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A 2D Pseudodynamic Rupture Model Generator for Earthquakes on Geometrically Complex Faults

Daniel T. Trugman, & Eric M. Dunham

Published February 2014, SCEC Contribution #1763

Realistic simulations of strong ground motion in future scenario earthquakes are essential to the assessment of seismic hazard. Most earthquake simulations assume piecewise planar fault geometry. However, geologic observations indicate that real faults are fractally rough surfaces, with deviations from planarity at all length scales. Earthquake rupture simulations on nonplanar faults demonstrate that earthquake source parameters, such as slip distribution and rupture velocity, strongly depend on the local fault geometry. In this study, we analyze ensembles of two-dimensional plane strain rupture simulations on fractally rough faults with rate-weakening friction and off-fault viscoplasticity. We observe strong anti-correlation of the magnitude of the final slip distribution, rupture velocity, and peak slip velocity with the local fault slope for right-lateral strike-slip ruptures. The heterogeneity in these earthquake source parameters excites high-frequency seismic waves that are consistent with observed strong motion records. While accurate modeling of this high-frequency motion is critical to seismic hazard analysis, dynamic rupture simulations are currently too computationally inefficient to be of practical use in such applications. We therefore develop a hybrid kinematic-dynamic, or “pseudo-dynamic,” model that incorporates the source parameter correlations observed in fully dynamic rupture simulations, while retaining the computational efficiency of kinematic source modeling. We find that the seismic waves excited by the pseudo-dynamic model have similar intensity and spectral content to the analogous dynamic model, allowing for the model’s future application in efficient earthquake simulations that accurately quantify high-frequency ground motion.

Trugman, D. T., & Dunham, E. M. (2014). A 2D Pseudodynamic Rupture Model Generator for Earthquakes on Geometrically Complex Faults. Bulletin of the Seismological Society of America, 104(1), 95-112. doi: 10.1785/0120130138.

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Computational Science