The most powerful earthquake in United States history was recorded 53 years ago this month. At 5:36 p.m. local time, a magnitude 9.2 earthquake occurred in the Prince William Sound region in Alaska on March 27, 1964.
In all, 139 people were believed to have died as a result of the earthquake. Fifteen died from the earthquake alone, while 106 died in Alaska, 13 died in California and five died in Oregon all related to tsunamis.
In addition to a tectonic tsunami, about 20 smaller and local tsunamis occurred. Smaller tsunamis were created by submarine and subaerial landslides, and tsunami waves were measured in over 20 countries including Peru, New Zealand, Papua New Guinea, Japan and Antarctica.
The earthquake rupture started approximately 15 miles beneath the surface, with its epicenter about 6 miles east of the mouth of College Fiord, 56 miles west of Valdez and 75 miles east of Anchorage. The earthquake lasted more than 4 minutes.
The largest earthquake ever recorded was a magnitude 9.5 in Chile in 1960, ahead of only the Alaskan earthquake.
About three hours after the earthquake, a 4.5-foot wave hit Prince Rupert, British Columbia and later reached the west coast of the Vancouver Island and traveled up to Port Alberni, washing away 55 homes and damaging 375 others. In days immediately after the earthquake, 11 aftershocks were recorded, each with a magnitude greater than 6.0. Aftershocks were felt for more than a year later.
While the earthquake was centered in Alaska, coastal towns in California and Oregon were heavily affected. Twelve people were killed by a tsunami in Crescent City, California, and four children were killed at Beverly Beach State Park in Oregon.
To learn more about tsunami risk and preparedness, visit the Cal OES Tsunami Preparedness webpage.
Cal OES provides information on earthquake, tsunami and volcano programs here.
Additional information about Tsunami Preparedness Week is available at www.tsunamizone.org.
Written by Jonathan Gudel