Fox newsreel footage shows men setting the dynamite charges to blow up the "tombstone" (the center section of the dam that remained standing) and the wing dike, probably on April 17, 1929. (We see a portion of the wing dike
blow up here, but we don't see the tombstone collapse.)
Description: Preparations are being made to raise the center section of the dam that was left standing after its collapse. Huge caves are dug in concrete tower where the charges will be planted. Views of: preparing the charge on the upper wall; the battery setting off the blast; the explosion; the remaining center section of dam.
This film print was donated by Twentieth Century-Fox Film Corporation to the University of South Carolina. Used by permission.
Construction on the 600-foot-long, 185-foot-high St. Francis Dam started in August 1924. With a 12.5-billion-gallon capacity, the reservoir began to fill with water on March 1, 1926. It was completed two months later.
At 11:57:30 p.m. on March 12, 1928, the dam failed, sending a 180-foot-high wall of water crashing down San Francisquito Canyon. An estimated 411 people lay dead by the time the floodwaters reached the Pacific Ocean south of Ventura 5½ hours later.
It was the second-worst disaster in California history, after the great San Francisco earthquake and fire of 1906, in terms of lives lost — and America's worst civil engineering failure of the 20th Century.