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

Rubin, Allan M. and Ampuero, Jean-Paul (2009) Self-similar slip pulses during rate-and-state earthquake nucleation. Journal of Geophysical Research B, 114 (B11). Art. No. B11305. ISSN 0148-0227.

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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 V_(max), while the total slip remains constant. This slip is close to D_c(1−a/b)^(−1), where D_c 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(V_(max)Θ_(bg)/D_c)]^(−1), where Θ_(bg) 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.

Item Type:Article
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Ampuero, Jean-Paul0000-0002-4827-7987
Additional Information:© 2009 American Geophysical Union. Received 9 April 2009; accepted 22 July 2009; published 5 November 2009. This research was supported by NSF grant EAR-0538156. We thank an anonymous reviewer and the Associate Editor for detailed comments that helped clarify many aspects of the manuscript.
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:rate- and state-dependent friction; earthquake nucleation
Issue or Number:B11
Record Number:CaltechAUTHORS:20091123-141937878
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Official Citation:Rubin, A. M., and J.-P. Ampuero (2009), Self-similar slip pulses during rate-and-state earthquake nucleation, J. Geophys. Res., 114, B11305, doi:10.1029/2009JB006529.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16786
Deposited By: Jason Perez
Deposited On:24 Nov 2009 17:58
Last Modified:03 Oct 2019 01:17

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