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Including foreshocks and aftershocks in time-independent probabilistic seismic hazard analyses

Bulletin of the Seismological Society of America

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DOI: 10.1785/0120110008

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Abstract

Time‐independent probabilistic seismic‐hazard analysis treats each source as being temporally and spatially independent; hence foreshocks and aftershocks, which are both spatially and temporally dependent on the mainshock, are removed from earthquake catalogs. Yet, intuitively, these earthquakes should be considered part of the seismic hazard, capable of producing damaging ground motions. In this study, I consider the mainshock and its dependents as a time‐independent cluster, each cluster being temporally and spatially independent from any other. The cluster has a recurrence time of the mainshock; and, by considering the earthquakes in the cluster as a union of events, dependent events have an opportunity to contribute to seismic ground motions and hazard. Based on the methods of the U.S. Geological Survey for a high‐hazard site, the inclusion of dependent events causes ground motions that are exceeded at probability levels of engineering interest to increase by about 10% but could be as high as 20% if variations in aftershock productivity can be accounted for reliably.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Including foreshocks and aftershocks in time-independent probabilistic seismic hazard analyses
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120110008
Volume
102
Issue:
3
Year Published:
2012
Language:
English
Publisher:
Seismological Society of America
Publisher location:
El Cerrito, CA
Contributing office(s):
Geologic Hazards Science Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
909
Last page:
917