Historic Earthquakes

Lituya Bay, Alaska
1958 07 10 06:15:53 UTC (Local 07/09)
Magnitude 7.7

This was the largest earthquake in southeast Alaska since the Yakutat shocks of 1899. The only permanent settlement in the epicentral region was Yakutat; therefore, effects on man-made works were moderate for such a large earthquake. On Khantaak Island (in Yakutat Bay), three persons were killed when the north end of the island slumped into the sea, and two people were missing and presumed dead in Lituya Bay from a wave generated by the collapse of 300 million cubic meters of rock into Gilbert Bay. At Yakutat, bridges, docks, and oil lines were damaged, a water tower fell, and a few cabins were destroyed. Many sand blows and ground fissures were observed on the low coastal plain southeast of Yakutat, and large landslides were reported in the mountains. A cabin collapsed and the ground was fissured at Dry Bay (East River); many sand blows and ground cracks occurred at Dry Bay (Akwe River); and submarine cables were severed in the Haines-Skagway area and at Lena Point (north of Juneau). Slight damage also occurred at Auke Bay, Barabof, Juneau, Pelican, and Sitka.

A massive rockslide at the head of Lituya Bay caused water to surge about 530 meters, generating a "gravity wave" that swept out of the bay. A fishing boat anchored in Anchorage Cove was carried in front of the largest wave crest, and those onboard estimated they cleared La Chaussee Spit (at the mouth of Lituya Bay) by 30 meters or more. Two people on another fishing boat disappeared after being caught in the huge wave. This major earthquake was felt over a large area of southeast Alaska, as far south as Seattle, Washington, and east to Whitehorse, Yukon Territory, Canada.

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.