Kinematic rupture generator based on 3D spontaneous rupture simulations along geometrically rough faults

William H. Savran, & Kim B. Olsen

In Preparation April 30, 2020, SCEC Contribution #10083

Spontaneous rupture simulations along geometrically-rough faults have been shown to produce realistic far-field spectra and comparable fits with ground motion metrics such as spectral accelerations and peak motions from Ground Motion Prediction Equations (GMPEs), but they are too computationally demanding for use with physics-based probabilistic seismic hazard analysis efforts. Here, we present our implementation of a kinematic rupture generator that matches the statistical characteristics of, at least in a statistical sense, rough-fault spontaneous rupture models. To this end, we analyze ~100 dynamic rupture simulations on strike-slip faults ranging from Mw 6.4 - 7.2. We find that our dynamic simulations follow empirical scaling relationships for strike-slip events, and provide source spectra comparable to a source model with ω^(-2) decay. To define our kinematic source model, we use a regularized Yoffe function parameterized in terms of slip, peak-time, rise-time, and rupture initiation time. These parameters are defined through empirical relationships with random fields whose one- and two-point statistics are derived from the dynamic rupture simulations. Our rupture generator reproduces Next Generation Attenuation (NGA) West2 GMPE medians and intra-event standard deviations of spectral accelerations with periods as short as 0.2s for ensembles of ground motion simulations. Our rupture generator produces kinematic source models for M6.4 - 7.2 strike-slip scenarios that can be used in broadband physics-based probabilistic seismic hazard efforts or to supplement data in areas of limited observations for the development of future GMPEs.

Citation
Savran, W. H., & Olsen, K. B. (2020). Kinematic rupture generator based on 3D spontaneous rupture simulations along geometrically rough faults. Journal of Geophysical Research, (in preparation).