Project Abstract
|
Even though the Elsinore Fault is subordinate to the San Andreas and San Jacinto faults systems, it accommodates approximately 5 mm/yr of the total strain and as such poses a significant geohazard for Southern California. We conducted a CHIRP seismic survey of Lake Elsinore to image this fault system, which was designed to complement the onshore paleoseismic investigations and allow for a more complete event characterization for this segment of the fault. The survey was designed to test whether events are multi-segment ruptures or if Lake Elsinore acts as a baffle that isolates the Glen Ivy Segment to the north from the Temecula Strand to the south (segment offset is ~2.5 km). Extensive radiocarbon dating of several long cores (>10 m) recovered from Lake Elsinore would have allowed us to establish a chronostratigraphic framework for the sedimentary sequences, the critical first step toward developing recurrence intervals. Even though our group has successfully employed this acoustic paleoseismic approach in several other tectonically active regions (Lake Tahoe; Kent et al., 2005, Dingler et al., 2009; Fallen Leaf Lake, Brothers et al., 2009; Offshore La Jolla, Hogarth et al., 2007; Le Dantec et al., 2011; Salton Sea, Brothers et al., 2009; 2011; Pyramid Lake and Great Salt Lake, in prep.), the surfical sediment in Lake Elsinore was gas charged, which precluded imaging the subsurface reflectors. After a day of surveying a regional grid in Lake Elsinore, we discovered that the gas-charge sediment was pervasive around the lake. |
