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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 13:16:52 +0000Effects of non-linear weakening on earthquake source scalings
https://resolver.caltech.edu/CaltechAUTHORS:20120829-141351299
Authors: {'items': [{'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'J.-P.'}, 'orcid': '0000-0002-4827-7987'}]}
Year: 2005
An earthquake is usually modeled as an extension of the Dugdale approach: as in LEFM, fracture energy G_c
is completely spent in a relatively small region close to the crack tip, the process zone; and the fault strength
is described by a slip weakening law that reaches a residual level at a characteristic slip D_c. Beyond its
regularizing properties, slip weakening is a phenomenological fact of experimental rock mechanics. Recent
laboratory observations show that slip weakening can be a persistent process over large amounts of slip, in
contradiction to our usual view of a finite D_c. New seismological constraints from seismic nucleation phases
and from the scaling of radiated energy with magnitude, seem to point to a similar interpretation. Persistent
weakening can also be viewed as a lumped representation of off-fault
non linear processes occurring in the
wake of the process zone. On this basis, power law weakening laws have been proposed that feature a very
steep weakening rate in the short slip range followed by a long tailed, non linear, weakening process with
no characteristic slip. On the other hand there is growing interest in the apparent scaling of fault properties,
such as D_c and G_c, with earthquake size. This is a key issue in understanding how much can be learned
about large destructive earthquakes from the observation of smaller but more frequent ones and from laboratory
experiments. I explore here the possible effects of non linear strength drop on macroscopic earthquake source
parameters, such as magnitude, rupture size and radiated energy, and their interrelations
mainly via numerical
simulation of earthquake dynamics under a general family of empirical nonlinear
slip weakening laws.https://authors.library.caltech.edu/records/xecqy-cpy02Seismic Radiation From Simple Models of Earthquakes
https://resolver.caltech.edu/CaltechAUTHORS:20120830-095736559
Authors: {'items': [{'id': 'Madariaga-R', 'name': {'family': 'Madariaga', 'given': 'R.'}, 'orcid': '0000-0003-2524-9489'}, {'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'J. P.'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Adda-Bedia-M', 'name': {'family': 'Adda-Bedia', 'given': 'M.'}}]}
Year: 2006
DOI: 10.1029/170GM23
We review some basic features of shear wave generation and energy balance for a
2D anti plane rupture. We first study the energy balance for a flat fault, and for a fault
that contains a single localized kink. We determine an exact expression for the partition
between strain energy flow released from the elastic medium surrounding the
fault, radiated energy flow and energy release rate. This balance depends only on the
rupture speed and the residual stress intensity factor. When the fault contains a kink,
the energy available for fracture is reduced so that the rupture speed is reduced. When
rupture speed changes abruptly, the radiated energy flow also changes abruptly. As
rupture propagates across the kink, a shear wave is emitted that has a displacement
spectral content that decreases like ω^(-2) at high frequencies. We then use spectral elements
to model the propagation of an antiplane crack with a slip-weakening friction
law. Since the rupture front in this case has a finite length scale, the wave emitted by
the kink is smoothed at very high frequencies but its general behavior is similar to
that predicted by the simple sharp crack model. A model of a crack that has several kinks and wanders around a mean rupture directions, shows that kinks reduce the rupture speed along the average rupture direction of the fault. Contrary to flat fault models, a fault with kinks produces high frequency waves that are emitted every time the rupture front turns at a kink. Finally, we discuss the applicability of the present results to a 3D rupture model.https://authors.library.caltech.edu/records/yhcyz-qge60Properties of Dynamic Earthquake Ruptures With Heterogeneous Stress Drop
https://resolver.caltech.edu/CaltechAUTHORS:20120830-075047141
Authors: {'items': [{'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'J.-P.'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Ripperger-J', 'name': {'family': 'Ripperger', 'given': 'J.'}}, {'id': 'Mai-Paul-Martin', 'name': {'family': 'Mai', 'given': 'P. M.'}, 'orcid': '0000-0002-9744-4964'}]}
Year: 2006
DOI: 10.1029/170GM25
Earthquake rupture is a notoriously complex process, at all observable scales.
