Distribution of seismicity across strike‐slip faults in California

Powers, Peter M.; Jordan, Thomas H.

doi:10.1029/2008jb006234

Cited by 109 publications

(110 citation statements)

References 126 publications

(149 reference statements)

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“…This is partly evident in the clustering of events around P32 in Fig. 2 and has been documented in numerous studies (BUFE et al 1981;LUDWIN et al 1982;EBERHART-PHILLIPS and OPPENHEIMER 1984;OPPENHEIMER 1986;STARK 1992;ROMERO et al 1994;MAJER and PETER-SON 2007). Another type of evidence is the commonly found isotropic part of the static moment tensor of induced earthquakes as described in Fig.…”

Section: Extended Crack Modelmentioning

confidence: 76%

“…More than one slip surface is involved, different elements of the moment tensor have different time functions, and a volume change is generally present. However, in recent years there have been a number of studies of off-fault seismicity, which consists of the small earthquakes that are invariably found in a zone extending away from tectonic faults (see for instance POLIAKOV et al 2002;RICE et al 2005;VIESCA et al 2008;SAMMIS et al 2009;DIETERICH and SMITH 2009;POWERS and JORDAN 2010). Thus, while the induced earthquakes and extended crack model of this study may not be appropriate analogs for ordinary tectonic earthquakes, they may be more appropriate analogs for the off-fault seismicity that accompanies tectonic earthquakes.…”

Section: Figure 10mentioning

confidence: 80%

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A Source Model for Induced Earthquakes at the Geysers Geothermal Reservoir

Johnson

2014

Pure Appl. Geophys.

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Abstract-The results of a previous study on source mechanisms of small earthquakes at the Geysers geothermal reservoir in northern California are used to investigate an extended crack model for seismic events. The seismic events are characterized by their first-degree moment tensors and interpreted in terms of a model that is a combination of a shear crack and wing cracks. Solutions to both forward and inverse problems are obtained that can be used with either dynamic or static moment tensors. The model contains failure criteria, explains isotropic parts that are commonly observed in induced earthquakes, and produces estimates of crack dimensions and maximum amount of slip. Effects of fluid pressure are easily incorporated into the model as an effective stress. The model is applied to static moment tensors of 20 earthquakes that occurred during a controlled injection project in the northwest Geysers. For earthquakes in the moment magnitude range of 0.9-2.8, the model predicts shear crack radii in the range of 10-150 m, wing crack lengths in the range of 2-25 m, and maximum slips in the range of 0.3-1.1 cm. Only limited results are obtained for the time-dependence of the earthquake process, but the model is consistent with corner frequencies of the isotropic part of the moment tensor being greater than the deviatoric part and waveforms of direct p waves that become more emergent for larger events.

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Section: Extended Crack Modelmentioning

confidence: 76%

Section: Figure 10mentioning

confidence: 80%

A Source Model for Induced Earthquakes at the Geysers Geothermal Reservoir

Johnson

2014

Pure Appl. Geophys.

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“…Using the aftershock catalogue of Hauksson et al (2012), we compare our estimates with the distribution of seismicity around the main fault, which is another indicator of distributed damage in the host rock (Amitrano 2006;Powers & Jordan 2010). As shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…10(a), we select two profiles across the main rupture surrounding the southern antithetic fault to avoid any bias due to events located on this segment. Following Powers & Jordan (2010), we compute the horizontal density ν(x) of seismicity where x is the fault normal distance, and assume a power law decay of the form…”

Section: Discussionmentioning

confidence: 99%

Revisiting the 1992 Landers earthquake: a Bayesian exploration of co-seismic slip and off-fault damage

