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Showing papers on "Slip (materials science) published in 2011"


Journal ArticleDOI
24 Mar 2011-Nature
TL;DR: It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved, according to a large set of published and unpublished experiments.
Abstract: A review of about 300 published and unpublished rock friction experiments that reproduce seismic slip conditions suggests that a significant decrease in friction occurs at high slip rate. Extrapolating the experimental data to conditions that are typical of earthquake nucleation depths, the authors conclude that faults are lubricated during earthquakes, irrespective of the fault rock composition or specific weakening mechanism involved. This study reviews a large set of fault friction experiments and finds that a significant decrease in friction occurs at high slip rate. Extrapolating the experimental data to conditions typical of earthquake nucleation depths, it is concluded that faults are lubricated during earthquakes, irrespective of the fault rock composition or specific weakening mechanism involved. The determination of rock friction at seismic slip rates (about 1 m s−1) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip1. Given the difficulty in determining friction by seismological methods1, elucidating constraints are derived from experimental studies2,3,4,5,6,7,8,9. Here we review a large set of published and unpublished experiments (∼300) performed in rotary shear apparatus at slip rates of 0.1–2.6 m s−1. The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built4,5,6, quartz-built3 and carbonate-built7,8) rocks and non-cohesive rocks (clay-rich9, anhydrite, gypsum and dolomite10 gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger11,12 a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates13,14 suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7–15 km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved.

729 citations


Journal ArticleDOI
21 Jul 2011-Nature
TL;DR: The Tohoku-Oki earthquake reminds us of the potential for Mw ≈ 9 earthquakes to occur along other trench systems, even if no past evidence of such events exists, and it is imperative that strain accumulation be monitored using a space geodetic technique to assess earthquake potential.
Abstract: Detailed analysis of Global Positioning System data from Japan's Geospatial Information Authority network provides a record of coseismic and postseismic slip distribution on the megathrust fault where the magnitude-9.0 Tohoku-Oki earthquake occurred on 11 March 2011. The coseismic slip area stretches some 400 kilometres along the Japan trench, matching the area of the preseismic locked zone. Afterslip is now overlapping the coseismic slip area and expanding into the surrounding regions. The authors conclude that such geodetic data could help to improve the forecasting of earthquake potential along other subduction zones. In the accompanying News & Views, Jean-Philippe Avouac discusses current models for assessing seismic hazard. Most large earthquakes occur along an oceanic trench, where an oceanic plate subducts beneath a continental plate. Massive earthquakes with a moment magnitude, Mw, of nine have been known to occur in only a few areas, including Chile, Alaska, Kamchatka and Sumatra. No historical records exist of a Mw = 9 earthquake along the Japan trench, where the Pacific plate subducts beneath the Okhotsk plate, with the possible exception of the ad 869 Jogan earthquake1, the magnitude of which has not been well constrained. However, the strain accumulation rate estimated there from recent geodetic observations is much higher than the average strain rate released in previous interplate earthquakes2,3,4,5,6. This finding raises the question of how such areas release the accumulated strain. A megathrust earthquake with Mw = 9.0 (hereafter referred to as the Tohoku-Oki earthquake) occurred on 11 March 2011, rupturing the plate boundary off the Pacific coast of northeastern Japan. Here we report the distributions of the coseismic slip and postseismic slip as determined from ground displacement detected using a network based on the Global Positioning System. The coseismic slip area extends approximately 400 km along the Japan trench, matching the area of the pre-seismic locked zone4. The afterslip has begun to overlap the coseismic slip area and extends into the surrounding region. In particular, the afterslip area reached a depth of approximately 100 km, with Mw = 8.3, on 25 March 2011. Because the Tohoku-Oki earthquake released the strain accumulated for several hundred years, the paradox of the strain budget imbalance may be partly resolved. This earthquake reminds us of the potential for Mw ≈ 9 earthquakes to occur along other trench systems, even if no past evidence of such events exists. Therefore, it is imperative that strain accumulation be monitored using a space geodetic technique to assess earthquake potential.

