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Title: Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes

Abstract

We report that the Mendocino Triple Junction (MTJ), at the northern terminus of the San Andreas Fault system, is an actively deforming plate boundary region with poorly constrained estimates of seismic coupling on most offshore fault surfaces. Characteristically repeating earthquakes provide spatial and temporal descriptions of aseismic creep at the MTJ, including on the oceanic transform Mendocino Fault Zone (MFZ) as it subducts beneath North America. Using a dataset of earthquakes from 2008 to 2017, we find that the easternmost segment of the MFZ displays creep during this period at about 65% of the long-term slip rate. We also find creep at slower rates on the shallower strike-slip interface between the Pacific plate and the North American accretionary wedge, as well as on a fault that accommodates Gorda subplate internal deformation. Finally, after a nearby M5.7 earthquake in 2015, we observe a possible decrease in aseismic slip on the near-shore MFZ that lasts from 2015 to at least early 2017.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Berkeley Seismology Lab, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1479379
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 45; Journal Issue: 2; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Materna, Kathryn, Taira, Taka'aki, and Bürgmann, Roland. Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes. United States: N. p., 2018. Web. doi:10.1002/2017GL075899.
Materna, Kathryn, Taira, Taka'aki, & Bürgmann, Roland. Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes. United States. doi:10.1002/2017GL075899.
Materna, Kathryn, Taira, Taka'aki, and Bürgmann, Roland. Tue . "Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes". United States. doi:10.1002/2017GL075899. https://www.osti.gov/servlets/purl/1479379.
@article{osti_1479379,
title = {Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes},
author = {Materna, Kathryn and Taira, Taka'aki and Bürgmann, Roland},
abstractNote = {We report that the Mendocino Triple Junction (MTJ), at the northern terminus of the San Andreas Fault system, is an actively deforming plate boundary region with poorly constrained estimates of seismic coupling on most offshore fault surfaces. Characteristically repeating earthquakes provide spatial and temporal descriptions of aseismic creep at the MTJ, including on the oceanic transform Mendocino Fault Zone (MFZ) as it subducts beneath North America. Using a dataset of earthquakes from 2008 to 2017, we find that the easternmost segment of the MFZ displays creep during this period at about 65% of the long-term slip rate. We also find creep at slower rates on the shallower strike-slip interface between the Pacific plate and the North American accretionary wedge, as well as on a fault that accommodates Gorda subplate internal deformation. Finally, after a nearby M5.7 earthquake in 2015, we observe a possible decrease in aseismic slip on the near-shore MFZ that lasts from 2015 to at least early 2017.},
doi = {10.1002/2017GL075899},
journal = {Geophysical Research Letters},
number = 2,
volume = 45,
place = {United States},
year = {2018},
month = {1}
}

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