Good Friday, March 27, 1964, was fairly unremarkable for the residents of Anchorage, Alaska. Most people were looking forward to a quiet spring holiday that late afternoon when the earth began to shake. It was one of the most powerful earthquakes of the twentieth century, and for four minutes enormous tremors rocked the city.

Geologist John R. Williams, who was relaxing in his apartment in Anchorage when the earthquake began, provides this account:

At first we noticed a rattling of the building. The initial shaking lasted perhaps five to ten seconds. The first shaking was followed without any noticeable quiet period by a strong rolling motion which appeared to move from east to west.

After a few seconds of the strong rolling motion, I took my son to the door leading to the hall, opened the door to prevent jamming, and stood in the doorway. I...