694 citations


Journal ArticleDOI
17 Jun 2011-Science
TL;DR: Detailed geophysical measurements reveal features of the 2011 Tohoku-Oki megathrust earthquake and suggest the need to consider the potential for a future large earthquake just south of this event.
Abstract: Geophysical observations from the 2011 moment magnitude (M_w) 9.0 Tohoku-Oki, Japan earthquake allow exploration of a rare large event along a subduction megathrust. Models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places. Sources of high-frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip. Relative to the M_w 8.8 2010 Maule, Chile earthquake, the Tohoku-Oki earthquake was deficient in high-frequency seismic radiation-a difference that we attribute to its relatively shallow depth. Estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event.

691 citations


Journal ArticleDOI
TL;DR: In this paper, the authors focused on understanding the mechanisms for ductility improvement by microstructure analysis, texture analysis and slip trace analysis based on electron backscatter diffraction and transmission electron microscopy.

662 citations


Journal ArticleDOI
17 Jun 2011-Science
TL;DR: Finite-source imaging reveals that the rupture consisted of a small initial phase, deep rupture for up to 40 seconds, extensive shallow rupture at 60 to 70 seconds, and continuing deep rupture lasting more than 100 seconds, which may have enabled large shallow slip near the trench.
Abstract: Strong spatial variation of rupture characteristics in the moment magnitude (Mw) 9.0 Tohoku-Oki megathrust earthquake controlled both the strength of shaking and the size of the tsunami that followed. Finite-source imaging reveals that the rupture consisted of a small initial phase, deep rupture for up to 40 seconds, extensive shallow rupture at 60 to 70 seconds, and continuing deep rupture lasting more than 100 seconds. A combination of a shallow dipping fault and a compliant hanging wall may have enabled large shallow slip near the trench. Normal faulting aftershocks in the area of high slip suggest dynamic overshoot on the fault. Despite prodigious total slip, shallower parts of the rupture weakly radiated at high frequencies, whereas deeper parts of the rupture radiated strongly at high frequencies.

575 citations


Journal ArticleDOI
TL;DR: In this paper, the critical resolved shear stresses (CRSSs) of slip and twinning in magnesium crystals, as a function of temperature, under conditions of imposed strains, were characterized by systematic electron backscatter diffraction orientation maps.

554 citations


Journal ArticleDOI
TL;DR: Tsunami waveform inversion for the 11 March, 2011, off the Pacific coast of Tohoku Earthquake (M 9.0) indicates that the source of the largest tsunami was located near the axis of the Japan trench as discussed by the authors.
Abstract: Tsunami waveform inversion for the 11 March, 2011, off the Pacific coast of Tohoku Earthquake (M 9.0) indicates that the source of the largest tsunami was located near the axis of the Japan trench. Ocean-bottom pressure, and GPS wave, gauges recorded two-step tsunami waveforms: a gradual increase of sea level (~2 m) followed by an impulsive tsunami wave (3 to 5 m). The slip distribution estimated from 33 coastal tide gauges, offshore GPS wave gauges and bottom-pressure gauges show that the large slip, more than 40 m, was located along the trench axis. This offshore slip, similar but much larger than the 1896 Sanriku “tsunami earthquake,” is responsible for the recorded large impulsive peak. Large slip on the plate interface at southern Sanriku-oki (~30 m) and Miyagi-oki (~17 m) around the epicenter, a similar location with larger slip than the previously proposed fault model of the 869 Jogan earthquake, is responsible for the initial water-level rise and, presumably, the large tsunami inundation in Sendai plain. The interplate slip is ~10 m in Fukushima-oki, and less than 3 m in the Ibaraki-oki region. The total seismic moment is estimated as 3.8 × 1022 N m (Mw = 9.0).

