Towards identifying its seismic observables in models of coseismic off-fault damage

Kurama Okubo, Harsha S. Bhat, Esteban Rougier, & Marine A. Denolle

Submitted August 14, 2019, SCEC Contribution #9583, 2019 SCEC Annual Meeting Poster #049

Coseismic off-fault damage is dynamically activated during earthquake ruptures due to stress concentration in the off-fault medium. The contribution of off-fault damage to the radiation and overall energy budget is non-negligible, and thus important to understand the earthquake ruptures on fault systems, especially those with complex geometry. This study investigates the possible seismological observables of the coseismic damage from 2-D dynamic earthquake rupture modeling with dynamic activation of both tensile and shear fractures in the off-fault medium using the combined finite-discrete element method (FDEM). In the case of a planar finite fault, most of the damage occurs around the fault’s edges through substantial generation of secondary fractures. In terms of seismic observables, we first show that the resulting moment-rate function becomes more elongated in time, due to successive slip on the main fault caused by the off-fault damage around the fault’s edges. We couple FDEM to SPECFEM2D to generate far-field seismograms of P, S, and surface waves to identify coseismic off-fault damage in its signature.

Key Words
Dynamic rupture modeling, off-fault damage, FDEM

Okubo, K., Bhat, H. S., Rougier, E., & Denolle, M. A. (2019, 08). Towards identifying its seismic observables in models of coseismic off-fault damage. Poster Presentation at 2019 SCEC Annual Meeting.

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