THE REPORTED CALIFORNIA TSUNAMI OF DECEMBER 1812

by

V. J. Grauzinis, J. W. Joy, and R. R. Putz

Marine Advisors, Inc.

ABSTRACT

The largest California tsunami of local origin reported in the literature is that of December 21, 1812, in the Santa Barbara Coast region. Run-up heights of up to 50 feet have been ascribed recently to this event.

This paper shows that the run-up projections are based upon latter-day accounts and reminiscences taken at face value. No corroboration for those accounts has been found in the contemporary historical record; there is no mention of any effects upon the ocean from the well-documented earthquakes of 1812-1813, other than a single statement that "the sea was agitated" at San Buenaventura. The latter-day accounts are shown to be variously erroneous, distorted or exaggerated, at best.

Even in the absence of explicit contemporary evidence, reasons are given for believing that a tsunami did occur. A reconciliation of the entire body of evidence suggests that the latter-day accounts may have been prompted originally by a more moderate tsunami, not generally noticed by the coastal population.

*published in the Environmental Impact Report for San Onofre Nuclear Generating Power Station, 1965