Constant Stress Drop from Small to Great Earthquakes in Magnitude-Area Scaling

Shaw, Bruce E.

doi:10.1785/0120080006

Cited by 86 publications

(86 citation statements)

References 19 publications

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“…The average stress drops of segments F1, F2, F3 and F4 are 1.2, 2.7, 2.0 and 0.7 MPa, respectively, which fall within the typical range of earthquake stress drop by Allmann andShearer (2009) andShaw (2009). And the maximum stress drops of each segment are 4.2, 7.3, 8.3 and 5.8 MPa, respectively, which are consist with the other studies (e.g.…”

Section: Discussionsupporting

confidence: 85%

Coseismic slip in the 2010 Yushu earthquake (China), constrained by wide-swath and strip-map InSAR

Wen

Liu

et al. 2013

Nat. Hazards Earth Syst. Sci.

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Abstract. On 14 April 2010, an M w = 6.9 earthquake occurred in the Yushu county of China, which caused ∼3000 people to lose their lives. Integrated with the information from the observed surface ruptures and aftershock locations, the faulting pattern of this earthquake is derived from the descending wide-swath and ascending strip mode PALSAR data collected by ALOS satellite. We used a layered crustal model and stress drop smoothing constraint to infer the coseismic slip distribution. Our model suggests that the earthquake fault can be divided into four segments and the slip mainly occurs within the upper 12 km with a maximum slip of 2.0 m at depth of 3 km on the Jiegu segment. The rupture of the upper 12 km is dominated by left-lateral strike-slip motion. The relatively small slip along the SE region of Yushu segment suggests a slip deficit there. The inverted geodetic moment is approximately M w = 6.9, consistent with the seismological results. The average stress drop caused by the earthquake is about 2 MPa with a maximum stress drop of 8.3 MPa. Furthermore, the calculated static Coulomb stress changes in surrounding regions show increased Coulomb stress occurred in the SE region along the Yushu segment but with less aftershock, indicating an increased seismic hazard in this region after the earthquake.

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Section: Discussionsupporting

confidence: 85%

Coseismic slip in the 2010 Yushu earthquake (China), constrained by wide-swath and strip-map InSAR

Wen

Liu

et al. 2013

Nat. Hazards Earth Syst. Sci.

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“…HanksBakun08 ( (2) Shaw09mod (Shaw, 2009(Shaw, , 2013a: is a paleoseismically inferred event rate estimate, G sr specifies whether the rth rupture utilizes the sth subsection (0 or 1), and P paleo r is the probability that the rth rupture would be seen in a paleoseismic trench. This enables forcing the nucleation rate, R, in the mth magnitude bin to vary smoothly along a fault section, where the s − 1 and s 1 subsections are adjacent to the sth subsection.…”

Section: Slip Rate Balancing (Equation Set 1) Equation Set (1) Ofmentioning

confidence: 99%

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Field

Arrowsmith

Biasi

et al. 2014

Bulletin of the Seismological Society of America

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520

467

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The 2014 Working Group on California Earthquake Probabilities (WGCEP14) present the time-independent component of the Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3), which provides authoritative estimates of the magnitude, location, and time-averaged frequency of potentially damaging earthquakes in California. The primary achievements have been to relax fault segmentation and include multifault ruptures, both limitations of UCERF2. The rates of all earthquakes are solved for simultaneously and from a broader range of data, using a system-level inversion that is both conceptually simple and extensible. The inverse problem is large and underdetermined, so a range of models is sampled using an efficient simulated annealing algorithm. The approach is more derivative than prescriptive (e.g., magnitude-frequency distributions are no longer assumed), so new analysis tools were developed for exploring solutions. Epistemic uncertainties were also accounted for using 1440 alternative logic-tree branches, necessitating access to supercomputers. The most influential uncertainties include alternative deformation models (fault slip rates), a new smoothed seismicity algorithm, alternative values for the total rate of M w ≥ 5 events, and different scaling relationships, virtually all of which are new. As a notable first, three deformation models are based on kinematically consistent inversions of geodetic and geologic data, also providing slip-rate constraints on faults previously excluded due to lack of geologic data. The grand inversion constitutes a system-level framework for testing hypotheses and balancing the influence of different experts. For example, we demonstrate serious challenges with the Gutenberg-Richter hypothesis for individual faults. UCERF3 is still an approximation of the system, however, and the range of models is limited (e.g., constrained to stay close to UCERF2). Nevertheless, UCERF3 removes the apparent UCERF2 overprediction of M 6.5-7 earthquake rates and also includes types of multifault ruptures seen in nature. Although UCERF3 fits the data better than UCERF2 overall, there may be areas that warrant further site-specific investigation. Supporting products may be of general interest, and we list key assumptions and avenues for future model improvements. Manuscript OrganizationBecause of manuscript length and model complexity, we begin with an outline of this report to help readers navigate the various sections:

