Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California

Bulletin of the Seismological Society of America
By: , and 

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Abstract

The Hosgri fault is the southern part of the regional Hosgri–San Gregorio dextral strike‐slip fault system, which extends primarily in the offshore for about 400 km in central California. Between Morro Bay and San Simeon, high‐resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by an ∼265  m wide slope interpreted as the shoreface of a latest Pleistocene sand spit. This sand spit crossed an embayment and connected a western fault‐bounded bedrock peninsula and an eastern bedrock highland, a paleogeography resembling modern coastal geomorphology along the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6±0.9  mm/yr, considered a minimum rate for the Hosgri given the presence of an active western strand. This slip rate indicates that the Hosgri system takes up the largest share of the strike‐slip fault budget and is the most active strike‐slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high‐resolution bathymetry in characterization of active offshore faults.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120130257
Volume 104
Issue 4
Year Published 2014
Language English
Publisher Seismological Society of America
Contributing office(s) Pacific Coastal and Marine Science Center
Description 13 p.
First page 1650
Last page 1662
Country United States
State California
Other Geospatial Hosgri-San Gregorio fault
Online Only (Y/N) N
Additional Online Files (Y/N) N