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Kinematic Rupture Generator Based on 3D Rough Fault Dynamic Rupture Simulations

William H. Savran, Kim B. Olsen, & Steven M. Day

Published April 20, 2017, SCEC Contribution #7278

Spontaneous rupture simulations using geometrically-rough faults have been shown to produce realistic far-field spectra and comparable fits with GMPEs, but they are too computationally demanding for use with physics-based probabilistic seismic hazard analysis efforts such as the Southern California Earthquake Center CyberShake or Broadband Platforms. Here, we present our implementation of a kinematic rupture generator that mimics (at least in a statistical sense) the processes of rough-fault spontaneous rupture models that are responsible for generating realistic broadband sources. 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 inter-plate strike-slip events, and provide source spectra comparable with an ω-2 source model. To define our kinematic source model, we use an exponential source-time function parameterized in terms of slip, peak slip velocity, and rupture velocity. These parameters are represented by random fields whose distributional parameters are estimated from the dynamic ensembles. Our method uses sequential Gaussian co-simulation to generate the random spatial fields using two-point statistics defined by a linear model of coregionalization. We incorporate a nested-model of linearly independent variogram basis functions to capture correlations at all scale lengths between all source parameters and the initial friction on the fault. Additionally, we introduce the variability observed in one-point statistics by defining a multivariate Gaussian random variable model. Finally, we show that ground motions calculated by the kinematic model have amplitudes and spectral content comparable with those of the dynamic rupture simulations.

Savran, W. H., Olsen, K. B., & Day, S. M. (2017, 04). Kinematic Rupture Generator Based on 3D Rough Fault Dynamic Rupture Simulations. Poster Presentation at Seismological Society of America.

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