We introduce a simplified semi-dynamic crack model to investigate the connection
between the statistical properties of stress and those of macroscopic source
parameters such as rupture size, seismic moment, apparent stress drop and radiated
energy. Rupture initiation is treated consistently with nucleation on a linear slip-weakening
fault, whereas rupture propagation and arrest are treated according to
the Griffith criterion. The available stress drop is prescribed as a spatially correlated
random field and is shown to potentially sustain a broad range of magnitudes. By
decreasing the amplitude of the stress heterogeneities or increasing their correlation
length the distribution of earthquake sizes presents a transition from Gutenberg-
Richter to characteristic earthquake behavior. This transition is studied through a
mean-field analysis. The bifurcation to characteristic earthquake behavior is sharp,
reminiscent of a first-order phase transition. A lower roll-off magnitude observed
in the Gutenberg-Richter regime is shown to depend on the correlation length of the
available stress drop, rather than being a direct signature of the nucleation process.
More generally, we highlight the possible role of the stress correlation length scale
on deviations from earthquake source self-similarity. The present reduced model
is a building block towards understanding the effect of structural and dynamic
fault heterogeneities on the scaling of source parameters and on basic properties
of seismicity.https://authors.library.caltech.edu/records/sz7hb-w0y57Frontiers in Source Modeling for Near-Source Ground-Motion Prediction
https://resolver.caltech.edu/CaltechAUTHORS:20120829-131340033
Authors: {'items': [{'id': 'Mai-Paul-Martin', 'name': {'family': 'Mai', 'given': 'P. Martin'}, 'orcid': '0000-0002-9744-4964'}, {'id': 'Ripperger-J', 'name': {'family': 'Ripperger', 'given': 'J.'}}, {'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'J.-P.'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Hillers-G', 'name': {'family': 'Hillers', 'given': 'G.'}}]}
Year: 2006
Accurate prediction of the intensity and variability of strong ground motions
for future large earthquakes depends on our ability to simulate realistic earthquake source
models. While there has been considerable progress in characterizing the complexity of
earthquake ruptures, recent devastating earthquakes have exhibited rather unexpected
behavior. Moderate-size events occurred with surprisingly large ground motions, in
contrast to very large ruptures that showed relatively low ground motions in the frequency
range of 0.1 – 3.0 sec. These observations are at odds with standard ground-motion
attenuation relationships, and fundamentally challenge current strong-motion prediction
methods. A related issue is the question about the upper limits of near-source ground
motions. These topics can only be reconciled by considering the complexity of earthquake
faulting and the dynamic processes of rupture nucleation, propagation and arrest.
In this paper we discuss recent improvements to generate physically consistent
earthquake rupture models for strong-motion simulation. We combine simulated slip
distributions (realization of spatial random fields, consistent in scaling and spatial variability
with slip distributions of past earthquakes) with constraints on the rupture nucleation and
energy budget of earthquake rupture. Efficient stress-drop calculations in the spectral
domain serve as input to estimate the temporal evolution of the rupture process through a
set of empirical relationships derived from the analysis of spontaneous dynamic rupture
models. Long-term earthquake-cycle simulations with realistic variability in rate-and-state
friction parameters provide constraints on the generation, long-term behavior and
characterization of earthquake source complexity for fault zones at different evolutionary
stages. The pseudo-dynamic source characterization is inherently kinematic, but emulates the
most important characteristics of dynamic rupture. While the relationships between
dynamic source parameters are simplifications of the true complexity in rupture physics,
they help identify the interaction between source properties that are relevant for strong
ground motion prediction, and provide an improvement over purely kinematic models.https://authors.library.caltech.edu/records/fqz7d-eky37Comparison of Numerical Methods for Seismic Wave Propagation and Source Dynamics - the SPICE Code Validation
https://resolver.caltech.edu/CaltechAUTHORS:20120829-132714257
Authors: {'items': [{'id': 'Moczo-Peter', 'name': {'family': 'Moczo', 'given': 'Peter'}}, {'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'Jean Paul'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Kristek-Jozef', 'name': {'family': 'Kristek', 'given': 'Jozef'}, 'orcid': '0000-0002-2332-541X'}, {'id': 'Day-Steven-M', 'name': {'family': 'Day', 'given': 'Steven M.'}}, {'id': 'Kristekova-Miriam', 'name': {'family': 'Kristekova', 'given': 'Miriam'}}, {'id': 'Pazak-Pater', 'name': {'family': 'Pazak', 'given': 'Pater'}}, {'id': 'Galis-Martin', 'name': {'family': 'Galis', 'given': 'Martin'}, 'orcid': '0000-0002-5375-7061'}, {'id': 'Igel-Heiner', 'name': {'family': 'Igel', 'given': 'Heiner'}}]}
Year: 2006
The Southern California Earthquake Center (SCEC) organized the 3D
Numerical Simulation Code Validation Project for wave propagation in the past years.
