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3D fault architecture controls the dynamism of earthquake swarms

Journal Article · · Science
 [1];  [2];  [3];  [1]
  1. California Institute of Technology (CalTech), Pasadena, CA (United States)
  2. US Geological Survey, Pasadena, CA (United States)
  3. Univ. of Texas, Austin, TX (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

The vibrant evolutionary patterns made by earthquake swarms are incompatible with standard, effectively two-dimensional (2D) models for general fault architecture. Here 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.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Laboratory Directed Research and Development (LDRD) Program; Southern California Earthquake Center
Grant/Contract Number:
89233218CNA000001
OSTI ID:
1739984
Report Number(s):
LA-UR--20-20957
Journal Information:
Science, Journal Name: Science Journal Issue: 6497 Vol. 368; ISSN 0036-8075
Publisher:
AAASCopyright Statement
Country of Publication:
United States
Language:
English

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