Why the St. Francis Dam Collapsed

Scientific American | June 1st, 1928

St. Francis dam was constructed on the San Francisquito fault, a geological feature known for a number of years and made the subject of publication illustrated by map

St. Francis dam was constructed on the San Francisquito fault, a geological feature known for a number of years and made the subject of publication illustrated by maps, chief among these being that published several years ago by the Seismological Society of America, which shows the major faults of  California. This statement, made March 22nd by Harry R. Johnson, consulting geologist of Los Angeles, speaking in San Francisco before the delegates to the convention of the American Association of Petroleum Geologists, created a profound impression, accompanied as it was by an analysis of the condition of the fault at that particular place. Mr. Johnson prefaced his report by saying that the advisability of making it had been discussed with other delegates, and that it had been decided that such a public report was advisable in view of the fact that "the public mind had been deluged by the wildest assortment of theories as to the cause of the catastrophe."