SCEC Award Number 19170 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Multidisciplinary investigation of determining channel incision ages in the Carrizo Plain, California.
Name Organization
Sinan Akciz California State University, Fullerton Matthew Kirby California State University, Fullerton
Other Participants 1 undergraduate student and 1 undergraduate lab technician
SCEC Priorities 1a, 5b, 5c SCEC Groups Geology, SAFS
Report Due Date 04/30/2020 Date Report Submitted 04/22/2020
Project Abstract
Offset channels are routinely used to determine slip rates and slip-per-earthquake measurements. When earthquake chronology data are not available, offset channels are sometimes used to infer recurrence intervals (Sieh & Jahns, 1984). The underlying assumption for such interpretations is that the frequency of channel formation in an arid, semi-arid setting is higher than the recurrence of large surface rupturing earthquakes. However, it is not explicit what the recurrence interval threshold should be to determine if such an assumption is considered credible. Paleoseismic data from the Carrizo section of the San Andreas Fault (SAF) indicates recurrence intervals between surface-rupturing earthquakes ranging between 45 and 145 years (Akciz et al., 2010). Did new channels in the Carrizo Plain form frequently enough to record individual earthquake slip? Did these new channels form during major heavy precipitation periods as suggested by Grant Ludwig et al. (2010)? We propose a preliminary multi-disciplinary investigation to collect seed paleoseismic and paleoclimatic data to determine the ages of the channel incision events along the Carrizo section of the SAF and compare it with local paleoclimate data to determine when and how new channels form in the Carrizo Plain. No field data was collected last summer due to the arrival of funds too close to the start of our academic year. We are pursuing opportunities to start the data collection as soon as CSUF approves research activities including field and lab work.
Intellectual Merit This project falls within proposal category A (Collaborative Proposals) of section 3.2.2 of the SCEC 2019 Science Plan. The project applies to Research Priority 1.a. (Refine the geologic slip rates on faults in Southern California, including offshore faults, and optimally combine the geologic data with geodetic measurements to constrain fault-based deformation models, accounting for observational and modeling uncertainties), Research Priority 5.b. (Place useful geologic bounds on the character and frequency of multi-segment and multi-fault ruptures of extreme magnitude) and research Priority 5.c. (Assess the limitations of long-term earthquake rupture forecasts by combining patterns of earthquake occurrence and strain accumulation with neotectonic and paleoseismic observations of the last millennium).

The proposed study will enable us to test the climatically-driven origin of the offset channels. This multidisciplinary investigation is a first of its kind, proposing to collect paleoclimate and paleoseismic data contemporaneously from the same broad region. It will provide data to assess the reliability of using geomorphic offset estimates to propose slip-per-earthquake estimates in the Carrizo Plain. This seed data will be used to submit a more comprehensive NSF proposal in the near future to collect similar data from other sagponds in the Cholame and Carrizo sections and other channels with different ages. The anticipated results will improve an important part of the data upon which current earthquake hazard assessment and forecast models for the south-central SAF are built, a primary step towards hazard mitigation.
Broader Impacts N/A
Exemplary Figure N/A