Authorities have urged people to evacuate low-lying coastal areas after a magnitude 7.9 earthquake struck the Gulf of Alaska, prompting fears of a tsunami.

The US National Weather Service sent an emergency alert to mobile phones in Alaska, warning: “Tsunami danger on the coast. Go to high ground or move inland.”

The powerful earthquake was recorded about 175 miles south east of Kodiak Island but was also felt hundreds of miles away in Anchorage.

The tsunami warning was issued across a large swathe of coastal Alaska and Canada’s British Columbia.

“If you are located in this coastal area, move inland to higher ground,” said Anchorage Office of Emergency Management. “Tsunami warnings mean that a tsunami with significant inundation is possible or is already occurring.”

In the town of Kodiak, emergency sirens sounded and officials warned residents to evacuate if they lived in low-lying areas.

Call handlers at the town’s police station were reported to be answering calls by saying: “If this about the tsunami, you need to get to get to higher ground immediately.”

Nathaniel Moore, who was on a fishing boat in Kodiak when the quake hit, said told CNN he felt it ”shake really good for a minute.” He and colleagues left the commercial vessel to head for higher ground following the tsunami warning.

“The whole town is evacuating,” he added.

The whole US West Coast was placed under tsunami watch, which means emergency officials and the public should prepare to take action. A tsunami watch was briefly in place for Hawaii before being cancelled.

“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.

The quake, initially measured at magnitude 8.2, hit around 160 miles south-east of Chiniak, Alaska at a depth of 15 miles at 12.30am local time (9.30am GMT).

There were no immediate reports of damage or injury.

Kodiak was projected to see the first wave at about 1.45am local time but there were no reports of any waves about two hours after the quake.

However, officials were telling people to hold fast at evacuation centre until further notice. The town has has several shelters above the 100-foot mark and police urged people below that level to evacuate.

Lieutenant Tim Putney, of the Kodiak Police Department, said he was woken from a deep sleep by 30 seconds of shaking.

“I’ve been Kodiak for 19 years that was the strongest, longest lasting one I’ve ever felt,” he said.

The Alaska Earthquake Information Centre said the quake was felt widely in several communities on the Kenai Peninsula and throughout southern Alaska. People reported on social media that the quake was felt hundreds of miles away, in Anchorage.