Global Positioning System tracking of slip rate of the Imperial, Elsinore/Laguna Salada, San Jacinto/ Weinert, Agua Blanca, and San Miguel Faults near the U.S.-Mexico border

Event Center A & B

In this study, the slip rates of the Imperial, Elsinore, Agua Blanca, and San Miguel Faults were investigated. This was done by using available GPS site velocities in the Imperial Valley. From my research using GPS site velocities and elastic modeling, I have calculated the following slip rates: Imperial Fault-30 mm/yr; Elsinore (Laguna Salada) Fault-2 mm/yr; Agua Blanca Fault-1 mm/yr; San Miguel Fault-4 mm/yr; Weinert Fault-5 mm/yr; Unnamed Fault-2 mm/yr. Results were found by comparing observed GPS velocities with velocities predicted from an elastic model for various fault slip rates and locking depths for the faults studied. Within the model, slip rates and locking depths were manipulated until a line of best fit was found. In most cases, my slip rates agreed with published studies. The one major discrepancy is for the Imperial fault. From my research, using GPS, I calculated a slip rate of 30 mm/yr, while Thomas and Rockwell (1996) calculated a slip rate of 15-20 mm/yr using an offset channel that was 300- 500 years old.