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Probing California's Coastline to Unearth Traces of Paleotsunami

Robert J. Leeper, Brady P. Rhodes, & Matthew E. Kirby

Published November 17, 2012, SCEC Contribution #1838

Paleotsunami data along the California coast are rare and the data that do exist are limited to northern California. For a better understanding of the tsunami threat throughout central and southern California, prehistoric data need to be unearthed and documented in these regions. To accomplish this, the U.S. Geological Survey (USGS) has brought together scientists from California State University, Fullerton, California Geological Survey (CGS), Humboldt State University and the USGS to identify traces and develop a prehistoric tsunami inundation chronology. These data will provide geologic evidence to support the next Science Application for Risk Reduction (SAFRR) scenario, which will consider the effect on California of a tsunami generated by a major earthquake in the eastern Aleutian Islands. 
Research sites were determined by reviewing previous paleotsunami reconnaissance and research, considering coastal geomorphology and historic site-disturbance, and use of tsunami run-up data from the latest numerical tsunami models. These models were developed collaboratively by the CGS, California Emergency Management Agency, and the Tsunami Research Center at the University of Southern California. In response to a major earthquake in the eastern Aleutian Islands, one scenario results in wave elevations in excess of 9 m at some locations along the central and northern California coast, and 4 m in portions of southern California. In late July 2011, reconnaissance fieldwork commenced along the California coast and will continue throughout 2012. 

Results of the paleotsunami reconnaissance will set the stage for more in-depth research, which will get underway in early 2013. The final results of the study will be used by the State to better assess its tsunami hazard, especially for probabilistic tsunami hazard assessment, incorporated by SAFRR into the next scenario, and lay the foundation for future undergraduate and graduate level research in this field.

Leeper, R. J., Rhodes, B. P., & Kirby, M. E. (2012, 11). Probing California's Coastline to Unearth Traces of Paleotsunami. Oral Presentation at Southern California Conferences for Undergraduate Research.