SE Asia disaster a wake-up call here

By Jan TenBruggencate
Advertiser Science Writer

Hawai'i has an active tsunami warning system, but it has been a generation since the last destructive tsunami, and officials fear most residents don't fully understand the danger they might face.

Hawai'i should know better. Tsunamis have killed 222 people here in the past 60 years. But the last deadly wave hit in 1975, 29 years ago.

The state faces two distinct tsunami threats: a wave generated from an earthquake or other event somewhere around the rim of the Pacific, and one generated locally, most likely near the Big Island. Both kinds have hit during the past century.

For a quake in Alaska, Hawai'i might have four to five hours' advance notice of an approaching tsunami, and from South America the delay might be half a day. But a local earthquake could generate a tsunami that could strike the Islands in a matter of minutes.

"Locally, people should heed Mother Nature's warnings," said Brian Yanagi, tsunami program manager for state Civil Defense. "If you're near the coast and you see the ocean water retreating, or you hear a sound like a freight train coming from the direction of the sea, or you feel the ground shaking, don't wait for official word. Get to high ground immediately. We generally say you're safe if you're half a mile inland in Hawai'i."

Charles "Chip" McCreery, geophysicist in charge at the National Oceanic and Atmospheric Administration's Pacific Tsunami Warning Center, said his agency's warning system for local earthquakes is mostly automated, and is capable of determining a quake's size and issuing an alert to Civil Defense authorities in as little as three to four minutes after a major event.

The Big Island has numerous tremor sensors and tide gauges that feed directly into McCreery's computers. A big shake triggers center staff members' pagers and sets off computers to calculate threat levels. Sirens could go off minutes later.

But people need to act fast, too. Officials recommend immediately turning on a radio for news if you hear the Civil Defense sirens. The phone directory contains maps of areas that need to be evacuated. To check for O'ahu maps online, go to www.honolulu.gov/ocda/maps.htm.

Coastal areas would need to be evacuated immediately. Sites nearest a major earth movement would have very little notice before getting slammed by a tsunami.

Campers at Halape on the Big Island had only seconds from the time a quake hit in 1975 to when a wave rolled ashore, killing two. A tsunami could wrap around the Big Island and cross the channel to Maui in less than half an hour, reaching O'ahu and Kaua'i 30 minutes to an hour later.

For quakes in more distant locations, there is a Pacific-wide array of sensing equipment.

McCreery said the first indication of a strong earthquake comes from 80 to 100 seismic stations spread around the Pacific. Computers monitor them constantly. A large quake sets off two or more stations, and the duty officers at the Pacific Tsunami Warning Center are immediately paged. They live on-site and can be in the office in as little as two minutes, McCreery said.

The next indications come from tide gauges near the quake site, which would show signs of any waves generated by the earthquake. Finally, there are buoys and ocean-floor pressure sensors that can detect a passing tsunami. These Deep-ocean Assessment and Reporting of Tsunamis (DART) systems automatically radio their data to satellites.

State Civil Defense Vice Director Ed Teixeira said the Islands are protected by three DART systems south of the Aleutian Islands and two between Hawai'i and the West Coast. He is anxious to have systems installed between Hawai'i and South America. Installation of gauges and sensors in other Pacific and even Indian Ocean nations is also critical, he said.

"This Indian Ocean event underscores the importance of the remote sensing equipment, and also demonstrates the need for us to be involved in tsunami work internationally," Teixeira said.

If a powerful tsunami has been generated, McCreery's staff alerts Teixeira's staff within a few minutes. Yanagi said Civil Defense aims for a minimum three-hour notice to evacuate. If it's rush hour, the agency might give more notice to ensure people have time to get out of tsunami inundation zones.

The notice generally takes the form of a steady, three-minute blast on the Civil Defense siren system. There are roughly 300 of these sirens situated in populated areas around the state. They are tested monthly, at 11:45 a.m. on the first state work day of the month. The next test siren sounding is scheduled for 11:45 a.m. Monday

If a particular siren is reported as not working, police cars will head into the neighborhood to get people evacuated. In remote areas without siren coverage, including remote coastal campsites on all islands, the Civil Air Patrol will dispatch planes capable of broadcasting evacuation notices by loudspeaker.

In every coastal location statewide except Waikiki, evacuation inland is recommended. There are so many people in Waikiki hotels that their mass evacuation might cause traffic jams. As a result, in that area alone, Civil Defense recommends "vertical evacuation" in reinforced concrete structures more than six stories tall. Hotel guests and staff are urged to move to the third floor or higher.

Teixeira said state Civil Defense held two tsunami exercises during 2004 and has another scheduled in April, which is Tsunami Awareness Month.

"I want the public to know that we take tsunami awareness seriously," he said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.