SCEC Award Number 21065 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Advancing Simulations of Sequences of Earthquakes and Aseismic Slip (SEAS)
Investigator(s)
Name Organization
Brittany Erickson University of Oregon Junle Jiang University of Oklahoma Michael Barall United States Geological Survey
Other Participants We expect about 20 students and 10 PIs who will be participating in this work.
SCEC Priorities 1d, 1e, 3f SCEC Groups SDOT, FARM, CS
Report Due Date 03/15/2022 Date Report Submitted 03/20/2022
Project Abstract
 Developing robust predictive models of earthquake source processes is one of the main SCEC goals. Research groups within the earthquake science community are contributing to this goal through the development of computational methods for simulating Sequences of Earthquakes and Aseismic Slip (SEAS). In SEAS models, the goal is to capture the interplay of interseismic periods and the associated aseismic fault slip—that ultimately lead to earthquake nucleation—and earthquakes (dynamic rupture events) themselves, and understand which physical factors control the full range of observables such as aseismic deformation, earthquake nucleation, ground shaking during dynamic rupture, recurrence times and magnitudes of major earthquakes. One of the significant challenges in SEAS modeling efforts arises from the varying temporal and spatial scales that characterize earthquake source behavior. Computations are further complicated when material heterogeneities, bulk inelastic responses, fault nonplanarity, and their evolution with time and slip, are included. However, accounting for such complexity is widely recognized as crucial for understanding the real Earth and predicting seismic hazards.
Intellectual Merit SCEC has supported community code exercises on verifying and validating spontaneous dynamic earthquake rupture simulations [Harris et al., 2009; Barall and Harris, 2015; Harris et al., 2018] and comparing Earthquake Simulators [Dieterich and Richards-Dinger, 2010; Tullis et al., 2012]. Dynamic rupture simulations have allowed us to investigate the underlying physics of what influences ground motion, but they are limited to single-event scenarios with imposed artificial prestress conditions and ad hoc nucleation procedures. In contrast, Earthquake Simulators can produce long-term earthquake sequences but often adopt semi-kinematic assumptions and are missing key physical features that could potentially dominate earthquake and fault interaction, such as stress transfer generated by dynamic waves, aseismic slip within fault segments, and inelastic responses. A new generation of numerical SEAS models are thus needed to simulate longer periods of earthquake activity than single-event simulations but with the same level of computational rigor, while incorporating physical factors important over longer time scales. These verified SEAS models would better inform initial conditions and nucleation procedures for dynamic rupture simulations and provide physics-based approximations for larger-scale, longer-term earthquake simulators. The results and lessons from the recent benchmarks prepare us for the next benchmark problems in which we plan to incrementally incorporate additional physical factors, including fluid effects, alternative friction laws, and increased complexity in the fault geometry and bulk material response, particularly in 3D problems, which should advance the state-of-the-art computational capabilities in our field.
Broader Impacts The SEAS initiative has grown in its fourth year at SCEC, with strides in community building, developing new code verification benchmarks, organizing workshops, and promoting visibility of SEAS modeling in the SCEC community and beyond. For all our code verification efforts, the workshops have proven to be particularly valuable in providing an ideal platform for all modelers to share and follow recent scientific progress in the field, discuss details in benchmark design/results, and collectively decide the directions of our future efforts, with considerable inputs from students and early career scientists.
Exemplary Figure Figure 1.