What is the name of the largest earthquake in the United States?

The largest earthquake in United States history was the 1964 Alaska earthquake. Also called the Great Alaska earthquake or Good Friday earthquake, it struck southern Alaska on March 27, 1964, with a moment magnitude of about 9.2.

The earthquake began near Prince William Sound and lasted approximately four and a half minutes. It resulted from a megathrust rupture where the Pacific Plate was forced beneath the North American Plate. Roughly 600 miles of fault moved, producing landslides, soil liquefaction, ground fissures, and major changes in land elevation.

Tsunamis generated by the seafloor movement caused many of the fatalities, including deaths in Alaska, Oregon, and California. Anchorage suffered severe damage, while parts of the Alaskan coast were permanently uplifted or lowered. The 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake were historically important, but neither approached Alaska's magnitude.