SCEC Award Number 24089 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Developing Efficient Dynamic Simulations of Sequences of Earthquakes and Aseismic Slip for Dipping Fault Geometries
Investigator(s)
Name Organization
Valere Lambert University of California, Santa Cruz
SCEC Milestones C1,2,3-1, D1-1, C2-2 SCEC Groups FARM, SDOT, RC
Report Due Date 03/15/2025 Date Report Submitted 03/27/2025
Project Abstract
 Understanding the evolution of fault conditions, such as fault stress, over periods of slow and fast motion is crucial for assessing how dynamic earthquake ruptures start, grow, and stop and developing physics-based predictive models of plausible future rupture scenarios. Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) are well-suited to explore such problems as they aim to capture how the history of previous earthquakes and aseismic processes modify fault stress and other conditions that influence the nucleation and rupture processes of future dynamic events. There is growing interest in developing simulations of earthquake source processes in fault models with varying degrees of non-planarity as well as non-vertical dipping faults. Examining the influence of fault geometry and inertial effects, as well as their numerical implementation, in models of long-term fault behavior is a priority of the SCEC-supported SEAS code-verification project, which has recently extended benchmark exercises to 2D quasi-dynamic problems including 1-D dipping fault geometries and vertical fault models with full elastodynamics. The results of these exercises highlight the individual importance of considering full elastodynamics and nonvertical dip angles in SEAS models, as both influence short- and long-term earthquake behavior and are relevant to seismic hazard. Examining the combined effects of these ingredients in the context of earthquake sequences is a target for the next generation of SEAS benchmark exercises. We have been developing an efficient boundary element method with the goal of performing SEAS simulations in fault models with dipping fault geometries and full inertial effects.
Intellectual Merit Examining the influence of fault geometry and inertial effects, and their numerical implementation, in models of long-term fault behavior is a priority of the SCEC-supported SEAS code-verification project, which has recently extended benchmark exercises to 2D quasi-dynamic problems including dipping fault geometries and vertical fault models with full elastodynamics. The results of these exercises highlight the individual importance of full elastodynamics and nonvertical dip angles in SEAS models, as both influence short- and long-term earthquake behavior and are relevant to seismic hazards. Examining the combined effects of these ingredients is a target for the next generation of SEAS benchmark exercises.
Broader Impacts The simulation code QDBIM developed in support by this project has contributed to the design of benchmark problems for the SEAS code-verification initiative, which aims to advance computational capabilities and best practices in physics-based computational modeling of fault processes. This project has also contributed to the training of the next generation of computational geoscientists by engaging a graduate student in developing and performing computational simulations of earthquake and faulting processes.
Project Participants Valère Lambert (Principal Investigator), Minghan Yang (graduate student at University of California, Santa Cruz)
Exemplary Figure Figure 2. Evolution of fault slip and inter-event times for sequences of earthquakes and aseismic slip on normal faults with varying fault dips. Left) The evolution of seismic slip (red) is shown during simulated earthquakes (contoured every second) with contours of aseismic slip (blue) shown every 10 years for fault dips of A) 90, B) 60, and C) 30 degrees. To the right of the slip histories for each fault geometry are the interevent times between seismic events (top) and the coseismic slip accumulated at the surface (z = 0) during each event (bottom).
Linked Publications

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