

  13. Exhumation and continental strike-slip fault systems: Introduction

    USGS Publications Warehouse

    Roeske, S.M.; Till, A.B.; Foster, D.A.; Sample, J.C.

    2007-01-01

    Metamorphic rocks adjacent to and within strike-slip faultsystems occur in a wide range of tectonic settings. Detailed studies show that for a number of these locales a significant part of the exhumation occurred during strike-slip fault motion, but the specific processes involved are often cryptic. Although some sites share characteristic features, such as metamorphic rocks exhumed in extensional step-overs within overall transtensional systems, no one common theme emerges from all of the studies. Our understanding of the variables that control continental strike-slip faults' interaction with mid- to lower-crustal structures is still primitive.

  14. Suppression of strike-slip fault systems

    NASA Astrophysics Data System (ADS)

    Curren, I. S.

    2012-12-01

    In orogens elongated parallel to a great circle about the Euler pole for the two bounding plates, theory requires simple-shear deformation in the form of distributed deformation or velocity discontinuities across strike-slip faults. This type of deformation, however, does not develop at all plate boundaries requiring toroidal motion. Using the global plate boundary model, PB2002 [Bird, 2003], as the basis for identifying areas where expected simple-shear deformation is absent or underdeveloped, it was also possible to identify two potential causes for this behavior: (1) the presence of extensive fracturing at right angles to the shear plane and (2) regional cover of flood basalts or andesites with columnar joints. To test this hypothesis, a new plane-stress finite-strain model was developed to study the effects of such pre-existing structures on the development of simple shear in a clay cake. A homogenous kaolinite-water mixture was poured into a deforming parallelogram box and partially dried to allow for brittle and plastic deformation at and below the surface of the clay, respectively. This was floated on a dense fluid foundation, effectively removing basal friction, and driven by a motor in a sinistral direction from the sides of the box. Control experiments produced classic Riedel model fault assemblages and discrete, through-going primary deformation zones (PDZs); experiments with pre-existing structures developed the same, though subdued and distributed, fault assemblages but did not develop through-going PDZs. Although formation of strike-slip faults was underdeveloped at the surface in clay with pre-existing structures, offset within the clay cake (measured, with respect to a fixed point, by markers on the clay surface) as a fraction of total offset of the box was consistently larger than that of the control experiments. This suggests that while the extent of surface faulting was lessened in clay with pre-existing structures, slip was still occurring at

  15. Spatial variations in late Quaternary slip rates along the Doruneh Fault System (Central Iran)

    NASA Astrophysics Data System (ADS)

    Farbod, Yassaman; Shabanian, Esmaeil; Bellier, Olivier; Abbassi, Mohammad Reza; Braucher, Régis; Benedetti, Lucilla; Bourlès, Didier; Hessami, Khaled

    2016-02-01

    The Doruneh Fault System (DFS) is one of the major active strike-slip faults in the Arabia-Eurasia collision zone. Despite its geological activity, no large (M ≥ 6.5) historical or instrumental earthquakes have been recorded along it. To date, the rate and distribution of slip, as well as the seismic behavior of the DFS, have been unknown. We reconstructed 67 geomorphic offsets recorded by three successive alluvial abandonment surfaces (Q1, Q2, and Q3) displaced along the western (WFZ) and central (CFZ) fault zones. The determined ages of ~12, ~36, and ~120 ka, using in situ-produced 10Be and 36Cl cosmogenic nuclides for theses surfaces, allowed to estimate three sets of individual left-lateral slip rates and consequently to describe the spatiotemporal distribution of slip along the CFZ and WFZ. The slip rates averaged over time intervals of ~36 and ~120 ka reveal variable slip rates along length but similar slip rates at a point with a maximum rate of ~8.2 mm/yr. During the Holocene, however, the fault slip behavior appears more complex, with a maximum rate of ~5.3 mm/yr. The CFZ is divided into two ~4 km apart segments, with symmetrical slip distributions relative to a persistent boundary, which has not been ruptured over the last ~12 ka. The maximum length of seismic fault segments varies from 70 to 100 km, which could produce earthquakes with a magnitude of Mw 7.2-7.4. This emphasizes the necessity of segmentation models for long strike-slip faults that may not necessarily rupture along their whole length during a single earthquake.

  16. Pressure-Induced Slip-System Transition in Forsterite: Single-Crystal Rheological Properties at Mantle Pressure and Temperature

    SciTech Connect

    Raterron,P.; Chen, J.; Li, L.; Weidner, D.; Cordier, P.

    2007-01-01

    Deformation experiments were carried out in a Deformation-DIA high-pressure apparatus (D-DIA) on oriented Mg2SiO4 olivine (Fo100) single crystals, at pressure (P) ranging from 2.1 to 7.5 GPa, in the temperature (T) range 1373-1677 K, and in dry conditions. These experiments were designed to investigate the effect of pressure on olivine dislocation slip-system activities, responsible for the lattice-preferred orientations observed in the upper mantle. Two compression directions were tested, promoting either [100] slip alone or [001] slip alone in (010) crystallographic plane. Constant applied stress ({sigma}) and specimen strain rates (Formula) were monitored in situ using time-resolved X-ray synchrotron diffraction and radiography, respectively. Transmission electron microscopy (TEM) investigation of the run products reveals that dislocation creep assisted by dislocation climb and cross slip was responsible for sample deformation. A slip transition with increasing pressure, from a dominant [100]-slip to a dominant [001]-slip, is documented. Extrapolation of the obtained rheological laws to upper-mantle P, T, and {sigma} conditions, suggests that [001]-slip activity becomes comparable to [100]-slip activity in the deep upper mantle, while [001] slip is mostly dominant in subduction zones. These results provide alternative explanations for the seismic anisotropy attenuation observed in the upper mantle, and for the 'puzzling' seismic-anisotropy anomalies commonly observed in subduction zones.

  17. Formation and Suppression of Strike-Slip Fault Systems

    NASA Astrophysics Data System (ADS)

    Curren, Ivy S.; Bird, Peter

    2014-11-01

    Strike-slip faults are a defining feature of plate tectonics, yet many aspects of their development and evolution remain unresolved. For intact materials and/or regions, a standard sequence of shear development is predicted from physical models and field studies, commencing with the formation of Riedel shears and culminating with the development of a throughgoing fault. However, for materials and/or regions that contain crustal heterogeneities (normal and/or thrust faults, joints, etc.) that predate shear deformation, kinematic evolution of strike-slip faulting is poorly constrained. We present a new plane-stress finite-strain physical analog model developed to investigate primary deformation zone evolution in simple shear, pure strike-slip fault systems in which faults or joints are present before shear initiation. Experimental results suggest that preexisting mechanical discontinuities (faults and/or joints) have a marked effect on the geometry of such systems, causing deflection, lateral distribution, and suppression of shears. A lower limit is placed on shear offset necessary to produce a throughgoing fault in systems containing preexisting structures. Fault zone development observed in these experiments provides new insight for kinematic interpretation of structural data from strike-slip fault zones on Earth, Venus, and other terrestrial bodies.

  18. Quaternary slip-rates of the Kazerun and the Main Recent Faults: active strike-slip partitioning in the Zagros fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Authemayou, Christine; Bellier, Olivier; Chardon, Dominique; Benedetti, Lucilla; Malekzade, Zaman; Claude, Christelle; Angeletti, Bernard; Shabanian, Esmaeil; Abbassi, Mohammad Reza

    2009-07-01

    The aim of this work is to constrain the Late Quaternary activity of two major dextral strike-slip faults of the Zagros fold-and-thrust belt of Southern Iran, within the framework of right-oblique convergence between Arabia and Eurasia. The NW-trending Main Recent fault marks the rear of the belt along two thirds of its length. Its southeastern tip connects to the northern termination of the N-trending Kazerun Fault, which affects the entire width of the belt. Horizontal slip rates have been estimated on these two faults over the last 140 ka from lateral offsets of streams and fans and in situ cosmogenic 36Cl exposure dating of cobbles sampled on the surface of these geomorphic features. Compared to GPS data, the obtained minimum slip rate of 3.5-12.5 mm yr-1 on the Main Recent Fault implies strike-slip partitioning of the convergence along this fault. Minimum slip rate of the Kazerun Fault is 2.5-4 mm yr-1 for its northern strand, 1.5-3.5 mm yr-1 for its central segment and is negligible for its southern segment. These results are consistent with southward distribution of the slip from along the Main Recent Fault to the longitudinal thrusts and folds of the fold-and-thrust belt through the Kazerun Fault, with a decrease of slip from the southeastern tip of the Main Recent Fault towards the southern termination of the Kazerun Fault. The Kazerun and associated faults form the horsetail termination of the Main Recent fault and may be seen as the propagating southeastern front of the fault system that accommodates indentation of Eurasia by Arabia.

  19. Slip distribution, strain accumulation and aseismic slip on the Chaman Fault system

    NASA Astrophysics Data System (ADS)

    Amelug, F.

    2015-12-01

    The Chaman fault system is a transcurrent fault system developed due to the oblique convergence of the India and Eurasia plates in the western boundary of the India plate. To evaluate the contemporary rates of strain accumulation along and across the Chaman Fault system, we use 2003-2011 Envisat SAR imagery and InSAR time-series methods to obtain a ground velocity field in radar line-of-sight (LOS) direction. We correct the InSAR data for different sources of systematic biases including the phase unwrapping errors, local oscillator drift, topographic residuals and stratified tropospheric delay and evaluate the uncertainty due to the residual delay using time-series of MODIS observations of precipitable water vapor. The InSAR velocity field and modeling demonstrates the distribution of deformation across the Chaman fault system. In the central Chaman fault system, the InSAR velocity shows clear strain localization on the Chaman and Ghazaband faults and modeling suggests a total slip rate of ~24 mm/yr distributed on the two faults with rates of 8 and 16 mm/yr, respectively corresponding to the 80% of the total ~3 cm/yr plate motion between India and Eurasia at these latitudes and consistent with the kinematic models which have predicted a slip rate of ~17-24 mm/yr for the Chaman Fault. In the northern Chaman fault system (north of 30.5N), ~6 mm/yr of the relative plate motion is accommodated across Chaman fault. North of 30.5 N where the topographic expression of the Ghazaband fault vanishes, its slip does not transfer to the Chaman fault but rather distributes among different faults in the Kirthar range and Sulaiman lobe. Observed surface creep on the southern Chaman fault between Nushki and north of City of Chaman, indicates that the fault is partially locked, consistent with the recorded M<7 earthquakes in last century on this segment. The Chaman fault between north of the City of Chaman to North of Kabul, does not show an increase in the rate of strain

  20. Airborne Antenna System for Minimum-Cycle-Slip GPS Reception

    NASA Technical Reports Server (NTRS)

    Wright, C. Wayne

    2009-01-01

    A system that includes a Global Positioning System (GPS) antenna and associated apparatus for keeping the antenna aimed upward has been developed for use aboard a remote-sensing-survey airplane. The purpose served by the system is to enable minimum- cycle-slip reception of GPS signals used in precise computation of the trajectory of the airplane, without having to restrict the airplane to maneuvers that increase the flight time needed to perform a survey. Cycle slip signifies loss of continuous track of the phase of a signal. Minimum-cycle-slip reception is desirable because maintaining constant track of the phase of the carrier signal from each available GPS satellite is necessary for surveying to centimeter or subcentimeter precision. Even a loss of signal for as short a time as a nanosecond can cause cycle slip. Cycle slips degrade the quality and precision of survey data acquired during a flight. The two principal causes of cycle slip are weakness of signals and multipath propagation. Heretofore, it has been standard practice to mount a GPS antenna rigidly on top of an airplane, and the radiation pattern of the antenna is typically hemispherical, so that all GPS satellites above the horizon are viewed by the antenna during level flight. When the airplane must be banked for a turn or other maneuver, the reception hemisphere becomes correspondingly tilted; hence, the antenna no longer views satellites that may still be above the Earth horizon but are now below the equatorial plane of the tilted reception hemisphere. Moreover, part of the reception hemisphere (typically, on the inside of a turn) becomes pointed toward ground, with a consequent increase in received noise and, therefore, degradation of GPS measurements. To minimize the likelihood of loss of signal and cycle slip, bank angles of remote-sensing survey airplanes have generally been limited to 10 or less, resulting in skidding or slipping uncoordinated turns. An airplane must be banked in order to make

  1. Slip stream apparatus and method for treating water in a circulating water system

    DOEpatents

    Cleveland, Joe R.

    1997-01-01

    An apparatus (10) for treating water in a circulating water system (12) t has a cooling water basin (14) includes a slip stream conduit (16) in flow communication with the circulating water system (12), a source (36) of acid solution in flow communication with the slip stream conduit (16), and a decarbonator (58) in flow communication with the slip stream conduit (16) and the cooling water basin (14). In use, a slip stream of circulating water is drawn from the circulating water system (12) into the slip stream conduit (16) of the apparatus (10). The slip stream pH is lowered by contact with an acid solution provided from the source (36) thereof. The slip stream is then passed through a decarbonator (58) to form a treated slip stream, and the treated slip stream is returned to the cooling water basin (14).

  2. Slip stream apparatus and method for treating water in a circulating water system

    DOEpatents

    Cleveland, J.R.

    1997-03-18

    An apparatus is described for treating water in a circulating water system that has a cooling water basin which includes a slip stream conduit in flow communication with the circulating water system, a source of acid solution in flow communication with the slip stream conduit, and a decarbonator in flow communication with the slip stream conduit and the cooling water basin. In use, a slip stream of circulating water is drawn from the circulating water system into the slip stream conduit of the apparatus. The slip stream pH is lowered by contact with an acid solution provided from the source thereof. The slip stream is then passed through a decarbonator to form a treated slip stream, and the treated slip stream is returned to the cooling water basin. 4 figs.

  3. Interaction between slip events, erosion and sedimentation along an active strike-slip fault: Insights from analog models

    NASA Astrophysics Data System (ADS)

    Chatton, M.; Malavieille, J.; Dominguez, S.; Manighetti, I.; Romano, C.; Beauprêtre, S.; Garembois, S.; Larroque, C.

    2012-04-01

    device is indeed coupled with a rainfall system, while an optical measurement apparatus that includes digital cameras and a laser interferometer, allows observing and measuring continuously at very high resolution the evolution of the model surface morphology. The analog material is a mix of granular materials -glass microbeads, silica powder and plastic powder saturated in water, whose mass composition and, consequently, mechanical properties lead to a geometric scaling of about 1:10 000 and to a temporal scaling on the order of one second equivalent to a few dozens of years. The protocol allows monitoring together the evolution of the fault and that of the morphological markers that the fault progressively offsets as slip events are imposed. We have conducted several experiences in different settings and we will present the preliminary results that we have obtained. We basically could survey the formation and evolution of a strike-slip fault from its immature stages up to one hundred repeated slip events. Under the combined effects of accumulating slip, erosion and sedimentation, the model surface exhibits tectonic and morphological structures similar to natural features (Riedel's shears, pressure and shutter ridges, pull-apart basins, alluvial fans, terrace risers, braided rivers, etc), whose space and time evolution can be precisely analyzed. Deformation partitioning, sequential formation of alluvial terraces, stream captures, development of 'traps' filling with sediments, etc, are especially observed. The control on the imposed amplitude and frequency of the rainfall cycles allows us to examine the impact of these rainfalls on the fault morphology and the evolution of the associated morphological markers. Finally, we can compare the imposed slip events (number, amplitudes, repeat times) with the cumulative offsets eventually visible and measurable at the model surface. Marked discrepancies are found between imposed and final apparent offsets that shed light on the

  4. Slip sense inversion on active strike-slip faults in southwest Japan and its implications for Cenozoic tectonic evolution

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2004-05-01

    Analyses of deflected river channels, offset of basement rocks, and fault rock structures reveal that slip sense inversion occurred on major active strike-slip faults in southwest Japan such as the Yamasaki and Mitoke fault zones and the Median Tectonic Line (MTL). Along the Yamasaki and Mitoke fault zones, small-size rivers cutting shallowly mountain slopes and Quaternary terraces have been deflected sinistrally, whereas large-size rivers which deeply incised into the Mio-Pliocene elevated peneplains show no systematically sinistral offset or complicated hairpin-shaped deflection. When the sinistral offsets accumulated on the small-size rivers are restored, the large-size rivers show residual dextral deflections. This dextral offset sense is consistent with that recorded in the pre-Cenozoic basement rocks. S-C fabrics of fault gouge and breccia zone developed in the active fault zones show sinistral shear sense compatible with earthquake focal mechanisms, whereas those of the foliated cataclasite indicate a dextral shear sense. These observations show that the sinistral strike-slip shear fabrics were overprinted on dextral ones which formed during a previous deformation phase. Similar topographic and geologic features are observed along the MTL in the central-eastern part of the Kii Peninsula. Based on these geomorphological and geological data, we infer that the slip sense inversion occurred in the period between the late Tertiary and mid-Quaternary period. This strike-slip inversion might result from the plate rearrangement consequent to the mid-Miocene Japan Sea opening event. This multidisciplinary study gives insight into how active strike-slip fault might evolves with time.

  5. A simplified method for determining the number of independent slip systems in crystals

    NASA Technical Reports Server (NTRS)

    Cotton, J. D.; Kaufman, M. J.; Noebe, R. D.

    1991-01-01

    A novel method for determining the number of independent slip systems for any family or a combination of families of slip systems is proposed, which is more direct than previous approaches. This technique makes it possible to easily determine, from the known operative slip systems, if the material is slip-system-deficient. The method also makes it possible to determine if twinning may contribute additional deformation modes.

  6. Kinematically Coupled Strike-Slip and Normal Faults in the Lake Mead Strike-Slip Fault System, Southeast Nevada

    NASA Astrophysics Data System (ADS)

    Kattenhorn, S. A.; Marshall, S. T.; Cooke, M. L.

    2008-12-01

    The Lake Mead fault system consists of a ~95 km long, northeast-trending zone of strike-slip faults of Miocene age that accommodate a total left-lateral offset of 20-65 km. We use a combination of detailed field mapping and numerical modeling to show that a previously unnamed left-lateral strike-slip segment of the Lake Mead fault system and a dense cluster of dominantly west-dipping normal faults acted in concert to accommodate regional left-lateral offset. We suggest that the strike-slip fault that we refer to as the Pinto Ridge fault: (1) was kinematically related to other faults of the Lake Mead fault system; (2) was responsible for the creation of the normal fault cluster at Pinto Ridge; and (3) utilized these normal faults as linking structures between separate strike-slip fault segments to create a longer, through-going fault. Results from numerical models demonstrate that the observed location and curving strike patterns of the normal fault cluster is consistent with the faults having formed as secondary structures as the result of the perturbed stress field around the slipping Pinto Ridge fault. Comparison of mechanical efficiency of various normal fault geometries within extending terranes suggests that the observed west dip of normal faults reflects a west- dipping anisotropy at depth, such as a detachment. The apparent terminations of numerous strike-slip faults of the Lake Mead fault system into west-dipping normal faults suggest that a west-dipping detachment may be regionally coherent.

  7. Transpressional segment boundaries in strike-slip fault systems offshore southern California: Implications for fluid expulsion and cold seep habitats

    NASA Astrophysics Data System (ADS)

    Maloney, Jillian M.; Grupe, Benjamin M.; Pasulka, Alexis L.; Dawson, Katherine S.; Case, David H.; Frieder, Christina A.; Levin, Lisa A.; Driscoll, Neal W.

    2015-05-01

    The importance of tectonics and fluid flow in controlling cold seep habitats has long been appreciated at convergent margins but remains poorly understood in strike-slip systems. Here we present geophysical, geochemical, and biological data from an active methane seep offshore from Del Mar, California, in the inner California borderlands (ICB). The location of this seep appears controlled by localized transpression associated with a step in the San Diego Trough fault zone and provides an opportunity to examine the interplay between fluid expulsion and restraining step overs along strike-slip fault systems. These segment boundaries may have important controls on seep locations in the ICB and other margins characterized by strike-slip faulting (e.g., Greece, Sea of Marmara, and Caribbean). The strike-slip fault systems offshore southern California appear to have a limited distribution of seep sites compared to a wider distribution at convergent plate boundaries, which may influence seep habitat diversity and connectivity.

  8. Transformations in shallow fault zones; evidence from fault rocks in young strike-slip systems.

    NASA Astrophysics Data System (ADS)

    van der Pluijm, B. A.; Schleicher, A. M.; Warr, L. N.

    2008-12-01

    cataclasis creates nucleation sites for neomineralization or produces localized melting in upper-crustal strike-slip fault systems (< 5 km depth), which is coupled to slip rate. Transformations in shallow fault rock involve the localization of clay neomineralization along slip surfaces in creeping segments, controlling strength in the shallowest segment of fault zones. During sudden, large displacements, the energy can be sufficient to produce friction melts that are similarly generated at small slip surfaces. Thus, shallow faults rocks preserve mineral and state transformations during faulting, and provide information on the history of fluid activity, mass transport and mechanical behavior. Additionally, dating of neocrystallized mineral phases by radiogenic techniques provides the age of faulting and can constrain rates of crustal deformation.

  9. Relative tectonic activity assessment along the East Anatolian strike-slip fault, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Khalifa, Abdelrahman

    2016-04-01

    The East Anatolian transform fault is a morphologically distinct and seismically active left-lateral strike-slip fault that extends for ~ 500 km from Karlıova to the Maraş defining the boundary between the Anatolian Block and Syrian Foreland. Deformed landforms along the East Anatolian fault provide important insights into the nature of landscape development within an intra-continental strike-slip fault system. Geomorphic analysis of the East Anatolian fault using geomorphic indices including mountain front sinuosity, stream length-gradient index, drainage density, hypsometric integral, and the valley-width to valley height ratio helped differentiate the faulting into segments of differing degrees of the tectonic and geomorphic activity. Watershed maps for the East Anatolian fault showing the relative relief, incision, and maturity of basins along the fault zone help define segments of the higher seismic risk and help evaluate the regional seismic hazard. The results of the geomorphic indices show a high degree of activity, reveal each segment along the fault is active and represent a higher seismic hazard along the entire fault.

  10. Investigation of Three-Dimensional Stress Fields and Slip Systems for FCC Single Crystal Superalloy Notched Specimens

    NASA Technical Reports Server (NTRS)

    Arakere, Nagaraj K.; Magnan, Shannon; Ebrahimi, Fereshteh; Ferroro, Luis

    2004-01-01

    Metals and their alloys, except for a few intermetallics, are inherently ductile, i.e. plastic deformation precedes fracture in these materials. Therefore, resistance to fracture is directly related to the development of the plastic zone at the crack tip. Recent studies indicate that the fracture toughness of single crystals depends on the crystallographic orientation of the notch as well as the loading direction. In general, the dependence of crack propagation resistance on crystallographic orientation arises from the anisotropy of (i) elastic constants, (ii) plastic deformation (or slip), and (iii) the weakest fracture planes (e.g. cleavage planes). Because of the triaxial stress state at the notch tips, many slip systems that otherwise would not be activated during uniaxial testing, become operational. The plastic zone formation in single crystals has been tackled theoretically by Rice and his co-workers and only limited experimental work has been conducted in this area. The study of the stresses and strains in the vicinity of a FCC single crystal notch tip is of relatively recent origin. We present experimental and numerical investigation of 3D stress fields and evolution of slip sector boundaries near notches in FCC single crystal tension test specimens, and demonstrate that a 3D linear elastic finite element model that includes the effect of material anisotropy is shown to predict active slip planes and sectors accurately. The slip sector boundaries are shown to have complex curved shapes with several slip systems active simultaneously near the notch. Results are presented for surface and mid-plane of the specimens. The results demonstrate that accounting for 3D elastic anisotropy is very important for accurate prediction of slip activation near FCC single crystal notches loaded in tension. Results from the study will help establish guidelines for fatigue damage near single crystal notches.

  11. Three-Dimensional Stress Fields and Slip Systems for Single Crystal Superalloy Notched Specimens

    NASA Technical Reports Server (NTRS)

    Magnan, Shannon M.; Throckmorton, David (Technical Monitor)

    2002-01-01

    Single crystal superalloys have become increasingly popular for turbine blade and vane applications due to their high strength, and creep and fatigue resistance at elevated temperatures. The crystallographic orientation of a single crystal material greatly affects its material properties, including elastic modulus, shear modulus, and ductility. These directional properties, along with the type of loading and temperature, dictate an anisotropic response in the yield strength, creep resistance, creep rupture ductility, fatigue resistance, etc. A significant amount of research has been conducted to determine the material properties in the <001> orientation, yet the material properties deviating from the <001> orientation have not been assessed for all cases. Based on the desired application and design criteria, a crystal orientation is selected to yield the maximum properties. Currently, single crystal manufacturing is able to control the primary crystallographic orientation within 15 of the target orientation, which is an acceptable deviation to meet both performance and cost guidelines; the secondary orientation is rarely specified. A common experiment is the standard load-controlled tensile test, in which specimens with different orientations can be loaded to observe the material response. The deformation behavior of single-crystal materials under tension and compression is known to be a function of not only material orientation, but also of varying microdeformation (i.e. dislocation) mechanisms. The underlying dislocation motion causes deformation via slip, and affects the activation of specific slip systems based on load and orientation. The slip can be analyzed by observing the visible traces left on the surface of the specimen from the slip activity within the single crystal material. The goal of this thesis was to predict the slip systems activated in three-dimensional stress fields of a notched tensile specimen, as a function of crystal orientation, using

  12. Analysis of slip activity and heterogeneous deformation in tension and tension-creep of Ti-5Al-2.5Sn (wt %) using in-situ SEM experiments

    NASA Astrophysics Data System (ADS)

    Li, H.; Boehlert, C. J.; Bieler, T. R.; Crimp, M. A.

    2012-08-01

    The deformation behavior of a Ti-5Al-2.5Sn (wt %) near-α alloy was investigated during in-situ deformation inside a scanning electron microscope. Tensile experiments were performed at 296 K and 728 K (≈0.4 T m), while tensile-creep experiments were performed at 728 K and 763 K. Active deformation systems were identified using electron backscattered diffraction-based slip trace analysis. Both basal and prismatic slip systems were active during the tensile experiments. Basal slip was observed for grains clustered around high Schmid factor orientations, while prismatic slip exhibited less dependence on the crystallographic orientation. The tension-creep experiments revealed less slip but more development of grain boundary ledges than in the higher strain rate tensile experiments. Some of the grain boundary ledges evolved into grain boundary cracks, and grain boundaries oriented nearly perpendicular to the tensile axis formed ledges earlier in the deformation process. Grain boundaries with high misorientations also tended to form ledges earlier than those with lower misorientations. Most of the grain boundary cracks formed in association with grains displaying hard orientations, where the c-axis was nearly perpendicular to the tensile direction. For the tension-creep experiments, pronounced basal slip was observed in the lower-stress creep regime and the activity of prismatic slip increased with increasing creep stress and temperature.

  13. Refining estimates of Quaternary slip on the Karakoram Fault System, Ladakh, NW India

    NASA Astrophysics Data System (ADS)

    Bohon, W.; Arrowsmith, R.; Hodges, K. V.; Heimsath, A. M.

    2013-12-01

    The NW-SE striking, dextral Karakoram fault system (KFS) stretches for more than 1200 km from the Pamirs of Central Asia at least as far southeast as the Kailas area of Tibet. It is one of the major tectonic features in the Himalayan orogen, yet considerable controversy remains about the time-integrated slip rate of the system. Geodetic data suggest present-day motion along the entire KFS occurs at 1-3 mm/yr (Wright et al., 2004, Science 305; Jade et al., 2010, GSA 116), but estimates for the integrated late Quaternary slip along various segments of the system - based on the reconstruction of dated, offset geomorphic and geologic features - range from ca. 4 mm/yr to ca. 32 mm/yr (Liu et al., 1991 in Avouac and Tapponier, 1993, GRL 20; Brown et al., 2002, JGR 107; Chevalier et al., 2005, Science 307). In the Ladakh region of NW India (34°45.27'N, 77°33.57'E), the KFS expresses as northern ('Pangong') and southern ('Tangtse') strands bounding the Pangong Range. The lack of documented Quaternary offset along the southern fault strand has led most researchers to assume that Quaternary slip on the KFS in this region was partitioned exclusively to the northern fault strand (Searle, 1998, Geological Society [London] Special Publication 135; Phillips et al., 2004, EPSL 226; Rutter et al., 2007, Journal of Structural Geology 29). However, our more recent field work in the northwestern Pangong Range has documented significant Quaternary activity along the Tangtse fault strand. Along this strand in the Tangyar Valley (34°14.26'N, 77°55.05'E), an incised debris cone has erosional risers offset ~160 m right laterally and ~25 m vertically (east side up) which is consistent with the dextral-oblique transpressional sense of motion for the KFS in this region. 10Be concentration depth profiles yield a preliminary minimum exposure age of ~30,000 yrs for the offset debris fan surfaces, which provides a maximum slip rate of ~5 mm/yr. Adjacent to the debris cone is a lower and

  14. Earthquake cycle associated with active strike slip faults in central Panamá

    NASA Astrophysics Data System (ADS)

    Rick, Bennett; Spinler, Joshua C.; Compton, Kathleen; Rockwell, Thomas K.; Gath, Eldon

    2013-04-01

    The rigidity of the Panamá Isthmus is currently under debate, with important implications for seismic hazards to the Panamá Canal and Panamá City. Whereas Panamá has traditionally been described as a non-deforming microplate caught between a number of larger tectonic plates, new paleoseismic data collected at a limited number of trench sites in association with the ongoing expansion of the Panamá Canal may challenge the validity of the rigid microplate hypothesis. Crustal velocities from a new, ~100 km aperture, 5-station continuous GPS network constructed across the Rio Gatún, Limón, and Pedro Miguel fault zones confirm that these fault zones are active, forming a system of faults that traverse central Panamá in close proximity to the Panamá Canal and Panamá City. However, the slip rates inferred from these new geodetic data are lower than the geologic rates when using an elastic halfspace model. Differences among previous geodetic investigations, which concluded that Panamá is rigid, and the geological slip rate estimates are explained by earthquake cycle effects associated with long recurrence intervals relative to lower crust and upper mantle Maxwell relaxation times. Late in the earthquake cycle the geodetic strain field is broadly distributed, giving the false appearance of low seismic hazards.

  15. Insights on activation enthalpy for non-Schmid slip in body-centered cubic metals

    SciTech Connect

    Hale, Lucas M.; Lim, Hojun; Zimmerman, Jonathan A.; Battaile, Corbett C.; Weinberger, Christopher R.

    2014-12-18

    We use insights gained from atomistic simulation to develop an activation enthalpy model for dislocation slip in body-centered cubic iron. Furthermore, using a classical potential that predicts dislocation core stabilities consistent with ab initio predictions, we quantify the non-Schmid stress-dependent effects of slip. The kink-pair activation enthalpy is evaluated and a model is identified as a function of the general stress state. Thus, our model enlarges the applicability of the classic Kocks activation enthalpy model to materials with non-Schmid behavior.

  16. Solute effect on basal and prismatic slip systems of Mg.

    PubMed

    Moitra, Amitava; Kim, Seong-Gon; Horstemeyer, M F

    2014-11-01

    In an effort to design novel magnesium (Mg) alloys with high ductility, we present a first principles data based on the Density Functional Theory (DFT). The DFT was employed to calculate the generalized stacking fault energy curves, which can be used in the generalized Peierls-Nabarro (PN) model to study the energetics of basal slip and prismatic slip in Mg with and without solutes to calculate continuum scale dislocation core widths, stacking fault widths and Peierls stresses. The generalized stacking fault energy curves for pure Mg agreed well with other DFT calculations. Solute effects on these curves were calculated for nine alloying elements, namely Al, Ca, Ce, Gd, Li, Si, Sn, Zn and Zr, which allowed the strength and ductility to be qualitatively estimated based on the basal dislocation properties. Based on our multiscale methodology, a suggestion has been made to improve Mg formability. PMID:25273695

  17. Slip compensation at fault damage zones along earthquake surface ruptures

    NASA Astrophysics Data System (ADS)

    Choi, J.; Kim, Y.

    2013-12-01

    to those of the main traces. In contrast, when the L/W < 2, the vertical slip is either increased or decreased as the horizontal slip is decreased, depending on the maturity of the linking zone. Thus, we argue that slip patterns at linking damage zones may be controlled by the LW-ratio of linking damage zones and hence structural maturities of the segmented fault systems. In conclusion, slip patterns at fault damage zones along earthquake surface ruptures are various depending on the maturity of linkage zones and/or the rupture propagation direction. Therefore, the consideration of slip compensation as well as damage structures along surface ruptures must be very useful to understand fault evolution and, hence, to assess seismic hazards around active fault systems.

  18. Strike-slip structural styles and petroleum system evolution, northeast Sakhalin Island

    SciTech Connect

    Meisling, K.E.; Wagner, J.B.

    1996-12-31

    The primary petroleum system of northeast Sakhalin Island and adjacent shelfal areas is comprised of a system of Late Miocene to Quaternary faulted transpressional anticlines that trap oil and gas in Early Miocene to Pliocene deltaic reservoirs sourced from Late Oligocene to Early Miocene diatomaceous shales. Existing production has been limited to onshore anticlines, and offshore structural trends remain undeveloped, despite several discoveries. The regional tectonic evolution of Sakhalin Island can be divided into five major phases: (1) Late Cretaceous to Early Eocene subduction, (2) Middle-Eocene collision and uplift, (3) Late Eocene to Early Oligocene oblique rifting, (4) Late Oligocene to Middle Miocene thermal subsidence, and (5) Late Miocene to Quaternary transpression and inversion. Oil-prone source rocks were deposited during rapid post-rift thermal subsidence of transtensional rift basins and adjacent highs, which provided an ideal sediment-starved setting for source rock accumulation. Reservoir facies were supplied by prograding post-rift Miocene deltaics of the paleo-Amur river, which built a shelf across the thermally subsiding basin and intrabasin highs. Traps were formed when the basin was later inverted during Late Miocene to Pleistocene transpression, which reactivated both Paleogene normal faults and structural trends of the Mesozoic accretionary prism to create a broad zone of distributed shear. Strike-slip structural styles are evidenced by linear, en echelon alignments of doubly-plunging anticlines characterized by numerous small-displacement, transverse normal faults. Strike slip on individual structures is relatively small, however, based on a lack of thorough going faults. Strike-slip structures on Sakhalin Island are considered active, in light of the earthquake of May 27, 1995 (M=7.6) and uplift of Pleistocene marine terraces.

  19. Strike-slip structural styles and petroleum system evolution, northeast Sakhalin Island

    SciTech Connect

    Meisling, K.E.; Wagner, J.B. )

    1996-01-01

    The primary petroleum system of northeast Sakhalin Island and adjacent shelfal areas is comprised of a system of Late Miocene to Quaternary faulted transpressional anticlines that trap oil and gas in Early Miocene to Pliocene deltaic reservoirs sourced from Late Oligocene to Early Miocene diatomaceous shales. Existing production has been limited to onshore anticlines, and offshore structural trends remain undeveloped, despite several discoveries. The regional tectonic evolution of Sakhalin Island can be divided into five major phases: (1) Late Cretaceous to Early Eocene subduction, (2) Middle-Eocene collision and uplift, (3) Late Eocene to Early Oligocene oblique rifting, (4) Late Oligocene to Middle Miocene thermal subsidence, and (5) Late Miocene to Quaternary transpression and inversion. Oil-prone source rocks were deposited during rapid post-rift thermal subsidence of transtensional rift basins and adjacent highs, which provided an ideal sediment-starved setting for source rock accumulation. Reservoir facies were supplied by prograding post-rift Miocene deltaics of the paleo-Amur river, which built a shelf across the thermally subsiding basin and intrabasin highs. Traps were formed when the basin was later inverted during Late Miocene to Pleistocene transpression, which reactivated both Paleogene normal faults and structural trends of the Mesozoic accretionary prism to create a broad zone of distributed shear. Strike-slip structural styles are evidenced by linear, en echelon alignments of doubly-plunging anticlines characterized by numerous small-displacement, transverse normal faults. Strike slip on individual structures is relatively small, however, based on a lack of thorough going faults. Strike-slip structures on Sakhalin Island are considered active, in light of the earthquake of May 27, 1995 (M=7.6) and uplift of Pleistocene marine terraces.

  20. Investigating Fault Slip Budget in the Cocos Subducting Plate from Characteristically Repeating Earthquake Activity

    NASA Astrophysics Data System (ADS)

    Dominguez, L. A.; Taira, T.

    2013-12-01

    High-quality seismic and geodetic data from dense networks have revealed that the Cocos subducting plate in the Mesoamerican region has been experienced a rich variety of transient slip including earthquakes, slow slip events, and tectonic tremors. Detecting these transient deformation fields with estimations in the locations of responsible deformation areas is a fundamental first step in addressing the slip budget in the Mesoamerican region. We search for characteristically repenting earthquakes (CREs) in the Cocos subducting plate in the Mesoamerican region, by analyzing over 30 years of historical seismic data collected by the National Seismological Service (SSN). Spatiotemporal properties in the CRE activity would allow us to infer aseismic slip surrounding the CRE sequences. The seismic signatures in our target area show a remarkable resemblance to zones where repeating earthquakes have been previously identified. Namely, the flat segment of subducting slab shows a strongly couple zone followed wide creeping zone that extends up to ~250km inland. Our preliminary search for CREs was limited to analyze broadband seismic data (with a 1-8 Hz bandpass filter) recorded at two stations, we however identify a few candidate CRE sequences with a cross-correlation threshold of 0.90. We will extend our analysis to data collected from other stations and to examine smaller earthquakes to detect additional CREs and will evaluate aseismic slip rates from the identified CRE sequences.

  1. Strike-slip faulting and block rotation in the Lake Mead fault system

    NASA Astrophysics Data System (ADS)

    Ron, Hagai; Aydin, Atilla; Nur, Amos

    1986-12-01

    Strike-slip faults in the Basin and Range province have often been considered passive boundaries between differentially extended domains of tilted normal faults and are thus considered secondary in accommodating regional horizontal deformation. Paleomagnotic investigation of late Miocene age volcanic rocks, displaced by the left-lateral fault system of Lake Mead, Nevada, shows: (1) that these rocks have not been affected by significant structural tilt, the difference between observed and expected inclinations being only -0.6° ± 14.9° and (2) a significant horizontal counterclockwise rotation of -29.4° ± 8.5° about a vertical axis. This rotation was accommodated by slip on northwest-trending, right-lateral strike-slip faults; this implies significant west-northwest elongation. Results of the investigation indicate that strike-slip faulting is the primary process accommodating crustal deformation along the Lake Mead fault system and that tilting in response to normal faulting is secondary.

  2. Vehicle yaw stability control using active limited-slip differential via model predictive control methods

    NASA Astrophysics Data System (ADS)

    Rubin, Daniel; Arogeti, Shai A.

    2015-09-01

    In this paper, the problem of vehicle yaw control using an active limited-slip differential (ALSD) applied on the rear axle is addressed. The controller objective is to minimise yaw-rate and body slip-angle errors, with respect to target values. A novel model predictive controller is designed, using a linear parameter-varying (LPV) vehicle model, which takes into account the ALSD dynamics and its constraints. The controller is simulated using a 10DOF Matlab/Simulink simulation model and a CarSim model. These simulations exemplify the controller yaw-rate and slip-angle tracking performances, under challenging manoeuvres and road conditions. The model predictive controller performances surpass those of a reference sliding mode controller, and can narrow the loss of performances due to the ALSD's inability to transfer torque regardless of driving conditions.

  3. Thermally activated phase slips in superfluid spin transport in magnetic wires

    NASA Astrophysics Data System (ADS)

    Kim, Se Kwon; Takei, So; Tserkovnyak, Yaroslav

    2016-01-01

    We theoretically study thermally activated phase slips in superfluid spin transport in easy-plane magnetic wires within the stochastic Landau-Lifshitz-Gilbert phenomenology, which runs parallel to the Langer-Ambegaokar-McCumber-Halperin theory for thermal resistances in superconducting wires. To that end, we start by obtaining the exact solutions for free-energy minima and saddle points. We provide an analytical expression for the phase-slip rate in the zero spin-current limit, which involves a detailed analysis of spin fluctuations at the extrema of the free energy. An experimental setup for a magnetoelectric circuit is proposed, in which thermal phase slips can be inferred by measuring nonlocal magnetoresistance.

  4. Analysis of Slip Activity and Deformation Modes in Tension and Tension-Creep Tests of Cast Mg-10Gd-3Y-0.5Zr (Wt Pct) at Elevated Temperatures Using In Situ SEM Experiments

    NASA Astrophysics Data System (ADS)

    Wang, Huan; Boehlert, Carl J.; Wang, Qudong; Yin, Dongdi; Ding, Wenjiang

    2016-05-01

    The tension and tension-creep deformation behavior at elevated temperatures of a cast Mg-10Gd-3Y-0.5Zr (wt pct, GW103) alloy was investigated using in situ scanning electron microscopy. The tests were performed at temperatures ranging from 473 K to 598 K (200 °C to 325 °C). The active slip systems were identified using an EBSD-based slip trace analysis methodology. The results showed that for all of the tests, basal slip was the most likely system to be activated, and non-basal slip was activated to some extent depending on the temperature. No twinning was observed. For the tension tests, non-basal slip consisted of ~35 pct of the deformation modes at low temperatures (473 K and 523 K (200 °C and 250 °C)), while non-basal slip accounted for 12 and 7 pct of the deformation modes at high temperatures (573 K and 598 K (300 °C and 325 °C)), respectively. For the tension-creep tests, non-basal slip accounted for 31 pct of the total slip systems at low temperatures, while this value decreased to 10 to 16 pct at high temperatures. For a given temperature, the relative activity for prismatic slip in the tension-creep tests was slightly greater than that for the tension tests, while the activity for pyramidal slip was lower. Slip-transfer in neighboring grains was observed for the low-temperature tests. Intergranular cracking was the main cracking mode, while some intragranular cracks were observed for the tension-creep tests at high temperature and low stress. Grain boundary ledges were prevalently observed for both the tension and tension-creep tests at high temperatures, which suggests that besides dislocation slip, grain boundary sliding also contributed to the deformation.

  5. Texture development and slip systems in bridgmanite and bridgmanite + ferropericlase aggregates

    NASA Astrophysics Data System (ADS)

    Miyagi, L.; Wenk, H.-R.

    2016-06-01

    Bridgmanite (Mg,Fe)SiO3 and ferropericlase (Mg,Fe)O are the most abundant phases in the lower mantle and localized regions of the D″ layer just above the core mantle boundary. Seismic anisotropy is observed near subduction zones at the top of the lower mantle and in the D″ region. One source of anisotropy is dislocation glide and associated texture (crystallographic preferred orientation) development. Thus, in order to interpret seismic anisotropy, it is important to understand texture development and slip system activities in bridgmanite and bridgmanite + ferropericlase aggregates. Here we report on in situ texture development in bridgmanite and bridgmanite + ferropericlase aggregates deformed in the diamond anvil cell up to 61 GPa. When bridgmanite is synthesized from enstatite, it exhibits a strong (4.2 m.r.d.) 001 transformation texture due to a structural relationship with the precursor enstatite phase. When bridgmanite + ferropericlase are synthesized from olivine or ringwoodite, bridgmanite exhibits a relatively weak 100 transformation texture (1.2 and 1.6 m.r.d., respectively). This is likely due to minimization of elastic strain energy as a result of Young's modulus anisotropy. In bridgmanite, 001 deformation textures are observed at pressures <55 GPa. The 001 texture is likely due to slip on (001) planes in the [100], [010] and < {110} rangle directions. Stress relaxation by laser annealing to 1500-1600 K does not result in a change in this texture type. However, at pressures >55 GPa a change in texture to a 100 maximum is observed, consistent with slip on the (100) plane. Ferropericlase, when deformed with bridgmanite, does not develop a coherent texture. This is likely due to strain heterogeneity within the softer ferropericlase grains. Thus, it is plausible that ferropericlase is not a significant source of anisotropy in the lower mantle.

  6. A complex systems analysis of stick-slip dynamics of a laboratory fault

    SciTech Connect

    Walker, David M.; Tordesillas, Antoinette; Small, Michael; Behringer, Robert P.; Tse, Chi K.

    2014-03-15

    We study the stick-slip behavior of a granular bed of photoelastic disks sheared by a rough slider pulled along the surface. Time series of a proxy for granular friction are examined using complex systems methods to characterize the observed stick-slip dynamics of this laboratory fault. Nonlinear surrogate time series methods show that the stick-slip behavior appears more complex than a periodic dynamics description. Phase space embedding methods show that the dynamics can be locally captured within a four to six dimensional subspace. These slider time series also provide an experimental test for recent complex network methods. Phase space networks, constructed by connecting nearby phase space points, proved useful in capturing the key features of the dynamics. In particular, network communities could be associated to slip events and the ranking of small network subgraphs exhibited a heretofore unreported ordering.

  7. Phase-locked servo system. [for synchronizing the rotation of slip ring assembly

    NASA Technical Reports Server (NTRS)

    Burdin, C. (Inventor)

    1974-01-01

    A phase lock servo system is described for synchronizing the rotation of a slip ring assembly with the rotation of an air bearing table so that a minimum of torque will be imparted through cables extending from the slip ring assembly to the air bearing table as such is rotated. The system includes two servo loops. The first servo loop includes a rate gyroscope carried on the air bearing table which generates a signal through a summing junction to be compared with a signal coming from a tachometer coupled to the slip ring assembly. The corrective signal is applied to a torque motor for rotating the slip ring assembly. The second servo loop includes a pair of photo detector cells which generate pulses responsive to the rotation of the air bearing table and slip ring assembly which are fed through a phase detector, and a variable gain amplifier to the summing junction circuit to provide a fine adjustment for rotating the slip ring assembly.

  8. Network and Dynamical System Analysis of a Granular Stick-Slip Experiment

    NASA Astrophysics Data System (ADS)

    Walker, David W.; Tordesillas, Antoinette; Small, M.; Behringer, R. P.

    2013-03-01

    We describe analysis of stick-slip behavior in a granular material under shear from a slider that is pulled across the granular surface. We extend previous statistical analysis, focusing on size distributions of failure events by applying nonlinear time series analysis, including surrogate data, and complex network methods. Local dimension measures suggest a robust evolution law of stick-slip dynamics needs at least 4 to 6 degrees of freedom. Surrogate methods indicate that individual stick-slip events may contain more complex nonlinear determinism periodic dynamics, although models with periodic dynamics are adequate for some cases. Within each stick-slip ``cycle'', we found evidence of nonlinear determinism but no long term memory across cycles. Representing the observed time series as a complex network, however, revealed that despite no evidence for long term dynamical correlations between distinct stick-slip events there is consistency in the structure of individual subnetworks associated with the onset of each slip event, possibly reflecting a single driving mechanism of failure, i.e. dynamics of force chains. When the data is representated as a complex network, it appears to present a new stratification of system dynamics with a previously unreported ranking, or genus, Support from ARO, including grant W911NF-1-11-0110

  9. Strike-slip accommodated core complexes in the Najd fault system, Arabian-Nubian shield

    NASA Astrophysics Data System (ADS)

    Meyer, S. E.; Passchier, C. W.; Abu-Alam, T. S.; Stuewe, K.

    2013-12-01

    Metamorphic core complexes are usually developed as extensional features during crustal thinning in a continental collision zone, such as the Basin and Range and the Aegean Terrane. The Najd fault system in Saudi Arabia is a 2000 km-long and 400 km-wide complex network of crustal-scale strike-slip shear zones in a Neoproterozoic collision zone. Locally, the anastomosing shear zones lead to exhumation of lower crustal segments and represent a new kinematic model for the development of core complexes. We report on two such dome structures: the Qazaz complex in Saudi Arabia and the Hafafit complex in Egypt. The 15-km-wide Qazaz complex is a triangular dome of gently dipping mylonitic foliations within the 140-km-long sinistral strike-slip Qazaz mylonite zone. The gneissic dome consists of high-grade rocks, surrounded by low-grade metasediments and metavolcanics. The main SE trending strike-slip Qazaz shear zone splits southwards into two branches around the gneiss dome: the western branch is continuous with the shallow dipping mylonites of the dome core, without overprinting, and curves by more than 90 degrees eastwards from a NS trending strike slip zone to an EW trending 40 degree south dipping detachment that bounds the gneiss dome to the south. The eastern SE trending sinistral strike slip shear zone branch is slightly younger and transects the central dome fabrics. The gneiss dome appears to have formed along a jog in the strike slip shear zone during 40 km of strike slip motion, which caused local exhumation of lower crustal rocks by 25 km along the detachment. The eastern shear zone branch formed late during exhumation, transacted the gneiss dome and offset the two parts by another 70 km. The Hafafit core complex in Egypt is of similar shape and size to the Qazaz structure, but forms the northern termination of a sinistral strike-slip zone that is at least 100 km in length. This zone may continue into Saudi Arabia as the Ajjaj shear zone for another 100 km. The

  10. Shallow Hydrothermal Flow in a Strike-Slip Fault System, Mt Isa, Australia: A Proterozoic Analog for Modern Geothermal Systems Along Strike-Slip Faults

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.; Ghisetti, F.; Begbie, M.

    2014-12-01

    Strong E-W shortening during the Isan Orogeny (1590-1500 Ma) led to crustal thickening and compressional inversion of former intracontinental rift basins. The resulting metamorphic/plutonic basement complex is disrupted by conjugate, mutually cross-cutting sets of brittle, late-orogenic strike-slip faults. Dextral strike-slip faults (separations < 25 km) strike NE-NNE, while conjugate sinistral faults strike SE-SSE, defining a wrench regime (σv = σ2) with horizontal maximum compression, σ1, trending c. 100°. The strike-slip faults are recessive except in dilational sites where upwelling hydrothermal fluids have silicified the cataclastic shear zones (CSZ) which protrude as blade-like ridges extending for kilometres across the semi-arid terrain. The mineralized fault segments include sinuous releasing bends where the fault trace is deflected <10° as well as more abrupt dilational stepovers with distributed extension fracturing linking en echelon fault segments. Other components of structural permeability include: (1) innumerable fault-parallel quartz-veins (cm to m thickness) within the CSZ; (2) irregular stringer veins; and (3) a regional set of predominantly extensional, subvertical planar quartz veins oriented 080-120° at moderate angles to the main faults. Broad contemporaneity is indicated by mutual cross-cutting relationships between all structural components. Measured strike separations along shear fractures are consistent with seismic slip increments which refreshed fracture permeability and promoted hydrothermal flow. Textures suggest the faults were exhumed from epithermal boiling environments (<1-2 km depth). Restoration of fault cohesive strength by hydrothermal cementation was critical in allowing continued vein formation by hydraulic extension fracturing. The distribution of hydrothermal quartz within the fault system provides a guide to structural localization of upflow zones in geothermal fields developed along strike-slip faults.

  11. Bond slip detection of concrete-encased composite structure using shear wave based active sensing approach

    NASA Astrophysics Data System (ADS)

    Zeng, Lei; Parvasi, Seyed Mohammad; Kong, Qingzhao; Huo, Linsheng; Lim, Ing; Li, Mo; Song, Gangbing

    2015-12-01

    Concrete-encased composite structure exhibits improved strength, ductility and fire resistance compared to traditional reinforced concrete, by incorporating the advantages of both steel and concrete materials. A major drawback of this type of structure is the bond slip introduced between steel and concrete, which directly reduces the load capacity of the structure. In this paper, an active sensing approach using shear waves to provide monitoring and early warning of the development of bond slip in the concrete-encased composite structure is proposed. A specimen of concrete-encased composite structure was investigated. In this active sensing approach, shear mode smart aggregates (SAs) embedded in the concrete act as actuators and generate desired shear stress waves. Distributed piezoceramic transducers installed in the cavities of steel plates act as sensors and detect the wave response from shear mode SAs. Bond slip acts as a form of stress relief and attenuates the wave propagation energy. Experimental results from the time domain analysis clearly indicate that the amplitudes of received signal by lead zirconate titanate sensors decreased when bond slip occurred. In addition, a wavelet packet-based analysis was developed to compute the received signal energy values, which can be used to determine the initiation and development of bond slip in concrete-encased composite structure. In order to establish the validity of the proposed method, a 3D finite element analysis of the concrete-steel bond model is further performed with the aid of the commercial finite element package, Abaqus, and the numerical results are compared with the results obtained in experimental study.

  12. Determining the long-term slip rate of the Pernicana Fault System, Mt. Etna, to improve earthquake forecast modelling

    NASA Astrophysics Data System (ADS)

    D'Amato, Davide; Pace, Bruno; Di Nicola, Luigia; Stuart, Finlay M.; Barfod, Dan; Branca, Stefano; Azzaro, Raffaele; Visini, Francesco

    2013-04-01

    The Pernicana fault system (PFS) is a complex active tectonic systems located in the NE sector of Mt. Etna. It represents the northern boundary of the sliding side of the volcano and plays an important role in the dynamics of the eastern flank. Several historic and recent earthquakes have occurred close to this structure with coseismic surface faulting and damage (e.g. 02/04/2010 earthquake, Mw = 4.2). The PFS is transtensive, characterised by complex of en echelon segments with a N 110° overall direction. The dip-slip component decreases to the East accompanied with a decreasing of seismic activity. The eastern-most segment is characterised by left aseismic creeping strike-slip motion. The aim of this work is to constrain to constrain the long-term history of the PFS using 40Ar/39Ar and cosmogenic 3He ages of lava flows that are cut by the PFS in order to better understand the fault behaviour and improve the prediction of earthquake occurrence. We will present the first 3D shape of the PFS based on a network of detailed topographic profiles, to better constrain the variability of the fault scarp along strike and so the kinematics of the structure. In situ cosmogenic 3He exposure ages of two faulted lava flows from the central sector of PFS are used to determine the slip rate. Flow ages (1157 ± 230 yr and 1088 ± 96 yr) are combined with fault scarp heights to calculate an average vertical slip rate of about 11 mm/year over the last 1,000 years for the central section of the PFS. This rate is close to the rate determined from historical and geodetic data (displacement of antropic manufact and geodetic levelling), covering the last 20 years. It suggests that the slip-rates have not changed significantly in the last 1,000 years. The new fault geometry and slip rate data have been used to realise a kinematic and strain model of the PFS, in order to distinguish the vertical and the horizontal slip rate components and to model the tectonic and volcanic strain fields

  13. Influence of slip system hardening assumptions on modeling stress dependence of work hardening

    NASA Astrophysics Data System (ADS)

    Miller, Matthew; Dawson, Paul

    1997-11-01

    Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on the macroscopic flow stress can be quantified in a polycrystal by the average Taylor factor M¯. Sources of resistance to dislocation motion such as interaction with dislocation structures, precipitates, and grain boundaries, contribute to the elevation of the critically resolved shear strength τcrss. In continuum slip polycrystal formulations, material hardening phenomena are reflected in the slip system hardness equations. Depending on the model, the hardening equations and the mean field assumption can both affect geometric hardening through texture evolution. In this paper, we examine continuum slip models and focus on how the slip system hardening model and the mean field assumption affect the stress-strain response. Texture results are also presented within the context of how the texture affects geometric hardening. We explore the effect of employing slip system hardnesses averaged over different size scales. We first compare a polycrystal simulation employing a single hardness per crystal to one using a latent hardening formulation producing distinct slip system hardnesses. We find little difference between the amplitude of the single hardness and a crystal-average of the latent hardening values. The geometric hardening is different due to the differences in the textures predicted by each model. We also find that due to the high degree of symmetry in an fcc crystal, macroscopic stress-strain predictions using simulations employing crystal- and aggregateaveraged hardnesses are nearly identical. We find this to be true for several different mean field assumptions. An aggregate-averaged hardness may be preferred in light of the difficulty

  14. Slip Rates of Main Active Fault Zones Through Turkey Inferred From GPS Observations

    NASA Astrophysics Data System (ADS)

    Ozener, H.; Aktug, B.; Dogru, A.; Tasci, L.; Acar, M.; Emre, O.; Yilmaz, O.; Turgut, B.; Halicioglu, K.; Sabuncu, A.; Bal, O.; Eraslan, A.

    2015-12-01

    Active Fault Map of Turkey was revised and published by General Directorate of Mineral Research and Exploration in 2012. This map reveals that there are about 500 faults can generate earthquakes.In order to understand the earthquake potential of these faults, it is needed to determine the slip rates. Although many regional and local studies were performed in the past, the slip rates of the active faults in Turkey have not been determined. In this study, the block modelling, which is the most common method to produce slip rates, will be done. GPS velocities required for block modeling is being compiled from the published studies and the raw data provided then velocity field is combined. To form a homogeneous velocity field, different stochastic models will be used and the optimal velocity field will be achieved. In literature, GPS site velocities, which are computed for different purposes and published, are combined globally and this combined velocity field are used in the analysis of strain accumulation. It is also aimed to develop optimal stochastic models to combine the velocity data. Real time, survey mode and published GPS observations is being combined in this study. We also perform new GPS observations. Furthermore, micro blocks and main fault zones from Active Fault Map Turkey will be determined and homogeneous velocity field will be used to infer slip rates of these active faults. Here, we present the result of first year of the study. This study is being supported by THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY (TUBITAK)-CAYDAG with grant no. 113Y430.

  15. Active faulting induced by the slip partitioning in the Lesser Antilles arc

    NASA Astrophysics Data System (ADS)

    Leclerc, Frédérique; Feuillet, Nathalie

    2010-05-01

    AGUADOMAR marine cruise data acquired 11 years ago allowed us to identified and map two main sets of active faults within the Lesser Antilles arc (Feuillet et al., 2002; 2004). The faults belonging to the first set, such as Morne-Piton in Guadeloupe, bound up to 100km-long and 50km-wide arc-perpendicular graben or half graben that disrupt the fore-arc reef platforms. The faults of the second set form right-stepping en echelon arrays, accommodating left-lateral slip along the inner, volcanic islands. The two fault systems form a sinistral horsetail east of the tip of the left-lateral Puerto Rico fault zone that takes up the trench-parallel component of convergence between the North-American and Caribbean plates west of the Anegada passage. In other words, they together accommodate large-scale slip partitioning along the northeastern arc, consistent with recent GPS measurements (Lopez et al., 2006). These intraplate faults are responsible for a part of the shallow seismicity in the arc and have produce damaging historical earthquakes. Two magnitude 6.3 events occurred in the last 25 years along the inner en echelon faults, the last one on November 21 2004 in Les Saintes in the Guadeloupe archipelago. To better constrain the seismic hazard related to the inner arc faults and image the ruptures and effects on the seafloor of Les Saintes 2004 earthquake, we acquired new marine data between 23 February and 25 March 2009 aboard the French R/V le Suroît during the GWADASEIS cruise. We present here the data (high-resolution 72 channel and very high-resolution chirp 3.5 khz seismic reflection profiles, EM300 multibeam bathymetry, Küllenberg coring and SAR imagery) and the first results. We identified, mapped and characterized in detail several normal to oblique fault systems between Martinique and Saba. They offset the seafloor by several hundred meters and crosscut all active volcanoes, among them Nevis Peak, Soufriere Hills, Soufriere de Guadeloupe and Montagne Pel

  16. Slip instability development and earthquake nucleation as a dynamical system's fixed-point attraction

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.

    2014-12-01

    A fault's transition from slow creep to the propagation of an earthquake-generating dynamic rupture is thought to start as a quasi-static slip instability. Here we examine how such an instability develops on a sliding interface whose strength is governed by a slip rate- and state-dependent friction, where the state variable evolves according to the aging law. We find that the development occurs as the attraction of a dynamical system to a fixed point. The fixed points are such that the state of slip and the rate at which velocity diverges (and its spatial distribution) are known. The fixed points are independent of the manner of external forcing and the values of slip rate and state before the onset of instability. For a fault under uniform normal stress and frictional properties, the sole parameter that determines the fixed point (to within a translational invariance) is the ratio of the frictional parameters, a/b (where, for steady-state rate weakening, 0slip instability may develop in a chaotic fashion. The fixed-point solutions, as well as the critical thresholds concerning their stability, depend on the configuration of slip (e.g., in/anti-plane or mixed-mode slip) and the elastic environment in which the interface is embedded (e.g., a slip surface between elastic half-spaces or one lying below and parallel to a free surface); solving for a fixed point reduces to the solution of an equivalent problem of an equilibrium slip-weakening fracture; and fixed-point stability is determined by linear stability analysis. Solutions of

  17. Preventing Slips and Falls through Leisure-Time Physical Activity: Findings from a Study of Limited-Service Restaurants

    PubMed Central

    Caban-Martinez, Alberto J.; Courtney, Theodore K.; Chang, Wen-Ruey; Lombardi, David A.; Huang, Yueng-Hsiang; Brennan, Melanye J.; Perry, Melissa J.; Katz, Jeffrey N.; Verma, Santosh K.

    2014-01-01

    Background/Objective Physical activity has been shown to be beneficial at improving health in some medical conditions and in preventing injury. Epidemiologic studies suggest that physical activity is one factor associated with a decreased risk for slips and falls in the older (≥65 years) adult population. While the risk of slips and falls is generally lower in younger than in older adults; little is known of the relative contribution of physical activity in preventing slips and falls in younger adults. We examined whether engagement in leisure-time physical activity (LTPA) was protective of slips and falls among a younger/middle-aged (≤50 years old) working population. Methods 475 workers from 36 limited-service restaurants in six states in the U.S. were recruited to participate in a prospective cohort study of workplace slipping. Information on LTPA was collected at the time of enrollment. Participants reported their slip experience and work hours weekly for up to 12 weeks. We investigated the association between the rate of slipping and the rate of major slipping (i.e., slips that resulted in a fall and/or injury) and LTPA for workers 50 years of age and younger (n = 433, range 18–50 years old) using a multivariable negative binomial generalized estimating equation model. Results The rate of major slips among workers who engaged in moderate (Adjusted Rate Ratio (RR)  = 0.65; 95% Confidence Interval (CI)  =  [0.18–2.44]) and vigorous (RR = 0.64; 95%CI  =  [0.18–2.26]) LTPA, while non-significant, were approximately one-third lower than the rate of major slips among less active workers. Conclusion While not statistically significant, the results suggest a potential association between engagement in moderate and vigorous LTPA and the rate of major slips in younger adults. Additional studies that examine the role of occupational and non-occupational physical activity on the risk of slips, trips and falls among younger and middle aged

  18. Plasticity of hexagonal systems: Split slip modes and inverse Peierls relation in α-Ti

    NASA Astrophysics Data System (ADS)

    Kwaśniak, Piotr; Śpiewak, Piotr; Garbacz, Halina; Kurzydłowski, Krzysztof J.

    2014-04-01

    The plasticity of hexagonal titanium is reexamined based on the split slip modes phenomenon, revealing the existence of subslip modes in prismatic and pyramidal hcp slip systems. The energetics of dislocation emission and motions were described using all-dimension relaxed atomic models of crystal slip, calculated with density functional theory. The proposed computational methodology is based on the generalized stacking fault energy concept and respects all elastic effects arising within dislocation nucleation. As a result, improved accuracy has been obtained with regard to ductility prediction and a breach has been discovered in the fundamental Peierls-Nabarro rule. This approach is essential for the Rice and Peierls-Nabarro models and can be used as an effective tool for ductility predictions when designing new hexagonal alloys.

  19. Influence of tire dynamics on slip ratio estimation of independent driving wheel system

    NASA Astrophysics Data System (ADS)

    Li, Jianqiu; Song, Ziyou; Wei, Yintao; Ouyang, Minggao

    2014-11-01

    The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor(I-PMSM) and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn't equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface(a slippery road) is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies(NFs) of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation.

  20. GPS-derived slip rates of active faults in eastern Venezuela, along the southeastern Caribbean PBZ

    NASA Astrophysics Data System (ADS)

    Audemard, F. A.; Beck, C.; Jouanne, F.; Reinoza, C. E.; Fegag

    2013-05-01

    For over 20 years, GPS campaign measurements have been performed in eastern Venezuela, as well as in other areas of the country, by different scientific groups and in the frame of different either national or international efforts and/or projects, essentially aiming at the estimation of the rate of motion along the major Quaternary faults (i.e., Boconó, San Sebastián and El Pilar faults) composing the plate boundary zone (PBZ) between the Caribbean and South America, along onshore northern and western Venezuela. The slip rates and sense of slip of those major faults derived from the comparison of several GPS campaigns carried out through the years have confirmed the slip data (fault kinematics) previously derived from geologic data, through comprehensive neotectonic and paleoseismic studies mainly made by the FUNVISIS' Earth Sciences Dpt. staff. In a rough way, we could conclude that those faults are dextrally moving at a rate in the order of 10-12 mm/a. More recently, it has been shown that the El Pilar fault has a locking depth close to 10 km deep and that about half of the PBZ dextral motion is accommodated as creep, reducing the seismic hazard for northeastern Venezuela almost by half. On the contrary, in the near past, very little attention has been paid to the secondary active faulting in eastern Venezuela. In that sense, FUNVISIS, in collaboration with the Université de Savoie, started the monitoring of these secondary features by installing 36 brass benchmarks on bedrock in that region in 2003, which have been occupied 3 times, in late 2003 and 2005 and in early 2013. The comparison between the 2003 and 2005 occupations shows promising results, such as: a) The Charagato fault on Cubagua island is left-lateral with a slip rate of about 2 mm/a; b) slip vectors across the El Pilar fault tend to head to the ESE, suggesting that the tectonic regime is compressive transcurrent to transcurrent compressional (transpressional); c) The NW-SE-trending San Francisco

  1. Active interplay between strike-slip and extensional structures in a Back-Arc environment, Bay of Plenty, New Zealand

    NASA Astrophysics Data System (ADS)

    Barnes, P. M.; Lamarche, G.; Bull, J. M.

    2003-12-01

    Active continental back-arc tectonics associated with the oblique Hikurangi subduction zone, North Island, New Zealand, is characterized by (1) extensional deformation distributed across a 40-50 km-wide zone, but presently concentrated in the east within the 20 km-wide, NE-striking Taupo Fault Belt (TFB) and Whakatane Graben (WG); (2) c. 12mm/yr extension rate at the Bay of Plenty coast; (3) 1-3 mm/yr subsidence in the WG; and (4) a seismogenic zone estimated to be 6-9 km thick. A component of the oblique convergence within the plate boundary is partitioned to the east onto the adjacent North Island Dextral Fault Belt (NIDFB), a large NNE-trending strike-slip fault system traversing the entire North Island. At the Bay of Plenty coast, the NIDFB strikes north, with an estimated strike-slip rate of at least 1 mm/yr. Both normal and strike-slip fault systems extend beneath the continental shelf in the Bay of Plenty, and because of differences in their strike, they converge and interact. Detailed mapping of faults using marine seismic reflection profiles and multibeam bathymetric data reveals the structure of the WG. Tilted basement blocks are associated with large west-dipping faults, numerous antithetic secondary faults, and domino-style fault arrays. Eastward migration of the principal extension zone during the last c. 1 Myrs has resulted in the encroachment and oblique overprinting of the NIDFB by the WG. The structure and geometry of the White Island Fault (WIF), currently the principal fault along the eastern margin of the graben, results from interaction and linkage of the two fault systems. The displacement profile of this fault reveals relatively young NE-striking sections that obliquely link more northerly-striking, inherited components of the NIDFB. Understanding of the fault structure and evolution may have implications for the interpretation of earthquake potential close to urban centres.

  2. Block-like motion of Tibetan Plateau: Evidences from active faults , GPS velocities and recent earthquake slips

    NASA Astrophysics Data System (ADS)

    Xu, X.; Cheng, J.

    2012-12-01

    Collision of India with Eurasia during the past ~ 55 million years has created the high Tibetan Plateau with a flat interior at an average altitude of ~ 5000 m (Matte et al., 1996; Tapponnier et al., 1986, 2001). Two alternative end-member models of how the Tibetan Plateau formed have been proposed: (1) continuous thickening and widespread viscous channel flow of the crust and mantle of the entire plateau (e. g. Bai et al., 2011; Beaumont et al., 2001; Bendick and Flesch, 2007; Clark and Royden, 2000; Houseman and England, 1996; Royden et al., 1997; Shen F. et al., 2001; Zhang et al., 2004; Bai et al., 2010), and (2) time-dependent, localized shear between coherent lithospheric blocks (e. g. Avouac and Tapponnier, 1993; Peltzer and Saucier, 1996; Replumaz and Tapponnier, 2003; Ryerson et al., 2006; Tapponnier et al., 2001; Thatcher, 2007). A new 3-D mechanical model, in which the underthrust India and Tibet are strongly coupled, seems to explain spatial variation in faulting style, and to be inconsistent with channel-flow model for the southern Tibet (Copley et al., 2011). This 3-D model has placed important new constraints on mechanical behavior of the Tibetan lithosphere in its most extreme environment and forced a critical evaluation of the Tibetan channel flow models (Freymueller, 2011), but does not match details of the GPS velocity field, and underestimates the EW extension rate across the southern Tibet. More important is that the model approximates Tibet as a continuous medium, and cannot include localized slip on the mega-strike-slip fault systems, and thus cannot further discuss relationship among the eastward block-like motion, mega-strike-slip faults, normal faults and thrust faults in and around the Tibetan Plateau. It has been recognized for many years that GPS data are likely to be ultimately decisive in distinguishing between block-like and continuous models, at least for describing present-day deformation. Nonetheless, both block-like models and

  3. Free energy of dislocations in a multi-slip geometry

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, M. G. D.

