The northern San Jacinto Fault Zone

The goal of this work is to determine the fault slip history and earthquake potential of the northern San Jacinto Fault Zone.

Using a combination of field mapping, analysis of B4 LiDAR data, geochronology, and trenching we have calculations of the Quaternary slip-rate and slip-per-event over the past 200 years, and documented the history of ground-rupturing earthquakes on the northern San Jacinto fault.

Most of this work has been concentrated at two sites- the Quincy site, where we have made slip-per-event and slip-rate measurements, and the Mystic Lake site, where we have documented 15 pre-historic earthquakes in the upper 5m (~3500 yBP). This work has been done in collaboration with Sally McGill (CSUSB), Tom Rockwell (SDSU) and numerous students and Southern California Earthquake Center interns. See the recent papers on the publications page. This work has been funded by SCEC and a EHP grant from the USGS.

In addition to this slip-rate and paleoseismic work, two of my recent graduate students worked along the Claremont fault. Cary Wicker used OSL to date terrace deposits preserved in the San Timoteo Badlands to determine rates and patterns of vertical displacement along the fault. Scott Kenyon has mapped the tectonic geomorphology of the Claremont fault in the northernmost part of the badlands to look for evidence of the most recent ground rupturing earthquakes along the Claremont fault.

DEM showing faults (red) and study sites along the Claremont fault segment of the San Jacinto fault zone

1940 Air Photo of the Mystic Lake site showing major fault strands in black, and locations of trenches (yellow, red, white) from 2009, 2010, 2012, 2013.

Geologic map of the Quincy site showing fault strands in black