Tsunami-detecting capabilities in Hawai'i have been enhanced with the deployment of three, technologically advanced buoys.

The three Deep-ocean Assessment and Reporting of Tsunami, or DART, buoys off the coast of Mexico and Costa Rica are aimed at providing added tsunami detection capabilities for Hawai'i, Alaska, Guam, American Samoa and countries in the Pacific, said officials with the National Oceanic and Atmospheric Administration.

The announcement of the new buoys yesterday coincided with news that the death toll from the tsunami in the Solomon Islands, northeast of Australia, had risen to 28, with many more missing.

Also yesterday, Hawai'i civil defense officials carried out a successful tsunami drill with state, federal and county agencies responding to a mock disaster where a fictitious tsunami hits O'ahu half an hour after a Big Island earthquake.

With the addition of the three new buoys, the total U.S. network now consists of 28 stations. NOAA wants to have 39 in place by spring 2008.

Each buoy compiles seismic and water pressure data that scientists need to detect the origin and size of a fast-moving and destructive tsunami.

Barry Hirshorn, who was the lead geophysicist at the Pacific Tsunami Warning Center in 'Ewa Beach on Sunday morning Hawai'i time when the Solomon Islands earthquake hit, said the DART buoys were not a factor in their efforts trying to size up the tsunami generated by that tremor.

"For this particular case, they were of minimal help because the DART buoys were all up to the northeast of the Solomon Islands," Hirshorn said. "And the Solomon Islands land mass, as well as other things to the north, were blocking the tsunami from really affecting that part of the Pacific. What we really would have needed would have been things between the Solomon Islands and Australia, and Solomon Islands and New Zealand."

Still the local tsunami office did its part in monitoring and reporting on the events, Hirshorn said, using other devices.

TEMBLOR'S TRIGGER

The earthquake originated at 10:40 a.m. Hawai'i time. Two seismic sensors closest to the epicenter, in the Solomon Islands capital of Honiara, and Charter Towers, Australia, triggered the pagers of Hirshorn and other scientists in Hawai'i.

Scientists need information from four seismic or water-level stations before they can locate the origin and size of an earthquake.

The next stations to detect activity were in Funafuti, Tuvalu and Guam, and by 10:52 a.m., nine stations had reported. The Hawai'i crew was able to confirm the epicenter was in the Solomon Islands. By 10:54, data had been run through the computers showing a magnitude of 7.8. It was later revised to be an 8.1 temblor.

OUT OF DANGER

Hawai'i was under a tsunami advisory after the quake was detected, meaning it was more than six hours outside of the tsunami travel time.

By 12:26 p.m., additional data had come in showing the tsunami was headed "like a teardrop" toward northeastern Australia, and away from the northeastern Pacific, Hirshorn said.

"We realized it was safe to take everyone else out of the watch/warning/advisory mode," he said.

Hawai'i State Civil Defense Vice Director Ed Texeira said state and county civil defense officials began mobilizing shortly after 10:40 a.m. By 11 a.m., they received information from the tsunami center showing that Hawai'i would be placed only on advisory status and that there would not be any ill-effects here.

Nonetheless, "all of our county operations centers came up and were mobilized until such time as the Pacific Tsunami Warning Center canceled their advisory for Hawai'i," Texeira said. That was at about 12:45 p.m.

"The system worked," Texeira said.

April is Tsunami Awareness Month, and the state carried out the previously scheduled tsunami-response exercise yesterday as planned.

The drill, involving a fake earthquake and accompanying tsunami, went smoothly, Texeira said.

WARNING SIREN TIE-IN

The drill was timed to coincide with the testing of alert warning sirens that occur at 11:45 a.m. on the first working day of every month.

Under the mock scenario, an earthquake measuring 7.0 struck about six miles beneath the tiny town of Miloli'i in South Kona at 11:41 a.m. By 11:45, the warning center had alerted civil defense officials to begin mobilizing, and civil defense spokesman Ray Lovell was broadcasting to television and radio stations an explanation of why sirens were going off.

Under the scenario, 23 to 25 homes in Hawaiian Ocean View Estates were reported to be destroyed or damaged almost immediately, and the first waves of a tsunami would have hit O'ahu around 12:12 p.m.

Civil defense officials said the sirens are designed to alert the public to turn on their radios, televisions or computers to find out the reason for all the noise. They advised citizens that if they live in a low-lying area considered to be a tsunami-inundation zone, they should immediately move to higher ground and not wait for further notice.

The statewide drills are held twice a year, typically the first working day of April and October, Texeira said.