    2016-03-01

    The collective dynamics of dislocations is the underlying mechanism of plastic deformation in metallic crystals. Dislocation motion in metals generally occurs on multiple slip systems. The simultaneous activation of different slip systems plays a crucial role in crystal plasticity models. In this contribution, we study the energetic interactions between dislocations on different slip systems by deriving the free energy in a multi-slip geometry. In this, we restrict ourselves to straight and parallel edge dislocations. The obtained free energy has a long-range mean-field contribution, a statistical contribution and a many-body contribution. The many-body contribution is a local function of the total dislocation density on each slip system, and can therefore not be written in terms of the net dislocation density only. Moreover, this function is a strongly non-linear and non-convex function of the density on different slip systems, and hence the coupling between slip systems is of great importance.

  4. Strike-slip fault geometry in Turkey and its influence on earthquake activity

    NASA Technical Reports Server (NTRS)

    Barka, A. A.; Kadinsky-Cade, K.

    1988-01-01

    The geometry of Turkish strike-slip faults is reviewed, showing that fault geometry plays an important role in controlling the location of large earthquake rupture segments along the fault zones. It is found that large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 degrees. It is suggested that certain geometric patterns are responsible for strain accumulation along portions of the fault zone. It is shown that fault geometry plays a role in the characteristics of earthquake behavior and that aftershocks and swarm activity are often associated with releasing areas.

  5. Contact line motion in confined liquid-gas systems: Slip versus phase transition.

    PubMed

    Xu, Xinpeng; Qian, Tiezheng

    2010-11-28

    In two-phase flows, the interface intervening between the two fluid phases intersects the solid wall at the contact line. A classical problem in continuum fluid mechanics is the incompatibility between the moving contact line and the no-slip boundary condition, as the latter leads to a nonintegrable stress singularity. Recently, various diffuse-interface models have been proposed to explain the contact line motion using mechanisms missing from the sharp-interface treatments in fluid mechanics. In one-component two-phase (liquid-gas) systems, the contact line can move through the mass transport across the interface while in two-component (binary) fluids, the contact line can move through diffusive transport across the interface. While these mechanisms alone suffice to remove the stress singularity, the role of fluid slip at solid surface needs to be taken into account as well. In this paper, we apply the diffuse-interface modeling to the study of contact line motion in one-component liquid-gas systems, with the fluid slip fully taken into account. The dynamic van der Waals theory has been presented for one-component fluids, capable of describing the two-phase hydrodynamics involving the liquid-gas transition [A. Onuki, Phys. Rev. E 75, 036304 (2007)]. This theory assumes the local equilibrium condition at the solid surface for density and also the no-slip boundary condition for velocity. We use its hydrodynamic equations to describe the continuum hydrodynamics in the bulk region and derive the more general boundary conditions by introducing additional dissipative processes at the fluid-solid interface. The positive definiteness of entropy production rate is the guiding principle of our derivation. Numerical simulations based on a finite-difference algorithm have been carried out to investigate the dynamic effects of the newly derived boundary conditions, showing that the contact line can move through both phase transition and slip, with their relative contributions

  6. Contact line motion in confined liquid-gas systems: Slip versus phase transition

    NASA Astrophysics Data System (ADS)

    Xu, Xinpeng; Qian, Tiezheng

    2010-11-01

    In two-phase flows, the interface intervening between the two fluid phases intersects the solid wall at the contact line. A classical problem in continuum fluid mechanics is the incompatibility between the moving contact line and the no-slip boundary condition, as the latter leads to a nonintegrable stress singularity. Recently, various diffuse-interface models have been proposed to explain the contact line motion using mechanisms missing from the sharp-interface treatments in fluid mechanics. In one-component two-phase (liquid-gas) systems, the contact line can move through the mass transport across the interface while in two-component (binary) fluids, the contact line can move through diffusive transport across the interface. While these mechanisms alone suffice to remove the stress singularity, the role of fluid slip at solid surface needs to be taken into account as well. In this paper, we apply the diffuse-interface modeling to the study of contact line motion in one-component liquid-gas systems, with the fluid slip fully taken into account. The dynamic van der Waals theory has been presented for one-component fluids, capable of describing the two-phase hydrodynamics involving the liquid-gas transition [A. Onuki, Phys. Rev. E 75, 036304 (2007)]. This theory assumes the local equilibrium condition at the solid surface for density and also the no-slip boundary condition for velocity. We use its hydrodynamic equations to describe the continuum hydrodynamics in the bulk region and derive the more general boundary conditions by introducing additional dissipative processes at the fluid-solid interface. The positive definiteness of entropy production rate is the guiding principle of our derivation. Numerical simulations based on a finite-difference algorithm have been carried out to investigate the dynamic effects of the newly derived boundary conditions, showing that the contact line can move through both phase transition and slip, with their relative contributions

  7. Slip history of the 1944 Bolu-Gerede earthquake rupture along the North Anatolian fault system: Implications for recurrence behavior of multisegment earthquakes

    NASA Astrophysics Data System (ADS)

    Kondo, Hisao; Ã-Zaksoy, Volkan; YıLdirim, Cengiz

    2010-04-01

    Recent research shows that active fault systems produce multisegment earthquakes; however, we have yet to understand the faulting behavior of various spatial patterns of segments. We conducted a three-dimensional trenching survey to reconstruct the detailed slip history of a fault segment that ruptured as one of the multisegment ruptures along the North Anatolian fault system. The trench site, on the Gerede segment, recorded a maximum right-lateral slip of up to 6 m that was associated with the 1944 Bolu-Gerede earthquake (M 7.4). Fault exposures show evidence of four paleoearthquakes. Radiocarbon dates, a refined probability density distribution, and correlation with historical earthquakes place the mean repeat time at ˜330 years. Four discrete paleoslips yield a slip per event of 5.0 ± 0.8 m with a coefficient of variation of 0.2. Our research suggests that multisegment earthquakes exhibit various spatial patterns, regardless of recurrence with quasiperiodicity and characteristic slip. Coincidentally, the fault geometry exhibits extremely linear traces, suggesting simple stress accumulation and release through earthquake cycles. Furthermore, the 1944 event did not occur in a single segment, and the Gerede segment probably ruptured within a slip-pulse-like rupture during a multisegment earthquake. A comparable geological slip rate of ˜17 mm a-1 based on a GPS-based strain rate supports the persistence of macroscopic asperity through recent geological time. Therefore we conclude that a segment with simple fault geometry along a strike-slip fault system plays an important role in forecasting the timing of future multisegment earthquakes, but the spatial extent of such earthquakes needs to be explored further.

  8. Architectural evolution of the Nojima fault and identification of the activated slip layer by Kobe earthquake

    NASA Astrophysics Data System (ADS)

    Tanaka, Hidemi; Omura, Kentaro; Matsuda, Tatsuo; Ikeda, Ryuji; Kobayashi, Kenta; Murakami, Masaki; Shimada, Koji

    2007-07-01

    Evolutionary history of Nojima Fault zone is clarified by comprehensive examinations of petrological, geophysical, and geochemical characterizations on a fault zone in deep-drilled core penetrating the Nojima Fault. On the basis of the results, we reconstruct a whole depth profile of the architecture of the Nojima Fault and identify the primal slip layer activated by 1995 Kobe earthquake. The deepest part (8- to 12-km depth) of the fault zone is composed of thin slip layers of pseudotachylite (5 to 10 mm thick each, 10 cm in total). Middle depth (4- to 8-km depth) of the fault zone is composed of fault core (6 to 10 m thick), surrounded by thick (100 m thick) damage zone, characterized by zeolite precipitation. The shallow part of the fault zone (1- to 4-km depth) is composed of distributed narrow shear zones, which are characterized by combination of thin (0.5 cm thick each, 10 cm in total) ultracataclasite layers at the core of shear zones, surrounded by thicker (1 to 3 m thick) damage zones associated with carbonate precipitation. An extremely thin ultracataclasite layer (7 mm thick), activated by the 1995 Kobe earthquake, is clearly identified from numerous past slip layers, overprinting one of the shear zones, as evidenced by conspicuous geological and geophysical anomalies. The Nojima Fault zone was 10 to 100 times thicker at middle depth than that of shallower and deeper depths. The thickening would be explained as a combination of physical and chemical effects as follows. (1) Thickening of "fault core" at middle depth would be attributed to normal stress dependence on thickness of the shear zone and (2) an extreme thickening of "damage zone" in middle depth of the crust would result from the weakening of the fault zone due to super hydrostatic fluid pressure at middle depths. The high fluid pressure would result from faster sealing with low-temperature carbonate at the shallower fault zone.

  9. Precursory Seismic Activity Surrounding the High-Slip Patches of the 2011 Mw9.0 Tohoku-Oki Earthquake

    NASA Astrophysics Data System (ADS)

    Sato, T.; Hiratsuka, S.; Mori, J. J.

    2013-12-01

    The 11 March 2011 Tohoku-Oki earthquake (Mw9.0) occurred on the megathrust along the western margin of the Pacific Ocean where the Pacific plate is being subducted beneath the island of Honshu, Japan. The slip near the Japan Trench was estimated to be enormous; it averaged about 40 m over the upper 100 km of the megathrust and peaked at 60-80 m close to the trench (Lay et al., 2011; Ozawa et al., 2012; Iinuma et al., 2012). Nearly a thousand years are required to accumulate such a large slip for the convergence rate of 8-9 cm/yr along this plate boundary zone. Two days before the Tohoku-Oki earthquake, foreshock activity (largest event M7.3) occurred north of the main-shock epicenter. The epicentral area of the foreshock activity is similar to a M7.0 earthquake in 1981 (Shao et al., 2011). The question arises, why did the 1981 event not trigger a great earthquake? A time difference of 30 years is negligible in comparison with the long time required for the slip deficit of more than 40 m. In order to address this question, we investigated the seismic activity prior to the Tohoku-Oki earthquake using the earthquake catalogue compiled by the Japan Meteorological Agency (JMA) since 1923. For the purpose of the present study, we independently determined the slip distribution of the Tohoku-Oki earthquake, using the coseismic displacements derived from the GEONET GPS stations on land (Ozawa et al., 2011) and those from the offshore GPS stations and ocean-bottom water pressure gauges (Sato et al., 2011; Iinuma et al., 2012). The slip distribution is characterized by two high-slip ( 20m) patches separated by a zone of relatively low slip. The peak of the northern high-slip patch is located near the trench while the peak of the southern high-slip patches are situated about 40 km southeast of the main-shock epicenter, about 70 km away from the trench. Combined with the analyses of main-shock rupture process by Ide et al. (2011) and Shao et al. (2011), it is estimated that the

  10. A new slip stacking RF system for a twofold power upgrade of Fermilab's Accelerator Complex

    SciTech Connect

    Madrak, Robyn

    2014-09-11

    Fermilab@?s Accelerator Complex has been recently upgraded, in order to increase the 120GeV proton beam power on target from about 400kW to over 700kW for NO@nA and other future intensity frontier experiments. One of the key ingredients of the upgrade is the offloading of some Main Injector synchrotron operations - beam injection and RF manipulation called ''slip stacking'' - to the 8GeV Recycler Ring, which had until recently been used only for low-intensity antiproton storage and cooling. This required construction of two new 53MHz RF systems for the slip-stacking manipulations. The cavities operate simultaneously at V_p_e_a_k@?150kV, but at slightly different frequencies (@Df=1260Hz). Their installation was completed in September 2013. This paper describes the novel solutions used in the design of the new cavities, their tuning system, and the associated high power RF system. First results showing effective operation of the RF system, beam capture and successful slip-stacking in the Recycler Ring are presented.

  11. Spatiotemporal stick-slip phenomena in a coupled continuum-granular system

    NASA Astrophysics Data System (ADS)

    Ecke, Robert

    In sheared granular media, stick-slip behavior is ubiquitous, especially at very small shear rates and weak drive coupling. The resulting slips are characteristic of natural phenomena such as earthquakes and well as being a delicate probe of the collective dynamics of the granular system. In that spirit, we developed a laboratory experiment consisting of sheared elastic plates separated by a narrow gap filled with quasi-two-dimensional granular material (bi-dispersed nylon rods) . We directly determine the spatial and temporal distributions of strain displacements of the elastic continuum over 200 spatial points located adjacent to the gap. Slip events can be divided into large system-spanning events and spatially distributed smaller events. The small events have a probability distribution of event moment consistent with an M - 3 / 2 power law scaling and a Poisson distributed recurrence time distribution. Large events have a broad, log-normal moment distribution and a mean repetition time. As the applied normal force increases, there are fractionally more (less) large (small) events, and the large-event moment distribution broadens. The magnitude of the slip motion of the plates is well correlated with the root-mean-square displacements of the granular matter. Our results are consistent with mean field descriptions of statistical models of earthquakes and avalanches. We further explore the high-speed dynamics of system events and also discuss the effective granular friction of the sheared layer. We find that large events result from stored elastic energy in the plates in this coupled granular-continuum system.

  12. Fault Slip Rate of the Kazerun Fault System (KFS), Iran, Investigated Using Finite Element Modeling

    NASA Astrophysics Data System (ADS)

    Shoorcheh, Bijan; Motagh, Mahdi; Baes, Marzieh; Bahroudi, Abbas

    2015-10-01

    A 3D non-homogenous finite element model (FEM) is developed to investigate the spatial variations of interseismic deformation for the Kazerun Fault System (KFS) in the Zagros Mountains of Iran. The model includes 19 fault segments that were extracted from geological maps and previous studies, and the average slips in the dip and strike directions on these segments were computed. The contemporary surface deformation is simulated using a free horizontal detachment surface. The dip angles of the faults in the model are varied at 90°, 70°, 50° and 30° to simulate different 3D representations of the fault systems. Tectonic loading at the boundaries of the region is applied using predicted GPS velocity vectors to the north (southern part of the Central Iran Block) and south (southern region of the Zagros mountain belt), which were obtained by solving inverse and forward problems. Where possible, the fault slip rates that are obtained using our non-homogeneous finite element model are validated using the long-term geologic and instantaneous GPS slip rates. The model is then used to estimate the dip- and strike-slip rates of the fault segments of the KFS for which no a priori information was available. We derive an upper bound of 1 mm/year for the average dip-slip rate in the region, which is consistent with estimates from geomorphologic observations. The modeling results show that in addition to the 4 main faults (Dena, Kazerun, Kareh Bas and Main Recent), other faults, such as the Zagros Front, Main Front, High Zagros and Mishan faults, accommodate up to 2.5 mm/year of the differential movement between the North and Central Zagros. We also investigated the contrast in rigidity between the southern and northern areas of the Zagros mountain belt and found that a rigidity contrast of 2 best explains the GPS data of contemporary surface deformation. Neglecting to account for the rigidity contrast in the model can lead to biased estimates of the fault slip rate of up to

  13. Glide of dislocations in <1 1 1>{3 2 1} slip system: an atomistic study

    NASA Astrophysics Data System (ADS)

    Terentyev, D.; Bakaev, A.; Van Neck, D.; Zhurkin, E. E.

    2016-01-01

    Atomistic calculations are performed to investigate plastic slip in the <1 1 1>{3 2 1} system in body-centred cubic iron. Several modern interatomic potentials, developed over the last decade, are applied to compute the stacking fault γ-line energy in the {3 2 1} plane and the results are compared with the ab initio prediction. The applied potentials have shown strong deviations, but several potentials acquired good qualitative agreement with the ab initio data. Depending on the applied potential, the lowest value of the Peierls stress for the edge dislocation (ED) is 50 MPa (Ackland and Bacon from 1997) and the highest is 550 MPa (Dudarev and Derlet from 2005), while for the screw dislocation it is much higher, in the range 1-2 GPa. At finite temperature, however, the flow stress of the ED is found to decrease exponentially reaching a negligible value at about 200 K, irrespective of the applied potential. On the basis of the data obtained using Ackland-Mendelev potential from 2004, we conclude that the slip resistance of the <1 1 1>{3 2 1} system is in between the resistance of the <1 1 1>{1 1 0} and <1 1 1>{1 1 2} slip systems.

  14. Pilot-symbols-aided cycle slip mitigation for DP-16QAM optical communication systems.

    PubMed

    Cheng, Haiquan; Li, Yan; Zhang, Fangzheng; Wu, Jian; Lu, Jianxin; Zhang, Guoyi; Xu, Jian; Lin, Jintong

    2013-09-23

    A pilot-symbols-aided phase unwrapping (PAPU), which utilizes the time-division multiplexed pilot symbols that are transmitted with data, is proposed to do cycle slip detection and correction with the carrier phase estimation (CPE). Numerical simulations for 10 Gbaud dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM) systems show that the block averaging quadrature phase-shift keying (QPSK) partitioning with PAPU greatly eliminates the performance degradation caused by cycle slips, maintains a low CS probability with less influence of filter length, and achieves a bit-error-rate (BER) performance below soft-decision forward error correction (FEC) limit 2 × 10⁻² at 15 dB optical signal-to-noise ratio with only 1.56% overhead and 6 MHz combined laser linewidth. PMID:24104108

  15. Modeling Strike-Slip-Driven Stream Capture in Detachment- and Transport-Limited Fluvial Systems

    NASA Astrophysics Data System (ADS)

    Harbert, S.; Duvall, A. R.; Tucker, G. E.

    2014-12-01

    Rivers, especially those in mountainous settings, are known to respond to tectonic and climatic drivers through both gradual and abrupt changes in slope, hydraulic geometry, and planform. Modification of drainage network topology by stream capture, in which drainage area, and therefore water and sediment, is diverted suddenly from one catchment into another, represents the rapid end of the fluvial response spectrum. Such sudden drainage rearrangement affects the river's potential for incision and sediment transport, and thus has implications for the development of topography and for depositional histories in sedimentary basins. Despite recognition of the importance of this process in landscape evolution, the factors controlling the occurrence of stream capture are not well understood. Here we investigate the process of stream capture using strike-slip faults as a natural experiment. Lateral fault motion drives stream capture when offset is enough to juxtapose adjacent fault-perpendicular streams. In the simplest scenario, the capture events should occur regularly in space and time whenever two streams are juxtaposed, the frequency of capture depending only on drainage spacing and fault slip rate. However, in real-world settings such as the San Andreas Fault Zone of California and the Marlborough Fault System of New Zealand, such regularity is not always observed. We use the Channel-Hillslope Integrated Landscape Development Model (CHILD) to investigate the mechanisms and frequency of stream capture in a strike-slip setting. Models are designed to address the connection between the size (i.e. drainage area) of juxtaposed rivers and the likelihood that capture will occur between them. We also explore the role of sediment load in the capture process by modeling both detachment-limited and transport-limited systems. Comparison of these model results to case-study field sites will help us to interpret the landscape signature of strike-slip faulting, and to understand

  16. Texture Coding in the Rat Whisker System: Slip-Stick Versus Differential Resonance

    PubMed Central

    Wolfe, Jason; Hill, Dan N; Pahlavan, Sohrab; Drew, Patrick J; Kleinfeld, David; Feldman, Daniel E

    2008-01-01

    Rats discriminate surface textures using their whiskers (vibrissae), but how whiskers extract texture information, and how this information is encoded by the brain, are not known. In the resonance model, whisker motion across different textures excites mechanical resonance in distinct subsets of whiskers, due to variation across whiskers in resonance frequency, which varies with whisker length. Texture information is therefore encoded by the spatial pattern of activated whiskers. In the competing kinetic signature model, different textures excite resonance equally across whiskers, and instead, texture is encoded by characteristic, nonuniform temporal patterns of whisker motion. We tested these models by measuring whisker motion in awake, behaving rats whisking in air and onto sandpaper surfaces. Resonant motion was prominent during whisking in air, with fundamental frequencies ranging from approximately 35 Hz for the long Delta whisker to approximately 110 Hz for the shorter D3 whisker. Resonant vibrations also occurred while whisking against textures, but the amplitude of resonance within single whiskers was independent of texture, contradicting the resonance model. Rather, whiskers resonated transiently during discrete, high-velocity, and high-acceleration slip-stick events, which occurred prominently during whisking on surfaces. The rate and magnitude of slip-stick events varied systematically with texture. These results suggest that texture is encoded not by differential resonant motion across whiskers, but by the magnitude and temporal pattern of slip-stick motion. These findings predict a temporal code for texture in neural spike trains. PMID:18752354

  17. Local decomposition induced by dislocation motions inside tetragonal Al2Cu compound: slip system-dependent dynamics

    NASA Astrophysics Data System (ADS)

    Chen, D.; Ma, X. L.

    2013-11-01

    Dislocations in a crystal are usually classified into several independent slip systems. Motion of a partial dislocation in monometallic crystals may remove or create stacking fault characterized with a partial of a lattice translation vector. However, it is recently known that motion of partial dislocations in complex structure, such as that inside an intermetallic Al2Cu compound, lead to a local composition deviation from its stoichiometric ratio and the resultant structure collapse. Here we report such a local decomposition behaviors are strongly dependent on slip system of dislocations. Under applied external stress, we have studied dislocation motion behaviors in the three independent slip systems of [001](110), [100]() and [110]() within tetragonal Al2Cu crystal by using molecular dynamics method. We found dislocation motions in all these slip systems result in local decomposition but their physical details differ significantly.

  18. Local decomposition induced by dislocation motions inside tetragonal Al(2)Cu compound: slip system-dependent dynamics.

    PubMed

    Chen, D; Ma, X L

    2013-01-01

    Dislocations in a crystal are usually classified into several independent slip systems. Motion of a partial dislocation in monometallic crystals may remove or create stacking fault characterized with a partial of a lattice translation vector. However, it is recently known that motion of partial dislocations in complex structure, such as that inside an intermetallic Al2Cu compound, lead to a local composition deviation from its stoichiometric ratio and the resultant structure collapse. Here we report such a local decomposition behaviors are strongly dependent on slip system of dislocations. Under applied external stress, we have studied dislocation motion behaviors in the three independent slip systems of [001](110), [100]() and [110]() within tetragonal Al2Cu crystal by using molecular dynamics method. We found dislocation motions in all these slip systems result in local decomposition but their physical details differ significantly. PMID:24196169

  19. Local decomposition induced by dislocation motions inside tetragonal Al2Cu compound: slip system-dependent dynamics

    PubMed Central

    Chen, D.; Ma, X. L.

    2013-01-01

    Dislocations in a crystal are usually classified into several independent slip systems. Motion of a partial dislocation in monometallic crystals may remove or create stacking fault characterized with a partial of a lattice translation vector. However, it is recently known that motion of partial dislocations in complex structure, such as that inside an intermetallic Al2Cu compound, lead to a local composition deviation from its stoichiometric ratio and the resultant structure collapse. Here we report such a local decomposition behaviors are strongly dependent on slip system of dislocations. Under applied external stress, we have studied dislocation motion behaviors in the three independent slip systems of [001](110), [100]() and [110]() within tetragonal Al2Cu crystal by using molecular dynamics method. We found dislocation motions in all these slip systems result in local decomposition but their physical details differ significantly. PMID:24196169

  20. Reducing employee slips, trips, and falls during employee-assisted patient activities.

    PubMed

    Staal, Collette; White, Barbra; Brasser, Bruce; LeForge, Larry; Dlouhy, Amie; Gabier, Jeff

    2004-01-01

    Following a remodeling of patient care rooms at Mary Free Bed Rehabilitation Hospital, the nursing staff reported frequent slipping in patient care areas. Data were analyzed and revealed that most slips were occurring during transfer of patients from shower chairs. An extensive literature review was done, and solutions to slipping were sought from areas outside of the healthcare industry. Specifically, ideas were borrowed from the commercial fishing industry and the restaurant industry. Both industries rely heavily on footwear to reduce slipping in the workplace. A trial was initiated with nursing staff members wearing positive-grip shoe covers that can be worn over regular footwear. No slips occurred during the trial. The purpose of this article is to motivate nurses who are involved in transferring patients from shower chairs (often used in rehabilitation settings) to consider the role their footwear has in reducing slips and potential injury. PMID:15598000

  1. Application of slip-line analysis to the mechanical model of active accretionary wedge

    NASA Astrophysics Data System (ADS)

    Song, I.; Lee, H.; Kim, J.

    2012-04-01

    An active accretionary wedge is formed from sediments accreted continuously at a continental margin by a subducting plate and mechanically characterized by a plane-strain compressive frictional flow throughout its entire volume. Continuous deformation induced by incoming sediments raises the distortional stress eventually leading to an ultimate condition known as a critical state. According to the critical taper theory (Davis et al., JGR, 1983), the angle of wedge increases as the incoming materials are accreted into the wedge until it reaches a critical value where the shear force on the basal detachment is in equilibrium with the basal friction. Under this concept, we applied the plastic slip-line theory for the computation of stress and velocity fields throughout the continuously deforming area of the wedge. For the simplicity, we assumed that the tapered wedge overlying a basal décollement fault is described by a perfectly plastic rheology complying with the Coulomb failure criterion and the associated flow rule. A complete description of soil rheology at the critical state requires the determination of stress tensors and velocity vectors at given points within the deforming region. For the boundary condition of stress, the effective normal and shear tractions on the upper surface of wedge are equal to zero, and thus the maximum principal stress acts parallel to the surface. Considering the two-dimensional plane strain deformation, we numerically obtained the slip-line solution for the mean effective stress with respect to the orientation of the maximum principal stress at each intersection point of the potential (conjugate) slip lines given by the Coulomb criterion. Then the maximum shear stress was calculated using the failure criterion. After the stress solution was yielded, the velocity field was determined by the same procedure using the boundary condition of the velocity of incoming sediments obtained from the velocity of subducting plate. Our result

  2. Effect of inherited structures on strike-slip plate boundaries: insight from analogue modelling of the central Levant Fracture System, Lebanon

    NASA Astrophysics Data System (ADS)

    Ghalayini, Ramadan; Daniel, Jean-Marc; Homberg, Catherine; Nader, Fadi

    2015-04-01

    Analogue sandbox modeling is a tool to simulate deformation style and structural evolution of sedimentary basins. The initial goal is to test what is the effect of inherited and crustal structures on the propagation, evolution, and final geometry of major strike-slip faults at the boundary between two tectonic plates. For this purpose, we have undertaken a series of analogue models to validate and reproduce the structures of the Levant Fracture System, a major NNE-SSW sinistral strike-slip fault forming the boundary between the Arabian and African plates. Onshore observations and recent high quality 3D seismic data in the Levant Basin offshore Lebanon demonstrated that Mesozoic ENE striking normal faults were reactivated into dextral strike-slip faults during the Late Miocene till present day activity of the plate boundary which shows a major restraining bend in Lebanon with a ~ 30°clockwise rotation in its trend. Experimental parameters consisted of a silicone layer at the base simulating the ductile crust, overlain by intercalated quartz sand and glass sand layers. Pre-existing structures were simulated by creating a graben in the silicone below the sand at an oblique (>60°) angle to the main throughgoing strike-slip fault. The latter contains a small stepover at depth to create transpression during sinistral strike-slip movement and consequently result in mountain building similarly to modern day Lebanon. Strike-slip movement and compression were regulated by steady-speed computer-controlled engines and the model was scanned using a CT-scanner continuously while deforming to have a final 4D model of the system. Results showed that existing normal faults were reactivated into dextral strike-slip faults as the sinistral movement between the two plates accumulated. Notably, the resulting restraining bend is asymmetric and segmented into two different compartments with differing geometries. One compartment shows a box fold anticline, while the second shows an

  3. Development of a Tactile and Slip Sensor Controlled Prosthetic Hand System

    NASA Astrophysics Data System (ADS)

    Xu, W.; Wang, R. C.; Zhang, J. C.; Jin, D. W.

    2008-10-01

    Supported by the latest sensor and microcontroller technologies, prosthetic hands have been widely used to reclaim the human functionaries. Among these, the most advanced prosthetic hand was controlled by the tactile and EMG singles. However, for a slippery object, attention has to be taken for the inexperienced users who need to control the shrinkage of the wrist flexor carefully. In this paper, the authors presented a prosthetic hand control system using PVDF film sensor to provide both tactile and slip force feedback signals to operate the hand. The PVDF film sensor used for this control system was specifically developed to detect both tactile and slip force between the prosthetic finger and object. The method of distinguishing two signals was described. A prototype system was constructed using a microcontroller to process the signal from the sensor and provide control signal to the motors operate the prosthetic hand. The test result of the prototype device shown that comparing with the one without slippery signal feedback, this system was easy to operate for an inexperienced user.

  4. Basement-driven strike-slip deformation involving a salt-stock canopy system

    NASA Astrophysics Data System (ADS)

    Dooley, Tim; Jackson, Martin; Hudec, Mike

    2016-04-01

    NW-striking basement-involved strike-slip zones have been reported or inferred from the northern Gulf of Mexico (GoM). This interpretation is uncertain, because the effects of strike-slip deformation are commonly difficult to recognize in cross sections. Recognition is doubly difficult if the strike-slip zone passes through a diapir field that complicates deformation, and an associated salt canopy that partially decouples shallow deformation from deep deformation. We use physical models to explore the effects of strike-slip deformation above and below a salt-stock canopy system. Canopies of varying maturity grew from a series of 14 feeders/diapirs located on and off the axis of a dextral basement fault. Strike-slip deformation styles in the overburden vary significantly depending on: (1) the location of the diapirs with respect to the basement fault trace, and; (2) the continuity of the canopy system. On-axis diapirs (where the diapirs lie directly above the basement fault) are typically strongly deformed and pinched shut at depth to form sharp S-shapes, whereas their shallow deformation style is that of a open-S-shaped pop-up structure in a restraining bend. The narrow diapir stem acts as a shear zone at depth. Pull-apart structures form between diapirs that are arranged in a right-stepping array tangental to the basement fault trace. These grade along strike into narrow negative flower structures. Off-axis diapirs (diapirs laterally offset from the basement fault but close enough to participate in the deformation) form zones of distributed deformation in the form of arrays of oblique faults (R shears) that converge along strike onto the narrower deformation zones associated with on-axis diapirs. Above an immature, or patchy, canopy system the strike-slip structures closely match sub canopy structures, with the exception of wrench fold formation where the supracanopy roof is thin. In contrast, the surface structures above a mature canopy system consist of a broad

  5. Cycle Slips Detection in Quad-Frequency Mode: Galileo's Contribution to an Efficient Approach under High Ionospheric Activity

    NASA Astrophysics Data System (ADS)

    Van de Vyvere, Laura; Warnant, René

    2016-04-01

    Cycle slips detection has always been a key issue in phase measurements accuracy, thus impacting positioning precision. Since Galileo is the first constellation to offer four carrier frequencies available in Open Service, we were able to develop an innovative detection algorithm, especially promising in harsh environment like high ionospheric activity. This improves previous dual and triple-frequency methods, whose efficiency was somehow limited in tricky situations, like ionospheric events or particular configurations. In our algorithm, two types of testing quantities were used: triple-frequency Simsky combination and dual-frequency Geometry-Free combination, each one being associated to a suitable detection algorithm. Simsky combination allows to detect almost every configuration, except for cycle slips of the same magnitude, appearing simultaneously on all carriers. Geometry-Free combination is only used to detect this particular case, since it suffers from quick variation of ionospheric delay. Together - through the choice of the most efficient combination alternatives - they enable the detection of any cycle slips configuration. This is now made possible thanks to the availability of data from Galileo's four carriers. The quad-frequency algorithm has been tested on Galileo observations from both GMSD (Japan) and NKLG (Gabon) stations. On the first ones, cycle slips were artificially inserted in order to simulate particular cases and test algorithm robustness. NKLG raw data were used to assess algorithm behaviour for cases met in the equatorial area. Enhanced with a suitable cycle slip correction method and a real-time feature, our algorithm could directly be integrated into the software receiver, enabling the supply of continuous and corrected data to the user. In conclusion, this first quad-frequency cycle slips detection algorithm is obviously a step forward and every Galileo user will indeed be able to benefit from a highly better-quality positioning. With

  6. Update on slip and wear in multi-layer azimuth track systems

    NASA Astrophysics Data System (ADS)

    Juneja, Gunjeet; Kan, Frank W.; Antebi, Joseph

    2006-06-01

    Many antennas, such as the 100-m Green Bank Telescope, use a wheel-on-track systems in which the track segments consist of wear plates mounted on base plates. The wear plates are typically 2 to 3 inches thick and are case hardened or through hardened. The base plates are usually 3 to 4 times thicker than the wear plates and are not hardened. The wear plates are typically connected to the base plates using bolts. The base plates are supported on grout and anchored to the underlying concrete foundation. For some antennas, slip has been observed between the wear plate and base plate, and between the base plate and the grout, with the migration in the wheel rolling direction. In addition, there has been wear at the wear plate/base plate interface. This paper is an update on the evaluation of GBT track retrofit. The paper describes the use of three-dimensional non-linear finite element analyses to understand and evaluate the behavior of (1) the existing GBT wheel-on-track system with mitered joints, and (2) the various proposed modifications. The modifications include welding of the base plate joints, staggering of the wear plate joints from the base plate joints, changing thickness of the wear plate, and increasing bolt diameter and length. Parameters included in the evaluation were contact pressure, relative slip, wear at the wear plate/base plate interface, and bolt shears and moments.

  7. Anthropogenically-Induced Superficial Seismic Activity Modulated By Slow-Slip Events in Guerrero, Mexico

    NASA Astrophysics Data System (ADS)

    Frank, W.; Shapiro, N.; Husker, A. L.; Kostoglodov, V.; Campillo, M.

    2014-12-01

    We use the data of the MASE seismic experiment operated during 2.5 years in Guerrero, Mexico to create a large catalog of seismic multiplets. This catalog is dominated by families of Low-Frequency Earthquakes (LFE) occurring in vicinity of the main subduction interface. In addition to more than one thousand LFE families, we detected nine repeating seismic event families that are located in the upper crust and are anthropogenically induced (AI) by mining blasts. Analysis of the recurrence of these AI events in time shows that their activity significantly increases during the strong Slow-Slip Event (SSE) in 2006. Modeled static stress perturbations induced by the SSE at the surface are ~5 kPa that is on the same order of magnitude as dynamic stress perturbations observed to trigger other low stress drop phenomena, such as tectonic tremor. We propose therefore that strong SSEs in Guerrero impose an extensional regime throughout the continental crust, modifying the stress field near the surface and increasing AI activity. This modulation of the recurrence of the crustal seismic events by the SSE-induced stress might be related to another recent observation: the SSE-induced reduction of seismic velocities linked to nonlinear elastic effects caused by opening of cracks (Rivet et al., 2011, 2014).

  8. Active strike-slip faulting history inferred from offsets of topographic features and basement rocks: a case study of the Arima Takatsuki Tectonic Line, southwest Japan

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2002-01-01

    Geological, geomorphological and geophysical data have been used to determine the total displacement, slip rates and age of formation of the Arima-Takatsuki Tectonic Line (ATTL) in southwest Japan. The ATTL is an ENE-WSW-trending dextral strike-slip fault zone that extends for about 60 km from northwest of the Rokko Mountains to southwest of the Kyoto Basin. The ATTL marks a distinct topographic boundary between mountainous regions and basin regions. Tectonic landforms typically associated with active strike-slip faults, such as systematically-deflected stream channels, offset ridges and fault scarps, are recognized along the ATTL. The Quaternary drainage system shows progressive displacement along the fault traces: the greater the magnitude of stream channel, the larger the amount of offset. The maximum dextral deflection of stream channels is 600-700 m. The field data and detailed topographic analyses, however, show that pre-Neogene basement rocks on both sides of the ATTL are displaced by about 16-18 km dextrally and pre-Mio-Pliocene elevated peneplains are also offset 16-17 km in dextral along the ATTL. This suggests that the ATTL formed in the period between the development of the pre-Mio-Pliocene peneplains and deflection of the Quaternary stream channels. The geological, geomorphological and geophysical evidence presented in this study indicates that (1) the ATTL formed after the mid-Miocene, (2) the ATTL has moved as a dextral strike-slip fault with minor vertical component since its formation to late Holocene and (3) the ATTL is presently active with dextral slip rates of 1-3 mm/year and a vertical component of >0.3 mm/year. The formation of the ATTL was probably related to the opening of the Japan Sea, which is the dominant tectonic event around Japan since mid-Miocene. The case study of the ATTL provides insight into understanding the tectonic history and relationship between tectonic landforms and structures in active strike-slip faults.

  9. Quaternary estimates of average slip-rates for active faults in the Mongolian Altay Mountains: the advantages and assumptions of multiple dating techniques

    NASA Astrophysics Data System (ADS)

    Gregory, L. C.; Walker, R. T.; Thomas, A. L.; Amgaa, T.; Bayasgalan, G.; Amgalan, B.; West, A.

    2010-12-01

    Active faults in the Altay Mountains, western Mongolia, produce surface expressions that are generally well-preserved due to the arid central-Asian climate. Motion along the right-lateral strike-slip and oblique-reverse faults has displaced major river systems by kilometres over millions of years and there are clear scarps and linear features in the landscape along the surface traces of active fault strands. With combined remote sensing and field work, we have identified sites with surface features that have been displaced by tens of metres as a result of cumulative motion along faults. In an effort to accurately quantify an average slip-rate for the faults, we used multiple dating techniques to provide an age constraint for the displaced landscapes. At one site on the Olgiy fault, we applied 10Be terrestrial cosmogenic nuclides (TCN) and uranium-series geochronology on boulder tops and in-situ formed carbonate rinds, respectively. Based on a displacement of approximately 17m, and geochronology results that range from 20-60ky, we resolve a slip-rate of less than 1 mm/yr. We have also applied optically stimulated luminescence (OSL), 10Be TCN, and U-series methods on the Ar Hotol fault. Each of these dating techniques provides unique constraints on the relationship between the ‘age’ of a displaced surface and the actual amount of displacement, and each has inherent assumptions. We will consider the advantages and assumptions made in utilising these techniques in western Mongolia- e.g. U-series dating of carbonate rinds can provide a minimum age for alluvial fan deposition, and inheritance must be considered when using TCN techniques on boulder tops. This will be put into the context of estimating accurate and geologically relevant slip-rates, and improving our understanding of the active deformation of the Mongolian Altay.

  10. The role of latent and active failures in workplace slips, trips and falls: an information processing approach.

    PubMed

    Bentley, Tim

    2009-03-01

    The vast majority of the published workplace slips, trips and falls (STF) literature is exceedingly narrow in its focus and often ignores wider systems issues in workplace STF aetiology. There is little recognition within the published literature of the importance of latent failures or the upstream organisational and cultural contexts within which workplace STF occur. This is unfortunate, as a systems approach to workplace STF analysis, that is inclusive of latent design and work organisation factors that often shape worker behaviour patterns related to STF risk (e.g. rushing, risk taking), is fundamental to the development of effective prevention measures. The aims of this paper are to provide an understanding of workplace STF causation that is cognisant of the potential role of both active and latent failures in STF causation. The paper presents an ergonomics model for workplace STF analysis that highlights information processing in STF aetiology, the STF incident process and the interaction between latent and active failures in STF causation. The paper draws upon ergonomics research conducted in a range of occupational contexts to illustrate the key features of the model as it applies to workplace STF. Implications of the model for analysis and prevention of STF are discussed. PMID:18501330

  11. Numerical model of formation of a 3-D strike-slip fault system

    NASA Astrophysics Data System (ADS)

    Chemenda, Alexandre I.; Cavalié, Olivier; Vergnolle, Mathilde; Bouissou, Stéphane; Delouis, Bertrand

    2016-01-01

    The initiation and the initial evolution of a strike-slip fault are modeled within an elastoplasticity constitutive framework taking into account the evolution of the hardening modulus with inelastic straining. The initial and boundary conditions are similar to those of the Riedel shear experiment. The models first deform purely elastically. Then damage (inelastic deformation) starts at the model surface. The damage zone propagates both normal to the forming fault zone and downwards. Finally, it affects the whole layer thickness, forming flower-like structure in cross-section. At a certain stage, a dense set of parallel Riedel shears forms at shallow depth. A few of these propagate both laterally and vertically, while others die. The faults first propagate in-plane, but then rapidly change direction to make a larger angle with the shear axis. New fault segments form as well, resulting in complex 3-D fault zone architecture. Different fault segments accommodate strike-slip and normal displacements, which results in the formation of valleys and rotations along the fault system.

  12. Modelling a strike-slip fault system affecting porous carbonates in Favignana Island (Sicily, southern Italy)

    NASA Astrophysics Data System (ADS)

    Cilona, A.; Tondi, E.; Agosta, F.; Johnson, G.; Shackleton, R.

    2012-12-01

    Investigating the deformation processes as well as the characteristics and distribution of their end-products is a crucial issue to improve geo-fluid exploitation in carbonate reservoirs (≈50% of natural geo-fluids). Indeed, besides the primary controls on the petrophysical properties of limestones, which are due to nature and organization/shape of the constituent elements (i.e. grains, pores, cement, clay minerals), both containment and migration of fluids in these rocks are influenced by fault zones and fractures. In this contribution we integrate quantitative structural analysis and numerical modelling approaches aiming at testing a new workflow useful to create a 3D discrete fracture network (DFN) model of a reservoir starting from outcrop data collected in Favignana Island (Sicily, southern Italy). The presence of several quarries in the Island provides 3D exposures of ≈25 m-thick Lower-Pleistocene high-porosity grainstones crosscut by two conjugate sets of strike-slip faults. This fault system, documented by Tondi et al. (2012), is comprised of three types of structure: single compactive shear bands (CSB); zones of bands (ZB); and, faults. CSBs are narrow tabular features with porosity less than the surrounding host rocks, and have thicknesses and displacements on the order of a few mm. The growth process for these structures involves localizing further deformation within zones of closely-spaced CSBs and, possibly, along continuous slip surfaces within fault rocks overprinting older ZBs. The transitions from one growth step to another are recorded by different values of the dimensional parameters (i.e. length, thickness and displacement) for the structures. These transitions are also reflected by the ratios and distributions of the dimensional parameters. The DFN model was built by means of the Fracture Modelling module of the commercial software package Move from Midland Valley©. The analysis of an aerial photo was performed firstly to delimit the

  13. Temporal Slip Variation of the Sierra Nevada Frontal Fault System and Effects on Landscape Evolution

    NASA Astrophysics Data System (ADS)

    Kemp, C. D.; Wakabayashi, J.

    2008-12-01

    Temporal variability of vertical separation- and slip-rates determined by new geochronologic and geomorphic studies provides data to better understand the tectonic and geomorphic evolution of the Sierra Nevada. The Quincy and Lake Almanor region of the northern Sierra Nevada hosts ideal field relations to examine both long- and short-term slip- and vertical-separation rates of the Eastern Sierra Frontal Fault system (Frontal Fault system) and their relation to landscape evolution. We report initial results of the study. Geochronology provides key data to determine 1) the rate of uplift-related stream incision 2) the rate of vertical separation of the Frontal Fault system 3) the northern Sierra Nevada landscape response to temporal rate variations. Forty-one Late Cenozoic volcanic deposits yield K-Ar conventional and Ar-Ar incremental heating ages between .15 Ma and 3.3 Ma; another ten Ar-Ar ages of rocks from the Mehrten and Yana Formations are pending and the expected age range for these samples is ~2.8 Ma to ~5 Ma respectively. The present northern Sierra Nevada landscape is characterized by high plateau-like ridges capped by Yana or Mehrten volcanics above deeply incised canyons. Field and geomorphic relations reveal a reverse stratigraphic sequence of terrace-like remnants of basaltic or andesitic composition in the North Fork Feather River canyon. Ar-Ar ages of the inset volcanics indicate rapid incision since 2.8 Ma with rates of incision increasing into the present. Similarly, field and geomorphic relations of older rocks reveal incipience and evolution of relief generation. Rocks of the ~5 Ma Mehrten Formation are occasionally underlain by Eocene to Miocene "auriferous" gravels deposited by trans-Sierran paleochannels; field relations of the Mehrten Fm. and gravels indicate low-relief paleotopography at Miocene-Pliocene time. Likewise, the Yana Fm. indicates similar paleotopography at 2.8 Ma thus constraining timing of relief production to post

  14. Active flexural-slip faulting: A study from the Pamir-Tian Shan convergent zone, NW China

    NASA Astrophysics Data System (ADS)

    Li, Tao; Chen, Jie; Thompson, Jessica A.; Burbank, Douglas W.; Yang, Xiaodong

    2015-06-01

    The flexural-slip fault (FSF), a type of secondary fault generated by bed-parallel slip, occurs commonly and plays an important role in accommodating fold growth. Although the kinematics and mechanics of FSFs are well studied, relatively few field observations or geometric models explore its geomorphic expression. In the Pamir-Tian Shan convergent zone, NW China, suites of well-preserved FSF scarps displace fluvial terraces in the Mingyaole and Wulagen folds. Integrating interpretations of Google Earth images, detailed geologic and geomorphic mapping, and differential GPS measurements of terrace surfaces, we summarize geomorphic features that typify these faults and create kinematic models of active flexural-slip faulting. Our study indicates the following: (i) FSF scarps commonly occur near synclinal hinges, irrespective of whether (a) the dip direction of beds on either side of the hinge is unidirectional or in opposite directions, (b) the hinge is migrating or fixed, or (c) the hinge shape is narrow and angular or wide and curved. (ii) Active FSFs are likely to produce higher scarps on steeper beds, whereas lower or no topographic scarps typify gentler beds. (iii) Tilt angles of the terrace surface displaced above FSFs progressively decrease farther away from the hinge, with abrupt changes in slope coinciding with FSF scarps; the changes in tilt angle and scarp height have a predictable geometric relationship. (iv) Active FSFs can accommodate a significant fraction of total slip and play a significant role in folding deformation. (v) Active FSFs may be used to assess seismic hazards associated with active folds and associated blind thrusts.

  15. Deformation pattern around the conjoining strike-slip fault systems in the Basin and Range, southeast Nevada: The role of strike-slip faulting in basin formation and inversion

    NASA Astrophysics Data System (ADS)

    Çakir, Mehmet; Aydin, Atilla; Campagna, David J.

    1998-06-01

    Within the extensional regime of the Basin and Range, strike-slip faults create a regional pattern of opposing sense of fault systems. The relationship between these faults and other deformational features nearby is enigmatic. This paper addresses a diverse assemblage of contractional and extensional structures reflecting local uplift and subsidence, respectively, at the junction of two large Neogene strike-slip faults in southeastern Nevada, the right-lateral Las Vegas Valley shear zone and the left-lateral Bitter Spring Valley fault of the Lake Mead fault system. First, a middle Miocene lacustrine carbonate basin, the Bitter Ridge-Lovell Wash carbonate basin, formed north of the strike-slip faults. Second, the lacustrine basin inverted locally, while sediments accumulated south of the strike-slip faults. Third, the study area was deformed by north-northeast trending, high-angle oblique faults with normal and left-slip components. The results, both from field observations and numerical modeling of the intersecting strike-slip faults, show that the Las Vegas Valley shear zone and the Bitter Spring Valley fault may have produced the basin in the north and its intense contractional deformation as well as the southward shift of deposition during the inversion event. We conclude that conjoining strike-slip fault systems can promote localized vertical tectonics and lead to basin formation and uplift right next to each other. Subsequent inversion of the earlier basinal deposits, however, requires a reversal in the sense of slip across the Las Vegas Valley shear zone and a change in the regional stress system.

  16. Mesoscopic structure of the Punchbowl Fault, Southern California and the geologic and geophysical structure of active strike-slip faults

    NASA Astrophysics Data System (ADS)

    Schulz, Steven E.; Evans, James P.

    2000-07-01

    We examine the distribution, density, and orientation of outcrop-scale structures related to the Punchbowl Fault, an exhumed ancient trace of the San Andreas Fault, southern California, in order to determine the structure of the fault zone. The Punchbowl Fault has 44 km of right-lateral slip, and cuts the Cretaceous Pelona Schist in the study area. The mesoscopic structures examined include fractures, small faults, and veins; they were inventoried using scan lines at closely spaced stations along three strike-perpendicular traverses 200-250 m long across the fault. The fault zone thickness is a function of the type of structure measured. Slip along narrow (<2 m wide) ultracataclasite cores of the faults results in foliation reorientation over a distance of 50 m from the cores: fracture and fault densities appear to increase 50-80 m from the fault cores, and vein densities are highly variable across the fault zone. Fractures and faults in the damaged zone have a variety of orientations, but most are at high angles to the main fault zone. When coupled with previous geochemical and microstructural data, these data show that large-displacement faults of the San Andreas system, are up to 200-250 m thick, and enclose zones of mineralogic and geochemical alteration that are 20-30 m thick. Extreme slip localization occurs over zones 1-5 m thick. When reconciled with geophysical imaging, our data suggest that trapped headwaves travel in the damaged zone, and that some aftershock events produce slip on faults and fractures, which often have orientations very different from the principal slip surfaces.

  17. Combined Effect of Hall and Ion-Slip Currents on Unsteady MHD Couette Flows in a Rotating System

    NASA Astrophysics Data System (ADS)

    Jha, Basant K.; Apere, Clement A.

    2010-10-01

    The unsteady MHD Couette flows of a viscous incompressible electrically conducting fluid between two parallel plates in a rotating system are studied taking hall and ion-slip currents into consideration. The relevant equations are solved analytically using the Laplace transform techniques. A unified closed form analytical expressions for the velocity and the skin friction for the cases; when the magnetic lines of force are fixed relative to the fluid or to the moving plate are derived. The solution obtained shows that the inclusion of Hall and ion-slip currents gives some interesting results. It is found that the influence of the Hall and ion slip parameters have a reducing effect on the magnitude of the secondary velocity especially when the magnetic lines of force are fixed relative to the moving plate. It is also interesting to note that the presence of Hall and ion-slip currents led to an increase in the time it took both the primary and the secondary velocities to achieve their steady state values. On the other hand, the resultant skin friction on the moving plate decreases with an increase in both the Hall and ion-slip parameters when the magnetic field is fixed relative to the fluid, while the opposite behaviour is noticed the magnetic field is fixed relative to the moving plate.

  18. Fabrication of Activated Rice Husk Charcoal by Slip Casting as a Hybrid Material for Water Filter Aid

    NASA Astrophysics Data System (ADS)

    Tuaprakone, T.; Wongphaet, N.; Wasanapiarnpong, T.

    2011-04-01

    Activated charcoal has been widely used as an odor absorbent in household and water purification industry. Filtration equipment for drinking water generally consists of four parts, which are microporous membrane (porous alumina ceramic or diatomite, or porous polymer), odor absorbent (activated carbon), hard water treatment (ion exchange resin), and UV irradiation. Ceramic filter aid is usually prepared by slip casting of alumina or diatomite. The membrane offers high flux, high porosity and maximum pore size does not exceed 0.3 μm. This study investigated the fabrication of hybrid activated charcoal tube for water filtration and odor absorption by slip casting. The suitable rice husk charcoal and water ratio was 48 to 52 wt% by weight with 1.5wt% (by dry basis) of CMC binder. The green rice husk charcoal bodies were dried and fired between 700-900 °C in reduction atmosphere. The resulting prepared slip in high speed porcelain pot for 60 min and sintered at 700 °C for 1 h showed the highest specific surface area as 174.95 m2/g. The characterizations of microstructure and pore size distribution as a function of particle size were investigated.

  19. Slip Kits.

    ERIC Educational Resources Information Center

    Coombes, S. D.

    1979-01-01

    Discusses the process of developing the Science Lessons from Industrial Processes (SLIP) kits by 16 British science teachers. The content, applicability, and components of these kits (based upon local industries) are also included. (HM)

  20. Preceding seismic activity and slow slip events in the source area of the 2011 Mw 9.0 Tohoku-Oki earthquake: a review

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Yoshida, Keisuke

    2015-12-01

    The 2011 Tohoku-Oki earthquake ruptured a large area of the megathrust east of NE Japan. The earthquake's magnitude was 9.0, substantially larger than predicted. It is important to know what occurred in the source area prior to this great megathrust earthquake to improve understanding of the nucleation processes of large earthquakes and risk assessments in subduction zones. Seafloor observation data revealed the existence of two extremely large slip patches: one just updip of the mainshock hypocenter and the other 80-100 km to the north near the trench axis. For 70-90 years before 2003, M > 6 events and slips of M > c. 7 events on the megathrust occurred in the areas surrounding these two large slip patches. Seismic activity had increased since at least 2003 in the downdip portion of the source area of the Tohoku-Oki earthquake. In addition, long-term accelerated slow slip occurred in this downdip portion of the source area in the decades before the Tohoku-Oki earthquake. About 1 month before the earthquake, a slow slip event (SSE) took place at relatively shallow depths between the two large slip patches, accompanied by foreshock activity. Both the slow slip and foreshocks propagated from north to south toward the southern large slip patch. Two days before the earthquake, an M 7.3 foreshock and an associated postseismic slip began at relatively deep depths in the megathrust between the two large slip patches. In addition, a slow slip type event seems to have occurred approximately half a day after the M 7.3 foreshock near the mainshock hypocenter. This slow slip event and the foreshock activity again propagated from north to south toward the mainshock hypocenter. These long- and short-term preceding seismic and aseismic slip gradually reduced the interplate coupling, increased shear stresses at the two large slip patches (i.e., two strong asperity patches), and finally led to the rupture of the great Tohoku-Oki earthquake.

  1. Palaeopermeability structure within fault-damage zones: A snap-shot from microfracture analyses in a strike-slip system

    NASA Astrophysics Data System (ADS)

    Gomila, Rodrigo; Arancibia, Gloria; Mitchell, Thomas M.; Cembrano, Jose M.; Faulkner, Daniel R.

    2016-02-01

    Understanding fault zone permeability and its spatial distribution allows the assessment of fluid-migration leading to precipitation of hydrothermal minerals. This work is aimed at unraveling the conditions and distribution of fluid transport properties in fault zones based on hydrothermally filled microfractures, which reflect the ''frozen-in'' instantaneous advective hydrothermal activity and record palaeopermeability conditions of the fault-fracture system. We studied the Jorgillo Fault, an exposed 20 km long, left-lateral strike-slip fault, which juxtaposes Jurassic gabbro against metadiorite belonging to the Atacama Fault System in northern Chile. Tracings of microfracture networks of 19 oriented thin sections from a 400 m long transect across the main fault trace was carried out to estimate the hydraulic properties of the low-strain fault damagezone, adjacent to the high-strain fault core, by assuming penny-shaped microfractures of constant radius and aperture within an anisotropic fracture system. Palaeopermeability values of 9.1*10-11 to 3.2*10-13 m2 in the gabbro and of 5.0*10-10 to 1.2*10-13 m2 in the metadiorite were determined, both decreasing perpendicularly away from the fault core. Fracture porosity values range from 40.00% to 0.28%. The Jorgillo Fault has acted as a left-lateral dilational fault-bend, generating large-scale dilation sites north of the JF during co-seismic activity.

  2. Tsunami Hazards From Strike-Slip Earthquakes

    NASA Astrophysics Data System (ADS)

    Legg, M. R.; Borrero, J. C.; Synolakis, C. E.

    2003-12-01

    Strike-slip faulting is often considered unfavorable for tsunami generation during large earthquakes. Although large strike-slip earthquakes triggering landslides and then generating substantial tsunamis are now recognized hazards, many continue to ignore the threat from submarine tectonic displacement during strike-slip earthquakes. Historical data record the occurrence of tsunamis from strike-slip earthquakes, for example, 1906 San Francisco, California, 1994 Mindoro, Philippines, and 1999 Izmit, Turkey. Recognizing that strike-slip fault zones are often curved and comprise numerous en echelon step-overs, we model tsunami generation from realistic strike-slip faulting scenarios. We find that tectonic seafloor uplift, at a restraining bend or"pop-up" structure, provides an efficient mechanism to generate destructive local tsunamis; likewise for subsidence at divergent pull-apart basin structures. Large earthquakes on complex strike-slip fault systems may involve both types of structures. The California Continental Borderland is a high-relief submarine part of the active Pacific-North America transform plate boundary. Natural harbors and bays created by long term vertical motion associated with strike-slip structural irregularities are now sites of burgeoning population and major coastal infrastructure. Significant local tsunamis generated by large strike-slip earthquakes pose a serious, and previously unrecognized threat. We model several restraining bend pop-up structures offshore southern California to quantify the local tsunami hazard. Maximum runup derived in our scenarios ranges from one to several meters, similar to runup observed from the 1994 Mindoro, Philippines, (M=7.1) earthquake. The runup pattern is highly variable, with local extremes along the coast. We only model the static displacement field for the strike-slip earthquake source; dynamic effects of moving large island or submerged banks laterally during strike-slip events remains to be examined

  3. Active upper plate thrust faulting in regions of low plate interface coupling, repeated slow slip events, and coastal uplift: Example from the Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Mountjoy, Joshu J.; Barnes, Philip M.

    2011-01-01

    Contractional fore-arc faulting and deformation is a characteristic feature of many subduction systems. Definition of the three-dimensional geometry and displacement rates of active, upper plate, out-of-sequence thrust faults along ˜250 km of the upper Hikurangi Margin enables us to examine the relationship between fore-arc deformation and the subduction interface in light of interseismic coupling estimates and distribution of slow slip events, both modeled from GPS measurements. These mid-fore-arc structures include the seaward vergent, outer shelf Lachlan and Ariel faults, with vertical separation rates up to 5 mm/yr, and several other major inner shelf faults with rates that are up to 3.8 mm/yr and comparable with Holocene coastal uplift rates. Seismic reflection imaging and geometric projection of these faults at depth indicate that they splay from the region of the plate interface where geodetic inversions for interseismic coupling and slow slip events suggest that the plate boundary undergoes aseismic slip. This observation may indicate either (1) that frictional properties and interseismic coupling on the plate interface are independent and unrelated to the active splay fault deformation in the inner-middle fore arc or (2) that the active splay faulting reflects long-term mechanical coupling related to higher shear stress, or the relative yield strength of the plate interface to the overriding plate, and that the current pattern of interseismic coupling may not be persistent over geological time scales of 20 ka. We compare structure and processes on the northern Hikurangi and Costa Rican margins and find similarities and significant differences astride these subduction systems.

  4. Dynamics of phase slips in systems with time-periodic modulation

    NASA Astrophysics Data System (ADS)

    Gandhi, Punit; Knobloch, Edgar; Beaume, Cédric

    2015-12-01

    The Adler equation with time-periodic frequency modulation is studied. A series of resonances between the period of the frequency modulation and the time scale for the generation of a phase slip is identified. The resulting parameter space structure is determined using a combination of numerical continuation, time simulations, and asymptotic methods. Regions with an integer number of phase slips per period are separated by regions with noninteger numbers of phase slips and include canard trajectories that drift along unstable equilibria. Both high- and low-frequency modulation is considered. An adiabatic description of the low-frequency modulation regime is found to be accurate over a large range of modulation periods.

  5. Slip rates and seismic potential on the East Anatolian Fault System using an improved GPS velocity field

    NASA Astrophysics Data System (ADS)

    Aktug, B.; Ozener, H.; Dogru, A.; Sabuncu, A.; Turgut, B.; Halicioglu, K.; Yilmaz, O.; Havazli, E.

    2016-03-01

    The East Anatolian Fault System (EAFS) is the second major fault system in Turkey, following the North Anatolian Fault System (NAFS). Unlike the NAFS, which produced 11 large earthquakes in the last ∼75 years, the EAFS has been relatively quiet during the same period of time. While historical records show that the EAFS has the potential to produce large earthquakes, the fault slip rates on the EAFS were not studied in detail, and were not quantified sufficiently. This is possibly due to the relatively low seismicity and slow slip-rates of the EAFS with respect to the NAFS. However, the determination of the slip rates of the EAFS is equally important in order to understand the kinematics of the Anatolian plate. In this study, we collected and analyzed new survey-type GPS data, and homogeneously combined published velocities from other studies, to form the most complete GPS data set covering the EAFS. In particular, continuous GPS observations were utilized for the first time to study the northern part of the EAFS. The results of the analysis give well-constrained slip rates of the northwestern segments of the EAFS, which is further connected to the Dead Sea Fault System (DSFS) in the south. The results show that while the slip rate of the EAFS is nearly constant (∼10 mm/yr) to the north of Türkoğlu, it then decreases to 4.5 mm/yr in the south. The slip rate on the northern part of the Dead Sea Fault System (DSFS) was also found to be 4.2 ± 1.3 mm/yr, consistent with earlier studies. The contraction rates along the EAFS are below 5 mm/yr, except for the northernmost part near Karliova, where it reaches a maximum value of 6.3 ± 1.0 mm/yr. The results also show that two well-known seismic gaps across the EAFS, Palu-Sincik and Çelikhan-Türkoğlu segments, have slip deficits of 1.5 m and 5.2 m and have the potential to produce earthquakes with magnitudes of Mw7.4 and Mw7.7, respectively.

  6. Seismic evidence of active strike-slip faulting in the external Gulf of Cadiz (SW Iberian Margin)

    NASA Astrophysics Data System (ADS)

    Bartolome, R.; Gràcia, E.; Stich, D.; Martinez-Loriente, S.; Klaeschen, D.; Masana, E.; Diez, S.; Lo Iacono, C.; Moreno, X.; Zitellini, N.; Manuel, A.; Dañobeitia, J.

    2009-12-01

    The Gulf of Cadiz (GC) hosts the present-day NW-SE plate convergence between Eurasia and Africa Plates west of the Straits of Gibraltar at a rate about 4 mm/yr. The convergence is accommodated over a wide and diffuse deformation zone with moderate magnitude seismic activity. Nevertheless, some of the largest events in Western Europe occurred in the GC, such as the 1755 Lisbon (Mw 8.5) and 1969 Horseshoe (Mw 7.0) earthquakes. Recently published swath-bathymetric compilation in the GC area allowed the identification of several WNW-ESE trending SWIM lineaments (SL), extending over a total length of 600 km. Analogue modelling of topographic features along the SL indicates that the structures are compatible with a dextral strike-slip movement. The concentration of these dextral strike-slip faults along a wide band, the SWIM Fault Zone (SFZ), has been proposed as the present-day EUR-AFR plate boundary. This contribution seeks to: 1) characterizing the active SL seismically; 2) establishing the dextral movement of the SL; 3) identifying new WNW-ESE active dextral strike-slip faults off the SFZ; and 4) providing additional constraints on the tectonics and dynamics of the GC. Two different datasets have been used in this work: 1) 5 multichannel (3 of them pre-stack depth migrated) and ultra-high resolution (parametric sounder TOPAS) seismic profiles, acquired in 2006 within the framework of the SWIM project, and 2) moment tensor inversion of 4 earthquakes (Mw 3.8 to 6.0), ranging from 8 to 50 km depth, from the Spanish IGN catalogue. We present 4 transects of MCS and TOPAS data crossing the SL showing detailed images of the shallow and deep crustal structure. TOPAS images provide evidence of recent activity in a “flower structure” morphology associated with strike-slip faults in the SL. MCS data suggest that the Neogene and Quaternary convergence between African and Eurasian plates has also been absorbed by lateral strike-slip faults going at least up to 10 km depth

  7. Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ 36Cl cosmogenic nuclide dating of exhumed fault-plane.

    NASA Astrophysics Data System (ADS)

    Tesson, Jim; Benedetti, Lucilla; Pucci, Stefano; Villani, Fabio; Bourles, Didier; Keddadouche, Karim; Aumaitre, Georges

    2016-04-01

    with the ages of seismic events retrieved from trenching paleoseismological studies performed on fault segments also belonging to the Middle Aterno fault system. Those results thus suggest that the 50 km long fault-system (from the Paganica fault to the Sulmona fault) entirely ruptured in a sequence of events between 4.5 and 5.5 ka. During these periods of intense seismic activity, the associated slip-rate increases up to 3 mm/yr on those faults. Those results shed new light about the seismogenic potential of this fault-system and bring crucial data for the seismic hazard assessment of this area.

  8. Sag-ponding and its Significance in determining Paleo-seismic events along the active strike- slip fault

    NASA Astrophysics Data System (ADS)

    Li, C.; Zhang, P.; Yuan, D.

    2007-12-01

    During the development of one active fault, we really want to know how it behaves and what it will do next. This mostly depends on the record and preservation of the information showing the action of the fault. Sparse young sediments or sediments with coarse grain along most of big strike-slip faults make it hard record and preserve the vestige of the paleo-seismic events. This extremely restricts the development of the Paleo-seismic research. Sag-ponding as well as the deposits in ponds, which are formed by the movement of the fault, can help settling the difficulty. Periodic sag-ponding is a feature to which should be paid more attention along the strike-slip fault, it can develop a pond to capture plenty fine sediments which well record the action of the faults. Sag-ponding can easily be found on the main active strike-slip faults in northern and eastern Tibet. By disclosing the sag-ponding depositions with 3-D excavations, sediment distribution and characters of relevant sag-ponds, and the relation between the sag-ponding and faulting were discussed. 1. Mechanism of the formation of the sag-pond When the valleys and ridges intersecting with the fault are displaced, the fault scarps will block the flow of the streams cut by the fault, or make the gullies develop ancon-like bend. This would form a space for water-storage, and thus a sag-pond comes into being. If the fault behaves like this many times, multi-sag-ponding will occur. 2. Rhythmic sag-ponding deposition features and stratigraphic sequence (1) Vertical characteristics. Observed from the stratigraphic profiles disclosed by the excavation, stratigraphic sequence shows good rhythms. There are several rhythms in each pond, and one rhythm is composed of the lower coarse layers and the upper fine layers. That is, the grains are coarser below and finer upward. (2) Transverse variation. In the direction parallel to the fault, the deposition center of each sag-pond appears regular movement, or migration

  9. The influence of volcanism on fluvial depositional systems in a Cenozoic strike-slip basin, Denali fault system, Yukon Territory, Canada

    SciTech Connect

    Cole, R.B.; Ridgway, K.D. )

    1993-01-01

    The depositional history of the Eocene-Oligocene Burwash strike-slip basin is characterized by a transition from non-volcanic clastic sedimentation of the Amphitheater Formation to deposition of lavas and volcaniclastic rocks of the overlying lower Wrangell volcanic sequence. The purpose of this paper is twofold: (1) to document the contemporaneous fluvial and volcanic depositional history of a nonmarine strike-slip basin, and (2) to discuss the transition from non-volcanic to volcanic deposition in the context of strike-slip basin evolution. The authors indicate that the onset of volcanism within strike-slip basins can result in major reorganizations of drainage systems as well as changes in sediment sources.

  10. Polyphase (Miocene-Pleistocene?) slip on the South Tibetan Fault system in the Dhaulagiri Himalaya

    NASA Astrophysics Data System (ADS)

    McDermott, J. A.; Hodges, K.; van Soest, M. C.

    2009-12-01

    The major detachments of the South Tibetan fault system (STFS) define a physiographic transition that can be traced along most of the length of the Himalayan orogen. The STFS has been assigned an Early-Middle Miocene initiation age, but recent geomorphic, structural and thermochronologic studies suggest that extensional deformation may have continued into the Pliocene and even Pleistocene epochs along some strands. Our recent work in the Kali Gandaki and Myagdi valleys of central Nepal (28°30'N-28°40'N; 83°20'E-83°45'E) adds to the mounting evidence for young STFS displacement. . The previously unmapped “Larjung detachment” is a low-angle (~15-20°), north-dipping structure that crops out within Cambrian(?) greenschist-facies calc-silicate rocks of Tibetan Sedimentary Sequence in the Dhaulagiri Himalaya. This detachment is roughly 2 kilometers structurally above and less steeply dipping than the previously mapped basal structure of the STFS in the region, the Annapurna detachment (AD). Our observations in the Kali Gandaki and Myagdi valleys reveal that the Larjung detachment expresses as a 1- to 10-m thick, brittle-ductile, shear zone. In the Myagdi valley, ductile fabrics indicate oblique slip on this structure in the direction N62°E, with normal and dextral components. On the basis of structural similarities, we link the Larjung detachment to the Machhapuchhare detachment in the Modi Khola drainage and the Phu detachment in the Marsyandi drainage farther east in the Annapurna Himalaya. We have collected a suite of samples in both the Kali Gandaki and Myagdi valleys for low-temperature thermochronometry aimed at constraining the ages of various strands of the STFS in the Dhaulagiri Himalaya. Preliminary (U-Th)/He dating of single crystals of zircon and apatite below the Larjung detachment exhibit consistently young cooling ages (<3.4 Ma). We found no statistically significant evidence of a distinctive age discontinuity across the AD, implying that the

  11. Slip rates along active faults estimated with cosmic-ray exposure dates: Application to the Bogd fault, Gobi-Altaï, Mongolia

    NASA Astrophysics Data System (ADS)

    Ritz, J. F.; Brown, E. T.; Bourlès, D. L.; Philip, H.; Schlupp, A.; Raisbeck, G. M.; Yiou, F.; Enkhtuvshin, B.

