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Title: History of earthquakes along the creeping section of the San Andreas fault, California, USA
Abstract Creeping faults are difficult to assess for seismic hazard because they may participate in rupture even though they likely cannot nucleate large earthquakes. The creeping central section of the San Andreas fault in California (USA) has not participated in a historical large earthquake; however, earthquake ruptures nucleating in the locked northern and southern sections may propagate through the creeping section. We used biomarker thermal maturity and K/Ar dating on samples from the San Andreas Fault Observatory at Depth to look for evidence of earthquakes. Biomarkers show evidence of many earthquakes with displacements >1.5 m in and near a 3.5-m-wide patch of the fault. We show that K/Ar ages decrease with thermal maturity, and partial resetting occurs during coseismic heating. Therefore, measured ages provide a maximum constraint on earthquake age, and the youngest earthquakes here are younger than 3 Ma. Our results demonstrate that creeping faults may host large earthquakes over longer time scales.  more » « less
Award ID(s):
2126089 1358585
PAR ID:
10356089
Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Geology
Volume:
50
Issue:
4
ISSN:
0091-7613
Page Range / eLocation ID:
516 to 521
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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