Recently, SCEC organizes an earthquake source physics code validation/comparison
exercise. The goal of both efforts is to validate 3D earthquake simulation methods and
foster their application by engineering community. Development of the earthquake motion
numerical simulation methods is one of the primary goals of the Seismic Wave
Propagation and Imaging in Complex Media: a European Network (SPICE, www.spicertn.
org), the EU FP6 project. SPICE provides a reasonable platform for a code validation
effort in Europe. We present here the SPICE Code Validation. The intention is to create a
long-term basis for possible tests/comparisons/validation of numerical methods and codes
for the earthquake motion simulation. The basis should serve even after the SPICE project
is completed. Technically, the code validation process will be facilitated using the web-based
interface (http://www.nuquake.eu/SPICECVal/). The submitted solutions will be
evaluated and compared using quantitative misfit criteria based on the time-frequency
representation of the signals.https://authors.library.caltech.edu/records/08gdt-g6g72Upper limit on damage zone thickness controlled by seismogenic depth
https://resolver.caltech.edu/CaltechAUTHORS:20170509-142306720
Authors: {'items': [{'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'Jean Paul'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Mao-Xiaolin', 'name': {'family': 'Mao', 'given': 'Xiaolin'}, 'orcid': '0000-0002-8410-4629'}]}
Year: 2017
DOI: 10.1002/9781119156895.ch13
The thickness of fault damage zones, a characteristic length of the cross‐fault distribution of secondary fractures, significantly affects fault stress, earthquake rupture, ground motions, and crustal fluid transport. Field observations indicate that damage zone thickness scales with accumulated fault displacement at short displacements but saturates at a few hundred meters for displacements larger than a few kilometers. To explain this transition of scaling behavior, we conduct 3D numerical simulations of dynamic rupture with off‐fault inelastic deformation on long strike‐slip faults. We find that the distribution of coseismic inelastic strain is controlled by the transition from crack‐like to pulse‐like rupture propagation associated with saturation of the seismogenic depth. The yielding zone reaches its maximum thickness when the rupture becomes a stable pulse‐like rupture. Considering fracture mechanics theory, we show that seismogenic depth controls the upper bound of damage zone thickness on mature faults by limiting the efficiency of stress concentration near earthquake rupture fronts. We obtain a quantitative relation between limiting damage zone thickness, background stress, dynamic fault strength, off‐fault yield strength, and seismogenic depth, which agrees with first‐order field observations. Our results help link dynamic rupture processes with field observations and contribute to a fundamental understanding of damage zone properties.https://authors.library.caltech.edu/records/gyd50-sqd77Surface Rupture Effects on Earthquake Moment-Area Scaling Relations
https://resolver.caltech.edu/CaltechAUTHORS:20171220-111235529
Authors: {'items': [{'id': 'Luo-Yingdi', 'name': {'family': 'Luo', 'given': 'Yingdi'}, 'orcid': '0000-0002-1165-6107'}, {'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'Jean-Paul'}, 'orcid': '0000-0002-4827-7987'}, {'id': 'Miyakoshi-Ken', 'name': {'family': 'Miyakoshi', 'given': 'Ken'}}, {'id': 'Irikura-Kojiro', 'name': {'family': 'Irikura', 'given': 'Kojiro'}}]}
Year: 2017
DOI: 10.1007/978-3-319-72709-7_2
