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Subsonic and intersonic shear rupture of weak planes with a velocity weakening cohesive zone

Samudrala, O. and Huang, Y. and Rosakis, A. J. (2002) Subsonic and intersonic shear rupture of weak planes with a velocity weakening cohesive zone. Journal of Geophysical Research B, 107 (B8). Art. No. 2170. ISSN 0148-0227. doi:10.1029/2001JB000460.

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A substantial effort has been devoted in the past toward modeling earthquake source mechanisms as dynamically extending shear cracks. Most of the attention was focused on the subsonic crack speed regime. Recently, a number of reports have appeared in the seismological literature citing evidence of intersonic rupture speeds during shallow crustal earthquakes. In the first part of this paper, we discuss direct experimental observations of intersonic in-plane shear crack growth along a weak plane joining two homogeneous, isotropic, linear elastic plates. Associated with the primary intersonic crack and at locations behind the propagating shear crack tip, a series of secondary tensile cracks, at a steep angle to the shear crack plane, were also observed. Motivated by these observations, subsonic and intersonic mode II crack propagation with a velocity weakening cohesive zone is analyzed in the main body of the paper. A cohesive law is assumed wherein the cohesive shear traction is either a constant or decreases linearly with the local slip rate, the rate of decrease governed by a slip rate weakening parameter. The cohesive shear traction is assumed to vanish when the crack tip sliding displacement reaches a characteristic breakdown slip. It is shown that a positive energy flux into the rupture front is possible in the entire intersonic regime. The influence of shear strength and of the weakening parameter on the crack propagation behavior is investigated. Crack tip stability issues are also addressed, and favorable speed regimes are identified. Estimates of the slip rate weakening parameter are obtained by using the theoretical model to predict the angle of the secondary cracks. The rest of the parameters are subsequently estimated by comparing the isochromatic fringe patterns (contours of maximum in-plane shear stress) predicted by the solution with those recorded experimentally.

Item Type:Article
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URLURL TypeDescription
Rosakis, A. J.0000-0003-0559-0794
Additional Information:Copyright 2002 by the American Geophysical Union. Received 13 February 2001; revised 9 July 2001; accepted 14 July 2001; published 23 August 2002. The authors gratefully acknowledge the support of the National Science Foundation (grants CMS9813100 and CMS9983779) and of the Office of Naval Research (grants N00014-95-1-0453 and N00014-01-1-0204, Y. D. S. Rajapakse, Project Monitor). Many helpful discussions with J. R. Rice of Harvard University and A. Needleman of Brown University are also acknowledged.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-95-1-0453
Office of Naval Research (ONR)N00014-01-1-0204
Subject Keywords:intersonic, shear rupture, weak planes, fault mechanics
Issue or Number:B8
Classification Code:7209 Seismology: Earthquake dynamics and mechanics; 7260 Seismology: Theory and modeling; 8010 Structural Geology: Fractures and faults
Record Number:CaltechAUTHORS:20141027-104113705
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Official Citation:Samudrala, O., Y. Huang, and A. J. Rosakis, Subsonic and intersonic shear rupture of weak planes with a velocity weakening cohesive zone, J. Geophys. Res., 107(B8), doi:10.1029/2001JB000460, 2002
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50843
Deposited By: George Porter
Deposited On:27 Oct 2014 17:58
Last Modified:10 Nov 2021 19:01

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