Skip to Main Content
GEOREF RECORD

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

Samuel Y. Johnson, Stephen R. Hartwell and Peter Dartnell
Offset of latest Pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore Central California
Bulletin of the Seismological Society of America (August 2014) 104 (4): 1650-1662

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 approximately 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+ or -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. Online Material: (1) High-resolution bathymetric data for the cross-Hosgri slope and (2) metadata that describes data collection, processing, and formatting.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 104
Serial Issue: 4
Title: Offset of latest Pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore Central California
Affiliation: U. S. Geological Survey, Santa Cruz, CA, United States
Pages: 1650-1662
Published: 201408
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 42
Accession Number: 2014-071953
Categories: Structural geologySeismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N35°00'00" - N36°00'00", W122°00'00" - W121°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201438
Program Name: USGSOPNon-USGS publications with USGS authors
Close Modal

or Create an Account

Close Modal
Close Modal