Self-similar slip pulses during rate-and-state earthquake nucleation

TitleSelf-similar slip pulses during rate-and-state earthquake nucleation
Publication TypeJournal Article
Year of Publication2009
AuthorsRubin A.M, Ampuero J-P.
JournalJ. Geophys. Res.
Volume114
IssueB11
Date Published2009/11/01
ISBN Number0148-0227
Keywordsearthquake nucleation, rate- and state-dependent friction
Abstract

For a wide range of conditions, earthquake nucleation zones on rate- and state-dependent faults that obey either of the popular state evolution laws expand as they accelerate. Under the "slip" evolution law, which experiments show to be the more relevant law for nucleation, this expansion takes the form of a unidirectional slip pulse. In numerical simulations these pulses often tend to approach, with varying degrees of robustness, one of a few styles of self-similar behavior. Here we obtain an approximate self-similar solution that accurately describes slip pulses growing into regions initially sliding at steady state. In this solution the length scale over which slip speeds are significant continually decreases, being inversely proportional to the logarithm of the maximum slip speed Vmax, while the total slip remains constant. This slip is close to Dc(1-a/b)-1, where Dc is the characteristic slip scale for state evolution and a and b are the parameters that determine the sensitivity of the frictional strength to changes in slip rate and state. The pulse has a ?distance to instability? as well as a ?time to instability,? with the remaining propagation distance being proportional to (1-a/b)-2 [ln(Vmaxθbg/Dc)]-1, where θbg is the background state into which the pulse propagates. This solution provides a reasonable estimate of the total slip for pulses growing into regions that depart modestly from steady state.

URLhttps://doi.org/10.1029/2009JB006529
DOI10.1029/2009JB006529
Short TitleJournal of Geophysical Research: Solid Earth