FL MORRIS / FMORRIS@STARBULLETIN.COM Geophysicist Barry Hirshorn worked yesterday at the Pacific Tsunami Warning Center in Ewa Beach.

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Center’s technology
and staff ready to warn
isles of tsunamis

When it comes to tsunamis, think of the Hawaiian Islands as tempting bull's-eyes in the Pacific.

And think of them "not a matter of if, it's when" those bull's-eyes will get hit, said Brian Yanagi, earthquake/tsunami program manager for the state Civil Defense.

That is why the people in charge of looking over the horizon for destructive waves live only seconds from the Pacific Tsunami Warning Center in Ewa Beach, carry pagers at all times and have developed a network to warn residents of any impending tsunamis heading this way.

The center is equipped with several computers with sophisticated software that help track data from about 100 gauges and seismometers throughout the Pacific region. The center is manned around the clock. At least one tsunami scientist is known to jump on his bike when he is home and receives a pager alert, riding to the center in seconds.

When an earthquake of magnitude 7.0 or greater occurs locally or internationally, an urgent warning bulletin is issued to agencies that include the Civil Defense and the National Weather Service in Hawaii.

The center activates sirens to warn residents to turn on their TVs and radios alerting them of a potential tsunami.

The biggest hazard to Hawaii remains a giant tsunami from across the Pacific. But authorities say the warning system now is so good that Hawaii could get as many as three hours' warning.

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The islands also face the threat of a tsunami generated locally by an earthquake under the Mauna Loa or Kilauea volcanoes, which could give residents only minutes to seek higher ground.

But that threat would be mitigated by the placement of a seventh undersea tsunami detection device being planned for the Hawaiian Islands.

The six instruments that make up the 3-year-old Deep-Ocean Assessment and Reporting of Tsunamis system provide early warning to Hawaii and the U.S. West Coast.

Three of the instruments are placed near Alaska's Aleutian Islands chain. One is placed off Vancouver, British Columbia; one is off Oregon; and another is between Chile and Hawaii.

But despite the sophisticated equipment, Yanagi said residents and visitors along the coastline need to instinctively know to head inland should an earthquake occur.

Yanagi said sirens and the Emergency Alert System are tested every month. A simulated tsunami exercise is scheduled for April 1. Emergency tsunami plans and procedures will be tested based on a simulated earthquake in the Aleutian Islands.

The Pacific Tsunami Warning Center was created after an earthquake in the Aleutians generated a tsunami that killed 159 people in Hawaii in 1946.

Another tsunami warning center was built in Alaska following an earthquake that occurred in 1964 and killed 106 people in Alaska and 16 along the North American coast. No deaths were reported in Hawaii; however, damage occurred in Hilo and Kahului.

The Alaska warning center is responsible for warning residents in the Aleutian Islands, the West Coast and northwestern Canada.

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Big Isle not a main
source of tsunamis

HILO » Despite the Big Island's unstable geology, tsunamis generated on or near the island have caused less destruction than those that have come across the Pacific.

In the 20th century, 13 "significant" tsunamis hit Hawaii, the Pacific Tsunami Museum in Hilo says. The 1946 and 1960 tsunamis caused $49 million in damage.

Yet in the same century, only two significant tsunamis were generated on the Big Island, said University of Hawaii physicist George Curtis.

A tsunami on Nov. 29, 1975, centered at Halape in Hawaii Volcanoes National Park killed two people and caused $1.5 million in damage.

Another on May 30, 1924, did damage described as "great locally."

The worst Big Island tsunami came in the previous century, on April 2, 1868, killing 47 or 80 people, depending on the source of information.

All three of those events were in the Kilauea area, where geological conditions could produce a catastrophic earthquake and tsunami at some distant day in the future, experts believe.

A massive block of Kilauea, 12 miles long and 6 miles wide, is being slowly pushed seaward, says geologist Don Swanson, with the Hawaiian Volcano Observatory.

That is the kind of event that in the distant past caused enormous chunks of all of the Hawaiian islands to fall into the sea, undoubtedly creating giant tsunamis. But that was 100,000 to several million years ago, Swanson explained.

Such remote events are not worth worrying about, said Swanson, who advocates "worrying realistically." That means Big Islanders and their neighbors should be more concerned about events like those of 1868 and 1975.

Curtis, who advises Hawaii County Civil Defense on tsunamis, describes how water-level gauges have been placed along the Big Island coast, ready to radio the presence of a tsunami if a wave 10 feet or higher strikes.

That would provide warning time for Honolulu, although no tsunami generated on the Big Island has reached Honolulu in any significant size in historic times.

Big Island residents do not need such warning devices because the warning time will be too short, Curtis said. If they are near the coast and feel a big quake, they should automatically run inland, he said.

"The message is to run," he said.

Even if your legs will not save you, the "wrap-around effect" might. "Wrap-around" is what the Pacific Tsunami Museum calls the change in wave direction as a tsunami, like the one at Halape in 1975, went around Cape Kumukahi to get to Hilo or around South Point to get to Kona.

It lost energy in the process. The tsunami ran up to 45 feet above sea level at Halape but only to about 5 feet above sea level in Hilo and 8 feet in Kailua-Kona, Curtis said. But that was enough to smash boats in both locations.