Tsunamis in the United States have hit Crescent City, Calif., 31 times since 1933.

The history behind current events.
March 11 2011 12:27 PM

Tsunami City, USA

Why is Crescent City, Calif., so susceptible to tsunamis?

The tsunami capital of the continental United States is Crescent City, Calif. (population 7,542), an economically depressed logging and fishing town just south of the Oregon border. Crescent City is predicted to be the California location hit hardest by the Japanese tsunami; one forecast predicts 7-foot waves, though so far the observed effect has been minimal.

Update, 2:28 p.m. ET: The Los Angeles Times reports 6.5-foot waves in Crescent City causing "significant damage" to boats in the harbor and "most of the docks" and flooding an inland creek. No reports yet of injuries or deaths. Larger surges may follow.

Update, 3:43 p.m. ET: Four people in Crescent City were reportedly swept out to sea, three injured and one believed dead.

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They've seen it before. Since 1933, 31 tsunamis have been observed in Crescent City. Four of those caused damage, and one of them, in March 1964, remains the "largest and most destructive recorded tsunami to ever strike the United States Pacific Coast," according to the University of Southern California's Tsunami Research Center. The 1964 tsunami killed 17 people on the West Coast, 11 of them in Crescent City.

Good Friday Earthquake, 1964. Click image to expand.
Fourth Avenue in Anchorage, Alaska, looking east from near D Street, after the 1964 earthquake

The 1964 tsunami was caused by the largest earthquake ever recorded in North America, and the second-largest ever recorded anywhere. The so-called Good Friday Earthquake, whose epicenter was just north of Alaska's Prince William Sound, registered 9.2 on the Richter scale and killed 115 Alaskans, inflicting its worst damage on Anchorage. Had it not struck during late afternoon on the Good Friday holiday, the death toll would probably have been much higher. All but nine of the deaths were caused not by the earthquake itself, but by the tsunami that resulted. (The tsunami also hit Canada, but no one there was killed.)

After Alaska, California, where the tsunami hit a little before midnight, was the state worst-hit by the 1964 wave. Total property damage there was $17 million (Oregon and Washington each sustained less than $1 million), of which fully $15 million occurred in Crescent City. According to Dennis M. Powers' 2005 account of the 1964 tsunami, The Raging Sea, in Crescent City "the disaster exceeded the combined effects of all previous death and destruction totals caused by tsunamis on the United States mainland and the greatest fatalities, injuries, and destruction ever reported on the West Coast." Although the earthquake killed many more people in Alaska than in Crescent City, the property damage per block ended up, weirdly, being greater in Crescent City.

Why is Crescent City so vulnerable to tsunamis? Apparently the main culprit is the Mendocino Fracture Zone, an underwater elevation extending westward that guides tsunamis into deeper water, where they pick up speed as they approach the mainland. The West Coast's topography around Crescent City curves inland, which intensifies a tsunami's effect, and the shoreline of Crescent City itself is (as the name suggests) a curve within that curve. The town's name is also, of course, the nickname of New Orleans, itself devastated by flood during 2005's Hurricane Katrina. One lesson would appear to be that if you want to stay dry, don't call the place where you live "Crescent City."

Timothy Noah is a former Slate staffer. His  book about income inequality is The Great Divergence.

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