    1995-11-01

    Dating morphological features displaced along active faults presents a major difficulty in evaluation of slip rates. We used in-situ produced 10 Be to calculate minimum ages for alluvial surfaces misaligned by movement along a major active fault in the Gobi-Altaï (western Mongolia). The maximum slip rate of ≈1.2 mm/yr suggested by this method contrasts strongly with rates of ≈20 mm/yr that we estimated by correlation of alluvial deposition with warm humid periods associated with the last glacial termination estimated to have occurred about 12 ka in western Tibet. The 10Be-based slip rate indicates that strong earthquakes can occur along faults with low slip rates and demonstrates the contribution of cosmic-ray exposure dating in Quaternary tectonic analyses.

  12. The Slip Hypothesis: Tactile Perception and its Neuronal Bases.

    PubMed

    Schwarz, Cornelius

    2016-07-01

    The slip hypothesis of epicritic tactile perception interprets actively moving sensor and touched objects as a frictional system, known to lead to jerky relative movements called 'slips'. These slips depend on object geometry, forces, material properties, and environmental factors, and, thus, have the power to incorporate coding of the perceptual target, as well as perceptual strategies (sensor movement). Tactile information as transferred by slips will be encoded discontinuously in space and time, because slips sometimes engage only parts of the touching surfaces and appear as discrete and rare events in time. This discontinuity may have forced tactile systems of vibrissae and fingertips to evolve special ways to convert touch signals to a tactile percept. PMID:27311927

  13. Mechanical Evolution and Dynamics of Decollement Slip in Contractional Systems: Correlating Macro- and Micro-Scale Processes in Particle Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Morgan, J. K.

    2014-12-01

    Particle-based numerical simulations allow detailed investigations of small-scale processes and mechanisms associated with fault initiation and slip, which emerge naturally in such models. This study investigates the evolving mechanical conditions and associated micro-mechanisms during transient slip on a weak decollement propagating beneath a growing contractional wedge (e.g., accretionary prism, fold and thrust belt). The models serve as analogs of the seismic cycle, although lacking full earthquake dynamics. Nonetheless, the mechanical evolution of both decollement and upper plate can be monitored, and correlated with the particle-scale physical and contact properties, providing insights into changes that accompany such stick-slip behavior. In this study, particle assemblages consolidated under gravity and bonded to impart cohesion, are pushed at a constant velocity above a weak, unbonded decollement surface. Forward propagation of decollement slip occurs in discrete pulses, modulated by heterogeneous stress conditions (e.g., roughness, contact bridging) along the fault. Passage of decollement slip resets the stress along this horizon, producing distinct patterns: shear stress is enhanced in front of the slipped decollement due to local contact bridging and fault locking; shear stress minima occur immediately above the tip, denoting local stress release and contact reorganization following slip; more mature portions of the fault exhibit intermediate shear stress, reflecting more stable contact force distributions and magnitudes. This pattern of shear stress pre-conditions the decollement for future slip events, which must overcome the high stresses at the fault tip. Long-term slip along the basal decollement induces upper plate contraction. When upper plate stresses reach critical strength conditions, new thrust faults break through the upper plate, relieving stresses and accommodating horizontal shortening. Decollement activity retreats back to the newly formed

  14. Dynamics of phase slips in systems with time-periodic modulation.

    PubMed

    Gandhi, Punit; Knobloch, Edgar; Beaume, Cédric

    2015-12-01

    The Adler equation with time-periodic frequency modulation is studied. A series of resonances between the period of the frequency modulation and the time scale for the generation of a phase slip is identified. The resulting parameter space structure is determined using a combination of numerical continuation, time simulations, and asymptotic methods. Regions with an integer number of phase slips per period are separated by regions with noninteger numbers of phase slips and include canard trajectories that drift along unstable equilibria. Both high- and low-frequency modulation is considered. An adiabatic description of the low-frequency modulation regime is found to be accurate over a large range of modulation periods. PMID:26764781

  15. Aseismic Slip Events along the Southern San Andreas Fault System Captured by Radar Interferometry

    SciTech Connect

    Vincent, P

    2001-10-01

    A seismic slip is observed along several faults in the Salton Sea and southernmost Landers rupture zone regions using interferometric synthetic aperture radar (InSAR) data spanning different time periods between 1992 and 1997. In the southernmost Landers rupture zone, projecting south from the Pinto Mountain Fault, sharp discontinuities in the interferometric phase are observed along the sub-parallel Burnt Mountain and Eureka Peak Faults beginning three months after the Landers earthquake and is interpreted to be post-Landers after-slip. Abrupt phase offsets are also seen along the two southernmost contiguous 11 km Durmid Hill and North Shore segments of the San Andreas Fault with an abrupt termination of slip near the northern end of the North Shore Segment. A sharp phase offset is seen across 20 km of the 30 km-long Superstition Hills Fault before phase decorrelation in the Imperial Valley along the southern 10 km of the fault prevents coherent imaging by InSAR. A time series of deformation interferograms suggest most of this slip occurred between 1993 and 1995 and none of it occurred between 1992 and 1993. A phase offset is also seen along a 5 km central segment of the Coyote Creek fault that forms a wedge with an adjoining northeast-southwest trending conjugate fault. Most of the slip observed on the southern San Andreas and Superstition Hills Faults occurred between 1993 and 1995--no slip is observed in the 92-93 interferograms. These slip events, especially the Burnt Mountain and Eureka Peak events, are inferred to be related to stress redistribution from the June, 1992 M{sub w} = 7.3 Landers earthquake. Best-fit elastic models of the San Andreas and Superstition Hills slip events suggest source mechanisms with seismic moments over three orders of magnitude larger than a maximum possible summation of seismic moments from all seismicity along each fault segment during the entire 4.8-year time interval spanned by the InSAR data. Aseismic moment releases of this

  16. Acoustic Instabilities Driven by Slip Between a Condensed Phase and the Gas Phase in Combustion Systems

    NASA Technical Reports Server (NTRS)

    DiCicco, M.; Buckmaster, J.

    1994-01-01

    In the context of gas turbine combustion chambers, this study describes how slip affects the response time of fuel sprays to pressure fluctuations in a gaseous flow field. Slip between the condensed and gas phases is shown to cause fuel vapor mass fraction fluctuations upstream of the reaction zone. A resulting oscillating heat release can drive the pressure fluctuations, depending on the phase difference between them. This generates an acoustic instability. With relevance to previous experimental results, differences are explored in the evaporation characteristics among three different fuel sprays (JP-4, JP-5, and D-2) in relation to their effect on the magnitude of the fuel vapor mass fraction perturbations.

  17. Earthquake hypocenters and focal mechanisms in central Oklahoma reveal a complex system of reactivated subsurface strike-slip faulting

    NASA Astrophysics Data System (ADS)

    McNamara, D. E.; Benz, H. M.; Herrmann, R. B.; Bergman, E. A.; Earle, P.; Holland, A.; Baldwin, R.; Gassner, A.

    2015-04-01

    The sharp increase in seismicity over a broad region of central Oklahoma has raised concern regarding the source of the activity and its potential hazard to local communities and energy industry infrastructure. Since early 2010, numerous organizations have deployed temporary portable seismic stations in central Oklahoma in order to record the evolving seismicity. In this study, we apply a multiple-event relocation method to produce a catalog of 3639 central Oklahoma earthquakes from late 2009 through 2014. Regional moment tensor (RMT) source parameters were determined for 195 of the largest and best recorded earthquakes. Combining RMT results with relocated seismicity enabled us to determine the length, depth, and style of faulting occurring on reactivated subsurface fault systems. Results show that the majority of earthquakes occur on near-vertical, optimally oriented (NE-SW and NW-SE), strike-slip faults in the shallow crystalline basement. These are necessary first-order observations required to assess the potential hazards of individual faults in Oklahoma.

  18. Earthquake hypocenters and focal mechanisms in central Oklahoma reveal a complex system of reactivated subsurface strike-slip faulting

    USGS Publications Warehouse

    McNamara, Daniel E.; Benz, Harley M.; Herrmann, Robert B.; Bergman, Eric A.; Earle, Paul; Holland, Austin F.; Baldwin, Randy W.; Gassner, A.

    2015-01-01

    The sharp increase in seismicity over a broad region of central Oklahoma has raised concern regarding the source of the activity and its potential hazard to local communities and energy industry infrastructure. Since early 2010, numerous organizations have deployed temporary portable seismic stations in central Oklahoma in order to record the evolving seismicity. In this study, we apply a multiple-event relocation method to produce a catalog of 3,639 central Oklahoma earthquakes from late 2009 through 2014. RMT source parameters were determined for 195 of the largest and best-recorded earthquakes. Combining RMT results with relocated seismicity enabled us to determine the length, depth and style-of-faulting occurring on reactivated subsurface fault systems. Results show that the majority of earthquakes occur on near vertical, optimally oriented (NE-SW and NW-SE), strike-slip faults in the shallow crystalline basement. These are necessary first order observations required to assess the potential hazards of individual faults in Oklahoma.

  19. Tectonic Geomorphology in the Laboratory: Evolution of landscape along an active thrust, normal and strike-slip fault

    NASA Astrophysics Data System (ADS)

    Graveleau, Fabien; Strak, Vincent; Dominguez, Stéphane; Malavieille, Jacques; Chatton, Marina; Manighetti, Isabelle; Petit, Carole

    2015-04-01

    Tectonically controlled landforms develop morphologic features that provide useful markers to investigate crustal deformation and relief growth dynamics. We present here results of morphotectonic experiments obtained with an innovative approach combining tectonic and surface processes (erosion, transport and sedimentation), coupled with accurate model monitoring techniques. This approach allows for a qualitative and quantitative analysis of landscape evolution in response to active deformation in the three end-member geological settings: compression, extension and strike-slip. Experimental results outline first that experimental morphologies evolve significantly at a short timescale. Numerous morphologic markers form continuously, but their lifetime is generally short because erosion and sedimentation processes tend to destroy or bury them. For the compressional setting, the formation of terraces above an active thrust appears mainly controlled by narrowing and incision of the main channel through the uplifting hanging-wall and by avulsion of deposits on fan-like bodies. Terrace formation is irregular even under steady tectonic rates and erosional conditions. Terrace deformation analysis allows retrieving the growth history of the structure and the fault slip rate evolution. For the extensional setting, the dynamics of hanging-wall sedimentary filling appears to control the position of the base level, which in turn controls footwall erosion. Two phases of relief evolution can be evidenced: the first is a phase of relief growth and the second is a phase of upstream propagation of topographic equilibrium that is reached first in the sedimentary basin. During the phase of relief growth, the formation of triangular facets occurs by degradation of the fault scarp and their geometry (height) becomes stationary during the phase of upstream propagation of the topographic equilibrium. For the strike-slip setting, the complex morphology of the wrench zone, composed of

  20. New constraints from seismology and geodesy on the Mw = 6.4 2008 Movri (Greece) earthquake: evidence for a growing strike-slip fault system

    NASA Astrophysics Data System (ADS)

    Serpetsidaki, A.; Elias, P.; Ilieva, M.; Bernard, P.; Briole, P.; Deschamps, A.; Lambotte, S.; Lyon-Caen, H.; Sokos, E.; Tselentis, G.-A.

    2014-09-01

    The 2008 Mw = 6.4 Movri earthquake ruptured a NNE right lateral strike-slip fault about 30 km south of the city of Patras. Although some strike-slip activity on minor faults was known, there was no tectonic evidence of large scale NS striking fault and such a large event was not anticipated. Following the event, a network of six stations was installed for 4 months in the epicentral area in order to monitor aftershocks and in particular the northern part of the rupture area closest to the city of Patras. We combine these new aftershock observations with GPS measurements of an already existing geodetic network in the area performed just after the earthquake, as well as with SAR interferograms, together with already published source studies, in order to refine already proposed models of this event. The combined data set allows defining much more accurately the lateral and vertical limits of the rupture. Its length inferred from geodesy is ˜15 km and its modelled upper edge ˜17 km. The seismic moment then constrains the lower edge to coincide, within a few kilometres, with the Moho interface. The absence of seismicity in the shallow crust above the co-seismic fault is interpreted as a result of the decoupling effect of possible presence of salt layers above the rupture area, near 14 to 16 km in depth, which favours our interpretation of an immature strike-slip fault system, compatible with the absence of surface ruptures. The immature character of this large crustal fault is further suggested by the high variability of focal mechanisms and of fault geometries deduced from aftershock clusters, in the strike direction. Its geometry and mechanism is consistent with the crustal shear, striking NNE, revealed by GPS in this region. This shear and faulting activity might be generated by the differential slip rate on the subduction interface, 50 km to the south, leading to a north-northeastward propagating strike-slip fault zone. The wide extension of the aftershock

  1. Tectonics, magmatism and fluid flow in a transtensional strike-slip setting: The northern termination of the dextral strike-slip Liquiñe-Ofqui Fault System, Chile

    NASA Astrophysics Data System (ADS)

    Perez Flores, P.; Sanchez, P.; Sielfeld, G.; Cembrano, J. M.

    2013-05-01

    One fundamental problem in continental margin tectonics is the nature of the interplay between tectonics and magma/fluid transport through the lithosphere. Deformation-driven fault-fracture networks have been regarded as efficient pathways through which magma and/or hydrothermal fluids are transported, stored and eventually connected to the earth surface. Thus, the state of stress of the lithosphere at the time of fluid transport should somehow control the first and second-order spatial distribution of dikes swarms, volcanic centers and geothermal reservoirs. We conducted a detailed structural mapping of the geometry, kinematics and relative timing of first and second-order fault systems and their spatially associated fault-vein networks at regional and local scales at the northern termination of the Liquiñe-Ofqui Fault System (LOFS). This is characterized by a transtensional imbricate fan (horsetail structure). Stratovolcanoes, minor eruptive centers, and hydrothermal vein systems are spatially and temporally associated with NNE master and ENE subsidiary faults of the LOFS and with NW-striking long-lived basement faults. The overprinted geothermal system is documented by NNE and ENE striking calcite-quartz hybrid and extensional vein systems, which appear to be associated with dextral strike-slip displacement on the LOFS. Fault-vein and vein microstructure varies from mineral fibers indicative of creeping faults to typical ridge-and-groove striae. Bladed calcite occurs in dilational jogs along the main LOFS master faults; they are interpreted to represent boiling episodes. Thicker and more pervasive NW sinistral-reverse fault-vein systems and breccias bodies suggest that the fault-valve mechanism was active during fluid transport and mineral precipitation. In some sites the NW-striking system cuts and displaces the active LOFS, suggesting that their active has extended to at least the Pleistocene.

  2. Dislocation microstructures and strain-gradient plasticity with one active slip plane

    NASA Astrophysics Data System (ADS)

    Conti, Sergio; Garroni, Adriana; Müller, Stefan

    2016-08-01

    We study dislocation networks in the plane using the vectorial phase-field model introduced by Ortiz and coworkers, in the limit of small lattice spacing. We show that, in a scaling regime where the total length of the dislocations is large, the phase field model reduces to a simpler model of the strain-gradient type. The limiting model contains a term describing the three-dimensional elastic energy and a strain-gradient term describing the energy of the geometrically necessary dislocations, characterized by the tangential gradient of the slip. The energy density appearing in the strain-gradient term is determined by the solution of a cell problem, which depends on the line tension energy of dislocations. In the case of cubic crystals with isotropic elasticity our model shows that complex microstructures may form in which dislocations with different Burgers vector and orientation react with each other to reduce the total self-energy.

  3. Slip flow in graphene nanochannels

    NASA Astrophysics Data System (ADS)

    Kannam, Sridhar Kumar; Todd, B. D.; Hansen, J. S.; Daivis, Peter J.

    2011-10-01

    We investigate the hydrodynamic boundary condition for simple nanofluidic systems such as argon and methane flowing in graphene nanochannels using equilibrium molecular dynamics simulations (EMD) in conjunction with our recently proposed method [J. S. Hansen, B. D. Todd, and P. J. Daivis, Phys. Rev. E 84, 016313 (2011), 10.1103/PhysRevE.84.016313]. We first calculate the fluid-graphene interfacial friction coefficient, from which we can predict the slip length and the average velocity of the first fluid layer close to the wall (referred to as the slip velocity). Using direct nonequilibrium molecular dynamics simulations (NEMD) we then calculate the slip length and slip velocity from the streaming velocity profiles in Poiseuille and Couette flows. The slip lengths and slip velocities from the NEMD simulations are found to be in excellent agreement with our EMD predictions. Our EMD method therefore enables one to directly calculate this intrinsic friction coefficient between fluid and solid and the slip length for a given fluid and solid, which is otherwise tedious to calculate using direct NEMD simulations at low pressure gradients or shear rates. The advantages of the EMD method over the NEMD method to calculate the slip lengths/flow rates for nanofluidic systems are discussed, and we finally examine the dynamic behaviour of slip due to an externally applied field and shear rate.

  4. Slip systems in MgSiO3 post-perovskite: implications for D'' anisotropy.

    PubMed

    Miyagi, Lowell; Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Lee, Kanani K M; Wenk, Hans-Rudolf

    2010-09-24

    Understanding deformation of mineral phases in the lowermost mantle is important for interpreting seismic anisotropy in Earth's interior. Recently, there has been considerable controversy regarding deformation-induced slip in MgSiO(3) post-perovskite. Here, we observe that (001) lattice planes are oriented at high angles to the compression direction immediately after transformation and before deformation. Upon compression from 148 gigapascals (GPa) to 185 GPa, this preferred orientation more than doubles in strength, implying slip on (001) lattice planes. This contrasts with a previous experiment that recorded preferred orientation likely generated during the phase transformation rather than deformation. If we use our results to model deformation and anisotropy development in the D'' region of the lower mantle, shear-wave splitting (characterized by fast horizontally polarized shear waves) is consistent with seismic observations. PMID:20929846

  5. Developing a Near Real-time System for Earthquake Slip Distribution Inversion

    NASA Astrophysics Data System (ADS)

    Zhao, Li; Hsieh, Ming-Che; Luo, Yan; Ji, Chen

    2016-04-01

    Advances in observational and computational seismology in the past two decades have enabled completely automatic and real-time determinations of the focal mechanisms of earthquake point sources. However, seismic radiations from moderate and large earthquakes often exhibit strong finite-source directivity effect, which is critically important for accurate ground motion estimations and earthquake damage assessments. Therefore, an effective procedure to determine earthquake rupture processes in near real-time is in high demand for hazard mitigation and risk assessment purposes. In this study, we develop an efficient waveform inversion approach for the purpose of solving for finite-fault models in 3D structure. Full slip distribution inversions are carried out based on the identified fault planes in the point-source solutions. To ensure efficiency in calculating 3D synthetics during slip distribution inversions, a database of strain Green tensors (SGT) is established for 3D structural model with realistic surface topography. The SGT database enables rapid calculations of accurate synthetic seismograms for waveform inversion on a regular desktop or even a laptop PC. We demonstrate our source inversion approach using two moderate earthquakes (Mw~6.0) in Taiwan and in mainland China. Our results show that 3D velocity model provides better waveform fitting with more spatially concentrated slip distributions. Our source inversion technique based on the SGT database is effective for semi-automatic, near real-time determinations of finite-source solutions for seismic hazard mitigation purposes.

  6. Tectonics, magmatism and paleo-fluid distribution in a strike-slip setting: Insights from the northern termination of the Liquiñe-Ofqui fault System, Chile

    NASA Astrophysics Data System (ADS)

    Pérez-Flores, Pamela; Cembrano, José; Sánchez-Alfaro, Pablo; Veloso, Eugenio; Arancibia, Gloria; Roquer, Tomás

    2016-06-01

    This study addresses the interplay between strain/stress fields and paleo-fluid migration in the Southern Andean Volcanic Zone (SVZ). The SVZ coexists with the margin-parallel Liquiñe-Ofqui Fault System (LOFS) and with NW-striking Andean Transverse Faults (ATF). To tackle the role of different fault-fracture systems on deformation distribution and magma/fluid transport, we map the nature, geometry and kinematics of faults, veins and dikes at various scales. Fault-slip data analysis yields stress and strain fields from the full study area data base (regional scale) and fault zones representative of each fault system (local scale). Regional scale strain analysis shows kinematically heterogeneous faulting. Local strain analyses indicate homogeneous deformation with NE-trending shortening and NW-trending extension at NNE-striking Liquiñe-Ofqui master fault zones. Strain axes are clockwise rotated at second order fault zones, with ENE-trending shortening and NNW-trending stretching. The ATF record polyphasic deformation. Conversely, stress field analysis at regional scale indicates a strike-slip dominated transpressional regime with N64°E-trending σ1 and N30°W-trending σ3. Deformation is further partitioned within the arc through NNE-striking dextral-reverse faults, NE-striking dextral-normal faults and NW-striking sinistral-reverse faults with normal slip activation. The regional tectonic regime controls the geometry of NE-striking dikes and volcanic centers. NE-striking faults record local stress axes that are clockwise rotated with respect to the regional stress field. NNE- and NE-striking faults are favorably oriented for reactivation under the regional stress field and show poorly-developed damage zones. Conversely, NW-striking fault systems, misoriented under the regional stress field, show multiple fault cores, wider damage zones and dense vein networks. Deformation driven by oblique subduction is partially partitioned into strike-slip and shortening

  7. Refining the shallow slip deficit

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohua; Tong, Xiaopeng; Sandwell, David T.; Milliner, Christopher W. D.; Dolan, James F.; Hollingsworth, James; Leprince, Sebastien; Ayoub, Francois

    2016-03-01

    Geodetic slip inversions for three major (Mw > 7) strike-slip earthquakes (1992 Landers, 1999 Hector Mine and 2010 El Mayor-Cucapah) show a 15-60 per cent reduction in slip near the surface (depth < 2 km) relative to the slip at deeper depths (4-6 km). This significant difference between surface coseismic slip and slip at depth has been termed the shallow slip deficit (SSD). The large magnitude of this deficit has been an enigma since it cannot be explained by shallow creep during the interseismic period or by triggered slip from nearby earthquakes. One potential explanation for the SSD is that the previous geodetic inversions lack data coverage close to surface rupture such that the shallow portions of the slip models are poorly resolved and generally underestimated. In this study, we improve the static coseismic slip inversion for these three earthquakes, especially at shallow depths, by: (1) including data capturing the near-fault deformation from optical imagery and SAR azimuth offsets; (2) refining the interferometric synthetic aperture radar processing with non-boxcar phase filtering, model-dependent range corrections, more complete phase unwrapping by SNAPHU (Statistical Non-linear Approach for Phase Unwrapping) assuming a maximum discontinuity and an on-fault correlation mask; (3) using more detailed, geologically constrained fault geometries and (4) incorporating additional campaign global positioning system (GPS) data. The refined slip models result in much smaller SSDs of 3-19 per cent. We suspect that the remaining minor SSD for these earthquakes likely reflects a combination of our elastic model's inability to fully account for near-surface deformation, which will render our estimates of shallow slip minima, and potentially small amounts of interseismic fault creep or triggered slip, which could `make up' a small percentages of the coseismic SSD during the interseismic period. Our results indicate that it is imperative that slip inversions include

  8. Southern San Andreas-San Jacinto fault system slip rates estimated from earthquake cycle models constrained by GPS and interferometric synthetic aperture radar observations

    NASA Astrophysics Data System (ADS)

    Lundgren, Paul; Hetland, Eric A.; Liu, Zhen; Fielding, Eric J.

    2009-02-01

    We use ground geodetic and interferometric synthetic aperture radar satellite observations across the southern San Andreas (SAF)-San Jacinto (SJF) fault systems to constrain their slip rates and the viscosity structure of the lower crust and upper mantle on the basis of periodic earthquake cycle, Maxwell viscoelastic, finite element models. Key questions for this system are the SAF and SJF slip rates, the slip partitioning between the two main branches of the SJF, and the dip of the SAF. The best-fitting models generally have a high-viscosity lower crust (η = 1021 Pa s) overlying a lower-viscosity upper mantle (η = 1019 Pa s). We find considerable trade-offs between the relative time into the current earthquake cycle of the San Jacinto fault and the upper mantle viscosity. With reasonable assumptions for the relative time in the earthquake cycle, the partition of slip is fairly robust at around 24-26 mm/a for the San Jacinto fault system and 16-18 mm/a for the San Andreas fault. Models for two subprofiles across the SAF-SJF systems suggest that slip may transfer from the western (Coyote Creek) branch to the eastern (Clark-Superstition hills) branch of the SJF from NW to SE. Across the entire system our best-fitting model gives slip rates of 2 ± 3, 12 ± 9, 12 ± 9, and 17 ± 3 mm/a for the Elsinore, Coyote Creek, Clark, and San Andreas faults, respectively, where the large uncertainties in the slip rates for the SJF branches reflect the large uncertainty in the slip rate partitioning within the SJF system.

  9. Traction Drives for Zero Stick-Slip Robots, and Reaction Free, Momentum Balanced Systems

    NASA Technical Reports Server (NTRS)

    Anderson, William J.; Shipitalo, William; Newman, Wyatt

    1995-01-01

    Two differential (dual input, single output) drives (a roller-gear and a pure roller), and a momentum balanced (single input, dual output) drive (pure roller ) were designed, fabricated, and tested. The differential drives are each rated at 295 rad/sec (2800 rpm) input speed, 450 N-m (4,000 in-lbf) output torque. The momentum balanced drive is rated at 302 rad/sec (2880 rpm) input speed, and dual output torques of 434N-m (3840 in-lbf). The Dual Input Differential Roller-Gear Drive (DC-700) has a planetary roller-gear system with a reduction ratio (one input driving the output with the second input fixed) of 29.23: 1. The Dual Input Differential Roller Drive (DC-500) has a planetary roller system with a reduction ratio of approximately 24:1. Each of the differential drives features dual roller-gear or roller arrangements consisting of a sun, four first row planets, four second row planets, and a ring. The Momentum Balanced (Grounded Ring) Drive (DC-400) has a planetary roller system with a reduction ratio of 24:1 with both outputs counterrotating at equal speed. Its single roller cluster consists of a sun, five first and five second row planets, a roller cage or spider and a ring. Outputs are taken from both the roller cage and the ring which counterrotate. Test results reported for all three drives include angular and torque ripple (linearity and cogging), viscous and Coulomb friction, and forward and reverse power efficiency. Of the two differential drives, the Differential Roller Drive had better linearity and less cogging than did the Differential Roller-Gear Drive, but it had higher friction and lower efficiency (particularly at low power throughput levels). Use of full preloading rather than a variable preload system in the Differential Roller Drive assessed a heavy penalty in part load efficiency. Maximum measured efficiency (ratio of power out to power in) was 95% for the Differential Roller-Gear Drive and 86% for the Differential Roller Drive. The Momentum

  10. Ascension Submarine Canyon, California - Evolution of a multi-head canyon system along a strike-slip continental margin

    USGS Publications Warehouse

    Nagel, D.K.; Mullins, H.T.; Greene, H. Gary

    1986-01-01

    Ascension Submarine Canyon, which lies along the strike-slip (transform) dominated continental margin of central California, consists of two discrete northwestern heads and six less well defined southeastern heads. These eight heads coalesce to form a single submarine canyon near the 2700 m isobath. Detailed seismic stratigraphic data correlated with 19 rock dredge hauls from the walls of the canyon system, suggest that at least one of the two northwestern heads was initially eroded during a Pliocene lowstand of sea level ???3.8 m.y. B.P. Paleogeographic reconstructions indicate that at this time, northwestern Ascension Canyon formed the distal channel of nearby Monterey Canyon and has subsequently been offset by right-lateral, strike-slip faulting along the San Gregorio fault zone. Some of the six southwestern heads of Ascension Canyon may also have been initially eroded as the distal portions of Monterey Canyon during late Pliocene-early Pleistocene sea-level lowstands (???2.8 and 1.75 m.y. B.P.) and subsequently truncated and offset to the northwest. There have also been a minimum of two canyon-cutting episodes within the past 750,000 years, after the entire Ascension Canyon system migrated to the northwest past Monterey Canyon. We attribute these late Pleistocene erosional events to relative lowstands of sea level 750,000 and 18,000 yrs B.P. The late Pleistocene and Holocene evolution of the six southeastern heads also appears to have been controlled by structural uplift of the Ascension-Monterey basement high at the southeastern terminus of the Outer Santa Cruz Basin. We believe that uplift of this basement high sufficiently oversteepened submarine slopes to induce gravitational instability and generate mass movements that resulted in the erosion of the canyon heads. Most significantly, though, our results and interpretations support previous proposals that submarine canyons along strike-slip continental margins can originate by tectonic trunction and lateral

  11. Slip reversals on active normal faults related to the inflation and deflation of magma chambers: Numerical modeling with application to the Yellowstone-Teton region

    NASA Astrophysics Data System (ADS)

    Hampel, Andrea; Hetzel, Ralf

    2008-04-01

    Earthquakes and coseismic slip on faults are the common response of Earth's crust to plate-tectonic forces. Here we demonstrate, using three-dimensional numerical experiments, that pulses of magmatic activity may alter the slip behavior of nearby tectonic faults by causing unusual aseismic creep and even reversals in the sense of slip. We apply our results to the Teton normal fault, Wyoming, which experienced hitherto unexplained episodes of reverse and normal creep between 1988 and 2001, to show that its anomalous behavior can be explained by inflation and deflation of two magma chambers beneath the Yellowstone caldera. Our findings imply a strong coupling between magmatism and tectonic faulting, which requires coordinated monitoring of both processes to improve our understanding of the resulting spatial and temporal strain pattern.

  12. Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle.

    PubMed

    Mainprice, David; Tommasi, Andréa; Couvy, Hélène; Cordier, Patrick; Frost, Daniel J

    2005-02-17

    The mineral olivine dominates the composition of the Earth's upper mantle and hence controls its mechanical behaviour and seismic anisotropy. Experiments at high temperature and moderate pressure, and extensive data on naturally deformed mantle rocks, have led to the conclusion that olivine at upper-mantle conditions deforms essentially by dislocation creep with dominant [100] slip. The resulting crystal preferred orientation has been used extensively to explain the strong seismic anisotropy observed down to 250 km depth. The rapid decrease of anisotropy below this depth has been interpreted as marking the transition from dislocation to diffusion creep in the upper mantle. But new high-pressure experiments suggest that dislocation creep also dominates in the lower part of the upper mantle, but with a different slip direction. Here we show that this high-pressure dislocation creep produces crystal preferred orientations resulting in extremely low seismic anisotropy, consistent with seismological observations below 250 km depth. These results raise new questions about the mechanical state of the lower part of the upper mantle and its coupling with layers both above and below. PMID:15716950

  13. Walker Lake, Nevada: sedimentation in an active, strike-slip related basin

    SciTech Connect

    Link, M.H.; Roberts, M.T.

    1984-04-01

    Walker Lake, Nevada, is in an active fault-controlled basin related to the right-lateral, northwest-trending Walker Lane Shear Zone on the western side of the Basin and Range province. The lake occurs in a half graben bounded on its west side by a high-angle normal fault zone along the Wassuk Range front. This fault zone may merge to the north into the Walker Lane fault system, which forms the northeast boundary of the basin. To the south of Walker Lake, the Wassuk front fault merges with an east-northeast trending left-lateral fault. The Walker Lake basin is interpreted to be a pull-apart basin formed within the triangular zone bounded by the Wassuk front, the Walker Lane, and left-lateral faults. The Walker River drainage basin occupies about 10,000 km/sup 2/ (3800 mi/sup 2/) in western Nevada and parts of California and is essentially a closed hydrologic system that drains from the crest of the Sierra Nevada in California and terminates in Walker Lake. Walker Lake trends north-northwest and is 27.4 km (17 mi) long and 8 km (5 mi) wide with water depths exceeding 30 m (100 ft). Lake Lahontan (Wisconsinian) shorelines ring Walker Lake and suggest water depths of 150 m (500 ft) above the present lake level. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and gentle, areally more extensive fans flanking the eastern shoreline (Gillis Range). The Walker River delta enters the lake from the north and is a major sediment point source for the basin. Older dissected shoreline, alluvial fan, Gilbert delta, and beach ridge deposits were built largely of coarse-grained, locally derived materials. Stromatolites, oncolites, and tufas formed along the shorelines, whereas mud and organic sediments accumulated in the lake on the west side of the basin. Extensive submerged sand flats and local sand dunes occur on the east side of the basin.

  14. Strike-slip linked core complexes: A new kinematic model of basement rock exhumation in a crustal-scale fault system

    NASA Astrophysics Data System (ADS)

    Meyer, Sven Erik; Passchier, Cees; Abu-Alam, Tamer; Stüwe, Kurt

    2014-05-01

    Metamorphic core complexes usually develop as extensional features during continental crustal thinning, such as the Basin and Range and the Aegean Terrane. The Najd fault system in Saudi Arabia is a 2000 km-long and 400 km-wide complex network of crustal-scale strike-slip shear zones in a Neoproterozoic collision zone. Locally, the anastomosing shear zones lead to exhumation of lower crustal segments and represent a new kinematic model for the development of core complexes. We report on two such structures: the Qazaz complex in Saudi Arabia and the Hafafit complex in Egypt. The 15 km-wide Qazaz complex is a triangular dome of gently dipping mylonitic foliations within the 140 km-long sinistral strike-slip Qazaz mylonite zone. The gneissic dome consists of high-grade rocks, surrounded by low-grade metasediments and metavolcanics. The main SE-trending strike-slip Qazaz shear zone splits southwards into two branches around the gneiss dome: the western branch is continuous with the shallow dipping mylonites of the dome core, without overprinting, and changes by more than 90 degrees from a NS-trending strike-slip zone to an EW-trending 40 degree south-dipping detachment that bounds the gneiss dome to the south. The eastern SE-trending sinistral strike-slip shear zone branch is slightly younger and transects the central dome fabrics. The gneiss dome appears to have formed along a jog in the strike-slip shear zone during 40 km of horizontal strike-slip motion, which caused local exhumation of lower crustal rocks by 25 km along the detachment. The eastern shear zone branch formed later during exhumation, transacted the gneiss dome and offset the two parts by another 70 km. The Hafafit core complex in Egypt is of similar shape and size to the Qazaz structure, but forms the northern termination of a sinistral strike-slip zone that is at least 100 km in length. This zone may continue into Saudi Arabia as the Ajjaj shear zone for another 100 km. The NW trending strike slip

  15. The Friction Evolution of Siliceous Rocks during High-Velocity Slip By Thermal Activated Transition from Powder Lubrication and Rolling to Gouge Melting

    NASA Astrophysics Data System (ADS)

    Chen, X.; Madden, A. S.; Reches, Z.

    2014-12-01

    thermally activated stage (high velocity, high normal stress, long slip-distance) that leads to weakening by viscous flow. Further, the energy dissipation associated with partial-melting explains the unexpected strengthening for granite faults slipping at velocities of 0.05-0.2 m/s (Fig. 1b).

  16. Liquid slip on a nanostructured surface.

    PubMed

    Lee, Doo Jin; Cho, Ki Yeon; Jang, Soohwan; Song, Young Seok; Youn, Jae Ryoun

    2012-07-17

    We explored a liquid slip, referred to as the Navier slip, at liquid-solid interface. Such a slip is provoked by the physicochemical features of the liquid-solid system. The goal of this study was to investigate the effect of a nanoengineered surface structure on liquid slip by fabricating the self-assembly structure of nano Zinc oxide (n-ZnO). We have also examined how the liquid-solid surface interaction controlled by hydrophobic chemical treatment affects the liquid slip. The findings showed that liquid slip increases with decreasing the characteristic length scales (e.g., channel height and depth), resulting in drag reduction. It was also found that dewetted (Cassie) state due to the generation of air gap developed by n-ZnO was more critical for the liquid slip than the minimization of interface interaction. The linear and nonlinear Navier slip models showed that liquid slip behavior is more obvious when increasing the nonlinearity. This study will contribute to understanding of the underlying physics behind fluid slip phenomena, such as the Navier slip for Newtonian liquids and Maxwell's slip for Newtonian gases. PMID:22717057

  17. Microstructural and Rheological Constraints on the Mantle Strength of Strike-Slip Fault Systems: Evidence from the Bogota Peninsula Shear Zone, New Caledonia

    NASA Astrophysics Data System (ADS)

    Chatzaras, V.; Titus, S.; Tikoff, B.; Drury, M. R.

    2014-12-01

    Crust-mantle coupling along major strike-slip fault zones suggests that these two lithospheric layers act as an integrated system. In such a system, the spatial and temporal evolution of mantle strength across strike-slip shear zones has proven a key component in understanding lithospheric deformation and rheology. The Bogota Peninsula shear zone is exposed in the mantle section of the New Caledonia ophiolite. It contains a unique microstructural and textural record across a 4-km wide mylonitic zone bordered by a wider zone of weaker deformation. The shear zone is interpreted as a paleotransform fault, based on the orientations of fabrics and dikes inside and outside the zone. No ultramylonites or pseudotachylites were observed within the shear zone. Olivine grain size paleopiezometers suggest variation of the shear zone stresses, with the highest values recorded in the center of the shear zone, coincident with increasing olivine CPO strength toward the shear zone center. By estimating the finite strain in the zone, and assuming that all portions of the shear zone were active synchronously, we can correlate the increased stresses to increased strain rates. We compare the mantle strength in the Bogota Peninsula shear zone to other transform faults, such as the San Andreas fault (SAF) system. The differential stresses in the upper mantle of the SAF system, determined from xenoliths, is similar to those observed in the New Caledonia. Further, the width of shearing deformation in Bogota Peninsula shear zone is similar to that inferred for other transform zones, in both the upper crust and lithospheric mantle. These similarities suggest that viscous flow in the lithospheric mantle is in mechanical communication to brittle deformation in the upper crust. We propose a "Lithospheric Feedback" model, in which displacement due to mantle flow loads the crust during interseismic cycles, while the upper crust effectively limits the strength of the lithosphere.

  18. New evidence for active deformation off the Annaba region (easternmost Algerian margin): Estimates of Quaternary shortening and slip rates from folding analyses

    NASA Astrophysics Data System (ADS)

    Kherroubi, A.; Deverchere, J.; Yelles, A.; Mercier de Lepinay, B.; Domzig, A.; Graindorge, D.; Bracene, R.; Cattaneo, A.; Gaullier, V.

    2007-12-01

    From the first marine investigations off the region of Annaba (easternmost part of Algeria) made after the MARADJA2 survey in November 2005, a set of large active faults and folds was discovered near the foot of the margin. This active thrust system resumes a previous passive margin and creates growth strata deposition on the backlimbs of large Quaternary folds, resulting in the development of perched basins at the foot of the margin since less than 1 Ma. The system forms a set of overlapping fault segments verging towards the Algerian basin. From the seismic line analysis (high-resolution and Chirp data), and using sedimentation rates obtained from coring and extrapolated, a shortening rate of about 0.9 mm/yr is estimated. If we consider a single fault dipping at about 45° (hypothesized from the Boumerdès 2003 rupture zone), a fault slip rate of about 1.3 mm/yr can be postulated. Considering recent kinematic studies, this fault-related fold system could accommodate a significant part of the present-day submarine shortening rate between the European and African plates, predicted by Stich et al. (2006) to be 1.5 mm/yr from GPS modelling. This faulting is apparently active at a faster rate than the similar faulting observed at the foot of the margin NW of Algiers. This system of faults off Annaba represents a major threat for the region. Indeed, the location of this system changes drastically the seismic hazard assessment of the region, since no large historical earthquake is reported there since 3 centuries at least.

  19. The 1994 Sefidabeh earthquakes in eastern Iran: blind thrusting and bedding-plane slip on a growing anticline, and active tectonics of the Sistan suture zone

    NASA Astrophysics Data System (ADS)

    Berberian, M.; Jackson, J. A.; Qorashi, M.; Talebian, M.; Khatib, M.; Priestley, K.

    2000-08-01

    In 1994 a sequence of five earthquakes with Mw 5.5-6.2 occurred in the Sistan belt of eastern Iran, all of them involving motion on blind thrusts with centroid depths of 5-10km. Coseismic ruptures at the surface involved bedding-plane slip on a growing hanging-wall anticline displaying geomorphological evidence of uplift and lateral propagation. The 1994 earthquakes were associated with a NW-trending thrust system that splays off the northern termination of a major N-S right-lateral strike-slip fault. Elevation changes along the anticline ridge suggest that displacement on the underlying thrust dies out to the NW, away from its intersection with the strike-slip fault. This is a common fault configuration in eastern Iran and accommodates oblique NE-SW shortening across the N-S deforming zone, probably by anticlockwise rotations about a vertical axis. This style of fault kinematics may be transitional to a more evolved state that involves partitioning of the strike-slip and convergent motion onto separate subparallel faults.

  20. Episodic tremor and slip on the Cascadia subduction zone: the chatter of silent slip.

    PubMed

    Rogers, Garry; Dragert, Herb

    2003-06-20

    We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor activity is minor or nonexistent. We call this associated tremor and slip phenomenon episodic tremor and slip (ETS) and propose that ETS activity can be used as a real-time indicator of stress loading of the Cascadia megathrust earthquake zone. PMID:12738870

  1. Slipped and lost extraocular muscles.

    PubMed

    Lenart, T D; Lambert, S R

    2001-09-01

    A slipped or lost muscle should be considered in the differential diagnosis of a patient presenting with a marked limitation of duction and inability to rotate the eye beyond the midline. Loss of a rectus muscle can occur after strabismus surgery, trauma, paranasal sinus surgery, orbital surgery, or retinal detachment surgery. The extraocular rectus muscle most frequently slipped or lost is the medial rectus muscle. Forced ductions, active force generation, saccadic velocity studies, differential intraocular pressure measurements, and orbital imaging studies may aid in identifying a slipped or lost muscle. However, no single diagnostic test provides absolute reliability for determining a lost muscle. Slipped muscles develop when the muscular capsule is imbricated without including the muscle or muscle tendon during strabismus surgery. When the capsule is reattached to the sclera, the tendon and muscle are then free to slip posteriorally from the site of attachment. Slipped muscles are retrieved by following the thin avascular muscle capsule posteriorally until the muscle is identified. A lost muscle can be found using a traditional conjunctival approach, by an external orbitotomy, or by an endoscopic transnasal approach. Although many diagnostic maneuvers are useful in identifying a lost rectus muscle, the oculocardiac reflex is the most important. Once the lost muscle is identified, the muscle should be imbricated with a nonabsorbable synthetic suture and securely reattached to the globe. PMID:11705143

  2. Stress fields recorded on large-scale strike-slip fault systems: Effects on the tectonic evolution of crustal slivers during oblique subduction

    NASA Astrophysics Data System (ADS)

    Veloso, Eugenio E.; Gomila, Rodrigo; Cembrano, José; González, Rodrigo; Jensen, Erik; Arancibia, Gloria

    2015-11-01

    In continental margins, large-scale, strike-slip fault-systems resulted from oblique subduction commonly exhibit a complex pattern of faulting where major faults define the inland boundary of tectonic slivers that can be detached from the margin. In turn, subsidiary faults bound and define internal tectonic blocks within the sliver which are expected to rotate, translate and/or internally disrupt in order to accommodate the internal deformation. The geometrical and spatial arrangement of faults and tectonic blocks thus determines the evolution of the sliver given a particular stress field regime. The Paposo segment of the Atacama Fault System in northern Chile displays a series of brittle faults whose orientations are hierarchically arranged: low-order faults splay off higher-order faults forming Riedel-type and strike-slip duplexes geometries at several scales. The master (1st- and highest-order) Paposo Fault defines the inland boundary of a tectonic sliver whereas subsidiary faults bound and disrupt internal tectonic blocks. By using newly collected brittle fault-slip data we estimated the orientations and regimes of the stress fields that acted upon the entire sliver, the different fault-orders and the tectonic blocks. Results indicate that an overall transtensional - with NW-compressional and NE-tensional principal axes - strike-slip regime affected the sliver and triggered the development of left-lateral strike-slip structures. An incomplete split of the stress field imposed by the subduction process resulted in the generation of a nested pattern of R-type faults as well as in a combined strike-slip/normal faulting disruption of the tectonic blocks within the sliver.

  3. Late Quaternary Activity and Seismogenic Potential of the Gonave Microplate: Plantain Garden Strike-Slip Fault Zone of Eastern Jamaica

    NASA Astrophysics Data System (ADS)

    Mann, P.; Prentice, C.; King, W.; Demets, C.; Wiggins-Grandison, M.; Benford, B.

    2008-12-01

    At the longitude of Jamaica, Caribbean (Carib)-North America (Noam) plate motion of 19 ± 2 mm/a is carried by two parallel, left-lateral strike-slip faults, the Oriente fault zone, immediately south of Cuba, and the Enriquillo-Plantain Garden fault zone (EPGFZ), which lies 100-150 km further south. It has been postulated that the lithosphere between these faults constitutes an independent Gonave microplate that has formed in response to the ongoing collision between the leading edge of Carib in Hispaniola and the Bahama carbonate platform. GPS measurements in Jamaica and Hispanola is supportive of the microplate hypothesis and indicates that roughly half of Carib-Noam plate motion (8-14 mm/a) is carried by the EPGFZ of southern Hispaniola and eastern Jamaica. This study applies geomorphic and paleoseismic methods as a direct test of the activity and amount of microplate motion carried on the Plantain Garden fault segment of eastern Hispaniola and how this motion is distributed across a large restraining bend that has formed the island of Jamaica since the late Miocene. The EPFZ curves gently to the northeast and forming a steep mountain front to the Blue Mountains restraining bend with elevations up to 2200 m. Geomorphic fault-related features along the mountain front fault zone include left-laterally deflected rivers and streams, but no small scale features indicative of Holocene activity. River and stream deflections range from 0.1 to 0.5 km. We identified and trenched the most active trace of the mountain front fault at the Morant River where the fault is characterized by a 1.5-m-wide sub-vertical fault zone juxtaposing sheared alluvium and fault Cretaceous basement rocks This section is overlain by a 6-m-thick fluvial terrace. Trenching in the unfaulted terrace immediately overlying the fault trace revealed radiocarbon and OSL ages ranging from 20 to 21 ka that are consistent with a prominent unfaulted alluvial fan along the projection of this fault 1.5 km to

  4. Ground Motion Polarization in the Damage Zone of the Active, Strike-Slip Mattinata Fault, Southern Italy

    NASA Astrophysics Data System (ADS)

    Pischiutta, M.; Cianfarra, P.; Anselmi, M.; Salvini, F.; Rovelli, A.

    2013-12-01

    We have recently observed the occurrence of directional amplification effects in fault zones using both earthquakes and ambient noise records. In several faults we have found that ground motion polarization tends to have a high angle to cleavages produced by the stress related to the kinematics in the fault damage zone. We thus interpret this effect as due to the higher compliance of the fractured rocks of the damage zone in a direction transversal to the cleavage strike. Here we have tested the technique of the wavefield polarization using ambient vibrations recorded across the seismically active Mattinata Fault, in the Gargano Promontory, Italy. This fault has been chosen for the high number of structural investigations led out so far. The Mattinata Fault outcrops for over 40 km and shows an ondulated trajectory that is characterized by a number of significant tectonic-related morphological features compatible with a general left-lateral strike-slip kinematics. These features include a pull-apart basin and a transpressional zone. The main associated cleavage consists of a marked array of disjunctive, spaced pressure-solution surfaces developed within the 200-300 m wide fault damage zone. In order to relate the orientation of cleavage to the ground motion polarization, we measured 20-50 min of ambient noise at about 30 sites chosen in the fault damage zone close to rock outcrops where also structural geological measurements were carried out. Ground motion polarization is assessed both in the frequency and time domain through the individual-station horizontal-to-vertical spectral ratio and covariance-matrix analysis, respectively. Two ambient noise measurements were performed close to permanent broadband stations of the Italian Seismic Telemetric Network. Results are consistent with those inferred on earthquake records at the two permanent stations, confirming that ambient noise yields results consistent with earthquake records as previously observed in other

  5. Fault zone development and strain partitioning in an extensional strike-slip duplex: A case study from the Mesozoic Atacama fault system, Northern Chile

    NASA Astrophysics Data System (ADS)

    Cembrano, J.; González, G.; Arancibia, G.; Ahumada, I.; Olivares, V.; Herrera, V.

    2005-05-01

    Upper crustal strike-slip duplexes provide an excellent opportunity to address the fundamental question of fault zone development and strain partitioning in an evolving system. Detailed field mapping of the Mesozoic Atacama fault system in the Coastal Cordillera of Northern Chile documents the progressive development of second- and third-order faults forming a duplex at a dilational jog between two overstepping master faults: the sinistral strike-slip, NNW-striking, Jorgillo and Bolfin faults. These are constituted by a meter-wide core of foliated S-C ultracataclasite and cataclasite, flanked by a damage zone of protocataclasite, splay faults and veins. Lateral separation of markers along master faults is on the order of a few kilometers. Second-order, NW-striking, oblique-slip subsidiary fault zones do not show foliated ultracataclasite; lateral sinistral separations are in the range of ˜ 10 to 200 m with a relatively minor normal dip-slip component. In turn, third-order, east-west striking normal faults exhibit centimetric displacement. Oblique-slip (sinistral-normal) fault zones located at the southern termination of the Bolfin fault form a well-developed imbricate fan structure. They exhibit a relatively simple architecture of extensional and extensional-shear fractures bound by low displacement shear fractures. Kinematic analysis of fault slip data from mesoscopic faults within the duplex area, document that the NW-striking and the EW-striking faults accommodate transtension and extension, respectively. Examination of master and subsidiary faults of the duplex indicates a strong correlation between total displacement and internal fault structure. Faults started from arrays of en echelon extensional/extensional-shear fractures that then coalesced into throughgoing strike-slip faults. Further displacement leads to the formation of discrete bands of cataclasite and ultracataclasite that take up a significant part of the total displacement. We interpret that the

  6. Slipped capital femoral epiphysis

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/000972.htm Slipped capital femoral epiphysis To use the sharing features on this page, please enable JavaScript. A slipped capital femoral epiphysis is a separation of the ball ...

  7. Late quaternary active characteristics and slip-rate of Pingding-Huama Fault, the eastern segment of Guanggaishan-Dieshan Fault zone ( West Qinlin Mountain )

    NASA Astrophysics Data System (ADS)

    Jingxing, Y.; Wenjun, Z.; Daoyang, Y.; Jianzhang, P.; Xingwang, L.; Baiyun, L.

    2012-12-01

    Stretching along the west QinlinShan in the north Tibet, the Guanggaishan-Dieshanfaultis composed of three sub-parallel faults among which the major one is a fault named Pingding-Huama fault. The Pingding-Huama fault can be further defined as a combination of a western segment and an eastern segment separated by Minjiang river at Dangchang. Along the western segment of the Pingding-Huama fault, significant linear characteristics, scars, and fault scarps cutting several alluvial fans can be easily distinguished, indicating that the western segment is active since the late Quatenary and the elapsed time of the last event should be less than 1ka B.P.. We estimated the slip rates of the western segment through geomorphology analysis and dating the age of the top surface of terraces and the deformed strata (OSL, 14C). The results show that its reverse slip rate ranges from 0.69±0.16 to 1.15±0.28mm/a and the sinistral slip rate is 0.51±0.13mm/a. In contrast to the simple structure of the western segment, the eastern segment consists of several sub-parallel faults as well as oblique intersected faults. On all faults of the eastern segment, no sign of recent movement was discovered. Along these faults, the tectonic topography features a sequence of linear valleys in the west and dominant folds in the east. Only striations in bedrock and geomorphology show that the eastern segment was reversely slipping on the whole with sinistral component. In summary, at present the Pingding-Huama fault is active along its western segment while shows very weak deformation along the eastern segment.

  8. Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Hartwell, Stephen R.; Dartnell, Peter

    2014-01-01

    The Hosgri fault is the southern part of the regional Hosgri–San Gregorio dextral strike‐slip fault system, which extends primarily in the offshore for about 400 km in central California. Between Morro Bay and San Simeon, high‐resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by an ∼265  m wide slope interpreted as the shoreface of a latest Pleistocene sand spit. This sand spit crossed an embayment and connected a western fault‐bounded bedrock peninsula and an eastern bedrock highland, a paleogeography resembling modern coastal geomorphology along the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6±0.9  mm/yr, considered a minimum rate for the Hosgri given the presence of an active western strand. This slip rate indicates that the Hosgri system takes up the largest share of the strike‐slip fault budget and is the most active strike‐slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high‐resolution bathymetry in characterization of active offshore faults.

  9. 'Extra-regional' strike-slip fault systems in Chile and Alaska: the North Pacific Rim orogenic Stream vs. Beck's Buttress

    NASA Astrophysics Data System (ADS)

    Redfield, T. F.; Scholl, D. W.; Fitzgerald, P. G.

    2010-12-01

    The ~2000 km long Denali Fault System (DFS) of Alaska is an example of an extra-regional strike-slip fault system that terminates in a zone of widely-distributed deformation. The ~1200 km long Liquiñe-Ofqui Fault Zone (LOFZ) of Patagonia (southern Chile) is another. Both systems are active, having undergone large-magnitude seismic rupture is 2002 (DFS) and 2007 (LOFZ). Both systems appear to be long-lived: the DFS juxtaposes terranes that docked in at least early Tertiary time, whilst the central LOFZ appears to also record early Tertiary or Mesozoic deformation. Both fault systems comprise a relatively well-defined central zone where individual fault traces can be identified from topographic features or zones of deformed rock. In both cases the proximal and distal traces are much more diffuse tributary and distributary systems of individual, branching fault traces. However, since their inception the DFS and LOFZ have followed very different evolutionary paths. Copious Alaskan paleomagnetic data are consistent with vertical axis small block rotation, long-distance latitudinal translation, and a recently-postulated tectonic extrusion towards a distributary of subordinate faults that branch outward towards the Aleution subduction zone (the North Pacific Rim orogenic Stream; see Redfield et al., 2007). Paleomagnetic data from the LOFZ region are consistent with small block rotation but preclude statistically-significant latitudinal transport. Limited field data from the southernmost LOFZ suggest that high-angle normal and reverse faults dominate over oblique to strike-slip structures. Rather than the high-angle oblique 'slivering regime' of the southeasternmost DFS, the initiation of the LOFZ appears to occur across a 50 to 100 km wide zone of brittly-deformed granitic and gneissic rock characterized by bulk compression and vertical pathways of exhumation. In both cases, relative plate motions are consistent with the hypothetical style, and degree, of offset, leading

  10. Thermochronologic constraints on the Miocene slip history of the South Tibetan detachment system in the Everest region, central Himalaya

    NASA Astrophysics Data System (ADS)

    Schultz, M.; Hodges, K. V.; Van Soest, M. C.; Wartho, J. A.

    2014-12-01

    North-dipping, low-angle normal faults of the South Tibetan detachment system (STDS) can be traced for a distance of more than 2000 km along strike and represent an important tectonic characteristic of the Miocene Himalayan-Tibetan orogenic system. Nowhere is the STDS better exposed than the N-S-trending Rongbuk Valley in southern Tibet, where it can be traced down dip from the summit of Everest for a distance of over 30 km before disappearing beneath the valley floor. This places a minimum constraint on Miocene displacement on the feature in this area, but some research groups have suggested ~200 km of displacement based on the difference in metamorphic pressures across the STDS and the very low (< 15˚) primary dip of the structure. We are exploring this issue further using developing (U-Th)/He and 40Ar/39Ar datasets from deformed footwall sillimanite gneisses and leucogranites. Data obtained thus far indicate relatively rapid cooling of the footwall after the intrusion of deformed leucogranites at ca. 16.7 Ma to muscovite 40Ar/39Ar closure temperatures (ca. 15.5-14.2 Ma) and zircon (U-Th)/He closure temperatures (ca. 14.5-11 Ma). We attribute this cooling to tectonic denudation related to ca. 16 Ma STDS slip. Although the (U-Th)/He systematics of apatites from these rocks is complex, our current interpretation of available data places cooling through the ca. 75˚C closure isotherm at ca. 8-9 Ma, which would suggest a significant reduction in cooling rate that is observed in our inverse model runs of the 1D program, HeFTy. Ongoing analyses of footwall samples from ~8 km to the north of our Rongbuk sample localities in the Ra Chu river valley will greatly strengthen our datasets. With the Ra Chu analyses, our datasets will constrain the cooling history of the footwall for more than 20 km perpendicular to the strike of the detachment. Our presentation will also incorporate results from the program Pecube that will contribute to our calculation of the slip rate by

  11. An investigation of active subglacial thrust glaciotectonics and its role in stick-slip motion from Skalafellsjokull, Iceland

    NASA Astrophysics Data System (ADS)

    Hart, J. K.; Rose, K. C.; Edwards, L.; Clayton, A.; Martinez, K.

    2012-12-01

    Glacier basal movement is by sliding, sediment shearing, or sediment shearing at depth. This movement can either be constant, or discontinuous via stick-slip motion. This is controlled by the interrelationship between pore water pressure and till rheology. There have been very few modern observations of subglacial shearing at depth, although glaciotectonic thrust sheets have been commonly reported from Quaternary and modern glacier forelands. Skalafellsjökull, Iceland represents a rare opportunity to study this style of basal movement. Ground penetrating radar (GPR) studies made in 2008 and 2011 showed that thrust slices of till were present beneath the glacier, and the amount of movement of these slices could be measured. Sediments exposed in the foreland also demonstrated that thin slices of till had been glaciotectonically deformed. We use this data combined with a 2 year record from the Glacsweb subglacial wireless probe, and passive seismics to investigate the relationship between subglacial shearing at depth and stick-slip motion.

  12. Detecting young, slow-slipping active faults by geologic and multidisciplinary high-resolution geophysical investigations: A case study from the Apennine seismic belt, Italy

    NASA Astrophysics Data System (ADS)

    Improta, L.; Ferranti, L.; de Martini, P. M.; Piscitelli, S.; Bruno, P. P.; Burrato, P.; Civico, R.; Giocoli, A.; Iorio, M.; D'Addezio, G.; Maschio, L.

    2010-11-01

    The Southern Apennines range of Italy presents significant challenges for active fault detection due to the complex structural setting inherited from previous contractional tectonics, coupled to very recent (Middle Pleistocene) onset and slow slip rates of active normal faults. As shown by the Irpinia Fault, source of a M6.9 earthquake in 1980, major faults might have small cumulative deformation and subtle geomorphic expression. A multidisciplinary study including morphological-tectonic, paleoseismological, and geophysical investigations has been carried out across the extensional Monte Aquila Fault, a poorly known structure that, similarly to the Irpinia Fault, runs across a ridge and is weakly expressed at the surface by small scarps/warps. The joint application of shallow reflection profiling, seismic and electrical resistivity tomography, and physical logging of cored sediments has proved crucial for proper fault detection because performance of each technique was markedly different and very dependent on local geologic conditions. Geophysical data clearly (1) image a fault zone beneath suspected warps, (2) constrain the cumulative vertical slip to only 25-30 m, (3) delineate colluvial packages suggesting coseismic surface faulting episodes. Paleoseismological investigations document at least three deformation events during the very Late Pleistocene (<20 ka) and Holocene. The clue to surface-rupturing episodes, together with the fault dimension inferred by geological mapping and microseismicity distribution, suggest a seismogenic potential of M6.3. Our study provides the second documentation of a major active fault in southern Italy that, as the Irpinia Fault, does not bound a large intermontane basin, but it is nested within the mountain range, weakly modifying the landscape. This demonstrates that standard geomorphological approaches are insufficient to define a proper framework of active faults in this region. More in general, our applications have wide

  13. The stress shadow effect: a mechanical analysis of the evenly-spaced parallel strike-slip faults in the San Andreas fault system

    NASA Astrophysics Data System (ADS)

    Zuza, A. V.; Yin, A.; Lin, J. C.

    2015-12-01

    Parallel evenly-spaced strike-slip faults are prominent in the southern San Andreas fault system, as well as other settings along plate boundaries (e.g., the Alpine fault) and within continental interiors (e.g., the North Anatolian, central Asian, and northern Tibetan faults). In southern California, the parallel San Jacinto, Elsinore, Rose Canyon, and San Clemente faults to the west of the San Andreas are regularly spaced at ~40 km. In the Eastern California Shear Zone, east of the San Andreas, faults are spaced at ~15 km. These characteristic spacings provide unique mechanical constraints on how the faults interact. Despite the common occurrence of parallel strike-slip faults, the fundamental questions of how and why these fault systems form remain unanswered. We address this issue by using the stress shadow concept of Lachenbruch (1961)—developed to explain extensional joints by using the stress-free condition on the crack surface—to present a mechanical analysis of the formation of parallel strike-slip faults that relates fault spacing and brittle-crust thickness to fault strength, crustal strength, and the crustal stress state. We discuss three independent models: (1) a fracture mechanics model, (2) an empirical stress-rise function model embedded in a plastic medium, and (3) an elastic-plate model. The assumptions and predictions of these models are quantitatively tested using scaled analogue sandbox experiments that show that strike-slip fault spacing is linearly related to the brittle-crust thickness. We derive constraints on the mechanical properties of the southern San Andreas strike-slip faults and fault-bounded crust (e.g., local fault strength and crustal/regional stress) given the observed fault spacing and brittle-crust thickness, which is obtained by defining the base of the seismogenic zone with high-resolution earthquake data. Our models allow direct comparison of the parallel faults in the southern San Andreas system with other similar strike-slip

  14. Behavior of aircraft antiskid braking systems on dry and wet runway surfaces. A slip-velocity-controlled, pressure-bias-modulated system

    NASA Technical Reports Server (NTRS)

    Stubbs, S. M.; Tanner, J. A.; Smith, E. G.

    1979-01-01

    The braking and cornering response of a slip velocity controlled, pressure bias modulated aircraft antiskid braking system is investigated. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC 9 series 10 airplane. The landing gear strut was replaced by a dynamometer. The parameters, which were varied, included the carriage speed, tire loading, yaw angle, tire tread condition, brake system operating pressure, and runway wetness conditions. The effects of each of these parameters on the behavior of the skid control system is presented. Comparisons between data obtained with the skid control system and data obtained from single cycle braking tests without antiskid protection are examined.

  15. Active Strike-Slip Faulting in the Inner Continental Borderland, Southern California: Results From New High-Resolution Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Conrad, J. E.; Ryan, H. F.; Sliter, R. W.

    2008-12-01

    The inner Continental Borderland offshore of southern California accommodates about 7 mm/yr of slip between the North American and Pacific plates. Nearly half of this total has previously been thought to be taken up on the Palos Verdes (PV) and Coronado Bank (CB) fault zones, which have been modeled as a single, continuous fault zone in recent seismic hazard assessments for southern California. Although these faults lie roughly on strike with each other, a connection between these faults has not been clearly demonstrated. Newly acquired high-resolution seismic reflection data indicate that the PV fault terminates southwest of Lasuen Knoll in a horsetail splay that becomes progressively buried to the south. The lack of a connection between the PV and CB fault zones implies that a significant amount of slip must be taken up elsewhere in the inner Continental Borderland. Two other significant offshore faults, the San Diego Trough (SDT) and San Pedro Basin (SPB) fault zones, lie about 10-15 km southwest of and sub parallel to the trace of the PV and CB faults. The SDT fault zone extends from south of the Mexican border near Punta Santo Tomas for about 150 km northward to near Crespi Knoll. The SPB fault zone extends northward from off Santa Catalina Island to near Point Dume. The new seismic reflection data reveal a previously unmapped but apparently active fault zone along strike and in the area between the known strands of the SDT and the SPB fault zones. This newly recognized fault links the SDT and SPB faults, forming a continuous, active fault zone that extends about 250 km along the inner Continental Borderland. Although there are no slip rate data available for this fault zone, its overall length, continuity, and active character suggest that a significant portion of the plate motion that occurs offshore is accommodated along the SDT-SPB fault zone, which may pose a more significant seismic hazard than previously recognized.

  16. Offset of Latest Pleistocene Shoreface Reveals Slip Rate on the Hosgri Strike-Slip Fault, Offshore Central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Hartwell, S. R.; Dartnell, P.

    2014-12-01

    The Hosgri fault is the southern part of the regional Hosgri-San Gregorio dextral strike-slip fault system, which extends primarily in the offshore region for about 400 km in central California. Between Morro Bay and San Simeon, high-resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by a ~265-m-wide slope interpreted as the shoreface of a relict sand spit that formed during a period of relatively slower sea-level rise (Younger Dryas stadial) in the latest Pleistocene. This sand spit crossed an embayment and connected a western fault-bounded bedrock peninsula and an eastern bedrock highland, a paleogeography similar to modern geomorphology along coastal segments of the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6 ± 0.9 mm/yr. Because the Hosgri fault locally includes an active western strand, and regionally converges with several other faults, this slip rate should be considered a minimum for the Hosgri fault in central California and should not be applied for the entire Hosgri-San Gregorio fault system. This slip rate indicates that the Hosgri system takes up the largest share of the strike-slip fault budget and is the most active strike-slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high-resolution bathymetry in earthquake-hazard characterization of active offshore faults.

  17. Holocene slip rates along the San Andreas Fault System in the San Gorgonio Pass and implications for large earthquakes in southern California.

    NASA Astrophysics Data System (ADS)

    Heermance, R. V., III; Yule, D.

    2015-12-01

    Since the late 17th century the San Andreas Fault (SAF) in southern California has produced three large (M7.3-7.8) earthquakes that did not break through San Gorgonio Pass (SGP). This pass-as-a-barrier behavior can be explained by the complexity of the SAF system. Here the fault splays and rotates into a series of en-echelon, oblique-dextral thrusts. In the center of SGP two sub-parallel thrusts are 1.5 km apart (the northern (NF) and southern (SF) splays), and form well-preserved fault scarps (up to 15 m high) in at least 3 alluvial fan terraces formed on the Millard Canyon fan. New, 10Be cosmogenic depth profiles and boulder exposure ages constrain the ages of the two oldest Holocene fan surfaces (Qt4, Qt3) to 8900 (range: 7300-11600) and 8300 (range: 6800-10300) y.b.p.. Radiocarbon ages constrain the younger surface (Qt2) at ~1500 y.b.p.. Qt4 contains a 10.5-15.1 m high scarp along the SF and has an uplift rate of 0.9-2.1 mm/yr. Qt3 is inset 1.5 m within Qt4, and contains a 3.6-6.2 m high scarp on the SF and 2.9-5.3 m high scarp on the NF with 0.4-0.9 mm/yr and 0.3-0.8 mm/yr uplift rates, respectively. Qt2 is inset ~4 m within Qt3, and contains a 1.0-2.9 m high scarp on the NF with a 0.9-2.4 mm/yr uplift rate. Using measured fault dips of 45 (NF) and 20-30 (SF) degrees combined with a slip vector inferred from regional GPS data and 2:1 lateral to thrust offset markers, we calculate the net oblique slip rate on these faults at Millard Canyon at 2.1-4.8 mm/yr for Qt4 and 1.0-2.7 mm/yr for Qt3 (SF), and 0.8-2.2 mm/yr for Qt3 and 1.9-6.8 mm/yr for Qt2 (NF). The cumulative slip rate across Millard Canyon (SF+NF) is therefore 1.8-11.6 mm/yr, or more narrowly constrained at 4.0-5.9 mm/yr by using only the overlapping slip rates along each fault strand. An average slip rate of ~5 mm/yr is ~30-70% of the slip rates outside of SGP. This 'slip deficit' may reflect some combination of slip carried by faults within in the San Bernardino Mountains to the north, transferred

  18. The 1998 March 14 Fandoqa earthquake (Mw 6.6) in Kerman province, southeast Iran: re-rupture of the 1981 Sirch earthquake fault, triggering of slip on adjacent thrusts and the active tectonics of the Gowk fault zone

    NASA Astrophysics Data System (ADS)

    Berberian, M.; Jackson, J. A.; Fielding, E.; Parsons, B. E.; Priestley, K.; Qorashi, M.; Talebian, M.; Walker, R.; Wright, T. J.; Baker, C.

    2001-08-01

    The 1998 March 14 Fandoqa earthquake (Ms6.6) was the penultimate in a series of five substantial earthquakes on the Gowk fault system of southeast Iran since 1981, all of which were associated with co-seismic surface ruptures. We use observations of surface faulting, analysis of P and SH body waves, SAR interferometry and geomorphology to investigate the ruptures in these earthquakes and how they are related both to each other and to the regional active tectonics. The 1998 Fandoqa earthquake produced 23km of surface faulting with up to 3m right-lateral strike-slip and 1m vertical offsets. SAR interferometry and seismic waveforms show that the main rupture plane dipped west at ~50° and had a normal component, although the surface ruptures were more complicated, being downthrown to both the east and the west on steep faults in near-surface sediments. In addition, SAR interferometry shows that a nearby thrust with a similar strike but dipping at ~6°W moved about 8cm in a time interval and in a position that makes it likely that its slip was triggered by the Fandoqa earthquake. The 1998 surface ruptures in the Gowk valley followed part of a much longer (~80km) set of co-seismic ruptures with smaller offsets that were observed after larger earthquakes in 1981 (Mw6.6 and 7.1). The main ruptures in these 1981 earthquakes probably occurred on different, deeper parts of the same fault system, producing only minor reactivation of the shallower faults at the surface. Although the 1981-1998 earthquake sequence apparently ruptured parts of the same fault system repeatedly, these earthquakes had very different rupture characteristics: an important lesson for the interpretation of both palaeoseismological trenching investigations and historical accounts of earthquakes. The regional kinematics, which involve oblique right-lateral and convergent motion, are evidently achieved by a complex configuration of faults with normal, reverse and strike-slip components. Some of the

  19. Longitudinal wheel slip during ABS braking

    NASA Astrophysics Data System (ADS)

    Hartikainen, Lassi; Petry, Frank; Westermann, Stephan

    2015-02-01

    Anti-lock braking system (ABS) braking tests with two subcompact passenger cars were performed on dry and wet asphalt, as well as on snow and ice surfaces. The operating conditions of the tyres in terms of wheel slip were evaluated using histograms of the wheel slip data. The results showed different average slip levels for different road surfaces. It was also found that changes in the tyre tread stiffness affected the slip operating range through a modification of the slip value at which the maximum longitudinal force is achieved. Variation of the tyre footprint length through modifications in the inflation pressure affected the slip operating range as well. Differences in the slip distribution between vehicles with different brake controllers were also observed. The changes in slip operating range in turn modified the relative local sliding speeds between the tyre and the road. The results highlight the importance of the ABS controller's ability to adapt to changing slip-force characteristics of tyres and provide estimates of the magnitude of the effects of different tyre and road operating conditions.

