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Geophys. J. Int. (2007) 000, 000000 Cracks, pulses and macroscopic asymmetry of dynamic rupture on a
 

Summary: Geophys. J. Int. (2007) 000, 000­000
Cracks, pulses and macroscopic asymmetry of dynamic rupture on a
bimaterial interface with velocity-weakening friction
J.-P. Ampuero1
and Y. Ben-Zion2
1 Institute of Geophysics, ETH Zšurich, Zšurich, Switzerland. E-mail: ampuero@erdw.ethz.ch
2 Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA.
Accepted xxx. Received xxx; in original form 2007 August 6
SUMMARY
We study in-plane ruptures on a bimaterial fault governed by a velocity-weakening friction with
a regularized normal stress response. Numerical simulations and analytical estimates provide
characterization of the ranges of velocity-weakening scales, nucleation lengths and background
stresses for which ruptures behave as cracks or pulses, decaying or sustained, bilateral or unilat-
eral. With strongly velocity-weakeningfriction, ruptures occur under a wide range of conditions
as large-scale pulses with a preferred propagation direction, that of slip of the more compliant
material. Such ruptures have macroscopic asymmetry manifested by significantly larger seismic
potency and propagation distance in the preferred direction, and clearly quantified by the direc-
tivity ratio derived from the second order moments of the spatio-temporal distribution of slip
rate. The macroscopic rupture asymmetry of the large-scale pulses stems from the difference
in the criticality conditions for self-sustained propagation in each rupture direction, induced by

  

Source: Ampuero, Jean Paul - Division of Geological and Planetary Sciences, California Institute of Technology

 

Collections: Geosciences