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Modeling High Stress Drops, Scaling, Interaction, and Irregularity of Repeating Earthquake Sequences Near Parkfield

Lui, Semechah K. Y. and Lapusta, Nadia (2018) Modeling High Stress Drops, Scaling, Interaction, and Irregularity of Repeating Earthquake Sequences Near Parkfield. Journal of Geophysical Research. Solid Earth, 123 (12). pp. 10854-10879. ISSN 2169-9313. doi:10.1029/2018jb016472.

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Repeating earthquake sequences have been actively investigated to clarify many aspects of earthquake physics. The two particularly well‐studied sequences, known as the Los Angeles and San Francisco repeaters, have several intriguing observations, including their long (for the seismic moment) recurrence times that would suggest stress drops of 300 MPa based on typical assumptions, near‐syncronized timing prior to 2004, and higher than typical inferred stress drops (of 25 to 65 MPa, up to 90 MPa locally), but not as high as the recurrence times suggest. Here we show that all these observations are self‐consistent, in the sense that they can be reproduced in a single fault model. The suitable models build on the standard rate‐and‐state fault models, with velocity‐weakening patches imbedded into a velocity‐strengthening region, by adding either enhanced dynamic weakening during seismic slip or elevated normal stress on the patches, or both, to allow for the higher stress drops. Such models are able to match the observed average properties of the San Francisco and Los Angeles repeaters, as well as the overall nontrivial scaling between the recurrence time and seismic moment exhibited by many repeating sequences as a whole, for reasonable parameter choices based on experiments and theoretical studies. These models are characterized by the occurrence of substantial and variable aseismic slip at the locations of the repeating sources, which explains their atypical relation between recurrence interval and seismic moment, induces variability in the repeating source properties as observed, and results in their neither slip‐ nor time‐predictable behavior.

Item Type:Article
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URLURL TypeDescription
Lui, Semechah K. Y.0000-0001-7801-3635
Lapusta, Nadia0000-0001-6558-0323
Additional Information:© 2018. American Geophysical Union. Received 30 JUL 2018. Accepted 9 NOV 2018. Accepted article online 14 NOV 2018. Published online 21 DEC 2018. This study was supported by the United States Geological Survey (grants G14AP00033 and G16AP00117), National Science Foundation (grant EAR 1520907), and Southern California Earthquake Center (SCEC, funded by NSF Cooperative agreement EAR‐0529922 and USGS Cooperative agreement 07HAQG0008). We thank Ting Chen for sharing her simulations with enhanced dynamic weakening. We also thank Rachel Abercrombie, Jean‐Philippe Avouac, Ting Chen, Rob Clayton, William Ellsworth, Don Helmberger, Junle Jiang, and Victor Tsai for helpful discussions and comments to the manuscript. We appreciate the insightful comments from the Editor Yehuda Ben‐Zion, David Shelly, and another anonymous reviewer that helped us improve the manuscript. The numerical data that support the presented findings are available in the figures and tables of this manuscript.
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)UNSPECIFIED
Subject Keywords:repeating earthquake sequences; earthquake interaction; rate‐and‐state friction; aseismic slip; numerical simulations
Issue or Number:12
Record Number:CaltechAUTHORS:20190206-134734051
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Official Citation:Lui, S. K. Y., & Lapusta, N. (2018). Modeling high stress drops, scaling, interaction, and irregularity of repeating earthquake sequences near Parkfield. Journal of Geophysical Research: Solid Earth, 123, 10,854–10,879.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92741
Deposited By: George Porter
Deposited On:07 Feb 2019 15:39
Last Modified:15 Nov 2022 21:42

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