A TSUNAMI alert has been issued for parts of Alaska, Canada and the entire US west coast.
The warning comes after a 7.9-magnitude earthquake was recorded off the southern coast of Alaska.
The quake struck some 281km south-east of Kodiak at a depth of 9.6km at 09:31 GMT (00:31 local time).
Tue Jan 23 10:07:47 UTC 2018 event picture pic.twitter.com/qeKKqFTysB
— NWS Tsunami Alerts (@NWS_NTWC) January 23, 2018
A buoy has reportedly recorded a wave of 10m (32ft) just north-east of the epicentre.
The US Geological Survey initially rated the earthquake as an 8.2 on the Richter Scale but has since downgraded the figure to 7.9.
The NWS Pacific Tsunami Warning Center said that "widespread hazardous tsunami waves" are possible along some coasts within the next three hours.
Southeast and south Alaska, Alaska peninsula, Aleutian Islands and British Columbia in Canada are all under a 'tsunami warning', while California, Oregon and Washington in the US are under the slightly less severe 'tsunami watch' alert.
Red showing vertical displacement of water at time of earthquake at Buoy 46409 in the Gulf of Alaska. Tsunami WARNING in place for Alaskan coast from Aleutians to panhandle and all of the west coast of Canada. Tsunami Watch for US West Coast and Hawaii. pic.twitter.com/ZX3i3rz0YN
— Ed Russo (@EdRussoWSBT) January 23, 2018
The Anchorage Office of Emergency Management in Alaska 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."
A number of people reported on The Irish Post's Facebook page that the quake was felt in Anchorage, hundreds of miles away from its epicentre.
Megan Clarke wrote: "Yep I'm in Anchorage Alaska and my whole house and everything in it wouldn't stop shaking for like a whole minute!"
While Pamela Priest added: "Woke me up in Anchorage, Alaska! That was one really long shake. My heart is still pounding!"
— Amichai Stein (@AmichaiStein1) January 23, 2018