No ocean, no waves, no worries? Not quite

KANSAS CITY, Mo. -- You may think tsunamis, like the devastating one in the Indian Ocean in late December, are a threat far removed from U.S. shores.

Think again.

More than half of all Americans -- 152 million people -- live in coastal counties, including those along the Gulf of Mexico and the Great Lakes. And none of those counties, scientists say, is immune from a tsunami.

That's because tsunamis don't just happen in oceans. They can occur in lakes, rivers and even in reservoirs.

"Anywhere you have a steep slope next to a lake, or a lake with landslide potential, there are tsunami hazards," said Philip Watts, a tsunami scientist and consultant in Long Beach, Calif., who has written about the possibilities of West Coast earthquakes, landslides and tsunamis.

The insurance industry has even estimated the potential losses from tsunamis in the United States. It's $3 trillion per coastline, and almost none of it is covered, said Loretta Worters, vice president of the Insurance Information Institute.

Tsunami losses would be categorized as floods, which are not covered by most homeowner and business property policies, she said.

"The only way to really mitigate the risk of a tsunami," Worters added, "is not to build in those areas."

Don't think it can happen here? Well, there's even a tsunami in Missouri's past -- the famous New Madrid earthquakes of 1811 and 1812, which made the Mississippi River run backward.

The four giant tremors spanning 53 days rang bells as far away as Boston.

"It actually changed the course of the Mississippi," said Paula Dunbar, a National Oceanic and Atmospheric Administration scientist in charge of compiling an online tsunami database. "That's the reason it's in there (the list of tsunamis)."

Worries about tsunamis striking the United States date to the 1960s, when warning systems were placed on the West Coast and in Alaska and Hawaii. In recent years, six high-tech tsunami-monitoring buoys were arrayed in the Pacific: three off the West Coast, two off Alaska and one at the equator.

That southernmost buoy is in the line of fire of frequent Pacific Ocean earthquakes off Chile and Peru, said Hal Mofjeld, a senior scientist at the National Oceanic and Atmospheric Administration.

In the aftermath of the Indian Ocean earthquakes, 32 additional tsunami buoys have been proposed at a cost of $37.5 million.

"Earthquake information is absolutely essential, but it's not sufficient," Mofjeld said. "That's why putting additional buoys out in the Pacific and doing computer modeling are needed as well."

None of those devices, however, is planned for the Atlantic Ocean.

"Nobody has thought much about tsunamis on the East Coast," Dunbar said. "It just has not been on anybody's radar screen until the last few years."

Scientists say that's because the Atlantic Ocean's floor does not have the jumble of colliding tectonic plates like the Pacific Ocean.

But some scientists point to two geological features in the Atlantic Ocean that they think pose the risk of tsunamis:

* Part of the Canary Islands, off the coast of Morocco, may be ready to fall into the ocean. Although more than 2,000 miles east of New York, such a landslide could transmit waves oceanwide.

* The Continental Shelf, where the ocean drops off sharply to its full depth, is a steep slope with landslide potential.

The Atlantic Ocean has spawned lethal tsunamis in the past.

A quake under the Grand Banks off Newfoundland in 1929 generated waves that hit the coast at 78 mph and killed 51 persons.

Watts said a landslide in the Canary Islands would present a similar threat, although not all scientists agree on how damaging it might be.

Tsunamis come in waves not a few feet wide, but a couple of miles. The waves rush inland, one after another, over the course of hours. And they move at hundreds of miles per hour.

On the earthquake-prone West Coast, state governments print brochures warning residents not to run to the beach in a tsunami. They should go to higher ground.

"Tsunamis move faster than a person can run," the Western States Seismic Policy Center warns. "Tsunamis are not surfable!"

Because of their massive power, tsunamis also are difficult to measure. Scientists try to gauge "runup" -- how high the water rises above sea level -- and "inundation" -- how far inland the water reaches.

"Both of these measurements, particularly historically, are hard to get," Dunbar said. Eyewitness reports are often the primary evidence for past tsunamis, she said.

As a result, scientists rank past tsunamis by "validity," from certain (four) to highly questionable (one) and unknown (minus one).

The New Madrid event has a validity ranking of three, because there were so many reports along the Mississippi River, Dunbar said.

Although tsunamis are unusual, Mofjeld said, everyone should be tsunami-savvy, even people who hale from the Heartland.

"People may live well away from the coast but vacation at the coast or have relatives near the coast," he explained. "Having an idea of what a tsunami is, recognizing its features and knowing what to do if a warning is sounded are all critical."

The deadly earthquake off Indonesia -- the fourth-largest recorded since 1900 -- jarred even landlocked Midwesterners into awareness about tsunamis.

"The most amazing thing to me about this whole thing is how little we knew, even geologists," said Ray Caveney, chairman of the geological sciences department at the University of Missouri-Kansas City.

Caveney said he has been talking a lot with students about tsunamis over the past few weeks.

"I know more about tsunamis now than I did a month ago," he said.