  20. Stabilizing Stick-Slip Friction

    NASA Astrophysics Data System (ADS)

    Fineberg, J.; Urbakh, M.; Rubinstein, S. M.

    2011-12-01

    Even the most regular stick-slip frictional sliding is always stochastic, with irregularity in both the intervals between slip events and the sizes of the associated stress drops. Applying small-amplitude oscillations to the shear force, we show, experimentally and theoretically, that the stick-slip periods synchronize. We further show that this phase locking is related to the inhibition of slow rupture modes which forces a transition to fast rupture, providing a possible mechanism for observed remote triggering of earthquakes. Such manipulation of collective modes may be generally relevant to extended nonlinear systems driven near to criticality. Reference: Rosario Capozza, Shmuel M. Rubinstein, Itay Barel, Michael Urbakh, and Jay Fineberg, Physical Review Letters 107, 024301 (2011).

  1. Tectonics, magmatism and fluid flow in a transtensional strike-slip setting: The northern termination of the Liquiñe-Ofqui fault System, Chile

    NASA Astrophysics Data System (ADS)

    Cembrano, J. M.; Perez-Flores, P.; Sánchez, P.; Sielfeld, G.

    2013-12-01

    vein systems, which appear to be associated with dextral strike-slip displacement on the LOFS. Fault-vein and vein structure varies from mineral fibers to typical ridge-and-groove striae. Bladed calcite occurs in dilational jogs along the main LOFS master faults; they are interpreted to represent boiling episodes. Thicker and more pervasive WNW sinistral-reverse fault-vein systems and breccias bodies suggest that the fault-valve mechanism was active during fluid transport and mineral precipitation. In some sites the WNW-striking system cuts and displaces the active LOFS, suggesting that their active has extended to at least the Pleistocene. Internally consistent structural and kinematic data from fault-fracture systems spatially and temporally associated with volcanoes and hydrothermal systems suggest that the same processes that drive the interplay between volcanism and tectonics may also control the nature, geometry and composition of geothermal reservoirs in the southern Andes.

  2. Large-scale right-slip displacement on the East San Francisco Bay Region fault system, California: Implications for location of late Miocene to Pliocene Pacific plate boundary

    USGS Publications Warehouse

    McLaughlin, R.J.; Sliter, W.V.; Sorg, D.H.; Russell, P.C.; Sarna-Wojcicki, A. M.

    1996-01-01

    A belt of northwardly younging Neogene and Quaternary volcanic rocks and hydrothermal vein systems, together with a distinctive Cretaceous terrane of the Franciscan Complex (the Permanente terrane), exhibits about 160 to 170 km of cumulative dextral offset across faults of the East San Francisco Bay Region (ESFBR) fault system. The offset hydrothermal veins and volcanic rocks range in age from .01 Ma at the northwest end to about 17.6 Ma at the southeast end. In the fault block between the San Andreas and ESFBR fault systems, where volcanic rocks are scarce, hydrothermal vein system ages clearly indicate that the northward younging thermal overprint affected these rocks beginning about 18 Ma. The age progression of these volcanic rocks and hydrothermal vein systems is consistent with previously proposed models that relate northward propagation of the San Andreas transform to the opening of an asthenospheric window beneath the North American plate margin in the wake of subducting lithosphere. The similarity in the amount of offset of the Permanente terrane across the ESFBR fault system to that derived by restoring continuity in the northward younging age progression of volcanic rocks and hydrothermal veins suggests a model in which 80-110 km of offset are taken up 8 to 6 Ma on a fault aligned with the Bloomfield-Tolay-Franklin-Concord-Sunol-Calaveras faults. An additional 50-70 km of cumulative slip are taken up ??? 6 Ma by the Rogers Creek-Hayward and Concord-Franklin-Sunol-Calaveras faults. An alternative model in which the Permanente terrane is offset about 80 km by pre-Miocene faults does not adequately restore the distribution of 8-12 Ma volcanic rocks and hydrothermal veins to a single northwardly younging age trend. If 80-110 km of slip was taken up by the ESFBR fault system between 8 and 6 Ma, dextral slip rates were 40-55 mm/yr. Such high rates might occur if the ESFBR fault system rather than the San Andreas fault acted as the transform margin at this time

  3. Relationship between the frequency magnitude distribution and the visibility graph in the synthetic seismicity generated by a simple stick-slip system with asperities.

    PubMed

    Telesca, Luciano; Lovallo, Michele; Ramirez-Rojas, Alejandro; Flores-Marquez, Leticia

    2014-01-01

    By using the method of the visibility graph (VG) the synthetic seismicity generated by a simple stick-slip system with asperities is analysed. The stick-slip system mimics the interaction between tectonic plates, whose asperities are given by sandpapers of different granularity degrees. The VG properties of the seismic sequences have been put in relationship with the typical seismological parameter, the b-value of the Gutenberg-Richter law. Between the b-value of the synthetic seismicity and the slope of the least square line fitting the k-M plot (relationship between the magnitude M of each synthetic event and its connectivity degree k) a close linear relationship is found, also verified by real seismicity. PMID:25162728

  4. Relationship between the Frequency Magnitude Distribution and the Visibility Graph in the Synthetic Seismicity Generated by a Simple Stick-Slip System with Asperities

    PubMed Central

    Telesca, Luciano; Lovallo, Michele; Ramirez-Rojas, Alejandro; Flores-Marquez, Leticia

    2014-01-01

    By using the method of the visibility graph (VG) the synthetic seismicity generated by a simple stick–slip system with asperities is analysed. The stick–slip system mimics the interaction between tectonic plates, whose asperities are given by sandpapers of different granularity degrees. The VG properties of the seismic sequences have been put in relationship with the typical seismological parameter, the b-value of the Gutenberg-Richter law. Between the b-value of the synthetic seismicity and the slope of the least square line fitting the k-M plot (relationship between the magnitude M of each synthetic event and its connectivity degree k) a close linear relationship is found, also verified by real seismicity. PMID:25162728

  5. Reconsidering Fault Slip Scaling

    NASA Astrophysics Data System (ADS)

    Gomberg, J. S.; Wech, A.; Creager, K. C.; Obara, K.; Agnew, D. C.

    2015-12-01

    The scaling of fault slip events given by the relationship between the scalar moment M0, and duration T, potentially provides key constraints on the underlying physics controlling slip. Many studies have suggested that measurements of M0 and T are related as M0=KfT3 for 'fast' slip events (earthquakes) and M0=KsT for 'slow' slip events, in which Kf and Ks are proportionality constants, although some studies have inferred intermediate relations. Here 'slow' and 'fast' refer to slip front propagation velocities, either so slow that seismic radiation is too small or long period to be measurable or fast enough that dynamic processes may be important for the slip process and measurable seismic waves radiate. Numerous models have been proposed to explain the differing M0-T scaling relations. We show that a single, simple dislocation model of slip events within a bounded slip zone may explain nearly all M0-T observations. Rather than different scaling for fast and slow populations, we suggest that within each population the scaling changes from M0 proportional to T3 to T when the slipping area reaches the slip zone boundaries and transitions from unbounded, 2-dimensional to bounded, 1-dimensional growth. This transition has not been apparent previously for slow events because data have sampled only the bounded regime and may be obscured for earthquakes when observations from multiple tectonic regions are combined. We have attempted to sample the expected transition between bounded and unbounded regimes for the slow slip population, measuring tremor cluster parameters from catalogs for Japan and Cascadia and using them as proxies for small slow slip event characteristics. For fast events we employed published earthquake slip models. Observations corroborate our hypothesis, but highlight observational difficulties. We find that M0-T observations for both slow and fast slip events, spanning 12 orders of magnitude in M0, are consistent with a single model based on dislocation

  6. Field and Laboratory Observations on Fluid Budget of the Cascadia Episodic Tremor and Slip System, Olympic Peninsula, Washington

    NASA Astrophysics Data System (ADS)

    Rotman, H.; Mattinson, C. G.

    2009-12-01

    Fluid movement in accretionary prisms has been linked to the recently discovered episodic tremor and slip (ETS) events along subduction zones. This study focuses on the exhumed accretionary prism of the Cascadia subduction zone, where ETS events are well-documented. The exposed sandstone, shale, siltstone and minor basalt in the study location were buried to 6 - 15 km, within the depth constraints of ETS. This past summer, field work focused on observations of subduction related fluid budget as evidenced by veins, metamorphism, and pore space took place along an east-west transect of the Olympic Peninsula. Approximately 40 representative samples were collected near Obstruction Peak, Hurricane Ridge, Lake Mills (Elwha), and Sore Thumb (Sol Duc). Observations indicate progressively increasing grade of metamorphism from west to east, in agreement with previous studies. Mudrocks show a clear progression from shale to phyllite, while sandstones generally appear equally micaceous across the transect, with the exception of one location. This location is unique in that micas are larger, other metamorphic indicators are visible in hand specimen, and veins make up a significant percent of the outcrop. Epidotes are visible in the rock body and veins, and the veins also contain quartz and calcite, usually as the primary mineral. Veins are oriented perpendicular to bedding and are primarily found in the coarser units. In addition to the veins, water is present in pore spaces and mineral structure. Preliminary observations indicate the veins and pore space decrease to the east, while evidence for fluid movement increases to the east. These observations will be tested and quantified by a variety of laboratory analyses. Thin section examination will determine pore space and mineral assemblages at different locations, and the mechanisms (e.g., blocky or fibrous) of vein growth. Element concentrations from whole rock analysis will determine bulk composition and element mobilization

  7. Re-evaluation of Fault Geometry and Slip Distribution of the 1944 Bolu-Gerede Earthquake Rupture, North Anatolian Fault System, Turkey

    NASA Astrophysics Data System (ADS)

    Kondo, H.; Awata, Y.; Emre, O.; Dogan, A.; Ozalp, S.; Tokay, F.; Yildirim, C.

    2002-12-01

    The successive earthquakes along the North Anatolian Fault System in 20th century provides us fundamental data on fault segmentation, characteristics faulting behavior, and dimensions and scaling laws of faulting. In this point of view, we re-evaluate geometry and slip-distribution of the Ms7.3 Bolu-Gerede earthquake rupture of 1944, which has not been studied since 1970. The 1944 rupture is traceable for about 185-km, from 30-km west of Bolu (40.6N, 31.4E) to 20-km west of Ilgaz (41.0N, 33.4E) almost continuously and straightly, trending N75E. Amount of slip along the rupture varies between 2 and 6 m right-laterally. In the middle-east section of the rupture, east of Gerede, the slip is as large as 4.5 to 6 m. Along the other sections, the amount of slip decreases to about 2-4 m. The rupture can be subdivided into 5 to 7 geometrical segments of 10 to 45-km-long, which are separated by small separation, bend, step, push-up and pull-apart structures. At 6-km east of Iametpasa (40.9N, 32.7E), a series of foundation of a stone-bridge, which is built approximately AD 680+190-90 (Ikeda, 1994), has been offset for about 20 m. The 3.5 to 4.0 m slip-per-event during the 1944 earthquakes suggests that the 20 m displacement has been accumulated by 5 to 6 faulting events with an average recurrence interval of about 200 to 350 years. Re-evaluated average slip of the 1944 rupture is about 3.5 m that is almost twice of the previously well-known amount. The straightness and continuance of the fault strands foresee that the 1944 earthquake had more simple rupture process and shorter source time than those of 1999 Izmit earthquake of Ms 7.4.

  8. Electro-optical hybrid slip ring

    NASA Astrophysics Data System (ADS)

    Hong, En

    2005-11-01

    The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

  9. Fault Slip Embedded in Creep: Insight into Tectonic Tremors and Slow Slip Events from Acoustic and Optical Monitoring of Fractures

    NASA Astrophysics Data System (ADS)

    Elkhoury, J. E.; Lengline, O.; Ampuero, J. P.; Schmittbuhl, J.

    2010-12-01

    Observations of temporal and spatial correlations between slow slip earthquakes and tectonic tremor activity suggest a physical relation between them. Early descriptions of mechanisms relating these phenomena simply attributed the relation between seismic and aseismic events to fluid mediated processes. More recent hypotheses suggest that tectonic tremors are bursts of seismic energy due to the rupturing of small asperities within slow slipping regions. Here we present laboratory results of a unique experimental setting aimed at understanding the response to transient loads of a system of small asperities embedded in creep as a model of tectonic tremor activity triggered by slow slip and modulated by tides. We performed mode I crack propagation experiments on glass bead blasted and annealed 2D interfaces of transparent material (Polymethylmethacrylate) where fracture fronts were confined to the 2D weakness plane of the heterogeneous interface. We monitored acoustic emissions (AE) with piezo-electric sensors surrounding the crack front line. We also optically monitored the rupture front line with up to 1000 frames per second. The experimental loading conditions produce quasi-static front propagation at slow average speeds. Image processing reveals de-pinning along the front that we characterize as intermittent opening during slow front propagation. AE locations strongly correlate to the spatiotemporal clustering of the de-penning events along the front. Moreover, this correlation is preserved at the time of imposed transient fluctuations in loading during front propagation. Using the analogy between mode I and modes II and III fractures, our results translate into intermittent slip on faults linked to clustering of seismic activity produced by the breakage of asperities embedded in creeping regions with no need of invoking fluid mediated processes. Thus our experiments help reveal the interplay between aseismic and seismic slip on faults. We also observe qualitative

  10. Slipped capital femoral epiphysis

    MedlinePlus

    A slipped capital femoral epiphysis is a separation of the ball of the hip joint from the thigh bone (femur) at ... A slipped capital femoral epiphysis may affect both hips. An epiphysis is an area at the end of a long bone . ...

  11. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  12. Distribution and structure of active strike-slip faults in the Enshu forearc basin of the eastern Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Ojima, T.; Ashi, J.; Nakamura, Y.

    2010-12-01

    Accretionary prisms and forearc basins are developed in the Nankai Trough, SW Japan. Many active faults are recognized and classified into five fault systems in the eastern Nankai Trough. The Enshu Faults System, the most landward one, runs over 200 km along the northern edge of the Tokai, Enshu and Kumano forearc basins. Swath bathymetry and side-scan sonar surveys indicate a general fault trend of ENE-WSW and dextral displacement of submarine canyons across the landward-most fault. Seismic reflection profiles partly exhibit landward dipping fault planes and flower structures suggesting that the Enshu fault system is affected by oblique subduction of the Philippines Sea Plate. Structural investigation of this area is important for earthquake disaster mitigation as well as understanding of oblique subduction tectonics. However, activity of faults has not been clarified. Japan Oil, Gas and Metal National Corporation (JOGMEC) conducted dense seismic reflection survey at the Tokai-Kumano area in 2001. Seismic reflection profiles clearly show depositional sequences and deformation structures such as faults and folds. This study examined deformation styles and fault activities based on detailed interpretation of seismic reflection profiles. Sediment thickness mapped from seismic profiles clearly changes with age. Sediment thickness is almost homogeneous from the acoustic basement (probably Paleogene Shimanto Complex) to a Pliocene horizon in the survey area. In contrast, thickness between a Pliocene horizon and present seafloor shows large variations from east to west. It is suggested that sedimentary environments change drastically at this period. There are also small-scale variations in sediment thickness for all horizons. Some distinct changes are distributed along linear boundaries. It seems that they correspond to the faults recognized as lineaments on the sidescan sonar images. We estimated activities of faulting based on such sediment thickness changes and their

  13. Characteristic slip behaviour of the Tabas fold system in eastern Iran: evidence from the 1978 Mw 7.3 Tabas-e-Golshan earthquake

    NASA Astrophysics Data System (ADS)

    Zhou, Yu; Walker, Richard; Hollingsworth, James; Song, Xiaogang; Talebian, Morteza; Parsons, Barry

    2016-04-01

    We use historical optical and modern satellite images to investigate the 1978 Mw 7.3 Tabas-e-Golshan earthquake in eastern Iran. Cross-correlation of images in 1974 and 1991 reveals a shortening component of ˜2.9 m on the Tabas fold, which is a combination of coseismic and post-seismic deformation. Image cross-correlation also shows ˜0.3 m shortening from 1991 to 2013. Using 6 pre-earthquake aerial photographs acquired in 1956 and a SPOT-6 stereo data set in 2013, we generate a pre- and post-earthquake digital elevation model (DEM) respectively, and by differencing the two DEMs, we measure a vertical displacement of ˜4.7 m. Models of the surface deformation field imply a total slip of 7 m from 1974 to 2013 on a 50° dipping fault, from a depth of 0.1 km to 6 km at the base, the majority of which (˜6.5 m) occurred prior to 1991. The slip appears to dissipate in the near surface. Our results, combined with the previous InSAR observations, indicate time-decaying shallow post-seismic afterslip, from ˜8 cm/yr in 1991-1996 to ˜5 mm/yr after 1996. Comparison of the fault slip model with the terrace heights measured from the SPOT-6 DEM suggests that the Tabas fold system exhibits a characteristic slip behaviour. Such behaviour would require a magnitude Mw 7.3 earthquake every ˜3500 years to accommodate the previously estimated shortening rate of ˜1.0 mm/yr. This study highlights the usefulness of historical imagery in investigating past earthquakes, thus providing new information about faulting in continental regions.

  14. X-slip: a physically-based model for the triggering of shallow rainfall-induced landslides, implemented in a GIS platform for alert systems

    NASA Astrophysics Data System (ADS)

    Montrasio, Lorella; Valentino, Roberto; Losi, Gian Luca

    2010-05-01

    A kind of landslide involving small scars of superficial soil, which is also called "soil slip", is usually triggered by short duration and intense rainfalls and mostly occurs on slopes composed of an impermeable bedrock and a shallow very permeable layer. Soil slips caused a lot of property damages and casualties in Italy and all over the world during the last few years. Since 1997, at the Department of Civil Engineering of University of Parma, has been carried out a research to develop a physically-based model to foresee the triggering of soil slips on spatial scale. The model has been validated, at local scale, on the basis of some case-histories. The model is deliberately simplified, in order to evaluate the safety factor of a slope in function of the geotechnical characteristic of soil, of geometrical features of the slope and of rainfall depth, which can be observed and forecasted. The model has been implemented in a platform for a real-time territory control, allowing the evaluation of regional soil slip susceptibility in the area of Emilia Romagna Region (Northern Italy). In the paper the model has been used to back analyse the occurrence of the phenomenon in some recent case-histories occurred in the Emilia Romagna Appennines, on 10-11th April 2005 and on 19-20th May 2008. A procedure of back analysis, based on observed rainfall depths, shows the capability of the model in matching, on a wide area, the occurrence of the phenomenon in the case-histories analysed. The input data for the model, which have been introduced through a GIS framework, include slope geometric features, the geotechnical characteristics of involved soils, both in saturated and unsaturated conditions, the drainage capability of the slope, the way of rainfall infiltration, the time varying rainfalls. The paper shows as the model could be capable of reaching the final aim of mapping susceptible zones and setting up an alert system for people against the analysed phenomena, if coupled

  15. Reduced Aftershock Productivity in Regions with Known Slow Slip Events

    NASA Astrophysics Data System (ADS)

    Collins, G.; Mina, A.; Richardson, E.; McGuire, J. J.

    2013-12-01

    Reduced aftershock activity has been observed in areas with high rates of aseismic slip, such as transform fault zones and some subduction zones. Fault conditions that could explain both of these observations include a low effective normal stress regime and/or a high temperature, semi-brittle/plastic rheology. To further investigate the possible connection between areas of aseismic slip and reduced aftershock productivity, we compared the mainshock-aftershock sequences in subduction zones where aseismic slip transients have been observed to those of adjacent (along-strike) regions where no slow slip events have been detected. Using the Advanced National Seismic System (ANSS) catalog, we counted aftershocks that occurred within 100 km and 14 days of 112 M>=5.0 slab earthquake mainshocks from January 1980 - July 2013, including 90 since January 2000, inside observed regions of detected slow slip: south central Alaska, Cascadia, the Nicoya Peninsula (Costa Rica), Guerrero (Mexico), and the North Island of New Zealand. We also compiled aftershock counts from 97 mainshocks from areas adjacent to each of these regions using the same criteria and over the same time interval. Preliminary analysis of these two datasets shows an aftershock triggering exponent (alpha in the ETAS model) of approximately 0.8, consistent with previous studies of aftershocks in a variety of tectonic settings. Aftershock productivity for both datasets is less than that of continental earthquakes. Contrasting the two datasets, aftershock productivity inside slow slip regions is lower than in adjacent areas along the same subduction zone and is comparable to that of mid-ocean ridge transform faults.

  16. Secondary Normal Faulting Near the Terminus of a Strike-Slip Fault Segment in the Lake Mead Fault System, SE Nevada

    NASA Astrophysics Data System (ADS)

    Marshall, S. T.; Kattenhorn, S. A.

    2003-12-01

    The 95 km long Lake Mead Fault System (LMFS), located about 50 km east of Las Vegas and about 100 km west of the relatively undeformed Colorado Plateau, consists of a group of NE/SW-trending Miocene left-lateral strike-slip faults with a total offset of 65-110 km. Previous work suggests that the LMFS acted as a transform zone to accommodate differential extension between the southern Basin and Range to the north and the metamorphic core complexes of the Colorado River extensional corridor to the south. Studies of individual faults of the LMFS have shown that strike-slip faulting was the dominant mode of deformation while normal faulting, pull-apart basins, and push up structures formed as localized secondary structures related to strike-slip faults. This study focuses on the portion of the LMFS west of the Overton Arm of Lake Mead, which consists of the Bitter Spring Valley Fault (BSVF) and the Hamblin Bay Fault (HBF). Both faults have estimated offsets of 20-60 km, but past mapping efforts have been inconsistent with respect to the BSVF trace locations and degree of fault complexity. In order to demonstrate that the apparent complexity of the BSVF is the result of segmentation and secondary normal faults associated with individual segments, we focused field mapping efforts on an apparent segment of the BSVF near Pinto Ridge, located southwest of the Echo Hills and about 5 km NW of the more prominent HBF. We have identified nine normal faults that initiate near the SW tip of a segment of the BSVF and die out to the south before reaching the HBF. The offset on all these faults is a maximum at their northern intersection with the BSVF, then steadily decreases to zero away from the BSVF. These normal faults range from 0.6 km-2.25 km in length and have variable fault trace patterns. The normal fault originating closest to the SW tip of the BSVF segment curves with increasing distance away towards parallelism with the BSVF. The eight other normal faults are all oriented

  17. Slipped Capital Femoral Epiphysis

    MedlinePlus

    ... is held in place with a single central screw. This screw keeps the thigh bone from slipping and will ... including in-situ fixation with more than one screw) are used less often. Ask your doctor to ...

  18. Atomistically determined phase-field modeling of dislocation dissociation, stacking fault formation, dislocation slip, and reactions in fcc systems

    NASA Astrophysics Data System (ADS)

    Rezaei Mianroodi, Jaber; Svendsen, Bob

    2015-04-01

    The purpose of the current work is the development of a phase field model for dislocation dissociation, slip and stacking fault formation in single crystals amenable to determination via atomistic or ab initio methods in the spirit of computational material design. The current approach is based in particular on periodic microelasticity (Wang and Jin, 2001; Bulatov and Cai, 2006; Wang and Li, 2010) to model the strongly non-local elastic interaction of dislocation lines via their (residual) strain fields. These strain fields depend in turn on phase fields which are used to parameterize the energy stored in dislocation lines and stacking faults. This energy storage is modeled here with the help of the "interface" energy concept and model of Cahn and Hilliard (1958) (see also Allen and Cahn, 1979; Wang and Li, 2010). In particular, the "homogeneous" part of this energy is related to the "rigid" (i.e., purely translational) part of the displacement of atoms across the slip plane, while the "gradient" part accounts for energy storage in those regions near the slip plane where atomic displacements deviate from being rigid, e.g., in the dislocation core. Via the attendant global energy scaling, the interface energy model facilitates an atomistic determination of the entire phase field energy as an optimal approximation of the (exact) atomistic energy; no adjustable parameters remain. For simplicity, an interatomic potential and molecular statics are employed for this purpose here; alternatively, ab initio (i.e., DFT-based) methods can be used. To illustrate the current approach, it is applied to determine the phase field free energy for fcc aluminum and copper. The identified models are then applied to modeling of dislocation dissociation, stacking fault formation, glide and dislocation reactions in these materials. As well, the tensile loading of a dislocation loop is considered. In the process, the current thermodynamic picture is compared with the classical mechanical

  19. Electrostatic precursors to granular slip events

    PubMed Central

    Shinbrot, Troy; Kim, Nam H.; Thyagu, N. Nirmal

    2012-01-01

    It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials. PMID:22689956

  20. Dynamical Stability of Slip-stacking Particles

    SciTech Connect

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-04

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  1. Friction of water slipping in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Ming D.; Shen, Luming; Sheridan, John; Liu, Jefferson Zhe; Chen, Chao; Zheng, Quanshui

    2011-03-01

    Liquid slip is essential in nanofluidic systems, as shrinking channel size leads to a dramatic increase in flow resistance and thus high-energy consumption for driving nonslip flow. Using large-scale nonequilibrium molecular dynamics simulation of water flowing in carbon nanotubes (CNT’s), we show that the relationship between the CNT wall-water interfacial friction stress and slip velocity follows a transition-state-theory-based inverse hyperbolic sine function, which remains universally valid regardless of wetting properties, CNT chiralities, and CNT sizes, and holds for all slip velocities from 0 to 1400 m/s. The finding could benefit the research in desalination and other chemical purification techniques.

  2. Slip mechanisms in complex fluid flows.

    PubMed

    Hatzikiriakos, Savvas G

    2015-10-28

    The classical no-slip boundary condition of fluid mechanics is not always a valid assumption for the flow of several classes of complex fluids including polymer melts, their blends, polymer solutions, microgels, glasses, suspensions and pastes. In fact, it appears that slip effect in these systems is the rule and not the exemption. The occurrence of slip complicates the analysis of rheological data, although it provides new opportunities to understand their behavior in restricted environments delineating additional molecular mechanisms i.e. entropic restrictions due to limitations in the number of molecular conformations. This article discusses these complexities and provides future research opportunities. PMID:26345121

  3. Dynamical stability of slip-stacking particles

    NASA Astrophysics Data System (ADS)

    Eldred, Jeffrey; Zwaska, Robert

    2014-09-01

    We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

  4. Active optical zoom system

    DOEpatents

    Wick, David V.

    2005-12-20

    An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

  5. SLIP CASTING METHOD

    DOEpatents

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  6. The Border Ranges fault system in Glacier Bay National Park, Alaska: Evidence for major early Cenozoic dextral strike-slip motion

    USGS Publications Warehouse

    Smart, K.J.; Pavlis, T.L.; Sisson, V.B.; Roeske, S.M.; Snee, L.W.

    1996-01-01

    The Border Ranges fault system of southern Alaska, the fundamental break between the arc basement and the forearc accretionary complex, is the boundary between the Peninsular-Alexander-Wrangellia terrane and the Chugach terrane. The fault system separates crystalline rocks of the Alexander terrane from metamorphic rocks of the Chugach terrane in Glacier Bay National Park. Mylonitic rocks in the zone record abundant evidence for dextral strike-slip motion along north-northwest-striking subvertical surfaces. Geochronologic data together with regional correlations of Chugach terrane rocks involved in the deformation constrain this movement between latest Cretaceous and Early Eocene (???50 Ma). These findings are in agreement with studies to the northwest and southeast along the Border Ranges fault system which show dextral strike-slip motion occurring between 58 and 50 Ma. Correlations between Glacier Bay plutons and rocks of similar ages elsewhere along the Border Ranges fault system suggest that as much as 700 km of dextral motion may have been accommodated by this structure. These observations are consistent with oblique convergence of the Kula plate during early Cenozoic and forearc slivering above an ancient subduction zone following late Mesozoic accretion of the Peninsular-Alexander-Wrangellia terrane to North America.

  7. Slip-Related Changes in Plantar Pressure Distribution, and Parameters for Early Detection of Slip Events

    PubMed Central

    Choi, Seungyoung; Cho, Hyungpil; Kang, Boram; Lee, Dong Hun; Kim, Mi Jung

    2015-01-01

    Objective To investigate differences in plantar pressure distribution between a normal gait and unpredictable slip events to predict the initiation of the slipping process. Methods Eleven male participants were enrolled. Subjects walked onto a wooden tile, and two layers of oily vinyl sheet were placed on the expected spot of the 4th step to induce a slip. An insole pressure-measuring system was used to monitor plantar pressure distribution. This system measured plantar pressure in four regions (the toes, metatarsal head, arch, and heel) for three events: the step during normal gait; the recovered step, when the subject recovered from a slip; and the uncorrected, harmful slipped step. Four variables were analyzed: peak pressure (PP), contact time (CT), the pressure-time integral (PTI), and the instant of peak pressure (IPP). Results The plantar pressure pattern in the heel was unique, as compared with other parts of the sole. In the heel, PP, CT, and PTI values were high in slipped and recovered steps compared with normal steps. The IPP differed markedly among the three steps. The IPPs in the heel for the three events were, in descending order (from latest to earliest), slipped, recovered, and normal steps, whereas in the other regions the order was normal, recovered, and slipped steps. Finally, the metatarsal head-to-heel IPP ratios for the normal, recovered, and slipped steps were 6.1±2.9, 3.1±3.0, and 2.2±2.5, respectively. Conclusion A distinctive plantar pressure pattern in the heel might be useful for early detection of a slip event to prevent slip-related injuries. PMID:26798603

  8. Uncorking Shallow Slip and the Slip History of the 2014 South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Brooks, B. A.; Minson, S. E.; Glennie, C. L.; Murray, J. R.; Hudnut, K. W.; Ericksen, T.; Langenheim, V. E.; Lockner, D. A.; Dawson, T. E.; Lutz, A. T.; Schwartz, D. P.; Lienkaemper, J. J.

    2015-12-01

    Shallow fault slip (< ~1km) during and immediately following earthquakes is poorly understood, largely because of challenges measuring deformation near a surface rupture. The need for better measurement is further motivated by an apparent deficit of shallow slip in regional source models of strike-slip earthquakes and by the suggestion that near-surface frictional heterogeneity over spatial scales of 100s of meters can control shallow fault slip. Here, we use a nascent mobile laser scanning technique to quantify with unprecedented detail the coseismic surface rupture and rapid post-seismic deformation from the 24 August, 2014 M6.0 South Napa earthquake. We infer shallow fault slip and find that both co- and post-seismic slip at depths of ~3-25 m significantly exceeds traditional measurements of surface displacements. There is no deficit in shallow slip: near-surface slip values are greater than maximum reported co-seismic fault slip values at depth. By ~ 1 month, afterslip along the southern portion of the fault accounted for as much shallow slip potency as the shallow co-seismic rupture on the northern portion. Further, we show that the afterslipping portion of the fault cuts across a ~3000 m thick sedimentary basin whereas the co-seismically ruptured portion does not. A rate and state friction model is consistent with the basin thickness, afterslip, and rock-sample mechanical measurements and strongly suggests that near-surface frictional heterogeneity controlled the distribution of coseismic and post-seismic shallow slip. In the future, we suggest that combining existing basin thickness data with active fault maps could provide more precise estimates of where surface rupture and/or afterslip may occur, both before, and in rapid response to, damaging earthquakes.

  9. Origin and characterization of different stick-slip friction mechanisms

    SciTech Connect

    Berman, A.D.; Ducker, W.A.; Israelachvili, J.N.

    1996-09-18

    Mechanical parts often move, not smoothly, but in jerks known as stick-slip. Stick-slip motion may be regular (repetitive or periodic) or irregular (erratic or intermittent). In the case of frictional sliding, stick-slip can have serious and often undesirable consequences - resulting in noise (chatter), high energy loss (friction), surface damage (wear), and component failure. We review the origins of stick-slip friction and present new experimental results on model surfaces that clarify its different origins, its dependence on experimental conditions or `system parameters`, and how stick-slip can be controlled in practical situations. 20 refs., 10 figs., 1 tab.

  10. Fluid-controlled grain boundary migration and switch in slip systems in a high strain, high temperature contact aureole, California, USA

    NASA Astrophysics Data System (ADS)

    Morgan, Sven S.; Nabelek, Peter I.; Student, James; Sadorski, Joseph F.

    2016-04-01

    Within the highly strained aureole surrounding the Eureka Valley-Joshua Flat-Beer Creek (EJB) composite pluton of eastern California, an inversion in microstructures and crystallographic preferred orientations (CPOs) exists with distance from the contact. An inner aureole (< 250 m from the contact) consists of quartzites that are interbedded with marbles and calc-silicates. These quartzites are incompletely recrystallized. Most grain boundaries have migrated, although it is clear that grain boundary migration (GBM) is not extensive. Multiple data sets indicate that temperatures of deformation were above 650 °C. CPOs are indicative of < a > slip in quartz. Within the outer aureole (250 m to 1500 m from the contact), quartzites are interbedded with pelitic schist and are completely recrystallized and microstructures are indicative of extensive GBM. CPOs are indicative of prism [c] slip. Oxygen isotope ratios in the inner aureole are only slightly shifted from their original values. Oxygen isotopes from the outer aureole are shifted more, which is consistent with equilibration with locally derived fluids. We suggest that recrystallization in the outer aureole was aided by pore water, water derived from fluid inclusions, and water generated by prograde reactions in the schists. The pore fluids in the inner aureole were also probably initially water-rich. However, during prograde reactions in the intervening calc-silicate rocks, and perhaps more importantly, between calcite cement and quartz in the quartzites, the pore fluid composition in the inner aureole changed to become dominated by CO2, which acted as a non-wetting phase and decreased the fugacity of water slowing grain boundary mobility. Low water fugacity also suppressed the activity of prism [c] slip. Therefore, we propose that dry conditions or a grain boundary fluid with a significant non-wetting component (CO2) can result in apparent temperatures of deformation that are more than 100 °C lower than the real

  11. GPS Versus Seismological Observations in two Seismogenic Zones in the Adria-Alps- Pannon System; Block Motion vs. Diffuse Deformation, Increased Earthquake Potential vs. Aseismic Slip

    NASA Astrophysics Data System (ADS)

    Grenerczy, G.; Bus, Z.; Toth, L.; Monus, P.

    2008-12-01

    The tectonic activity, seismicity and the associated seismic hazard is highly variable in the Adria-Alps-Pannon region. The engine of the system is the Adria microplate that compresses a puzzle of crustal blocks towards the European Platform. Based on seismicity and data of continuous and campaign style GPS measurements between 1991 and 2007 we investigated the existence of different blocks and their present kinematics. At the resolution and signal level we have, deformation seems to be more diffuse and block motion is no longer recognizable over the Pannonian basin towards the Carpathains. Although towards the basin seismicity decreases to moderate, the vulnerability is still high, as three capital cities are located near to the two most active seismic zones in this subregion. Each cities and their suburbs produce about 30- 40 % of the GDP of the respective countries. In the second par of our analysis these two seismically active areas, the Mur-Murz and Central Pannonian zones, are investigated. Uniform strain rates and relative displacements were calculated for these regions. The GPS data confirm the mostly left lateral strike slip character of the Mur-Murz fault zone and suggest a contraction between the eastward moving Alpine-North Pannonian unit and the Carpathians. The computation of the seismic strain rate was based on the Kostrov summation. The averaged unit norm seismic moment tensor, which describes the characteristic style of deformation, has been obtained by using the available focal mechanism solutions, whereas the annual seismic moment release showing the rate of the deformation was estimated using the catalogs of historical and recent earthquakes. Our analysis reveals that in both zones the geodetic strain rate is significantly larger than the seismic deformation. Based on the weakness of the lithosphere, the stress magnitudes and the regional features of seismicity, we suggest that the low value of the seismic/geodetic strain rate ratio in the

  12. Behavior of aircraft antiskid breaking systems on dry and wet runway surfaces: A slip-ratio-controlled system with ground speed reference from unbraked nose wheel

    NASA Technical Reports Server (NTRS)

    Tanner, J. A.; Stubbs, S. M.

    1977-01-01

    An experimental investigation was conducted at the Langley aircraft landing loads and traction facility to study the braking and cornering response of a slip ratio controlled aircraft antiskid braking system with ground speed reference derived from an unbraked nose wheel. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a DC-9 series 10 airplane. During maximum braking, the average ratio of the drag force friction coefficient developed by the antiskid system to the maximum drag force friction coefficient available was higher on the dry surface than on damp and flooded surfaces, and was reduced with lighter vertical loads, higher yaw angles, and when new tire treads were replaced by worn treads. Similarly, the average ratio of side force friction coefficient developed by the tire under antiskid control to the maximum side force friction coefficient available to a freely rolling yawed tire decreased with increasing yaw angle, generally increased with ground speed, and decreased when tires with new treads were replaced by those with worn treads.

  13. Hairpin river loops and slip-sense inversion on southeast Asian strike-slip faults

    NASA Astrophysics Data System (ADS)

    Lacassin, Robin; Replumaz, Anne; Hervé Leloup, P.

    1998-08-01

    In the Golden Triangle region of southeast Asia (northern Thailand, Laos and Burma, southern Yunnan), the Mekong, Salween, and neighboring rivers show hairpin geometries where they cross active strike-slip faults. Restoration of young, left-lateral offsets of these rivers leaves residual right-lateral bends of many kilometers. We interpret these hairpins as evidence of late Cenozoic slip-sense inversion on these faults, about 5 to 20 Ma. Near the Red River fault, stress field and slip-sense inversion occurred ca. 5 Ma. This implies that the present course of these large rivers has existed for at least several million years. Pliocene Quaternary slip rates, possibly on the order of 1 mm/yr, are inferred on each of the strike-slip faults of the Golden Triangle.

  14. Fluid-flow model of high-porosity carbonates crosscut by a strike-slip fault system, Favignana Island (southern Italy)

    NASA Astrophysics Data System (ADS)

    Cilona, Antonino; Antonellini, Marco; Tondi, Emanuele; Agosta, Fabrizio; Johnson, Gareth; Shackleton, Ryan

    2013-04-01

    This contribution integrates structural analysis and numerical modelling to build up, from outcrop data, a 3D Discrete Fracture Network (DFN) model, and then to run fluid flow simulations of a porous carbonate reservoir. A semi-automated process of lineament analysis, followed by the use of power law distributions to model sub-seismic scale features, is here proposed as a workflow for reservoir-scale assessment of the control exerted by structural features on the bulk permeability in porous carbonate reservoirs. In Favignana Island (southern Italy), several quarries provide an excellent 3D view of Lower-Pleistocene grainstones crosscut by a strike-slip fault system. This fault system is made up of two main conjugate sets of strike-slip structural features such as Compactive Shear Bands (CSB), Zones of compactive shear Bands (ZB) and faults. The multi-scale properties of the aforementioned elements, distinguished for individual sets, have been previously assessed by mean of detailed scan-line and scan-area measurements. The DFN model was built using the Fracture Modelling module within the MOVE software package from Midland Valley. Analysis of an aerial photo was performed to identify the major faults. The intensity of CSBs and ZBs was computed after a preliminary outcrop analysis. We used the variation in intensity to build a DFN that reflects a pattern of deformation similar to the natural structural framework. It is well known that both CSBs and ZBs reduce permeability, whilst slip surfaces present within faults enhance fault-parallel fluid flow. The obtained DFN was used, hence, to model the effect of deformation on host rock permeability by imposing a reduced porosity of the CSBs and ZBs relative to both host rock and slip surfaces. By taking advantage of the computed distribution of both porosity and permeability within the modelled rock volume, fluid flow simulations have been carried out by solving the flow and transport equations with finite elements. In

  15. Basal slip and mechanical anisotropy of biotite

    SciTech Connect

    Kronenberg, A.K. ); Kirby, S.H.; Pinkston, J. )

    1990-11-10

    The basal slip systems of biotite and their mechanical expressions have been investigated by shortening single crystals oriented to maximize and minimize shear stresses on (001). Samples loaded at 45{degree} to (001) exhibit gentle external rotations associated with dislocation glide. Samples shortened perpendicular to (001) show no evidence of nonbasal slip and fail by fracture over all conditions tested. The mechanical response of biotite shortened at 45{degree} to (001) is nearly perfectly elastic-plastic; stress-strain curves are characterized by a steep elastic slope, a sharply defined yield point, and continued deformation at low (mostly < 100 MPa), relatively constant stresses at strains >1%. Stresses measured beyond the yield point are insensitive to confining pressure over the range 200 to 500 MPa and exhibit weak dependencies upon strain rate and temperature. Assuming an exponential relationship between differential stress {sigma}{sub d} and strain rate {epsilon} = C exp({minus}Q/RT), the data collected over strain rates and temperatures of 10-7 to 10-4 s-1 and 20 to 400C, respectively, are best fit by an exponential constant {alpha} of 0.41 {plus minus} 0.08 MPa{minus}1 and an activation energy Q of 82 {plus minus} 13 kJ/mol. A power law fits the data equally well with n = 18 {plus minus} 4 and Q = 51 {plus minus} 9 kJ/mol. The strength of biotite shortened perpendicular to (001) exceeds that measured parallel to (001) and is pressure dependent. Application of the results to deformation within the continental crust suggests that biotite oriented favorably for slip is much weaker than most silicates over a wide range of geologic conditions. Its presence within foliated rocks and shear zones may limit locally the stresses that can be supported.

  16. SLIPPING MAGNETIC RECONNECTION TRIGGERING A SOLAR ERUPTION OF A TRIANGLE-SHAPED FLAG FLUX ROPE

    SciTech Connect

    Li, Ting; Zhang, Jun E-mail: zjun@nao.cas.cn

    2014-08-10

    We report the first simultaneous activities of the slipping motion of flare loops and a slipping eruption of a flux rope in 131 Å and 94 Å channels on 2014 February 2. The east hook-like flare ribbon propagated with a slipping motion at a speed of about 50 km s{sup –1}, which lasted about 40 minutes and extended by more than 100 Mm, but the west flare ribbon moved in the opposite direction with a speed of 30 km s{sup –1}. At the later phase of flare activity, there was a well developed ''bi-fan'' system of flare loops. The east footpoints of the flux rope showed an apparent slipping motion along the hook of the ribbon. Simultaneously, the fine structures of the flux rope rose up rapidly at a speed of 130 km s{sup –1}, much faster than that of the whole flux rope. We infer that the east footpoints of the flux rope are successively heated by a slipping magnetic reconnection during the flare, which results in the apparent slippage of the flux rope. The slipping motion delineates a ''triangle-shaped flag surface'' of the flux rope, implying that the topology of a flux rope is more complex than anticipated.

  17. Support for the slip hypothesis from whisker-related tactile perception of rats in a noisy environment

    PubMed Central

    Waiblinger, Christian; Brugger, Dominik; Whitmire, Clarissa J.; Stanley, Garrett B.; Schwarz, Cornelius

    2015-01-01

    Rodents use active whisker movements to explore their environment. The “slip hypothesis” of whisker-related tactile perception entails that short-lived kinematic events (abrupt whisker movements, called “slips”, due to bioelastic whisker properties that occur during active touch of textures) carry the decisive texture information. Supporting this hypothesis, previous studies have shown that slip amplitude and frequency occur in a texture-dependent way. Further, experiments employing passive pulsatile whisker deflections revealed that perceptual performance based on pulse kinematics (i.e., signatures that resemble slips) is far superior to the one based on time-integrated variables like frequency and intensity. So far, pulsatile stimuli were employed in a noise free environment. However, the realistic scenario involves background noise (e.g., evoked by rubbing across the texture). Therefore, if slips are used for tactile perception, the tactile neuronal system would need to differentiate slip-evoked spikes from those evoked by noise. To test the animals under these more realistic conditions, we presented passive whisker-deflections to head-fixed trained rats, consisting of “slip-like” events (waveforms mimicking slips occurring with touch of real textures) embedded into background noise. Varying the (i) shapes (ramp or pulse); (ii) kinematics (amplitude, velocity, etc.); and (iii) the probabilities of occurrence of slip-like events, we observed that rats could readily detect slip-like events of different shapes against noisy background. Psychophysical curves revealed that the difference of slip event and noise amplitude determined perception, while increased probability of occurrence (frequency) had barely any effect. These results strongly support the notion that encoding of kinematics dominantly determines whisker-related tactile perception while the computation of frequency or intensity plays a minor role. PMID:26528148

  18. Cyclical Stress Field Switching and (Total?) Relief of Fault Shear Stress Recorded in Quartz Vein Systems Hosted by Proterozoic Strike-Slip Faults, Mt Isa, Australia

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.; Begbie, M. J.; Ghisetti, F. C.; Blenkinsop, T. G.

    2003-12-01

    slip increments. A preliminary interpretation is that the differently oriented systematic vein-sets reflect changing orientations of the local stress field at different stages of the earthquake stress cycle. Minimum compressional stress oblique to the fault through the interseismic interval alternates with minimum compression oriented subperpendicular to the fault immediately postfailure, suggesting that each slip episode was accompanied by near-total relief of shear stress along the fault. The presence of amethystine quartz, open-space filling textures, and calcite-quartz intergrowths in the vein sets are consistent with hydrothermal precipitation occurring within 1-2 km of the former ground surface. Consequently, it is not yet clear whether these extensive vein systems developed under hydrostatic or overpresssured fluid conditions.

  19. Novel Cross-Slip Mechanism of Pyramidal Screw Dislocations in Magnesium.

    PubMed

    Itakura, Mitsuhiro; Kaburaki, Hideo; Yamaguchi, Masatake; Tsuru, Tomohito

    2016-06-01

    Compared to cubic metals, whose primary slip mode includes twelve equivalent systems, the lower crystalline symmetry of hexagonal close-packed metals results in a reduced number of equivalent primary slips and anisotropy in plasticity, leading to brittleness at the ambient temperature. At higher temperatures, the ductility of hexagonal close-packed metals improves owing to the activation of secondary ⟨c+a⟩ pyramidal slip systems. Thus, understanding the fundamental properties of corresponding dislocations is essential for the improvement of ductility at the ambient temperature. Here, we present the results of large-scale ab initio calculations for ⟨c+a⟩ pyramidal screw dislocations in magnesium and show that their slip behavior is a stark counterexample to the conventional wisdom that a slip plane is determined by the stacking fault plane of dislocations. A stacking fault between dissociated partial dislocations can assume a nonplanar shape with a negligible energy cost and can migrate normal to its plane by a local shuffling of atoms. Partial dislocations dissociated on a {21[over ¯]1[over ¯]2} plane "slither" in the {011[over ¯]1} plane, dragging the stacking fault with them in response to an applied shear stress. This finding resolves the apparent discrepancy that both {21[over ¯]1[over ¯]2} and {011[over ¯]1} slip traces are observed in experiments while ab initio calculations indicate that dislocations preferably dissociate in the {21[over ¯]1[over ¯]2} planes. PMID:27314728

  20. Novel Cross-Slip Mechanism of Pyramidal Screw Dislocations in Magnesium

    NASA Astrophysics Data System (ADS)

    Itakura, Mitsuhiro; Kaburaki, Hideo; Yamaguchi, Masatake; Tsuru, Tomohito

    2016-06-01

    Compared to cubic metals, whose primary slip mode includes twelve equivalent systems, the lower crystalline symmetry of hexagonal close-packed metals results in a reduced number of equivalent primary slips and anisotropy in plasticity, leading to brittleness at the ambient temperature. At higher temperatures, the ductility of hexagonal close-packed metals improves owing to the activation of secondary ⟨c +a ⟩ pyramidal slip systems. Thus, understanding the fundamental properties of corresponding dislocations is essential for the improvement of ductility at the ambient temperature. Here, we present the results of large-scale ab initio calculations for ⟨c +a ⟩ pyramidal screw dislocations in magnesium and show that their slip behavior is a stark counterexample to the conventional wisdom that a slip plane is determined by the stacking fault plane of dislocations. A stacking fault between dissociated partial dislocations can assume a nonplanar shape with a negligible energy cost and can migrate normal to its plane by a local shuffling of atoms. Partial dislocations dissociated on a {2 1 ¯ 1 ¯ 2 } plane "slither" in the {01 1 ¯1 } plane, dragging the stacking fault with them in response to an applied shear stress. This finding resolves the apparent discrepancy that both {2 1 ¯1 ¯2 } and {01 1 ¯1 } slip traces are observed in experiments while ab initio calculations indicate that dislocations preferably dissociate in the {2 1 ¯1 ¯2 } planes.

  1. Active fault database of Japan: Its construction and search system

    NASA Astrophysics Data System (ADS)

    Yoshioka, T.; Miyamoto, F.

    2011-12-01

    The Active fault database of Japan was constructed by the Active Fault and Earthquake Research Center, GSJ/AIST and opened to the public on the Internet from 2005 to make a probabilistic evaluation of the future faulting event and earthquake occurrence on major active faults in Japan. The database consists of three sub-database, 1) sub-database on individual site, which includes long-term slip data and paleoseismicity data with error range and reliability, 2) sub-database on details of paleoseismicity, which includes the excavated geological units and faulting event horizons with age-control, 3) sub-database on characteristics of behavioral segments, which includes the fault-length, long-term slip-rate, recurrence intervals, most-recent-event, slip per event and best-estimate of cascade earthquake. Major seismogenic faults, those are approximately the best-estimate segments of cascade earthquake, each has a length of 20 km or longer and slip-rate of 0.1m/ky or larger and is composed from about two behavioral segments in average, are included in the database. This database contains information of active faults in Japan, sorted by the concept of "behavioral segments" (McCalpin, 1996). Each fault is subdivided into 550 behavioral segments based on surface trace geometry and rupture history revealed by paleoseismic studies. Behavioral segments can be searched on the Google Maps. You can select one behavioral segment directly or search segments in a rectangle area on the map. The result of search is shown on a fixed map or the Google Maps with information of geologic and paleoseismic parameters including slip rate, slip per event, recurrence interval, and calculated rupture probability in the future. Behavioral segments can be searched also by name or combination of fault parameters. All those data are compiled from journal articles, theses, and other documents. We are currently developing a revised edition, which is based on an improved database system. More than ten

  2. Application of Anti-slip/skid Re-adhesion Control System Based on Disturbance Observer to a Skid Control Considering Cooperation Control of Air Bake and Electric Brake

    NASA Astrophysics Data System (ADS)

    Kadowaki, Satoshi; Ohishi, Kiyoshi; Sano, Takashi; Yasukawa, Shinobu

    We have already proposed the anti-slip re-adhesion control based on disturbance observer and sensor-less vector control at acceleration mode. This paper proposes a new anti-skid re-adhesion control based on disturbance observer at braking mode. The numerical simulation and experimental results point out that the proposed anti-skid re-adhesion control system has the desired driving wheel torque response for the tested bogie system of electric train. An actual train uses both electric brake and air brake in the high-speed range. Hence, this paper proposes a new anti-skid re-adhesion control considering the air brake, which carries out the cooperation control of electric brake and air brake in order to realize a fine re-adhesion control. The numerical simulation results point out that the proposed system has the desired driving wheel torque response and a fine anti-skid re-adhesion control.

  3. Lower extremity corrective reactions to slip events.

    PubMed

    Cham, R; Redfern, M S

    2001-11-01

    A significant number of injuries in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether the outcome of a slip will be recovery or a fall. The goal of this study was to examine lower extremity joint moments and postural adjustments for experimental evidence of corrective strategies evoked during slipping in an attempt to prevent falling. Sixteen subjects walked onto a possibly oily vinyl tile floor, while ground reaction forces and body motion were recorded at 350 Hz. The onset of corrective reactions by the body in an attempt to recover from slips became evident at about 25% of stance and continued until about 45% into stance, i.e. on average between 190 and 350 ms after heel contact. These reactions included increased flexion moment at the knee and extensor activity at the hip. The ankle, on the other hand, acted as a passive joint (no net moment) during fall trials. Joint kinematics showed increased knee flexion and forward rotation of the shank in an attempt to bring the foot back towards the body. Once again, the ankle kinematics appeared to play a less dominant role (compared to the knee) in recovery attempts. This study indicates that humans generate corrective reactions to slips that are different than previously reported responses to standing perturbations translating the supporting surface. PMID:11672718

  4. Slow Slip, Tremor and the Multi-Scale Mechanics of Heterogeneous Faults

    NASA Astrophysics Data System (ADS)

    Ampuero, J. P.

    2012-12-01

    A now widespread view of slow slip and tectonic tremor activity involves faults with a highly heterogeneous mechanical behavior, in which tremor sources result from shear failure of a multitude of compact asperities (frictionally unstable regions capable of seismic slip) embedded in creeping fault regions (frictionally stable zones capable of aseismic transient slip). Coarse resolution geodetic observations of slow slip and fine resolution seismological observations of tremor migration patterns provide an opportunity to investigate the mechanical behavior of a complex natural system at multiple scales. I will provide a synthesis of ongoing studies of slow slip and tremor activity through computational modeling and analog experimental approaches within the framework of heterogeneous faults. A similar view of the structure of subduction fault zones has emerged from observations of low and high frequency slip in recent megathrust earthquakes. Simulations of the collective behavior of asperities embedded in creeping faults generate a rich spectrum of migration patterns, some of which are observed in natural faults. The seismicity rate, recurrence time and migration speed of these tremor swarms are mechanically related to the underlying transient slow slip. This provides a physical basis for using tremor activity as a natural creepmeter. This implies that, if aseismic slip transients preceding large earthquakes are large enough at tremor depths, changes of tremor activity patterns may indicate the approach to a large seismic event. Numerical models are developed to assess if this is viable. Tremor activity also responds to periodic loadings induced by tides or surface waves. Our recent models show that this response can be efficiently mediated by transient response of the surrounding creep. Fault regions close to neutral-stability are shown to be very sensitive to periodic loading within a broad range of periods. The sensitive range depends on frictional properties and

  5. Fault-slip accumulation in an active rift over thousands to millions of years and the importance of paleoearthquake sampling

    NASA Astrophysics Data System (ADS)

    Mouslopoulou, Vasiliki; Nicol, Andrew; Walsh, John; Begg, John; Townsend, Dougal; Hristopulos, Dionissios

    2013-04-01

    The catastrophic earthquakes that recently (September 4th, 2010 and February 22nd, 2011) hit Christchurch, New Zealand, show that active faults, capable of generating large-magnitude earthquakes, can be hidden beneath the Earth's surface. In this study we combine near-surface paleoseismic data with deep (<5 km) onshore seismic-reflection lines to explore the growth of normal faults over short (<27 kyr) and long (>1 Ma) timescales in the Taranaki Rift, New Zealand. Our analysis shows that the integration of different timescale datasets provides a basis for identifying active faults not observed at the ground surface, estimating maximum fault-rupture lengths, inferring maximum short-term displacement rates and improving earthquake hazard assessment. We find that fault displacement rates become increasingly irregular (both faster and slower) on shorter timescales, leading to incomplete sampling of the active-fault population. Surface traces have been recognised for <50% of the active faults and along ∼50% of their lengths. The similarity of along-strike displacement profiles for short and long time intervals suggests that fault lengths and maximum single-event displacements have not changed over the last 3.6 Ma. Therefore, rate changes are likely to reflect temporal adjustments in earthquake recurrence intervals due to fault interactions and associated migration of earthquake activity within the rift.

  6. Fault-slip accumulation in an active rift over thousands to millions of years and the importance of paleoearthquake sampling

    NASA Astrophysics Data System (ADS)

    Mouslopoulou, Vasiliki; Nicol, Andrew; Walsh, John J.; Begg, John G.; Townsend, Dougal B.; Hristopulos, Dionissios T.

    2012-03-01

    The catastrophic earthquakes that recently (September 4th, 2010 and February 22nd, 2011) hit Christchurch, New Zealand, show that active faults, capable of generating large-magnitude earthquakes, can be hidden beneath the Earth's surface. In this article we combine near-surface paleoseismic data with deep (<5 km) onshore seismic-reflection lines to explore the growth of normal faults over short (<27 kyr) and long (>1 Ma) timescales in the Taranaki Rift, New Zealand. Our analysis shows that the integration of different timescale datasets provides a basis for identifying active faults not observed at the ground surface, estimating maximum fault-rupture lengths, inferring maximum short-term displacement rates and improving earthquake hazard assessment. We find that fault displacement rates become increasingly irregular (both faster and slower) on shorter timescales, leading to incomplete sampling of the active-fault population. Surface traces have been recognised for <50% of the active faults and along ≤50% of their lengths. The similarity of along-strike displacement profiles for short and long time intervals suggests that fault lengths and maximum single-event displacements have not changed over the last 3.6 Ma. Therefore, rate changes are likely to reflect temporal adjustments in earthquake recurrence intervals due to fault interactions and associated migration of earthquake activity within the rift.

  7. Global strike-slip fault distribution on Enceladus reveals mostly left-lateral faults

    NASA Astrophysics Data System (ADS)

    Martin, E. S.; Kattenhorn, S. A.

    2013-12-01

    Within the outer solar system, normal faults are a dominant tectonic feature; however, strike-slip faults have played a role in modifying the surfaces of many icy bodies, including Europa, Ganymede, and Enceladus. Large-scale tectonic deformation in icy shells develops in response to stresses caused by a range of mechanisms including polar wander, despinning, volume changes, orbital recession/decay, diurnal tides, and nonsynchronous rotation (NSR). Icy shells often preserve this record of tectonic deformation as patterns of fractures that can be used to identify the source of stress responsible for creating the patterns. Previously published work on Jupiter's moon Europa found that right-lateral strike-slip faults predominantly formed in the southern hemisphere and left-lateral strike-slip faults in the northern hemisphere. This pattern suggested they were formed in the past by stresses induced by diurnal tidal forcing, and were then rotated into their current longitudinal positions by NSR. We mapped the distribution of strike-slip faults on Enceladus and used kinematic indicators, including tailcracks and en echelon fractures, to determine their sense of slip. Tailcracks are secondary fractures that form as a result of concentrations of stress at the tips of slipping faults with geometric patterns dictated by the slip sense. A total of 31 strike-slip faults were identified, nine of which were right-lateral faults, all distributed in a seemingly random pattern across Enceladus's surface, in contrast to Europa. Additionally, there is a dearth of strike-slip faults within the tectonized terrains centered at 90°W and within the polar regions north and south of 60°N and 60°S, respectively. The lack of strike-slip faults in the north polar region may be explained, in part, by limited data coverage. The south polar terrain (SPT), characterized by the prominent tiger stripes and south polar dichotomy, yielded no discrete strike-slip faults. This does not suggest that

  8. Pushing the Limits of Geological Mapping Outside the Earth: 3D Modeling of Strike-Slip and Extensional Fault Systems in Meridiani Planum Region, Mars.

    NASA Astrophysics Data System (ADS)

    Vidal Royo, O.

    2014-12-01

    GIS and geological modeling software have radically changed the means by which geological mapping is produced, published and visualized. This type of software environment normally requires a spatially aware reference system to position data and interpretation, often referred as georeferenced data (i.e. geographic data referenced on the Earth). However, for this study we coin the term areoreferenced data (i.e. Mars-referenced "geographic" data). Thanks to the wealth of areoreferenced data made available by the NASA and the HiRise at University of Arizona it is now possible to carry out 3D areographic and areologic (i.e. related to the topography and geology of Mars, respectively) reconstructions in great detail. The present work benefits from the availability of software and areographic data, and presents the results of an areologic map and 3D model of the fault systems in the Meridiani Planum of Mars. The work has been carried out in Move™ (developed by Midland Valley Exploration), a geological modeling toolkit that allows for easy data loading in a wide range of formats as well as straightforward 2D/3D model building tools of geological bodies. Initial data consisted of Digital Terrain Model and orthoimages (NASA/JPL/University of Arizona/USGS). From these we have interpreted several structural domains: right-lateral strike-slip systems with associated releasing bends, which gave room to an extensional event causing a horizontal-axis rotation of the bedding. Bedding ranges from subhorizontal in the southern domain where strike-slip prevails to nearly 40º in the central and northern domains, where a more complex interaction between strike-slip and extensional faults is described. The stratigraphic sequence is mainly composed by moderately rounded well laminated basaltic sandstones (Squyres et al., 2004) in which a high component of sulfurs (e.g. sulfate anhydrate, hexahydrite, epsomite, gypsum) and salts (e.g. halite) has been described (Squyres et al., 2004

  9. Paleostress states at the south-western margin of the Central European Basin System — Application of fault-slip analysis to unravel a polyphase deformation pattern

    NASA Astrophysics Data System (ADS)

    Sippel, Judith; Scheck-Wenderoth, Magdalena; Reicherter, Klaus; Mazur, Stanislaw

    2009-05-01

    We analyse the deformation pattern along the south-western margin of the Central European Basin System (CEBS) where Upper Carboniferous-Mesozoic rocks are uplifted due to the Late Cretaceous basin inversion. The geometry of mesoscale faults and associated striae are used to calculate the stress state(s) responsible for the observed deformation. Each reduced stress tensor obtained comprises (i) the directions of the principal stress axes σ1, σ2, and σ3 ( σ1 ≥ σ2 ≥ σ3) and (ii) the ratio of principal stress differences R = ( σ2 - σ3) / ( σ1 - σ3). We present a stress inversion technique that allows each stress state inherent in a heterogeneous fault population to be identified by integrating the results of the PBT-Method [Turner, F.J., 1953. Nature and dynamic interpretation of deformation lamellae in calcite of three marbles. American Journal of Sciences, 251(4): 276-298; Sperner, B., Ratschbacher, L. and Ott, R., 1993. Fault-striae analysis: a Turbo Pascal program package for graphical presentation and reduced stress tensor calculation. Computers & Geosciences, 19: 1361-1388] and the Multiple Inverse Method [Yamaji, A., 2000. The multiple inverse method; a new technique to separate stresses from heterogeneous fault-slip data. Journal of Structural Geology, 22(4): 441-452]. This comprehensive approach not only facilitates the separation of complex data sets into homogeneous subsets but also guarantees that each stress state derived fulfils both the criteria of low-misfit angles (Wallace-Bott hypothesis) and high shear-to-normal-stress ratios (Mohr-Coulomb criterion). The reliability of our technique is confirmed by the fact that irrespective of (i) the number of fault-slip data from an outcrop, (ii) the number of subsets they represent and (iii) the proportion of newly formed and reactivated faults, we obtain consistent results from outcrops of variously aged rocks. This consistency concerns both calculated stress states as well as locally observed

  10. Estimating Fault Slip Rates and Deformation at Complex Strike-Slip Plate Boundaries

    NASA Astrophysics Data System (ADS)

    Thatcher, Wayne; Murray-Moraleda, Jessica

    2010-05-01

    initiation date of offset of geomorphic markers by faulting can introduce uncertainties much larger than quoted random errors. Second: Are rate estimates obtained by more than one geodetic or geologic method? For example, agreement between GPS and InSAR slip rate estimates on the Altyn Tagh and Haiyuan faults of Tibet make the geodetic estimates more reliable. Similarly, dating of multiple offset markers of differing age across these faults supports the consistency of the geologic rate estimates. Third: Is proposed rate change mechanism consistent with examples of changes in style and rate of deformation preserved in the geologic record? For example, temporal evolution of the multi-stranded San Andreas system during the past 5-10 Ma (Powell & Weldon 1992; Graymer et al. 2002) indicates activation and deactivation of different faults within the system accompanied by consequent changes in fault slip rate and/or creation of new crustal blocks. Fourth: Is there a quantitative analysis of mechanism proposed to explain rate change? Candidate mechanisms meriting quantitative analysis include (1) changes in frictional resistance of faults and creation of new fractures due to progressive rotation of irregularly shaped blocks, (2) episodic subduction of buoyant lithosphere, and (3) changes in the plate geometry (and so the forces acting) at major continent/ocean plate boundaries (e.g. Late Cenozoic migration of Mendocino triple junction off California). In most parts of southern California—for example, north of the San Andreas Big Bend and SE of Los Angeles--our block geometry closely resembles that assumed in previous studies (McCaffrey 2005 JGR; Meade & Hager 2005 JGR; Becker et al. 2005 GJI). In these regions GPS slip rates can be reliably estimated and values for individual faults generally agree from one study to another and are also consistent with geologic estimates. However, there is no consensus on block geometry in the Transverse Ranges, Los Angeles Basin and Central

  11. Frictional properties of the active San Andreas Fault at SAFOD: Implications for fault strength and slip behavior

    NASA Astrophysics Data System (ADS)

    Carpenter, B. M.; Saffer, D. M.; Marone, C.

    2015-07-01

    We present results from a comprehensive laboratory study of the frictional strength and constitutive properties for all three active strands of the San Andreas Fault penetrated in the San Andreas Observatory at Depth (SAFOD). The SAFOD borehole penetrated the Southwest Deforming Zone (SDZ), the Central Deforming Zone (CDZ), both of which are actively creeping, and the Northeast Boundary Fault (NBF). Our results include measurements of the frictional properties of cuttings and core samples recovered at depths of ~2.7 km. We find that materials from the two actively creeping faults exhibit low frictional strengths (μ = ~0.1), velocity-strengthening friction behavior, and near-zero or negative rates of frictional healing. Our experimental data set shows that the center of the CDZ is the weakest section of the San Andreas Fault, with μ = ~0.10. Fault weakness is highly localized and likely caused by abundant magnesium-rich clays. In contrast, serpentine from within the SDZ, and wall rock of both the SDZ and CDZ, exhibits velocity-weakening friction behavior and positive healing rates, consistent with nearby repeating microearthquakes. Finally, we document higher friction coefficients (μ > 0.4) and complex rate-dependent behavior for samples recovered across the NBF. In total, our data provide an integrated view of fault behavior for the three active fault strands encountered at SAFOD and offer a consistent explanation for observations of creep and microearthquakes along weak fault zones within a strong crust.

  12. Late Neogene slip transfer and extension within the curved Whisky Flat fault system central Walker Lane, west-central Nevada

    NASA Astrophysics Data System (ADS)

    Biholar, Alexander Kenneth Casian

    In Whisky Flat of west-central Nevada, northwest-striking faults in the Walker Lane curve to east-northeast orientations at the northern limits of the Mina deflection. This curve in strike results in the formation of ˜685 m deep depression bounded by north-south convex to the east range-front faults that at the apex of fault curvature are bisected at a high angle by a structural stepover. We use the vertical offset of a late Miocene erosional surface mapped in the highlands and inferred from gravity depth inversion in the basin to measure the magnitude of displacement on faults. A N65°W extensional axis determined through fault-slip inversion is used to constrain the direction in displacement models. Through the use of a forward rectilinear displacement model, we document that the complex array of faults is capable of developing with broadly contemporaneous displacements on all structures since the opening of the basin during the Pliocene.

  13. Extreme multi-millennial slip rate variations on the Garlock fault, California: Strain super-cycles, potentially time-variable fault strength, and implications for system-level earthquake occurrence

    NASA Astrophysics Data System (ADS)

    Dolan, James F.; McAuliffe, Lee J.; Rhodes, Edward J.; McGill, Sally F.; Zinke, Robert

    2016-07-01

    Pronounced variations in fault slip rate revealed by new measurements along the Garlock fault have basic implications for understanding how faults store and release strain energy in large earthquakes. Specifically, dating of a series of 26.0+3.5/-2.5 m fault offsets with a newly developed infrared-stimulated luminescence method shows that the fault was slipping at >14.0+2.2/-1.8 mm /yr, approximately twice as fast as the long-term average rate, during a previously documented cluster of four earthquakes 0.5-2.0 ka. This elevated late Holocene rate must be balanced by periods of slow or no slip such as that during the ca. 3300-yr-long seismic lull preceding the cluster. Moreover, whereas a comparison of paleoseismic data and stress modeling results suggests that individual Garlock earthquakes may be triggered by periods of rapid San Andreas fault slip or very large-slip events, the "on-off" behavior of the Garlock suggests a longer-term mechanism that may involve changes in the rate of elastic strain accumulation on the fault over millennial time scales. This inference is consistent with most models of the geodetic velocity field, which yield slip-deficit rates that are much slower than the average latest Pleistocene-early Holocene (post-8-13 ka) Garlock slip rate of 6.5 ± 1.5 mm /yr. These observations indicate the occurrence of millennia-long strain "super-cycles" on the Garlock fault that may be associated with temporal changes in elastic strain accumulation rate, which may in turn be controlled by variations in relative strength of the various faults in the Garlock-San Andreas-Eastern California Shear Zone fault system and/or changes in relative plate motion rates.