496 citations


Journal ArticleDOI
01 Dec 2011-EPL
TL;DR: In this paper, the authors describe the slippery behaviour of textured solids filled with oil, on which other liquids are found to slip and be removed easily, and illustrate the concept by two examples, namely the lotus effect (removal of dust by mobile drops) and the coffee stain effect.
Abstract: We describe the slippery behaviour of textured solids filled with oil, on which other liquids are found to slip and be removed easily. We describe the criteria for achieving this slippery behaviour, and illustrate the concept by two examples, namely the lotus effect (removal of dust by mobile drops) and the coffee stain effect.

425 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that the atomic structure of the interface leads to low interface shear strength in non-coherent fcc-bcc nanolayered composites such as Cu-Nb.
Abstract: Recent advances in the fundamental understanding of the deformation mechanisms in metallic multilayers are reviewed. The strength of metallic multilayers increases with decreasing layer thickness and reaches a maximum at layer thickness of a couple of nanometers. The unit processes of slip transmission across the interphase boundary, without the mechanical advantage of a dislocation pile-up, are critical in determining the maximum flow strengths of multilayers. For the case of non-coherent fcc–bcc nanolayered composites such as Cu–Nb, we show that the atomic structure of the interface leads to low interface shear strength. The stress field of a glide dislocation approaching the interface locally shears the interface, resulting in dislocation core spreading and trapping in the interface plane. Glide dislocation trapping at the weak interface via core spreading is thus the key unit process that determines the interface barrier to slip transmission. The maximum strength achieved in a non-coherent multilayer can be tailored by the shear strength of the interface. The role of the atomic structure of the interface in promoting room temperature climb at interfaces and its implications in dislocation recovery is highlighted. Experimental validation of the model predictions is discussed.

384 citations


Journal ArticleDOI
17 Jun 2011-Science
TL;DR: Using data from Global Positioning System networks in Central Chile to infer the static deformation and the kinematics of the 2010 moment magnitude 8.8 Maule megathrust earthquake, it is found that rupture reached shallow depths, probably extending up to the trench.
Abstract: Large earthquakes produce crustal deformation that can be quantified by geodetic measurements, allowing for the determination of the slip distribution on the fault. We used data from Global Positioning System (GPS) networks in Central Chile to infer the static deformation and the kinematics of the 2010 moment magnitude ( M w) 8.8 Maule megathrust earthquake. From elastic modeling, we found a total rupture length of ~500 kilometers where slip (up to 15 meters) concentrated on two main asperities situated on both sides of the epicenter. We found that rupture reached shallow depths, probably extending up to the trench. Resolvable afterslip occurred in regions of low coseismic slip. The low-frequency hypocenter is relocated 40 kilometers southwest of initial estimates. Rupture propagated bilaterally at about 3.1 kilometers per second, with possible but not fully resolved velocity variations.

359 citations


Journal ArticleDOI
TL;DR: In this article, the effect of precipitates of different shape and habit on the basal, prismatic and { 1 0 1 ¯ 2 } twinning deformation systems in magnesium has been calculated.

Journal ArticleDOI
TL;DR: In this paper, the authors introduced a methodology to calculate the energy barriers during slip-GB interaction, in concurrence with the generalized stacking fault energy curve for slip in a perfect face-centered cubic material.

Journal ArticleDOI
TL;DR: In this paper, friction stir processing was applied to a magnesium alloy to generate various grain sizes with the same intense basal texture, and subsequent tensile deformation along two orthogonal directions by easy activation or inhibition of basal slip followed the Hall-Petch relationship between yield stress and grain size in both directions.

