Scripps Institution of Oceanography

The Great Chilean Earthquake of 22 May1960 generated a tsunami that caused widespread damage along the Pacific Rim, including at Crescent City, CA. Coincidentally, the water level fluctuations at Crescent City were successfully recorded by two Stevens Type A-35 paper-chart water level recorders attached to float gauges in stilling wells that had been installed as part of a U.S. Army Corps of Engineers study of harbor seiche. Data from 11 May to 16 June 1960 is available on 35 paper rolls from each of two locations in the harbor, Citizen’s and Dutton’s docks.

Of the 70 available rolls, 22 were scanned and digitized, 11 at each of the two docks. The digitized data cover the time period from 17:34, 20 May to 08:32, 31 May 1960 (PST). Digitization was performed at a sample rate of 1 Hz allowing high resolution analysis of the data, in sharp contrast to the tide gage data available at the time with a typical sampling interval of 1 hour.

This report documents the procedures used to obtain the digital time series of water levels at the two docks. The original paper chart records are in the custody of the San Francisco District, U.S. Army Corps of Engineers.