  14. Constraining the slip distribution and fault geometry of the Mw 7.9, 3 November 2002, Denali fault earthquake with Interferometric Synthetic Aperture Radar and Global Positioning System data

    USGS Publications Warehouse

    Wright, Tim J.; Lu, Zhiming; Wicks, C.

    2004-01-01

    The Mw 7.9, Denali fault earthquake (DFE) is the largest continental strike-slip earthquake to occur since the development of Interferometric Synthetic Aperture Radar (InSAR). We use five interferograms, constructed using radar images from the Canadian Radarsat-1 satellite, to map the surface deformation at the western end of the fault rupture. Additional geodetic data are provided by displacements observed at 40 campaign and continuous Global Positioning System (GPS) sites. We use the data to determine the geometry of the Susitna Glacier fault, thrusting on which initiated the DFE, and to determine a slip model for the entire event that is consistent with both the InSAR and GPS data. We find there was an average of 7.3 ± 0.4 m slip on the Susitna Glacier fault, between 1 and 9.5 km depth on a 29 km long fault that dips north at 41 ± 0.7° and has a surface projection close to the mapped rupture. On the Denali fault, a simple model with large slip patches finds a maximum of 8.7 ± 0.7 m of slip between the surface and 14.3 ± 0.2 km depth. A more complex distributed slip model finds a peak of 12.5 ± 0.8 m in the upper 4 km, significantly higher than the observed surface slip. We estimate a geodetic moment of 670 ± 10 × 1018 N m (Mw 7.9), consistent with seismic estimates. Lack of preseismic data resulted in an absence of InSAR coverage for the eastern half of the DFE rupture. A dedicated geodetic InSAR mission could obviate coverage problems in the future.

  15. Inorganic glass ceramic slip rings

    NASA Technical Reports Server (NTRS)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  16. Thermo-poro-mechanics of chemically active creeping faults: 3. The role of serpentinite in episodic tremor and slip sequences, and transition to chaos

    NASA Astrophysics Data System (ADS)

    Poulet, T.; Veveakis, E.; Regenauer-Lieb, K.; Yuen, D. A.

    2014-06-01

    During the last decade, knowledge over episodic tremor and slip (ETS) events has increased dramatically owing to the widespread installation of GPS and seismic networks. The most puzzling observations are (i) the periodic nature of slow seismic events, (ii) their localization at intermediate depths (estimated 15-40 km), and (iii) the origin of the nonvolcanic fluids that are responsible for the tremor activity. We reconcile these observations using a first principles approach relying on physics, continuum mechanics, and chemistry of serpentinite in the megathrust interface. The approach reproduces the GPS sequences of 17 years of recording in Cascadia, North America, as well as over 10 years in the Hikurangi Trench of New Zealand. We show that strongly endothermic reactions, such as serpentinite dehydration, are required for ETS events. We report that in this tectonic setting, it is its chemical reaction kinetics, not the low friction, that marks serpentinite as a key mineral for stable, self-sustained oscillations. We find that the subduction zone instabilities are driven from the ductile realm rather than the brittle cover. Even when earthquakes in the cover perturb the oscillator, it relaxes to its fundamental mode. Such a transition from stable oscillations to chaos is witnessed in the ETS signal of NZ following the M6.8, 2007 seismic event, which triggered a secondary mode of oscillations lasting for a few years. We consequently suggest that the rich dynamics of ductile modes of failure may be used to decipher the chaotic time sequences underpinning seismic events.

  17. Quasi-static versus dynamic triggering of fault slip

    NASA Astrophysics Data System (ADS)

    Wu, W.

    2013-12-01

    The quasi-static triggering of fault slip has long been recognized as a mechanism of earthquakes. The dynamic triggering of fault slip is associated with earthquake aftershocks and man-made geological hazards, such as rock collapse in underground excavations and induced seismicity in geothermal productions. The objective of this study is to experimentally investigate the differences between quasi-static and dynamic triggering of fault slip. A direct-shear configuration (Fig. 1) is developed to simulate fault slip, which consists of an incident norite plate (1000 × 120 × 30 mm) and a transverse norite plate (500 × 80 × 30 mm). A quartz sand layer is sandwiched between the incident and transverse plates to simulate a granular fault zone. A servo-controlled quasi-static loading system induces the quasi-static triggering of fault slip, and a dynamic loading system containing two parallel compressed springs instantaneously launches a striker norite plate (100 × 120 × 30 mm) to induce an incident P-wave (a half-wavelength of 750 mm). The P-wave propagates in the incident plate and causes the dynamic triggering of fault slip. The dynamic triggering of fault slip is designed to be solely induced by the P-wave before wave reflection at the plate end. Both quasi-static and dynamic triggering induce non-uniform shear stress distribution along the fault zone. There is a shear stress at the trailing edge, which controls the fault slip, and a rebound stress at the leading edge, which is caused by a small moment. The fault slip is triggered when the maximum shear stress reaches a critical value at the trailing edge and is accompanied by shear stress drop. The quasi-static triggering of fault slip is unrecoverable and includes a main slip and a few short slips before and after the main slip. The dynamic triggering of fault slip can be partially recovered after the P-wave and consists of a few unrecovered slips. The duration of the dynamic triggering of fault slip is a few

  18. Solar cell activation system

    SciTech Connect

    Apelian, L.

    1983-07-05

    A system for activating solar cells involves the use of phosphorescent paint, the light from which is amplified by a thin magnifying lens and used to activate solar cells. In a typical system, a member painted with phosphorescent paint is mounted adjacent a thin magnifying lens which focuses the light on a predetermined array of sensitive cells such as selenium, cadmium or silicon, mounted on a plastic board. A one-sided mirror is mounted adjacent the cells to reflect the light back onto said cells for purposes of further intensification. The cells may be coupled to rechargeable batteries or used to directly power a small radio or watch.

  19. Fault slip controlled by stress path and fluid pressurization rate

    NASA Astrophysics Data System (ADS)

    French, Melodie E.; Zhu, Wenlu; Banker, Jeremy

    2016-05-01

    The practice of injecting fluids into the crust is linked to regional increases in seismicity. Increasing fluid pressure along preexisting faults is believed to enhance seismicity rates by reducing the shear stress required for slip, but the processes that cause faults to slip under conditions of fluid pressurization are poorly constrained. We use experimental rock deformation to investigate the controls of fluid pressurization and pressurization rates on fault slip style. We show that pore fluid pressurization is less effective that mechanical changes in fault normal stress at initiating accelerated slip events. Fluid pressurization enhances the total slip, slip velocity, and shear stress drop of events initiated by mechanical changes in normal stress, and these parameters are correlated with pressurization rate, but not the magnitude of fluid pressure. This result is consistent with field-scale observations and indicates that processes active at the pore network scale affect induced seismicity.

  20. Production Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Gallaway, Ann, Ed.

    This production systems guide provides teachers with learning activities for secondary students. Introductory materials include an instructional planning outline and worksheet, an outline of essential elements, domains and objectives, a course description, and a content outline. The guide contains 30 modules on the following topics: production…

  1. Communication Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Sutherland, Barbara, Ed.

    This communication systems guide provides teachers with learning activities for secondary students. Introductory materials include an instructional planning outline and worksheet, an outline of essential elements, a list of objectives, a course description, and a content outline. The guide contains 32 modules on the following topics: story…

  2. Coseismic and Early Post-Seismic Slip Distributions of the 2012 Emilia (Northern Italy) Seismic Sequence: New Insights in the Faults Activation and Resulting Stress Changes on Adjacent Faults

    NASA Astrophysics Data System (ADS)

    Cheloni, D.; Giuliani, R.; D'Agostino, N.; Mattone, M.; Bonano, M.; Fornaro, G.; Lanari, R.; Reale, D.

    2015-12-01

    The 2012 Emilia sequence (main shocks Mw 6.1 May 20 and Mw 5.9 May 29) ruptured two thrust segments of a ~E-W trending fault system of the buried Ferrara Arc, along a portion of the compressional system of the Apennines that had remained silent during past centuries. Here we use the rupture geometry constrained by the aftershocks and new geodetic data (levelling, InSAR and GPS measurements) to estimate an improved coseismic slip distribution of the two main events. In addition, we use post-seismic displacements, described and analyzed here for the first time, to infer a brand new post-seismic slip distribution of the May 29 event in terms of afterslip on the same coseismic plane. In particular, in this study we use a catalog of precisely relocated aftershocks to explore the different proposed geometries of the proposed thrust segments that have been published so far and estimate the coseismic and post-seismic slip distributions of the ruptured planes responsible for the two main seismic events from a joint inversion of the geodetic data.Joint inversion results revealed that the two earthquakes ruptured two distinct planar thrust faults, characterized by single main coseismic patches located around the centre of the rupture planes, in agreement with the seismological and geological information pointing out the Ferrara and the Mirandola thrust faults, as the causative structures of the May 20 and May 29 main shocks respectively.The preferred post-seismic slip distribution related to the 29 May event, yielded to a main patch of afterslip (equivalent to a Mw 5.6 event) located westward and up-dip of the main coseismic patch, suggesting that afterslip was triggered at the edges of the coseismic asperity. We then use these co- and post-seismic slip distribution models to calculate the stress changes on adjacent fault.

  3. Slow slip event within a gap between tremor and locked zones in the Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Takagi, Ryota; Obara, Kazushige; Maeda, Takuto

    2016-02-01

    We report on two small long-term slow slip events (SSEs) within a gap between tremor and locked zones in the Nankai subduction zone, southwest Japan. The SSEs were detected by subtracting the steady state component and postseismic effects of large earthquakes from long-term and high-density Global Navigation Satellite System data. Both SSEs occurred in adjacent regions of the Bungo channel following long-term SSEs in the Bungo channel in 2003 and 2010. The estimated slip was 1-5 cm/year that lasted at least 1-2 years after 2004 and 2011, partly accommodating plate convergence. As the low-frequency tremor in the downdip region is activated at the same time as the Bungo channel long-term SSE, a spatiotemporal correlation was observed between the detected SSEs and long-term tremor activity in the downdip region. This correlation indicates along-dip interaction of the slips on the subducting plate interface.

  4. Statistical Analysis of the Surface Slip Profiles and Slip Models for the 2008 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Lavallee, D.; Shao, G.; Ji, C.

    2009-12-01

    The 2008 Wenchuan earthquake provides a remarkable opportunity to study the statistical properties of slip profiles recorded at the surface. During the M 8 Wenchuan earthquake, the surface ruptured over 300 km along the Longmenshan fault system. The surface slip profiles have been measured along the fault for a distance of the order of 270 km without any significant change in the strike direction. Field investigations suggest that the earthquake generated a 240 km surface rupture along the Beichuan segment and 72 km surface rupture along the Guanxian segment. Maximum vertical and horizontal slip of 10 m and 4.9 m have been observed along the Beichuan fault. Measurements include the displacement parallel and perpendicular to the fault as well as the width of the rupture zone. However, the recorded earthquake slip profiles are irregularly sampled. Traditional algorithms used to compute the discrete Fourier transform are developed for data sampled at regularly spaced intervals. It should be noted that interpolating the slip profile over a regular grid is not appropriate when investigating the spectrum functional behavior or when computing the discrete Fourier transform. Interpolation introduces bias in the estimation of the Fourier transform that adds artificial correlation to the original data. To avoid this problem, we developed an algorithm to compute the Fourier transform of irregularly sampled data. It consists essentially in determining the coefficients that best fit the data to the Sine and Cosine functions at a given wave number. We compute the power spectrum of the slip profiles of the Wenchuan earthquakes. In addition, we also compute the power spectrum for the slip inversions computed for the Wenchuan earthquakes. To model the functional behavior of the spectrum curves, we consider two functions: the power law function and the von Karman function. For all the slip models, we compute the parameters of the power law function and the von Karman function that

  5. New geologic slip rates for the Agua Blanca Fault, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Gold, P. O.; Behr, W. M.; Fletcher, J. M.; Hinojosa-Corona, A.; Rockwell, T. K.

    2015-12-01

    Within the southern San Andreas transform plate boundary system, relatively little is known regarding active faulting in northern Baja California, Mexico, or offshore along the Inner Continental Borderland. The inner offshore system appears to be fed from the south by the Agua Blanca Fault (ABF), which strikes northwest across the Peninsular Ranges of northern Baja California. Therefore, the geologic slip rate for the ABF also provides a minimum slip rate estimate for the offshore system, which is connected to the north to faults in the Los Angeles region. Previous studies along the ABF determined slip rates of ~4-6 mm/yr (~10% of relative plate motion). However, these rates relied on imprecise age estimates and offset geomorphic features of a type that require these rates to be interpreted as minima, allowing for the possibility that the slip rate for the ABF may be greater. Although seismically quiescent, the surface trace of the ABF clearly reflects Holocene activity, and given its connectivity with the offshore fault system, more quantitative slip rates for the ABF are needed to better understand earthquake hazard for both US and Mexican coastal populations. Using newly acquired airborne LiDAR, we have mapped primary and secondary fault strands along the segmented western 70 km of the ABF. Minimal development has left the geomorphic record of surface slip remarkably well preserved, and we have identified abundant evidence meter to km scale right-lateral displacement, including new Late Quaternary slip rate sites. We verified potential reconstructions at each site during summer 2015 fieldwork, and selected an initial group of three high potential slip rate sites for detailed mapping and geochronologic analyses. Offset landforms, including fluvial terrace risers, alluvial fans, and incised channel fill deposits, record displacements of ~5-80 m, and based on minimal soil development, none appear older than early Holocene. To quantitatively constrain landform ages

  6. Slipping of the foot on the floor when pulling a pallet truck.

    PubMed

    Li, Kai Way; Chang, Chien-Chi; Chang, Wen-Ruey

    2008-11-01

    Workers pulling pallet trucks are likely to slip when pulling and stepping on a low-friction floor. This study investigated the slipping of male participants when pulling a pallet truck, walking backward, and stepping on either a dry, wet, or glycerol-contaminated vinyl surface. The weight of the load on the truck was either low (0 kg), medium (295 kg), or high (568 kg). A motion-tracking system was used to collect the three-dimensional coordinates of the markers on the shoes. It was found that subjects might slip either upon landing of the leading foot on the toe (slip I) or before taking off of the lagging foot on the heel (slip II). The results indicated that the slip distances for both types of slip were significantly affected by the load and surface conditions and their interactions. Micro-slips (slips between 0.1 and 3 cm) and midi-slips (slips between 3 and 10 cm) were more common in slip I than in slip II. On glycerol-contaminated surfaces, the probabilities of a slide, or a slip more than 10 cm, for both slips I and II were over 40%. The implications of the results were discussed. PMID:18222414

  7. ADASY (Active Daylighting System)

    NASA Astrophysics Data System (ADS)

    Vázquez-Moliní, Daniel; González-Montes, Mario; Fernández-Balbuena, Antonio Á.; Bernabéu, Eusebio; García-Botella, Ángel; García-Rodríguez, Lucas; Pohl, Wilfried

    2009-08-01

    The main objective of ADASY (Active Daylighting System) work is to design a façade static daylighting system oriented to office applications, mainly. The goal of the project is to save energy by guiding daylight into a building for lighting purpose. With this approach we can reduce the electrical load for artificial lighting, completing it with sustainable energy. The collector of the system is integrated on a vertical façade and its distribution guide is always horizontal inside of the false ceiling. ADASY is designed with a specific patent pending caption system, a modular light-guide and light extractor luminaire system. Special care has been put on the final cost of the system and its building integration purpose. The current ADASY configuration is able to illuminate 40 m2 area with a 300lx-400lx level in the mid time work hours; furthermore it has a good enough spatial uniformity distribution and a controlled glare. The data presented in this study are the result of simulation models and have been confirmed by a physical scaled prototype. ADASY's main advantages over regular illumination systems are: -Low maintenance; it has not mobile pieces and therefore it lasts for a long time and require little attention once installed. - No energy consumption; solar light continue working even if there has been a power outage. - High quality of light: the colour rendering of light is very high - Psychological benefits: People working with daylight get less stress and more comfort, increasing productivity. - Health benefits

  8. Subduction zone structures and slip behavior in megathrust

    NASA Astrophysics Data System (ADS)

    Kodaira, S.; Nakanishi, A.; Nakamura, Y.

    2014-12-01

    Earthquake, tsunami and geodetic data show that co-seismic slips of a large megathrust earthquakes do not uniformly propagate along a plate boundary. For example, a clear segmentation of slip zones of magnitude-8 class megathrust earthquakes are well recognized in the Nankai Trough. Moreover, a lateral variation of the slips are revealed even in one segment. In the Japan Trench, the most characteristic slip behavior of the 2011 Tohoku-oki earthquake is an extremely large slip reaching to the trench axis, but geodetic, tsunami or teleseismic show the slip was heterogeneous near the trench. In order to examine whether those complex slip distributions are attributed by any distinct structural factor, we have been carried out active-source seismic surveys in the subduction seismogenic. In the Nankai Trough, large-scale subducted seamounts, ridges and doming structure intruded in an overriding accretion wedge are imaged. Comparing co-seismic slip distribution of the 1944 Tonankai and the 1946 Nankai earthquakes with the seismic images, we concluded that those structures are key factors to control the slip distributions. In the central part of the Japan Trench area, we fund a rough basement geometry is overprinted on the horst-and-graben structure. Those complex geometry of basement cause a strong lateral variation of the thickness of subducting pelagic/hemi-pelagic sediment. Many geological studies suggest that properties of the plate-boundary sediment attribute the large slip near the trench. We therefore plan to acquire additional high-resolution seismic data in the entire Japan Trench in order to examine a role of incoming sediment on the large slip to the trench axis. In this presentation we present an overview of the structural factors controlling slips in megathrust earthquakes, including new data acquired in the Nankai Trough and Japan Trench.

  9. The variations of long time period slow slip events along the Ryukyu subduction zone

    NASA Astrophysics Data System (ADS)

    Tu, Y. T.; Heki, K.

    2014-12-01

    Slow slip events (SSEs) are a type of slow earthquakes that can be observed with Global Positioning System (GPS) networks in the world. Those events are detected on intensely coupled plate boundaries such as Cascadia subduction zone (Dragert et al., 2001), western North America, Mexico (Kostoglodov et al., 2003), Alaska (Ohta et al., 2007) and Tokai and Boso areas (Ozawa et al., 2002, 2003), central Japan and are considered to have relations to large subduction thrust earthquakes. However, in southwestern Ryukyu trench where most of researchers believe that it should be a decoupled plate boundary, SSEs recur regularly and are located at a patch that is as deep as 20 to 40 km (Heki and Kataoka, 2008). For comprehending the characteristics and time variations of SSEs in this area, the GEONET GPS data of 16 years are used in this study. During 1997 to 2014, more than thirty SSEs are identified near Hateruma Island, Ryukyu. The average recurrence interval is calculated to be 6.3 months and release seismic moment is Mw 6.6 on average. However, the values of recurrence interval are not invariable. From 1997 to 2002, interval period of SSEs is 7.5 months, but during 2002 to 2008, the interval period decreases suddenly to 5.5 months. After 2008, the value restores to 7.2 months again. Furthermore, the slip amount of SSEs in this area varies with time. From 1997 to 2002, the slip is 9.5 cm/year; and during 2002 to 2008, the value slightly increases to 10.5 cm/year. However, in 2008 to 2013, the slip drops to 6.6 cm/year, but accord to the trend of cumulative slip, the slip value would increase in 2014. Considering these data, we find the slip values increase conspicuously in 2002 and 2013. Coincidentally, one Mw 7.1 thrust earthquake occurred in 2002 and earthquake swarm activity started in the Okinawa trough approximately 50km north of the SSE patch. In 2013, another earthquake swarm activity occurred in nearly the same area as the 2002 activity. This suggests that the

  10. Is frictional healing slip-dependent?

    NASA Astrophysics Data System (ADS)

    Bhattacharya, P.; Rubin, A. M.; Ryan, K. L.; Riviere, J. V.; Marone, C.

    2015-12-01

    Frictional re-strengthening of bare rock surfaces at very low stresses and near zero slip rate, as observed in the laboratory, is traditionally interpreted as showing support for purely time-dependent healing as embodied in the Aging law. However, while slide-hold-slide experiments on bare surfaces do show an apparent (purely) time-dependent increase in the static friction upon reslide, we show that the stress minima attained during the preceding holds show a strong slip-dependence which contradict the Aging law. A velocity strengthening Slip law explains such data much better. We also show that, large velocity step decreases, which drive the system far below steady state just like long holds, clearly support the slip-dependent response of the Slip law over the time-dependent healing contained in the Aging law. But, while time-dependent healing has an intuitive physical picture in terms of growth of the 'real contact area' with time, it is more difficult to ascribe one to slip-dependent healing. Here, we explore the possibility that the slip-dependence arises out of an interplay between contact `quality' and `quantity' at the scale of the asperity contacts. First, to further study the slip-dependence of healing, we carry out large velocity step decreases and sequences of long slide-hold-slides on both bare rock and gouge. Secondly, to probe the micro-mechanical origins of healing, we complement our mechanical data with amplitudes and travel time data of ultrasonic P- and S- waves transmitted across the sliding interface. While ultrasonic P-wave transmissivity has been used as a proxy for 'real contact area' in friction experiments by Nagata et al. (2012, 2014) before, the simultaneous use of P- and S-phases in our experiments is designed specifically to probe contact rheology. Initial results show strong correlations between changes in friction, transmitted wave amplitudes and travel times in response to changes in slip rate. We also observe important differences

  11. Wall slip of bubbles in foams

    NASA Astrophysics Data System (ADS)

    Saugey, A.; Drenckhan, W.; Weaire, D.

    2006-05-01

    We present a computational analysis of the flow of liquid foam along a smooth wall, as encountered in the transport of foams in vessels and pipes. We concentrate on the slip of the bubbles at the wall and present some novel finite element calculations of this motion for the case of fully mobile gas/liquid interfaces. Our two-dimensional simulations provide for the first time the bubble shapes and entire flow field, giving detailed insight into the distribution of stresses and dissipation in the system. In particular, we investigate the relationship between the drag force and the slip velocity of the bubble, which for small slip velocities obeys power laws, as predicted by previous semianalytical treatments.

  12. Slip partitioning by elastoplastic propagation of oblique slip at depth.

    PubMed

    Bowman, David; King, Geoffrey; Tapponnier, Paul

    2003-05-16

    Oblique motion along tectonic boundaries is commonly partitioned into slip on faults with different senses of motion. The origin of slip partitioning is important to structural geology, tectonophysics, and earthquake mechanics. Partitioning can be explained by the upward elastoplastic propagation of oblique slip from a fault or shear zone at depth. The strain field ahead of the propagating fault separates into zones of predominantly normal, reverse, and strike-slip faulting. The model successfully predicts the distribution of fault types along parts of the San Andreas and Haiyuan faults. PMID:12750513

  13. Investigation of crystallographic slip in polycrystalline Fe{sub 3}Al using slip trace measurement and microtexture determination

    SciTech Connect

    Raabe, D.; Keichel, J.; Gottstein, G.

    1997-07-01

    An intermetallic Fe{sub 72}Al{sub 28} alloy (doped with Cr, Zr, Mo, and C) with an imperfectly ordered B2 crystal structure was rolled at 830--860 K to {epsilon} = 20%. To investigate crystallographic slip an etching technique was developed which allowed slip traces to be determined in grain interiors rather than at the sample surface. To derive the prevalent glide systems both the slip traces and the corresponding orientations were determined in grain scale. Three types of slip systems were identified, namely {l_brace}110{r_brace}<111>, {l_brace}112{r_brace}<111>, and {l_brace}123{r_brace}<111>. However, the slip traces produced by {l_brace}123{r_brace}<111> systems appeared wavy and were interpreted in terms of macroscopic or effective rather than crystallographic slip. The critical resolved shear stress ratio of the slip systems involved was fitted from experiment using a Relaxed Constraints Taylor model. The best correspondence between predicted and experimentally observed slip systems was attained for a critical resolver shear stress ratio of {tau}{sub {l_brace}110{r_brace}}/{tau}{sub {l_brace}112{r_brace}} = 1.05/1.0.

  14. Quantum phase slip noise

    NASA Astrophysics Data System (ADS)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2016-07-01

    Quantum phase slips (QPSs) generate voltage fluctuations in superconducting nanowires. Employing the Keldysh technique and making use of the phase-charge duality arguments, we develop a theory of QPS-induced voltage noise in such nanowires. We demonstrate that quantum tunneling of the magnetic flux quanta across the wire yields quantum shot noise which obeys Poisson statistics and is characterized by a power-law dependence of its spectrum SΩ on the external bias. In long wires, SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T →0 . The quantum coherent nature of QPS noise yields nonmonotonous dependence of SΩ on T at small Ω .

  15. Volcanism and aseismic slip in subduction zones

    SciTech Connect

    Acharya, H.

    1981-01-10

    The spatial and temporal relationship of volcanism to the occurrence of large earthquakes and convergent plate motion is examined. The number of volcanic eruptions per year in a convergent zone is found to be linearly related to the aseismic slip component of plate motion. If the aseismic slip rate is low (coupling between converging plates is strong), then the primary manifestation of tectonic activity is the occurrence of large earthquakes with only infrequent volcanic activity. If, however, the aseismic slip rate is high (coupling is weak), then there are few large earthquakes, and volcanism is the principal manifestation of tectonic activity. This model is consistent with the spatial distribution of large earthquakes and active volcanoes in the circum-Pacific area. It is tested by examining the extent of volcanic activity in the rupture zones of the 1952--1973 sequence of earthquakes in the Japan--Kurile Islands area. The number of volcanic euptions along these zones during the interval between large earthquakes is used to compute the aseismic slip rates for these segments, based on the relationship developed in this study. The aseismic slip rates so computed agree with those determined from the earthquake history of the area and rates of plate motion. The agreement suggests that in the interval between large earthquakes, the aseismic plate motion is manifested in a specific number of volcanic eruptions. Therefore in areas with adequate historial data it should be possible to use the model developed in this study to monitor volcanic eruptions for long-term prediction of large earthquakes.

  16. Neutron activation analysis system

    DOEpatents

    Taylor, M.C.; Rhodes, J.R.

    1973-12-25

    A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

  17. Slip distributions on active normal faults measured from LiDAR and field mapping of geomorphic offsets: an example from L'Aquila, Italy, and implications for modelling seismic moment release

    NASA Astrophysics Data System (ADS)

    Wilkinson, Maxwell; Roberts, Gerald P.; McCaffrey, Ken; Cowie, Patience A.; Faure Walker, Joanna P.; Papanikolaou, Ioannis; Phillips, Richard J.; Michetti, Alessandro Maria; Vittori, Eutizio; Gregory, Laura; Wedmore, Luke; Watson, Zoë K.

    2015-05-01

    Surface slip distributions for an active normal fault in central Italy have been measured using terrestrial laser scanning (TLS), in order to assess the impact of changes in fault orientation and kinematics when modelling subsurface slip distributions that control seismic moment release. The southeastern segment of the surface trace of the Campo Felice active normal fault near the city of L'Aquila was mapped and surveyed using techniques from structural geology and using TLS to define the vertical and horizontal offsets of geomorphic slopes since the last glacial maximum (15 ± 3 ka). The fault geometry and kinematics measured from 43 sites and throw/heave measurements from geomorphic offsets seen on 250 scarp profiles were analysed using a modification of the Kostrov equations to calculate the magnitudes and directions of horizontal principal strain-rates. The map trace of the studied fault is linear, except where a prominent bend has formed to link across a former left-stepping relay-zone. The dip of the fault and slip direction are constant across the bend. Throw-rates since 15 ± 3 ka decrease linearly from the fault centre to the tip, except in the location of the prominent bend where higher throw rates are recorded. Vertical coseismic offsets for two palaeo earthquake ruptures seen as fresh strips of rock at the base of the bedrock scarp also increase within the prominent bend. The principal strain-rate, calculated by combining strike, dip, slip-direction and post 15 ± 3 ka throw rate, decreases linearly from the fault centre towards the tip; the strain-rate does not increase across the prominent fault bend. The above shows that changes in fault strike, whilst having no effect on the principal horizontal strain-rate, can produce local maxima in throw-rates during single earthquakes that persist over the timescale of multiple earthquakes (15 ± 3 ka). Detailed geomorphological and structural characterisation of active faults is therefore a critical

  18. Universal behavior in ideal slip

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Smith, John R.

    1991-01-01

    The slip energies and stresses are computed for defect-free crystals of Ni, Cu, Ag, and Al using the many-atom approach. A simple analytical expression for the slip energies is obtained, leading to a universal form for slip, with the energy scaled by the surface energy and displacement scaled by the lattice constant. Maximum stresses are found to be somewhat larger than but comparable with experimentally determined maximum whisker strengths.

  19. Vein attribute scaling in strike-slip and extensional fault damage zones affecting the platform carbonates in the Jabal Qusaybah anticline, Salakh Arc, Oman

    NASA Astrophysics Data System (ADS)

    Clemenzi, Luca; Balsamo, Fabrizio; Storti, Fabrizio; Solum, John; Taberner, Conxita; Tueckmantel, Christian

    2015-04-01

    Understanding factors that determine deformation intensity and vein attributes in fault damage zones is important to predict fracture patterns and fault system permeability in the subsurface. In this contribution we present a new dataset on vein attributes collected along 26 fault zones (extensional and strike-slip) developed in the Cretaceous platform carbonates of the Natih Formation during the growth of the Jabal Qusaybah anticline, in the foreland basin of the Oman Mountains. Extensional and strike slip fault zones accommodated comparable displacements (~0.1 up to ~100 m), but were active at different burial depths. Extensional fault zones developed at shallow burial depth (<1-2 km) during late-stage folding and strike-slip faulting, and are laterally restricted by sub-vertical strike-slip fault zones. Vein aperture (A), eight (H), and spacing (S) were measured in vertical sections by scanlines across 10 strike-slip and 16 extensional fault damage zones, and then statistically analyzed. In both strike-slip and extensional fault damage zones vein aperture and height generally increase approaching the master slip surfaces, while vein spacing decreases approaching them. Deformation intensity, calculated as vein H/S ratio per meter, exponentially increases moving from background host rock toward master slip surfaces. Furthermore, the mean vein H/S ratio calculated in each damage zone increases also with increasing fault displacement in extensional fault zones, whereas it remain almost constant in strike-slip fault zones. Different vein pattern evolutions in the two fault systems are due to the presence of sub-vertical strike-slip fault zones which provided mechanical barriers that hindered the lateral propagation of extensional fault zones. During extensional faulting, the vertical downthrown was not inhibited, thus resulting in a progressively higher deformation intensity in laterally-restricted, extensional fault damage zones.

  20. Mechanism of slip and twinning

    NASA Technical Reports Server (NTRS)

    Rastani, Mansur

    1992-01-01

    The objectives are to: (1) demonstrate the mechanisms of deformation in body centered cubic (BCC), face centered cubic (FCC), and hexagonal close-packed (HCP)-structure metals and alloys and in some ceramics as well; (2) examine the deformed microstructures (slip lines and twin boundaries) in different grains of metallic and ceramic specimens; and (3) study visually the deformed macrostructure (slip and twin bands) of metals and alloys. Some of the topics covered include: deformation behavior of materials, mechanisms of plastic deformation, slip bands, twin bands, ductile failure, intergranular fracture, shear failure, slip planes, crystal deformation, and dislocations in ceramics.

  1. Interplay of thrust, back-thrust, strike-slip and salt tectonics in a fold and thrust belt system: an example from Zakynthos Island, Greece

    NASA Astrophysics Data System (ADS)

    Zelilidis, A.; Papatheodorou, G.; Maravelis, A. G.; Christodoulou, D.; Tserolas, P.; Fakiris, E.; Dimas, X.; Georgiou, N.; Ferentinos, G.

    2016-01-01

    The southwestern flank of the Hellenic fold and thrust belt, situated along the southern edge of the Dinarides-Albanides-Hellenides continental convergent zone, was examined for reconstructing the tectonic deformation. This investigation presents an integrated study of onshore sedimentological and structural analyses, as well as offshore seismic lines, across the Pliocene-Pleistocene sedimentary succession in Zakynthos Island. Back-thrust faults, using the Triassic evaporites as decollement surface, during the Pliocene, and coeval diapiric intrusions formed three sub-basins on the hangingwall of the Kalamaki back-thrust fault. This interaction is responsible for the growth of the Skopos Mountain and the soft sediment deformation that formed synclines and slumps, respectively. Back-thrust and strike-slip faults were active during the early Pleistocene, and diapiric intrusions modified the bathymetry on the sea floor, giving rise to slumps and recumbent folds. At least five events of synsedimentary diapiric intrusions have been recognized and are marked by five slump horizons. During the Holocene, the diapiric intrusions between the Kalamaki back-thrust and the Vrachionas anticline could be either related to normal faults or gravitationally driven.

  2. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    USGS Publications Warehouse

    Prentice, Carol S.; Rizza, M.; Ritz, J.F.; Baucher, R.; Vassallo, R.; Mahan, S.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is∼1 mm yr–1 along the WIB and EIB segments and∼0.5 mm yr–1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78–7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of∼2500

  3. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    USGS Publications Warehouse

    Rizza, M.; Ritz, J.-F.; Braucher, R.; Vassallo, R.; Prentice, C.; Mahan, S.; McGill, S.; Chauvet, A.; Marco, S.; Todbileg, M.; Demberel, S.; Bourles, D.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans-particularly well preserved in the arid environment of the Gobi region-allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is ~1 mm yr-1 along the WIB and EIB segments and ~0.5 mm yr-1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78-7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of ~2500-5200 yr for past

  4. Slip distributions on active normal faults measured from Terrestrial Laser Scan (TLS) data and field mapping of geomorphic offsets: An example from L'Aquila, Italy, and implications for modeling seismic moment release

    NASA Astrophysics Data System (ADS)

    Wilkinson, M. W.; Roberts, G.; McCaffrey, K. J.; Cowie, P. A.; Faure Walker, J.; Papanikolaou, I.; Phillips, R. J.; Michetti, A.; Vittori, E.

    2012-12-01

    Surface slip distributions for an active normal fault in Italy have been measured using terrestrial laser scanning (TLS), concentrating on offsets developed since 15 ±3 ka and for 2 palaeoearthquake ruptures, in order to assess the impact of spatial changes in fault orientation and kinematics on sub-surface slip distributions that control seismic moment release. The southeastern half of the surface trace of the Campo Felice active normal fault near the city of L'Aquila, central Italy, was scanned with TLS to define the vertical and horizontal offsets of geomorphic slopes that formed during the last glacial maximum (15 ±3 ka) from the center of the fault to its southeastern tip. Field measurements were made to define the strike and dip of the fault plane and plunge and plunge direction of the slip vector from striations on slickensides. Throw measurements from 250 TLS-derived scarp profiles were analyzed using the crossint cross section interpretation program developed by the authors specifically for this study. Field data of fault kinematics from 43 sites were combined with the TLS-derived throw measurements using a modification of the Kostrov equations to calculate the magnitude and directions of the horizontal principle strain-rates. The studied 5 km long portion of the fault has an overall strike of 140°, but has a prominent bend where the strike is 100-140°, where the fault has linked across a former left-stepping relay-zone which had an along strike length of ~600 m and across strike width of ~300 m. Throw-rates defined by TLS-derived profiles across a 15 ±3 ka bedrock fault scarp decrease linearly from 0.95 ±0.025 mm/yr at the fault center through 0.5 ±0.025 mm/yr to zero at the fault tip, except in the position of the prominent bend where throws rates increase by 0.15 ±0.025 mm/yr over a distance of ~1 km. The vertical co-seismic offsets averaged between two palaeoearthquake ruptures that manifest themselves as fresh stripes of rock at the base of

  5. European Neutron Activation System.

    2013-01-11

    Version 03 EASY-2010 (European Activation System) consists of a wide range of codes, data and documentation all aimed at satisfying the objective of calculating the response of materials irradiated in a neutron flux. The main difference from the previous version is the upper energy limit, which has increased from 20 to 60 MeV. It is designed to investigate both fusion devices and accelerator based materials test facilities that will act as intense sources of high-energymore » neutrons causing significant activation of the surrounding materials. The very general nature of the calculational method and the data libraries means that it is applicable (with some reservations) to all situations (e.g. fission reactors or neutron sources) where materials are exposed to neutrons below 60 MeV. EASY can be divided into two parts: data and code development tools and user tools and data. The former are required to develop the latter, but EASY users only need to be able to use the inventory code FISPACT and be aware of the contents of the EAF library (the data source). The complete EASY package contains the FISPACT-2007 inventory code, the EAF-2003, EAF-2005, EAF-2007 and EAF-2010 libraries, and the EASY User Interface for the Window version. The activation package EASY-2010 is the result of significant development to extend the upper energy range from 20 to 60 MeV so that it is capable of being used for IFMIF calculations. The EAF-2010 library contains 66,256 reactions, almost five times more than in EAF-2003 (12,617). Deuteron-induced and proton-induced cross section libraries are also included, and can be used with EASY to enable calculations of the activation due to deuterons and proton [2].« less

  6. Late Quaternary slip rate of the Batang Fault and its strain partitioning role in Yushu area, central Tibet

    NASA Astrophysics Data System (ADS)

    Huang, Xuemeng; Du, Yi; He, Zhongtai; Ma, Baoqi; Xie, Furen

    2015-06-01

    The late Quaternary activity of Yushu segment is poorly understood compared with other segments within Ganzi-Yushu Fault system. We focused on the Batang Fault, a major branch fault of the Yushu segment. Interpretation of remote sensing images and field investigations reveals that this fault has a clear geomorphic expression which is characterized by prominent fault escarpment and systematically offset gullies, fluvial terraces and alluvial fans along strike. Morphotectonic mapping, combined with optically stimulated luminescence (OSL) and radiocarbon (14C) data, suggest that the Batang Fault is a late Holocene active left-lateral strike-slip fault, along with some reverse component. The average left-lateral slip rate of this fault is 2-4 mm/yr and vertical slip rate is 0.2-0.6 mm/yr since Late Pleistocene. Comparison with the slip rates of other faults within the Ganzi-Yushu Fault system demonstrates that the Batang Fault partitioned nearly a third of the strike slip deformation within Yushu segment. This study provides insights into the reasons why the Yushu Fault is relatively less active when compared with other segments within Ganzi-Yushu Fault system and is crucial to the seismic hazard assessment in Yushu area especially after the occurrence of 2010 Ms 7.1 Yushu earthquake.

  7. Are non-slip socks really 'non-slip'? An analysis of slip resistance

    PubMed Central

    Chari, Satyan; Haines, Terrence; Varghese, Paul; Economidis, Alyssia

    2009-01-01

    Background Non-slip socks have been suggested as a means of preventing accidental falls due to slips. This study compared the relative slip resistance of commercially available non-slip socks with other foot conditions, namely bare feet, compression stockings and conventional socks, in order to determine any traction benefit. Methods Phase one involved slip resistance testing of two commercially available non-slip socks and one compression-stocking sample through an independent blinded materials testing laboratory using a Wet Pendulum Test. Phase two of the study involved in-situ testing among healthy adult subjects (n = 3). Subjects stood unsupported on a variable angle, inclined platform topped with hospital grade vinyl, in a range of foot conditions (bare feet, non-slip socks, conventional socks and compression stockings). Inclination was increased incrementally for each condition until slippage of any magnitude was detected. The platform angle was monitored using a spatial orientation tracking sensor and slippage point was recorded on video. Results Phase one results generated through Wet Pendulum Test suggested that non-slip socks did not offer better traction than compression stockings. However, in phase two, slippage in compression stockings was detected at the lowest angles across all participants. Amongst the foot conditions tested, barefoot conditions produced the highest slip angles for all participants indicating that this foot condition provided the highest slip resistance. Conclusion It is evident that bare feet provide better slip resistance than non-slip socks and therefore might represent a safer foot condition. This study did not explore whether traction provided by bare feet was comparable to 'optimal' footwear such as shoes. However, previous studies have associated barefoot mobilisation with increased falls. Therefore, it is suggested that all patients continue to be encouraged to mobilise in appropriate, well-fitting shoes whilst in hospital

  8. A phase-field approach to no-slip boundary conditions in dissipative particle dynamics and other particle models for fluid flow in geometrically complex confined systems.

    PubMed

    Xu, Zhijie; Meakin, Paul

    2009-06-21

    Dissipative particle dynamics (DPD) is an effective mesoscopic particle model with a lower computational cost than molecular dynamics because of the soft potentials that it employs. However, the soft potential is not strong enough to prevent the DPD particles that are used to represent the fluid from penetrating solid boundaries represented by stationary DPD particles. A phase-field variable, phi(x,t), is used to indicate the phase at point x and time t, with a smooth transition from -1 (phase 1) to +1 (phase 2) across the interface. We describe an efficient implementation of no-slip boundary conditions in DPD models that combines solid-liquid particle-particle interactions with reflection at a sharp boundary located with subgrid scale accuracy using the phase field. This approach can be used for arbitrarily complex flow geometries and other similar particle models (such as smoothed particle hydrodynamics), and the validity of the model is demonstrated by DPD simulations of flow in confined systems with various geometries. PMID:19548707

  9. Temporal slip rate variability in the Lower Rhine Embayment, Northwest Europe

    NASA Astrophysics Data System (ADS)

    Gold, Ryan; Kuebler, Simon; Friedrich, Anke

    2016-04-01

    Low strain regions may be characterized by long periods of seismic quiescence, punctuated by periods of clustered earthquake activity. This type of non-periodic recurrence behavior challenges accurate seismic hazard analysis. The Lower Rhine Embayment in the German-Belgium-Netherland border region presents a unique opportunity to characterize the long-term record of faulting to evaluate the periodicity of earthquake occurrence in a low strain region. The Lower Rhine Embayment is covered by a high-resolution record of Quaternary terraces associated with the Rhine and Maas (Meuse) Rivers and their tributaries. These terraces are cut by numerous NW-trending faults and record cumulative displacements that exceed 100 m in numerous locations. In this study, we exploit this rich record of faulted fluvial terraces and find convincing evidence for temporally varying rates of Quaternary fault movement across the Lower Rhine Embayment. First, we document a significant increase in vertical fault slip rates since 700 ka, compared to the average slip rate since the start of the Quaternary using the top and base of the Main Terrace, respectively. Increases in slip rate exceed 500% along many of the faults, including the Swist/Erft, Stockheim, Viersen, Sandgewand, and Kirspenich fault systems. This increase in fault slip rate corresponds to a regional period of increased tectonic uplift of the Rhenish Massif, increased volcanism in Eifel, and incision of the Rhine River. In a second and related analysis, we synthesize terrace offset and age information from the Feldbiss fault system along the western boundary of the Lower Rhine Embayment, which transects a flight of Quaternary terraces associated with the Mass river. This analysis reveals evidence for secular variation in slip rate. In particular, we identify two periods of higher slip rate (800-400 ka and 130-100 ka), where fault slip rate exceeds the longer-term average slip rate of 0.04-0.05 mm/yr by as much as a factor of two

  10. A Novel Algorithm for Cycle Slip Detection and Repair

    NASA Astrophysics Data System (ADS)

    Sezen, U.; Arikan, F.

    2012-04-01

    Accurate and reliable estimation of ionospheric parameters are very important for correct functioning of communication, navigation and positioning satellite systems. In recent years, dual-frequency GPS receivers are widely used for estimation of Total Electron Content (TEC), which is defined as the line integral of the electron density along a ray path. Since both electron density and TEC are functions of solar, geomagnetic, gravitational and seismic activity, any disturbance along the ray path can be detected using GPS receiver observables. It is observed that, with the development of recent sophisticated receivers, disruptions due to the receiver antenna, hardware or outside obstructions are minimized. Most of the observed sudden disturbances are signal phase lock losses due to ionosphere. These sudden phase shifts are named as cycle slips and if not corrected, they may lead to positioning errors or incorrect TEC estimates. There are many methods in the literature that deal with cycle slips and their repairs, yet these methods are not matured to detect all kinds of cycle slips. Most algorithms require double differencing, and/or complicated Kalman Filters, Wavelet transforms, Neural Network models, and integration of external INS systems. In this study, we propose a fast and efficient algorithm for identifying the cycle slips on individual observables, classifying them for future investigations and finally repairing them for more accurate and reliable TEC estimates. The algorithm traces the pseudorange and phase observables and computes the geometry free combinations of L4 and P4. The sudden disturbances on L1, L2, P1, C1 and P2 are classified and noted for further use. Most of the cases, the disruptions are on phase observables, yet for a few occasions, a sudden disturbance is also observed on pseudorange observables. The algorithm, then, checks the epoch section where P4 exists continually. When a disruption on L1 or L2 occurs, it becomes evident on L4. When P4

  11. Rock mechanics. Superplastic nanofibrous slip zones control seismogenic fault friction.

    PubMed

    Verberne, Berend A; Plümper, Oliver; de Winter, D A Matthijs; Spiers, Christopher J

    2014-12-12

    Understanding the internal mechanisms controlling fault friction is crucial for understanding seismogenic slip on active faults. Displacement in such fault zones is frequently localized on highly reflective (mirrorlike) slip surfaces, coated with thin films of nanogranular fault rock. We show that mirror-slip surfaces developed in experimentally simulated calcite faults consist of aligned nanogranular chains or fibers that are ductile at room conditions. These microstructures and associated frictional data suggest a fault-slip mechanism resembling classical Ashby-Verrall superplasticity, capable of producing unstable fault slip. Diffusive mass transfer in nanocrystalline calcite gouge is shown to be fast enough for this mechanism to control seismogenesis in limestone terrains. With nanogranular fault surfaces becoming increasingly recognized in crustal faults, the proposed mechanism may be generally relevant to crustal seismogenesis. PMID:25504714

  12. Synchronous changes in the seismicity rate and ocean-bottom hydrostatic pressures along the Nankai trough: A possible slow slip event detected by the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET)

    NASA Astrophysics Data System (ADS)

    Suzuki, Kensuke; Nakano, Masaru; Takahashi, Narumi; Hori, Takane; Kamiya, Shinichiro; Araki, Eiichiro; Nakata, Ryoko; Kaneda, Yoshiyuki

    2016-06-01

    We detected long-term hydrostatic pressure changes at ocean-bottom stations of the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) along the Nankai trough, off southwestern Japan. We detected these changes after removing the contributions of ocean mass variations and sensor drift from the records. In addition, we detected a decrease in the background seismicity rate of a nearby earthquake cluster that was synchronous with the hydrostatic pressure changes. We interpreted these observed hydrostatic pressure changes to reflect vertical deformation of the ocean floor of 3-8 cm, and we consider the cause of the seafloor crustal deformation to be a slow slip event (SSE) beneath the stations. Because the pressure changes were observed at stations with distances less than 20 km to each other, we inferred that the SSE occurred in the shallow part of the sedimentary wedge, such as on a splay fault system. The synchronous observation of an SSE and a seismicity rate change suggests that both were triggered by a change in the regional stress that may be associated with stress accumulation and release processes occurring along the Nankai trough. These data show that continuous and careful monitoring of crustal activities by DONET stations provides an effective way to detect seismic and geodetic signals related to the occurrence of megathrust or other types of large earthquakes.

  13. Hydrodynamic slip length as a surface property.

    PubMed

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G P

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems. PMID:26986407

  14. Hydrodynamic slip length as a surface property

    NASA Astrophysics Data System (ADS)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.

  15. TATA-binding protein and transcription factor IIB induce transcript slipping during early transcription by RNA polymerase II.

    PubMed

    Gilman, Benjamin; Drullinger, Linda F; Kugel, Jennifer F; Goodrich, James A

    2009-04-01

    To better understand the mechanism of steps in early transcription by RNA polymerase II (pol II), we investigated the molecular determinants of transcript slipping within complexes assembled on promoters containing a pre-melted transcription bubble from -9 to +3. Transcript slippage occurs when an RNA transcript contains a repetitive sequence that allows the transcript to slip back and pair with the template strand of the DNA at a new register before transcription continues. We established the contributions of individual transcription factors, DNA elements, and RNA length to slipping on a heteroduplex template using a highly purified human pol II transcription system. We found that transcripts slip at a very defined point in the transcription reaction, after pol II completes phosphodiester bond synthesis at register +5. This point is set by the position of the polymerase active site on the DNA template, as opposed to the length of the transcript, as well as by a repetitive CUCU sequence that must occur from +2 to +5. Interestingly, slipping at this juncture is induced by TATA-binding protein and transcription factor IIB and requires a TATA box but not a transcription factor IIB recognition sequence. We propose a model in which transcribing complexes, upon completing phosphodiester bond synthesis at register +5, enter one of two branches in which they either complete productive synthesis of the transcript or undergo multiple rounds of transcript slipping. PMID:19193635

  16. Intentional Action and Action Slips.

    ERIC Educational Resources Information Center

    Heckhausen, Heinz; Beckmann, Jurgen

    1990-01-01

    An explanation of action slips is offered that examines controlled actions in the context of an intentional behavior theory. Actions are considered guided by mentally represented intentions, subdivided into goal intentions and contingent instrumental intentions. Action slips are categorized according to problem areas in the enactment of goal…

  17. Learning and Prediction of Slip from Visual Information

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Matthies, Larry; Helmick, Daniel; Perona, Pietro

    2007-01-01

    This paper presents an approach for slip prediction from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobility. Therefore, obtaining information about slip before entering such terrain can be very useful for better planning and avoiding these areas. To address this problem, terrain appearance and geometry information about map cells are correlated to the slip measured by the rover while traversing each cell. This relationship is learned from previous experience, so slip can be predicted remotely from visual information only. The proposed method consists of terrain type recognition and nonlinear regression modeling. The method has been implemented and tested offline on several off-road terrains including: soil, sand, gravel, and woodchips. The final slip prediction error is about 20%. The system is intended for improved navigation on steep slopes and rough terrain for Mars rovers.

  18. Principal Slip Zones in Carbonate: Microstructural Characterization and Implications for the Seismic Cycle

    NASA Astrophysics Data System (ADS)

    Smith, Steven; Billi, Andrea; di Toro, Giulio

    2010-05-01

    Main shocks in central Italy, such as the L'Aquila Mw 6.3 earthquake on 6 April 2009, and associated foreshock and aftershock sequences, often nucleate within, and rupture through, carbonate-bearing rocks within the upper-crust. One way to understand the mechanical behaviour of such rocks during the passage of earthquake ruptures is to study the Principal Slip Zones (PSZs) of exhumed faults. The PSZs are thought to accommodate a majority of displacement during individual earthquake slip events, and potentially contain a rich variety of information about earthquake-related processes and, more generally, deformation mechanisms throughout the seismic cycle. At present, however, there are no reliable microstructural or geochemical indicators of seismic slip in carbonate rocks. We present detailed field and microstructural observations of the PSZs of large-displacement, seismically active normal fault zones in the central Apennines of Italy. The fault zones are exhumed from <3km depth and cut 3-5km thick sequences of platform limestone. Samples were collected from individual PSZs containing polished slip surfaces with both small (centimetres to metres) and large (metres to hundreds of metres) displacements, including the main PSZ that defines the active Quaternary fault scarp. Small displacement slipping zones are characterized by typical cataclastic fabrics, including angular grains cross-cut by brittle fractures, and a gradual decrease in grain-size towards the polished slip surface. In contrast, large-displacement slipping zones always contain a continuous, texturally-distinct layer up to 2-3mm in thickness that lies immediately beneath the polished slip surface. This layer is itself internally zoned; up to 6 distinct zones can be present, each between 200-300µm in thickness, and recognized on the basis of grain-size, colour, and textural variations. In some cases, the zones developed at the expense of one another. 100-200µm-thick, syn-tectonic calcite veins

  19. Role of Slip Mode on Stress Corrosion Cracking Behavior

    NASA Astrophysics Data System (ADS)

    Vasudevan, A. K.; Sadananda, K.

    2011-02-01

    In this article, we examine the effect of aging treatment and the role of planarity of slip on stress corrosion cracking (SCC) behavior in precipitation-hardened alloys. With aging, the slip mode can change from a planar slip in the underage (UA) to a wavy slip in the overage (OA) region. This, in turn, results in sharpening the crack tip in the UA compared to blunting in the OA condition. We propose that the planar slip enhances the stress concentration effects by making the alloys more susceptible to SCC. In addition, the planarity of slip enhances plateau velocities, reduces thresholds for SCC, and reduces component life. We show that the effect of slip planarity is somewhat similar to the effects of mechanically induced stress concentrations such as due to the presence of sharp notches. Aging treatment also causes variations in the matrix and grain boundary (GB) microstructures, along with typical mechanical and SCC properties. These properties include yield stress, work hardening rate, fracture toughness K IC , thresholds K Iscc, and steady-state plateau velocity ( da/ dt). The SCC data for a wide range of ductile alloys including 7050, 7075, 5083, 5456 Al, MAR M steels, and solid solution copper-base alloys are collected from the literature. Our assertion is that slip mode and the resulting stress concentration are important factors in SCC behavior. This is further supported by similar observations in many other systems including some steels, Al alloys, and Cu alloys.

  20. Resonant slow fault slip in subduction zones forced by climatic load stress.

    PubMed

    Lowry, Anthony R

    2006-08-17

    Global Positioning System (GPS) measurements at subduction plate boundaries often record fault movements similar to earthquakes but much slower, occurring over timescales of approximately 1 week to approximately 1 year. These 'slow slip events' have been observed in Japan, Cascadia, Mexico, Alaska and New Zealand. The phenomenon is poorly understood, but several observations hint at the processes underlying slow slip. Although slip itself is silent, seismic instruments often record coincident low-amplitude tremor in a narrow (1-5 cycles per second) frequency range. Also, modelling of GPS data and estimates of tremor location indicate that slip focuses near the transition from unstable ('stick-slip') to stable friction at the deep limit of the earthquake-producing seismogenic zone. Perhaps most intriguingly, slow slip is periodic at several locations, with recurrence varying from 6 to 18 months depending on which subduction zone (or even segment) is examined. Here I show that such periodic slow fault slip may be a resonant response to climate-driven stress perturbations. Fault slip resonance helps to explain why slip events are periodic, why periods differ from place to place, and why slip focuses near the base of the seismogenic zone. Resonant slip should initiate within the rupture zone of future great earthquakes, suggesting that slow slip may illuminate fault properties that control earthquake slip. PMID:16915286

  1. Is there a "blind" strike-slip fault at the southern end of the San Jacinto Fault system?

    NASA Astrophysics Data System (ADS)

    Tymofyeyeva, E.; Fialko, Y. A.

    2015-12-01

    We have studied the interseismic deformation at the southern end of the San Jacinto fault system using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data. To complement the continuous GPS measurements from the PBO network, we have conducted campaign-style GPS surveys of 19 benchmarks along Highway 78 in the years 2012, 2013, and 2014. We processed the campaign GPS data using GAMIT to obtain horizontal velocities. The data show high velocity gradients East of the surface trace of the Coyote Creek Fault. We also processed InSAR data from the ascending and descending tracks of the ENVISAT mission between the years 2003 and 2010. The InSAR data were corrected for atmospheric artifacts using an iterative common point stacking method. We combined average velocities from different look angles to isolate the fault-parallel velocity field, and used fault-parallel velocities to compute strain rate. We filtered the data over a range of wavelengths prior to numerical differentiation, to reduce the effects of noise and to investigate both shallow and deep sources of deformation. At spatial wavelengths less than 2km the strain rate data show prominent anomalies along the San Andreas and Superstition Hills faults, where shallow creep has been documented by previous studies. Similar anomalies are also observed along parts of the Coyote Creek Fault, San Felipe Fault, and an unmapped southern continuation of the Clark strand of the San Jacinto Fault. At wavelengths on the order of 20km, we observe elevated strain rates concentrated east of the Coyote Creek Fault. The long-wavelength strain anomaly east of the Coyote Creek Fault, and the localized shallow creep observed in the short-wavelength strain rate data over the same area suggest that there may be a "blind" segment of the Clark Fault that accommodates a significant portion of the deformation on the southern end of the San Jacinto Fault.

  2. LiDAR-derived measurements of slip in the most recent ground-rupturing earthquakes along elements of the San Andreas fault system

    NASA Astrophysics Data System (ADS)

    Haddad, D. E.; Madden, C.; Salisbury, J. B.; Arrowsmith, R.; Weldon, R. J.

    2011-12-01

    Tectonically displaced geomorphic markers record the surface manifestation of earthquake-induced ground ruptures. Of particular interest to earthquake forecast models is the slip produced during the most recent ground-rupturing earthquake. High-resolution digital topography from light detection and ranging (LiDAR) is a powerful tool for measuring the most recent meter-scale slip along fault zones. We present surface slip measurements of recent ground-rupturing earthquakes along the Garlock, Owens Valley, Elsinore, and Blackwater-Calico fault zones. Fault scarp traces were mapped using LiDAR-derived digital elevation models (DEMs), local topographic gradient and relief maps, and aerial photography. An individual slip measurement was made for each offset feature by iteratively reconstructing the topography on either side of the fault and finding the best-matching vertically backslipped value. A goodness-of-fit approach was then used to calculate the best laterally backslipped displacement using a combination of vertical backslip, horizontal backslip, and topographic scaling. Along-strike, reach-averaged surface displacement distributions of the most recent earthquakes were then generated from the LiDAR-derived offsets and compared to published field-derived offset measurements. For the eastern section of the Garlock fault, our LiDAR-derived offsets compared well with those measured in the field and attained an R2 value of 0.88 with reach-averaged slip in the last event of 4.19 m ±0.69 m for the Searles Valley area (2.67 km reach), 4.65 m +0.76/-0.92 m for the Pilot Knob Valley area (24.68 km reach), and 3.45 m +0.82/-0.87 m for the Leach Lake and Avawatz Mountains areas (12.65 km reach), computed from a total of 129 offsets. Our results show that LiDAR-derived offset measurements compare well with field measurements in the comprehensive documentation of along-strike surface slip distributions of the most recent earthquake. Furthermore, our results demonstrate the

  3. Technology Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Brame, Ray; And Others

    This guide contains 43 modules of laboratory activities for technology education courses. Each module includes an instructor's resource sheet and the student laboratory activity. Instructor's resource sheets include some or all of the following elements: module number, course title, activity topic, estimated time, essential elements, objectives,…

  4. Phase Slips in Oscillatory Hair Bundles

    NASA Astrophysics Data System (ADS)

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production.

  5. Phase Slips in Oscillatory Hair Bundles

    PubMed Central

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-01-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  6. Phase slips in oscillatory hair bundles.

    PubMed

    Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

    2013-04-01

    Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production. PMID:25167040

  7. The role of thrust faulting in the formation of the eastern Alaska Range: Thermochronological constraints from the Susitna Glacier Thrust Fault region of the intracontinental strike-slip Denali Fault system

    NASA Astrophysics Data System (ADS)

    Riccio, Steven J.; Fitzgerald, Paul G.; Benowitz, Jeff A.; Roeske, Sarah M.

    2014-11-01

    Horizontal-slip along restraining bends of strike-slip faults is often partitioned into a vertical component via splay faults. The active Susitna Glacier Thrust Fault (SGTF), as shown by its initiation of the 2002 M7.9 Denali Fault earthquake, lies south of, and intersects the dextral strike-slip Denali Fault. Geochronology and thermochronology data from samples across the SGTF constrain the region's tectonic history and the role of thrusting in the formation of the eastern Alaska Range south of the Denali fault. U-Pb zircon ages indicate intrusion of plutons in the footwall (~57 Ma) and hanging wall (~98 Ma). These U-Pb zircon ages correlate to those from the Ruby Batholith/Kluane Terrane ~400 km east along the Denali Fault, supporting geologic correlations and hence constraints on long-term slip rates. 40Ar/39Ar mica and K-feldspar data from footwall and hanging wall samples (~54 to ~46 Ma) reflect cooling following magmatism and/or regional Eocene metamorphism related to ridge subduction. Combined with apatite fission track data (ages 43-28 Ma) and thermal models, both sides of the SGTF acted as a coherent block during the Eocene and early Oligocene. Contrasting apatite (U-Th)/He ages across the Susitna Glacier (~25 Ma footwall, ~15 Ma hanging wall) suggest initiation of faulting during the middle Miocene. Episodic cooling and exhumation is related to thrusting on known or hypothesized faults that progressively activate due to varying partition of strain along the Denali Fault associated with changing kinematics and plate interaction (Yakutat microplate collision, flat-slab subduction and relative plate motion change) at the southern Alaskan plate margin.

  8. The geometry of the active strike-slip El Tigre Fault, Precordillera of San Juan, Central-Western Argentina: integrating resistivity surveys with structural and geomorphological data

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Cortés, José M.; Rapalini, Augusto E.; Terrizzano, Carla M.

    2013-07-01

    The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central-Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.

  9. Strain Wave during the Transient Process of Fault Unstable Slip

    NASA Astrophysics Data System (ADS)

    Guo, L.; Liu, L.

    2011-12-01

    The "stick-slip" model was proposed as an important mechanism for shallow-focus earthquakes. The study on the transient process of fault unstable slip failure is helpful for understanding the earthquake preparatory process, the mechanism of energy released, the precursor and after shake effect. Double shear frictional experiments are conducted for simulating "stick-slip" phenomenon, and a specially designed multi-channel super dynamic strain field observation system is employed to acquire dada continuously with the sample rate of 3,400 samples/second. The rock deformation process can be recorded in detail, especially in the moment of unstable slip (The unstable slip duration is less than two second in experiments). The strain results from super dynamic strain field observation system show that multi-frequency components and tremendous amplitude fluctuation are included in strain signals along the fault. There are three clear phases during the unstable slip progress: pre-slip (phase I), high-frequency strain vibration (phase II) and strain regulating to stop (phase III). Each phase has its own characteristics on duration, strain rate, frequency, amplitude and energy release. There are strong fluctuations in duration of approximately 70ms in phase II. The frequency and maximum amplitude are 300-400Hz and 150~300μɛ respectively. Main strain energy release takes place at phase II, less than one-tenth of the total slip time, so that the whole course of dislocation or stress drop would not be taken as earthquake simply at least in laboratory. The phase characteristic of the strain wave is probably its inherent attribute of unstable slip process and independent of dynamical loading conditions. The elastic rebound phenomena, considered as one classic earthquake generation model, can be observed clearly by analyzing the rotation of the principal strain axis with strain variation. The rotated angle ranges from 5° to 15° typically. The value and location of precursor slip

  10. Active displacements recorded along major fault systems in caves (Eastern Alps, Austria)

    NASA Astrophysics Data System (ADS)

    Mitrovic, Ivanka; Plan, Lukas; Baron, Ivo; Grasemann, Bernhard

    2014-05-01

    Seismic data and GPS observations suggest that several major tectonic fault systems in the Eastern Alps are still active. However, direct geological evidences for recent movements along individual fault systems are rather scarce and limited to local observations in the Vienna Basin. Recently, tectonically damaged speleothems have been described from a cave close to the Salzach Ennstal Mariazeller Puchberger (SEMP) strike-slip fault, which accommodated the lateral extrusion of the Eastern Alps towards the Pannonian Basin. The project SPELEOTECT investigates the Quaternary tectonic activity and recent dynamics of micro-displacements along major fault systems of the Eastern Alps recorded in caves. The work focuses on cave passages, which have been displaced by active faulting and on speleothems, which have been damaged by fault movements. In order to bracket the tectonic events, flowstones, which have grown before and after the tectonic event are dated using the U-series disequilibrium method. For the reconstruction of the local stress field during (re)activation of the faults, the paleostress and the active stress field will be calculated from the fault-slip data of the recent micro-dislocations monitored with high-accuracy 3D crack-gauges. Cataclasites and fault gouges from sheared flowstones are investigated with high-resolution electron beam analytical techniques in order to characterize the microstructures caused by various deformation mechanisms within principal slip surfaces. Cathodoluminescense images are combined with electron backscattered diffraction maps in order to discriminating between fault displacements caused by seismic slip or aseismic creep. The major aim of SPELEOTECT is the record of a solid and broad data base of the paleoseismic record of the Eastern Alps for regional earthquake hazard assessment.

  11. A delicate balance of magmatic-tectonic interaction at Kilauea Volcano, Hawai`i, revealed from slow slip events

    USGS Publications Warehouse

    Montgomery-Brown, Emily; Poland, Michael; Miklius, Asta

    2015-01-01

    Eleven slow slip events (SSEs) have occurred on the southern flank of Kilauea Volcano, Hawai’i, since 1997 through 2014. We analyze this series of SSEs in the context of Kilauea’s magma system to assess whether or not there are interactions between these tectonic events and eruptive/intrusive activity. Over time, SSEs have increased in magnitude and become more regular, with interevent times averaging 2.44 ± 0.15 years since 2003. Two notable SSEs that impacted both the flank and the magmatic system occurred in 2007, when an intrusion and small eruption on the East Rift Zone were part of a feedback with a SSE and 2012, when slow slip induced 2.5 cm of East Rift Zone opening (but without any change in eruptive activity). A summit inflation event and surge in East Rift Zone lava effusion was associated with a SSE in 2005, but the inferred triggering relation is not clear due to a poorly constrained slip onset time. Our results demonstrate that slow slip along Kilauea’s décollement has the potential to trigger and be triggered by activity within the volcano’s magma system. Since only three of the SSEs have been associated with changes in magmatic activity within the summit and rift zones, both the décollement and magma system must be close to failure for triggering to occur.

  12. Geodetically derived fault slip distribution model for the May, 11th 2011 Lorca earthquake (SE, Spain)

    NASA Astrophysics Data System (ADS)

    Gonzalez, P. J.; Tiampo, K. F.; Palano, M.; Cannavò, F.; Fernandez, J.

    2011-12-01

    of the city of Lorca. The shallower character of the slip probably caused the relative intense ground acceleration recorded at the Lorca city (0.4g) and increased the building damages. We show that the Lorca earthquake was generated by a simple segment (6-8 km long) slightly dipping to the NW of the AMF system. This study also represents the first modern geodetically observed ground deformation signature due to seismic activity in the Iberian Peninsula.

  13. Reconstructing temporal variations in fault slip from footwall topography: An example from Saline Valley, California (Invited)

    NASA Astrophysics Data System (ADS)

    Kirby, E.; Regalla, C.; Ouimet, W. B.; Bierman, P. R.

    2010-12-01

    It is becoming increasingly apparent that many intra-plate fault systems exhibit significant variability their rates of displacement over timescales ranging from 104 - 106 yr. Whether such variability arises simply as a consequence of fault system evolution or whether it reflects temporal changes in the rate of loading in the deep crust remains a first-order question. Because most records of fault slip at these timescales rely on geomorphic markers, inherently ephemeral features in the landscape, characterizing the history of fault slip through time can be difficult and is usually limited to environments with high rates of sediment deposition. In erosional landscapes, however, changes in the throw rates of fault systems are expected to engender systematic changes in landscape topography as channels and hillslopes adjust to changes in relative base level. Here we combine quantitative analysis of stream profiles with measurements of erosion rate (using detrital inventories of 10Be in sediment) from footwall catchments in the Inyo Mountains, in eastern California, to recognize and place constraints on the timing and of a sustained acceleration in fault slip along the range-front fault system. The Inyo Mountains are the footwall block to an active fault system along the western margin of Saline Valley; relief between the range and valley floor averages ~3 km. Normal-oblique slip along the range-front fault is linked to strike-slip displacement on the Hunter Mountain fault. Estimates for the onset of slip along this system range from 2.8 - 4.0 Ma, implying average slip rates of 2.1 - 3.3 mm/yr. However, geodetic measures suggest modern slip rates reach or exceed ~4.5 mm/yr. Analysis of channel profiles draining the Inyo Range reveals pronounced knickpoints that separate relatively low-gradient headwater reaches from exceedingly steep lower reaches. Knickpoints are only present along channels that cross the range-front fault, are developed within a single lithology, and

  14. [Study on the compatibility of slip casting aluminous ceramic crowns

    PubMed

    Wan, Q B; Xue, M; You, L; Du, C S; Chao, Y L

    1997-03-01

    One of the key factors for a good slip casting aluminous ceramic crown is good compatibility between its core material and the veneering porcelain.The chemical and thermal compatibility of two slip casting aluminous ceramic crown systems(In-Ceram and GI-I) were investigated by means of SEM and EDAX,thermal shock tests were also performed to evaluate the crazing resistance.The results showed: the crazing resistance of In-Ceram was 158 degrees centigrade,and that of GI-I was degrees centigrade;there existed tightly bonded interfaces between the slip casting aluminous ceramic cores and the veneering porcelains in both of the two systems,where ion transferences were found.The results also suggested good compatibility of the two slip casting aluminous ceramic crown systems. PMID:15159959

  15. The late Quaternary slip history of the North Anatolian Fault, Turkey: Implications for the spatial and temporal behaviour of large strike-slip fault belts

    NASA Astrophysics Data System (ADS)

    Zabcı, Cengiz; Akyüz, H. Serdar; Sançar, Taylan; Güneç Kıyak, Nafiye

    2015-04-01

    The study of the spatial and temporal behaviour of active faults by estimating the geologic and geodetic slip rates is critical not only for assessing the seismic potential of these tectonic structures, but also for understanding their geodynamics. Geodetic data can provide detailed spatial coverage but represent a short time interval of a single earthquake cycle, while geologic rates are derived as average values for multiple events at spatially limited sites. In the complex tectonic setting of the eastern Mediterranean, the westward extrusion of the Anatolian scholle is mainly accommodated by two major tectonic structures, the North Anatolian (NASZ) and the East Anatolian (EASZ) shear zones, respectively forming the northern and eastern boundaries. The rate of deformation all along the North Anatolian Fault (NAF) is spatially well documented mainly by GPS and InSAR based geodetic studies during the last two decades. Furthermore, the number of the morphochronology-based geologic slip rate studies significantly increased, covering the different sections of this large strike slip fault for various time intervals. In this study, we do not only compile all previous geologic slip rate estimates, but we also present data for three new and two revised sites from central to the most eastern parts of the NAF in order to understand the spatial and temporal behaviour of this important fault system. The integrated dataset of geologic studies were classified into two groups to represent the central to eastern sections (Model I) and the western part (Model II). The geographical diversion between two models is about at the 31° E longitude, where the NAF bifurcates into two branches from this point toward west into the Marmara Region. To test any secular variation in fault's slip history, we used the Monte Carlo approach of Gold and Cowgill (2011). After the removal of rates, which do not account the near fault deformation or the existing parallel/sub-parallel faults, the Model

  16. Micro PIV measurement of slip flow on a hydrogel surface

    NASA Astrophysics Data System (ADS)

    Kikuchi, K.; Mochizuki, O.

