A POWERFUL magnitude 8.2 earthquake off northern Japan triggered tsunami warnings yesterday, sending thousands fleeing to higher ground but causing no reported injuries or damage.

Japan's Meteorological Agency immediately issued tsunami warnings, prompting an evacuation order for many coastal residents on the main northern island of Hokkaido. But the agency cancelled all tsunami advisories about nine hours after the earthquake.

Hokkaido lifted evacuation orders for 85,000 coastal residents in 22 towns as the fear of killer waves subsided, said state official Koji Urano.

The quake struck in the early afternoon near the Kuril Trench, about 310 miles east of the Etorofu island, the largest of a disputed four-island chain known as the Northern Territories in Japan and the Kuril Islands in Russia.

The Japanese agency initially estimated the magnitude as 8.3, but later reduced that to 8.2, the same strength recorded by the US Geological Survey. The quake struck 19 miles below the seabed, the agency said.

More than three hours after the quake, the largest wave, at 16 inches, hit Chichi-jima, an island of 2,000 people about 620 miles south of Tokyo. Small tidal swells were observed elsewhere, the agency said.

No injuries or damage were immediately reported from the offshore quake, said Hokkaido prefectural police spokesman Shinji Yamakoshi. He said he did not feel the quake at his headquarters in the island's western city of Sapporo.

Television footage showed one worried resident of Kushiro studying the coastline with binoculars from an evacuation centre. "I'm scared to return home," one woman, cradling a child, told NHK.

A tsunami warning was also issued for Alaska's western Aleutian islands, prompting some residents to flee. A tsunami watch issued for Hawaii was later cancelled.

The Philippine Institute of Volcanology and Seismology also issued a tsunami alert. Thousands of panicked villagers evacuated, but no giant wave came. In Japan, Hokkaido disaster prevention official Haruyuki Komachi said that thousands of residents had gathered at community centres following evacuation orders before they were allowed to go home.

Officials in one Hokkaido town, Abashiri, requested defence troops to bring the evacuees blankets and other relief goods, and police closed roads to the coast. Some train services were suspended.

The meteorological agency also issued warnings last November following a magnitude 7.9 quake in a similar area, but most areas saw waves of only about 7.8 inches high. In 1993, a quake off western Hokkaido triggered a large tsunami that flattened homes and killed more than 200 people.

The meteorological agency, which then came under fire for insufficient caution, has since begun issuing tsunami warnings even when only tiny waves are expected. Japan's heavily populated coastlines are now fitted with loudspeakers to order tsunami evacuations.

Tsunami waves - generated by earthquakes - are often barely noticeable in the ocean but can rise to great heights when they hit shore. A 9.1-magnitude earthquake off the coast of Indonesia on December 26, 2004, caused a tsunami that killed more than 230,000 people in 11 countries.

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