Alaska’s Tsunami Warning Center at the Ready : Seismic activity: The last big waves, resulting from the state’s deadly 1964 earthquake, killed 121 people. The outpost monitors temblors across North America.

Geophysicists at the Alaska Tsunami Warning Center don’t flinch when earthquakes rattle the walls. In the heart of earthquake country, they put their fingers on Earth’s occasionally violent pulse and go to work.

The center’s seismometers and computer programs record earthquakes every day. They get small ones that measure 3.0 on the Richter scale of ground motion almost daily and 6.0 or higher about every other month. But what officials at North America’s premier tsunami--or seismic wave--outpost really are waiting for is the next Big One.

The last big one--and the biggest ever recorded in the United States--was Alaska’s 1964 Good Friday earthquake. It had a magnitude of 8.4.

The National Weather Service and National Oceanic and Atmospheric Administration established the center three years after the Good Friday quake and its resulting tsunamis destroyed several hundred million dollars of property and killed 132 people.

Of them, an estimated 121 people were killed by tsunamis.

Although scientists also monitor tsunamis for the western Pacific region in Hawaii, and a small tsunami center exists in Mexico, the Alaska center has responsibility for monitoring quakes and issuing tsunami warnings for all of North America. Its location is no accident.

“We said, ‘Let’s put it right smack in the middle of where it all occurs,’ ” said Thomas J. Sokolowski, chief geophysicist in charge of the Alaska Tsunami Warning Center.

The business of earthquake monitoring and tsunami prediction has come a long way since 1964, Sokolowski said. He cited the south coast of Alaska, where the Pacific tectonic plate dives deep beneath the North American plate.

“Now we know what’s causing it, with plate tectonics, etc.,” he said. “We understand plate movement--subduction--that it’s not uniform and that in some places it’s stuck. In some places it’s going to go.”

Employees of the tsunami center--who must live within five minutes of the center so they can respond quickly--can pinpoint the epicenter and estimate the magnitude of quakes within minutes. Two geophysicists are always on call, and monitoring equipment signals significant earthquake activity in the region.

And that is most of the time. Alaska is hit by more earthquakes than any other part of the United States.

On April 30, an earthquake measuring magnitude 6.0 was centered northwest of Palmer and south of Mt. McKinley--not more than 100 miles from Anchorage.

And although the 1964 quake was the last really giant one, Alaska recorded three of the strongest earthquakes in the world from 1904 to 1984. Since 1900, it has had more than two dozen over magnitude 7.0.

An earthquake measuring 5.0 can cause considerable damage in a populated area. A 6.0 quake can cause severe damage. Every increase of one number represents a tenfold increase in magnitude.

When there is a large earthquake, such as a 7.6 quake that struck the Yakutat area in the eastern Gulf of Alaska in 1987, the tsunami center issues a tsunami warning to coastal communities within minutes.

A series of wave motion and tide-measuring instruments in coastal areas determines if an actual tsunami has been generated. If not, the center cancels its warning, usually within 90 minutes.

“(When) we have something that’s potentially dangerous--we pull ‘em out,” Sokolowski said. Anything greater than magnitude 6.8 and the center calls for evacuation of areas near the epicenter. In the last five years, seven tsunami warnings have been issued in the Alaska region by earthquake watchers in Palmer.

The rule is an old one: better safe than sorry. Issuing warnings and then soon canceling them, however, is disconcerting and can be inconvenient.

Meanwhile, though scientists at the tsunami center are mostly concerned with the seismic waves that can result from major earthquakes or underwater volcanoes, others study just the earthquakes.

Scientists at the Alaska Seismic Studies Project at the U.S. Geological Survey in Menlo Park, Calif., work closely with the USGS National Earthquake Information Center in Colorado as well as scientists at the Geophysical Institute at the University of Alaska in Fairbanks to watch quake activity in the region.

They recently organized the Alaska Earthquake Information Center, based in Fairbanks and under the coordination of state seismologist John Davies, a university employee.

Seismologists at Menlo Park are convinced that a major earthquake, of magnitude 8.0 or greater, will strike the Gulf of Alaska near Yakutat sometime in the next 20 to 30 years.

“There should be enough accumulated strain in that area to produce a sizable earthquake,” said Robert Page of the seismology branch of the USGS in Menlo Park.

But Alaska doesn’t get the kind of attention it deserves from the world’s earthquake specialists, Page said.

The USGS maintained more seismographic stations in the Alaska region 10 years ago than it does today, he said. Most earthquake monitoring effort, time and money goes into studies to determine where the next big California earthquake will strike, he said.