SCEC Award Number 12172 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Pinon Flat Observatory: Continuous Monitoring of Crustal Deformation
Investigator(s)
Name Organization
Frank Wyatt University of California, San Diego Duncan Agnew University of California, San Diego
Other Participants Dai, John (undergraduate)
SCEC Priorities 5b, 2c, 1e SCEC Groups Geodesy, Transient Detection, SDOT
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
 The crustal deformation measurements at Pinon Flat Observatory, as with the strain measurements we make at other sites, provide data on otherwise unobservable deformation changes and the fault processes that produce them. The period following the 2010 El-Mayor/Cucapah earthquake has shown especially interesting signals, which we attribute to triggered aseismic slip on the San Jacinto fault: initially (over the first 50 days after the mainshock) the equivalent of a magnitude 5.6 event 15 km deep at the south end of the Anza seismic gap, in the same location as the postulated source of aseismic slip after the 2005 Anza earthquake. A subsequent strain episode, from October 2010 through October 2011, can be explained by aseismic slip equivalent to a magnitude 5.8 event at the location of the 2005 earthquake. At present the long-term strain rates on the PFO strainmeters appear to have returned to their long-term rates.
Intellectual Merit PFO continues to produce the highest-quality continuous crustal deformation data available anywhere, allowing us to:

(1) Improve our understanding of crustal deformation over time-spans from hours to years, including coseismic, postseismic, and interseismic changes; PFO's proximity to the San Andreas and San Jacinto faults gives an unmatched sensitivity for detecting slip there. The long span of the\s-1PFO\s0 records provides a unique basis for identifying and evaluating new signals.

(2) Provide independent high-quality data for interpreting other records from continuous GPS and borehole strain.
Broader Impacts Using undergraduates in the processing of data exposes them to science at a professional level (since their work will be used by the rest of the community). PFO provides a shared facility for the development of new technologies and new measurements: in the past year new rotational seismometers and fiber strainmeters. A field trip to PFO as part of the UNAVCO-sponsored three-day workshop on ``Strainmeter Science'' in La Jolla, October 10-12, 2012 helped to to bring together and advance the community of researchers working with strainmeter data,
Exemplary Figure Figure 3: Data from all three laser strainmeters at PFO since late 2008, showing two long-term strain events.