Historic Earthquakes

Mammoth Lakes, California
1980 May 25 16:33, 16:49, 19:44 UTC
Magnitude 6.2, 5.9, 5.9

In the Mammoth Lakes region, property damage caused by these earthquakes (plus a another strong shock on May 27, 14:50 UTC) to schools, other public buildings, highways, and merchandise in stores has been estimated at $1.5 million. Nine people were injured by the two largest earthquakes, mainly from falling rocks. Landslides and rockfalls were common in this area and in Yosemite National Park.

The most severe property damage occurred at Mammoth Lakes: chimneys toppled, water mains broke, windows shattered, and plaster cracked. The 20-year old Mammoth Elementary School was damaged severely by faulting beneath the school building. Ground cracks were abundant in fill along both paved and dirt roads. A 17 km-long zone of discontinuous surface fractures associated with the Hilton Creek fault was observed. It had a net vertical displacement of less than 50 mm and more than 200 mm of slip on single fractures.

The first earthquake was felt over a large area of California and western Nevada--from Reno and Las Vegas, Nevada, to the coast at Los Angeles and San Francisco. The third shock was felt over a similar area. Hundreds of aftershocks, many of which were felt in the Mammoth Lakes area, occurred through 1980.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.