TY - JOUR
T1 - A new geological slip rate estimate for the Calico Fault, eastern California
T2 - implications for geodetic versus geologic rate estimates in the Eastern California Shear Zone
AU - Xie, Surui
AU - Gallant, Elisabeth
AU - Wetmore, Paul H.
AU - Figueiredo, Paula M.
AU - Owen, Lewis A.
AU - Rasmussen, Craig
AU - Malservisi, Rocco
AU - Dixon, Timothy H.
N1 - Funding Information:
This work was supported by the U.S. Geological Survey [G16AP00102 (PHW and THD), G16AP00103 (LAO)].
Funding Information:
This work was supported by the U.S. Geological Survey [G16AP00102 (PHW and THD), G16AP00103 (LAO)]. We acknowledge Amelia Nachbor of the University of South Florida for help with the field work, and Antonio Luna for help with some sample preparation. Sarah Hammer and Kat Rivers at the University of Cincinnati are also thanked for help in sample preparation. We thank OpenTopography for providing LiDAR raster data, and USGS for providing high-resolution aerial ortho-imagery. Mike Oskin, David Katopody, and an anonymous reviewer are thanked for their thoughtful comments.
Publisher Copyright:
© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.
PY - 2019/9/2
Y1 - 2019/9/2
N2 - Accurate estimation of fault slip rate is fundamental to seismic hazard assessment. Previous work suggested a discrepancy between short-term geodetic and long-term geologic slip rates in the Mojave Desert section of the Eastern California Shear Zone (ECSZ). Understanding the origin of this discrepancy can improve understanding of earthquake hazard and fault evolution. We measured offsets in alluvial fans along the Calico Fault near Newberry Springs, California, and used several techniques to date the offset landforms and determine a slip rate. Our preferred slip rate estimate is 3.2 ± 0.4 mm/yr, representing an average over the last few hundred thousand years, faster than previous estimates. Seismic hazard associated with this fault may therefore be higher than previously assumed. We discuss possible biases in the various slip rate estimates and discuss possible reasons for the rate discrepancy. We suggest that the ECSZ discrepancy is an artefact of limited data, and represents a combination of faster slip on the Calico Fault, off-fault deformation, unmapped fault strands, and uncertainties in the geologic rates that have been underestimated. Assuming our new rate estimate is correct and a fair amount (40%) of off-fault deformation occurs on major ECSZ faults, the summed geologic rate estimate across the Mojave section of the ECSZ is 10.5 ± 3.1 mm/yr, which is equivalent within uncertainties to the geodetic rate estimate.
AB - Accurate estimation of fault slip rate is fundamental to seismic hazard assessment. Previous work suggested a discrepancy between short-term geodetic and long-term geologic slip rates in the Mojave Desert section of the Eastern California Shear Zone (ECSZ). Understanding the origin of this discrepancy can improve understanding of earthquake hazard and fault evolution. We measured offsets in alluvial fans along the Calico Fault near Newberry Springs, California, and used several techniques to date the offset landforms and determine a slip rate. Our preferred slip rate estimate is 3.2 ± 0.4 mm/yr, representing an average over the last few hundred thousand years, faster than previous estimates. Seismic hazard associated with this fault may therefore be higher than previously assumed. We discuss possible biases in the various slip rate estimates and discuss possible reasons for the rate discrepancy. We suggest that the ECSZ discrepancy is an artefact of limited data, and represents a combination of faster slip on the Calico Fault, off-fault deformation, unmapped fault strands, and uncertainties in the geologic rates that have been underestimated. Assuming our new rate estimate is correct and a fair amount (40%) of off-fault deformation occurs on major ECSZ faults, the summed geologic rate estimate across the Mojave section of the ECSZ is 10.5 ± 3.1 mm/yr, which is equivalent within uncertainties to the geodetic rate estimate.
KW - Calico Fault
KW - Eastern California Shear Zone
KW - displacement
KW - geodetic slip rate
KW - geological slip rate
KW - surface exposure dating
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U2 - 10.1080/00206814.2018.1531272
DO - 10.1080/00206814.2018.1531272
M3 - Article
AN - SCOPUS:85047014665
SN - 0020-6814
VL - 61
SP - 1613
EP - 1641
JO - International Geology Review
JF - International Geology Review
IS - 13
ER -