SCEC Award Number 23121 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Generation of Near Source Broadband Ground Motion from Physics-based Dynamic Rupture Simulations: Continuing A Group Modeling Approach towards better Characterizing Seismic Hazard for Engineering Applications
Investigator(s)
Name Organization
Kyle Withers United States Geological Survey Luis Dalguer 3Q-Lab (Switzerland) Yongfei Wang University of Southern California Thomas Ulrich Ludwig Maximilian University of Munich (Germany) Alice-Agnes Gabriel University of California, San Diego Benchun Duan Texas A&M University Dunyu Liu University of Texas at Austin Jean-Paul Ampuero California Institute of Technology Domniki Asimaki California Institute of Technology Shuo Ma San Diego State University
Other Participants Yonatan Glehman,
Elif Oral
SCEC Priorities 4a, 1d, 4e SCEC Groups GM, FARM, CS
Report Due Date 03/15/2024 Date Report Submitted 08/23/2024
Project Abstract
 We employ three-dimensional dynamic rupture simulations to generate a database of synthetic, broadband ground motions over a range of earthquake magnitudes, involving a large group of modelers using different numerical approaches and computational implementations. This multi-year effort focuses on the source component that influences ground motions in a one-dimensional layered media, so we constrain our initial comparison to near-source distances, where the effect of anelastic attenuation is minimal. We bin the ground motions from our simulated datasets as a function of period and distance from the fault to evaluate the overall amplitude and trends with empirically-based ground motion models (GMMs). The median and variability of the ground motions from each modeling group are compared both individually and collectively. There is generally good agreement among the synthetic ground motions trends with empirical GMMs at periods shorter than 1 s, with some approaches underestimating spectral amplitudes at the higher frequencies. We separate the total standard deviation into the intra- and inter-event terms, permitting deeper insight into the effects of various ground motion amplification components, such as azimuthal variations in the ground motion. Additionally, we compared dynamic rupture synthetics with observed records from the 2023, Kahramanmaraş, Turkey events, finding that the synthetic ground motions capture shape and amplitude of recorded ground-motion pulses well between 0.01-1Hz, but lack in reproducing variability in pulse orientation. This collection of synthetic ground motions has the potential to be useful for a wide variety of users, for both research and engineering applications.
Intellectual Merit This project focuses on generating earthquake sources that produce synthetic ground motion relevant to engineering applications. This group’s goals fall directly in line with the SCEC5 science objectives, as well as the renewed call to ‘develop methodologies to validate ground motions from dynamic rupture simulations for systematic assessment of aleatory variability and epistemic uncertainty in simulated ground motions.

Our group is a coordinated validation effort to model ground motions from dynamic ruptures. Our research focuses on improving models of earthquake rupture for applications to seismic hazard, utilizing a dynamic rupture approach to validate synthetically generated ground motion, that will both contribute to advancing knowledge in the area of dynamic rupture simulations, as well as understanding how seismic ground motions relate to complex earthquake ruptures.
Broader Impacts This project works towards improving models of earthquake rupture for applications to seismic hazard. This has direct impact to the SCEC research community, especially by potential end users of simulations. The community will benefit from knowing how well the synthetics that result from dynamic rupture simulations compare to observed data or estimates from ground motion prediction equations (GMPEs). The multiple dynamic ruptures approaches used here will ultimately help guide several engineering decisions, such as impacting descriptions of building code and design.

Our group is composed of a broad array of individuals across all stages of career and background, including PhD students and several early-career members, such as postdocs (with representation from several minorities groups as well as international participants).

This project builds a synthetic database of ground motion amplitudes from a diverse range of initial conditions and modeling techniques. Additionally, we also keep track of final fault displacement along the surface trace of the fault. In the future, we intend to make our database publicly available, for use by a variety of other end-users and investigations. For example, it’s likely a few of our simulated events will have similar characteristics to recently recorded events (e.g. the Ridgecrest sequence), that may be used for additional validation and constraint of both surface slip and ground motion amplitudes.
Exemplary Figure Figure 1. Rupture progression, peak slip rate and final slip for a chosen strike-slip event from each group participating in our validation effort.