Hawaii orders evacuations in Pacific tsunami threat

* Tsunami could wash over some Pacific islands - Red Cross

* Warning extended to Northern California and Oregon (Updates tsunami warning)

By Suzanne Roig and Jorene Barut

HONOLULU, March 10 (Reuters) - Hawaii ordered evacuations of its coastal areas and braced for a possible tidal wave set off by Friday's earthquake in Japan as a tsunami warning was extended to most of the Pacific basin, including northern California and Oregon.

Some 3,800 miles (6,200 km) from Japan, the main airports on at least three of the major Hawaiian islands -- Maui, Kauai and the Big Island of Hawaii -- were shut down as a precaution, and the U.S. Navy ordered all warships in Pearl Harbor to remain in port to support rescue missions as needed.

Civil defense officials ordered all Hawaiian coastal areas evacuated by 2 a.m. local time, about an hour before the first wave was expected to hit the islands at 8 a.m. EST/1300 GMT.

Authorities also ordered evacuations from low-lying areas on the U.S. island territory of Guam in the western Pacific, where residents there were urged to move at least 50 feet (15 metres) above sea level and 100 feet (30 metres) inland.

Guam initially appeared to have emerged unscathed.

"So far no waves," Lorilee Crisostomo told Reuters by telephone from Guam, roughly an hour after the tsunami was first due. Two hours later, Guam Police Department Officer A.J. Alajadia said there was still no sign of trouble.

The Pacific Tsunami Warning Center reported a tsunami more than 5 feet (1.5 metres) above sea level on the Midway Atoll between Japan and Hawaii, but there were no reports of damage.

The agency said the tsunami warning was posted from Mexico down the Pacific coast of South America. The advisory was later extended to a stretch of the U.S. West Coast from Point Conception, California, north through Oregon.

President Barack Obama, a native of Hawaii, was notified of the massive Japanese quake at 4 a.m./0900 GMT and instructed the Federal Emergency Management Agency to be prepared to affected U.S. states and territories, the White House said.

"We will continue to closely monitor tsunamis around Japan and the Pacific going forward, and we are asking all our citizens in the affected region to listen to their state and local officials," Obama said in a statement.

The quake off Japan's northeast coast was the biggest in 140 years and triggered tsunami waves of up to 30 feet (10 metres) that swept across farmland, carrying away homes, crops, vehicles and triggering fires. [ID:nL3E7EB0MF]

On Easter Island, a Chilean territory in the South Pacific, authorities planned to move residents to higher ground hours before a possible tsunami was expected to reach the volcanic isle on Friday afternoon.