Abstract

Following a brief résumé of the historical record of the occupation of the Imperial Valley by people, and of the earthquakes reported felt, there are given estimates of the number of such shocks which are judged to pertain to the immediate region for the intervals (a) 1769 to June 10, 1902, and (b) June 10, 1902, through May, 1940; also the number of such shocks instrumentally recorded but not reported felt during the interval October, 1926, through May, 1940, with a few brief interruptions. These lists make it clear that the Valley region has long been markedly active, but not so greatly so as some similar districts elsewhere. Dates, and brief descriptions, are given for a number of the more important shocks, and the effect of the May 18, 1940, shock is appraised briefly.

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