The major earthquake and tsunami in Samoa and American Samoa caused some anxious hours for the Aloha State yesterday morning.

But within three hours of the quake, scientists at the Pacific Tsunami Warning Center in 'Ewa Beach were able to determine there was no serious threat to Hawai'i, and reduced what was then a tsunami watch to an advisory, thus eliminating the need to sound sirens and force the evacuation of thousands along the state's coastlines.

A decade ago, it might have been a different story and there likely would have been a full-scale evacuation of Hawai'i's coastal areas.

Technology has advanced to the point where scientists are able to determine much more quickly and accurately the speed, size and strength of tsunami waves following an earthquake, said Gerard Fryer, a geophysicist with the tsunami warning center.

"If this had happened a decade ago, Hawai'i would be in a warning," Fryer said.

But yesterday, the scientists were able to gather accurate enough data to allow them to move Hawai'i into an advisory mode that only cautioned people to stay away from beaches and the shoreline.

"We were able to make a forecast using numerical models of what we believed the impact would be in the state of Hawai'i," said Charles McCreery, director of the Pacific Tsunami Warning Center. "And for the state of Hawai'i, we could see, yes indeed tsunami waves were going to arrive here, but we did not expect them to be of a size that would cause major flooding or require a full evacuation of our coasts."

The center canceled its tsunami watch at 10:23 a.m. and issued an advisory.

A warning would have resulted in mass evacuations of the state's coastlines.

Peter Hirai, the city's deputy civil service director, recalled October 1994 when such a scenario did play out. An 8.1 earthquake off Russia's Kuril Islands triggered a tsunami warning in Hawai'i that led to a mass evacuation of the shorelines of all islands.

"It was another distant tsunami event, and not having the technology, we did do a general evacuation and the waves turned out to be pretty much the same result as today," Hirai said. "That one also turned out be pretty minimal wave action."

As of 5 p.m. yesterday, the highest sea level changes occurred at Hale'iwa (1.5 feet) and Kahului, Maui (1.2 feet).

Ray Lovell, public relations officer for state Civil Defense, remembered what happened in 1994 as well.

"It was early in the morning and the businesses didn't open, the kids didn't go to school, and everything stopped for that day," Lovell said.

The new technology helped saved the state millions in of dollars that might have been lost yesterday, he said.

Both Hirai and Lovell credit the arrival of Deep-ocean Assessment and Reporting of Tsunamis buoys in the earlier part of the decade for providing that upgrade in detection technology.

Geophysicists at the Pacific Tsunami Warning Center, however, said it's more than just the buoys.

Another critical detection tool that's been put in place is the use of tsunami forecasting modeling system that can predict the movement of tsunamis with better accuracy than in the past.

Coincidentally, three members of the Seattle-based Pacific Marine Environmental Library who developed the new models were on O'ahu to train the local tsunami center staff on the latest software and were there to see their modeling system at work firsthand.