A tsunami striking the U.S. is not a question of if but when

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W O R L D

Could It Happen Here? You Bet

A tsunami striking the U.S. is not a question of if but when

By J. MADELEINE NASH

 

 

 

Sunday, Jan. 02, 2005

Nothing even approaching last week's toll of death and destruction

has ever visited U.S. shores, but that doesn't mean North America

isn't vulnerable. Large tsunamis are not that rare, especially in the

Pacific, and every now and again, they crash into familiar ports of

call, sweeping away people and property. In 1960, for example, a

tremendous earthquake in Chile unleashed an armada of giant waves

that killed 61 people on the island of Hawaii and then moved on to

kill at least 100 more on Japan's Honshu Island. Four years later, a

tsunami triggered by an earthquake off the coast of Alaska resulted

in more than 100 deaths in Alaska, four in Oregon and 13 in

California, plus $100 million in property damage along the western

coasts of the U.S. and Canada.

 

And those are just the tsunamis in recent memory. The prehistoric

record is more disquieting. Geologist Brian Atwater of the U.S.

Geological Survey has assembled compelling evidence that as recently

as 300 years ago, huge tsunamis of shocking power pummeled the

Pacific Northwest, from California to British Columbia, reshaping

coastlines and surging far up rivers and streams. The culprit: an

undersea fault in the Cascadia subduction zone that bears more than a

passing resemblance to the fault that just ruptured off Sumatra.

 

" There are so many similarities between what happened there and what

could happen here, " says Vasily Titov, a tsunami modeler with the

National Oceanic and Atmospheric Administration in Seattle. " It's not

a question of if but when. "

 

The more scientists look into the tsunami threat to North America, in

fact, the larger it seems to loom. Hawaii not only sits in the path

of tsunamis that are generated around the Pacific—in 1946, a wave

unleashed by a temblor off the Aleutians killed some 170 people in

the city of Hilo—but it also harbors its own, homegrown threat.

 

Tsunamis can be triggered by massive landslides as well as

earthquakes, and University of Hawaii oceanographer Gary McMurtry has

evidence to suggest that about 120,000 years ago, a landslide

unleashed by the Mauna Loa volcano created a mega-tsunami that heaved

sand and sea fossils 1,600 ft. up the slopes of nearby Kohala.

 

The U.S. tsunami danger is not confined to the Pacific's hyperactive

Ring of Fire. In the Canary Islands, the western slope of the Cumbre

Vieja volcano poses a threat to Atlantic coastlines. Should it

collapse all of a piece, a scientist from University College London

warned last week, the big splash would send tsunamis coursing through

the Atlantic at hundreds of miles an hour. According to one nightmare

scenario, cities up and down the East Coast would be swamped by waves

as tall as five-story buildings.

 

Fortunately, tsunamis take time to travel, which can give populations

in harm's way anywhere from a few minutes to many hours to flee. For

this reason, 26 countries have banded together to establish a tsunami-

warning system for the Pacific (though not for the Atlantic Ocean or,

alas, the tsunami-ravaged Indian Ocean). As presently configured,

it's far from perfect, producing a 75% rate of false alarms. But that

should change with the deployment of a new generation of detectors

that can be positioned deep underwater, away from surface chop. In

November 2003, a trial run of the system determined that a tsunami

unleashed by an Alaskan earthquake would be too small to do any

damage when it reached Hawaii, thereby avoiding an unnecessary and

costly coastal evacuation like the one caused by a false alarm eight

years earlier. After last week's disaster, however, few are likely to

ignore the tsunami sirens the next time they sound.

 

 

From the Jan. 10, 2005 issue of TIME magazine