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Published July 2017 | Published + Accepted Version
Book Section - Chapter Open

Upper limit on damage zone thickness controlled by seismogenic depth

Abstract

The thickness of fault damage zones, a characteristic length of the cross‐fault distribution of secondary fractures, significantly affects fault stress, earthquake rupture, ground motions, and crustal fluid transport. Field observations indicate that damage zone thickness scales with accumulated fault displacement at short displacements but saturates at a few hundred meters for displacements larger than a few kilometers. To explain this transition of scaling behavior, we conduct 3D numerical simulations of dynamic rupture with off‐fault inelastic deformation on long strike‐slip faults. We find that the distribution of coseismic inelastic strain is controlled by the transition from crack‐like to pulse‐like rupture propagation associated with saturation of the seismogenic depth. The yielding zone reaches its maximum thickness when the rupture becomes a stable pulse‐like rupture. Considering fracture mechanics theory, we show that seismogenic depth controls the upper bound of damage zone thickness on mature faults by limiting the efficiency of stress concentration near earthquake rupture fronts. We obtain a quantitative relation between limiting damage zone thickness, background stress, dynamic fault strength, off‐fault yield strength, and seismogenic depth, which agrees with first‐order field observations. Our results help link dynamic rupture processes with field observations and contribute to a fundamental understanding of damage zone properties.

Additional Information

© 2017 American Geophysical Union. Published 2017 by John Wiley & Sons, Inc. Published Online: 19 June 2017; Published Print: 30 June 2017. This work was supported by the Southern California Earthquake Center (Contribution No. 7202. SCEC is funded by NSF Cooperative Agreement EAR‐1033462 and USGS Cooperative Agreement G12AC20038) and by the National Science Foundation (CAREER award EAR‐1151926). We thank Yoshihiro Kaneko for sharing his version of the SPECFEM3D code modified for the SCEC TPV27 benchmark, and Steve Day and an anonymous reviewer for their stimulating comments.

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Published - 9781119156895.ch13.pdf

Accepted Version - Ampuero_Mao_2016.pdf

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Created:
August 21, 2023
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