St. Francis Dam Disaster. Los Angeles County, California, USA. (12 March 1928)

güttsfükk · #1 ● 09-09-2012, 11:42 AM

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Colorized historic images by Pony R. Horton.

The St. Francis Dam was a curved concrete gravity dam, designed to create a reservoir as a storage point of the Los Angeles Aqueduct. It was located in San Francisquito Canyon, about 40 miles (64km) northwest of Los Angeles, California, approximately 10 miles (16km) north of the city of Santa Clarita. The name "St. Francis" is an anglicized version of the name of the canyon.

The dam was designed and built between 1924 and 1926 by the Los Angeles Department of Water and Power, then named the Bureau of Water Works and Supply. The department was under the supervision of the city's chief engineer William Mulholland.

At two and a half minutes before midnight on March 12, 1928 the dam failed catastrophically and the resulting flood killed up to 600 people. The collapse of the St. Francis Dam is considered to be one of the worst American civil engineering failures of the 20th century and remains the second-greatest loss of life in California's history, after the 1906 San Francisco Earthquake and fire. The disaster marked the end of Mulholland's career.

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Blocks of concrete weighing thousands of tons were carried in the floodwaters nearly a half mile downstream. The magnitude of the disaster is hard to comprehend. Normal rivers have trouble moving boulders only a foot across. Besides the sheer magnitude of the flow, debris from the landslide buoyed up the blocks. The block above was a half mile downstream. It measured approximately 63 feet long, 30 feet high, and 54 feet wide.