Faults often separate materials with different elastic properties. Nonuniform slip on such faults induces a change in normal stress. That suggests the possibility of self‐sustained pulses [ Weertman , 1980] propagating at generalized Rayleigh wave speed even Coulomb constitutive law (i.e., constant coefficient friction) and remote driving shear stress that is arbitrarily less than corresponding frictional strength. Following Andrews Ben‐Zion [1997] (ABZ), we study numerically,...

We report the first consistent observations of rotational motions around a vertical axis induced by distant large earthquakes. It is standard in seismology to observe three components (up‐down, N‐S, E‐W) earthquake‐induced translational ground using inertial seismometers. However, only recently ring laser technology has provided required sensitivity for theoretically predicted part motion generated seismic waves wide distance range and frequency band. Here we show that rotations observed are...

It has been noted by theoretical seismologists for decades that—in addition to translations and strains—the rotational part of ground motions should also be recorded. is expected that collocated measurements rotations may (1) allow transformation translational seismograms the complete motion an observation point; (2) help further constrain rupture processes (3) provide additional hazard-relevant information earthquake engineers. The lack instrumental sensitivity used main obstacle observing...

We study a simple antiplane fault of finite length embedded in homogeneous, isotropic, elastic solid order to understand the origin seismic source heterogeneity presence nonlinear rate‐dependent friction. All mechanical properties medium and friction are assumed be homogeneous. Starting from heterogeneous initial stress distribution, we apply slowly increasing uniform load far simulate seismicity for more than 20,000 events, some cases. The style produced by this model is determined control...

Recently, ring laser technology has provided the first consistent obser- vations of rotational ground motions around a vertical axis induced by earthquakes. Consistent, in this context, implies that observed waveforms and amplitudes are compatible with collocated recordings translational motions. In partic- ular, transverse accelerations should be phase rotation rate their ratio proportional to local horizontal velocity assuming plane-wave propagation. The installed at Fundamentalstation...

We study the consequences of temporal stress perturbations on earthquake nucleation in a continuous fault model. Using two‐dimensional (2‐D) quasi‐dynamic model strike‐slip governed by rate‐and‐state friction law with depth variable properties, we show that dynamic triggering (due to pulses or wave packets), although allowed our results, is an exception rather than rule and should be limited understressed areas such as high pore pressures faults at very end their cycle. When periodic are...

We perform a numerical investigation of dynamic ruptures on bimaterial interface in 3-D with regularized slip-weakening friction and heterogeneous initial shear stress discuss the resulting strong ground motion. To isolate effects introduced by material contrast, we pairs simulations opposite orientations. show that for many parameter sets dynamics rupture propagation are significantly influenced broken symmetry due to contrast during propagation. The slip histories two events reversed...

We extended a high-order finite-difference scheme for the elastic SH-wave equation in axisymmetric media use on parallel computers with distributed memory architecture. Moreover, we derive an analytical description of implemented ring source and compare it quantitatively double couple source. The restriction to axisymmetry high performance PC networks allows computation synthetic seismograms at dominant periods down 2.5 s global mantle models. give our algorithm (SHaxi) its verification...

The recent availability of accurate observations rotational ground motions has reopened interest in understanding near-fault characteristics such the context strong motion and earthquake engineering.In order to investigate source structure-dependent variations motions, we simulate several M 7 earthquakes with varying scenarios on Newport-Inglewood (NI) fault embedded 3D Los Angeles basin using a finite-difference method frequency range up 0.5 Hz.We use precalculated database hundred...

This paper presents the stability analysis of a system sliding at low velocities (<100 μm⋅s−1) under periodically modulated normal load, preserving interfacial contact. Experiments clearly evidence that vibrations generally stabilize against stick-slip oscillations, least for modulation frequency much larger than one. The mechanical model L. Bureau, T. Baumberger, and C. Caroli validated on steady-state response system, is used to map its diagram. takes explicitly into account finite...

