Better tsunami detectors planned for Indian, Pacific oceans

Researchersare workingto develop a network of ocean-floor and mobile sensors that would help detect tsunamis in the Indian and Pacific oceans.

The low-cost devices would complement deep-water tsunami-detection buoys, providing measurements and analysis of seismic movements more quickly and accurately than the buoys alone, said Louise Comfort, a University of Pittsburgh professor working on the project.

They would offer greater coverage of the oceans by filling in large gaps between buoys, allowing scientists to promptly alert officials of undersea earthquakes that could trigger tsunamis and endanger coastal areas, she said.

A magnitude-9 quake that ruptured the ocean floor off the Indonesian coast on Dec. 26, 2004, sent 10-metre-high waves across the Indian Ocean, killing at least 216,000 people in 11 countries.

The researchers devised the plan at workshops last week in Berkeley, Calif., and Maui in February, with a $200,000 US grant from the National Science Foundation.

They plan to submit a grant proposal to the NSF for $3 million to fund tests off the coasts of the United States and Indonesia.

"We need a combination of these ocean-floor sensors and deep-water buoys," said Comfort, who has conducted studies of emergency responses to most major earthquakes over the past two decades.

"The deep-water buoys are very effective on the vertical determination," she said. "What they're less effective, and almost not effective on, is picking up any seismic movement that is horizontal, and consequently the deep-water buoys miss tsunamis."

She said German buoys installed off the coast of Indonesia last summer failed to detect a July 17 tsunami that killed 600 people because there were too few of the buoys and they were placed too far from the earthquake site.

Two international agencies issued warnings that the powerful earthquake could create destructive waves, but Indonesian officials did not pass them to local communities in time.

Motion, depth, speed measured

Comfort said that under her team's proposal, the new sensor network would be integrated with a communications system.

The sensors would be placed on the sea bottom or sent gliding through the water to collect three measurements: seismic motion, water depth and wave speed.

The network would offer an inexpensive alternative to buoys such as those in a U.S.-designed system to be placed in the Indian Ocean. The system is known as DART-2, for Deep-ocean Assessment and Reporting of Tsunamis. The Pacific system is called DART-1.

DART-1, co-ordinated by the Pacific Tsunami Warning Center in Hawaii and the Alaska Tsunami Warning Center in Palmer, Alaska, has buoys deployed mostly near U.S. territory, but collaborates with Japan, which has a sophisticated warning system.

"The huge expense is the maintenance of these buoys because they have to have a big oceangoing ship to visit them every year, change the batteries," Comfort said. "Nations like Indonesia and Thailand can't afford it."

A Pittsburgh computer professor, Taieb Znati, said the sensors would have computing ability that would enable them "to say something about what's going on in real time.

"They will facilitate the detection of earthquakes and things in a much shorter time," he said.