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Scientists may not be able to say when, but they know one thing for sure—

A Tsunami is Coming

by Tracy Orillo-Donovan
Men run down street looking back over their shoulders at a wave crashing through palm trees

The wave flipped me over and carried me toward the lava rock wall that rimmed the school. I recall telling myself, “I'm going to hit head first into that rock wall and I'm going to die.” Miraculously, part of the wave that preceded me smashed into the wall and broke it up. So I went flying through the wall—rumbling along, rolling with all the rocks. I was under tons of water and I was getting hit by all these rolling rocks and debris, and I couldn't breathe. I was 16 but I guess I knew what mortality meant.

—Masuo Kino, survivor of the 1946 tsunami that hit the Big Island

It has been more than two decades since a tsunami hit the Hawaiian Islands and more than half a century since the most destructive tsunami on record. On April Fools' Day, 1946, an earthquake in Alaska's Aleutian Islands generated a tsunami. Waves more than 100 feet high raced across the Pacific, killing 159 people and causing more than $23 million in damages in Hawai'i. The run-up, or maximum height of the waves on shore, reached 54 feet on Moloka'i and 55 feet on the Big Island's Pololu. In some areas, waves penetrated more than a half mile inland.

Experts speculate that, because the tsunami happened on a day traditionally marked by pranks and jokes, few took the verbal warnings seriously. With no warning system in place, children headed to school, unaware of the threat. Curious onlookers, ignorant of the risk, ran toward the ocean instead of to higher ground.

Students cluster around a long clear acrylic tank

Tsunamis are a constant threat in the Pacific Basin. Between 1992 and 1998, 10 tsunamis killed more than 4,000 people and caused millions of dollars in damages. Warning centers—two in the United States and one each in Japan, French Polynesia, Pacific Russia, Chile and Peru—prevent even higher death tolls. “It's unlikely that another 1946 can catch us unaware,” says Gerard Fryer, a Hawai'i Institute of Geophysics and Planetology researcher who has investigated tsunamis for 14 years. Fryer and colleagues at Universtiy of Hawai'i and around the world are building better, more efficient prediction models to calculate the wave height and force of a tsunami approaching the Hawaiian Islands and other vulnerable locations. They study tsunamis originating in both local and distant events.

Local tsunamis, usually generated by landslides, can hit nearby land in a matter of minutes. Fryer, Hawai'i Undersea Research Lab's John Smith and Philip Watts of Applied Fluids Engineering, Inc., used mathematical calculations and prediction models to reproduce Hawai'i's two big local tsunamis, recorded in 1868 and 1975.

“We reproduced the run-ups for the 1975 tsunami very well, so we know our technique works,” says Fryer. “Now we are looking at every possible tsunami source around the Big Island, exploring what would happen and figuring out how severe the tsunami would be throughout the Hawaiian Islands.” The worst case scenario? If a big event, like the 1975 tsunami, occurred in South Kona, parts of Kailua-Kona would be flooded within six minutes and Honolulu, in a half hour. “We still have some thinking to do though,” says Fryer. “Our modeling says a 1951 Kona earthquake should have caused a damaging tsunami in Honolulu. There was a tsunami, but it was too small to do any damage.”

As they map areas that might be inundated, the team shares the information with Civil Defense officials so that sensible guidelines can be developed. Of special concern is Honolulu, where, because there is no record of damaging local tsunamis, there is no existing planned response to a large Big Island earthquake.

“We'll get all this work done within a year,” Fryer says. “Let's hope that's soon enough.”

Tsunamis from the margins of the Pacific have caused the most damage in Hawai'i. UHM Professor of Civil Engineering Michelle Teng and Professor of Ocean and Resources Engineering Kwok Fai Cheung are developing a software package to predict tsunami run-up and inundation patterns under different distant earthquake/tsunami scenarios, with funding from the Hawai'i Sea Grant College Program and Joint Institute for Marine and Atmospheric Research. A large wave tank provides laboratory data on wave run-up.

A new survey of the effects of the 1946 distant tsunami in the Marquesas Islands produced surprises. “The waves were far larger than they had been in Hawai'i, even though the Marquesas are a lot farther away,” Fryer says. “The waves were huge, averaging 20 feet and reaching as much as 65 feet in narrow valleys. It looks like a very narrow beam of extremely high waves was projected across the Pacific. The largest waves must have just missed Hawai'i but hit the Marquesas dead center.”

Just as researchers think they are solving the tsunami puzzle, new information raises new questions. They do agree on one fact—there will be another tsunami.

The whole road, everything was covered with debris. There was a house in the middle of the road. It looked like someone had taken all the furniture out of the house and put it underneath the house and sat the house down on top of it. I wanted to go see it, and they said, “No, no. Don't go over there.” I went anyway, and there was an arm in the debris. ...It was furniture and sticks and rocks and huge boulders and kitchen stuff and people and everything. It was the most amazing destruction I've ever seen.

—Jeanne Branch Johnston describing the aftermath of the April 1, 1946, tsunami in Hilo

Tracy Orillo-Donovan (BA '85, MEd '96 Manoa) is a public information officer in University and Community Relations

Tsunami facts

What does “tsunami” mean?

The Japanese word for “harbor wave” refers to a series of waves traveling across the ocean with extremely long wavelengths (up to hundreds of miles between wave crests in the deep ocean). Tsunamis have no connection with the weather nor with tides.

What causes a tsunami?

They usually result from a sudden rise or fall of a section of the earth's crust under or near the ocean. Volcanic activity and landslides above or below water can also generate tsunamis.

How fast do tsunamis travel?

A tsunami wave in the open ocean can reach speeds greater than 500 miles an hour. Locally-generated tsunamis can reach coastlines in minutes.

How manywaves are in a tsunami?

A tsunami generally consists of a series of waves, often referred to as the tsunami wave train. The amount of time between successive waves, known as the wave period, varies from only a few minutes to more than an hour.

What should I do?

Review evacuation zones and other information in the front pages of the telephone book now. If you are at the beach and feel an earthquake or observe a rapid withdrawal of the sea, head for higher ground immediately. When a tsunami warning is issued, keep telephone lines clear and stay away from low-lying areas.

Information courtesy of the Pacific Tsunami Museum.