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Fault Friction Derived From Fault Bend Influence on Coseismic Slip During the 2019 Ridgecrest M_w 7.1 Mainshock

Milliner, C. W. D. and Aati, S. and Avouac, J. P. (2022) Fault Friction Derived From Fault Bend Influence on Coseismic Slip During the 2019 Ridgecrest M_w 7.1 Mainshock. Journal of Geophysical Research. Solid Earth, 127 (11). Art. No. e2022JB024519. ISSN 2169-9313. doi:10.1029/2022jb024519.

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The variation of stress on faults is important for our understanding of fault friction and the dynamics of earthquake ruptures. However, we still have little observational constraints on their absolute magnitude, or their variations in space and in time over the seismic cycle. Here we use a new geodetic imaging technique to measure the 3D coseismic slip vectors along the 2019 Ridgecrest surface ruptures and invert them for the coseismic stress state. We find that the coseismic stresses show an eastward rotation that becomes increasingly transtensional from south-to-north along the rupture, that matches the known background stress state. We find that the main fault near the M_w 7.1 mainshock hypocenter was critically stressed. Coseismic slip was maximum there and decreased gradually along strike as the fault became less optimally oriented due its curved geometry. The variations of slip and stress along the curved faults are used to infer the static and dynamic fault friction assuming Mohr-Coulomb failure. We find shear stresses of 4–9 MPa in the shallow crust (∼1.3 km depth) and that fault friction drops from a static, Byerlee-type, value of 0.61 ± 0.14 to a dynamic value of 0.29 ± 0.04 during seismic slip. These values explain quantitatively the slip variations along a transpressional fault bend.

Item Type:Article
Related URLs:
URLURL TypeDescription
Milliner, C. W. D.0000-0002-3790-595X
Aati, S.0000-0003-1087-832X
Avouac, J. P.0000-0002-3060-8442
Alternate Title:Fault Friction Derived From Fault Bend Influence on Coseismic Slip During the 2019 Ridgecrest Mw 7.1 Mainshock
Additional Information:We thank Jeanne Hardebeck, Xin Wang, Egill Hauksson and Shuzhong Sheng for making their stress results available. We thank Kim Olson, the editor Isabelle Manighetti, the associate editor and two anonymous reviewers for their comments and suggestions which helped strengthen the manuscript. We thank the NASA NGA commercial archive data service for access to the WorldView imagery ( which is provided under the NextView license agreement. This research was supported by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology (80NM0018D0004). Satellite imagery for this project were also purchased under SCEC Grant 19222.
Group:Division of Geological and Planetary Sciences, Seismological Laboratory
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)19222
Issue or Number:11
Record Number:CaltechAUTHORS:20221214-893781900.2
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118335
Deposited By: Research Services Depository
Deposited On:18 Jan 2023 16:07
Last Modified:18 Jan 2023 16:07

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