History1920sCalifornia, USAlow confidence

The St. Francis Dam in California, built by self-taught engineer William Mulholland, was constructed on a defective foundation with the surrounding canyon geology ignored.

Notes on verification

Multiple independent, high-quality sources (Britannica, Smithsonian, Geo-Institute, ASDSO case study) corroborate Mulholland's self-taught background and the failure to conduct adequate geological investigation, leading to the dam's collapse on unstable foundations.

Sources