RESULTS FROM THE SAN BERNARDINO MOUNTAINS GPS NETWORK: VELOCITIES OF SITES IN THE VICINITY OF THE SAN ANDREAS FAULT IN SOUTHERN CALIFORNIA

In July 2013, a group of 11 undergraduates, 12 high school and middle school science teachers and one museum staff member set up GPS receivers and antennas over benchmarks to collect data at 34 locations in the San Bernardino Mountains and adjacent valleys and high desert terrain in San Bernardino and Riverside counties in Southern California. The data were collected in order to estimate the velocity of movement of the benchmarks due to bending of the Pacific and North American plates across the transform plate boundary. Previously published GPS data for southern California have a marked gap within the San Bernardino Mountains. Since 2002, our group has been collecting GPS data to fill in that gap. The velocities for most of our stations are now well constrained. Sites on both sides of the San Andreas Fault are moving northwestward, with sites farther southwest moving at a progressively faster rate as elastic strain accumulates across the locked faults of the plate boundary. Horizontal velocities (relative to stable North America) of sites within our study area range from 13.8 mm/yr in the northeastern section to 37.2 mm/yr in the southwestern section. Results of elastic modeling of our site velocities to infer fault slip rates are presented in a companion poster by W. Nelson and others.