Laboratory observations of the response of fault strength as normal stress is changed, and implications for dynamic rupture
Abstract
A pivotal issue for rupture propagation across stepovers and multi-fault intersections is how fault shear resistance depends on normal stress. Rapid normal-stress changes, which should be common at stopovers and intersections, could potentially either aid or inhibit rupture propagation. At present we do not know if shear resistance changes instantaneously with changing normal stress, or if it is insensitive. Therefore, given a particular natural fault geometry, if both shear and normal stresses are important, we cannot accurately assess if earthquakes can rupture fault segment boundaries or jump from fault to fault. New laboratory experiments have been performed, using the methods described in Linker and Dieterich, JGR 1992, to examine the effects that static and transient changes in normal stress have on fault strength. Improved data recording technology and new experimental capabilities permit the careful examination of the response of shear stress, fault closure, and the transmissivity of acoustic signals across a fault, as the magnitude and duration of changes to the applied normal stress on the fault are varied. Preliminary results indicate that fault closure and acoustic transmissivity respond nearly instantaneously to any change in normal stress across the fault. However, the shear stress is consistently slow to respond to changes in the applied normal stress. Consistency of these observations with the existing constitutive relations for friction are examined and comparisons with previously collected laboratory data are presented.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.T21B2167K
- Keywords:
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- 7209 SEISMOLOGY / Earthquake dynamics;
- 8118 TECTONOPHYSICS / Dynamics and mechanics of faulting