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Fault friction, regional stress, and crust-mantle coupling in southern California from finite element modelsTo determine the correct fault rheology of the Transverse Ranges area of California, a new finite element to represent faults and a mangle drag element are introduced into a set of 63 simulation models of anelastic crustal strain. It is shown that a slip rate weakening rheology for faults is not valid in California. Assuming that mantle drag effects on the crust's base are minimal, the optimal coefficient of friction in the seismogenic portion of the fault zones is 0.4-0.6 (less than Byerly's law assumed to apply elsewhere). Depending on how the southern California upper mantle seismic velocity anomaly is interpreted, model results are improved or degraded. It is found that the location of the mantle plate boundary is the most important secondary parameter, and that the best model is either a low-stress model (fault friction = 0.3) or a high-stress model (fault friction = 0.85), each of which has strong mantel drag. It is concluded that at least the fastest moving faults in southern California have a low friction coefficient (approximtely 0.3) because they contain low strength hydrated clay gouges throughout the low-temperature seismogenic zone.
Document ID
19840045113
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bird, P.
(California Univ. Los Angeles, CA, United States)
Baumgardner, J.
(California, University Los Angeles, CA, United States)
Date Acquired
August 12, 2013
Publication Date
March 10, 1984
Publication Information
Publication: Journal of Geophysical Research
Volume: 89
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
84A27900
Funding Number(s)
CONTRACT_GRANT: USGS-14-08-0001-19142
CONTRACT_GRANT: NAS5-26957
Distribution Limits
Public
Copyright
Other

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