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- Title
The Spatiotemporal Evolution of Granular Microslip Precursors to Laboratory Earthquakes.
- Authors
Trugman, Daniel T.; McBrearty, Ian W.; Bolton, David C.; Guyer, Robert A.; Marone, Chris; Johnson, Paul A.
- Abstract
Laboratory earthquake experiments provide important observational constraints for our understanding of earthquake physics. Here we leverage continuous waveform data from a network of piezoceramic sensors to study the spatial and temporal evolution of microslip activity during a shear experiment with synthetic fault gouge. We combine machine learning techniques with ray theoretical seismology to detect, associate, and locate tens of thousands of microslip events within the gouge layer. Microslip activity is concentrated near the center of the system but is highly variable in space and time. While microslip activity rate increases as failure approaches, the spatiotemporal evolution can differ substantially between stick‐slip cycles. These results illustrate that even within a single, well‐constrained laboratory experiment, the dynamics of earthquake nucleation can be highly complex. Plain Language Summary: The fault systems that produce damaging earthquakes are difficult to study directly due to their depth and spatial extent in the Earth's crust. Laboratory earthquake experiments can provide insight into the relevant physical processes active in real earthquake systems. In experiments with granular material that emulates the crushed‐up gouge material of real faults, larger labquakes are always preceded by smaller, foreshock events. In this work, we provide a detailed study of the space‐time evolution of these microslip foreshocks in one such experiment. We show that even in these simplified analogs of real earthquake cycles, earthquake nucleation processes and frictional behavior can vary dramatically from cycle to cycle. In tectonic fault zones on Earth, such complexity will only be magnified. Key Points: We study the spatiotemporal evolution of microslip events in laboratory earthquake experiments with synthetic granular fault gougeWe combine machine learning and conventional seismic processing techniques to develop a catalog of more than 30,000 microslip eventsMicroslip activity increases as failure approaches but exhibits a complex spatiotemporal pattern that varies throughout the experiment
- Subjects
FAULT gouge; EARTHQUAKES; EARTHQUAKE damage; FAULT zones; GRANULAR materials
- Publication
Geophysical Research Letters, 2020, Vol 47, Issue 16, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2020GL088404