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Thursday, June 3, 1999



State tsunami advisers
covet wave-height
forecasting system

By Helen Altonn
Star-Bulletin

Tapa

Japan's tsunami scientists now are able to forecast tsunami wave heights in different coastal areas -- a significant advance in warning technology.

"Unfortunately, we do not have that ability in Hawaii," said Daniel A. Walker, Oahu Civil Defense Agency tsunami adviser.

The Japanese development was discussed at a recent symposium here sponsored by the Tsunami Society and attended by specialists from around the world.

Walker said Japan's computer scientists are able to model tsunamis with information on bathymetry -- the ocean's landscape and depth -- and the location and causes of earthquakes.

"They can actually do a pretty good job of predicting what wave heights will be at different shorelines," he said.

Lives can be saved without knowing the exact height of arriving waves if people obey sirens and evacuation orders, said state tsunami adviser Gus Furumoto.

But more accurate descriptions are needed of how high waves will be from beach to beach to determine where the most damage or flooding will occur, he said.

The existing forecast system is based on past tsunamis, and is like a football prediction he said. "Notre Dame vs. Hawaii. We know Notre Dame is going to win, but by how much? Like a tsunami, we want to know how high it's going to be."

That can be done with more calculations, Furumoto said. "It's just a matter of hiring people to do it."


FABULOUS FIVE

Five retired scientists -- four from Hawaii and one from Colorado -- have been recognized by the Tsunami Society for continuing to make "outstanding and original contributions to the science of tsunami hazards." They are:

Bullet Doak Cox, who created Hawaii's first tsunami evacuation map and dedicated himself to collecting historical data on the effects of Hawaii tsunamis. His work provided a base for evaluating tsunami hazards and testing tsunami models.

Bullet George Curtis, tsunami adviser to the Big Island Civil Defense Agency, who spent a decade developing the present Hawaii tsunami evacuation maps in the telephone book.

Bullet Gus Furumoto, state tsunami adviser, who developed a method for evaluating the tsunami risk to Hawaii based on an earthquake's source.

Bullet Dan Walker, Oahu Civil Defense tsunami adviser, who used his own money to develop tsunami hazard literature and has taught thousands of children how to save their lives in the event of a tsunami. He also developed and placed tsunami inundation measurement devices across the state at his own expense.

Bullet James Lander of Boulder, Colo., formerly with the National Oceanic and Atmospheric Administration, for major work in collecting tsunami data and alerting areas of the world, such as the Caribbean, to the tsunami hazards they face.

Source: Star-Bulletin staff


Walker said he, Furumoto and other tsunami researchers have gotten together at civil defense meetings and had their own symposiums to discuss the local warning system.

They're advocating computer modeling to improve long-distance tsunami forecasting, more instrumentation to improve the local warning system, and more student and public educational programs.

Walker said he couldn't estimate how much it would cost to develop tsunami forecast models, but believes it would be less than $1 million.

"I do know a false warning costs the state about $30 million," he said, stressing that money spent to reduce or eliminate the possibility of false alerts and provide more precise warnings would result in state savings.

Improved forecast capability particularly is needed for earthquakes originating at the Big Island because of the short warning time for a tsunami generated there, Walker said.

In less than five minutes, a significant tsunami could hit Punaluu where busloads of tourists arrive daily to enjoy the black sand beach, he said.

There are only a couple tide gauges on the Big Island, Walker said. "A lot of people say if you feel the ground shake, that is your warning on the Big Island."

But a tsunami threat can't be based only on an earthquake's magnitude, he said, pointing out most large earthquakes don't produce tsunamis.

Several Big Island earthquakes this century were so small nobody could feel them, but they generated 10- to 14-foot waves, he said.

Hawaii has had a long history of tsunamis, Walker said, "but nature is playing a trick on us. We just haven't had any in a long time, so we have a lack of public awareness."

He said a point made at the symposium was: "You can have the best system in the world, but if people don't understand the unique destructive potential of tsunamis, as well as surfing waves, we're going to lose a lot of people in the next tsunami."

In 1994, he noted, a warning was issued before school started and an estimated 200 to 400 youths were in high North Shore surf when a tsunami was due to arrive.

"What kids don't understand is a tsunami is way different from a surfing wave in terms of its power and depth and currents generated," Walker said.

With Japan's new system, and computer modeling under way at various places to determine tsunami threats from an asteroid hitting the Earth, Walker said it "looks like we're going to be left in the dust" unless the state starts some modeling of its own.

Walker recalled the 1975 Kalapana earthquake that generated 45-foot waves within five minutes.

He said he asked a Los Alamos National Laboratory computer modeler what would happen if an earthquake similar to the Kalapana event occurred on the Kona Coast.

The answer: Tsunami waves 10 feet or higher could hit Oahu's southern shores within 30 minutes. That may not happen once in 50 or 100 years, Walker said, "but if we don't do this type of critical thinking, that's how these disasters occur."

He said the Pacific Tsunami Warning Center has made a lot of improvements but the ability to forecast wave heights offers the best potential for reducing "very, very dangerous" false warnings.

Warnings were issued for tsunamis in 1986 and 1994 that the public might have viewed as false because waves were only a few feet high with no destructive potential, Walker said.

A few such warnings over a shorter time could result in people ignoring them, and many would be killed if a significant event occurred, he said.

If a tsunami struck Hawaii as powerful as the April 1, 1946, tsunami that killed 159 people, Walker said, "the state would be belly-up. That would be it, the final blow."

The state's infrastructure and tourist industry would be wiped out since most utilities and other facilities are along the shoreline or in low-lying areas, he said.

"Yet, if we really had a proactive attitude in this state ... we could reduce fatalities and injuries and maintain our tourist industry and infrastructure without a whole lot of expense," Walker emphasized.

Simple earthen berms around essential structures could possibly save hundreds of millions of dollars, he said.

But he said, "If I had to bet my money, I would bet we'd probably have another false warning, or significant tsunami that would cause more loss of life than it should, before we take these steps to give us the system we need."



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