• Quake magnitude 7.9. initially measured at 8.2
• Get to higher ground,' residents on Alaskan island told
• Hawaii no longer seen at risk of tsunami

ANCHORAGE: A magnitude 7.9 earthquake hit the Gulf of Alaska in the early hours of Tuesday, prompting warnings of a possible tsunami down the west coast of North America.

Emergency sirens sounded in Kodiak, a town of 6,100 people on Alaska's Kodiak Island, one of the closest settlements to the epicenter.

"This is a tsunami warning. This is not a drill. Please get out to higher ground," said the announcer on local public radio station KMXT. "If you are on the flats, get up on one of the hills ... Just go high."

There were no immediate reports of damage or injury.

The quake, initially measured at magnitude 8.2, hit around 250 km (160 miles) southeast of Chiniak, Alaska at a depth of 25 km at 12:31 a.m. (0931 GMT), the U.S. Geological Survey said.

"If you are located in this coastal area, move inland to higher ground. Tsunami warnings mean that a tsunami with significant inundation is possible or is already occurring," the Anchorage Office of Emergency Management said in a warning for Alaska and British Columbia.

A tsunami watch for the entire U.S. west coast was issued.

"Based on all available data a tsunami may have been generated by this earthquake that could be destructive on coastal areas even far from the epicenter," the Pacific Tsunami Warning Center said.

An initial tsunami watch for Hawaii was canceled.

Japan's meteorological agency said it was monitoring the situation but did not issue a tsunami alert.