The ground shook so hard and for so long that Bob Eads could barely walk. He and his brother were at work on a construction project in Seward, Alaska, when North America's most powerful recorded earthquake struck. They saw a huge wave rise in Resurrection Bay. They dashed to their vehicles and tried to outrun it. Within seconds, Mr. Eads's car and his brother's truck were covered in 15 feet of water, filthy with debris and oil.
"It turned like midnight," says Eads, who still lives in Seward 41 years later. "It was completely dark underneath that dirty water that was coming up."
The Good Friday earthquake of March 1964 and the tsunamis that followed killed 131 people in Alaska, Oregon, and California. The town of Seward slipped about 47 feet south, while parts of Montague Island rose more than 30 feet. A National Academy of Sciences study found that the earthquake - a seismic event even stronger than the one behind last month's Asian tsunami - killed 90 percent of the mussels in Prince William Sound. But along with devastation came a clamor for warning and a push for change, and in the years since, Seward and other towns dotting the Alaskan coast have come up with a tsunami-warning system that includes everything from evacuation signs to a contraption that calls every house in town - methods that authorities in other vulnerable areas may strive to emulate in the months to come.
From Kodiak, Alaska, which was nearly obliterated in 1964, to Crescent City, Calif., where 11 people perished, 11 US cities are now recognized by the National Weather Service as "TsunamiReady."
Similar to an older StormReady plan, the TsunamiReady program details measures to prepare for and respond to the huge waves. Criteria include multiple methods for receiving and disseminating emergency information, maintenance of a 24-hour-a-day emergency warning system, and designated evacuation routes, many of which were designed with the help of computer-generated maps that predict flooding patterns.
A special siren signal is tested regularly, a trumpet of disaster, but also of a system that residents hope will keep them safe when the next tsunami comes. "It has a certain cadence, and we all know what that is, what that means," Eads says.
Brochures at hotels and campgrounds teach tsunami readiness; tour ships give out information, too - though Eads wonders if passengers fully grasp the warnings. "I imagine the tourists ... think there's about the same possibility of an airplane falling on them," he says.
In seismically active Alaska, where two earthquakes of magnitude 2.5 or greater typically occur each day, tsunami detection is serious business. Whenever an earthquake of magnitude 7 or higher strikes, the National Weather Service issues an automatic tsunami watch from its station north of Anchorage.
National, state, and local agencies have a long history of cooperating on tsunami preparation, says Aimee Devaris, Alaska regional warning-program manager for the National Weather Service. In addition to the evacuation zones, emergency drills, and shelters up and down the Alaska coast, Ms. Devaris hopes to add a couple of towns each year to the TsunamiReady program.
Tsunamis predating recorded history have left their mark here, too: Layers of marine sand deposited in freshwater areas show that huge tsunamis have struck every few hundred years, says Gary Carver, a Kodiak-based paleoseismologist and professor emeritus at Humboldt State University in California. "The 1964 tsunami was just another of a long series of tsunamis that have affected this part of the coastline."
As experts remind residents, a tsunami need not begin in the ocean to be deadly - nor must earthquakes precede them. Several hunters died in the waves that struck Cook Inlet after the 1883 eruption of Mount Augustine Volcano. A dock worker was killed in Skagway in 1994 by a local tsunami that may have been triggered by an overloading of heavy equipment on the tidal mud flats.
Nor do generating earthquakes need to be massive. The waves that swept through Seward in 1964 came from landslides within Resurrection Bay that were triggered by the initial earthquake in nearby Prince William Sound; a wave that wrecked Valdez was formed by the earthquake-triggered collapse of a glacial moraine.
"It's very important for people to know that a smaller magnitude earthquake can generate a tsunami on a local basis," Devaris said. "If you are in a low-lying coastal area and there is an earthquake where there's so much shaking that it's difficult to stand, don't wait for a warning. Evacuate."