Bulletin of the Seismological Society of America; December 2000; v. 90; no. 6;
p. 1498-1506; DOI: 10.1785/0119990163
© 2000 Seismological Society of America
Probability of Rupture of Multiple Fault Segments
D. J. Andrews and
Elizabeth Schwerer
U.S. Geological Survey
345 Middlefield Road, MS 977
Menlo Park, California, 94025
jandrews{at}usgs.gov
Fault segments identified from geologic and historic evidence have
sometimes been adopted as features limiting the likely extends of earthquake
ruptures. There is no doubt that individual segments can sometimes join
together to produce larger earthquakes. This work is a trial of an objective
method to determine the probability of multisegment ruptures. The frequency of
occurrence of events on all conjectured combinations of adjacent segments in
northern California is found by fitting to both geologic slip rates and to an
assumed distribution of event sizes for the region as a whole. Uncertainty in
the shape of the distribution near the maximum magnitude has a large effect on
the solution. Frequencies of individual events cannot be determined, but it is
possible to find a set of frequencies to fit a model closely. A robust
conclusion for the San Francisco Bay region is that large multisegment events
occur on the San Andreas and San Gregorio faults, but single-segment events
predominate on the extended Hayward and Calaveras strands of segments.
Copyright © 2009 by Seismological Society of America