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“…To understand what size of fault can produce a magnitude 3 earthquake, we can use one of the numerous scaling relationships for the magnitude of an earthquake versus the area of slip (e.g., Shaw, 2009;Kanamori, 1977). Using Kanamori (1977), a 250-m (820-ft) radius fault is needed to produce a magnitude 3 earthquake, which would correspond to a circular fault area of ~0.2 km 2 (~0.08 mi 2 ).…”

Section: Discussionmentioning

confidence: 99%

Potential for Induced Seismicity Related to the Northern California CO2 Reduction Project Pilot Test, Solano County, California

Myer¹,

Chiaramonte²,

Daley³

et al. 2010

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Executive SummaryThe objective of this technical report is to analyze the potential for induced seismicity due to a proposed small-scale CO 2 injection project in the Montezuma Hills. We reviewed currently available public information, including 32 years of recorded seismic events, locations of mapped faults, and estimates of the stress state of the region. We also reviewed proprietary geological information acquired by Shell, including seismic reflection imaging in the area, and found that the data and interpretations used by Shell are appropriate and satisfactory for the purpose of this report.The closest known fault to the proposed injection site is the Kirby Hills Fault. It appears to be active, and microearthquakes as large as magnitude 3.7 have been associated with the fault near the site over the past 32 years. Most of these small events occurred 9-17 miles (15-28 km) below the surface, which is deep for this part of California. However, the geographic locations of the many events in the standard seismicity catalog for the area are subject to considerable uncertainty because of the lack of nearby seismic stations; so attributing the recorded earthquakes to motion along any specific fault is also uncertain. Nonetheless, the Kirby Hills Fault is the closest to the proposed injection site and is therefore our primary consideration for evaluating the potential seismic impacts, if any, from injection. Our planned installation of seismic monitoring stations near the site will greatly improve earthquake location accuracy.Shell seismic data also indicate two unnamed faults more than 3 miles east of the project site. These faults do not reach the surface as they are truncated by an unconformity at a depth of about 2,000 feet (610 m). The unconformity is identified as occurring during the Oligocene Epoch, 33.9-23.03 million years ago, which indicates that these faults are not currently active. Farther east are the Rio Vista Fault and Midland Fault at distances of about 6 miles (10 km) and 10 miles (16 km), respectively. These faults have been identified as active during the Quaternary (last 1.6 million years), but without evidence of displacement during the Holocene (the last 11,700 years).* Short biographies of authors are provided in Appendix 1. 1The stress state (both magnitude and direction) in the region is an important parameter in assessing earthquake potential. Although the available information regarding the stress state is limited in the area surrounding the injection well, the azimuth of the mean maximum horizontal stress is estimated at 41° and it is consistent with strike-slip faulting on the Kirby Hills Fault, unnamed fault segments to the south, and the Rio Vista Fault. However, there are large variations (uncertainty) in stress estimates, leading to low confidence in these conclusions regarding which fault segments are optimally oriented for potential slip induced by pressure changes. Uncertainty in the stress state can be substantially reduced by measurements planned when wells are drilled at the s...

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Constant Stress Drop from Small to Great Earthquakes in Magnitude-Area Scaling

Cited by 86 publications

References 19 publications

Coseismic slip in the 2010 Yushu earthquake (China), constrained by wide-swath and strip-map InSAR

Coseismic slip in the 2010 Yushu earthquake (China), constrained by wide-swath and strip-map InSAR

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

Potential for Induced Seismicity Related to the Northern California CO2 Reduction Project Pilot Test, Solano County, California

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