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Yielding and Fracture in the Nucleation of Frictional Fault Slip

Description: 

Although friction is reduced in textbooks to a simple friction coefficient, reality is much more complex than it seems. The transition from static to dynamic friction that lies behind seismic activity happens through a nucleation process involving the yielding and fracture of contact asperities along natural faults. However, little is known as to what the dominant underlying process is or what the implications are for nucleation dynamics and the onset of frictional instability. In this work, we show that fault heterogeneity, modeled through the correlation length and the amplitude of frictional strength, plays a key role in determining the driving force behind the nucleation of slip. In particular, we found that a transition from yielding to fracture is triggered above a certain level of heterogeneity, which is responsible for the generation of foreshock events, and that the magnitude of such events increases with the correlation length and decreases with the amplitude of the frictional strength profile. Moreover, high levels of heterogeneity are shown to favor stability and delay the onset of dynamic friction. Overall, our results demonstrate how fault heterogeneity influences the nucleation of frictional slip by determining whether yielding or fracture dominate the process. This bridges the gap between the two most common criteria for nucleation, which apply only to the yielding or the fracture phase, exclusively.

Session: Earthquake Source Parameters: Theory, Observations and Interpretations

Type: Oral

Date: 4/18/2023

Presentation Time: 10:45 AM (local time)

Presenting Author: Miguel Castellano

Student Presenter: Yes

Invited Presentation: 

Authors