NSF-PRISM Scholars Use GPS to Investigate Fault Slip Rates in Southern California
Authors:Isabella Benitez, Carmina Diaz, Lowell Iporac, Marlene Noriega, Vanessa Vega
Mentor:Sally McGill, Professor of Geology and PRISM mentor for Geology , California State University San Bernardino
The NSF-funded PRISM (Proactive Recruitment in Introductory Science and Mathematics) program provides research experiences for freshmen and sophomore college students. PRISM scholars at California State University, San Bernardino have been gathering GPS data in order to study the tectonic shift of the Pacific and North American plates along two major faults: the San Andreas (SAF) and San Jacinto (SJF). This research has been ongoing since 2002 and is being used to measure the direction and rates of a number of survey benchmarks, from which we can model the rate at which the faults have been shifting. The San Bernardino Mountains region had previously not been sufficiently investigated due to difficulties in access and permitting. The GPS data collected in 2013 are being processed at the University of Arizona. We conducted one-dimensional elastic modeling using GPS data collected up through 2012. After ad hoc testing of a number of different slip rate combinations for 14 faults, with locking depths held fixed near the maximum depth of seismicity, we found that SAF and SJF are the fastest moving faults in Southern California with 10 mm/yr for SAF and 9 mm/yr for SJF. Other models, however, can also fit the data reasonably well with slip rates for either fault ranging from 0 to 20 mm/yr.