Journal ArticleDOI
TL;DR: In this article, a least-squares inversion of teleseismic P-waves was used to estimate fault displacements near the upper plate of the Tohoku megathrust.
Abstract: The 11 March 2011 off the Pacific coast of Tohoku (Mw 9.0) Earthquake ruptured a 200 km wide megathrust fault, with average displacements of ~15–20 m. Early estimates of the co-seismic slip distribution using seismic, geodetic and tsunami observations vary significantly in the placement of slip, particularly in the vicinity of the trench. All methods have difficulty resolving the up-dip extent of rupture; onshore geodetic inversions have limited sensitivity to slip far offshore, seismic inversions have instabilities in seismic moment estimation as subfault segments get very shallow, and tsunami inversions average over the total region of ocean bottom uplift. Seismic wave estimates depend strongly on the velocity structure used in the model, which affects both seismic moment estimation and inferred mapping to slip. We explore these ideas using a least-squares inversion of teleseismic P-waves that yields surprisingly large fault displacements (up to ~60 m) at shallow depth under a protrusion of the upper plate into the trench. This model provides good prediction of GPS static displacements on Honshu. We emphasize the importance of poorly-constrained rigidity variations with depth for estimating fault displacement near the trench. The possibility of large slip at very shallow depth holds implications for up-dip strain accumulation and tsunamigenic earthquake potential of megathrusts elsewhere.

Journal ArticleDOI
TL;DR: In this article, the role of dislocation slip in superelastic deformation of thin Ni-Ti wires containing various nanograined microstructures was investigated by tensile cyclic loading with in situ evaluation of electric resistivity.

Journal ArticleDOI
01 Jan 2011-Geology
TL;DR: In this article, the authors studied the relationship between frictional strength and friction rate dependence for a wide range of constituent minerals relevant to natural faults and found that frictional velocity dependence evolves systematically with shear strain.
Abstract: A fundamental problem in fault mechanics is whether slip instability associated with earthquake nucleation depends on absolute fault strength. We present laboratory experimental evidence for a systematic relationship between frictional strength and friction rate dependence, one of the key parameters controlling stability, for a wide range of constituent minerals relevant to natural faults. All of the frictionally weak gouges (coefficient of sliding friction, μ < 0.5) are composed of phyllosilicate minerals and exhibit increased friction with slip velocity, known as velocity-strengthening behavior, which suppresses frictional instability. In contrast, fault gouges with higher frictional strength exhibit both velocity-weakening and velocity-strengthening frictional behavior. These materials are dominantly quartzofeldspathic in composition, but in some cases include certain phyllosilicate-rich gouges with high friction coefficients. We also find that frictional velocity dependence evolves systematically with shear strain, such that a critical shear strain is required to allow slip instability. As applied to tectonic faults, our results suggest that seismic behavior and the mode of fault slip may evolve predictably as a function of accumulated offset.

Journal ArticleDOI
TL;DR: In this article, the authors derived the focal mechanism and slip history of the 2011 Mw 9.1 off the Pacific coast of Tohoku, Japan earthquake from teleseismic body and surface waves.
Abstract: Focal mechanism and slip history of the 2011 Mw 9.1 off the Pacific coast of Tohoku, Japan earthquake were derived rapidly from teleseismic body and surface waves. Multiple double couples (MDC) analysis was first conducted using 1-hour long period seismic waves, yielding a single double couple with a seismic moment of 5.06×1022 N m, whose low angle nodal plane orients 199° and dips 10° west. Spatiotemporal rupture history was then constrained using both broadband body waves and long period seismic waves. The solution was updated twice in three days. Our preferred model, which based on the MDC fault plane, local JMA hypocenter and calibrated alignments of body and surface waves, revealed a complex rupture process. The rupture initiated slowly at a depth of 23 km. It first propagated in downdip and bilaterally directions along the subduction interface for 45 s and then broke a 80 km by 250 km near trench asperity in the up-dip direction and produced up to 60 m slip. The fault plane below the hypocenter had two more subevents, occurring in 70–95 s and 110–160 s, respectively. The total seismic moment was 5.8 × 1022 N m. The abnormal high slip near the trench suggests a recurrence interval larger than 500 yr.

