Toward a time-dependent probabilistic seismic hazard analysis for Alaska

By: , and 
Edited by: Jeffery T. FreymuellerPeter J. HaeusslerRobert L. Wesson, and Goran Ekstrom

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Abstract

We report on a time-dependent seismic hazard analysis for Alaska and the Aleutians to complement our recently completed time-independent map. Whereas the time-independent map treats all sources as statistically independent, the time-dependent analysis is based on calculations of the conditional probability of occurrence for the next 50 years by using a Brownian Passage Time model for the seismic sources judged to be characteristic. We then consider how those probabilities are modified by coseismic and postseismic stress changes resulting from large regional earthquakes occurring from 1938 to 2002. Recombining the time-dependent probabilities with time-independent truncated Gutenberg–Richter and smoothed seismicity sources leads to our time-dependent probabilistic seismic hazard results. We find that when accounting for time dependence without stress changes, earthquake probabilities can be significantly altered, reducing probabilities to near zero or increasing them to several times the time-independent values. In addition, accounting for coseismic stress changes tends to have a local influence on earthquake probabilities, whereas postseismic effects can be far-reaching in both time and space. In sum, however, since we combine time-dependent and time-independent sources, the modification to seismic hazard is relatively minor, increasing or decreasing hazard adjacent to characteristic faults by about 10%. Most cities, located far from characteristic faults, are little affected.

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Publication type Book chapter
Publication Subtype Book Chapter
Title Toward a time-dependent probabilistic seismic hazard analysis for Alaska
DOI 10.1029/179GM23
Volume 179
Year Published 2008
Language English
Publisher American Geophysical Union
Contributing office(s) Earthquake Science Center, Geologic Hazards Science Center
Description 18 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Active tectonics and seismic potential of Alaska
First page 399
Last page 416
Country United States
State Alaska
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