7.9 quake off Alaska sparks tsunami fear

A 7.9-magnitude earthquake has struck near the coast of Alaska with a tsunami warning in place.

A magnitude 7.9 earthquake has hit the Gulf of Alaska, 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 epicentre.

"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."

The quake, initially measured at magnitude 8.2, hit around 250km southeast of Chiniak, Alaska at a depth of 25km, the US 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.

Residents of British Columbia's island community of Tofino were seen gathering at a community centre, in pictures posted on the website of broadcaster CBC.

However, some two hours after the quake struck there were no reports of tsunami waves hitting Alaska or Canada.

A tsunami watch for the entire US 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 epicentre," the Pacific Tsunami Warning Centre said.

An initial tsunami watch for Hawaii was cancelled.

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