Gombert¹,

Duputel²,

Jolivet

et al. 2017

Geophysical Journal International

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S U M M A R YExisting models for the distribution of subsurface fault slip associated with the 1992 Landers, CA, earthquake (M w = 7.3) show significant dissimilarities. In particular, they exhibit different amounts of slip at shallow depths (<5 km). These discrepancies can be primarily attributed to the ill-posed nature of the slip inversion problem and to the use of physically unjustifiable smoothing or regularization constraints. In this study, we propose a new coseismic model obtained from the joint inversion of multiple observations in a relatively unregularized and fully Bayesian framework. We use a comprehensive data set including GPS, terrestrial geodesy, multiple SAR interferograms and co-seismic offsets from correlation of aerial images. These observations provide dense coverage of both near-and far-field deformation. To limit the impact of modelling uncertainties, we develop a 3-D fault geometry designed from field observations, co-seismic offsets and the distribution of aftershocks. In addition, we account for uncertainty in the assumed elastic structure used to compute the Green's functions. Our solution includes the ensemble of all plausible models that are consistent with our prior information and fit the available observations within data and prediction uncertainties. Using near-fault high-resolution ground deformation measurements and the density of aftershocks, we investigate the properties of the damage zone and its impact on the inferred slip at depth. We attribute a part of the inferred slip deficit at shallow depth to our models not including the impact of a damage zone associated with a reduction of shear modulus in the vicinity of the fault.

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“…Second, one could use the out of plane distribution of seismicity as a function of the fault thickness. As shown for faults in California, this distribution can be related to the stress variations owing to the fault roughness and thus can be interpreted as a quantification of the heterogeneity of the interface [Powers and Jordan (2010)]. In this sense, it would then be directly related to the L parameter introduced in our system.…”

Section: Velocity Burst Distribution B Vmentioning

confidence: 99%

Mechanical origin of b-value changes during stimulation of deep geothermal reservoirs

2015

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Background:The distribution of induced-earthquake magnitudes in deep geothermal reservoirs is a classical tool for monitoring reservoirs. It typically shows some important fluctuations through time and space. Despite being a very crude information (i.e., a scalar quantity) of very complex mechanical stress evolution, understanding these variations could still give us insights into the mechanics of the reservoir. Here, we analyze the output of a simple quasi-static physical model of a single fault and propose a new way to describe bursts that could be compared to seismic events. Methods: Our model is an elastic fiber bundle model describing multiple ruptures along a single major fault of the reservoir. It consists of a set of fibers with various strengths, arranged in a planar L × L two-dimensional array, linking together two elastic half-spaces. It mimics a fault zone with various asperities. During load, the fibers break quasi-statically according to a stress threshold distribution. Contrary to classical fiber bundle model, here, when a fiber breaks, it redistributes the load on the surviving fibers through long range elastic interactions. Interestingly, the elasticity of the half-spaces which changes the range of the stress distribution, characterizes two distinct regimes. In a stiff regime, we find an effective ductile deformation regime at large scale since the damage distribution is very difuse. Conversely in softer systems, the distance between two consecutive breaking fibers gets smaller and failure of the interface is localized, exhibiting an effective brittle regime. Results: We analyze two types of burst distributions: a classical one built from the statistics of the broken bonds during each failure step and a new one defines from a waiting time matrix of the fracture front propagation. The first one reproduces several known results for this type of model. The new one evidences the existence of effective creeping advances of the front with statistics that follow a Gutenberg-Richter distribution, in particular, in the ductile regime (stiff systems). Conclusions:We proposed a new definition of bursts in a fault model, based on the local fracture front velocity. We find that b v -values for the distribution of the velocity clusters are very consistent with Gutenberg-Richter distribution of induced seismicity. We link the b v -value fluctuations in the reservoirs to the influence of the velocity threshold level that could be related to recording limitation. b b -values obtained from the broken bond statistics are hardly comparable to seismic events because of the lack of space contiguousness of broken fibers during bursts. In the light of our results, we discuss the implications of b-value changes in geothermal reservoir in terms of fault asperities and normal stress evolution.

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Distribution of seismicity across strike‐slip faults in California

Cited by 109 publications

References 126 publications

A Source Model for Induced Earthquakes at the Geysers Geothermal Reservoir

A Source Model for Induced Earthquakes at the Geysers Geothermal Reservoir

Revisiting the 1992 Landers earthquake: a Bayesian exploration of co-seismic slip and off-fault damage

Mechanical origin of b-value changes during stimulation of deep geothermal reservoirs

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