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Dynamic Source Scenarios Constrained by NGA-West2 GMPEs

Session: Physics-Based Earthquake Rupture Modeling and Strong Motion Simulations [Poster]

Type: Poster

Date: 4/22/2021

Presentation Time: 03:45 PM Pacific

Description: 

Dynamic source inversions of individual earthquakes provide constraints on stress and frictional parameters inherent to the studied event (Gallovič et al., 2019). To provide more general properties on how dynamic and kinematic parameters are distributed, we stochastically generate dynamic source models and constrain them by common characteristics extracted from a large number of earthquakes - the ground motion prediction equations (GMPEs). Following Gallovič and Valentová (2020), we employ linear slip-weakening friction law characterized by three parameters (initial stress, characteristic slip-weakening distance, and friction drop) on a vertical strike-slip fault of 36x20km. The rupture propagation is simulated numerically by a finite-difference method implemented in a highly efficient GPU-enabled code FD3D_TSN (Premus et al., 2020), which performs the dynamic calculation in seconds to a minute. The slip rates on the fault resulting from the dynamic simulations are convolved with precalculated Green’s functions (GF) to calculate seismograms with a maximum frequency of 5 Hz for a prescribed set of phantom stations. The models are evaluated by their statistical fit in terms of response spectra (0.5-2 Hz) to adopted NGA-West2 GMPEs of Boore et al. (2014), considering both between-event and within-event variability. The dynamic parameter distributions on the fault are obtained by randomly sampling parameter space employing a Markov chain Monte Carlo approach, namely the parallel tempering method (Sambridge, 2014). The resulting plethora of dynamic scenarios are then treated as a synthetic event database and analyzed to extract dynamic and kinematic parameters, including their variability. The events exhibit various magnitudes in the range of 5.8-6.8 and degrees of complexity (e.g., one or more asperities) and are compatible with scaling relations extracted from the real earthquakes.

Presenting Author: František Gallovic

Student Presenter: No

Authors