Journal ArticleDOI
TL;DR: In this paper, an ocean-bottom pressure gauge was installed before the 2011 Tohoku-Oki earthquake on a frontal wedge, which formed an uplift system near the Japan Trench.
Abstract: [1] We report an uplift of 5 m with a horizontal displacement of more than 60 m due to the 2011 Tohoku-Oki earthquake. The uplift was measured by an ocean-bottom pressure gauge installed before the earthquake on a frontal wedge, which formed an uplift system near the Japan Trench. Horizontal displacements of the frontal wedge were measured using local benchmark displacements obtained by acoustic ranging before and after the earthquake. The average displacements at the frontal wedge were 58 m east and 74 m east-southeast. These results strongly suggest a huge coseismic slip beneath the frontal wedge on the plate boundary. The estimated magnitude of the slip along the main fault was 80 m near the trench. Our results suggest that the horizontal and vertical deformations of the frontal wedge due to the slip generated the tremendous tsunami that struck the coastal area of northeastern Japan.

Journal ArticleDOI
14 Oct 2011-Science
TL;DR: It is demonstrated that at fast, seismic slip rates, an extraordinary reduction in the friction coefficient of crustal silicate rocks results from intense “flash” heating of microscopic asperity contacts and the resulting degradation of their shear strengths.
Abstract: The sliding resistance of faults during earthquakes is a critical unknown in earthquake physics. The friction coefficient of rocks at slow slip rates in the laboratory ranges from 0.6 to 0.85, consistent with measurements of high stresses in Earth's crust. Here, we demonstrate that at fast, seismic slip rates, an extraordinary reduction in the friction coefficient of crustal silicate rocks results from intense "flash" heating of microscopic asperity contacts and the resulting degradation of their shear strengths. Values of the friction coefficient due to flash heating could explain the lack of an observed heat flow anomaly along some active faults such as the San Andreas Fault. Nearly pure velocity-weakening friction due to flash heating could explain how earthquake ruptures propagate as self-healing slip pulses.

Journal ArticleDOI
TL;DR: In this article, a physically-based model is developed to address slip in polycrystalline metals and alloys subjected to very high rates of deformation (104−108 s−1).

Journal ArticleDOI
TL;DR: In this paper, the authors invert teleseismic P waves and broadband Rayleigh wave observations with high-rate GPS recordings from Japan to characterize the Tohoku Earthquake.
Abstract: The 11 March 2011 Tohoku Earthquake ruptured the interplate boundary off-shore of east Japan, with fault displacements of up to 40 m and a rupture duration of 150–160 s. W-phase inversion indicates a moment of 3.9 × 1022 N m (Mw 9.0) and a centroid time of 71 s. We invert teleseismic P waves and broadband Rayleigh wave observations with high-rate GPS recordings from Japan to characterize the rupture. The resulting rupture model begins with a steady increase of moment rate for the first 80 s, and a rupture speed of 1.5 km/s. Then the rupture expands southwestward at a speed of about 2.5 km/s. The model’s primary slip is concentrated up-dip from the hypocenter, with significant displacement extending to the trench. The seaward location of large slip is consistent with estimates of the tsunami source area from regional and remote tsunami observations. The region with large slip is approximately 150-km wide by 300-km long, which is relatively compact compared with the 200-km wide, 500-km long aftershock region. The model’s initial updip rupture expansion and the location of most slip updip of the hypocenter differs from P-wave array back-projections, which map high-frequency radiation along the downdip of the hypocenter, closer to the coast.

Journal ArticleDOI
08 Dec 2011-Nature
TL;DR: The results of atomic force microscopy experiments are presented that show that frictional ageing arises from the formation of interfacial chemical bonds, and the large magnitude of ageing at the nanometre scale is quantitatively consistent with what is required to explain observations in macroscopic rock friction experiments.
Abstract: Earthquakes have long been recognized as being the result of stick-slip frictional instabilities. Over the past few decades, laboratory studies of rock friction have elucidated many aspects of tectonic fault zone processes and earthquake phenomena. Typically, the static friction of rocks grows logarithmically with time when they are held in stationary contact, but the mechanism responsible for this strengthening is not understood. This time-dependent increase of frictional strength, or frictional ageing, is one manifestation of the 'evolution effect' in rate and state friction theory. A prevailing view is that the time dependence of rock friction results from increases in contact area caused by creep of contacting asperities. Here we present the results of atomic force microscopy experiments that instead show that frictional ageing arises from the formation of interfacial chemical bonds, and the large magnitude of ageing at the nanometre scale is quantitatively consistent with what is required to explain observations in macroscopic rock friction experiments. The relative magnitude of the evolution effect compared with that of the 'direct effect'--the dependence of friction on instantaneous changes in slip velocity--determine whether unstable slip, leading to earthquakes, is possible. Understanding the mechanism underlying the evolution effect would enable us to formulate physically based frictional constitutive laws, rather than the current empirically based 'laws', allowing more confident extrapolation to natural faults.

