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Generation of Broadband Ground Motion From Dynamic Rupture Simulations: A Group Modeling Approach Towards Better Characterizing Seismic Hazard for Engineering Applications

Session: Physics-Based Earthquake Rupture Modeling and Strong Motion Simulations II

Type: Oral

Date: 4/23/2021

Presentation Time: 02:00 PM Pacific

Description: 

We present updated results from a recently formed SCEC-led project that focuses on a collaborative approach to validate ground motions produced from dynamic rupture simulations. We use physics-informed simulations to generate deterministic broadband ground motions; the synthetic median and variability of our simulations are compared with recently developed ground motion models (GMMs). By performing this verification and validation, our goal is to address relevant needs of the seismic hazard modelling community.

For source-to-site geometries with limited ground motion records, simulations provide an approach to constrain ground motion amplitudes and trends. We work toward improving methods for simulating earthquake ground motions for seismic hazard applications via a group modeling effort that incorporates features of the earthquake fault and rupture that have been demonstrated from both observations and numerical simulations to affect resulting ground motions. Each of the half dozen model groups generates suites of simulations using their preferred code and dynamic rupture method, creating a diverse distribution of rupture behavior and sampling epistemic uncertainty. For example, two end-member cases include: 1) a uniform regional stress field projected onto a rough-fault profile, and 2) superimposed stress heterogeneity along a planar fault. We focus on the magnitude (Mw) range of ~5 to 7 at distances up to 20 km from the source, comparing median spectral accelerations across a range of periods. We compare our synthetically generated ground motion with four GMMs. Additionally, we analyze synthetic ground motion variability (which can be isolated in terms of both within- and between-event terms) as a function of both distance and period. The aggregated level of ground motion compares well with GMMs’ predictions, and the within-event variability is highly dependent on hypocenter location, resulting from azimuthal changes in ground motion amplification.

Presenting Author: Kyle B. Withers

Student Presenter: No

Authors