SCEC Award Number 13127 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Resolving Crustal Deformation in and around San Gorgonio Pass
Investigator(s)
Name Organization
Sally McGill California State University, San Bernardino Rick Bennett University of Arizona
Other Participants 1 Ph.D. student; 2 SCEC/SURE interns; 4 other undergraduates; 6 high school teachers; 6 high school students; Ken Hudnut (USGS) and Robert deGroot (SCEC) will also participate as collaborators. Hudnut't time and expensed will be paid by USGS; deGroot's time and expenses will be paid by his NASA grant.
SCEC Priorities 1, 4 SCEC Groups Geodesy, SoSAFE, SDOT
Report Due Date 03/15/2014 Date Report Submitted N/A
Project Abstract
 We have contributed significant new crustal motion data for the San Gorgonio Pass Special Fault Study Area, and have begun elastic block modeling of fault slip rates in this region. Mature velocities for 41 sites in CSUSB’s San Bernardino Mountains network are now available, based on NSF- and SCEC-funded work from 2002-2012 (McGill et al., in prep.). Of these, velocities for 21 sites are available for the first time, and velocities for another 19 sites have been updated, based on new GPS data collected between 2004 and 2013, which were not included in Shen et al.’s (2011) analysis. One+ dimensional modeling of the velocities from the San Bernardino Mountains network indicate a faster stressing rate for the San Jacinto fault (13.2 ± 1.5 mm/yr) than for the San Andreas fault (7.8 ± 1.7 mm/yr). During summer and fall 2013 we reoccupied 22 sites in the San Bernardino Mountains network, most of the Joshua Tree network and we observed 23 new sites at existing benchmarks in regions in and around San Gorgonio Pass where velocities were previously sparse. Of the new sites, 12 were observed both in summer and fall 2013, and we present here preliminary velocities (with large uncertainties). We hope to re-observe all 23 of these sites in spring or summer and fall 2014, with 2014 SCEC funding. These new velocities will densify the Community Geodetic Model within the San Gorgonio Pass Special Fault Study Area.
Intellectual Merit We have contributed significant new crustal motion data for the San Gorgonio Pass Special Fault Study Area, and have begun elastic block modeling of fault slip rates in this region. Mature velocities for 41 sites in CSUSB’s San Bernardino Mountains network are now available, based on NSF- and SCEC-funded work from 2002-2012 (McGill et al., in prep.). One+ dimensional modeling of the velocities from the San Bernardino Mountains network indicate a faster stressing rate for the San Jacinto fault (13.2 ± 1.5 mm/yr) than for the San Andreas fault (7.8 ± 1.7 mm/yr) (SCEC Science Objective 1a). During summer and fall 2013 we collected over 4500 hours of GPS data, reoccupying 22 sites in the San Bernardino Mountains network, 20 sites in the Joshua Tree network and observing 23 new sites at existing benchmarks in regions in and around San Gorgonio Pass where velocities were previously sparse. Of the new sites, 12 were observed both in summer and fall 2013, and we present here preliminary velocities (with large uncertainties). These new velocities will densify the Community Geodetic Model (SCEC Science Objective 1d) within the San Gorgonio Pass Special Fault Study Area (SCEC Science Objective 4a).
Broader Impacts Participants in the summer 2013 San Bernardino Mountains data collection campaign included two SCEC interns (from the south-central U.S.) and three CSUSB students funded by SCEC (one master’s student and two undergraduates who are using the GPS data collected for their senior research projects). Also participating were six CSUSB undergraduates supported by a grant from the NSF Mathematics Division’s program for Proactive Recruitment in Introductory Science and Mathematics (PRISM). A third set of participants included twelve high school and middle school science teachers and an employee of the San Bernardino County Museum. All travel and stipend support for these participants were covered by a NASA Insight grant on which Dr. Robert DeGroot is a co-PI.

As usual, educational activities provided for participants in the summer 2013 San Bernardino Mountains campaign included a field trip to active faults in the region as well as workshops that introduced the scientific goals of the project, that provided training in the operation of geodetic-quality GPS receivers and antennae, that allowed participants to plot time series for the stations that they occupied and to infer fault slip rates by conducting one-dimensional elastic modeling of the site velocities.

Participants in the 2013 Joshua Tree campaign included three graduate students and one undergraduate student from the University of Arizona, and one visiting faculty member from the University of Sinaloa, Mexico. The data collected served as the basis for a graduate student seminar focusing on GPS data analysis.
Exemplary Figure Figure 2: GPS sites within the San Gorgonio Pass Special Fault Study Area. Black squares show existing benchmarks that were observed with SCEC funding during summer and/or fall 2013. Dark gray vectors show preliminary velocities for those sites that were occupied in both summer and fall 2013. Uncertainties are presently large but will become smaller with additional occupations planned for 2014.