Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 1998 | Published
Journal Article Open

The static stress change triggering model: Constraints from two southern California aftershock sequences

Abstract

Static stress change has been proposed as a mechanism of earthquake triggering. We quantitatively evaluate this model for the apparent triggering of aftershocks by the 1992 M_W 7.3 Landers and 1994 M_W 6.7 Northridge earthquakes. Specifically, we test whether the fraction of aftershocks consistent with static stress change triggering is greater than the fraction of random events which would appear consistent by chance. Although static stress changes appear useful in explaining the triggering of some aftershocks, the model's capability to explain aftershock occurrence varies significantly between sequences. The model works well for Landers aftershocks. Approximately 85% of events between 5 and 75 km distance from the mainshock fault plane are consistent with static stress change triggering, compared to ∼50% of random events. The minimum distance is probably controlled by limitations of the modeling, while the maximum distance may be because static stress changes of <0.01 MPa trigger too few events to be detected. The static stress change triggering model, however, can not explain the first month of the Northridge aftershock sequence significantly better than it explains a set of random events. The difference between the Landers and Northridge sequences may result from differences in fault strength, with static stress changes being a more significant fraction of the failure stress of weak Landers-area faults. Tectonic regime, regional stress levels, and fault strength may need to be incorporated into the static stress change triggering model before it can be used reliably for seismic hazard assessment.

Additional Information

© 1998 American Geophysical Union. Manuscript Accepted: 10 February 1998; Manuscript Received: 2 July 1997. We thank Emily Brodsky, Andrew Michael, Joan Gomberg and an anonymous reviewer for their useful comments on the manuscript. We thank David Wald for providing us with his main shock slip models and Robert Simpson for the use of his program ELFPOINT. This work was partially supported by USGS grant 1434-HQ-97-GR-03028 and partially supported by the Southern California Earthquake Center (SCEC) which is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. SCEC contribution 370. Contribution 5813, Caltech Division of Geological and Planetary Sciences.

Attached Files

Published - jgrb11428.pdf

Files

jgrb11428.pdf
Files (1.2 MB)
Name Size Download all
md5:106901cc781a0dab164c4d73633289a0
1.2 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023