SCEC Award Number 12174 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Collaborative Research: Assessing slip rate variations on the Garlock fault using newly developed luminescence sediment dating
Investigator(s)
Name Organization
Edward Rhodes University of California, Los Angeles James Dolan University of Southern California Sally McGill California State University, San Bernardino
Other Participants Belinda Roder, graduate student, UCLA; Lee McAuliffe, graduate student, USC; Thomas Crane, graduate student, CSUSB
SCEC Priorities 4c, 2d, 2a SCEC Groups Geology, SDOT, EFP
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
 The project has progressed in a successful manner, with significant outcomes. This research represents a major step forward in the development and application of new methods to achieve routine reliable luminescence age estimates for paleoseismic and fault slip rate contexts on timescales of 10 years to 100,000 years in Southern California. We are also able to provide a slip-rate determination for the Garlock fault for at least one late Holocene time period.


Technical science outcomes


  • Successful multiple test pit excavation and sample collection at Christmas Canyon West, near Ridgecrest, CA (central Garlock fault)

  • Development and assessment of novel K-feldspar single grain “post-infrared IRSL” dating protocol

  • Evidence for increased slip rate for the central Garlock fault over the last 2000 years – on-going additional research determinations are in progress to reproduce and validate this finding




Training, communication and outreach outcomes


  • Three UCLA and one USC graduate students closely involved in research

  • Three UCLA undergraduate students participated in research including two female Hispanic students

  • Two publications published in peer-reviewed journals based on results from the previous SCEC funding cycle

  • Six presentations made at international and national conferences, plus three at SCEC 2012
Intellectual Merit This research contributes to the intellectual merit of SCEC in two ways. Firstly, we have developed a novel approach to dating the deposition of high-energy fluvial sediment typical of desert alluvial fans using IRSL of K-feldspar single grains. This approach represents a significant advance in comparison to existing methods based on quartz, that may be unreliable in many tectonic contexts. Secondly, by applying this method, we have produced a slip-rate estimate for the central Garlock fault over the last 2000 years that indicates a significantly higher rate than the Holocene average rate. This finding has profound implications for our understanding of fault dynamics and physical mechanisms.
Broader Impacts The broader impacts of this research include the training in specialized laboratory and field techniques of three UCLA and one USC graduate students, plus three UCLA undergraduate students, including two female Hispanic students. Our Christmas Canyon West site was used for field training of around 20 UCLA and CalTech graduate and undergraduate geophysics students. We have published 2 papers based on previous SCEC results, and made 6 presentations at international and national conferences, besides the SCEC annual meeting. The IRSL techniques that we have developed within this project are now being applied to other sites around the world to improve our understanding of fault slip rates, paleoseismic events and past climate episodes.
Exemplary Figure Figure 2. Single grain post-IR IRSL at 225ºC dating results for sample CCW11-A03, target 1a (see Fig. 3). Five grains shown in black have been excluded from the age calculation, as they are inconsistent with the 20 remaining grains, resulting either from incomplete zeroing (grain no. 5) or post-depositional intrusive grains (grain nos. 4, 10, 16, 17), probably translocated within the sediment by bioturbation, in particular by ant activity.