Journal ArticleDOI
18 Feb 2011-Science
TL;DR: Observations show that one of the best-recorded large earthquakes to date, the 1999 moment magnitude 7.6 Izmit (Turkey) earthquake, was preceded by a seismic signal of long duration that originated from the hypocenter that consisted of a succession of repetitive seismic bursts, accelerating with time, and increased low-frequency seismic noise.
Abstract: Laboratory and theoretical studies suggest that earthquakes are preceded by a phase of developing slip instability in which the fault slips slowly before accelerating to dynamic rupture. We report here that one of the best-recorded large earthquakes to date, the 1999 moment magnitude (Mw) 7.6 Izmit (Turkey) earthquake, was preceded by a seismic signal of long duration that originated from the hypocenter. The signal consisted of a succession of repetitive seismic bursts, accelerating with time, and increased low-frequency seismic noise. These observations show that the earthquake was preceded for 44 minutes by a phase of slow slip occurring at the base of the brittle crust. This slip accelerated slowly initially, and then rapidly accelerated in the 2 minutes preceding the earthquake.

Journal ArticleDOI
TL;DR: Simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip, and this dichotomy might be purely coincidental.
Abstract: Understanding and predicting the behavior of water, especially in contact with various surfaces, is a scientific challenge. Molecular-level understanding of hydrophobic effects and their macroscopic consequences, in particular, is critical to many applications. Macroscopically, a surface is classified as hydrophilic or hydrophobic depending on the contact angle formed by a water droplet. Because hydrophobic surfaces tend to cause water slip whereas hydrophilic ones do not, the former surfaces can yield self-cleaning garments and ice-repellent materials whereas the latter cannot. The results presented herein suggest that this dichotomy might be purely coincidental. Our simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip. Further analysis provides details on the molecular mechanism responsible for this surprising result.

Journal ArticleDOI
TL;DR: In this article, both geodetic and seismic estimates of the coseismic rupture extent for the March 11, 2011 MW = 8.9-9.0 earthquake Tohoku-oki earthquake may be spatially correlated with regions of pre-seismic interplate coupling.
Abstract: [1] Imaging the extent to which the rupture areas of great earthquakes coincide with regions of pre-seismic interplate coupling is central to understanding patterns of strain accumulation and release through the earthquake cycle. Both geodetic and seismic estimates of the coseismic rupture extent for the March 11, 2011 MW = 8.9–9.0 earthquake Tohoku-oki earthquake may be spatially correlated (0.26 ± 0.05 to 0.82 ± 0.05) with a region estimated to be partially to fully coupled in the interseismic period preceding the earthquake, though there is substantial variation in the estimated distribution and magnitude of coseismic slip. The ∼400 km-long region estimated to have slipped ≥4 m corresponds to an area of the subduction zone interface that was coupled at ≥30% of long-term plate convergence rate, with peak slip near a region coupled ≥80%. The northern termination of rupture is collocated with a region of relatively low (<20%) interseismic coupling near the epicenter of the 1994 MW = 7.6 Sanriku-oki earthquake, and near a region of potential long-term low coupling or ongoing slow slip. Slip on the subduction interface beneath the coastline (40–50 km depth) is best constrained by the land-based GPS data and least constrained on the shallowest portion of the plate interface due to the ∼230 km distance between geodetic observations and the Japan trench.