    2014-06-01

    Slip flow on a hydrogel surface was investigated in order to clarify the effect of drag reduction on the aqueous surface of living things. Thin-film flow along the hydrogel surface was measured by using a micro PIV (particle image velocimetry) system for comparison with theoretical velocity distribution which satisfied the non-slip condition on a solid surface. The slip flow on the hydrogel was found to be related to the degree of swelling and molecular weight of the hydrogel materials. This shows the possibility of a reduction in wall shear stress as a result of the decrease in the velocity gradient near a wall surface.

  17. A possible restart of an interplate slow slip adjacent to the Tokai seismic gap in Japan

    NASA Astrophysics Data System (ADS)

    Ozawa, Shinzaburo; Tobita, Mikio; Yarai, Hiroshi

    2016-04-01

    The Tokai region of Japan is known to be a seismic gap area and is expected to be the source region of the anticipated Tokai earthquake with a moment magnitude of over 8. Interplate slow slip occurred from approximately 2001 and subsided in 2005 in the area adjacent to the source region of the expected Tokai earthquake. Eight years later, the Tokai region again revealed signs of a slow slip from early 2013. This is the first evidence based on a dense Global Positioning System network that Tokai long-term slow slips repeatedly occur. Two datasets with different detrending produce similar transient crustal deformation and aseismic slip models, supporting the occurrence of the Tokai slow slip. The center of the current Tokai slow slip is near Lake Hamana, south of the center of the previous Tokai slow slip. The estimated moments, which increase at a roughly constant rate, amount to that of an earthquake with a moment magnitude of 6.6. If the ongoing Tokai slow slip subsides soon, it will suggest that there are at least two different types of slow slip events in the Tokai long-term slow slip area: that is, a large slow slip with a moment magnitude of over 7 with undulating time evolution and a small one with a moment magnitude of around 6.6 with a roughly linear time evolution. Because the Tokai slow slip changes the stress state to one more favorable for the expected Tokai earthquake, intense monitoring is going on.

  18. Slip, Crystal Orientation, and Damage Evolution During Thermal Cycling in High-Strain Wafer-Level Chip-Scale Packages

    NASA Astrophysics Data System (ADS)

    Zhou, Bite; Zhou, Quan; Bieler, Thomas R.; Lee, Tae-kyu

    2015-03-01

    Wafer-level chip-scale package samples with pre-cross-sectioned edge rows were thermally cycled to study microstructure evolution and damage development. Electron backscattered diffraction (EBSD) and high-energy x-ray diffraction were used to obtain Sn grain orientations and the average coefficient of thermal expansion normal to the board in every joint of the package for samples in the as-fabricated and thermally cycled conditions. The results indicated a near-random distribution of joint orientation. Optical, scanning electron microscopy, and EBSD methods were used to characterize microstructure changes in pre-cross-sectioned samples due to thermal cycling. Slip trace analysis and Orientation Imaging Microscopy™ (OIM) show that slip systems with high Schmid factors (estimated global shear stress based on the package neutral point) are responsible for the observed microstructure evolution during thermal cycling, which provides information about slip systems that are more easily activated. Two joints were analyzed in detail to evaluate slip activity at different stages of their thermal history. The first case showed that a solidification twin grain boundary misorientation deviated from the twin relationship due to slip activity during thermal cycling, which can influence damage development and the path of crack propagation. The second case showed a new grain orientation developing due to gradual lattice rotation about the Sn [110] axis by a continuous recrystallization mechanism. This rotation was correlated with the operation of slip system . Small tin whiskers emerged from the initially polished chip interface and grew with increasing thermal cycles until a crack developed in the solder that relieved the stress. As the local stresses are not known experimentally, this analysis provides observations that can be compared with a crystal plasticity model simulation.

  19. Northward growth of the Qimen Tagh Range: A new model accounting for the Late Neogene strike-slip deformation of the SW Qaidam Basin

    NASA Astrophysics Data System (ADS)

    Cheng, Feng; Jolivet, Marc; Fu, Suotang; Zhang, Qiquan; Guan, Shuwei; Yu, Xiangjiang; Guo, Zhaojie

    2014-09-01

    Situated along the western termination of the Eastern Kunlun Mountains, the Qimen Tagh Range represents a key area to understand the Cenozoic basin-range interactions between the northeastern Tibetan Plateau and the Qaidam Basin. Within that region, several huge bow-like fault systems such as the Kunbei and Qimen Tagh fault systems accommodate the transpressive deformation but their kinematic evolution is still highly debated. Newly acquired seismic profiles and isopach maps of the Late Eocene sediments strongly suggest that the Kunbei fault system (consisting of the Kunbei, Arlar and Hongliuquan faults) in the southwestern Qadaim Basin was initially a left-lateral strike-slip fault system rather than a thrusting system. Growth strata indicate an Early Miocene onset age for this strike-slip deformation. However, earthquake focal mechanisms show that the present-day tectonic pattern of this fault system is dominated by NE-SW transpression. As for the Qimen Tagh fault system, numerous linear geomorphic features and fault scarps indicate that it was again a strike-slip fault system. Deformed sediments within the Adatan Valley prove that strike-slip motion prevailed during the Pleistocene, yet the present day deformation is marked by NE-SW transpression. Collectively, the Kunbei and Qimen Tagh fault systems were initially left-lateral strike-slip fault systems that formed during Early Miocene and Pleistocene respectively. Colligating with these southward younging left-lateral strike-slip faulting ages and the fact that these convex-northward structures converge to the center segment of active Kunlun fault in the east, we thus considered the Kunbei and Qimen Tagh fault systems as former western segments of the Kunlun fault once located further south in the present-day location of that fault. These faults gradually migrated northward since the Early Miocene while their kinematics changed from left-lateral strike-slip motion to NE-SW transpression.

  20. Effective slip in pressure-driven Stokes flow

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Stone, Howard A.

    2003-08-01

    Nano-bubbles have recently been observed experimentally on smooth hydrophobic surfaces; cracks on a surface can likewise be the site of bubbles when partially wetting fluids are used. Because these bubbles may provide a zero shear stress boundary condition and modify considerably the friction generated by the solid boundary, it is of interest to quantify their influence on pressure-driven flow, with particular attention given to small geometries. We investigate two simple configurations of steady pressure-driven Stokes flow in a circular pipe whose surface contains periodically distributed regions of zero surface shear stress. In the spirit of experimental studies probing slip at solid surfaces, the effective slip length of the resulting flow is evaluated as a function of the degrees of freedom describing the surface heterogeneities, namely the relative width of the no-slip and no-shear stress regions and their distribution along the pipe. Comparison of the model with experimental studies of pressure-driven flow in capillaries and microchannels reporting slip is made and a possible interpretation of the experimental results is offered which is consistent with a large number of distributed slip domains such as nano-size and micron-size nearly flat bubbles coating the solid surface. Further, the possibility is suggested of a shear-dependent effective slip length, and an explanation is proposed for the seemingly paradoxical behaviour of the measured slip length increasing with system size, which is consistent with experimental results to date.

  1. Geodetic slip rate estimates for the Alhama de Murcia and Carboneras faults in the SE Betics, Spain

    NASA Astrophysics Data System (ADS)

    Khazaradze, Giorgi; Echeverria, Anna; Masana, Eulàlia

    2016-04-01

    The Alhama de Murcia and the Carboneras faults are the most prominent geologic structures within the Eastern Betic Shear Zone (EBSZ), located in SE Spain. Using continuous and campaign GPS observations conducted during the last decade, we were able to confirm the continuing tectonic activity of these faults by quantifying their geodetic slip-rates and comparing the estimated values with the geological (including paleoseismological) observations. We find that the bulk of the observed deformation is concentrated around the Alhama de Murcia (AMF) and the Palomares (PF) faults. The geodetic horizontal slip rate (reverse-sinistral) of 1.5±0.3 mm/yr calculated for the AMF and PF fault system is in good agreement with geological observations at the AMF, as well as, the focal mechanism of the 2011 Lorca earthquake, suggesting a main role of the AMF. We also find that the geodetic slip rate of the Carboneras fault zone (CFZ) is almost purely sinistral strike-slip with a rate of 1.3±0.2 mm/yr along N48° direction, very similar to 1.1 mm/yr geologic slip-rate, estimated from recent onshore and offshore paleoseismic and geomorphologic studies. The fact the geodetic and the geologic slip-rates are similar at the AMF and CF faults, suggests that both faults have been tectonically active since Quaternary, slipping at approximately at constant rate of 1.1 to 1.8 mm/yr. Since the existing GPS data cannot discern whether the CFZ is slipping seismically or aseismically, we have intended to relate the on-going seismic activity to the slip-rates estimated using GPS. For this reason we compared seismic and geodetic strain rates, where the latter are larger than seismic strain rates, suggesting the presence of aseismic processes in the area. Nevertheless, due to the large earthquake recurrence intervals, we may be underestimating the seismic strain rates. The direction of the P and T average stress axes are in good agreement with geodetic principal strain rate axes. To summarize, in

  2. Portable active interrogation system.

    SciTech Connect

    Moss, C. E.; Brener, M. W.; Hollas, C. L.; Myers, W. L.

    2004-01-01

    The system consists of a pulsed DT neutron generator (5 x 10{sup 7} n/s) and a portable but high intrinsic efficiency, custom-designed, polyethylene-moderated {sup 3}He neutron detector. A multichannel scaler card in a ruggedized laptop computer acquires the data. A user-friendly LabVIEW program analyzes and displays the data. The program displays a warning message when highly enriched uranium or any other fissionable materials is detected at a specified number of sigmas above background in the delayed region between pulses. This report describes the system and gives examples of the response of the system to highly enriched uranium and some other fissionable materials, at several distances and with various shielding materials.

  3. Slip-stick and the evolution of frictional strength.

    PubMed

    Ben-David, Oded; Rubinstein, Shmuel M; Fineberg, Jay

    2010-01-01

    The evolution of frictional strength has great fundamental and practical importance. Applications range from earthquake dynamics to hard-drive read/write cycles. Frictional strength is governed by the resistance to shear of the large ensemble of discrete contacts that forms the interface that separates two sliding bodies. An interface's overall strength is determined by both the real contact area and the contacts' shear strength. Whereas the average motion of large, slowly sliding bodies is well-described by empirical friction laws, interface strength is a dynamic entity that is inherently related to both fast processes such as detachment/re-attachment and the slow process of contact area rejuvenation. Here we show how frictional strength evolves from extremely short to long timescales, by continuous measurements of the concurrent local evolution of the real contact area and the corresponding interface motion (slip) from the first microseconds when contact detachment occurs to large (100-second) timescales. We identify four distinct and inter-related phases of evolution. First, all of the local contact area reduction occurs within a few microseconds, on the passage of a crack-like front. This is followed by the onset of rapid slip over a characteristic time, the value of which suggests a fracture-induced reduction of contact strength before any slip occurs. This rapid slip phase culminates with a sharp transition to slip at velocities an order of magnitude slower. At slip arrest, 'ageing' immediately commences as contact area increases on a characteristic timescale determined by the system's local memory of its effective contact time before slip arrest. We show how the singular logarithmic behaviour generally associated with ageing is cut off at short times. These results provide a comprehensive picture of how frictional strength evolves from the short times and rapid slip velocities at the onset of motion to ageing at the long times following slip arrest. PMID

  4. New GPS Network on the Active Fault System in Taiwan

    NASA Astrophysics Data System (ADS)

    Hou, C.; Chen, Y.; Hu, J.; Lin, C.; Chen, C.; Wang, J.; Chung, L.; Chung, W.; Hsieh, C.; Chen, Y.

    2004-12-01

    According to the historical records, disastrous earthquakes occurred in Taiwan were caused by reactivations of active faults. In last century, there were five with the surface rupture: 1906 Meishan Eq. (the Meishan F.), 1935 Hsihchu Eq. (the Shihtan and the Tuntzuchiao F.), 1946 Hsinhua Eq. (Hsinhua F.), 1951 Hualien-Taitung Eq. (Longitudinal Valley F.), and 1999 Chi-Chi Eq. (the Chelungpu F.). In order to identify earthquake associated surface rupture and further to mitigate potential hazards, the investigation and monitoring on the active fault system are of great urgency. Central Geological Survey (CGS) of Taiwan is currently executing a 5-year (2002-2006) project, integrating geological and geodetic data to better characterize short-term and long-term spatial and temporal variations in deformation across major already-known active faults of Taiwan. For the former, we use field survey, drilling, geophysical exploration, and trenching to recognize the long-term slip rate and recurrence interval of each fault. For the latter, we deploy near-fault campaign-style GPS and leveling monitoring networks. Here we further combine the result of other GPS networks including continuous-mode. This project is actually concentrated on fault-specific investigation.. Until Dec. 2004, we have set up 756 GPS stations and 27 precise leveling lines including 1024 leveling benchmarks. For the purpose of understanding temporal variability and receive continuous record, the CGS began to deploy 6~10 new GPS stations of continuous mode since 2004. Upon the completion of the geodetic project, we are supposed to provide information on short-term slip rates of major active faults. By integrating other geological datasets we will also evaluate the short-term and long-term behavior of the active faults, and further offer insight into spatial and temporal variability in deformation processes.

  5. No late Quaternary strike-slip motion along the northern Karakoram fault

    NASA Astrophysics Data System (ADS)

    Robinson, Alexander C.; Owen, Lewis A.; Chen, Jie; Schoenbohm, Lindsay M.; Hedrick, Kathryn A.; Blisniuk, Kimberly; Sharp, Warren D.; Imrecke, Daniel B.; Li, Wenqiao; Yuan, Zhaode; Caffee, Marc W.; Mertz-Kraus, Regina

    2015-01-01

    Models that treat long-term evolution of the Tibetan orogen in terms of interactions between rigid blocks require the right-slip Karakoram fault that bounds the western margin of the Tibetan plateau to be a long-lived, stable, high slip-rate feature. While the southern portion of the fault clearly remains active, recent work has proposed that the northern half of the Karakoram fault is currently inactive. New field observations and geochronologic results from the northern end of the Karakoram fault system confirm this interpretation and provide the first quantitative data on the minimum age for the termination of slip. In the southeast Pamir, gravel that yields a U-series age of 198 ± 5 ka on secondary carbonate caps a non-deformed strath terrace that extends across the main strand of the Karakoram fault. The secondary Achiehkopai fault strand is overlain by undisturbed Hangdi glacial stage (24 ± 6 ka) deposits and Dabudar glacial stage (penultimate glacial cycle, ∼ 150 ka, or older) deposits, which lack observable lateral displacement or deformation. Together, these observations show that the northern portion of the Karakoram fault system has not accommodated any detectable strike-slip deformation since at least 24 ± 6 ka, and most likely since ∼ 200 ka or more. These results show that the Karakoram fault system no longer forms a continuous discrete kinematic boundary at the western margin of the Tibetan Plateau. This suggests that even long (> 500 km) strike-slip faults within orogenic belts are inherently unstable features, consistent with models of continental collision zones involving relatively weak crust and distributed deformation.

  6. Slow slip and the transition from fast to slow fronts in the rupture of frictional interfaces

    PubMed Central

    Trømborg, Jørgen Kjoshagen; Sveinsson, Henrik Andersen; Scheibert, Julien; Thøgersen, Kjetil; Amundsen, David Skålid; Malthe-Sørenssen, Anders

    2014-01-01

    The failure of the population of microjunctions forming the frictional interface between two solids is central to fields ranging from biomechanics to seismology. This failure is mediated by the propagation along the interface of various types of rupture fronts, covering a wide range of velocities. Among them are the so-called slow fronts, which are recently discovered fronts much slower than the materials’ sound speeds. Despite intense modeling activity, the mechanisms underlying slow fronts remain elusive. Here, we introduce a multiscale model capable of reproducing both the transition from fast to slow fronts in a single rupture event and the short-time slip dynamics observed in recent experiments. We identify slow slip immediately following the arrest of a fast front as a phenomenon sufficient for the front to propagate further at a much slower pace. Whether slow fronts are actually observed is controlled both by the interfacial stresses and by the width of the local distribution of forces among microjunctions. Our results show that slow fronts are qualitatively different from faster fronts. Because the transition from fast to slow fronts is potentially as generic as slow slip, we anticipate that it might occur in the wide range of systems in which slow slip has been reported, including seismic faults. PMID:24889640

  7. Block model of western US kinematics from inversion of geodetic, fault slip, and earthquake data

    NASA Astrophysics Data System (ADS)

    McCaffrey, R.

    2003-12-01

    The active deformation of the southwestern US (30° to 41° N) is represented by a finite number of rotating, elastic spherical caps. Horizontal GPS velocities (1583), fault slip rates (94), and earthquake slip vectors (116) are inverted for block angular velocities, locking on block-bounding faults, and the rotation of individual GPS velocity fields relative to North America. GPS velocities are modeled as a combination of rigid block rotations and elastic strain rates resulting from interactions of adjacent blocks across bounding faults. The resulting Pacific - North America pole is indistinguishable from that of Beavan et al. (2001) and satisfies spreading in the Gulf of California and earthquake slip vectors in addition to GPS. The largest blocks, the Sierra Nevada - Great Valley and the eastern Basin and Range, show internal strain rates, after removing the elastic component, of only a few nanostrain/a, demonstrating long term approximately rigid behavior. Most fault slip data are satisfied except that the San Jacinto fault appears to be significantly faster than inferred from geology while the Coachella and San Bernardino segments of the San Andreas fault are slower, suggesting the San Andreas system is straightening out in Southern California. Vertical axis rotation rates for most blocks are clockwise and in magnitude more like the Pacific than North America. One exception is the eastern Basin and Range (242° E to 248° E) which rotates slowly anticlockwise about a pole offshore Baja.

  8. Slow slip and the transition from fast to slow fronts in the rupture of frictional interfaces.

    PubMed

    Trømborg, Jørgen Kjoshagen; Sveinsson, Henrik Andersen; Scheibert, Julien; Thøgersen, Kjetil; Amundsen, David Skålid; Malthe-Sørenssen, Anders

    2014-06-17

    The failure of the population of microjunctions forming the frictional interface between two solids is central to fields ranging from biomechanics to seismology. This failure is mediated by the propagation along the interface of various types of rupture fronts, covering a wide range of velocities. Among them are the so-called slow fronts, which are recently discovered fronts much slower than the materials' sound speeds. Despite intense modeling activity, the mechanisms underlying slow fronts remain elusive. Here, we introduce a multiscale model capable of reproducing both the transition from fast to slow fronts in a single rupture event and the short-time slip dynamics observed in recent experiments. We identify slow slip immediately following the arrest of a fast front as a phenomenon sufficient for the front to propagate further at a much slower pace. Whether slow fronts are actually observed is controlled both by the interfacial stresses and by the width of the local distribution of forces among microjunctions. Our results show that slow fronts are qualitatively different from faster fronts. Because the transition from fast to slow fronts is potentially as generic as slow slip, we anticipate that it might occur in the wide range of systems in which slow slip has been reported, including seismic faults. PMID:24889640

  9. Slip of Spreading Viscoplastic Droplets.

    PubMed

    Jalaal, Maziyar; Balmforth, Neil J; Stoeber, Boris

    2015-11-10

    The spreading of axisymmetric viscoplastic droplets extruded slowly on glass surfaces is studied experimentally using shadowgraphy and swept-field confocal microscopy. The microscopy furnishes vertical profiles of the radial velocity using particle image velocimetry (PIV) with neutrally buoyant tracers seeded in the fluid. Experiments were conducted for two complex fluids: aqueous solutions of Carbopol and xanthan gum. On untreated glass surfaces, PIV demonstrates that both fluids experience a significant amount of effective slip. The experiments were repeated on glass that had been treated to feature positive surface charges, thereby promoting adhesion between the negatively charged polymeric constituents of the fluids and the glass surface. The Carbopol and xanthan gum droplets spread more slowly on the treated surface and to a smaller radial distance. PIV demonstrated that this reduced spreading was associated with a substantial reduction in slip. For Carbopol, the effective slip could be eliminated entirely to within the precision of the PIV measurements; the reduction in slip was less effective for xanthan gum, with a weak slip velocity remaining noticeable. PMID:26418827

  10. Slip ring experience in long duration space applications

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1986-01-01

    Ball Aerospace experience with slip rings in space extends back to 1962. Over 40 multi-ring assemblies have been flown and continuous operating lifetimes greater than 8 years at up to 60 rpm have been demonstrated. Slip rings provide multi-channel transfer of electrical power and signals in assemblies that are small in size and weight, and low in cost. By use of multiple brushes and sufficient copper within the assembly, power transfer efficiency better than 99.95 percent for high voltage circuits can be achieved. A low slip ring failure rate based on actual space operation totalling billions of ring revolutions has been established. Well qualified suppliers who have been making slip rings for space use for over 25 years are available. It is hoped that the suspected problem in SEASAT will not be allowed to prejudice space system designer against these very useful mechanisms.

  11. Frictional melting of peridotite and seismic slip

    NASA Astrophysics Data System (ADS)

    Del Gaudio, P.; di Toro, G.; Han, R.; Hirose, T.; Nielsen, S.; Shimamoto, T.; Cavallo, A.

    2009-06-01

    rates, (1) the "thermal" (as it includes the thermally activated first and second weakening) slip distance to achieve steady state from the first peak in strength decreased with increasing normal stress and slip rate and (2) the steady state shear stress slightly increased with increasing normal stress and, for a given normal stress, decreased with increasing slip rate. The ratio of shear stress versus normal stress was about 0.15, well below the typical friction coefficient of rocks (0.6-0.8). The dependence of steady state shear stress with normal stress was described by means of a constitutive equation for melt lubrication. The presence of microstructures similar to those found in natural pseudotachylytes and the determination of a constitutive equation that describes the experimental data allows extrapolation of the experimental observations to natural conditions and to the study of rupture dynamics in mantle rocks.

  12. Geochemistry and fluid inclusions across a crustal strike-slip Mesozoic fault: insights of fluid-flow / rock interaction in the Atacama Fault System

    NASA Astrophysics Data System (ADS)

    Gomila, R.; Mitchell, T. M.; Arancibia, G.; Jensen, E.; Rempe, M.; Cembrano, J. M.; Hoshino, K.; Faulkner, D.

    2012-12-01

    Faults architecture and their permeability related fractures play a first order role in fluid-flow migration throughout the upper crust. Commonly, the interaction between fluid-flow migration and host rock is reflected as mineral precipitation in a vein mesh and/or as mineralogical changes (alteration) of the host rock. Often, however, the relationship between a fault zone and the fluid-flow passing through it is poorly understood. In order to improve our understanding of this process we have chosen, as a case study, the Jorgillo Fault (JF), which lies within the Atacama Fault System, a trench-parallel large-scale structure developed within Mesozoic rocks of the present-day Coastal Cordillera in northern Chile. The JF is represented as a ca. 18 km long NNW-SSE, in its southern end, to NW-SE, in its northern part, west-ward concave-shape sinistral strike-slip fault showing a maximum left-lateral displacement of about 4 km and a subvertical dip. The fault cuts through crystalline rocks of gabbric, dioritic and granodioritic composition. The JF core is composed by a ca. 1 m wide cataclasite zone bounded by two fault gouge zones ca. 40 cm in average while its minimum damage zone extension, based in field observations, is ca. 2 m wide each side of the core zone. A fault perpendicular transect was mapped and sampled in order to run XRF and XRD analyses of the fault core, damage zone and undeformed protolith. XRF analyses of the rocks revealed that contents of Al and Ca decrease with increasing Si, while Na increases towards the fault core. Fujita et al. (2012) interpreted similar behavior in analysis of rocks belonging to the Coloso Fault, which is genetically and spatially related to the JF, as compositional changes of plagioclase to albite-rich ones due to chloritic-propilitic alteration processes. In the damage zone, L.O.I. data increase towards the fault core but decrease inside the core in its cataclastic zone. This behavior of L.O.I. data is explained by the

  13. Magmatic control along a strike-slip volcanic arc: The central Aeolian arc (Italy)

    NASA Astrophysics Data System (ADS)

    Ruch, J.; Vezzoli, L.; De Rosa, R.; Di Lorenzo, R.; Acocella, V.

    2016-02-01

    The regional stress field in volcanic areas may be overprinted by that produced by magmatic activity, promoting volcanism and faulting. In particular, in strike-slip settings, the definition of the relationships between the regional stress field and magmatic activity remains elusive. To better understand these relationships, we collected stratigraphic, volcanic, and structural field data along the strike-slip central Aeolian arc (Italy): here the islands of Lipari and Vulcano separate the extensional portion of the arc (to the east) from the contractional one (to the west). We collected >500 measurements of faults, extension fractures, and dikes at 40 sites. Most structures are NNE-SSW to NNW-SSE oriented, eastward dipping, and show almost pure dip-slip motion, consistent with an E-W extension direction, with minor dextral and sinistral shear. Our data highlight six eruptive periods during the last 55 ka, which allow considering both islands as a single magmatic system, in which tectonic and magmatic activities steadily migrated eastward and currently focus on a 10 km long × 2 km wide active segment. Faulting appears to mostly occur in temporal and spatial relation with magmatic events, supporting that most of the observable deformation derives from transient magmatic activity (shorter term, days to months), rather than from steady longer-term regional tectonics (102-104 years). More in general, the central Aeolian case shows how magmatic activity may affect the structure and evolution of volcanic arcs, overprinting any strike-slip motion with magma-induced extension at the surface.

  14. Slip-localization within confined gouge powder sheared at moderate to high slip-velocity

    NASA Astrophysics Data System (ADS)

    Reches, Zeev; Chen, Xiaofeng; Morgan, Chance; Madden, Andrew

    2015-04-01

    conditions. The ultra-fine grains and extreme slip localization in these experiments are generally similar to ultra-cataclasites found in exhumed faults-zones, and the intensely pulverized gouge found in drilling across active faults.

  15. Whillans Ice Plain Stick Slip

    NASA Astrophysics Data System (ADS)

    Lipovsky, B.; Dunham, E. M.

    2015-12-01

    Concern about future sea level rise motivates the study of fast flowing ice. The Whillans Ice Plain (WIP) region of the West Antarctic Ice Sheet is notable for decelerating from previously fast motion during the instrumental record. Since most ice flux in Antarctica occurs through ice streams, understanding the conditions that cause ice stream stagnation is of basic importance in understanding the continent's contribution to future sea level rise. Although recent progress has been made in understanding the relationship between basal conditions and ice stream motion, direct observation of the temporal variation in subglacial conditions during ice stream stagnation has remained elusive. The Whillans Ice Plain flows to the sea mostly by way of stick-slip motion. We present numerical simulations of this stick-slip motion that capture the inertial dynamics, seismic waves, and the evolution of sliding with rate- and state-dependent basal friction. Large scale stick-slip behavior is tidally modulated and encompasses the entire WIP. Sliding initiates within one of several locked regions and then propagates outward with low average rupture velocity (~ 200 m/s). Sliding accelerates over a period of 200 s attain values as large as 65 m/d. From Newton's second law, this acceleration is ~ T / (rho H) for average shear stress drop T, ice thickness H, and ice density rho. This implies a 3 Pa stress drop that must be reconciled with the final stress drop of 300 Pa inferred from the total slip and fault dimensions. A possible explanation of this apparent discrepancy is that deceleration of the ice is associated with a substantial decrease in traction within rate-strengthening regions of the bed. During these large-scale sliding events, m-scale patches at the bed produce rapid (20 Hz) stick-slip motion. Each small event occurs over ~ 1/100 s, produces ~ 40 microns of slip, and gives rise to a spectacular form of seismic tremor. Variation between successive tremor episodes allows us

  16. Slip-Cast Superconductive Parts

    NASA Technical Reports Server (NTRS)

    Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

    1993-01-01

    Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

  17. Modelling Paleoearthquake Slip Distributions using a Gentic Algorithm

    NASA Astrophysics Data System (ADS)

    Lindsay, Anthony; Simão, Nuno; McCloskey, John; Nalbant, Suleyman; Murphy, Shane; Bhloscaidh, Mairead Nic

    2013-04-01

    Along the Sunda trench, the annual growth rings of coral microatolls store long term records of tectonic deformation. Spread over large areas of an active megathrust fault, they offer the possibility of high resolution reconstructions of slip for a number of paleo-earthquakes. These data are complex with spatial and temporal variations in uncertainty. Rather than assuming that any one model will uniquely fit the data, Monte Carlo Slip Estimation (MCSE) modelling produces a catalogue of possible models for each event. From each earthquake's catalogue, a model is selected and a possible history of slip along the fault reconstructed. By generating multiple histories, then finding the average slip during each earthquake, a probabilistic history of slip along the fault can be generated and areas that may have a large slip deficit identified. However, the MCSE technique requires the production of many hundreds of billions of models to yield the few models that fit the observed coral data. In an attempt to accelerate this process, we have designed a Genetic Algorithm (GA). The GA uses evolutionary operators to recombine the information held by a population of possible slip models to produce a set of new models, based on how well they reproduce a set of coral deformation data. Repeated iterations of the algorithm produce populations of improved models, each generation better satisfying the coral data. Preliminary results have shown the GA to be capable of recovering synthetically generated slip distributions based their displacements of sets of corals faster than the MCSE technique. The results of the systematic testing of the GA technique and its performance using both synthetic and observed coral displacement data will be presented.

  18. Steadily propagating slip pulses driven by thermal decomposition

    NASA Astrophysics Data System (ADS)

    Platt, John D.; Viesca, Robert C.; Garagash, Dmitry I.

    2015-09-01

    Geophysical observations suggest that mature faults weaken significantly at seismic slip rates. Thermal pressurization and thermal decomposition are two mechanisms commonly used to explain this dynamic weakening. Both rely on pore fluid pressurization with thermal pressurization achieving this through thermal expansion of native solids and pore fluid and thermal decomposition by releasing additional pore fluid during a reaction. Several recent papers have looked at the role thermal pressurization plays during a dynamically propagating earthquake, but no previous models have studied the role of thermal decomposition. In this paper we present the first solutions accounting for thermal decomposition during dynamic rupture, solving for steady state self-healing slip pulses propagating at a constant rupture velocity. First, we show that thermal decomposition leads to longer slip durations, larger total slips, and a distinctive along-fault slip rate profile. Next, we show that accounting for more than one weakening mechanism allows multiple steady slip pulses to exist at a given background stress, with some solutions corresponding to different balances between thermal pressurization and thermal decomposition, and others corresponding to activating a single reaction multiple times. Finally, we study how the rupture properties depend on the fault properties and show that the impact of thermal decomposition is largely controlled by the ratio of the hydraulic and thermal diffusivities χ = αhy/αth and the ratio of pore pressure generated to temperature rise buffered by the reaction Pr/Er.

  19. Response to comment on "No late Quaternary strike-slip motion along the northern Karakoram fault"

    NASA Astrophysics Data System (ADS)

    Robinson, Alexander C.; Owen, Lewis A.; Chen, Jie; Schoenbohm, Lindsay M.; Hedrick, Kathryn A.; Blisniuk, Kimberly; Sharp, Warren D.; Imrecke, Daniel B.; Li, Wenqiao; Yuan, Zhaode; Caffee, Marc W.; Mertz-Kraus, Regina

    2016-06-01

    In their comment on "No late Quaternary strike-slip motion along the northern Karakoram fault", while Chevalier et al. (2016) do not dispute any of the results or interpretations regarding our observations along the main strand of the northern Karakoram fault, they make several arguments as to why they interpret the Kongur Shan Extensional System (KES) to be kinematically linked to the Karakoram fault. These arguments center around how an "active" fault is defined, how slip on segments of the KES may be compatible with dextral shear related to continuation of the Karakoram fault, and suggestions as to how the two fault systems might still be connected. While we appreciate that there are still uncertainties in the regional geology, we address these comments and show that their arguments are inconsistent with all available data, known geologic relationships, and basic kinematics.

  20. What causes an icy fault to slip? Investigating the depth and frictional conditions for tidally driven Coulomb failure along major strike-slip faults of Europa and Ganymede

    NASA Astrophysics Data System (ADS)

    Cameron, Marissa E.; Smith-Konter, Bridget R.; Pappalardo, Robert T.

    2014-11-01

    The surfaces of Europa and Ganymede display strike-slip fractures, presumably arising from a combination of global and local stress sources. To better understand the role of tidal stress sources and implications for strike-slip faulting on these icy bodies, we investigate the relationship between shear and normal stresses at several major fault zones: Agenor Linea, Rhadamanthys Linea, Agave/Asterius Lineae, and Astypalaea Linea (on Europa), and Dardanus Sulcus (on Ganymede). Assuming tidal diurnal and non-synchronous rotation (NSR) stresses as plausible mechanisms for strike-slip tectonism, here we investigate the mechanics of Coulomb shear failure. We consider a range of friction coefficients (µf = 0.2 - 0.6) and fault depths (0 - 6 km) to evaluate how failure predictions vary between the satellites and as a function of depth, ice friction, geographic location, and fault geometry. Assuming present-day orbital eccentricities, our results indicate that the conditions for failure at depth are not met for any of the fault systems if subject to diurnal stresses only. Alternatively, models that include both diurnal and NSR stresses readily generate stress magnitudes that could permit shear failure. On Europa, shear failure is easily activated and failure extends to depths ranging from 3 - 6 km when a low coefficient of friction (µf = 0.2) is assumed. On Ganymede, failure is limited to even shallower depths (< 2 km). A high coefficient of friction (µf = 0.6) limits failure depths to < 3 km on Europa faults and discourages strike-slip faulting completely on Ganymede. Based on these results, we infer that the conditions for shear failure are potentially met along at least these five studied systems, and possibly others in the outer solar system, if NSR is adopted as a driving stress mechanism and the coefficient of friction is low.

  1. Slip zone structure and processes in seismogenic carbonate faults

    NASA Astrophysics Data System (ADS)

    Bullock, R. J.; De Paola, N.

    2011-12-01

    High velocity rotary shear experiments performed at seismic slip velocities (>1 m/s) have shown that experimental faults are weak; with increasing displacement, friction coefficient values decrease from Byerlee's values (μ = 0.6-0.85) to values of ~0.1. In carbonate rocks, experimental studies have shown that fault lubrication is due to the operation of multiple dynamic weakening mechanisms (e.g., flash heating, thermal pressurization, nanoparticle lubrication), which are thermally activated due to the frictional heat generated along localized slip surfaces during rapid slip. This study has set out to investigate whether evidence for the operation of these weakening mechanisms can be found in naturally occurring carbonate fault zones. Field studies were carried out on the active Gubbio fault zone (1984, Mw = 5.6) in the northern Apennines of Italy. Jurassic-Oligocene carbonates in the footwall are heavily deformed within a fault core of ~15 m thickness, which contains a number of very well exposed, highly localized principal slip surfaces (PSSs). Fault rocks are predominantly breccias and foliated cataclasites. Microstructural analyses of the PSSs reveal that slip is localized within very narrow principal slip zones (PSZs), ranging from 10-85 μm in thickness, with sub-millimetre scale asperities. PSZs are composed of very fine-grained, orange-brown ultracataclasite gouge containing a high proportion of nano-sized particles. The ultracataclasite commonly displays a foliated texture and sub-micron scale zones of extreme shear localization. A broader slip zone, up to 1.5 mm wide and containing multiple slip surfaces, is associated with the most evolved PSSs; it is located on the opposite side of the PSS to the PSZ. Here, the host rock material is heavily fractured, abraded and altered, sometimes with an ultracataclasite matrix. The surrounding wall rock often appears to have a porous texture, and calcite crystals within the slip zone have altered rims with lobate

  2. Slow-Slip Propagation Speeds

    NASA Astrophysics Data System (ADS)

    Rubin, A. M.; Ampuero, J.

    2007-12-01

    Combined seismic and geodetic data from subduction zones and the Salton Trough have revealed slow slip events with reasonably well-defined propagation speeds. This in turn is suggestive of a more-or-less well- defined front separating nearly locked regions outside the slipping zone from interior regions that slide much more rapidly. Such crack-like nucleation fronts arise naturally in models of rate-and-state friction for lab-like values of a/b, where a and b are the coefficients of the velocity- and state-dependence of the frictional strength (with the surface being velocity-neutral for a/b=1). If the propagating front has a quasi-steady shape, the propagation and slip speeds are kinematically tied via the local slip gradient. Given a sufficiently sharp front, the slip gradient is given dimensionally by Δτp- r/μ', where Δτp-r is the peak-to-residual stress drop at the front and μ' the effective elastic shear modulus. Rate-and-state simulations indicate that Δτp-r is given reasonably accurately by bσ\\ln(Vmaxθi/Dc), where σ is the effective normal stress, Vmax is the maximum slip speed behind the propagating front, θi is the the value of "state" ahead of the propagating front, and Dc is the characteristic slip distance for state evolution. Except for a coefficient of order unity, Δτp-r is independent of the evolution law. This leads to Vprop/Vmax ~μ'/[bσ\\ln(Vmaxθi/Dc)]. For slip speeds a few orders of magnitude above background, \\ln(Vmaxθi/Dc) can with reasonable accuracy be assigned some representative value (~4-5, for example). Subduction zone transients propagate on the order of 10 km/day or 10-1 m/s. Geodetic data constrain the average slip speed to be a few times smaller than 1 cm/day or 10-7 m/s. However, numerical models indicate that the maximum slip speed at the front may be several times larger than the average, over a length scale that is probably too small to resolve geodetically, so a representative value of Vprop/Vmax may be ~106

  3. Seismic Slip on an Oblique Detachment Fault at Low Angles

    NASA Astrophysics Data System (ADS)

    Janecke, S. U.; Steely, A. N.; Evans, J. P.

    2008-12-01

    Pseudotachylytes are one of the few accepted indicators of seismic slip along ancient faults. Low-angle normal faults have produced few large earthquakes in historic times and low-angle normal faults (detachment faults) are typically severely misoriented relative to a vertical maximum compressive stress. As a result many geoscientists question whether low-angle normal faults produce earthquakes at low angles. Relationships in southern California show that a major low-angle normal-oblique fault slipped at low angles and produced large earthquakes. The exhumed Late Cenozoic West Salton detachment fault preserves spectacular fault- related pseudotachylytes along its fault plane and injected into its hanging wall and footwall. Composite pseudotachylyte zones are up to 1.25 m thick and persists over lateral distances of at least 10's of meters. Pseudotachylyte is common in most thin sections of damaged fault rocks with more than 20% (by volume) of cataclasite. We recognized the presence of original melt using numerous criteria: abundant spherulites in thin sections, injection structures at both the thin-section and outcrop scale, black aphanitic textures, quenched vein margins, variations in microcrystallite textures and/or size with respect to the vein margin, and glassy textures in hand sample. Multiple earthquakes are inferred to produce the layered "stratigraphy" in some exposures of pseudotachylytes. We infer that the West Salton detachment fault formed and slipped at low angles because it nearly perfectly reactivates a Cretaceous ductile thrust system at the half km scale and dips between 10 and 45 degrees. The about 30 degree NNE dip of the detachment fault on the north side of Yaqui Ridge is likely steeper than its dip during detachment slip because there is local steepening on the flanks of the Yaqui Ridge antiform in a contractional stepover of a crosscutting Quaternary San Felipe dextral fault zone. These relationships indicate a low dip on the detachment

  4. On first cycle slip time of phase-locked loops in cascade

    NASA Technical Reports Server (NTRS)

    Yuen, J. H.

    1974-01-01

    Precise measurement and spacecraft tracking are obtained by using phase-locked loops in cascade in two-way communications links. Statistics on cycle slip time are of vital importance in system planning and design. This paper presents: (1) results of a computer simulation study of the mean time to first cycle slip of cascade phase-locked loops preceded by bandpass limiters, and (2) the determination of probability distributions of cycle slip. Numerical results are obtained for a typical coherent communication system.

  5. Acoustic properties of the full spectrum of stick-slip events from stable sliding to dynamic rupture: insights on the mechanics of slow earthquakes and transient fault slip.

    NASA Astrophysics Data System (ADS)

    Scuderi, M. M.; Marone, C.; Tinti, E.; Di Stefano, G.; Collettini, C.

    2015-12-01

    Seismic and geodetic observations show that fault slip occurs via a spectrum of behaviors that include slow earthquakes and tectonic tremor. These phenomena have been observed in a variety of tectonic environments worldwide, however the underlying processes are poorly understood. Here we report on lab experiments on simulated fault gouge. We used the double direct shear configuration and varied the loading system stiffness (k) to produce the full spectrum of stick-slip behaviors, with durations ranging from 10-3 to 1 second. We measured frictional rheology and elastic wave properties throughout the stick-slip cycle for slow and fast events. When the loading stiffness is greater than the fault zone critical rheologic stiffness (kc) we observe stable frictional sliding. For k≈kc we document emergent slow-slip events from steady shear. When kc>k we observe audible stick-slip. Stick slip stress drop and event duration vary systematically as a function of the ratio k/kc. For slow-slip events, p-wave velocity (Vp) begins to decrease prior to the stress drop and the maximum slip velocity during failure coincides with the largest drop in Vp. Dynamic stick-slip events do not show precursory changes in Vp prior to failure. We find that fault creep and precursory changes in wave properties vary systematically with stick-slip event duration, with slower events showing larger precursory changes. In general, Vp begins to decrease prior to failure and drops abruptly as slip velocity accelerates to a peak value. The drop in Vp appears to be larger during dynamic stick-slip than for slow-slip events. Our results suggest that slow earthquakes and transient fault slip are governed by the same frictional processes as dynamic stick-slip and represent a continuum in the spectrum of fault slip. We show that fault gouge elastic properties evolve during the pre-seismic stage of slow-slip, which could provide an important means of assessing short term seismic hazard.

  6. Assessing the role of fluids in episodic tremor and slip events using active seismic sources: results from a prototype experiment in Cascadia (Invited)

    NASA Astrophysics Data System (ADS)

    Niu, F.; Silver, P. G.; Nigbor, R.

    2009-12-01

    Recently, the so-called episodic tremor and slip (ETS) that consist of seismically recorded tremor events with characteristic frequencies of 1-15 Hz and slow slip events observed by GPS and strainmeters with durations of order weeks were widely observed in a variety of environments worldwide. While the community continues to make interesting observations, the underlying physical process remains poorly understood. There have been many proposed mechanisms, most of which invoke fluids. Many observations suggest that ETS can be triggered by very small stresses despite the high confining pressures at the depth of ETS, which has led many to conclude that fluids at the slab interface are under lithostatic pressure, and that furthermore there is likely fluid flow at the time of ETS events. Thus far, there is little data with which to evaluate these ideas. We have been interested in determining whether or not there are spatiotemporal structural changes in the crust and upper-most mantle associated with this phenomenon. We conducted a control-source experiment in Cascadia to examine the feasibility of using the reflection/scattering waves from the slab interface to look for structural changes that may reflect the migration of fluids. We selected a highly repeatable source, an eccentric-mass “shaker” designed for engineering studies, as the seismic source. The shaker was provided by NEES@UCLA. A 15’x15’ cement pad for installing the shaker was built on basaltic bedrock that is part of the Tertiary volcanic rocks of the Crescent Formation. We deployed arrays of short period instruments at two distances from the source: 30km and 90km away. The 90km array was deployed at the site of a previous deployment of the A of A team at Big Skidder Hill. Including our stations and those of A of A, we had 32 seismometers in all. The array has a station spacing of 60-100 m and an aperture about 1 to 1.5 km. During our experiment period, we were able to record a quarry blast near our

  7. Hydrodynamic slip in silicon nanochannels

    NASA Astrophysics Data System (ADS)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-03-01

    Equilibrium and nonequilibrium molecular dynamics simulations were performed to better understand the hydrodynamic behavior of water flowing through silicon nanochannels. The water-silicon interaction potential was calibrated by means of size-independent molecular dynamics simulations of silicon wettability. The wettability of silicon was found to be dependent on the strength of the water-silicon interaction and the structure of the underlying surface. As a result, the anisotropy was found to be an important factor in the wettability of these types of crystalline solids. Using this premise as a fundamental starting point, the hydrodynamic slip in nanoconfined water was characterized using both equilibrium and nonequilibrium calculations of the slip length under low shear rate operating conditions. As was the case for the wettability analysis, the hydrodynamic slip was found to be dependent on the wetted solid surface atomic structure. Additionally, the interfacial water liquid structure was the most significant parameter to describe the hydrodynamic boundary condition. The calibration of the water-silicon interaction potential performed by matching the experimental contact angle of silicon led to the verification of the no-slip condition, experimentally reported for silicon nanochannels at low shear rates.

  8. Active Response Gravity Offload System

    NASA Technical Reports Server (NTRS)

    Valle, Paul; Dungan, Larry; Cunningham, Thomas; Lieberman, Asher; Poncia, Dina

    2011-01-01

    The Active Response Gravity Offload System (ARGOS) provides the ability to simulate with one system the gravity effect of planets, moons, comets, asteroids, and microgravity, where the gravity is less than Earth fs gravity. The system works by providing a constant force offload through an overhead hoist system and horizontal motion through a rail and trolley system. The facility covers a 20 by 40-ft (approximately equals 6.1 by 12.2m) horizontal area with 15 ft (approximately equals4.6 m) of lifting vertical range.

  9. A priori models for predicting drag reduction for flow over heterogeneous slip boundaries

    NASA Astrophysics Data System (ADS)

    Heck, Margaret; Papavassiliou, Dimitrios

    2015-11-01

    Slip at fluid-fluid/fluid-solid interfaces is a subject of interest for many engineering applications, ranging from porous materials to biomedical devices to separation processes. Despite remarkable effort to include the effects of surface topology and various flow and physical properties in models describing fluid slip, the mathematical description of flow over mixed slip boundaries is still under investigation. Using similarity theory, which is based on the generalized homogeneity of physical laws governing most systems and takes advantage of similarity in the spatial distribution of characteristics of motion, the equivalent slip velocity is shown to be a function of the geometry of a microfluidic system. The results are used to predict the slip velocity for flow over surfaces with periodically repeating no-slip/free-shear boundaries in the shape of rectangles for 16%-50% solid fractions. The equivalent slip velocity for flow over rectangular boundaries can then be related to the those for flow over surfaces with square and circular no-slip boundaries using characteristic length ratios. The models developed using this apporach can be directly used to estimate the slip velocity for flow over various free-shear/no-slip boundaries for Couette, laminar flow conditions.

  10. Recognising Paleoseismic Events and Slip Styles in Vein Microstructures - is Incrementality Enough?

    NASA Astrophysics Data System (ADS)

    Fagereng, A.; Sibson, R. H.

    2008-12-01

    'Subduction channels', containing highly sheared, fluid-saturated, trench-fill sediments, are commonly present along subduction thrust interfaces. These shear zones accommodate fast plate boundary slip rates (1~-~10~cm/yr) and exhibit high levels of seismicity, accomplishing slip in a broad range of styles including standard earthquakes, slow slip, non-volcanic tremor and aseismic creep. Exhumed subduction channel fault rocks provide a time-integrated record of these varied slip modes though the degree of overprinting may be considerable. The Chrystalls Beach accretionary mélange, within the Otago Schist accretion-collision assemblage, New Zealand, is analogous to an active subduction channel assemblage. It contains asymmetric lenses of sandstone, chert and minor basalt enclosed within a relatively incompetent, cleaved pelitic matrix. This assemblage has been intensely sheared in a mixed continuous/discontinuous style within a flat-lying, <~4~km thick, shear zone. Ductile structures such as folds, S/C-like structures, and asymmetric boudins and clasts formed by soft sediment deformation and pressure solution creep. An extensive anastomosing vein system can be divided into mutually cross-cutting extension fractures (V1) and slickenfibre shear veins (V2). V1 commonly cut competent lenses within the mélange, while V2 mostly follow lithological contacts. Both vein sets are predominantly elongate-blocky with 'crack-seal' extension and shear increments of 10~- ~100~μm. Little sign of wall rock alteration or heating is present adjacent to V1 veins, which likely formed by incremental hydrofracture with episodic fluid influx. Post-fracture drop in Pf promoted solute precipitation from advecting fluids. This process may reflect fracture and fluid flow in a distributed fault-fracture mesh, an often inferred mechanism of non-volcanic tremor. In contrast, wall rock alteration and pressure solution seams are common adjacent to V2 veins. Slickenfibres on these shear surfaces

  11. Frictional melt and seismic slip

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; di Toro, G.; Hirose, T.; Shimamoto, T.

    2008-01-01

    Frictional melt is implied in a variety of processes such as seismic slip, ice skating, and meteorite combustion. A steady state can be reached when melt is continuously produced and extruded from the sliding interface, as shown recently in a number of laboratory rock friction experiments. A thin, low-viscosity, high-temperature melt layer is formed resulting in low shear resistance. A theoretical solution describing the coupling of shear heating, thermal diffusion, and extrusion is obtained, without imposing a priori the melt thickness. The steady state shear traction can be approximated at high slip rates by the theoretical form τss = σn1/4 (A/?) ? under a normal stress σn, slip rate V, radius of contact area R (A is a dimensional normalizing factor and W is a characteristic rate). Although the model offers a rather simplified view of a complex process, the predictions are compatible with experimental observations. In particular, we consider laboratory simulations of seismic slip on earthquake faults. A series of high-velocity rotary shear experiments on rocks, performed for σn in the range 1-20 MPa and slip rates in the range 0.5-2 m s-1, is confronted to the theoretical model. The behavior is reasonably well reproduced, though the effect of radiation loss taking place in the experiment somewhat alters the data. The scaling of friction with σn, R, and V in the presence of melt suggests that extrapolation of laboratory measures to real Earth is a highly nonlinear, nontrivial exercise.

  12. Slip rate and tremor genesis in Cascadia

    NASA Astrophysics Data System (ADS)

    Wech, Aaron G.; Bartlow, Noel M.

    2014-01-01

    At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

  13. Characterizing the Relationship of Tremor and Slip during Recent ETS Events in Northern Cascadia using Strainmeters, GPS, and Tremor Observations

    NASA Astrophysics Data System (ADS)

    Krogstad, R. D.; Schmidt, D. A.

    2014-12-01

    We investigate the relationship between slip and tremor during multiple recent slow slip events in northern Cascadia. While the relationship of geodetically detectable slow slip and nonvolcanic tremor appears to be broadly coincident, the exact spatial and temporal characteristics remain unclear at a finer scale. Typical GPS derived slip distributions tend to be spatially and temporally smoothed and offset slightly updip of tremor distributions. These discrepancies may be real, or they may be a consequence of the resolution of GPS data or an artifact of the inversion methodology. Borehole strainmeters provide additional independent geodetic constraints for characterizing slip, provide greater temporal resolution, and greater precision than GPS. However, various non-tectonic artifacts and other sources of error have limited the number of usable stations and made deriving reliable information from strainmeters during slip events difficult. We utilize strainmeters with low levels of noise and minimal observable artifacts to constrain forward models and to provide additional independent observations in joint geodetic inversions with GPS data. A series of slip distributions are derived by inverting strainmeter and GPS data using the Kalman-filter-based Extended Network Inversion Filter. To compare the tremor distributions to the geodetically derived slip we also construct slip distributions using tremor occurrences as a proxy for localized slip on the plate interface. The magnitude of slip per tremor occurrence is then scaled to best match the observed surface displacements. Separate slip distributions informed by GPS and tremor are then used to predict strain time series. The comparisons between strain predictions and observations produce mixed results. This may indicate that that tremor and slip are not always coincident. This is particularly evident during the Aug. 2010 event, where the peak GPS-derived slip is located in a region with decreased tremor activity

  14. The three-dimensional pattern of crustal deformation associated with active normal fault systems observed using continuous GPS geodesy

    NASA Astrophysics Data System (ADS)

    Bennett, R. A.; Hreinsdottir, S.

    2009-12-01

    Geological examples of shallow dipping normal faults with large displacements are exposed at numerous locations throughout the world and it is widely recognized that extensional deformation at brittle crustal levels is most efficiently accomplished by slip across such structures. It has previously been shown that lower dip angles reduce the regional stresses required to drive large horizontal displacements. Nevertheless, the traditional theory of fault mechanics—based on Anderson’s classification of stress regimes, the Coulomb failure criterion, and Byerlee’s friction law—precludes such faults from slipping at low angle. Observational support for this traditional theory includes the absence of large unequivocally low-angle normal fault earthquakes in the global catalog; all well-determined normal fault earthquakes appear to have occurred on moderate to steeply dipping planes. However, precise measurements of 3D crustal motions based on continuous GPS in central Italy and Utah reveal deformation patterns across active normal fault systems that are inconsistent with active slip across steeply dipping planes. Instead, the combination of observed horizontal and vertical surface motions are consistent with slip across low angle surfaces independently imaged in the subsurface by seismic reflection and other geophysical data. For the Alto Tiberina fault in central Italy, active aseismic creep occurs at shallow crustal levels, most likely within the brittle-frictional regime at which Andersonian-Byerlee fault mechanics should be applicable. The actively creeping portion of the fault inferred using GPS geodesy correlates well with the observed pattern of micro-seismicity, which concentrates along the inferred subsurface fault plane. GPS measurements across the greater Wasatch fault zone in the vicinity of Salt Lake City, Utah, reveal crustal motions consistent with aseismic displacement across a shallow dipping fault or sub-horizontal shear zone at mid

  15. Slip stacking experiments at Fermilab main injector

    SciTech Connect

    Kiyomi Koba et al.

    2003-06-02

    In order to achieve an increase in proton intensity, Fermilab Main Injector will use a stacking process called ''slip stacking''. The intensity will be doubled by injecting one train of bunches at a slightly lower energy, another at a slightly higher energy, then bringing them together for the final capture. Beam studies have started for this process and we have already verified that, at least for a low beam intensity, the stacking procedure works as expected. For high intensity operation, development work of the feedback and feedforward systems is under way.

  16. The JET Neutron Activation System

    NASA Astrophysics Data System (ADS)

    Roquemore, A. L.; Bertalot, L.; Esposito, B.; Jarvis, O. N.; Loughlin, M. J.; Sadler, G.; van Belle, P.

    1997-11-01

    The JET activation system provides the absolute value of the neutron yields as well as a check on the linearity of other neutron detector systems. The total neutron yield is standardized to one irradiation end reentrant in the top of the vessel, while the results from the other seven irradiation ends are normalized to this standard end and provide redundancy as well as information on the plasma position. A pneumatic transfer system is used to transfer up to five capsules containing elemental foils for a single discharge on JET. Eleven different elemental foils have been utilized to determine the yields from both DD and DT plasmas. By placing several different foils with different activation energy thresholds in a single capsule for one DT discharge, neutron spectral information has been obtained by use of the SAND-II unfolding code. A description of the activation system hardware and calibration of the activation detector system will be presented along with the results from the DT neutron calibration campaign.

  17. Relation between surface slip topography and stress corrosion cracking in Ti-8 wt % Al

    NASA Technical Reports Server (NTRS)

    Boyd, J. D.; Hoagland, R. G.

    1974-01-01

    The deformation behavior of Ti-8 wt % Al has been investigated in an inert environment (air), and an aggressive environment (salt water). Details of surface slip geometry were examined by high resolution surface replicas at various stages of deformation in both environments. Specimens aged to contain a fine dispersion of Ti3Al precipitates failed by subcritical crack growth in salt water, whereas specimens in the single phase condition showed no effects of environment on the yield or fracture characteristics. The Ti3Al precipitates produce little change in strength level or slip character compared to the single phase alloy, and there is no evidence of any effects of environment on the character of surface slip. Rather, the presence of trenches along slip bands on the surface of aged specimens suggest that the specific effect of the Ti3Al precipitates is to render the surface slip steps chemically active relative to the surrounding matrix by slip induced dissolution of the particles.

  18. Modeling approaches for active systems

    NASA Astrophysics Data System (ADS)

    Herold, Sven; Atzrodt, Heiko; Mayer, Dirk; Thomaier, Martin

    2006-03-01

    To solve a wide range of vibration problems with the active structures technology, different simulation approaches for several models are needed. The selection of an appropriate modeling strategy is depending, amongst others, on the frequency range, the modal density and the control target. An active system consists of several components: the mechanical structure, at least one sensor and actuator, signal conditioning electronics and the controller. For each individual part of the active system the simulation approaches can be different. To integrate the several modeling approaches into an active system simulation and to ensure a highly efficient and accurate calculation, all sub models must harmonize. For this purpose, structural models considered in this article are modal state-space formulations for the lower frequency range and transfer function based models for the higher frequency range. The modal state-space formulations are derived from finite element models and/or experimental modal analyses. Consequently, the structure models which are based on transfer functions are directly derived from measurements. The transfer functions are identified with the Steiglitz-McBride iteration method. To convert them from the z-domain to the s-domain a least squares solution is implemented. An analytical approach is used to derive models of active interfaces. These models are transferred into impedance formulations. To couple mechanical and electrical sub-systems with the active materials, the concept of impedance modeling was successfully tested. The impedance models are enhanced by adapting them to adequate measurements. The controller design strongly depends on the frequency range and the number of modes to be controlled. To control systems with a small number of modes, techniques such as active damping or independent modal space control may be used, whereas in the case of systems with a large number of modes or with modes that are not well separated, other control

  19. Fault zone connectivity: slip rates on faults in the san francisco bay area, california.

    PubMed

    Bilham, R; Bodin, P

    1992-10-01

    The slip rate of a fault segment is related to the length of the fault zone of which it is part. In turn, the slip rate of a fault zone is related to its connectivity with adjoining or contiguous fault zones. The observed variation in slip rate on fault segments in the San Francisco Bay area in California is consistent with connectivity between the Hayward, Calaveras, and San Andreas fault zones. Slip rates on the southern Hayward fault taper northward from a maximum of more than 10 millimeters per year and are sensitive to the active length of the Maacama fault. PMID:17835127

  20. Provenance of alluvial fan deposits to constrain the mid-term offsets along a strike-slip active fault: the Elsinore fault in the Coyote Mountains, Imperial Valley, California.

    NASA Astrophysics Data System (ADS)

    Masana, Eulalia; Stepancikova, Petra; Rockwell, Thomas

    2013-04-01

    The lateral variation in rates along a fault and its constancy along time is a matter of discussion. To give light to this discussion, short, mid and long term offset distribution along a fault is needed. Many studies analyze the short-term offset distribution along a strike-slip fault that can be obtained by the analysis of offset features imprinted in the morphology of the near-fault area. We present an example on how to obtain the mid- to long-term offset values based on the composition of alluvial fans that are offset by the fault. The study area is on the southern tip of the Elsinore fault, which controls the mountain front of the Coyote Mountains (California). The Elsinore-Laguna Salada fault is part of the San Andreas fault (SAF) system, extending 250 km from the Los Angeles Basin southeastward into the Gulf of California, in Mexico. The slip-rate on the southern Elsinore fault is believed to be moderate based on recent InSAR observations, although a recent study near Fossil Canyon (southern Coyote Mountains) suggests a rate in the range of 1-2 mm/yr. For this study we processed the airborne LiDAR dataset (EarthScope Southern & Eastern California, SoCal) to map short to mid-term alluvial offsets. We reprocessed the point clouds to produce DEMs with 0.5m and 0.25m grids and we varied the insolation angles to illuminate the various fault strands and the offset features. We identified numerous offset features, such as rills, channel bars, channel walls, alluvial fans, beheaded channels and small erosional basins that varied in displacement from 1 to 350 m. For the mid- to long-term offsets of the alluvial fans we benefited from the diverse petrological composition of their sources. Moreover, we recognized that older alluvium, which is offset by greater amounts, is in some cases buried beneath younger alluvial fan deposits and separated by buried soils. To determine the source canyon of various alluvial elements, we quantified the clast assemblage of each source

  1. Hot, Fast Faults: Evidence for High-Temperature Slip on Exhumed Faults, and Insights into Seismic Slip Processes

    NASA Astrophysics Data System (ADS)

    Evans, J. P.; Ault, A. K.; Janecke, S. U.; Prante, M. R.

    2015-12-01

    Microstructural and geochemical techniques combined with prior observations of naturally occurring faults provide insights into slip rates and slip dimensions of seismicity. We review four indicators for high coseismic paleotemperatures in brittle to semi-brittle faults from a wide range of tectonic settings with mm to km of slip. Thin, high-gloss, Fe-rich slip surfaces indicate high-temperature slip occurred on mm- to m-scales. Elliptical and circular zones of concentric iridescence indicate localized sites of elevated temperature that may be caused by heating at asperity contacts. The surface iridescence is associated with changes in Fe oxidation states detected by X-Ray photoelectron spectroscopy. Minimum temperature increases of 300 °C above ambient are supported by geochemical arguments and up to 800 °C are supported by analogs to high-speed friction experiments in steels and ceramics firing in reduced conditions. The presence of clay-rich foliated fault-related rocks, and the presence of nm- to mm-thick clay coatings indicate that syn-kinematic endothermic reactions occur at a range of scales. We suggest these features reflect temperature increases of ≥100-200 °C for activation energy required to drive the clay alteration is sourced from seismic energy and Schleicher-van der Pluijm-type slip surfaces to record instantaneous slip. Dense, low porosity planar porcelainite zones mm- to cm-thick along fault surfaces are the result of sintering of quartz-clay-feldspar mixtures and indicate T≥1000 °C localized along the surfaces, the result of post-slip cooling. Highly indurated, ultrafine fault-related rocks often consists of comminuted grains, vein fragments, and neocrystallized grains that represent retrograde cooling or alteration after peak heating. These observations and those of other recent workers indicate that many naturally occurring exhumed faults record elevated temperatures. In many cases, careful observations can delineate fault slip

  2. Investigating Stress Seources and Fault Parameters Along Major Strike-Slip Lineae on Europa

    NASA Astrophysics Data System (ADS)

    Cameron, M. E.; Smith-Konter, B. R.; Pappalardo, R. T.

    2014-12-01

    The surface of Europa is crosscut by a dense network of structures, many of these representing a complex history of strike-slip tectonic activity, presumably arising from a combination of global and local stress sources. Several dominant (~1000 km) structures span geographically diverse locations of Europa, offering a unique opportunity to study strike-slip activity at the hemispheric scale. These structures also exhibit kilometer-scale geometric bends that can promote or discourage shear failure. To better understand the role of tidal stress sources and implications for strike-slip faulting on Europa, we investigate the relationship between shear and normal stresses at four major fault zones: Agenor Linea, Rhadamanthys Linea, Conamara Chaos (Agave and Asterius Lineae), and Astypalaea Linea. Assuming tidal diurnal and non-synchronous rotation (NSR) stresses as the primary mechanisms for strike-slip tectonism, here we investigate the mechanics of Coulomb shear failure on Europa. We consider a range of friction coefficients (µf = 0.2 - 0.6) and fault depths (0 - 6 km) to evaluate how the predicted failure varies as a function of depth and its dependency on ice friction, geographic location, and fault geometry. Our results indicate that the conditions for failure at depth are not met for any of the lineae if subject to diurnal stresses only. Alternatively, models that include both diurnal and NSR stresses readily generate stress magnitudes that could permit shear failure. Shear failure is easily activated and extends to depths ranging from 3 - 6 km on all four linea systems when a low coefficient of friction (µf = 0.2) is assumed, but is generally limited to depths < 3 km when a high coefficient of friction (µf = 0.6) is applied. Based on these results, we infer that the conditions for shear failure are potentially met along at least these four studied lineae, and possibly others, on Europa when NSR is adopted as a driving stress mechanism and the coefficient of

  3. Accessory slips of the extensor digiti minimi.

    PubMed

    Li, Jing; Mao, Qing Hua

    2014-01-01

    During the educational dissection of a 69-year-old Chinese male cadaver, an extensor digiti minimi (EDM) with five slips on the right hand was discovered. Except for the two slips of the little finger, the two radial slips were inserted into the dorsal aponeurosis of the middle finger and the ring finger, respectively. The middle slip was connected to the junctura tendinum in the fourth intermetacarpal spaces. Variations in this region are of paramount importance for the reconstructive surgeons, who may utilize the accessory slips to restore functional capacity of the fingers. PMID:24970007

  4. Slip rate of the Calico fault: Implications for anomalous geodetic strain accumulation across the Eastern California shear zone

    NASA Astrophysics Data System (ADS)

    Oskin, M.; Perg, L.; Blumentritt, D.; Mukhopadhyay, S.; Iriondo, A.

    2004-12-01

    Recent earthquake activity and high geodetically derived fault-slip rates across the Eastern California shear zone motivate comparisons with long-term geologic deformation rates to test for transient strain accumulation. We report new geologic slip-rate results from a transect at 34.8° N across the central Mojave Desert where six dextral faults (Helendale, Lenwood, Camp Rock, Calico, Pisgah-Bullion, and Ludlow) accommodate all late Quaternary right-lateral displacement. High-resolution LIDAR topography data have been successfully acquired across all six faults as part of a project to measure a complete budget of long-term geologic fault slip rates. Field investigations of the northern Rodman Mountains conducted with the aid of the new topography data identified several surfaces dextrally offset by the Calico fault. A preliminary slip rate of 1.3±0.3 mm/yr is calculated from an 800± 200 m offset of alluvial fan deposits containing clasts of the ca. 600 ka Pipkin basalt flow. Cosmogenic surface exposure age dating of offset geomorphic surfaces and refined Ar/Ar dating of the basalt flow, in progress, will provide multiple constraints of this fault slip rate. The slip rate of the Calico fault is more than twice that of the Blackwater fault, located on strike with the Calico fault in the northwest Mojave Desert. This discrepancy supports that strain is transferred away from the Calico fault and other adjacent northwest-striking dextral faults onto domino-style rotating blocks bounded by sinistral faults in the Fort Irwin region. A newly identified active thrust fault and fault-related fold bounding the northern Rodman mountains accommodates shortening east of the Calico fault that may be caused by space problems at the intersection of these conjugate fault systems. Overall, slip rate on the Calico fault, together with existing paleoseismic histories on adjacent faults, does not account for more than 5 mm/yr of strain accumulation across the Eastern California shear

  5. Dynamically triggered slip and sustained fault gouge instability associated with unique slip behavior under laboratory shear conditions

    NASA Astrophysics Data System (ADS)

    Johnson, P. A.; Carmeliet, J.; Savage, H. M.; Scuderi, M.; Carpenter, B. M.; Guyer, R. A.; Daub, E. G.; Marone, C.

    2015-12-01

    We investigate dynamic-wave triggered slip under laboratory shear conditions. The experiment is comprised of a 3-block system containing two gouge layers composed of glass beads and held in place by a fixed load in a bi-axial configuration. When the system is sheared under steady state conditions at loads from 3-8 MPa, stick-slip exhibiting a characteristic recurrence time is observed. Under these load conditions, we find that shear failure may be instantaneously triggered by a brief dynamical wave if the system is in a critical shear-stress state, near failure. Dynamic triggering is only observed when the dynamic wave amplitude exceeds strains of 10^(-7). Following triggering, the gouge material remains in an unstable state for long periods of time as manifest by unique slip characteristics not observed during spontaneous events: the measured physical characteristics—the gouge material strength recovery, the gouge layer thickness, the gouge shear modulus and the stick-slip recurrence time recover over many stick-slip cycles following triggering. This work suggests that faults must be critically stressed to trigger under dynamic conditions and that the recovery process following a dynamically triggered event differs from the recovery following a spontaneous event.