Although rotational seismology has progressed in recent decades, the links between ground motion and site soil conditions are poorly documented. New experiments were performed on Kefalonia Island (Greece) following two large earthquakes (M W = 6.0, M 5.9) early 2014 well-characterized sites (soft soil, V S30 ~ 250 m/s; rock, 830 m/s, being harmonic average shear-wave velocity 0 30 m depth). These led to six-component (three translations three rotations) datasets of hundreds well-recorded...

While of paramount importance in material science, the dynamics cracks still lacks a complete physical explanation. The transition from their slow creep behavior to fast propagation regime is notable key, as it leads full failure if size avalanche reaches that system. We here show simple thermodynamics approach can actually account for such complex crack dynamics, and particular non-monotonic force-velocity curves commonly observed mechanical tests on various materials. consider thermally...

The influence of normal and shear stress static perturbations on a strike‐slip fault is addressed the basis two‐dimensional continuous quasi‐dynamic model. Friction along plane described using rate‐and‐state friction law with depth variable properties. Normal result in similar effects terms earthquake triggering if Δτ − μ * Δσ constant, being amplitude fluctuations, respectively, constant which can be interpreted as coefficient Coulomb failure Therefore change ΔCFF = useful tool to account...

Abstract Ring-laser rotation sensors are contaminated by rotations around horizontal axes (also called tilts) through the vector product between local normal direction and of rate composed Earth’s ground rotations. In this study, we investigate theoretically cross-axis sensitivity estimate effects based on magnitude–amplitude relations to be expected for observations earthquakes teleseismic events. We tilt-ring-laser coupling rotational motions in P coda several past using tilt derived from...

We present a model for the thermally activated propagation of cracks in elastic matrices. The is considered as subcritical phenomenon, kinetics which described by an Arrhenius law. In this law, we take thermal evolution crack front into account, assuming that portion released mechanical energy transformed heat zone surrounding tip. show such leads to two-phase propagation: first phase at low velocity temperature elevation little effect and mainly governed load toughness medium, second...

It has recently been proposed by several authors that stress distribution around active faults may become critical spontaneously. Other believe heterogeneity is a permanent feature of fault planes. We test these ideas on simple but realistic model in the presence non-linear rate-dependent friction. find if friction increases with decreasing slip rate, becomes unstable at low rates generating supersonic healing phases lock prematurely. Locking turn produces heterogeneity. For containing...

Deterministic earthquake scenario simulations are playing an increasingly important role in seismic hazard and risk estimation. Our aim is to calculate a substantial number of different finite-source scenarios, embedded 3-D structure for particular fault or system, by pre-calculating numerical Green's functions (NGFs). A large divided into subfaults appropriate size which synthetic at the surface calculated stored. Consequently, ground motions from arbitrary kinematic sources can be...

Neither the Omori type of clustering prior to and following large earthquakes nor Gutenberg‐Richter distribution are reproducible by present continuous models. Discrete models, on other hand, give rise more complex closer realistic earthquake clustering. The objective this study is twofold: explore consequences spatial discreteness in time space activity a fault governed rate‐and‐state friction examine effect interaction between seismic slip aseismic creep aftershock sequences. To that end...

We perform numerical simulations of dynamic rupture propagation on a plane in model consisting two different elastic half spaces connected via planar frictional interface governed by regularized Coulomb friction. Therefore, ruptures this study are purely driven the presence material contrast. Ruptures nucleated fault using circular symmetric expanding increase pore‐pressure limited source region. show how wrinkle‐like pulse can mature also 3D case where we have mixing in‐plane and anti‐plane...

We study a simple antiplane fault of finite length embedded in homogeneous isotropic elastic solid to understand the origin seismic source heterogeneity presence nonlinear rate- and state-dependent friction. All mechanical properties medium friction are assumed homogeneous. Friction includes characteristic that is longer than grid size so our models have well-defined continuum limit. Starting from heterogeneous initial stress distribution, we apply slowly increasing uniform load far simulate...