"Except that we told them not to use the word 'tsunami,' " said John M. Cummings III, a spokesman for O'ahu Civil Defense. "We were afraid there would be people who would hear 'tsunami' and not hear the 'test' part."

The statewide tsunami-warning exercise, which did not involve public participation, was organized and coordinated by State Civil Defense. Ed Teixeira, vice director of that agency, said it went well.

"It was a very, very successful exercise," he said.

The exercise kicks off tsunami awareness month in Hawai'i and was designed to get key agencies, organizations and businesses to examine policies and procedures.

Transportation issues, he said, are likely to need the most work, and state, local and federal agencies will need to work together to coordinate air, ground and water transportation, he said.

Small-boat owners should be making decisions about what to do about their vessels in the event of a tsunami.

In the scenario used for the exercise, Teixeira said, the Pacific Tsunami Warning Center was able to not only predict the arrival time of the wave — 2:45 p.m., three hours after the siren sounded — it was also able to predict the approximate size of the wave.

"We were looking at 3 to 7 meters above normal," he said. "That is pretty significant."

The ability to forecast a tsunami with that degree of precision is a relatively recent event.

In 1994, Waikiki shorelines were evacuated after a tsunami was predicted to hit the Islands following a seismic event in Alaska.

The wave came, but it was so small it wasn't even noticeable. Waikiki businesses suffered because of the evacuation, not the tsunami.

The National Weather Service's system of six Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, stationed around the Pacific, are designed to help avoid such a situation.

But two of the six high-tech sensor buoys that make the Pacific Rim tsunami detection system a prototype for the world have been inoperative for the past 17 months, according to the National Weather Service.

Both broken buoys are off the coast of Alaska, a hot spot for generating tsunamis aimed at Hawai'i.

A third buoy in the Alaskan gulf remains operable, and Teixeira said that in the exercise scenario, that buoy provided the necessary information.

Ralph J. "Jeff" LaDouce, director of the National Weather Service, Pacific Region, said the two broken buoys would not endanger Hawai'i.

"We'll replace them once we have good weather," he said.

LaDouce said the third buoy near Alaska and other aspects of the detection system, including seismographs and scattered tide monitors, would give scientists plenty of warning if any tsunami were generated.

It might not, he said, give them enough information to decide that no damaging wave has been formed.

"It will increase the probability of a false alarm," he said. "If we can't determine there is no tsunami, we will consider a tsunami to have been formed, and look at other data to take the warning down."