Tsunami watchers live to warn of big waves

Staff at the tracking center in Palmer await the big one they know is coming

Posted: Monday, July 09, 2001

ANCHORAGE - Alec Medbery waded through knee-high fireweed and dandelions to a granite outcropping overlooking the city of Palmer. Rattling his keys, he opened a door in a concrete wall under the big rock and snapped on a light bulb in a damp government-gray room with an orange cylinder sitting in the center.

That cylinder, little bigger than an oatmeal container, may save lives one day.

Medbery, an electronics experts at the West Coast and Alaska Tsunami Warning Center, was checking seismology equipment housed in the concrete bunker drilled into the hillside. And the small cylinder, which records seismic activity all over the world, is one of 25 seismometers in Alaska that are part of a Pacific-wide network for tracking earthquakes and the tsunamis they cause.

Tsunamis form when an earthquake near or under the ocean floor vertically displaces the Earth's surface. They also result from landslides, which may occur after an earthquake. The seismically active Pacific basin generates 100 or more earthquakes of magnitude 6.0 and higher each year. Traveling at speeds up to 600 mph, tsunamis can cross the ocean in less than 24 hours and wreak havoc when they reach land.

The big Alaska earthquake on Good Friday in 1964 killed 131 people in Alaska, Oregon and California - all but nine perished in the tsunami.

But many tsunamis go unnoticed since they can't be felt at sea or seen from the air. Their height only develops as they approach the rising underwater topography near a coastline. But they do make water levels rise and fall measurably as they pass over tide gauges throughout the Pacific. These readings, collected continuously, are used to predict how high tsunamis will be when they hit the coast.

To the staff at the warning center, those small waves are a dry run. They watch the Pacific from their building in Palmer - nondescript except for four tall antennae on the roof and a big satellite dish in the yard - and wait for the big one they know is coming.

The Alaska tracking center was established after the '64 quake. Located on bedrock, Palmer was an ideal location.

In those days, seismic and tide data were received by Teletype. Racing against time, scientists calculated the location and magnitude of earthquakes using slide rules. Information could take hours to be disseminated, too late to alert coastal communities close to an earthquake.

"All we could do was to warn people who were quite distant," said geophysicist Tom Sokolowski.

Sokolowski started doing tsunami research in 1965. His research group, stationed to the Pacific Tsunami Warning Center in Hawaii, came up with the idea to automate the tsunami warning system.

"I walked into my boss's office and told him I thought we should try to computerize," said Sokolowski. "He looked at me like I was crazy."

But his boss eventually bought the idea, and Sokolowski's team started to introduce computers into the tsunami prediction systems. When he transferred to Palmer in 1981, he brought techniques to automate systems to track earthquakes as they happen.

Now, when a quake strikes anywhere in the world, geophysicists at the center are ready. Computer screens display seismic waves emanating from the epicenter half a world away, picked up by seismometers in a dozen countries. By the time the impulse reaches the seismometer down the road in Palmer, they have a preliminary reading of the location and strength of the earthquake. Combined with data from tide monitors, tsunami predictions can be made in about 10 minutes.

Then there are the big "events." Tracking them from the Palmer site is like watching the pulse of the planet.

Sitting in front of a bank of 27 computer monitors, Paul Whitmore pointed out readings from a small earthquake occurring in Southern California.

"That's a little one, 2.5 to 3," said Whitmore. He pointed to squiggly lines on the screen. "Quakes that size happen all the time."

When the computers register a local quake above 4.0 on the Richter scale or a higher magnitude quake farther away, the center goes from being a scientific backwater to the epicenter of attention. All six employees are required to live less than five minutes from the center. Two are always on 24-hour call.

On June 23, when an earthquake measuring 8.2 struck Peru, pagers worn by Medbery and geophysicist Guy Urban started beeping. The two dropped what they were doing and rushed in to monitor seismic waves from the quake and issue recommendations to communities in the path of any resulting tsunami. Phones rang, radios buzzed and alarms beeped. On that Saturday, they advised coastal towns not to evacuate.

After the Peru quake, Whitmore was pleased. A computer program he'd written accurately predicted the height of waves reaching Adak 18 hours later.

"We said it would be 18 centimeters (7 inches), and that's what it was," he said. "We also accurately predicted the wave heights in Hawaii, but we were a little bit off for Crescent City, Calif."

But even speedy predictions don't help when earthquakes strike nearby and tsunamis follow almost immediately. So the National Weather Service has created a tsunami preparedness program for communities along the West Coast.

The program trains people living close to shore to run when the ground shakes strongly for more than 30 seconds. The goal is to get a mile from shore or 100 feet above sea level as soon as possible. According to Sokolowski, no matter how high the wave, the important thing is to get away from the water's edge.

"Don't go to the beach to watch," he said.

The first Alaska presentation will be in Seward in the fall. Towns that meet strict emergency requirements will be eligible to post a blue and white "Tsunami Ready" sign that pictures a figure running uphill from a big wave. Sokolowski hopes all coastal Alaska communities will be trained and ready soon.

"The whole thing is to save lives," he said.



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