The US Geological Survey says the tremor measured 8.2

A tsunami warning has been issued for parts of Alaska and Canada after an earthquake.

The US Geological Survey says the tremor measuring 8.2 in magnitude was detected in the north Pacific.

A less serious tsunami watch has been issued for the entire American west coast.

Parts of Alaska and the west coast Canada have been issued with a tsunami warning and a tsunami watch is in place for the entirety of the the US west coast, including California and Oregon, part of Washington state and - initially - Hawaii, with "hazardous tsunami waves" said to be possible within the first three hours of the earthquake.

Among the major cities on tsunami watch are Anchorage and Juneau in Alaska, Canada's British Columbia and Vancouver, and Seattle, Portland, San Francisco, Los Angeles and San Diego in the US.

"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.

People in Anchorage have reported feeling the quake, despite being hundreds of miles away.

In a video posted to the Kodiak Police Department Facebook page, a Sergeant Beaver said: "This is not a drill - this is an actual tsunami warning. Everybody get at least 100ft above sea level. Everybody get out of your homes and to a safe place. Best place right now is the high school parking lot."

The department later said in a statement: "Remain at high ground. We have received two reports that the tide levels have been fluctuating in the channel six inches to one foot."