Journal ArticleDOI
TL;DR: In this paper, the effects of partial slip on steady boundary layer stagnation-point flow of an incompressible fluid and heat transfer towards a shrinking sheet were analyzed using similarity transformation technique and then the self-similar equations were solved numerically using shooting method.

Journal ArticleDOI
TL;DR: In this article, the authors study dynamic rupture propagation on self-similar faults having root mean square (rms) height fluctuations of order 10 -3 to 10 -2 times the profile length.
Abstract: Observations demonstrate that faults are fractal surfaces with deviations from planarity at all scales. We study dynamic rupture propagation on self-similar faults having root mean square (rms) height fluctuations of order 10 -3 to 10 -2 times the profile length. Our 2D plane strain models feature strongly rate-weakening fault friction and off-fault Drucker–Prager viscoplasticity. The latter bounds otherwise unreasonably large stress concentrations in the vicinity of bends. Our choice of a cohesionless yield function prevents tensile stress states and thus fault opening. A consequence of strongly rate-weakening friction is the existence of a critical background stress level above which self-sustaining rupture propagation, in the form of self-healing slip pulses, first becomes possible. Around this level, at which natural faults are expected to operate, ruptures become extremely sensitive to fault roughness and exhibit substantial fluctuations in rupture velocity. Except for shallow inclinations of the maximum compressive stress to the fault (less than about 20°), the fluctuations are anticorrelated with the local fault slope. These accelerations and decelerations of the rupture, together with naturally emerging slip heterogeneity, excite waves of all wavelengths and result in ground acceleration spectra that are flat at high frequency, consistent with observed strong motion records.

Journal ArticleDOI
TL;DR: In this paper, the cyclic deformation behaviors of different kinds of face-centered cubic (fcc) single crystals, including copper, nickel, silver, as well as copper-aluminium, copper-zinc alloys in attempt to provide a historical perspective of the developments over the last several decades.

Journal ArticleDOI
TL;DR: In this paper, centroid moment tensors of earthquakes that occurred from 2003 to 2011 in and around the focal area of the 2011 Mw 9.0 megathrust earthquake in eastern Japan were estimated.
Abstract: We estimated centroid moment tensors of earthquakes that occurred from 2003 to 2011 in and around the focal area of the 2011 Mw 9.0 megathrust earthquake in eastern Japan. The result indicates that earthquakes occurring before the mainshock, which included foreshocks off Miyagi, were basically interplate earthquakes with thrust-type focal mechanisms. On the other hand, the aftershocks exhibited a variety of focal mechanisms. Interplate aftershocks with thrust focal mechanisms did not occur within the large coseismic slip area estimated from GPS data but instead occurred in the surrounding regions. This implies that slip could no longer occur in the coseismic slip area due to the large amount of stress release during the mainshock rupture, whereas the aftershocks in the surrounding regions were caused by a stress concentration in these regions due to the large co-seismic slip associated with the mainshock asperity. Normal-fault-type aftershocks were widely distributed in the overriding plate and the outer-rise of the Pacific Plate. These aftershocks may have been due to a tensional stress change caused by the coseismic slip. Thrust-fault-type aftershocks in the subducting Pacific Plate were also interpreted as being due to compressional stress change as a result of the coseismic slip.

Journal ArticleDOI
TL;DR: It is observed that both frequently discussed mechanisms, truncation of spiral dislocation sources and exhaustion of defects available within the specimen, contribute to high strengths and related size-effects in small volumes, suggesting that in the submicrometer range these mechanisms should be considered simultaneously rather than exclusively.
Abstract: A unique method for quantitative in situ nano- tensile testing in a transmission electron microscope employing focused ion beam fabricated specimens was developed. Experi- ments were performed on copper samples with minimum dimensions in the 100200 nm regime oriented for either single slip or multiple slip, respectively. We observe that both frequently discussed mechanisms, truncation of spiral disloca- tion sources and exhaustion of defects available within the specimen, contribute to high strengths and related size-effects insmallvolumes.Thissuggeststhatinthesubmicrometerrange these mechanisms should be considered simultaneously rather than exclusively.