Geological Society of America

T36 Induced and Triggered Earthquakes in the United States and Canada

Monday, 26 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

3D FAULT ARCHITECTURE CONTROLS THE DYNAMISM OF EARTHQUAKE SWARMS

Paper number: T36-3
Program: Technical Sessions
Time: 5:50 PM – 6:05 PM

Authors

Zachary E. Ross Presenting Author
California Institute of Technology, Pasadena, CA
Elizabeth S. Cochran
U.S. Geological Survey, Pasadena, CA
Daniel T. Trugman
The University of Texas at Austin, Austin, TX
Jonathan D. Smith
California Institute of Technology, Pasadena, CA

Abstract

The vibrant evolutionary patterns made by earthquake swarms are incompatible with standard, effectively two-dimensional (2D) models for general fault architecture. We leverage advances in earthquake monitoring with a deep-learning algorithm to image a fault zone hosting a 4-year-long swarm in southern California. We infer that fluids are naturally injected into the fault zone from below and diffuse through strike-parallel channels while triggering earthquakes. A permeability barrier initially limits up-dip swarm migration but ultimately is circumvented. This enables fluid migration within a shallower section of the fault with fundamentally different mechanical properties. Our observations provide high-resolution constraints on the processes by which swarms initiate, grow, and arrest. These findings illustrate how swarm evolution is strongly controlled by 3D variations in fault architecture.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-349714

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