Energy budget of dynamic shear ruptures: connecting remote observations with local physical behavior

Valere R. Lambert, & Nadia Lapusta

Published June 20, 2019, SCEC Contribution #10090

Many studies of dynamic shear ruptures seek to shed light on local physical behavior using averaged quantities from remote observations, such as static stress drop, (averaged) breakdown energy and radiation efficiency in seismology. These inferences rely on the use of idealized rupture models, whereas the actual spatial distribution of slip and local stress change may vary substantially throughout the ruptured area. The relationship between observationally-inferred average rupture characteristics, such as breakdown energy and radiation efficiency, and their actual values is therefore not directly evident. We explore this relationship using fully dynamic simulations of sequences of seismic and aseismic slip incorporating Dieterich-Ruina rate-and-state friction as well as enhanced dynamic weakening.

We find that simulations that produce crack-like ruptures result in averaged rupture behavior that is agreeable with standard energy considerations inspired by fracture mechanics, within a relatively modest error of a factor of 2. In contrast, the standard energy budget does not apply to simulations that result in self-healing pulse-like ruptures, which are characterized by substantial stress undershoot, resulting in a significant discrepancy between the average dynamic and static stress changes. We will report on our results investigating the differences between pulse-like ruptures due to self-healing frictional resistance versus geometric constraints.

Citation
Lambert, V. R., & Lapusta, N. (2019, 06). Energy budget of dynamic shear ruptures: connecting remote observations with local physical behavior. Poster Presentation at Engineering Mechanics Institute.