A catastrophic tidal surge failed to materialize following the powerful earthquake that struck Chile on Saturday, leaving experts to defend the dire warning they issued for Pacific nations.
After the Chilean coast was racked by a violent magnitude-8.8 quake, oceanographers released a bulletin warning Pacific islands such as Hawaii that "urgent action should be taken to protect lives and property," from a pending tsunami.
When devastating waves failed to strike, authorities lifted the warning, which affected more than 50 countries and territories. Low-level advisories had been in effect as far north as Alaska and the coast of British Columbia.
Scientists admitted they overplayed the threat, but defended their actions, saying they had learned from the 2004 tsunami in the Indian Ocean that killed 230,000 people.
"Failure to warn is not an option for us," said Dai Lin Wang, an oceanographer at the Pacific Tsunami Warning Center in Hawaii. "We cannot have a situation that we thought was no problem and then it's devastating. That just cannot happen."
"If you give too many warnings and none of them materialize, then you lose your credibility," Wang added. "That's something that we have to deal with and we have to improve."
At least five people died following the quake after a tsunami struck Robinson Crusoe Island, off the Chilean coast. Enormous waves also caused major damage in the Chilean port city of Talcahuano.
Chiles' navy erred by not issuing a tsunami warning immediately after the powerful quake, said Francisco Vidal, the country's defence minister. But he added that port captains sounded alarms that may have saved thousands of lives in coastal communities.
The effects of tidal waves were minor in other regions of the Pacific Rim.
The largest wave to hit Japan struck the northern island of Hokkaido. Some piers briefly flooded, but there were no immediate reports of damage caused by the 1.2-metre wave.
Hundreds of thousands of Japanese residents headed to higher ground from low-lying coastal areas. But the waves that hit there -- and in the other 52 nations and territories under a tsunami warning Saturday -- were smaller than expected.
In the northern Japanese city of Kesennuma, streets near the coast were flooded with seawater for about four hours before the water receded. There was little impact on local residents.
The hours of lead time between the earthquake and when experts predicted the first tsunami waves would arrive allowed them to warn residents in advance.
Hawaiians woke to the blare of warning sirens Saturday, and many lined up for gas in preparation of what might have been. By the time the waves hit the U.S. state Saturday, 16 hours after the earthquake, they were smaller than expected and caused no apparent damage.
"We expected the waves to be bigger in Hawaii, maybe about 50 per cent bigger than they actually were," Gerard Fryer, a geophysicist for the Pacific Tsunami Warning Center, told The Associated Press. "We will be looking at that."
Pacific nations removed their local advisories as smaller waves than predicted hit their shores.
But New Zealand's Ministry of Civil Defence and Emergency Management will keep its tsunami advisory -- the lowest level of warning -- until 8 a.m. local time Monday.
Warnings also remained in place Monday morning across much of Japan's Pacific coast.
Earlier Sunday, New Zealand officials reported a wave measuring about two metres on the Chatham Islands.
Several hundred residents of North Island coastal cities Gisborne and Napier were instructed to leave their homes, while residents on South Island's Banks Peninsula were told to be ready to leave at any time.
With files from The Associated Press