Empirical earthquake scaling relations play a central role in fundamental studies of earthquake physics and in current practice of earthquake hazard assessment, and are being refined by advances in earthquake source analysis. A scaling relation between seismic moment (M0) and rupture area (A) currently in use for ground motion prediction in Japan features a transition regime of the form M0–A2, between the well-recognized small (self-similar) and very large (W-model) earthquake regimes, which has counterintuitive attributes and uncertain theoretical underpinnings. Here, we investigate the mechanical origin of this transition regime via earthquake cycle simulations, analytical dislocation models and numerical crack models on strike-slip faults. We find that, even if stress drop is assumed constant, the properties of the transition regime are controlled by surface rupture effects, comprising an effective rupture elongation along-dip due to a mirror effect and systematic changes of the shape factor relating slip to stress drop. Based on this physical insight, we propose a simplified formula to account for these effects in M0–A scaling relations for strike-slip earthquakes.https://authors.library.caltech.edu/records/jxdx7-xc829Dynamic Rupture Simulations Based on the Characterized Source Model of the 2011 Tohoku Earthquake
https://resolver.caltech.edu/CaltechAUTHORS:20181108-111725055
Authors: {'items': [{'id': 'Tsuda-Kenichi', 'name': {'family': 'Tsuda', 'given': 'Kenichi'}}, {'id': 'Iwase-Satoshi', 'name': {'family': 'Iwase', 'given': 'Satoshi'}}, {'id': 'Uratani-Hiroaki', 'name': {'family': 'Uratani', 'given': 'Hiroaki'}}, {'id': 'Ogawa-Sachio', 'name': {'family': 'Ogawa', 'given': 'Sachio'}}, {'id': 'Watanabe-Takahide', 'name': {'family': 'Watanabe', 'given': 'Takahide'}}, {'id': 'Miyakoshi-Jun-ichi', 'name': {'family': 'Miyakoshi', 'given': "Jun'ichi"}}, {'id': 'Ampuero-J-P', 'name': {'family': 'Ampuero', 'given': 'Jean-Paul'}, 'orcid': '0000-0002-4827-7987'}]}
Year: 2018
DOI: 10.1007/s00024-016-1446-1
The 2011 Off the Pacific Coast of Tohoku earthquake (Tohoku earthquake, M w 9.0) occurred on the Japan Trench and caused a devastating tsunami. Studies of this earthquake have revealed complex features of its rupture process. In particular, the shallow parts of the fault (near the trench) hosted large slip and long period seismic wave radiation, whereas the deep parts of the rupture (near the coast) hosted smaller slip and strong radiation of short period seismic waves. Understanding such depth-dependent feature of the rupture process of the Tohoku earthquake is necessary as it may occur during future mega-thrust earthquakes in this and other regions. In this study, we investigate the "characterized source model" of the Tohoku earthquake through dynamic rupture simulations. This source model divides the fault plane into several parts characterized by different size and frictional strength (main asperity, background area, etc.) and is widely used in Japan for the prediction of strong ground motion and tsunami through kinematic rupture simulations. Our characterized source model of the Tohoku earthquake comprises a large shallow asperity with moderate frictional strength, small deep asperities with high frictional strength, a background area with low frictional strength, and an area with dynamic weakening close to the trench (low dynamic friction coefficient as arising from, e.g., thermal pressurization). The results of our dynamic rupture simulation reproduce the main depth-dependent feature of the rupture process of the Tohoku earthquake. We also find that the width of the area close to the trench (equal to the distance from the trench to the shallow asperity, interpreted as the size of the accretionary prism) and the presence of dynamic weakening in this area have a significant influence on the final slip distribution. These results are useful to construct characterized source models for other subduction zones with different scale of the accretionary prism, such as the Chile subduction zone and the Nankai Trough. Dynamic rupture simulations based on the characterized source model might provide useful insights for hazard assessment associated with future mega-thrust earthquakes.https://authors.library.caltech.edu/records/3twac-57948