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Crustal stress field in southern California and its implications for fault mechanics

Hardebeck, Jeanne L. and Hauksson, Egill (2001) Crustal stress field in southern California and its implications for fault mechanics. Journal of Geophysical Research B, 106 (B10). pp. 21859-21882. ISSN 0148-0227. doi:10.1029/2001JB000292.

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We present a new, high spatial resolution image of stress orientation in southern California based on the inversion of earthquake focal mechanisms. We use this image to study the mechanics of faulting in the plate boundary region. The stress field contains significant spatial heterogeneity, which in some cases appears to be a result of the complexity of faulting and in other cases appears to be a cause. Temporal changes in the stress field are also observed, primarily related to major earthquakes. The observed 15° (±10°) rotation of the stress axes due to the 1992 M7.3 Landers mainshock implies that the deviatoric stress magnitude in the crust is low, of the order of 10 MPa. This suggests that active faults in southern California are weak. The maximum principal stress axis near the San Andreas Fault is often at ∼50° to the fault strike, indicating that the shear stress on the fault is comparable to the deviatoric stress. The San Andreas in southern California may therefore be a weak fault in a low-strength crust.

Item Type:Article
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Hauksson, Egill0000-0002-6834-5051
Additional Information:© 2001 American Geophysical Union. Manuscript Accepted: 4 April 2001; Manuscript Received: 28 September 2000. We thank Andy Michael for providing us with his stress inversion code and for valuable discussions about stress inversion techniques. John Townend and Yukinobi Sugihara kindly shared their stress inversion results. The manuscript was greatly improved by constructive comments from Craig Nicholson and an anonymous reviewer. This work was partially supported by U.S. Geological Survey grant 01HQGR0038 and partially supported by the Southern California Earthquake Center (SCEC), which is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. SCEC contribution 541. Contribution 8720, Caltech Division of Geological and Planetary Sciences.
Group:Seismological Laboratory
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)541
Caltech Division of Geological and Planetary Sciences8720
Issue or Number:B10
Record Number:CaltechAUTHORS:20130514-103234284
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Official Citation:Hardebeck, J. L., and E. Hauksson (2001), Crustal stress field in southern California and its implications for fault mechanics, J. Geophys. Res., 106(B10), 21859–21882, doi:10.1029/2001JB000292.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38489
Deposited On:14 May 2013 20:48
Last Modified:09 Nov 2021 23:37

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