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3D fault architecture controls the dynamism of earthquake swarms

Ross, Zachary E. and Cochran, Elizabeth S. and Trugman, Daniel T. and Smith, Jonathan D. (2020) 3D fault architecture controls the dynamism of earthquake swarms. Science, 368 (6497). pp. 1357-1361. ISSN 0036-8075. doi:10.1126/science.abb0779.

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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.

Item Type:Article
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URLURL TypeDescription Information InCaltech News
Ross, Zachary E.0000-0002-6343-8400
Cochran, Elizabeth S.0000-0003-2485-4484
Trugman, Daniel T.0000-0002-9296-4223
Smith, Jonathan D.0000-0002-1684-1344
Additional Information:© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works This is an article distributed under the terms of the Science Journals Default License. Received for publication January 28, 2020. Accepted for publication April 28, 2020. Z.E.R. was supported by the Southern California Earthquake Center (award 20018). D.T.T. acknowledges institutional support from the Laboratory Directed Research and Development (LDRD) program of Los Alamos National Laboratory (project number 20180700PRD1). Author contributions: Z.E.R. constructed the seismicity catalog; Z.E.R. and E.S.C. performed the spatiotemporal seismicity analysis; D.T.T. performed the magnitude and stress drop calculations; all authors contributed to general analysis and the writing of the paper. The authors declare no competing interests. Data and materials availability: The data used in this study are publicly available from the Southern California Seismic Network (38). The produced seismicity catalog will be publicly hosted at the Southern California Earthquake Data Center (38).
Group:Center for Geomechanics and Mitigation of Geohazards (GMG), Division of Geological and Planetary Sciences, Seismological Laboratory
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)20018
Los Alamos National Laboratory20180700PRD1
Issue or Number:6497
Record Number:CaltechAUTHORS:20200622-111633000
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Official Citation:3D fault architecture controls the dynamism of earthquake swarms BY ZACHARY E. ROSS, ELIZABETH S. COCHRAN, DANIEL T. TRUGMAN, JONATHAN D. SMITH Science 19 Jun 2020: Vol. 368, Issue 6497, pp. 1357-1361 DOI: 10.1126/science.abb0779
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103963
Deposited By: George Porter
Deposited On:22 Jun 2020 18:21
Last Modified:27 Feb 2023 17:44

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