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A bilinear source-scaling model for M-log A observations of continental earthquakes

Thomas C. Hanks and William H. Bakun
A bilinear source-scaling model for M-log A observations of continental earthquakes
Bulletin of the Seismological Society of America (June 2002) 92 (5): 1841-1846

Abstract

The Wells and Coppersmith (1994) M-log A data set for continental earthquakes (where M is moment magnitude and A is fault area) and the regression lines derived from it are widely used in seismic hazard analysis for estimating M, given A. Their relations are well determined, whether for the full data set of all mechanism types or for the subset of strike-slip earthquakes. Because the coefficient of the log A term is essentially 1 in both their relations, they are equivalent to constant stress-drop scaling, at least for M< or =7, where most of the data lie. For M>7, however, both relations increasingly underestimate the observations with increasing M. This feature, at least for strike-slip earthquakes, is strongly suggestive of L-model scaling at large M. Using constant stress-drop scaling (Delta sigma = 26.7 bars) for M< or =6.63 and L-model scaling (average fault slip u = alpha L, where L is fault length and alpha = 2.19X10 (super -5) ) at larger M, we obtain the relations M = log A+3.98+ or -0.03, A< or =537 km (super 2) and M = 4/3 log A+3.07+ or -0.04, A>537 km (super 2) . These prediction equations of our bilinear model fit the Wells and Coppersmith (1994) data set well in their respective ranges of validity, the transition magnitude corresponding to A = 537 km (super 2) being M = 6.71


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 92
Serial Issue: 5
Title: A bilinear source-scaling model for M-log A observations of continental earthquakes
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 1841-1846
Published: 200206
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 28
Accession Number: 2002-076545
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200223
Program Name: USGSOPNon-USGS publications with USGS authors
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