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Absolute Stress Fields in the Source Region of the 1992 Landers Earthquake

Terakawa, Toshiko and Hauksson, Egill (2018) Absolute Stress Fields in the Source Region of the 1992 Landers Earthquake. Journal of Geophysical Research. Solid Earth, 123 (10). pp. 8874-8890. ISSN 2169-9313. doi:10.1029/2018JB015765.

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Earthquake focal mechanisms are often inverted to obtain the deviatoric stress field. Because shear stress is equal to the frictional strength of the fault at the time of an earthquake, six components of the absolute stress tensor at the hypocenter can be obtained from a focal mechanism by combining deviatoric stress fields with the Coulomb failure criterion. For a data set of focal mechanisms determined for southern California earthquakes, including the 1992 Landers earthquake sequence, we calculated the absolute stress tensors at their hypocenters using a standard intrinsic friction coefficient under three pore pressure conditions, parameterized by the reference pore pressure at the optimally oriented faults to the stress field. Three absolute stress fields were obtained for southern California immediately before the Landers main shock by applying each data set of the stress tensors to an inversion scheme based on Bayesian statistical inference and Akaike's Bayesian Information Criterion. The coseismic stress field was calculated to obtain the absolute stress fields immediately after the main shock. The variations of the coseismic stress rotation were related to the reference pore pressure. Comparing this relation with that obtained through stress inversion, we determined the absolute stress field and the most plausible reference pore pressure to be hydrostatic. On average, the maximum shear stresses immediately before the main shock were 44 ± 15 and 79 ± 24 MPa at depths of 5 and 10 km, respectively. Earthquakes on the off‐plate boundary faults in southern California occur on faults that are loaded by Anderson‐Byerlee stress conditions.

Item Type:Article
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URLURL TypeDescription
Terakawa, Toshiko0000-0003-2460-5306
Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2018 American Geophysical Union. Received 13 MAR 2018; Accepted 22 SEP 2018; Accepted article online 29 SEP 2018; Published online 22 OCT 2018. We are highly grateful to the two anonymous reviewers for their useful suggestions. We would like to thank the Editor Martha Savage. We would like to thank the Southern California Earthquake Data Center (doi:10.7909/C3WD3xH1) for providing focal mechanism solutions in the Southern California Seismic Network catalog (doi:10.7914/SN/CI). This work was supported by a Grant‐in Aid for Scientific Research C (26400451). The data that support the findings of this study are available at‐catalogs/FMsearch.php.
Group:Seismological Laboratory
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)26400451
Subject Keywords:absolute stress fields; pore fluid pressures
Issue or Number:10
Record Number:CaltechAUTHORS:20181127-105102984
Persistent URL:
Official Citation:Terakawa, T., & Hauksson, E. (2018). Absolute stress fields in the source region of the 1992 Landers earthquake. Journal of Geophysical Research: Solid Earth, 123, 8874–8890.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91221
Deposited By: Tony Diaz
Deposited On:27 Nov 2018 21:35
Last Modified:16 Nov 2021 03:39

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