History of earthquakes along the creeping section of the San Andreas Fault, California, USA

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, eart...

Full description

Saved in:
Bibliographic Details
Published in:Geology (Boulder) 2022-04, Vol.50 (4), p.516-521
Main Authors: Coffey, Genevieve L, Savage, Heather M, Polissar, Pratigya J, Cox, Stephen E, Hemming, Sidney R, Winckler, Gisela, Bradbury, Kelly K
Format: Article
Language:English
Subjects:
absolute age
active faults
argon
authigenic minerals
Biomarkers
California
cataclasites
Cenozoic
Central California
cores
coseismic processes
creep
degassing
displacements
Earthquakes
experimental studies
fabric
Fault lines
fault zones
faults
friction
geologic hazards
Geological faults
Geological hazards
Geology
gouge
Great Valley Sequence
heating
illite
K/Ar
kinetics
mathematical methods
Mesozoic
metamorphic rocks
methylphenanthrenes
Miocene
Monterey County California
natural hazards
Neogene
noble gases
numerical models
paleoseismicity
petrography
Pliocene
Quaternary
Radiometric dating
SAFOD
Salinian Block
San Andreas Fault
San Luis Obispo County California
Seismic activity
Seismic hazard
seismic risk
seismicity
Seismology
sheet silicates
silicates
temperature
Tertiary
thermal effects
thermal maturity
United States
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:0091-7613
1943-2682
DOI:10.1130/G49451.1