Uncertain stress calculation apply to aftershock distribution
Speaker: I-Ming, Tai
Abstract
It is known that the coulomb stress drop on a fault plane due to the occurrence of an earthquake. In other works, aftershocks triggering by Coulomb stress changes. The areas which aftershocks occur are usually related to the positive coulomb stress changing zone, but the aftershocks also occur
on the shadow zone in some cases. In this study, they relate stress changes to earthquake rates using the framework of rate-and-state friction which properly takes into consideration the rate and slip dependence of frictional strength and time-dependent restrengthening observed in laboratory
experiments. To compute coseismic stress perturbations on the seismicity rate changes forecasted through a rate- and state-dependent frictional model. The model is implemented using solutions for nucleation of unstable fault slip on faults with experimentally derived rate-and-state dependent fault properties. They use the aftershock activity following the 1992 M7.3 Landers (California) earthquake as a case study. To accomplish these tasks, they first analyze the variability of stress changes resulting from the use of different published slip distributions. They find that the standard deviation of the uncertainty is of the same size as the absolute stress change and that their ratio, the coefficient of variation (CV), is approximately constant in space. Finally, they measure a friction parameter Aσn ? 0.017 MPa and a coefficient of stress variation CV = 0.95.
Reference
Dieterich, J. H. (1994), A constitutive law for rate of earthquake production and its application to earthquake clustering, J.Geophys. Res., 99(B2), 2601–2618.
Hainzl,S., Enescu,B., Cocco,M., Catalli,F., Wang,R., and Roth,F. (2009), Aftershock modeling based on uncertain stress calculations, J.Geophys. Res., VOL. 114, B05309, doi:10.1029/2008JB006011.