  6. Slip distribution of the 2010 Mentawai earthquake from GPS observation using least squares inversion method

    NASA Astrophysics Data System (ADS)

    Awaluddin, Moehammad; Yuwono, Bambang Darmo; Puspita, Yolanda Adya

    2016-05-01

    Continuous Global Positioning System (GPS) observations showed significant crustal displacements as a result of the 2010 Mentawai earthquake. The Least Square Inversion method of Mentawai earthquake slip distribution from SuGAR observations yielded in an optimum value of slip distribution by giving a weight of smoothing constraint and a weight of slip value constraint = 0 at the edge of the earthquake rupture area. A maximum coseismic slip of the inversion calculation was 1.997 m and concentrated around stations PRKB (Pagai Island). In addition, the values of dip-slip direction tend to be more dominant. The seismic moment calculated from the slip distribution was 6.89 × 10E+20 Nm, which is equivalent to a magnitude of 7.8.

  7. Biodegradable polymers: Wall slip, melt fracture, and processing aids

    NASA Astrophysics Data System (ADS)

    Othman, Norhayani; Noroozi, Nazbanoo; Jazrawi, Bashar; Mehrkhodavandi, Parisa; Schafer, Laurel; Hatzikiriakos, Savvas George

    2015-04-01

    The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) and poly(ɛ-caprolactone), (PCLs) have been investigated. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight consistent with wall slip data reported in the literature for other systems. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Similarly, sharkskin and gross melt fracture was observed for the case of PCLs depending on the molecular characteristics of the resins and the geometrical details of the capillary dies. It was also found that the addition of a small amount of PCL (typically 0.5 wt.%) into the PLA and vice versa is effective in eliminating and delaying the onset of melt fracture to higher shear rates in the capillary extrusion of PLA and PCL respectively. This is due to significant interfacial slip that occurs in the presence of PCL or PLA as well as to the immiscibility of the PLA/PCL blend system at all compositions.

  8. Path Following with Slip Compensation for a Mars Rover

    NASA Technical Reports Server (NTRS)

    Helmick, Daniel; Cheng, Yang; Clouse, Daniel; Matthies, Larry; Roumeliotis, Stergios

    2005-01-01

    A software system for autonomous operation of a Mars rover is composed of several key algorithms that enable the rover to accurately follow a designated path, compensate for slippage of its wheels on terrain, and reach intended goals. The techniques implemented by the algorithms are visual odometry, full vehicle kinematics, a Kalman filter, and path following with slip compensation. The visual-odometry algorithm tracks distinctive scene features in stereo imagery to estimate rover motion between successively acquired stereo image pairs, by use of a maximum-likelihood motion-estimation algorithm. The full-vehicle kinematics algorithm estimates motion, with a no-slip assumption, from measured wheel rates, steering angles, and angles of rockers and bogies in the rover suspension system. The Kalman filter merges data from an inertial measurement unit (IMU) and the visual-odometry algorithm. The merged estimate is then compared to the kinematic estimate to determine whether and how much slippage has occurred. The kinematic estimate is used to complement the Kalman-filter estimate if no statistically significant slippage has occurred. If slippage has occurred, then a slip vector is calculated by subtracting the current Kalman filter estimate from the kinematic estimate. This slip vector is then used, in conjunction with the inverse kinematics, to determine the wheel velocities and steering angles needed to compensate for slip and follow the desired path.

  9. The activation system EASY-2007

    NASA Astrophysics Data System (ADS)

    Forrest, R. A.; Kopecky, J.

    2009-04-01

    Safety and waste management of materials for ITER, IFMIF and future power plants require knowledge of the activation caused by irradiation with neutrons, or in the case of IFMIF, deuterons. The European Activation System has been developed for such calculations and a new version was released earlier this year. This contains a large amount of nuclear data in the European Activation File covering neutron-, deuteron- and proton-induced cross sections. These data are input to the FISPACT code for activation calculations. EASY-2007 is being validated using integral and differential measurements. However, only a minority of reactions have experimental support and a statistical method is described that can test the complete library. Importance diagrams are useful in finding the dominant nuclides formed following irradiation and the reactions responsible for their production. These diagrams now cover energies above 20 MeV and examples of new dominant nuclides and reactions relevant to IFMIF are given.

  10. Determining the causes of fault slip rate variability for Northern Apennine thrusts on intermediate timescales

    NASA Astrophysics Data System (ADS)

    Gunderson, K. L.; Anastasio, D. J.; Pazzaglia, F. J.

    2012-12-01

    Documenting fault slip rate variability on intermediate (10^4-10^5 yr) timescales is crucial for understanding the process-linkages of short-term (10^1-10^3 yr) and long-term (10^6 yr) patterns of deformation; however, the lack of long records of fault slip with 10^4-10^5 yr resolution presents a major barrier to understanding the underlying process responsible for slip rate variability at those timescales. Taking advantage of spectacular, continuous exposure of growth strata, we document 10^4-10^5 yr resolution records of unsteady fault slip for the past 3.0 myr for three unconnected, shallow blind thrust anticlines growing along the Northern Apennine mountain front, Italy. Fault slip rates for these thrusts were determined from progressive restorations of marine and continental growth strata deposited on the anticlinal limbs. These restorations were supported by subsurface corre-lations of the measured growth sections in order to constrain the fold geometries and kin-ematics. Magnetostratigraphy, cyclostratigraphy, cosmogenic radionuclide (CRN) burial dating, and optically stimulated luminescence (OSL) burial dating provided the high-resolution age models for the growth sections. Slip histories determined from our pro-gressive restorations indicate that all three of the thrust faults exhibited high-frequency slip rate variability. This variability is typically manifest by longer periods of decelerated fault slip punctuated by shorter periods of accelerated fault slip, typically lasting between 80-200 kyr. During times when slip rates were slow, growth strata geometries show ac-celerated slip was accommodated by more foreland structures, suggesting slip partitioning at 10^4-10^5 yr timescales. This high frequency variability is superimposed on a low frequency slip rate variability manifest by an overall deceleration in slip on the shallow thrusts since 3.0 myr. Major decelerations in slip rates were coincident with the activation of thick-skinned thrusting in the

  11. Evidence for 115 kilometers of right slip on the san gregorio-hosgri fault trend.

    PubMed

    Graham, S A; Dickinson, W R

    1978-01-13

    The San Gregorio-Hosgri fault trend is a component of the San Andreas fault system on which there may have been about 115 kilometers of post-early Miocene right-lateral strike slip. If so, right slip on the San Andreas and San Gregorio-Hosgri faults accounts for most of the movement between the Pacific and North American plates since mid-Miocene time. Furthermore, the magnitude of right slip on a Paleogene proto-San Andreas fault inferred from the present distribution of granitic basement is reduced considerably when Neogene-Recent San Gregorio-Hosgri right slip is taken into account. PMID:17812950

  12. Regional Slip Tendency Analysis of the Great Basin Region

    DOE Data Explorer

    Faulds, James E.

    2013-09-30

    are shown on Figure 3. For faults within the Great Basin proper, we applied a normal faulting stress regime, where the vertical stress (sv) is larger than the maximum horizontal stress (shmax), which is larger than the minimum horizontal stress (sv>shmax>shmin). Based on visual inspection of the limited stress magnitude data in the Great Basin, we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46. These values are consistent with stress magnitude data at both Dixie Valley (Hickman et al., 2000) and Yucca Mountain (Stock et al., 1985). For faults within the Walker Lane/Eastern California Shear Zone, we applied a strike‐slip faulting stress, where shmax > sv > shmin. Upon visual inspection of limited stress magnitude data from the Walker Lane and Eastern California Shear zone, we chose values such that SHmin/SHmax = .46 and Shmin/Sv= .527 representative of the region. Results: The results of our slip and dilation tendency analysis are shown in Figures 4 (dilation tendency), 5 (slip tendency) and 6 (slip tendency + dilation tendency). Shmin varies from northwest to east‐west trending throughout much of the Great Basin. As such, north‐ to northeast‐striking faults have the highest tendency to slip and to dilate, depending on the local trend of shmin. These results provide a first order filter on faults and fault systems in the Great Basin, affording focusing of local‐scale exploration efforts for blind or hidden geothermal resources.

  13. Reactivated strike slip faults: examples from north Cornwall, UK

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seog; Andrews, Jim R.; Sanderson, David J.

    2001-10-01

    smaller slip followed by larger slip with opposite sense, the d- x profile would be flatter with no reverse displacement at the tips. Reactivation also decreases the ratio of dmax/ L since for an original right-lateral fault, left lateral reactivation will reduce the net displacement ( dmax) along a fault and increase the fault length ( L). Finally we compare Crackington Haven faults with these in the Atacama system of northern Chile. The Salar Grande Fault (SGF) formed as a left-lateral fault with large displacement in its central region. Later right-lateral reactivation is preserved at the fault tips and at the smaller sub-parallel Cerro Chuculay Fault. These faults resemble those seen at Crackington Haven.

  14. Reassessing the 2006 Guerrero slow-slip event, Mexico: Implications for large earthquakes in the Guerrero Gap

    NASA Astrophysics Data System (ADS)

    Bekaert, D. P. S.; Hooper, A.; Wright, T. J.

    2015-02-01

    In Guerrero, Mexico, slow-slip events have been observed in a seismic gap, where no earthquakes have occurred since 1911. A rupture of the entire gap today could result in a Mw 8.2-8.4 earthquake. However, it remains unclear how slow-slip events change the stress field in the Guerrero seismic region and what their implications are for devastating earthquakes. Most earlier studies have relied on a sparse network of Global Navigation Satellite Systems measurements. Here we show that interferometric synthetic aperture radar can be used to improve the spatial resolution. We find that slip due to the 2006 slow-slip event enters the seismogenic zone and the Guerrero Gap, with ˜5 cm slip reaching depths as shallow as 12 km. We show that slow slip is correlated with a highly coupled region and estimate that slow-slip events have decreased the total accumulated moment since the end of the 2001/2002 slow-slip event (4.7 years) by ˜50%. Nevertheless, even accounting for slow slip, the moment deficit in the Guerrero Gap increases each year by Mw˜6.8. The Guerrero Gap therefore still has the potential for a large earthquake, with a slip deficit equivalent to Mw˜8.15 accumulated over the last century. Correlation between the slow-slip region and nonvolcanic tremor, and between slow slip and an ultraslow velocity layer, supports the hypothesis of a common source potentially related to high pore pressures.

  15. Multi-asperity models of slow slip and tremor

    NASA Astrophysics Data System (ADS)

    Ampuero, Jean Paul; Luo, Yingdi; Lengline, Olivier; Inbal, Asaf

    2016-04-01

    Field observations of exhumed faults indicate that fault zones can comprise mixtures of materials with different dominant deformation mechanisms, including contrasts in strength, frictional stability and hydrothermal transport properties. Computational modeling helps quantify the potential effects of fault zone heterogeneity on fault slip styles from seismic to aseismic slip, including slow slip and tremor phenomena, foreshocks sequences and swarms, high- and low-frequency radiation during large earthquakes. We will summarize results of ongoing modeling studies of slow slip and tremor in which fault zone structure comprises a collection of frictionally unstable patches capable of seismic slip (tremorgenic asperities) embedded in a frictionally stable matrix hosting aseismic transient slips. Such models are consistent with the current view that tremors result from repeated shear failure of multiple asperities as Low Frequency Earthquakes (LFEs). The collective behavior of asperities embedded in creeping faults generate a rich spectrum of tremor migration patterns, as observed in natural faults, whose seismicity rate, recurrence time and migration speed can be mechanically related to the underlying transient slow slip rate. Tremor activity and slow slip also responds to periodic loadings induced by tides or surface waves, and models relate tremor tidal sensitivity to frictional properties, fluid pressure and creep rate. The overall behavior of a heterogeneous fault is affected by structural parameters, such as the ratio of stable to unstable materials, but also by time-dependent variables, such as pore pressure and loading rate. Some behaviors are well predicted by homogenization theory based on spatially-averaged frictional properties, but others are somewhat unexpected, such as seismic slip behavior found in asperities that are much smaller than their nucleation size. Two end-member regimes are obtained in rate-and-state models with velocity-weakening asperities

  16. Fuzzy chaos control for vehicle lateral dynamics based on active suspension system

    NASA Astrophysics Data System (ADS)

    Huang, Chen; Chen, Long; Jiang, Haobin; Yuan, Chaochun; Xia, Tian

    2014-07-01

    The existing research of the active suspension system (ASS) mainly focuses on the different evaluation indexes and control strategies. Among the different components, the nonlinear characteristics of practical systems and control are usually not considered for vehicle lateral dynamics. But the vehicle model has some shortages on tyre model with side-slip angle, road adhesion coefficient, vertical load and velocity. In this paper, the nonlinear dynamic model of lateral system is considered and also the adaptive neural network of tire is introduced. By nonlinear analysis methods, such as the bifurcation diagram and Lyapunov exponent, it has shown that the lateral dynamics exhibits complicated motions with the forward speed. Then, a fuzzy control method is applied to the lateral system aiming to convert chaos into periodic motion using the linear-state feedback of an available lateral force with changing tire load. Finally, the rapid control prototyping is built to conduct the real vehicle test. By comparison of time response diagram, phase portraits and Lyapunov exponents at different work conditions, the results on step input and S-shaped road indicate that the slip angle and yaw velocity of lateral dynamics enter into stable domain and the results of test are consistent to the simulation and verified the correctness of simulation. And the Lyapunov exponents of the closed-loop system are becoming from positive to negative. This research proposes a fuzzy control method which has sufficient suppress chaotic motions as an effective active suspension system.

  17. Temperature dependence of atomic-scale stick-slip friction.

    PubMed

    Jansen, Lars; Hölscher, Hendrik; Fuchs, Harald; Schirmeisen, André

    2010-06-25

    We report experiments of atomic stick-slip friction on graphite as an explicit function of surface temperature between 100 and 300 K under ultrahigh vacuum conditions. A statistical analysis of the individual stick-slip events as a function of the velocity reveals an agreement with the thermally activated Prandtl-Tomlinson model at all temperatures. Taking into account an explicit temperature-dependence of the attempt frequency all data points collapse onto one single master curve. PMID:20867399

  18. Crustal earthquake instability in relation to the depth variation of frictional slip properties

    NASA Astrophysics Data System (ADS)

    Tse, Simon T.; Rice, James R.

    1986-08-01

    Recent stability studies using constitutive relations of the type found by Dieterich, Ruina, and others to describe frictional slip of rocks in the laboratory have provided a new explanation of the depth cutoff of shallow crustal earthquakes. The class of friction laws discussed has the property that the sliding stress depends on normal stress, temperature, slip rate, and slip history. For sliding at a fixed slip rate V and fixed environment (e.g., normal stress, temperature, etc.) the shear strength τ evolves toward a steady state value τss(V). Stability analysis show that for dτss(V)/dV < 0 (i.e., velocity weakening), steady state sliding is unstable to any perturbation in systems of sufficiently low stiffness and is unstable to sufficiently large perturbations in systems of higher stiffness. Hence a surface with dτss(V)/dV < 0 is potentially unstable. Conversely, dτss(V)/dV > 0 (velocity strengthening) implies stable steady state sliding, at least for a broad class of constitutive laws more fully described in the paper. Experiments by Dieterich and by Tullis and Weeks on Westerly granite with mature sliding surfaces indicate that dτss(V)/dV is negative at room temperature, whereas higher-temperature experiments by Stesky show that dτss(V)/dV becomes positive above approximately 300°C. Therefore, in the case of the earth, where temperature increases with depth, the above observations seem to suggest that the depth cutoff of crustal earthquake activity can be understood in terms of the variation of the frictional response with depth, from a regime with dτss(V)/dV < 0 to one with dτss(V)/dV > 0. This is not inconsistent with, but rather refines, the suggestion by Sibson and others that the depth cutoff is due to a transition from brittle friction to ductile flow. Further, our results show definitively that the shallow depth confinement of seismicity is compatible with a model in which deformation is localized to a fault zone extending well below the

  19. Nanocrystalline mirror-slip surfaces in calcite gouge sheared at sub-seismic slip rates

    NASA Astrophysics Data System (ADS)

    Verberne, B. A.; Plümper, O.; de Winter, D.; Niemeijer, A. R.; Spiers, C. J.

    2013-12-01

    conditions at sub-seismic sliding velocities, in velocity strengthening as well as velocity weakening samples. This means that their presence cannot be used as a single diagnostic indicator for seismic slip in natural fault rocks. Our SEM and TEM observations suggest that, at room temperature, the frictional behavior of the shear bands is dominated by crystal plastic plus nanogranular flow mechanisms, rather than by brittle deformation processes - as inferred for frictional slip in some metals. We further suggest that it is the thermally activated nature of crystal plasticity that is responsible for the transition from velocity strengthening to velocity weakening slip that we observed at ~80°C. The inferred mechanism has important implications for understanding both the depth range of seismicity and the seismic cycle in tectonically-active carbonate terrains.

  20. Frictional slip of granite at hydrothermal conditions

    USGS Publications Warehouse

    Blanpied, M.L.; Lockner, D.A.; Byerlee, J.D.

    1995-01-01

    To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, laboratory granite faults containing a layer of granite powder (simulated gouge) were slid. The mechanical results define two regimes. The first regime includes dry granite up to at least 845?? and wet granite below 250??C. In this regime the coefficient of friction is high (?? = 0.7 to 0.8) and depends only modestly on temperature, slip rate, and PH2O. The second regime includes wet granite above ~350??C. In this regime friction decreases considerably with increasing temperature (temperature weakening) and with decreasing slip rate (velocity strengthening). These regimes correspond well to those identified in sliding tests on ultrafine quartz. The results highlight the importance of fluid-assisted deformation processes active in faults at depth and the need for laboratory studies on the roles of additional factors such as fluid chemistry, large displacements, higher concentrations of phyllosilicates, and time-dependent fault healing. -from Authors

  1. Using a genetic algorithm to estimate the details of earthquake slip distributions from point surface displacements

    NASA Astrophysics Data System (ADS)

    Lindsay, A.; McCloskey, J.; Nic Bhloscaidh, M.

    2016-03-01

    Examining fault activity over several earthquake cycles is necessary for long-term modeling of the fault strain budget and stress state. While this requires knowledge of coseismic slip distributions for successive earthquakes along the fault, these exist only for the most recent events. However, overlying the Sunda Trench, sparsely distributed coral microatolls are sensitive to tectonically induced changes in relative sea levels and provide a century-spanning paleogeodetic and paleoseismic record. Here we present a new technique called the Genetic Algorithm Slip Estimator to constrain slip distributions from observed surface deformations of corals. We identify a suite of models consistent with the observations, and from them we compute an ensemble estimate of the causative slip. We systematically test our technique using synthetic data. Applying the technique to observed coral displacements for the 2005 Nias-Simeulue earthquake and 2007 Mentawai sequence, we reproduce key features of slip present in previously published inversions such as the magnitude and location of slip asperities. From the displacement data available for the 1797 and 1833 Mentawai earthquakes, we present slip estimates reproducing observed displacements. The areas of highest modeled slip in the paleoearthquake are nonoverlapping, and our solutions appear to tile the plate interface, complementing one another. This observation is supported by the complex rupture pattern of the 2007 Mentawai sequence, underlining the need to examine earthquake occurrence through long-term strain budget and stress modeling. Although developed to estimate earthquake slip, the technique is readily adaptable for a wider range of applications.

  2. How Orogen-scale Exhumed Strike-slip Faults Initiate

    NASA Astrophysics Data System (ADS)

    Cao, S.; Neubauer, F.

    2015-12-01

    Orogen-scale strike-slip faults present one the most important geodynamic processes affecting the lithosphere-asthenosphere system. In specific subtypes, faulting is virtually initiated along hot-to-cool boundaries, e.g. at such of hot granite intrusions or metamorphic core complexes to cool country rocks. Such fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust and are stacked within each other ("telescoping"). Exhumation of rocks is, therefore, a common feature of such strike-slip faults implying major transtensive and/or transpressive processes accompanying pure strike-slip motion. The hot-to-cool thermal structure across the fault zone significantly influences the physical fault rock properties. One major question is how and where a major strike-slip initiates and further development. Here, we propose a model in which major continental exhumed strike-slip faults potentially evolve along rheologically weak zones such as plutons or margins of metamorphic complexes. As an example, we propose a model for the Ailao Shan-Red River (ASRR) fault, SE Asia, which initiated along the edge of a plutonic belt and evolved in response to India-Asia collision with four tectonic phases.

  3. Using fault displacement and slip tendency to estimate stress states

    NASA Astrophysics Data System (ADS)

    Morris, Alan P.; Ferrill, David A.; McGinnis, Ronald N.

    2016-02-01

    We suggest that faults in high slip tendency orientations tend to develop larger displacements than other faults. Consequently, faults that accumulate larger displacements are more likely to be reliable indicators of the longer term stress field and should be weighted accordingly in paleostress estimation. Application of a stress inversion technique that uses slip tendency analyses and fault displacements to interpret populations of coherent normal faults within the Balcones Fault System of south-central Texas provides stress estimates that are consistent with established regional stress analyses. Although the method does not require measurement of slip directions, these data, where available, and sensitivity analyses of the angular mismatch between measured slip directions and those predicted by inverted stress states provide high confidence in the stress estimates generated using slip tendency analyses. Close inspection of the fault orientation and displacement data further indicates that subpopulations of faults with orientations different from the regional pattern have formed in response to stress perturbations generated by displacement gradients on an adjacent seismic scale fault.

  4. Stokes flow in a pipe with distributed regions of slip

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Stone, Howard A.

    2002-11-01

    Steady pressure-driven Stokes flow in a circular pipe is investigated analytically in the case where the pipe surface contains periodically distributed transverse regions of zero surface shear stress. One physical motivation for this problem is the recent experimental observation of nanobubbles on smooth hydrophobic surfaces (Ishida et al. (2000) Langmuir vol. 16, Tyrrell and Attard (2001) Phys. Rev. Lett. vol. 87) while a second motivation is the possible presence of bubbles trapped on rough surfaces. The bubbles may provide a zero shear stress boundary condition for the flow and modify considerably the friction generated by the solid boundary. In the spirit of experimental studies probing apparent slip at solid surfaces, the effective slip length of the resulting macroscopic flow is evaluated numerically and asymptotically as a function of the relative width of the no-slip and no-shear stress regions and their distribution along the pipe. Comparison of the model with experimental studies of pressure-driven flow in capillaries and microchannels is made and a possible interpretation of the results is offered which is consistent with a large number of nano-size and micron-size bubbles coating the solid surface. Finally, an explanation for the seemingly paradoxical behavior of the measured slip length increasing with system size reported by Watanabe et al. (1999) (J. Fluid Mech. vol. 381) is proposed and the possibility of a shear-dependent effective slip length is suggested.

  5. Imaging fault slip variation along the central San Andreas fault from satellite, airborne InSAR and GPS

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Lundgren, P.; Fielding, E. J.; Hensley, S.

    2011-12-01

    The improved spatiotemporal resolution of surface deformation from recent satellite and airborne InSAR measurements provides great potential to improve our understanding of faulting processes and earthquake hazard for a given fault system. A major plate boundary fault in central California, the central San Andreas fault (CSAF) displays a spectrum of complex fault slip behaviors with creeping in its central segment that decreases towards its northwest and southeast ends where the fault transitions to being locked. In the north the CSAF branches into two sub-parallel faults that are both actively accommodating plate motion. To the south, near the Parkfield transition, large earthquakes have occurred with at least six Mw ~6.0 events since 1857, most recently in 2004. To understand the complexity and variety of fault slip behaviors and fault mechanics, we integrate satellite and airborne synthetic aperture radar (SAR) repeat pass interferometry (RPI) observations, with GPS measurements from the Plate Boundary Observatory (PBO) and regional campaign networks to estimate fault slip and shallow slip deficits along the CSAF. Existing C-band ERS-1/2, Envisat and Radarsat SAR data provide long archives of SAR data over the region but are subject to severe decorrelation. The Japan Aerospace Exploration Agency's ALOS satellite has made less frequent acquisitions (5-6/yr per track) since 2006 but its PALSAR L-band sensor provides much improved coherence compared to shorter wavelength radar data. More recently, the NASA UAVSAR airborne SAR has repeated fault perpendicular adjacent swaths imaged from opposing look directions and fault parallel swath flights over the CSAF over the past three years and provides an improved imaging of fault slip related deformation at finer spatial resolution than previous platforms (~6m at 12 azimuth x 3 range looks). Compared to C-band instruments, the UAVSAR provides nearly complete spatial coverage. Compared to the ALOS mission, the UAVSAR

  6. Testing simple models of brittle normal faulting: slip rate, spacing, and segmentation

    NASA Astrophysics Data System (ADS)

    Connolly, J.; Dawers, N. H.

    2005-05-01

    Fault growth and evolution is a complex process, however any predictable pattern will yield important information for assessing seismic hazard and clues to what controls fault behavior. Models of slip rate variation along strike, spacing of active faults, and scaling of segment length are investigated using data from faults located within the parabola of seismicity around the Yellowstone hotspot. Based on displacement-length relations and segment size, Cowie and Roberts used fault geometry to estimate along-strike slip rate variation in their 2001 paper (JSG,23,1901-1915). Following their model, along-strike slip rate profiles were calculated for three active normal faults: the Beaverhead, Lemhi, and Lost River faults. Though the method yields estimated slip rates, the results roughly mirror along-strike variation in total displacement, because the three faults are similar in size and age. The profiles indicate that the Beaverhead is underdisplaced, i.e. having a low slip rate relative to its length. This suggests that segment linkage occurred later in the development of the Beaverhead than in the others. Cowie and Roberts also proposed a model for fault spacing based on initial fault length and spacing, and maximum length and spacing of fully developed fault systems. Fault spacing is important in determining incidence and magnitude of fault movement. If the distance between faults is too small, strain becomes localized along one while the other exhibits a decrease in seismicity until no activity occurs. In practice it is impossible to know if the distance between the largest faults represents maximum fault spacing, because the fault population is still active and evolving; thus, it is difficult to test or implement the method. A relationship was found among faults within the study area, where spacing of adjacent active faults is proportional to the sums of their lengths. It was also observed that average segment length increases with increasing total fault length

  7. Molecular scale simulation of homopolymer wall slip.

    PubMed

    Dorgan, John R; Rorrer, Nicholas A

    2013-04-26

    The first molecular scale simulation of highly entangled polydisperse homopolymers that is capable of capturing all three regions--no slip, weak slip, and strong slip--of the hydrodynamic boundary condition is presented. An on-lattice dynamic Monte Carlo technique capable of correctly capturing both unentangled and entangled polymer dynamics is used to study the molecular details of wall slip phenomena for homopolymers and energetically neutral walls. For unentangled chains (those exhibiting Rouse dynamics) weak slip is not present but evidence of strong slip is manifest at very high shear rates. For entangled chains (of sufficient length to exhibit reptation dynamics), both weak and strong slip are observed. Consistent with numerous experimental studies, disentanglement and cohesive failure occur at high shear rates. Disentanglement is clearly evidenced in a nonlinear velocity profile that exhibits shear banding, in an excess of chain ends at the slip plane, and perhaps most importantly in a nonmonotonic stress versus shear rate response. The chain end density exhibits a pretransitional periodicity prior to disentanglement. Unentangled Rouse chains do not show this pretransitional response or a bifurcation in their stress versus shear rate response. Finally, it is shown that when polydispersity is introduced, slip phenomena are severely reduced and the inherent constitutive bifurcation is limited to a small region. Predictions are in post facto agreement with many experiments, are distinct from existing results obtained using molecular dynamics simulation techniques, and shed light on fundamental mechanisms of polymer wall slip. PMID:23679746

  8. The distribution and characterization of strike-slip faults on Enceladus

    NASA Astrophysics Data System (ADS)

    Martin, Emily S.

    2016-03-01

    Strike-slip faulting is typically characterized by lateral offsets on icy satellites of the outer solar system. However, strike-slip faults on Enceladus lack these typical lateral offsets and instead are marked by the presence of tailcracks or en echelon cracks. These features are used here to develop the first near-global distribution of strike-slip faults on Enceladus. Strike-slip faults on Enceladus fall into three broad categories: tectonic terrain boundaries, reactivated linear features, and primary strike-slip faults. All three types of strike-slip faults are found predominantly, or within close proximity to, the antipodal cratered terrains on the Saturnian and anti-Saturnian hemispheres. Stress modeling suggests that strike-slip faulting on Enceladus is not controlled by nonsynchronous rotation, as on Europa, suggesting a fundamentally different process driving Enceladus's strike-slip faulting. The motion along strike-slip faults at tectonic terrain boundaries suggests large-scale northward migration of the ice shell on the leading hemisphere of Enceladus, occurring perpendicular to the opening direction of the tiger stripes in the south polar terrain.

  9. Slip mode segmentation of the megathrust beneath Nicoya Peninsula, Costa Rica

    NASA Astrophysics Data System (ADS)

    Voss, Nick; Malservisi, Rocco; Liu, Zhen; Dixon, Timothy H.; Protti, Marino; Gonzales, Victor; Schwartz, Susan; Jiang, Yan

    2016-04-01

    The Nicoya Peninsula, Costa Rica, overlies a section of a subduction megathrust close to the Middle America Trench. This location allows terrestrial geodetic monitoring of the surface deformation above the seismogenic zone, a region that is often underwater in many subduction zones. A continuous Global Positioning System network has operated in the Nicoya peninsula of northern Costa Rica since 2002 observing a number of deep and shallow slow slip events (SSEs) with a recurrence interval of ~21 months. On September 5th 2012, a Mw 7.6 nucleated just underneath the geodetic network. We explore the relationship between these recurrent SSEs and the large earthquake. We find that SSE recurrence interval appears constant before and after the earthquake. Using a modified version of the Extended Network Inversion Filter [e.g. McGuire and Segall, 2003] (ENIF) to identify time dependent characteristics of SSEs before and after the 2012 Nicoya earthquake, we find that slip starts updip prior to the earthquake in the shallow, 15 km depth, section of the subduction zone and then migrates to a deep patch beneath the Nicoya gulf. Following the earthquake, high slip rates initiate down dip (40 km depth) and remain downdip, a change from observations of SSEs prior to the earthquake. In this study, we also analyze the temporal and spatial evolution of the surface deformation at different temporal scales (from hours to years) after the earthquake to infer the aseismic slip due to postsiesmic response on the fault interface. We compare the portion of postseismic displacement interpreted as afterslip with our previous analysis of SSE. Our results show that the main rupture was followed by significant early afterslip for the first 3 hours after the main event followed by regular afterslip decaying exponentially. During the first few months, the afterslip has most likely filled gaps left by the coseismic rupture (in particular updip). We also show that afterslip seems to be bounded by

  10. Termination of major strike-slip faults against thrust faults in a syntaxis, as interpreted from landsat images

    SciTech Connect

    Iranpanah, A.

    1988-01-01

    The north to northeast-striking Minab fault (Zendan fault) in western Makran, Iran, is interpreted as an intracontinental transform structure that separates, along its length, the Zagros foldbelt from the Makran active trench-arc system. The 200-km long fault has a right-lateral strike-slip component and is terminated at its northern end by the north-northwest and northwest-striking Zagros main thrust. The Minab transform zone delimits the western margin of the Makran convergence zone where an oceanic part of the Afro-Arabian lithosphere is being subducted beneath the Lut and Afghan microplates. A northern extension of the Minab transform zone terminates at an internal convergence boundary within the Bandar Abbas-Minab syntaxis. The Minab transform fault consists of a zone of generally north-northwest-trending thombic conjugate strike-slip faults. The pattern of faulting for the Minab strike-slip fault zone, when traced over the entire area on the Landsat image, shows that areas with rhombic sets of conjugate strike-slip faults are separated by a few areas showing only extensional zones. This is compatible with the traditionally idealized reverse-S pattern for the strike-slip faults reported from the United States Basin and Range province. The mechanical explanation for the rhombic pattern of the fault system is consistent with the same pattern and motion as currently exists in the Makran accretionary belt. The origin of the Bandar Abbas-Minab syntaxis is believed to be related to convergence between the Afro-Arabian plate and the Lut and Afghan microplates. The convergence zone is a well-developed trench-arc gap. The western edge of this trench-arc system has been dragged to the north along the Minab dextral fault zone. This zone, which started developing in the Late Cretaceous-Paleocene, is directly responsible for the development of the Bandar Abbas-Minab syntaxis.

  11. Strike-slip faulting in the Inner California Borderlands, offshore Southern California.

    NASA Astrophysics Data System (ADS)

    Bormann, J. M.; Kent, G. M.; Driscoll, N. W.; Harding, A. J.; Sahakian, V. J.; Holmes, J. J.; Klotsko, S.; Kell, A. M.; Wesnousky, S. G.

    2015-12-01

    In the Inner California Borderlands (ICB), offshore of Southern California, modern dextral strike-slip faulting overprints a prominent system of basins and ridges formed during plate boundary reorganization 30-15 Ma. Geodetic data indicate faults in the ICB accommodate 6-8 mm/yr of Pacific-North American plate boundary deformation; however, the hazard posed by the ICB faults is poorly understood due to unknown fault geometry and loosely constrained slip rates. We present observations from high-resolution and reprocessed legacy 2D multichannel seismic (MCS) reflection datasets and multibeam bathymetry to constrain the modern fault architecture and tectonic evolution of the ICB. We use a sequence stratigraphy approach to identify discrete episodes of deformation in the MCS data and present the results of our mapping in a regional fault model that distinguishes active faults from relict structures. Significant differences exist between our model of modern ICB deformation and existing models. From east to west, the major active faults are the Newport-Inglewood/Rose Canyon, Palos Verdes, San Diego Trough, and San Clemente fault zones. Localized deformation on the continental slope along the San Mateo, San Onofre, and Carlsbad trends results from geometrical complexities in the dextral fault system. Undeformed early to mid-Pleistocene age sediments onlap and overlie deformation associated with the northern Coronado Bank fault (CBF) and the breakaway zone of the purported Oceanside Blind Thrust. Therefore, we interpret the northern CBF to be inactive, and slip rate estimates based on linkage with the Holocene active Palos Verdes fault are unwarranted. In the western ICB, the San Diego Trough fault (SDTF) and San Clemente fault have robust linear geomorphic expression, which suggests that these faults may accommodate a significant portion of modern ICB slip in a westward temporal migration of slip. The SDTF offsets young sediments between the US/Mexico border and the

  12. Process for slip casting textured tubular structures

    DOEpatents

    Steinlage, Greg A.; Trumble, Kevin P.; Bowman, Keith J.

    2002-01-01

    A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

  13. Multicycle slip distribution along a laboratory fault

    USGS Publications Warehouse

    Chi-Yu, King

    1991-01-01

    Slip distribution along a laboratory fault, which consists of eight spring-connected blocks that are elastically driven to slide on a frictional surface, has been examined for a "long' sequence of slip events to test the applicability of some conceptual models. The distributions of large slip events are found to be quite variable and do not fit the uniform slip or characteristic earthquake models. The rupture initiation points are usually not near the corresponding maximum slip points, in contrast to observations by Thatcher (1990) and by Fukao and Kikuchi (1987) that earthquake hypocenters are commonly near corresponding regions of maximum slip in the fault planes. The results suggest that earthquake prediction monitoring efforts should not be limited to a small region near an asperity but should be spread out to cover the entire fault segment in a seismic gap in order to detect the condition of simultaneous strain buildup. -from Author

  14. Three dimensional surface slip partitioning of the Sichuan earthquake from Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    de Michele, M.; Raucoules, D.; de Sigoyer, J.; Pubellier, M.; Lasserre, C.; Pathier, E.; Klinger, Y.; van der Woerd, J.

    2009-12-01

    The Sichuan earthquake, Mw 7.9, struck the Longmen Shan range front, in the western Sichuan province, China, on 12 May 2008. It severely affected an area where little historical seismicity and little or no significant active shortening were reported before the earthquake (e.g. Gu et al., 1989; Chen et al., 1994; Gan et al., 2007). The Longmen Shan thrust system bounds the eastern margin of the Tibetan plateau and is considered as a transpressive zone since Triassic time that was reactivated during the India-Asia collision (e.g., Tapponnier and Molnar, 1977, Chen and Wilson 1996; Arne et al., 1997, Godard et al., 2009). However, contrasting geological evidences of sparse thrusting and marked dextral strike-slip faulting during the Quaternary along with high topography (Burchfiel et al., 1995; Densmore et al., 2007) have led to models of dynamically driven and sustained topography (Royden et al., 1997) limiting the role of earthquakes in relief building and leaving the mechanism of long term strain distribution in this area as an open question. Here we combine C and L band Synthetic Aperture Radar (SAR) offsets data from ascending and descending paths to retrieve the three dimensional surface slips distribution all along the earthquake ruptures of the Sichuan earthquake. We show a quantitative assessment of the amount of co-seismic slip and its partitioning at the surface.

  15. Rupture of multiple catch-slip bonds: Two-state two-pathway catch-slip bonds.

    PubMed

    Gupta, V K

    2013-11-01

    We performed Monte Carlo simulation of the detachment of a polymorphonuclear (PMN) leukocyte immersed in a Newtonian fluid and adhered to a substrate by multiple catch-slip bonds. We found that at certain loading rates the interplay of multiple catch-slip bonds leads to a bimodal distribution of the bond rupture force. We also found that the low force peak in these bond rupture force distributions switches to a high force peak with a gradual increase in the loading rate. These trends in the bond rupture force distributions are characteristics of two-state systems. Consequently, though individual catch-slip bonds follow one-state two-pathway energy landscape, their interplay mimics a two-state two-pathway energy landscape. PMID:24272665

  16. Cumulative right-lateral fault slip rate across the Zagros-Makran transfer zone: role of the Minab-Zendan fault system in accommodating Arabia-Eurasia convergence in southeast Iran

    NASA Astrophysics Data System (ADS)

    Regard, V.; Bellier, O.; Thomas, J.-C.; Bourlès, D.; Bonnet, S.; Abbassi, M. R.; Braucher, R.; Mercier, J.; Shabanian, E.; Soleymani, Sh.; Feghhi, Kh.

    2005-07-01

    The Zendan-Minab zone is the transition zone between the Zagros collision to the west and Makran subduction to the east. It is also linked to the north with the Nayband-Gowk fault system that bounds the Lut Block to the east. The total convergence rate between Arabia and Eurasia is estimated to range between 23 and 35 mm yr-1 in a NNE-trending direction. The deformation through the Minab-Zendan system is accommodated within two fault systems, the western N160°E-trending Minab-Zendan fault system and the eastern north-south Sabzevaran-Jiroft fault system. The study area is characterized by a well-defined succession of Quaternary deposit levels. The age of these deposits was estimated by archaeological data, regional palaeoclimate correlations and constrained by additional in situ10Be dating in another paper in this study. These deposits exhibit offsets, both lateral and vertical, that are evaluated by satellite image analysis and GPS profiles. Thanks to offsets and ages the strike-slip rates associated with the Minab-Zendan and the Sabzevaran-Jiroft fault systems are calculated to be 5.1 +/- 1.3 or 6.6 +/- 1.5, and 6.2 +/- 0.7 mm yr-1, respectively. These results allow an evaluation of the velocity vector of the Musandam Peninsula (Oman) with respect to the Lut Block of 11.4 +/- 2.0 or 12.9 +/- 2.2 mm yr-1 in a N10 +/- 15°E direction, close to the GPS estimates. This study also constrains the in-plane slip rates for each fault. Previous works indicate that the Zagros accommodates only 10 mm yr-1 of shortening, while 10 mm yr-1 should be accommodated by the Alborz mountains in northern Iran. This last 10 mm yr-1 may be accommodated through the Nayband-Gowk system and the East Iranian ranges, implying that the two fault systems constituting the Zagros-Makran transfer zone have different geodynamic roles. The western Minab-Zendan fault system links the Makran and Zagros deforming zones, whereas the northwestern Jiroft-Sabzevaran fault system is transmitting the

  17. Phase-field slip-line theory of plasticity

    NASA Astrophysics Data System (ADS)

    Freddi, Francesco; Royer-Carfagni, Gianni

    2016-09-01

    A variational approach to determine the deformation of an ideally plastic substance is proposed by solving a sequence of energy minimization problems under proper conditions to account for the irreversible character of plasticity. The flow is driven by the local transformation of elastic strain energy into plastic work on slip surfaces, once that a certain energetic barrier for slip activation has been overcome. The distinction of the elastic strain energy into spherical and deviatoric parts is used to incorporate in the model the idea of von Mises plasticity and isochoric plastic strain. This is a "phase field model" because the matching condition at the slip interfaces is substituted by the evolution of an auxiliary phase field that, similar to a damage field, is unitary on the elastic phase and null on the yielded phase. The slip lines diffuse in bands, whose width depends upon a material length-scale parameter. Numerical experiments on representative problems in plane strain give solutions with noteworthy similarities with the results from classical slip-line field theory, but the proposed model is much richer because, accounting for elastic deformations, it can describe the formation of slip bands at the local level, which can nucleate, propagate, widen and diffuse by varying the boundary conditions. In particular, the solution for a long pipe under internal pressure is very different from the one obtainable from the classical macroscopic theory of plasticity. For this case, the location of the plastic bands may be an insight to explain the premature failures that are sometimes encountered during the manufacturing process. This practical example enhances the importance of this new theory based on the mathematical sciences.

  18. Learning to predict slip for ground robots

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Matthies, Larry; Helmick, Daniel; Sibley, Gabe; Perona, Pietro

    2006-01-01

    In this paper we predict the amount of slip an exploration rover would experience using stereo imagery by learning from previous examples of traversing similar terrain. To do that, the information of terrain appearance and geometry regarding some location is correlated to the slip measured by the rover while this location is being traversed. This relationship is learned from previous experience, so slip can be predicted later at a distance from visual information only.

  19. Fault slip distribution and fault roughness

    NASA Astrophysics Data System (ADS)

    Candela, Thibault; Renard, François; Schmittbuhl, Jean; Bouchon, Michel; Brodsky, Emily E.

    2011-11-01

    We present analysis of the spatial correlations of seismological slip maps and fault topography roughness, illuminating their identical self-affine exponent. Though the complexity of the coseismic spatial slip distribution can be intuitively associated with geometrical or stress heterogeneities along the fault surface, this has never been demonstrated. Based on new measurements of fault surface topography and on statistical analyses of kinematic inversions of slip maps, we propose a model, which quantitatively characterizes the link between slip distribution and fault surface roughness. Our approach can be divided into two complementary steps: (i) Using a numerical computation, we estimate the influence of fault roughness on the frictional strength (pre-stress). We model a fault as a rough interface where elastic asperities are squeezed. The Hurst exponent ?, characterizing the self-affinity of the frictional strength field, approaches ?, where ? is the roughness exponent of the fault surface in the direction of slip. (ii) Using a quasi-static model of fault propagation, which includes the effect of long-range elastic interactions and spatial correlations in the frictional strength, the spatial slip correlation is observed to scale as ?, where ? represents the Hurst exponent of the slip distribution. Under the assumption that the origin of the spatial fluctuations in frictional strength along faults is the elastic squeeze of fault asperities, we show that self-affine geometrical properties of fault surface roughness control slip correlations and that ?. Given that ? for a wide range of faults (various accumulated displacement, host rock and slip movement), we predict that ?. Even if our quasi-static fault model is more relevant for creeping faults, the spatial slip correlations observed are consistent with those of seismological slip maps. A consequence is that the self-affinity property of slip roughness may be explained by fault geometry without considering

  20. Active tectonics of the Andes

    NASA Astrophysics Data System (ADS)

    Dewey, J. F.; Lamb, S. H.

    1992-04-01

    Nearly 90 mm a -1 of relative plate convergence is absorbed in the Andean plate-boundary zone. The pattern of active tectonics shows remarkable variations in the way in which the plate slip vector is partitioned into displacement and strain and the ways in which compatibility between different segments is solved. Along any traverse across the plate-boundary zone, the sum of relative velocities between points must equal the relative plate motion. We have developed a kinematic synthesis of displacement and strain partitioning in the Andes from 47°S to 5°N relevant for the last 5 Ma based upon: (1) relative plate motion deduced from oceanic circuits giving a roughly constant azimuth between 075 and 080; (2) moment tensor solutions for over 120 crustal earthquakes since 1960; (3) structural studies of deformed Plio-Pleistocene rocks; (4) topographic/geomorphic studies; (5) palaeomagnetic data; and (6) geodetic data. We recognize four neotectonic zones, with subzones and boundary transfer zones, that are partitioned in different ways. These zones are not coincident with the 'classic' zones defined by the presence or absence of a volcanic chain or differences in finite displacements and strains and tectonic form; the long-term segmentation and finite evolution of the Andes may not occur in constantly defined segments in space and time. In Segment 1 (47°-39°S), the slip vector is partitioned into roughly orthogonal Benioff Zone slip with large magnitude/large slip-surface earthquakes and both distributed dextral shear giving clockwise rotations of up to 50° and dextral slip in the curved Liquine-Ofqui Fault System giving 5°-10° of anticlockwise fore-arc rotation. In Segment 2 (39°-20°S), the slip vector is partitioned into Benioff Zone slip roughly parallel with the slip vector, Andean crustal shortening and a very small component of dextral slip, including that on the Atacama Fault System. Between 39° and 34°S, a cross-strike dextral transfer, which deflects

  1. The slipping rib syndrome: A case report

    PubMed Central

    van Delft, E.A.K.; van Pul, K.M.; Bloemers, F.W.

    2016-01-01

    We present a case report and review of literature about slipping rib syndrome, a syndrome rarely recognized and often un or misdiagnosed. In literature there is no clear consensus about the diagnosis and treatment. We present a case of a 47 year old man who was diagnosed with slipping rib syndrome after a cycling incident 8 years ago. Also, we developed a flow chart according the diagnostic and therapeutic steps in the treatment of slipping rib syndrome. Central massage Knowledge and treatment of the slipping rib syndrome can prevent chronic complaints and unnecessary comprehensive treatment. PMID:27082995

  2. Molecular Scale Simulation of Homopolymer Wall Slip

    NASA Astrophysics Data System (ADS)

    Dorgan, John R.; Rorrer, Nicholas A.

    2013-04-01

    The first molecular scale simulation of highly entangled polydisperse homopolymers that is capable of capturing all three regions—no slip, weak slip, and strong slip—of the hydrodynamic boundary condition is presented. An on-lattice dynamic Monte Carlo technique capable of correctly capturing both unentangled and entangled polymer dynamics is used to study the molecular details of wall slip phenomena for homopolymers and energetically neutral walls. For unentangled chains (those exhibiting Rouse dynamics) weak slip is not present but evidence of strong slip is manifest at very high shear rates. For entangled chains (of sufficient length to exhibit reptation dynamics), both weak and strong slip are observed. Consistent with numerous experimental studies, disentanglement and cohesive failure occur at high shear rates. Disentanglement is clearly evidenced in a nonlinear velocity profile that exhibits shear banding, in an excess of chain ends at the slip plane, and perhaps most importantly in a nonmonotonic stress versus shear rate response. The chain end density exhibits a pretransitional periodicity prior to disentanglement. Unentangled Rouse chains do not show this pretransitional response or a bifurcation in their stress versus shear rate response. Finally, it is shown that when polydispersity is introduced, slip phenomena are severely reduced and the inherent constitutive bifurcation is limited to a small region. Predictions are in post facto agreement with many experiments, are distinct from existing results obtained using molecular dynamics simulation techniques, and shed light on fundamental mechanisms of polymer wall slip.

  3. Adaptive regularization of earthquake slip distribution inversion

    NASA Astrophysics Data System (ADS)

    Wang, Chisheng; Ding, Xiaoli; Li, Qingquan; Shan, Xinjian; Zhu, Jiasong; Guo, Bo; Liu, Peng

    2016-04-01

    Regularization is a routine approach used in earthquake slip distribution inversion to avoid numerically abnormal solutions. To date, most slip inversion studies have imposed uniform regularization on all the fault patches. However, adaptive regularization, where each retrieved parameter is regularized differently, has exhibited better performances in other research fields such as image restoration. In this paper, we implement an investigation into adaptive regularization for earthquake slip distribution inversion. It is found that adaptive regularization can achieve a significantly smaller mean square error (MSE) than uniform regularization, if it is set properly. We propose an adaptive regularization method based on weighted total least squares (WTLS). This approach assumes that errors exist in both the regularization matrix and observation, and an iterative algorithm is used to solve the solution. A weight coefficient is used to balance the regularization matrix residual and the observation residual. An experiment using four slip patterns was carried out to validate the proposed method. The results show that the proposed regularization method can derive a smaller MSE than uniform regularization and resolution-based adaptive regularization, and the improvement in MSE is more significant for slip patterns with low-resolution slip patches. In this paper, we apply the proposed regularization method to study the slip distribution of the 2011 Mw 9.0 Tohoku earthquake. The retrieved slip distribution is less smooth and more detailed than the one retrieved with the uniform regularization method, and is closer to the existing slip model from joint inversion of the geodetic and seismic data.

  4. Observation of slip flow in thermophoresis.

    PubMed

    Weinert, Franz M; Braun, Dieter

    2008-10-17

    Two differing theories aim to describe fluidic thermophoresis, the movement of particles along a temperature gradient. While thermodynamic approaches rely on local equilibrium, hydrodynamic descriptions assume a quasi-slip-flow boundary condition at the particle's surface. Evidence for slip flow is presented for the case of thermal gradients exceeding (aS_(T)(-1) with particle radius a and Soret coefficient S_(T). Thermophoretic slip flow at spheres near a surface attracts or repels tracer particles perpendicular to the thermal gradient. Moreover, particles mutually attract and form colloidal crystals. Fluid dynamic slip explains the latter quantitatively. PMID:18999718

  5. Development of a liquid metal slip ring

    NASA Technical Reports Server (NTRS)

    Weinberger, S. M.

    1972-01-01

    A liquid metal slip ring/solar orientation mechanism was designed and a model tested. This was a follow-up of previous efforts for the development of a gallium liquid metal slip ring in which the major problem was the formation and ejection of debris. A number of slip ring design approaches were studied. The probe design concept was fully implemented with detail drawings and a model was successfully tested for dielectric strength, shock vibration, acceleration and operation. The conclusions are that a gallium liquid metal slip ring/solar orientation mechanism is feasible and that the problem of debris formation and ejection has been successfully solved.

  6. Comparison of GPS and Quaternary slip rates: Insights from a new Quaternary fault database for Central Asia

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd; Bendick, Rebecca; Mutz, Sebastian

    2016-04-01

    Previous studies related to the kinematics of deformation within the India-Asia collision zone have relied on slip rate data for major active faults to test kinematic models that explain the deformation of the region. The slip rate data, however, are generally disputed for many of the first-order faults in the region (e.g., Altyn Tagh and Karakorum faults). Several studies have also challenged the common assumption that geodetic slip rates are representative of Quaternary slip rates. What has received little attention is the degree to which geodetic slip rates relate to Quaternary slip rates for active faults in the India-Asia collision zone. In this study, we utilize slip rate data from a new Quaternary fault database for Central Asia to determine the overall relationship between Quaternary and GPS-derived slip rates for 18 faults. The preliminary analysis investigating this relationship uses weighted least squares and a re-sampling analysis to test the sensitivity of this relationship to different data point attributes (e.g., faults associated with data points and dating methods used for estimating Quaternary slip rates). The resulting sample subsets of data points yield a maximum possible Pearson correlation coefficient of ~0.6, suggesting moderate correlation between Quaternary and GPS-derived slip rates for some faults (e.g., Kunlun and Longmen Shan faults). Faults with poorly correlated Quaternary and GPS-derived slip rates were identified and dating methods used for the Quaternary slip rates were examined. Results indicate that a poor correlation between Quaternary and GPS-derived slip rates exist for the Karakorum and Chaman faults. Large differences between Quaternary and GPS slip rates for these faults appear to be connected to qualitative dating of landforms used in the estimation of the Quaternary slip rates and errors in the geomorphic and structural reconstruction of offset landforms (e.g., offset terrace riser reconstructions for Altyn Tagh fault

  7. On the transient behavior of frictional melt during seismic slip

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; Mosca, P.; Giberti, G.; di Toro, G.; Hirose, T.; Shimamoto, T.

    2010-10-01

    In a recent work on the problem of sliding surfaces under the presence of frictional melt (applying in particular to earthquake fault dynamics), we derived from first principles an expression for the steady state friction compatible with experimental observations. Building on the expressions of heat and mass balance obtained in the above study for this particular case of Stefan problem (phase transition with a migrating boundary), we propose here an extension providing a full time-dependent solution (including the weakening transient after pervasive melting has started, the effect of eventual steps in velocity, and the final decelerating phase). A system of coupled equations is derived and solved numerically. The resulting transient friction and wear evolution yield a satisfactory fit (1) with experiments performed under variable sliding velocities (0.9-2 m s-1) and different normal stresses (0.5-20 MPa) for various rock types and (2) with estimates of slip weakening obtained from observations on ancient seismogenic faults that host pseudotachylite (solidified melt). The model allows us to extrapolate the experimentally observed frictional behavior to large normal stresses representative of the seismogenic Earth crust (up to 200 MPa), high slip rates (up to 9 m s-1), and cases where melt extrusion is negligible. Though weakening distance and peak stress vary widely, the net breakdown energy appears to be essentially independent of either slip velocity or normal stress. In addition, the response to earthquakelike slip can be simulated, showing a rapid friction recovery when slip rate drops. We discuss the properties of energy dissipation, transient duration, velocity weakening, restrengthening in the decelerating final slip phase, and the implications for earthquake source dynamics.

  8. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation

    PubMed Central

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-01-01

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm. PMID:26437412

  9. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation.

    PubMed

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-01-01

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm. PMID:26437412

  10. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Cortés, José M.; Terrizzano, Carla M.

    2016-05-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to ~450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  11. Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance.

    PubMed

    Wetzel, Christoph; Windhövel, Ulrich; Mewes, Detlef; Ceylan, Orhan

    2015-01-01

    Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field. PMID:26414511

  12. An analysis of the slip of screw dislocations in L1{sub 2} alloys

    SciTech Connect

    Veyssiere, P.

    1997-12-31

    The annihilation of dislocations by cross-slip is studied by numerical simulation of infinitely long dissociated screw dislocations, allowed to move in an elastically anisotropic crystal. The external load is along [{bar 1}23] and cross-slip is permitted both on the octahedral and on the cube plane. The latter, together with cube slip, is thermally activated. Anisotropic elasticity modifies the properties of cross-slip significantly. Under the conditions of the simulations, the processes of APB jumps (APBJs) and repeated APB jumps (RAPBJs) can be largely promoted by interactions with other dislocations, while it is much less likely to occur at an isolated dislocation submitted to the same applied stress. The encounter of dislocations of opposite signs produces dipoles which may or may not tend to annihilate by cross-slip. APB tubes may form upon annihilation under certain circumstances again largely controlled by elastic anisotropy.

  13. Active thermal control system evolution

    NASA Technical Reports Server (NTRS)

    Petete, Patricia A.; Ames, Brian E.

    1991-01-01

    The 'restructured' baseline of the Space Station Freedom (SSF) has eliminated many of the growth options for the Active Thermal Control System (ATCS). Modular addition of baseline technology to increase heat rejection will be extremely difficult. The system design and the available real estate no longer accommodate this type of growth. As the station matures during its thirty years of operation, a demand of up to 165 kW of heat rejection can be expected. The baseline configuration will be able to provide 82.5 kW at Eight Manned Crew Capability (EMCC). The growth paths necessary to reach 165 kW have been identified. Doubling the heat rejection capability of SSF will require either the modification of existing radiator wings or the attachment of growth structure to the baseline truss for growth radiator wing placement. Radiator performance can be improved by enlarging the surface area or by boosting the operating temperature with a heat pump. The optimal solution will require both modifications. The addition of growth structure would permit the addition of a parallel ATCS using baseline technology. This growth system would simplify integration. The feasibility of incorporating these growth options to improve the heat rejection capacity of SSF is under evaluation.

  14. Rolling and slipping motion of Euler's disk

    NASA Astrophysics Data System (ADS)

    Caps, H.; Dorbolo, S.; Ponte, S.; Croisier, H.; Vandewalle, N.

    2004-05-01

    We present an experimental study of the motion of a circular disk spun onto a table. With the help of a high speed video system, the temporal evolution of (i) the inclination angle α , (ii) the angular velocity ω , and (iii) the precession rate Ω are studied. The influence of the mass of the disk as well as the friction between the disk and the supporting surface are considered. Both inclination angle and angular velocity are observed to decrease according to a power law. We also show that the precession rate diverges as the motion stops. Measurements are performed very near the collapse as well as on long range times. Times to collapse have been also measured. Results are compared with previous theoretical and experimental works. The major source of energy dissipation is found to be the slipping of the disk on the plane.

  15. Inverse Slip Accompanying Twinning and Detwinning during Cyclic Loading of Magnesium Single Crystal

    DOE PAGESBeta

    Yu, Qin; Wang, Jian; Jiang, Yanyao

    2013-01-01

    In situ , observation of twinning and detwinning in magnesium single crystals during tension-compression cyclic loading was made using optical microscopy. A quantitative analysis of plastic strain indicates that twinning and detwinning experience two stages, low and high work hardening de-twinning, and pure re-twinning and fresh twinning combined with retwinning. Slip is always activated. For the first time, inverse slip accompanying with pure retwinning and high work hardening detwinning was experimentally identified, which provides insights in better understanding of the activity of twining, detwinning, and slips.

  16. Environmental study of miniature slip rings

    NASA Technical Reports Server (NTRS)

    Radnik, J. L.

    1967-01-01

    Investigation studied the long term operation of miniature slip ring assembles in high vacuum of space and included the influence of ring, brush, and insulator materials on electrical noise and mechanical wear. Results show that soft metal vapor plating and niobium diselenide miniature slip rings are beneficial.

  17. Unified slip boundary condition for fluid flows.

    PubMed

    Thalakkottor, Joseph John; Mohseni, Kamran

    2016-08-01

    Determining the correct matching boundary condition is fundamental to our understanding of several everyday problems. Despite over a century of scientific work, existing velocity boundary conditions are unable to consistently explain and capture the complete physics associated with certain common but complex problems, such as moving contact lines and corner flows. The widely used Maxwell and Navier slip boundary conditions make an implicit assumption that velocity varies only in the wall normal direction. This makes their boundary condition inapplicable in the vicinity of contact lines and corner points, where velocity gradient exists both in the wall normal and wall tangential directions. In this paper, by identifying this implicit assumption we are able to extend Maxwell's slip model. Here, we present a generalized velocity boundary condition that shows that slip velocity is a function of not only the shear rate but also the linear strain rate. In addition, we present a universal relation for slip length, which shows that, for a general flow, slip length is a function of the principal strain rate. The universal relation for slip length along with the generalized velocity boundary condition provides a unified slip boundary condition to model a wide range of steady Newtonian fluid flows. We validate the unified slip boundary for simple Newtonian liquids by using molecular dynamics simulations and studying both the moving contact line and corner flow problems. PMID:27627398

  18. One-dimensional dynamic simulations of slip complexity of earthquake faults

    NASA Astrophysics Data System (ADS)

    Wang, J.-H.; Hwang, R.-D.

    2001-02-01

    Slip complexity of earthquake faults is studied based on an N-degree-of-freedom dynamical spring-slider system in the presence of slip-law-type, velocity- and state-dependent friction. Simulation results based on such a friction law show that slip complexity depends on the inhomogeneous distribution of the breaking strengths (including its pattern and degree) along the fault and nonlinear velocity- and state-dependent friction. However, for the given model parameters the former is more important than the latter in controlling slip complexity. Frictional effects obviously appear only when the distribution of the breaking strengths is inhomogeneous. In addition, the stiffness ratio, defined as the ratio of the coil spring strength, Kc, to the leaf spring strength, Kl, is also a factor in controlling slip complexity.

  19. [Evaporating Droplet and Imaging Slip Flows

    NASA Technical Reports Server (NTRS)

    Larson, R. G.

    2002-01-01

    In this report, we summarize work on Evaporating Droplet and Imaging Slip Flows. The work was primarily performed by post-doc Hue Hu, and partially by grad students Lei Li and Danish Chopra. The work includes studies on droplet evaporation and its effects on temperature and velocity fields in an evaporating droplet, new 3-D microscopic particle image velocimetry and direct visualization on wall slip in a surfactant solution. With the exception of the slip measurements, these projects were those proposed in the grant application. Instead of slip flow, the original grant proposed imaging electro-osmotic flows. However, shortly after the grant was issued, the PI became aware of work on electro-osmotic flows by the group of Saville in Princeton that was similar to that proposed, and we therefore elected to carry out work on imaging slip flows rather than electro-osmotic flows.

  20. The role of water in slip casting

    NASA Technical Reports Server (NTRS)

    Mccauley, R. A.; Phelps, G. W.

    1984-01-01

    Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface.

  1. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure.

    PubMed

    Milliner, C W D; Sammis, C; Allam, A A; Dolan, J F; Hollingsworth, J; Leprince, S; Ayoub, F

    2016-01-01

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies. PMID:27256901

  2. Overview of cenozoic strike-slip displacement of the caribbean plate

    SciTech Connect

    Mann, P.

    1985-01-01

    Geologic and tectonic studies in the Caribbean region have traditionally focused on Cretaceous and Paleogene arc rocks which, for the most part, record a long period (approx. = 100 Ma) of plate convergence. Since the recognition of the plate structure of the Caribbean by Molnar and Sykes in 1969, there has been steadily increasing interest in mapping widespread ares of Neogene sedimentary and volcanic rocks that generally record a long period (65.-40 Ma) of eastward displacement of the Caribbean plate relative to the Americas. The purpose of this talk is to review different aspects of present knowledge on this strike-slip displacement, namely: 1) location of major strike-slip faults within the northern and southern plate boundary zones; 2) sense, offset, rate of slip of major strike-slip faults; 3) secondary deformational features related to strike-slip displacements; 4) intraplate deformational features related to interplate strike-slip movements; 5) relation of seismicity to major strike-slip faults; and 6) constraints imposed by strike-slip fault systems on plate motion models. Based on these observations, several critical problems which future studies might help resolve are pointed out.

  3. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure

    PubMed Central

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

    2016-01-01

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies. PMID:27256901

  4. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies.

  5. Variation in aseismic slip and fault normal strain along the creeping section of the San Andreas fault from GPS, InSAR and trilateration data

    NASA Astrophysics Data System (ADS)

    Rolandone, F.; Johanson, I.; Bürgmann, R.; Agnew, D.

    2004-12-01

    In central California most of the relative motion between the Pacific and North American plates is accommodated by strike slip along the San Andreas fault system. However, a small amount of convergence is accommodated by compressional structures in the California Coast Ranges on both sides of the fault. Recent examples of such activity are the Coalinga and the 2003 San Simeon earthquakes. Along the central San Andreas fault (CSAF), from San Juan Bautista to Parkfield, almost all the slip along the CSAF in the brittle upper crust is accommodated aseismically. We use GPS, InSAR and trilateration data to resolve both the distribution of aseismic slip along the CSAF, and the deformation across adjacent, secondary fault structures. In 2003 and 2004, we conducted several GPS surveys along the CSAF. We resurveyed 15 stations of the San Benito triangulation and trilateration network, which extends 40 km to the northeast of the creeping segment. We combine these measurements with old EDM measurements and data from a GPS campaign in 1998. We also occupied 13 sites along the creeping segment, for which previous data exist in the SCEC archive. These dense GPS measurements, along with data from permanent GPS stations in the area, allow us to constrain the regional strain distribution and contributions from adjacent faults. With the addition of InSAR data, we can also better resolve active strain accumulation and aseismic slip along the CSAF. We use a stack of about 10 interferograms from ERS-1 and ERS-2 satellites spanning 8 years. InSAR is well suited to monitoring details of the shallow slip along the CSAF and, in concert with the broadly spaced GPS velocities, to resolving the distribution of deformation along and across the plate boundary. The results are the basis for determining the kinematics of spatially variable fault slip on the CSAF, and help to better constrain the fault's constitutive properties, and fault interaction processes.

  6. Precursory slow crustal deformation before short-term slow slip event in January 2006, recorded at Shingu borehole station southern Kii Peninsula

    NASA Astrophysics Data System (ADS)

    Fukuda, M.; Sagiya, T.

    2007-12-01

    In January 2006, a deep low frequency tremor activity and an associated short-term slow slip event occurred in the eastern Kii Peninsula and this coupled activity migrated to the northeast at a rate of 10km/day. We are monitoring crustal deformation at Shingu borehole station in the southeastern Kii peninsula. The Shingu borehole site is located about 100km landward from the Nankai Trough axis, and close to the epicenter of the 1944 Tonankai Earthquake. The borehole is 500 m deep and is equipped with an integrated multi-component borehole monitoring system developed by Ishii et al. (2002), consisting of 6 strain sensors (4 in horizontal, 2 in vertical), 2 pendulum tilt sensors, a magnetic direction finder, and a quartz thermometer. Each signal is originally recorded with a sampling frequency of 50 Hz. We decimated the original data into hourly data, which we decomposed into tidal response, barometric response, smoothed trend and random noise component by applying BAYTAP-G software [Tamura et al., 1991]. In the trend component from November 2005 to March 2006, we did not found deformation signal at the time of the Jan. 2006 tremor event. However, we found three significant slow strain changes from the processed records. Two of them coincide with the occurrence of the tremor activities in the southern Kii Peninsula, and are characterized by N-S contraction (0.019-0.031 ppm) and E-W extension (0.025-0.038 ppm). These are the first evidence of the short-term slow slip event in this area. The third change is characterized by NW-SE extension (0.026 ppm), N-S contraction (0.012 ppm), E-W extension (0.022 ppm), and southwestward tilting (0.23 micro rad). It occurred from December 29, 2005 to January 2, 2006, just before the tremor and slip event in January 2006, but was not accompanied by any tremor activity. We conducted a series of inversion analysis to infer the source of this possible slow slip event. We assumed that the slow slip event was caused by a reverse fault

  7. Introduction to special section on phenomenology, underlying processes, and hazard implications of aseismic slip and nonvolcanic tremor

    USGS Publications Warehouse

    Gomberg, Joan

    2010-01-01

    This paper introduces the special section on the "phenomenology, underlying processes, and hazard implications of aseismic slip and nonvolcanic tremor" by highlighting key results of the studies published in it. Many of the results indicate that seismic and aseismic manifestations of slow slip reflect transient shear displacements on the plate interface, with the outstanding exception of northern Cascadia where tremor sources have been located on and above the plate interface (differing models of the plate interface there also need to be reconciled). Slow slip phenomena appear to result from propagating deformation that may develop with persistent gaps and segment boundaries. Results add to evidence that when tectonic deformation is relaxed via slow slip, most relaxation occurs aseismically but with seismic signals providing higher-resolution proxies for the aseismic slip. Instead of two distinct slip modes as suggested previously, lines between "fast" and "slow" slip more appropriately may be described as blurry zones. Results reported also show that slow slip sources do not coincide with a specific temperature or metamorphic reaction. Their associations with zones of high conductivity and low shear to compressional wave velocity ratios corroborate source models involving pore fluid pressure buildup and release. These models and spatial anticorrelations between earthquake and tremor activity also corroborate a linkage between slow slip and frictional properties transitional between steady state and stick-slip. Finally, this special section highlights the benefits of global and multidisciplinary studies, which demonstrate that slow phenomena are not confined to beneath the locked zone but exist in many settings.

  8. Slow slip generated by dehydration reaction coupled with slip-induced dilatancy and thermal pressurization

    NASA Astrophysics Data System (ADS)

    Yamashita, Teruo; Schubnel, Alexandre

    2016-05-01

    Sustained slow slip, which is a distinctive feature of slow slip events (SSEs), is investigated theoretically, assuming a fault embedded within a fluid-saturated 1D thermo-poro-elastic medium. The object of study is specifically SSEs occurring at the down-dip edge of seismogenic zone in hot subduction zones, where mineral dehydrations (antigorite, lawsonite, chlorite, and glaucophane) are expected to occur near locations where deep slow slip events are observed. In the modeling, we introduce dehydration reactions, coupled with slip-induced dilatancy and thermal pressurization, and slip evolution is assumed to interact with fluid pressure change through Coulomb's frictional stress. Our calculations show that sustained slow slip events occur when the dehydration reaction is coupled with slip-induced dilatancy. Specifically, slow slip is favored by a low initial stress drop, an initial temperature of the medium close to that of the dehydration reaction equilibrium temperature, a low permeability, and overall negative volume change associated with the reaction (i.e., void space created by the reaction larger than the space occupied by the fluid released). Importantly, if we do not assume slip-induced dilatancy, slip is accelerated with time soon after the slip onset even if the dehydration reaction is assumed. This suggests that slow slip is sustained for a long time at hot subduction zones because dehydration reaction is coupled with slip-induced dilatancy. Such slip-induced dilatancy may occur at the down-dip edge of seismogenic zone at hot subduction zones because of repetitive occurrence of dehydration reaction there.

  9. Quantification of Both Normal and Right-Lateral Late Quaternary Activity Along the Kongur Shan Extensional System, Chinese Pamir

    NASA Astrophysics Data System (ADS)

    Chevalier, M. L.; Pan, J.; Liu, D.; Wang, M.; Lu, H.; Li, H.

