SCEC Award Number 12198 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title SCEC 2012: Building a Holocene slip history for the Mojave section of the San Andreas Fault: Dating offsets near Oakdale and Shoemaker Canyons
Name Organization
Eric Cowgill University of California, Davis Kate Scharer United States Geological Survey Ryan Gold United States Geological Survey
Other Participants One additional PhD student.
SCEC Priorities 2a, 1d, 4c SCEC Groups Geology, WGCEP, SoSAFE
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
To test for possible temporal variation in slip rate and reconcile possible geodetic-geologic rate discrepancies, this project aims to help build a Holocene fault-slip history for the Mojave section of the San Andreas Fault by dating offset streams near Oakdale and Shoemaker Canyons. In detail we are using surficial geologic mapping, topographic data, excavations, and 14C geochronology to bracket measurements of both channel age and total offset at each site. Although our field studies have been delayed due to changes in personnel, in the last year we 1) obtained NSF funding to date landforms at 8 other sites, 2) constructed a preliminary slip history for the MSAF using Monte Carlo analysis of existing slip-rate data, 3) graduated MS student Tracy Compton, and 4) recruited a new PhD student, Mary Barr, to continue the project. We will conduct reconnaissance fieldwork along the MSAF at the end of March 2013 in preparation for a full season of work in summer 2013. We are currently converting a chapter of Tracy Compton’s MS thesis into a manuscript for submission in 2013.
Intellectual Merit This study, together with our new NSF-supported project, should yield enough new slip-rate data to enable us to construct a robust history of Holocene slip along MSAF, and thereby improve understanding of the apparently discrepant geodetic and geologic slip rates here. In addition, we are developing new insights into how to characterize the epistemic uncertainties associated with channel reconstructions.
Broader Impacts This SCEC project, along with project #11061, supported the MS thesis research for graduate student Tracy Compton. It will also support thesis research at Oakdale and Shoemaker Canyons by new PhD student Mary Barr. In addition, it continues to strengthen collaborative partnerships between researchers at UC Davis (PI Cowgill and student Mary Barr) and those at the USGS (Kate Scharer and Ryan Gold).
Exemplary Figure Figure 1. Preliminary fault-slip history for the Mojave section of the San Andreas Fault (MSAF) from present day to 4.5 ka derived from Monte Carlo analysis of existing slip-rate data. Figure modified from: Compton, T., 2012, Exploration of the Holocene record of fault slip for the Mojave section of the San Andreas Fault. M.S. Thesis, Geology Department, University of California Davis, 132 p.