Applying Earthquake Stress Triggering Models to Seismic Hazard Assessment

by Jeanne Hardebeck
SIO IGPP Green Scholar
University of California, San Diego

3-4pm
Friday January 24, 2003
Refreshments served at 2:45pm
Munk Conference Room
Cecil and Ida M. Green Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California, San Diego
http://mahi.ucsd.edu/seminar/

Abstract

Stress triggering concepts are beginning to be used in quantitative
estimates of earthquake probability.  Given the potentially large
uncertainties in these calculations, it is unclear whether the resulting
small probability changes are significant and meaningful for the purposes
of seismic hazard assessment.  I present a case study of the effect of
the 1992 M7.3 Landers, California, earthquake on the probability of a
major earthquake on the San Andreas Fault in southern California.  It is
a large event in a well-studied region, so this scenario should have a
relatively large signal and low uncertainty. I find that the earthquake
probability change is not significant with respect to the uncertainty in
the earthquake probability.  This example, comparisons with other studies,
and exploration of parameter space imply that the probability changes
due to stress triggering are significant only for time intervals which
are short compared to the repeat time of the target fault.  Therefore,
stress change calculations will be useful in long-term seismic hazard
assessment only for low slip-rate faults.  Otherwise, stress triggering
calculations are best utilized in the short-term immediately following
a major earthquake.