    2014-12-01

    The Pamir Mountains, located at the western end of the Indo-Asian collision zone, are one of the most tectonically active regions in central Asia. The Kongur Shan extensional system (KES), located in the Chinese Pamir, accommodates EW extension due to the India/Asia collision and has been the focus on numerous Cenozoic studies, whereas there are very few late Quaternary studies. The KES is mostly normal, except towards its NW end, where it becomes right-lateral strike-slip, along the Muji segment. From Muji to Tashkorgan, we investigated 6 sites, where active normal and/or strike-slip faults cut and offset abandoned river channels or alluvial fans and terraces, which allows us to quantify both the normal and strike-slip motions at different locations along the KES. Our preliminary results yield vertical and right-lateral rates of ~1.8 and >3.2 mm/yr along the northern KES (Muji to Bulunkou) during the Holocene, and of ~1.9-2.7 and ~1 mm/yr along the southern KES (near Taheman) since ~30 ka. These preliminary rates, consistent with GPS data and Cenozoic rates, imply that the EW extension rate due to the northward indentation of the Pamir salient as well as due to the clockwise rotation of the rigid Tarim basin, is partly accommodated by the Muji-Tashkorgan pull-apart basin, and is faster in the north than in the south (from ~5 to ~2 mm/yr).

  10. Constraints and inferences of conditions of seismic slip from analyses of exhumed faults

    NASA Astrophysics Data System (ADS)

    Evans, J. P.

    2008-12-01

    The study of exhumed faults, where constrained by geochemical or geochronologic evidence for depth of deformation, has provided abundant insights into the processes by which the upper crust accommodates strain. What remains elusive in these studies are: a] what evidence do we have for diagnosing [paleo] seismic slip, b ] how do we extrapolate the textures and composition of formerly active faults to constraining the conditions at depth, c] determining the conditions that promote seismic vs. aseismic slip, and d] to what degree do interseismic [healing] and post-slip processes exhumation affect what we see at the surface. Field evidence for the conditions that promote or are of diagnostic seismic vs. aseismic slip, is elusive, as there are few ways to determine seismic rates of slip in faults other than the presence of pseudotachylytes. Recent work on these rocks in a variety of settings and the increase in recognition of the presence of fault- related melts document the relationships between pseudotachylytes and cataclastically deformed rocks in what is thought to be the frictional regime, or with ductily deformed rocks at the base of a fault. Conditions that appear to promote seismic slip are alteration of granitic host rock to lower melting temperature phases and the presence of geometric complexities that may act as stress risers in the faults. Drilling into portions of faults where earthquakes occur at the top of the seismogenic zone have sampled fault-related rocks that have striking similarities to exhumed faults, exhibiting narrow slip surfaces, foliated cataclasites, injected gouge textures, polished slip surfaces, and thermally altered rocks along slip surfaces. We review the recent work from a wide range of studies to suggest that relatively small changes in conditions may initiate seismic slip, and suggest further avenues of investigation.

  11. Using a hybrid Monte Carlo/Genetic Algorithm Slip Estimator to produce high resolution models of paleoearthquakes from geodetic data

    NASA Astrophysics Data System (ADS)

    Lindsay, A.; McCloskey, J.; Nalbant, S. S.; Simao, N.; Murphy, S.; NicBhloscaidh, M.; Steacy, S.

    2013-12-01

    Identifying fault sections where slip deficits have accumulated may provide a means for understanding sequences of large megathrust earthquakes. Stress accumulated during the interseismic period on locked sections of an active fault is stored as potential slip. Where this potential slip remains unreleased during earthquakes, a slip deficit can be said to have accrued. Analysis of the spatial distribution of slip during antecedent events along the fault will show where the locked plate has spent its stored slip and indicate where the potential for large events remains. The location of recent earthquakes and their distribution of slip can be estimated instrumentally. To develop the idea of long-term slip-deficit modelling it is necessary to constrain the size and distribution of slip for pre-instrumental events dating back hundreds of years covering more than one ';seismic cycle'. This requires the exploitation of proxy sources of data. Coral microatolls, growing in the intertidal zone of the outer island arc of the Sunda trench, present the possibility of producing high resolution reconstructions of slip for a number of pre-instrumental earthquakes. Their growth is influenced by tectonic flexing of the continental plate beneath them allows them to act as long term geodetic recorders. However, the sparse distribution of data available using coral geodesy results in a under determined problem with non-unique solutions. Instead of producing one definite model satisfying the observed corals displacements, a Monte Carlo Slip Estimator based on a Genetic Algorithm (MCSE-GA) accelerating the rate of convergence is used to identify a suite of models consistent with the data. Successive iterations of the MCSE-GA sample different displacements at each coral location, from within the spread of associated uncertainties, producing a catalog of models from the full range of possibilities. The suite of best slip distributions are weighted according to their fitness and stacked to

  12. Laboratory Observations of the Spectrum of Fault Slip: Implications for Slow Earthquakes

    NASA Astrophysics Data System (ADS)

    Leeman, John; Saffer, Demian; Scuderi, Marco; Marone, Chris

    2016-04-01

    Fault zone failure spans a wide range of slip modes, including normal earthquakes, low-frequency earthquakes, episodic tremor and slip, non-volcanic tremor, slow slip events, and steady aseismic creep. Despite widespread observations in a range of tectonic and geologic environments, the physics underlying these events remain poorly understood. Here we present a systematic laboratory study of slow slip and build a mechanical explanation for the spectrum of fault slip modes. We show that complex behaviors can arise from relatively simple models using traditional rate-and-state friction (RSF) concepts. We sheared quartz gouge at constant velocity in a double-direct shear configuration. We controlled the effective stiffness of the system by changing the normal stress and changing the material of the loading blocks from steel to acrylic. There is a critical stiffness value (kc) that represents a bifurcation point separating stable and unstable systems. For systems in which k < kc, the rate at which the fault weakens is greater than that at which the surrounding elastic material can release energy into the system, therefore generating a force imbalance and acceleration to fully dynamic and unstable stick-slip. For systems in which k > kc, the surrounding media unloads energy faster than the fault can weaken and therefore the system is stable. For experiments that exhibited stable behavior, we used velocity step tests and RSF modeling tools to independently determine constitutive frictional parameters and calculate the system critical stiffness. For experiments that exhibited unstable behavior we measured the stiffness of the layer directly from displacement and load measurements during individual stick-slip events, and compared it to the calculated value of kc. We find that the predicted stability boundary (defined by k/kc = 1) delineates stable and unstable slip behavior in our experiments, but rather than a strict bifurcation, slow slip and quasi-dynamic failure occur

  13. Manually controlled neutron-activation system

    NASA Astrophysics Data System (ADS)

    Johns, R. A.; Carothers, G. A.

    1982-01-01

    A manually controlled neutron activation system, the Manual Reactor Activation System, was designed and built and has been operating at one of the Savannah River Plant's production reactors. With this system, samples can be irradiated for up to 24 hours and pneumatically transferred to a shielded repository for decay until their activity is low enough for them to be handled at a radiobench. The Manual Reactor Activation System was built to provide neutron activation of solid waste forms for the Alternative Waste Forms Leach Testing Program. Neutron activation of the bulk sample prior to leaching permits sensitive multielement radiometric analyses of the leachates.

  14. Wave activated power generation system

    SciTech Connect

    Ono, Y.

    1983-08-09

    A wave activated power generation system of the float type is disclosed, comprising at least one piston-cylinder device having an anchored cylinder and a piston slidable in the cylinder and cooperating with the cylinder to form a pumping chamber above the piston and a low pressure chamber below the piston. The cylinder has an intake port and an exhaust port both formed at an upper port thereof to communicate with the pumping chamber and each provided with a check valve. A float is connected through a cable to the piston of the piston- cylinder device. A pair of fluid storages are connected to the intake port and the exhaust port of the pumping chamber, respectively. A waterwheel generator is driven by the fluid flowing from one of the fluid storages to another. A pressure regulating device is connected to the low pressure chamber so as to maintain the low pressure chamber at a pressure lower than the pressure in the pumping chamber, the difference in pressure ceaselessly applying a downward force on the piston to keep the cable in a tensed condition.

  15. Dynamic Mechanochemistry of Seismic Slip -Nano Spherules Lubrication

    NASA Astrophysics Data System (ADS)

    Tanaka, H.; Chen, W.; Chen, Y.; Song, Y.; Ma, K.

    2007-12-01

    The Chelungpu fault, which was activated during 1999Chi-Chi Earthquake, had been drilled (Hole A, B and C) to recover the earthquake slip zone materials. We present here the results of nano-scale observations for identified slip zone materials (Ma, Tanaka et al., 2006) by using HR-TEM and TXM technique. Minimum size of grains observed under HR-TEM is 3 nm. The grain size distribution for grains larger than 100 nm in diameter follows the fractal law and grain shape is highly irregular. Grains smaller than100 nm show some specific characteristics, that is, smaller the grains, more the spherical shapes and more equi-granular. Thus, the grains smaller than 100 nm are no longer described by fractal distribution model. By SAD and EDX analysis under HR-TEM, the nano spherules are mainly composed of crystallized quartz associated with minor amounts of carbonates and amorphous materials. Results of observations lead following three conclusions, (1) nano spherules are not generated just by fracturing based on their shapes and grain size distributions. (2) nano spherules would compose viscous materials enveloping larger fractured grains from SEM observations. (3) Mica clay minerals and feldspars are disappeared in ultra-fine grained layer. This implies that chemical process of dissolution - elements dissipation - SiO2 precipitation occurred associated with mechanical fracturing. Therefore nano spherules would be generated through mechano-chemical process during co-seismic slip. Dynamic shear strength drop by rapid slip experimentsare and formation of gelled materials are recently reported. Large differences of ultra-fine products between previous reports and our observations are existence of nano spherules and their crystallinity. If the nano- spherules are generated during seismic slip, dynamic weakening would be expected because mode of friction turns into rolling friction by huge amounts of equigranular and spherical grains. This may be alternative explanations for dynamic

  16. Fusion by earthquake fault friction: Stick or slip?

    NASA Astrophysics Data System (ADS)

    Fialko, Yuri; Khazan, Yakov

    2005-12-01

    Field observations of pseudotachylites and experimental studies of high-speed friction indicate that melting on a slipping interface may significantly affect the magnitude of shear stresses resisting slip. We investigate the effects of rock melting on the dynamic friction using theoretical models of shear heating that couple heat transfer, thermodynamics of phase transitions, and fluid mechanics. Results of laboratory experiments conducted at high (order of m/s) slip velocities but low (order of MPa) normal stresses suggest that the onset of frictional melting may give rise to substantial increases in the effective fault strength, presumably due to viscous effects. However, extrapolation of the modeling results to in situ conditions suggests that the efficiency of viscous braking is significantly reduced under high normal and shear stresses. When transient increases in the dynamic fault strength due to fusion are not sufficient to inhibit slip, decreases in the effective melt viscosity due to shear heating and melting of clasts drastically decrease the dynamic friction, resulting in a nearly complete stress drop ("thermal runaway"). The amount of energy dissipation associated with the formation of pseudotachylites is governed by the temperature dependence of melt viscosity and the average clast size in the fault gouge prior to melting. Clasts from a coarse-grained gouge have lower chances of survival in a pseudotachylite due to a higher likelihood of nonequilibrium overheating. The maximum temperature and energy dissipation attainable on the fault surface are ultimately limited by either the rock solidus (via viscous braking, and slip arrest) or liquidus (via thermal runaway and vanishing resistance to sliding). Our modeling results indicate that the thermally activated fault strengthening and rupture arrest are unlikely to occur in most mafic protoliths but might be relevant for quartz-rich rocks, especially at shallow (<5-7 km) depths where the driving shear

  17. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

    Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific-North American transform plate motion. The Walker Lane is composed of discontinuous sets of right-slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right-lateral shear is locally accommodated by rotation of crustal blocks bounded by steep-dipping east striking left-slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right-lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike-slip faults in the central Walker Lane is abrupt and reflects transfer of strike-slip to dip-slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long-lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic-brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker

  18. Physicochemical analysis of slip flow phenomena in liquids under nanoscale confinement.

    PubMed

    Babu, Jeetu S; Uday, Swathi; Sekhar, Suneeth; Sathian, Sarith P

    2015-10-01

    Eyring theory employs the statistical mechanical theory of absolute reaction rates to analyse the transport mechanisms in fluids. A physicochemical methodology combining molecular dynamics (MD) and Eyring theory of reaction rates is proposed for investigating the liquid slip on a solid wall in the nanoscale domain. The method involves the determination of activation energy required for the flow process directly from the MD trajectory information and then calculate the important transport properties of the confined fluid from the activation energy. In order to demonstrate the universal applicability of the proposed methodology in nanofluidics, the slip flow behavior of argon, water and ionic liquid confined in various nanostructures has been investigated. The slip length is found to be size dependent in all the cases. The novelty of this method is that the variations in slip length are explained on the basis of molecular interactions and the subsequent changes in the activation energy. PMID:26490250

  19. Quantum Phase Slips in Topological Josephson Junction Rings

    NASA Astrophysics Data System (ADS)

    Rodriguez Mota, Rosa; Vishveshwara, Smitha; Pereg-Barnea, Tami

    We study quantum phase slip processes (QPS) in a ring of N topological superconducting islands joined by Josephson junctions and threaded by magnetic flux. In this array, neighboring islands interact through the usual charge 2e Josephson tunneling and the Majorana assisted charge e tunneling. When the charging energy associated with the island's capacitance is zero, the energy vs. flux relation of the system is characterized by parabolas centered around even or odd multiples of the superconducting flux quantum, depending on the parity of the system. For small but non-zero charging energy, quantum fluctuations can lead to tunneling between these classical states. In this work, we calculate the amplitude of these tunneling processes, commonly known as quantum phase slips. We also add gate voltages to our system and study how the amplitude of QPS in these topological Josephson array is modified by Aharanov-Casher interference effects.

  20. Maximum slip in earthquake fault zones, apparent stress, and stick-slip friction

    USGS Publications Warehouse

    McGarr, A.; Fletcher, Joe B.

    2003-01-01

    The maximum slip, observed or inferred, for a small patch within the larger fault zone of an earthquake is a remarkably well-constrained function of the seismic moment. A large set of maximum slips, mostly derived from slip models of major earthquakes, indicate that this parameter increases according to the cube root of the seismic moment. Consistent with this finding, neither the average slip rate for the patches of maximum slip nor the apparent stresses of earthquakes show any systematic dependence on seismic moment. Maximum average slip rates are several meters per second independent of moment and, for earthquakes in continental crustal settings, the apparent stress is limited to about 10 MPa. Results from stick-slip friction experiments in the laboratory, combined with information about the state of stress in the crust, can be used to predict, quite closely, the maximum slips and maximum average slip rates within the fault zones of major earthquakes as well as their apparent stresses. These findings suggest that stick-slip friction events observed in the laboratory and earthquakes in continental settings, even with large magnitudes, have similar rupture mechanisms.

  1. Late Quaternary slip on the Santa Cruz Island fault, California

    USGS Publications Warehouse

    Pinter, N.; Lueddecke, S.B.; Keller, E.A.; Simmons, K.R.

    1998-01-01

    The style, timing, and pattern of slip on the Santa Cruz Island fault were investigated by trenching the fault and by analysis of offset late Quaternary landforms. A trench excavated across the fault at Christi Beach, on the western coast of the island, exposed deformation of latest Pleistocene to Holocene sediments and pre-Quaternary rocks, recording repeated large-magnitude rupture events. The most recent earthquake at this site occurred ca. 5 ka. Coastal terraces preserved on western Santa Cruz Island have been dated using the uranium-series technique and by extrapolation using terrace elevations and the eustatic record. Offset of terraces and other landforms indicates that the Santa Cruz Island fault is predominantly left lateral, having a horizontal slip rate of not more than 1.1 mm/yr and probably about 0.8 mm/yr. The fault also has a smaller reverse component, slipping at a rate of between 0.1 and 0.2 mm/yr. Combined with measurements of slip per event, this information suggests a long-term average recurrence interval of at least 2.7 k.y. and probably 4-5 k.y., and average earthquake magnitudes of Mw 7.2-7.5. Sense of slip, recurrence interval, and earthquake magnitudes calculated here for the Santa Cruz Island fault are very similar to recent results for other faults along the southern margin of the western Transverse Range, including the Malibu Coast fault, the Santa Monica fault, the Hollywood fault, and the Raymond fault, supporting the contention that these faults constitute a continuous and linked fault system, which is characterized by large but relatively infrequent earthquakes.

  2. Slip and Dilation Tendency Analysis of the Patua Geothermal Area

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = τ / σn (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (σ1-σn) / (σ1-σ3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes

  3. Imaging of early acceleration phase of the 2013-2014 Boso slow slip event

    NASA Astrophysics Data System (ADS)

    Fukuda, J.; Kato, A.; Obara, K.; Miura, S.; Kato, T.

    2014-12-01

    Based on GPS and seismic data, we examine the spatiotemporal evolution of a slow slip event (SSE) and associated seismic activity that occurred off the Boso peninsula, central Japan, from December 2013 to January 2014. We use GPS data from 71 stations of the GEONET and 6 stations operated by Earthquake Research Institute of the University of Tokyo and Tohoku University around the Boso peninsula. We apply a modified version of the Network Inversion Filter to the GPS time series at the 77 stations to estimate the spatiotemporal evolution of daily cumulative slip and slip rate on the subducting Philippine Sea plate. In addition, we create an improved earthquake catalog by applying a matched filter technique to continuous seismograms and examine the spatiotemporal relations between slow slip and seismicity. We find that the SSE started in early December 2013. The spatiotemporal evolution of slow slip and seismicity is divided into two distinct phases, an earlier slow phase from early to 30 December 2013 (Phase I) and a subsequent faster phase from 30 December 2013 to 9 January 2014 (Phase II). During Phase I, slip accelerated slowly up to a maximum rate of 1.6 m/yr with potentially accelerating along-strike propagation at speeds on the order of 1 km/day or less and no accompanying seismicity. On the other hand, during Phase II, slip accelerated rapidly up to a maximum rate of 4.5 m/yr and then rapidly decelerated. The slip front propagated along strike at a constant speed of ~10 km/day. During the Phase II, slow slip was accompanied by seismic swarm activity that was highly correlated in space and time with slip rate, suggesting that the swarm activity was triggered by stress loading due to slow slip. Early slow acceleration of slip has not been identified in the past Boso SSEs in 1996, 2002, 2007, and 2011. It is not clear at this point whether the past Boso SSEs started with slow acceleration similarly to the 2013-2014 SSE. The transition from the slow to the

  4. Multiparameter investigation of gravitational slip

    SciTech Connect

    Daniel, Scott F.; Caldwell, Robert R.; Cooray, Asantha; Serra, Paolo; Melchiorri, Alessandro

    2009-07-15

    A detailed analysis of gravitational slip, a new post-general relativity cosmological parameter characterizing the degree of departure of the laws of gravitation from general relativity on cosmological scales, is presented. This phenomenological approach assumes that cosmic acceleration is due to new gravitational effects; the amount of spacetime curvature produced per unit mass is changed in such a way that a universe containing only matter and radiation begins to accelerate as if under the influence of a cosmological constant. Changes in the law of gravitation are further manifest in the behavior of the inhomogeneous gravitational field, as reflected in the cosmic microwave background, weak lensing, and evolution of large-scale structure. The new parameter {pi}{sub 0} is naively expected to be of order unity. However, a multiparameter analysis, allowing for variation of all of the standard cosmological parameters, finds that {pi}{sub 0}=0.09{sub -0.59}{sup +0.74}(2{sigma}), where {pi}{sub 0}=0 corresponds to a cosmological constant plus cold dark matter universe under general relativity. Future probes of the cosmic microwave background (Planck) and large-scale structure (Euclid) may improve the limits by a factor of 4.

  5. Dual Megathrust Slip Behaviors of the 2014 Iquique Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Meng, L.; Huang, H.; Burgmann, R.; Ampuero, J. P.; Strader, A. E.

    2014-12-01

    The transition between seismic rupture and aseismic creep is of central interest to better understand the mechanics of subduction processes. A M 8.2 earthquake occurred on April 1st, 2014 in the Iquique seismic gap of Northern Chile. This event was preceded by a 2-week-long foreshock sequence including a M 6.7 earthquake. Repeating earthquakes are found among the foreshock sequence that migrated towards the mainshock area, suggesting a large scale slow-slip event on the megathrust preceding the mainshock. The variations of the recurrence time of repeating earthquakes highlights the diverse seismic and aseismic slip behaviors on different megathrust segments. The repeaters that were active only before the mainshock recurred more often and were distributed in areas of substantial coseismic slip, while other repeaters occurred both before and after the mainshock in the area complementary to the mainshock rupture. The spatial and temporal distribution of the repeating earthquakes illustrate the essential role of propagating aseismic slip in leading up to the mainshock and aftershock activities. Various finite fault models indicate that the coseismic slip generally occurred down-dip from the foreshock activity and the mainshock hypocenter. Source imaging by teleseismic back-projection indicates an initial down-dip propagation stage followed by a rupture-expansion stage. In the first stage, the finite fault models show slow initiation with low amplitude moment rate at low frequency (< 0.1 Hz), while back-projection shows a steady initiation at high frequency (> 0.5 Hz). This indicates frequency-dependent manifestations of seismic radiation in the low-stress foreshock region. In the second stage, the high-frequency rupture remains within an area of low gravity anomaly, suggesting possible upper-crustal structures that promote high-frequency generation. Back-projection also shows an episode of reverse rupture propagation which suggests a delayed failure of asperities in

  6. Is slow slip in Cascadia tidally modulated?

    NASA Astrophysics Data System (ADS)

    Hawthorne, J. C.; Rubin, A. M.

    2009-12-01

    Several studies have shown that the seismic tremor in episodic tremor and slip is tidally modulated, suggesting a strong sensitivity to the rather small tidal stresses. We address whether the slip is also tidally modulated by examining data from six borehole strainmeters in northwest Washington and southern Vancouver Island. We use the processed data provided by Plate Boundary Observatory (PBO), which is resampled to 5-minute intervals. However, we recompute empirical corrections for tides, a long-term linear trend, and barometric pressure in the 50 days surrounding each slow slip event. We then fit sinusoids at the tidal periods to the processed data as proxies for the tidally modulated component of slip, along with a linear trend as a proxy for the net strain in the slow slip. The data are too noisy to allow detection any tidal modulation using only a single event and station. We therefore simultaneously fit data from multiple stations and from three slow slip events since 2007. This assumes that the phase of the tides at the slipping regions detected by all stations is the same and that the phase of the fault response to the tidal stress is constant. Combining the stations and events both reduces the noise at the tidal periods and creates a longer time series, which allows us to separate energy at the different tidal frequencies. We find significant tidal signals at the 12.4 and 25.8-hour periods which differ from zero at the 1.5 to 2-sigma level. Errors are estimated by bootstrapping the slow slip strain and by considering the tidal signal at times before the slow slip event. The 12.4 and 25.8-hour sinusoids have amplitudes of 23 (10-40 at 2-sigma) and 15 (0-30 at 2-sigma) percent of the maximum amplitude that does not allow the slow slip strain signal to change sign, where the mean strain rate is estimated from the linear trends fit to the slow slip data. In terms of slip rate, the sinusoids at each period could then modulate the slip rate 23 and 15 percent

  7. Variability of fault slip behavior along the San Andreas Fault in the San Juan Bautista Region

    NASA Astrophysics Data System (ADS)

    Taira, Taka'aki; Bürgmann, Roland; Nadeau, Robert M.; Dreger, Douglas S.

    2014-12-01

    An improved understanding of the time history of fault slip at depth is an essential step toward understanding the underlying mechanics of the faulting process. Using a waveform cross-correlation approach, we document spatially and temporally varying fault slip along the northernmost creeping section of the San Andreas Fault near San Juan Bautista (SJB), California, by systematically examining spatiotemporal behaviors of characteristically repeating earthquakes (CREs). The spatial distribution of pre-1998 SJB earthquake (1984-1998) fault slip rate inferred from the CREs reveals a ~15 km long low creep or partially locked section located near the 1998 Mw 5.1 SJB earthquake rupture. A finite-fault slip inversion reveals that the rupture of the 1998 SJB earthquake is characterized by the failure of a compact ~4 km2 asperity with a maximum slip of about 90 cm and corresponding peak stress drop of up to 50 MPa, whereas the mean stress drop is about 15 MPa. Following the 1998 earthquake, the CRE activity was significantly increased in a 5-10 km deep zone extending 2-7 km northwest of the main shock, which indicates triggering of substantial aseismic slip. The postseismic slip inferred from the CRE activity primarily propagated to the northwest and released a maximum slip of 9 cm. In this 5-10 km depth range, the estimated postseismic moment release is 8.6 × 1016 N m, which is equivalent to Mw 5.22. The aseismic slip distribution following the 1998 earthquake is not consistent with coseismic stress-driven afterslip but represents a triggered, long-lasting slow earthquake.

  8. A flexible active and reactive power control strategy for a variable speed constant frequency generating system

    SciTech Connect

    Tang, Y.; Xu, L.

    1995-07-01

    Variable-speed constant-frequency generating systems are used in wind power, hydro power, aerospace, and naval power generations to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising of doubly excited induction machine or doubly excited brushless reluctance machine and PWM converters with a dc link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network has also been minimized. In this manner, the system can function as both a high-efficient power generator and a flexible reactive power compensator.

  9. Jelly Quakes - Characteristics of periodic slip events in an analog model of strike slip seismotectonics using ballistic gelatin.

    NASA Astrophysics Data System (ADS)

    Rudolf, Michael; Rosenau, Matthias; Oncken, Onno

    2016-04-01

    Large lithospheric strike-slip faults, such as the San-Andreas Fault, North-Anatolian Fault, or the Tancheng-Lujiang Faultzone, are major sources of seismic hazard. The interplay of complex 3D-geometry and displacement style along the fault, coupled with a varying rheological layering makes it very difficult to model these faults on all relevant timescales. Here we present a novel experimental approach to model intra- and interplate strike-slip faults using a physical/ analog model. We model earthquakes as a stick-slip process, following a rate-and-state frictional law, with glass beads as granular material within a molded fault zone. Crustal elasticity is introduced by using ballistic gelatin (30 w%, pig skin) as analog material. Furthermore, the low-strength and viscous deep crust below 15 km depth, is modeled using a viscoelastic silicone oil (PDMS-G30M). The layered model crust floats on sugar syrup and is compressed in pure shear vice configuration. We monitor the compressive force along with surface kinematics from optical image correlation. The fault is oriented at 45° to the compression direction imposing ideal strike-slip kinematics onto it. After an initial loading phase the model shows periodic slip events occurring alongside with creep on the fault. Using digital image correlation, surface displacement maps are obtained which are similar to those of natural earthquakes. Coseismic displacement along strike is showing a similar bell-shaped distribution as for natural faults. Furthermore, the recurrence intervals and stress drops are scalable to the natural prototype. The modeling results are combined with numerical rate-and-state models using physical parameters from the experiment. This enables us to explore a wide range of parameters and to draw connections between the parameters that control the behavior of seismic and aseismic fault systems.

  10. What Is an Activity? Appropriating an Activity-Centric System

    NASA Astrophysics Data System (ADS)

    Yarosh, Svetlana; Matthews, Tara; Moran, Thomas P.; Smith, Barton

    Activity-Centric Computing (ACC) systems seek to address the fragmentation of office work across tools and documents by allowing users to organize work around the computational construct of an Activity. Defining and structuring appropriate Activities within a system poses a challenge for users that must be overcome in order to benefit from ACC support. We know little about how knowledge workers appropriate the Activity construct. To address this, we studied users’ appropriation of a production-quality ACC system, Lotus Activities, for everyday work by employees in a large corporation. We contribute to a better understanding of how users articulate their individual and collaborative work in the system by providing empirical evidence of their patterns of appropriation. We conclude by discussing how our findings can inform the design of other ACC systems for the workplace.

  11. Action slips during whole-body vibration.

    PubMed

    Ishimatsu, Kazuma; Meland, Anders; Hansen, Tor Are S; Kåsin, Jan Ivar; Wagstaff, Anthony S

    2016-07-01

    Helicopter aircrew members engage in highly demanding cognitive tasks in an environment subject to whole-body vibration (WBV). Sometimes their actions may not be according to plan (e.g. action slips and lapses). This study used a Sustained Attention to Response Task (SART) to examine whether action slips were more frequent during exposure to WBV. Nineteen participants performed the SART in two blocks. In the WBV block participants were exposed to 17 Hz vertical WBV, which is typical of larger helicopter working environments. In the No-WBV block there was no WBV. There were more responses to the rare no-go digit 3 (i.e. action slips) in the WBV block, and participants responded faster in the WBV block. These results suggest that WBV influences response inhibition, and can induce impulsive responding. WBV may increase the likelihood of action slips, mainly due to failure of response inhibition. PMID:26611989

  12. Slip-mediated dewetting of polymer microdroplets.

    PubMed

    McGraw, Joshua D; Chan, Tak Shing; Maurer, Simon; Salez, Thomas; Benzaquen, Michael; Raphaël, Elie; Brinkmann, Martin; Jacobs, Karin

    2016-02-01

    Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. PMID:26787903

  13. Bone scintigraphy in slipped capital femoral epiphysis

    SciTech Connect

    Gelfand, M.J.; Strife, J.L.; Graham, E.J.; Crawford, A.H.

    1983-12-01

    Tc-/sub 99m/ diphosphonate bone scans were performed on 11 children with slipped capital femoral epiphysis. On pinhole hip images, seven hips in seven patients had increased radionuclide uptake in the physis and adjacent proximal femoral metaphysis where the slip had occurred. Three hips in three patients had decreased radionuclide uptake in the femoral head on the side of the slipped epiphysis, indicating compromise of the femoral head blood supply. Three or more months following internal fixation, three children had scintigraphy that showed loss of the usual focal uptake in the physis and adjacent proximal femoral metaphysis. Bone scintigraphy in pediatric patients with slipped capital femoral epiphysis is valuable in defining the metabolic status of the femoral head. Absence of radiopharmaceutical uptake in the affected femoral head indicates that the femoral head is at risk for development of radiographic changes associated with aseptic necrosis.

  14. Slip boundary conditions over curved surfaces.

    PubMed

    Guo, Lin; Chen, Shiyi; Robbins, Mark O

    2016-01-01

    Molecular dynamics simulations are used to investigate the influence of surface curvature on the slip boundary condition for a simple fluid. The slip length is measured for flows in planar and cylindrical geometries with a range of wall-fluid interactions. As wall curvature increases, the slip length decreases dramatically for closely packed surfaces and increases for sparse ones. The magnitude of the changes depends on the crystallographic orientation and differs for flow along and perpendicular to the direction of curvature. These different patterns of behavior are related to the curvature-induced variation in the ratio of the spacing between fluid atoms to the spacing between minima in the potential from the solid surface. The results are consistent with a microscopic theory for the viscous friction between fluid and wall that expresses the slip length in terms of the lateral response of the fluid to the wall potential and the characteristic decay time of this response. PMID:26871153

  15. Slip boundary conditions over curved surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Lin; Chen, Shiyi; Robbins, Mark O.

    2016-01-01

    Molecular dynamics simulations are used to investigate the influence of surface curvature on the slip boundary condition for a simple fluid. The slip length is measured for flows in planar and cylindrical geometries with a range of wall-fluid interactions. As wall curvature increases, the slip length decreases dramatically for closely packed surfaces and increases for sparse ones. The magnitude of the changes depends on the crystallographic orientation and differs for flow along and perpendicular to the direction of curvature. These different patterns of behavior are related to the curvature-induced variation in the ratio of the spacing between fluid atoms to the spacing between minima in the potential from the solid surface. The results are consistent with a microscopic theory for the viscous friction between fluid and wall that expresses the slip length in terms of the lateral response of the fluid to the wall potential and the characteristic decay time of this response.

  16. Case history of a slip-type rockburst

    NASA Astrophysics Data System (ADS)

    Williams, T. J.; Wideman, C. J.; Scott, D. F.

    1992-09-01

    First-motion analyses of digital seismic records and an assessment of damage provided conclusive evidence that a fault-slip source mechanism was responsible for a Richter magnitude 2 that occurred at the Lucky Friday Mine on April 13, 1990. This event was the first time that movement along an argillite bed had been observed after the macroseismic monitoring system had been installed. The physical evidence of a shear-slip type failure established confidence in using double-couple, first-motion analyses for the macroseismic system. The U.S. Bureau of Mines is conducting this research as part of its mission to enhance safety by reducing rockburst hazards in mines.

  17. Slip Ratio Estimation and Regenerative Brake Control for Decelerating Electric Vehicles without Detection of Vehicle Velocity and Acceleration

    NASA Astrophysics Data System (ADS)

    Suzuki, Toru; Fujimoto, Hiroshi

    In slip ratio control systems, it is necessary to detect the vehicle velocity in order to obtain the slip ratio. However, it is very difficult to measure this velocity directly. We have proposed slip ratio estimation and control methods that do not require the vehicle velocity with acceleration. In this paper, the slip ratio estimation and control methods are proposed without detecting the vehicle velocity and acceleration when it is decelerating. We carried out simulations and experiments by using an electric vehicle to verify the effectiveness of the proposed method.

  18. Dual megathrust slip behaviors of the 2014 Iquique earthquake sequence

    NASA Astrophysics Data System (ADS)

    Meng, Lingsen; Huang, Hui; Bürgmann, Roland; Ampuero, Jean Paul; Strader, Anne

    2015-02-01

    The transition between seismic rupture and aseismic creep is of central interest to better understand the mechanics of subduction processes. A Mw 8.2 earthquake occurred on April 1st, 2014 in the Iquique seismic gap of northern Chile. This event was preceded by a long foreshock sequence including a 2-week-long migration of seismicity initiated by a Mw 6.7 earthquake. Repeating earthquakes were found among the foreshock sequence that migrated towards the mainshock hypocenter, suggesting a large-scale slow-slip event on the megathrust preceding the mainshock. The variations of the recurrence times of the repeating earthquakes highlight the diverse seismic and aseismic slip behaviors on different megathrust segments. The repeaters that were active only before the mainshock recurred more often and were distributed in areas of substantial coseismic slip, while repeaters that occurred both before and after the mainshock were in the area complementary to the mainshock rupture. The spatiotemporal distribution of the repeating earthquakes illustrates the essential role of propagating aseismic slip leading up to the mainshock and illuminates the distribution of postseismic afterslip. Various finite fault models indicate that the largest coseismic slip generally occurred down-dip from the foreshock activity and the mainshock hypocenter. Source imaging by teleseismic back-projection indicates an initial down-dip propagation stage followed by a rupture-expansion stage. In the first stage, the finite fault models show an emergent onset of moment rate at low frequency (< 0.1 Hz), while back-projection shows a steady increase of high frequency power (> 0.5 Hz). This indicates frequency-dependent manifestations of seismic radiation in the low-stress foreshock region. In the second stage, the rupture expands in rich bursts along the rim of a semi-elliptical region with episodes of re-ruptures, suggesting delayed failure of asperities. The high-frequency rupture remains within an

  19. Spatial organization of plastic deformation in single crystals with different structure of slip dislocation

    SciTech Connect

    Kunitsyna, T. S.; Teplyakova, L. A. Koneva, N. A.; Poltaranin, M. A.

    2015-10-27

    It is established that different structure of slip dislocation at the end of the linear hardening stage results in different distribution of dislocation charges in the volume of a single crystal. In the alloy with a near atomic order the slip of single dislocations leads to formation of planar structures—layers with the excess density of dislocations. In the alloy with long-range atomic order the slip of superdislocations brings the formation of the system of parallel rod-like charged dislocation linking.

  20. Detection and Monitoring of Ongoing Aseismic Slip in the Tokai Region, Central Japan

    NASA Astrophysics Data System (ADS)

    Ozawa, Shinzaburo; Murakami, Makoto; Kaidzu, Masaru; Tada, Takashi; Sagiya, Takeshi; Hatanaka, Yuki; Yarai, Hiroshi; Nishimura, Takuya

    2002-11-01

    Analysis of global positioning system data shows that the rate of crustal deformations in the Tokai region of Japan, a seismic gap area, changed over the past 18 months. Kalman filtering analysis shows aseismic slip on the plate boundary in the western Tokai region centered on Lake Hamana, adjacent to the anticipated Tokai earthquake source area. The cumulative moment magnitude reaches 6.7 in June 2002 with a relative slip increase northeast of Lake Haman from January 2002. An existence of aseismic slip in the western Tokai supports the hypothesis of a silent event as the cause of uplifting several days before the 1944 Tonankai earthquake.

  1. Detection and monitoring of ongoing aseismic slip in the Tokai region, central Japan.

    PubMed

    Ozawa, Shinzaburo; Murakami, Makoto; Kaidzu, Masaru; Tada, Takashi; Sagiya, Takeshi; Hatanaka, Yuki; Yarai, Hiroshi; Nishimura, Takuya

    2002-11-01

    Analysis of global positioning system data shows that the rate of crustal deformations in the Tokai region of Japan, a seismic gap area, changed over the past 18 months. Kalman filtering analysis shows aseismic slip on the plate boundary in the western Tokai region centered on Lake Hamana, adjacent to the anticipated Tokai earthquake source area. The cumulative moment magnitude reaches 6.7 in June 2002 with a relative slip increase northeast of Lake Haman from January 2002. An existence of aseismic slip in the western Tokai supports the hypothesis of a silent event as the cause of uplifting several days before the 1944 Tonankai earthquake. PMID:12364622

  2. Late Quaternary Range-Front Fault Scarps in the Western Sierra El Mayor, Baja California, Mexico: A Geomorphologic Expression of Slip Across an Active Low-Angle Normal Fault

    NASA Astrophysics Data System (ADS)

    Spelz, R. M.; Fletcher, J.; Owen, L.

    2006-12-01

    The western margin of the Sierra El Mayor (SEM), in northeastern Baja California, is controlled by an active, top-to-the-west, low-angle normal fault named the Canada David detachment (CDD) that accommodates part of the extensional component of shearing between the Pacific and North American plates. The CDD has a length of 60 km and shows a curvilinear trace with two major antiformal and synformal megamullion pairs. Late Quaternary slip has produced a broad array of Quaternary scarps cutting alluvial fans along nearly the entire length of the CDD. Detailed mapping reveals eight regional strath terraces distinguished by surface weathering characteristics, soil profile development and relative elevation. Relative height between terraces increases in domains where the CDD and basin deposits are being uplifted due to either the basinward migration of faulting (e.g., rolling hinge) or flexural uplift in antiformal megamullion domains. Linear diffusion analysis of 46 synthetic fault scarps, with a calculated angle of repose Θo = 28.75°, reveal fault scarp domains exhibiting both multi-modal and unimodal distribution of diffusion ages (kt). Uni-modal domains are typically younger, but there is no systematic variation in scarp age with distance along the CDD. Scarps yielding negative kt ages (i.e. scarps steeper than Θo) are common in the north, near inferred locations of important historic seismic events. Microseismicity drops off significantly adjacent to these very young scarp arrays, which likely reflects a recent post-seismic stress drop. Domains of high seismic risk are identified by high microseismicity and lack of young scarps. Minimum estimates of the diffusivity constant (k) are calculated by coupling scarp diffusion ages and 10Be surface exposure ages of the faulted deposits. In the southernmost SEM a Q6 terrace with a minimum surface exposure age t = 233±6.6 ky (weighted mean of six rock samples) is cut by scarps with an average kt = 11.25±9.31 m2, which

  3. Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area

    DOE Data Explorer

    Faulds, James E.

    2013-12-31

    Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = τ / σn (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (σ1-σn) / (σ1-σ3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes

  4. Adaptive control of gait stability in reducing slip-related backward loss of balance.

    PubMed

    Bhatt, T; Wening, J D; Pai, Y-C

    2006-03-01

    The properties of adaptation within the locomotor and balance control systems directed towards improving one's recovery strategy for fall prevention are not well understood. The purpose of this study was to examine adaptive control of gait stability to repeated slip exposure leading to a reduction in backward loss of balance (and hence in protective stepping). Fourteen young subjects experienced a block of slips during walking. Pre- and post-slip onset stability for all slip trials was obtained as the shortest distance at touchdown (slipping limb) and lift-off (contralateral limb), respectively, between the measured center of mass (COM) state, that is, position and velocity relative to base of support (BOS) and the mathematically predicted threshold for backward loss of balance. An improvement in pre- and post-slip onset stability correlated with a decrease in the incidence of balance loss from 100% (first slip) to 0% (fifth slip). While improvements in pre-slip stability were affected by a proactive anterior shift in COM position, the significantly greater post-slip onset improvements resulted from reductions in BOS perturbation intensity. Such reactive changes in BOS perturbation intensity resulted from a reduction in the demand on post-slip onset braking impulse, which was nonetheless influenced by the proactive adjustments in posture and gait pattern (e.g., the COM position, step length, flat foot landing and increased knee flexion) prior to slip onset. These findings were indicative of the maturing process of the adaptive control. This was characterized by a shift from a reliance on feedback control for postural correction to being influenced by feedforward control, which improved pre-slip stability and altered perturbation intensity, leading to skateover or walkover (>0.05 m or <0.05 m displacement, respectively) adaptive strategies. Finally, the stability at contralateral limb lift-off was highly predictive of balance loss occurrence and its subsequent rapid

  5. Dynamics of Slip Fronts at Frictional Interfaces: Analysis of Slip Precursors

    NASA Astrophysics Data System (ADS)

    Radiguet, M.; Kammer, D. S.; Molinari, J.

    2012-12-01

    The transition from sticking to sliding of frictional interfaces is a phenomenon of importance for many physical systems in nature as well as in engineering. This transition is marked by the occurrence of local slip events, often called precursors, which appear before the global sliding is observed. Such precursors to global sliding may occur on segments of geophysical faults subject to non uniform shear loading, for example a fault segment located between a locked and steadily slipping region. Sequences of small earthquakes (foreshocks) of identical seismic characteristics have been observed preceding large earthquakes in several regions. The links between the occurrence of these foreshocks and the nucleation process of large earthquakes remains elusive, but has large implications for earthquake prediction and risk assessment. These precursors have been studied experimentally by Rubinstein et al. [2007]. However, the experimental study of interfaces is challenging due to difficulties to access information at the interface. Therefore, numerical simulations are needed in order to give additional information for accurate analysis. First attempts have been undertaken using simple spring-block systems [Maegawa et al. 2010, Tromborg et al. 2011]. In this study however, we use the finite-element method, which allows us to represent accurately the continuum character of the system, and to investigate the onset and evolution of sliding at a frictional interface. The studied setup is similar to the experimental setup used by Ben-David et al. [2010]. It consists of a block of viscoelastic material in contact with a rigid body. A velocity-weakening friction law controls the friction at the interface. Special care is taken to apply appropriate regularization and viscosity in the simulation. We apply a shear load to the block, either on the top surface of the block or on one side. In both cases, the resulting shear tractions at the interface are non-uniform. The stress

  6. From frictional fingers to stick slip bubbles

    NASA Astrophysics Data System (ADS)

    Sandnes, Bjørnar; Jørgen Måløy, Knut; Flekkøy, Eirik; Eriksen, Jon

    2014-05-01

    Gas intrusion into wet porous/deformable/granular media occurs in a wide range of natural and engineered settings. Examples include hydrocarbon recovery, carbon dioxide geo-sequestration, gas venting in sediments and volcanic eruptions. In the case where the intruding gas is able to displace particles and grains, local changes in granular packing fraction govern the evolution of flow paths, resulting in complex pattern formation of the displacement flow. Here we investigate flow patterning as a compressed gas displaces a granular mixture confined in the narrow gap of a Hele-Shaw cell. We find a surprising variety of different pattern formation dynamics, and present a unified phase diagram of the flow morphologies we observe. This talk will focus on one particular transition the system undergoes: from frictional fingers to stick slip bubbles. We show that the frictional fluid flow patterns depend on granular mass loading and system elasticity, analogous to the behaviour of the well-known spring-block sliding friction problem.

  7. Eastern Denali Fault Slip Rate and Paleoseismic History, Kluane Lake Area, Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Seitz, G. J.; Haeussler, P. J.; Crone, A. J.; Lipovsky, P.; Schwartz, D. P.

    2008-12-01

    In 2002, the central part of the dextral-slip Denali fault (DF) system generated a M 7.9 earthquake in central Alaska. This rupture included the section of the Denali fault with the highest measured late Pleistocene slip rate, of 12.1±1.7 mm/yr, and the Totschunda fault, with a slip rate of 6.0±1.2 mm/yr. Immediately east of the Denali-Totschunda fault juncture, the slip rate on the eastern Denali fault (EDF) decreases to 8.4±2.2 mm/yr. We present observations of Holocene fault activity on the Yukon part of the EDF (Shakwak segment), which is located about 280 km southeast of the Denali-Totschunda intersection in the vicinity of Kluane Lake. Aerial reconnaissance in 2007, from the Denali-Totschunda fault juncture to the Kluane Lake region revealed a nearly continuously identifiable fault trace, which is occasionally obscured where it is subparallel to glacial landforms. In addition to geomorphic features associated with strike-slip faults, such as shutter ridges and sag ponds, the fault is commonly expressed by a chain of elongate mounds, likely tectonic pushups, 20-70 m in length, 10-50 m wide, and locally up to 10 m high. These appear to have formed by shortening between en echelon left-stepping fault strands that developed in layered glacial sediments. At one location (61°18'30.12" N, 139°01'02.54"W) we measured on the ground a channel offset of 20-25 m. An aerial view showed that other channels in the vicinity, as well as the margins of two mounds, were offset by similar amounts. These channels likely developed after deglaciation 10-12 ka. Using this age and the offset yields a slip-rate range of 1.7-2.5 mm/yr, a minimum value but one that may be close to the actual rate. However, because of uncertainties in age relations between construction of the uplift mounds and channel incision the offset could be younger and we estimate an upper limit of about 5 mm/yr. Adjacent to and south of the Duke River, an approximately 2-km-long section of the fault is

  8. Stick-slip at soft adhesive interfaces mediated by slow frictional waves.

    PubMed

    Viswanathan, Koushik; Sundaram, Narayan K; Chandrasekar, Srinivasan

    2016-06-28

    Stick-slip is a friction instability that governs diverse phenomena from squealing automobile brakes to earthquakes. At soft adhesive interfaces, this instability has long been attributed to Schallamach waves, which are a type of slow frictional wave. We use a contact configuration capable of isolating single wave events, coupled with high speed in situ imaging, to demonstrate the existence of two new stick-slip modes. It is shown that these modes also correspond to the passage of slow waves-separation pulse and slip pulse-with distinct nucleation and propagation characteristics. The slip pulse, characterized by a sharp stress front, propagates in the same direction as the Schallamach wave. In contrast, the separation pulse, involving local interface detachment and resembling a tensile neck, travels in exactly the opposite direction. A change in the stick-slip mode from the separation to the slip pulse is effected simply by increasing the normal force. Taken together, the three waves constitute all possible stick-slip modes in low-velocity sliding. The detailed observations enable us to present a phase diagram delineating the domains of occurrence of these waves. We suggest a direct analogy between the observed slow frictional waves and well known muscular locomotory waves in soft bodied organisms. Our work answers basic questions about adhesive mechanisms of frictional instabilities in natural and engineered systems, with broader implications for slow surface wave phenomena. PMID:27118236

  9. Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data

    USGS Publications Warehouse

    Johanson, I.A.; Fielding, E.J.; Rolandone, F.; Burgmann, R.

    2006-01-01

    We invert interferometric synthetic aperture radar (InSAR) data jointly with campaign and continuous global positioning system (GPS) data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The InSAR dataset consists of eight interferograms from data collected by the Envisat and Radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period. The two datasets complement each other, with the InSAR providing dense sampling of motion in the range direction of the satellite and the GPS providing more sparse, but three-dimensional measurements of ground motion. The model assumes exponential decay of the postseismic slip with a decay time constant of 0.087 years, determined from time series modeling of continuous GPS and creepmeter data. We find a geodetic moment magnitude of M 6.2 for a 1-day coseismic model and Mw 6.1 for the entire postseismic period. The coseismic rupture occurred mainly in two slip asperities; one near the hypocenter and the other 15-20 km north. Postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two M 5.0 aftershocks. A comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the Parkfield earthquake is as little as 25% of the total. This underlines the importance of aseismic slip in the slip budget for the Parkfield segment.

  10. Quantification of surface charge density and its effect on boundary slip.

    PubMed

    Jing, Dalei; Bhushan, Bharat

    2013-06-11

    Reduction of fluid drag is important in the micro-/nanofluidic systems. Surface charge and boundary slip can affect the fluid drag, and surface charge is also believed to affect boundary slip. The quantification of surface charge and boundary slip at a solid-liquid interface has been widely studied, but there is a lack of understanding of the effect of surface charge on boundary slip. In this paper, the surface charge density of borosilicate glass and octadecyltrichlorosilane (OTS) surfaces immersed in saline solutions with two ionic concentrations and deionized (DI) water with different pH values and electric field values is quantified by fitting experimental atomic force microscopy (AFM) electrostatic force data using a theoretical model relating the surface charge density and electrostatic force. Results show that pH and electric field can affect the surface charge density of glass and OTS surfaces immersed in saline solutions and DI water. The mechanisms of the effect of pH and electric field on the surface charge density are discussed. The slip length of the OTS surface immersed in saline solutions with two ionic concentrations and DI water with different pH values and electric field values is measured, and their effects on the slip length are analyzed from the point of surface charge. Results show that a larger absolute value of surface charge density leads to a smaller slip length for the OTS surface. PMID:23683055

  11. What is hidden in caves? Sheared flowstone as a marker for slip rates

    NASA Astrophysics Data System (ADS)

    Mitrovic, Ivanka; Plan, Lukas; Grasemann, Bernhard; Baron, Ivo

    2015-04-01

    Speleothems are cave deposits, mostly consisting of calcite minerals, and they can be used to investigate tectonic activity of a region, giving that caves naturally preserve past and present conditions often difficult to observe at the surface. Flowstone is a type of speleothem, deposited out of water films along cave walls and is usually characterized by uniform crystal growth characterized by calcite c-axis perpendicular to the cave wall. Scratched flowstone, found in Hirschgruben cave, Austrian Alps, was deformed due to a strike-slip fault movement that occurred between 118 ka and ca. 9 ka, at depths of 190 m below the surface (1890 m above sea level) and low temperatures (0-5 degrees Celsius). After the deformation, a thin layer of younger flowstone coated the scratch, preserving the original slip surface. This allows us to investigate well-preserved natural examples of fault behavior and here we show its complexity. Naturally deformed speleothems have been sheared due to activity of the SEMP (Salzach-Ennstal-Mariazell-Puchberg) fault system and present unique field evidence for active displacement along this fault. The 300 km long SEMP fault accommodated a sinistral displacement of about 60 km related to the Neogene and Quaternary lateral extrusion of the Eastern Alps towards the Pannonian Basin, coeval with north-south shortening between the Adriatic and European plates. Microstructural analysis of sheared flowstone pose evidences for changing fault behavior, including both seismic slip and aseismic creep. To investigate these mechanisms, we implemented series of high-resolution electron beam analytical techniques including scanning electron microscope, cathodoluminescence and electron backscattered diffraction. The most common structural characteristics, such as grain size reduction, mechanical twinning and the presence of crystal-plastic deformation suggest complexity of the fault. In order to better understand this complex fault behavior, we perform

  12. A search in strainmeter data for slow slip associated with triggered and ambient tremor near Parkfield, California

    NASA Astrophysics Data System (ADS)

    Smith, Emily F.; Gomberg, Joan

    2009-12-01

    We test the hypothesis that, as in subduction zones, slow slip facilitates triggered and ambient tremor in the transform boundary setting of California. Our study builds on the study of Peng et al. (2009) of triggered and ambient tremor near Parkfield, California during time intervals surrounding 31, potentially triggering, M ≥ 7.5 teleseismic earthquakes; waves from 10 of these triggered tremor and 29 occurred in periods of ambient tremor activity. We look for transient slow slip during 3-month windows that include 11 of these triggering and nontriggering teleseisms, using continuous strain data recorded on two borehole Gladwin tensor strainmeters (GTSM) located within the distribution of tremor epicenters. We model the GTSM data assuming only tidal and "drift" signals are present and find no detectable slow slip, either ongoing when the teleseismic waves passed or triggered by them. We infer a conservative detection threshold of about 5 nanostrain for abrupt changes and about twice this for slowly evolving signals. This could be lowered slightly by adding analyses of other data types, modeled slow slip signals, and GTSM data calibration. Detection of slow slip also depends on the slipping fault's location and size, which we describe in terms of equivalent earthquake moment magnitude, M. In the best case of the GTSM above a very shallow slipping fault, detectable slip events must exceed M˜2, and if the slow slip is beneath the seismogenic zone (below ˜15 km depth), even M˜5 events are likely to remain hidden.

  13. A search in strainmeter data for slow slip associated with triggered and ambient tremor near Parkfield, California

    USGS Publications Warehouse

    Smith, E.F.; Gomberg, J.

    2009-01-01

    We test the hypothesis that, as in subduction zones, slow slip facilitates triggered and ambient tremor in the transform boundary setting of California. Our study builds on the study of Peng et al. (2009) of triggered and ambient tremor near Parkfield, California during time intervals surrounding 31, potentially triggering, M ≥ 7.5 teleseismic earthquakes; waves from 10 of these triggered tremor and 29 occurred in periods of ambient tremor activity. We look for transient slow slip during 3-month windows that include 11 of these triggering and nontriggering teleseisms, using continuous strain data recorded on two borehole Gladwin tensor strainmeters (GTSM) located within the distribution of tremor epicenters. We model the GTSM data assuming only tidal and “drift” signals are present and find no detectable slow slip, either ongoing when the teleseismic waves passed or triggered by them. We infer a conservative detection threshold of about 5 nanostrain for abrupt changes and about twice this for slowly evolving signals. This could be lowered slightly by adding analyses of other data types, modeled slow slip signals, and GTSM data calibration. Detection of slow slip also depends on the slipping fault's location and size, which we describe in terms of equivalent earthquake moment magnitude, M. In the best case of the GTSM above a very shallow slipping fault, detectable slip events must exceed M~2, and if the slow slip is beneath the seismogenic zone (below ~15 km depth), even M~5 events are likely to remain hidden.

  14. Data base management systems activities

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Data Management System-1100 is designed to operate in conjunction with the UNIVAC 1100 Series Operating System on any 1100 Series computer. DMS-1100 is divided into the following four major software components: (1) Data Definition Languages (DDL); (2) Data Management Routine (DMR); (3) Data Manipulation Languages (DML); and (4) Data Base Utilities (DBU). These software components are described in detail.

  15. Detection and characterization of transient forcing episodes affecting earthquake activity in the Aleutian Arc system

    NASA Astrophysics Data System (ADS)

    Reverso, T.; Marsan, D.; Helmstetter, A.

    2015-02-01

    Crustal, slow deformation transients can be caused by fluid or magmatic intrusions, and by slow slip on faults. They can affect earthquake dynamics, if they occur close to or within seismically active zones. We here further develop, and test, a statistical method for detecting and characterizing seismicity anomalies that is only based on earthquake occurrence times and locations. We make use of this method to analyze the 2004-2013 seismicity at mc = 3.5 in the Aleutian subduction system, to find six statistically significant anomalies, with typical 1 day duration and 30 to 50 km size, that are likely related to slow deformation transients. They tend to be located in zones characterized by intermediate seismic coupling, and to mark the termination of past large to mega-thrust earthquakes. These anomalies account for a non-negligible (9%) part of the total activity, proving that non-stationary aseismic loading plays an important role in the dynamics of crustal deformation.

  16. Orbiter active thermal control system description

    NASA Technical Reports Server (NTRS)

    Laubach, G. E.

    1975-01-01

    A brief description of the Orbiter Active Thermal Control System (ATCS) including (1) major functional requirements of heat load, temperature control and heat sink utilization, (2) the overall system arrangement, and (3) detailed description of the elements of the ATCS.

  17. Coordinated Control of Slip Ratio for Wheeled Mobile Robots Climbing Loose Sloped Terrain

    PubMed Central

    Li, Zhengcai; Wang, Yang

    2014-01-01

    A challenging problem faced by wheeled mobile robots (WMRs) such as planetary rovers traversing loose sloped terrain is the inevitable longitudinal slip suffered by the wheels, which often leads to their deviation from the predetermined trajectory, reduced drive efficiency, and possible failures. This study investigates this problem using terramechanics analysis of the wheel-soil interaction. First, a slope-based wheel-soil interaction terramechanics model is built, and an online slip coordinated algorithm is designed based on the goal of optimal drive efficiency. An equation of state is established using the coordinated slip as the desired input and the actual slip as a state variable. To improve the robustness and adaptability of the control system, an adaptive neural network is designed. Analytical results and those of a simulation using Vortex demonstrate the significantly improved mobile performance of the WMR using the proposed control system. PMID:25276849

  18. Nonlinear dynamical triggering of slow slip

    SciTech Connect

    Johnson, Paul A; Knuth, Matthew W; Kaproth, Bryan M; Carpenter, Brett; Guyer, Robert A; Le Bas, Pierre - Yves; Daub, Eric G; Marone, Chris

    2010-12-10

    Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads ({approx}1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred

  19. Experiment system of LAMOST active optics

    NASA Astrophysics Data System (ADS)

    Cui, Xiangqun; Su, Ding; Li, Guoping; Yao, Zhengqiu; Zhang, Zhengcao; Li, Yeping; Zhang, Yong; Wang, You; Xu, Xinqi; Wang, Hai

    2004-10-01

    Active optics is the most difficult part in LAMOST project. Especially for the segmented reflecting Schmidt plate Ma, in which both segmented mirror active optics and thin mirror (or deformable mirror) active optics are applied. To test and optimize the thin mirror active optics of Ma, and to approach the reality of operating environment of the telescope, an outdoor experiment system has been established. This experiment system is also a `small LAMOST" with one sub-mirror of the primary mirror Mb and one sub-mirror of the Schmidt plate Ma, and with full scale in spacing (40 meters) between Ma and Mb. many parts of LAMOST were tested in the experiment system except segmented mirror active optics. Especially for force actuators, thin mirror support system, friction driving of the alt-azimuth mounting and its control system, wave front test along such a long optical path. This paper presents the experiment system, research and developments, and some experiment results.

  20. Modeling Cytoskeletal Active Matter Systems

    NASA Astrophysics Data System (ADS)

    Blackwell, Robert

    Active networks of filamentous proteins and crosslinking motor proteins play a critical role in many important cellular processes. One of the most important microtubule-motor protein assemblies is the mitotic spindle, a self-organized active liquid-crystalline structure that forms during cell division and that ultimately separates chromosomes into two daughter cells. Although the spindle has been intensively studied for decades, the physical principles that govern its self-organization and function remain mysterious. To evolve a better understanding of spindle formation, structure, and dynamics, I investigate course-grained models of active liquid-crystalline networks composed of microtubules, modeled as hard spherocylinders, in diffusive equilibrium with a reservoir of active crosslinks, modeled as hookean springs that can adsorb to microtubules and and translocate at finite velocity along the microtubule axis. This model is investigated using a combination of brownian dynamics and kinetic monte carlo simulation. I have further refined this model to simulate spindle formation and kinetochore capture in the fission yeast S. pombe. I then make predictions for experimentally realizable perturbations in motor protein presence and function in S. pombe.

  1. A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

    DOE PAGESBeta

    Zeng, Y.; Hunter, A.; Beyerlein, I. J.; Koslowski, M.

    2015-09-14

    In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τcrit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τcrit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results show that themore » value of τcrit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τcrit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τcrit values.« less

  2. A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

    SciTech Connect

    Zeng, Y.; Hunter, A.; Beyerlein, I. J.; Koslowski, M.

    2015-09-14

    In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τcrit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τcrit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results show that the value of τcrit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τcrit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τcrit values.

  3. High speed hybrid active system

    NASA Astrophysics Data System (ADS)

    Gonzalez, Ignacio F.; Chang, Fu-Kuo; Qing, Peter X.; Kumar, Amrita; Zhang, David

    2005-05-01

    A novel piezoelectric/fiber-optic system is developed for long-term health monitoring of aerospace vehicles and structures. The hybrid diagnostic system uses the piezoelectric actuators to input a controlled excitation to the structure and the fiber optic sensors to capture the corresponding structural response. The aim of the system is to detect changes in structures such as those found in aerospace applications (damage, cracks, aging, etc.). This system involves the use of fiber Bragg gratings, which may be either bonded to the surface of the material or embedded within it in order to detect the linear strain component produced by the excitation waves generate by an arbitrary waveform generator. Interrogation of the Bragg gratings is carried out using a high speed fiber grating demodulation unit and a high speed data acquisition card to provide actuation input. With data collection and information processing; is able to determine the condition of the structure. The demands on a system suitable for detecting ultrasonic acoustic waves are different than for the more common strain and temperature systems. On the one hand, the frequency is much higher, with typical values for ultrasonic frequencies used in non-destructive testing ranging from 100 kHz up to several MHz. On the other hand, the related strain levels are much lower, normally in the μstrain range. Fiber-optic solutions for this problem do exist and are particularly attractive for ultrasonic sensing as the sensors offer broadband detection capability.

  4. Contribution of high resolution PLEIADES imagery to active faults analysis. Case study of the Longriba Fault System, eastern Tibet.

    NASA Astrophysics Data System (ADS)

    Ansberque, Claire; Bellier, Olivier; Godard, Vincent; Lasserre, Cécile; Wang, Mingming; Xu, Xiwei; Tan, Xibin

    2015-04-01

    High resolution imagery has largely developed during those two last decades allowing the possibility to observe and quantify geological and geomorphological features ranging from meter to few centimeters. Active tectonic and geomorphological studies have greatly benefited from the systematic use of such data. For that reason, we tested the contribution of PLEAIDES images to the analysis of an active strike-slip fault system in eastern Tibet. We used 50 cm resolution panchromatic PLEIADES images in order to map active fault segmentation, localize offsets of geomorphic markers and quantify vertical and horizontal displacements. We propose a preliminary study using PLEIADES images along the Longriba Fault System (LFS). The LFS, located at the eastern Tibetan Plateau margin, is constituted of two NW-SE dextral strike-slip and parallel fault zones: Longriqu and Maoergai, 80 and 120 km-long, respectively. It accommodates ~4 mm/yr dextral slip and very few vertical motion. We used stereo-pairs to build relative Digital Elevation Models (DEMs) (without ground control points) with a horizontal resolution ranging from 2 to 5 m, in order to understand the geometry of the system. We measured fault segments with lengths ranging from a hundred meters to several kilometers which are relatively close from each others, and several offsets of geomorphic markers (alluvial fans, ridges, rivers) ranging from a few meters to ~40 m. According to the segmentation deduced from those results we suggest that the fault has a high seismic potential (>Mw7.0) and that probably many surface rupturing earthquakes occurred along the LFS over the Holocene.

  5. Magmatically triggered slow slip at Kilauea Volcano, Hawaii.

    PubMed

    Brooks, Benjamin A; Foster, James; Sandwell, David; Wolfe, Cecily J; Okubo, Paul; Poland, Michael; Myer, David

    2008-08-29

    We demonstrate that a recent dike intrusion probably triggered a slow fault-slip event (SSE) on Kilauea volcano's mobile south flank. Our analysis combined models of Advanced Land Observing Satellite interferometric dike-intrusion displacement maps with continuous Global Positioning System (GPS) displacement vectors to show that deformation nearly identical to four previous SSEs at Kilauea occurred at far-field sites shortly after the intrusion. We model stress changes because of both secular deformation and the intrusion and find that both would increase the Coulomb failure stress on possible SSE slip surfaces by roughly the same amount. These results, in concert with the observation that none of the previous SSEs at Kilauea was directly preceded by intrusions but rather occurred during times of normal background deformation, suggest that both extrinsic (intrusion-triggering) and intrinsic (secular fault creep) fault processes can lead to SSEs. PMID:18755967

  6. A silent slip event on the deeper Cascadia subduction interface.

    PubMed

    Dragert, G; Wang, K; James, T S

    2001-05-25

    Continuous Global Positioning System sites in southwestern British Columbia, Canada, and northwestern Washington state, USA, have been moving landward as a result of the locked state of the Cascadia subduction fault offshore. In the summer of 1999, a cluster of seven sites briefly reversed their direction of motion. No seismicity was associated with this event. The sudden displacements are best explained by approximately 2 centimeters of aseismic slip over a 50-kilometer-by-300-kilometer area on the subduction interface downdip from the seismogenic zone, a rupture equivalent to an earthquake of moment magnitude 6.7. This provides evidence that slip of the hotter, plastic part of the subduction interface, and hence stress loading of the megathrust earthquake zone, can occur in discrete pulses. PMID:11313500

  7. Slip propagation in epitaxial Mo (011) studied by low-energy electron microscopy

    NASA Astrophysics Data System (ADS)

    Mundschau, M.; Swięch, W.; Durfee, C. S.; Flynn, C. P.

    1999-10-01

    We report observations of slip processes in epitaxial films of Mo (011) grown on sapphire by molecular beam epitaxy. Low-energy electron microscopy is employed to follow the time evolution of the screw dislocation, the interfacial dislocation, and the surface step edge structure through which the slip takes place. Under certain conditions the dislocation system is observed to trap briefly as it meets successive surface steps.

  8. The morphology of strike-slip faults - Examples from the San Andreas Fault, California

    NASA Technical Reports Server (NTRS)

    Bilham, Roger; King, Geoffrey

    1989-01-01

    The dilatational strains associated with vertical faults embedded in a horizontal plate are examined in the framework of fault kinematics and simple displacement boundary conditions. Using boundary element methods, a sequence of examples of dilatational strain fields associated with commonly occurring strike-slip fault zone features (bends, offsets, finite rupture lengths, and nonuniform slip distributions) is derived. The combinations of these strain fields are then used to examine the Parkfield region of the San Andreas fault system in central California.

  9. Segmentation and kinematics of the Kazerun fault system (southern Iran): Implications for active deformation partitioning within the Zagros fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Authemayou, C. A.; Bellier, O. B.; Chardon, D. C.; Malekzade, Z. M.; Abbassi, M. A.

    2003-04-01

    Iran is located within the interaction zone between the Arabian and Eurasian plates that currently converge at 30 mm/yr. Since the Miocene, continental collision resulted in the formation of the NW-trending Zagros fold-and-thrust belt that accommodates c.a. 10 mm/yr of NNE-trending shortening. The southeastern part of the thrust belt is affected by the north-trending, right lateral Kazerun Fault System (KFS) stretching from the Main Reverse Fault (i.e., the back-stop of the fold-and-thrust belt) in the vicinity of Borujen, in the North, to the Persian Gulf coast near Kormuj, in the south. Reconnaissance tectonic and geomorphic observations, combined with SPOT satellite image analyses allows characterising the KFS active trace geometry and kinematics as well as its relations with the folds and the thrust faults. This further allows evaluating the transfer process from right-lateral slip along the KSF to the fold-and-thrust system. The KFS consists in three North-trending fault zones of equivalent lengths (100 km) that show evidence for a northward increasing activity. The southern terminations of the fault zones are bent towards SE strikes and are generally connected westward with WNW-trending thrusts and ramp anticlines. Those terminations display a horsetail splay fault geometry associated with an eastward decrease of both the strike-slip and dip-slip component of finite offsets. Fault slip-vectors analyses indicate a consistent right-lateral strike-slip tectonic regime all along the KFS associated with a regionally homogeneous NNE-trending 1 direction. The central and northern fault zones show evidence for systematic Quaternary right-lateral offsets of geomorphic features such as stream beds and alluvial fans, as well as shutter ridges and faceted spurs. The northern termination of the KFS shows the most obvious criteria for active slip and the highest geomorphic offsets. This fault zone connects the southeastern tip of the Main Recent Fault, the major active

  10. San Andreas-sized Strike-slip Fault on Europa

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This mosaic of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, about the size of the California portion of the San Andreas fault, which runs from the California-Mexico border north to the San Francisco Bay.

    In a strike-slip fault, two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. Overall motion along the fault seems to have followed a continuous narrow crack along the feature's entire length, with a path resembling steps on a staircase crossing zones that have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. The fault's opposite sides can be reconstructed like a puzzle, matching the shape of the sides and older, individual cracks and ridges broken by its movements.

    [figure removed for brevity, see original site]

    The red line marks the once active central crack of the fault. The black line outlines the fault zone, including material accumulated in the regions which have been pulled apart.

    Bends in the fault have allowed the surface to be pulled apart. This process created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling-apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, in Death Valley and the Dead Sea. In those cases, the pulled-apart regions can include upwelled materials, but may be filled mostly by sedimentary and eroded material from above.

    One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. Tidal tension

  11. Slow earthquakes, preseismic velocity changes, and the origin of slow frictional stick-slip.

    PubMed

    Kaproth, Bryan M; Marone, C

    2013-09-13

    Earthquakes normally occur as frictional stick-slip instabilities, resulting in catastrophic failure and seismic rupture. Tectonic faults also fail in slow earthquakes with rupture durations of months or more, yet their origin is poorly understood. Here, we present laboratory observations of repetitive, slow stick-