A 7.9 magnitude earthquake struck off Alaska's Kodiak Island early today, prompting a tsunami warning for a large swath of the state's coast and sending some residents fleeing to higher ground.
Officials at the National Tsunami Center cancelled the warning after a few tense hours after waves failed to show up in coastal Alaska communities.
Alaska's Division of Homeland Security and Emergency Management said there have been no reports of damage, so far.
The strong earthquake hit at 12:30 a.m. (local time) and was recorded about 170 miles southeast of Kodiak Island in the Gulf of Alaska.
Revised (8.2 -> 7.9): 7.9 earthquake, 280km SE of Kodiak, Alaska. 2018-01-22 23:31:40 at epicenter (46m ago, depth 10km). https://t.co/VqDNNMApR0— Earthquakes Tsunamis (@NewEarthquake) January 23, 2018
Kodiak Island is located about 200 miles southwest of Anchorage, Alaska's largest city, which was not under a tsunami threat.
Reports varied about how long the shaking lasted. In the popular cruise ship town of Seward, about 230 miles northeast of Kodiak Island, fire chief Eddie Athey said the quake felt like a gentle rattle and lasted for up to 90 seconds.
"It went on long enough that you start thinking to yourself, 'Boy, I hope this stops soon because it's just getting worse,'" Athey said.
Initially, the USGS said the earthquake was a magnitude 8.2. That prompted the tsunami warning for coastal Alaska and Canada's British Columbia, while the remainder of the US West Coast was under a watch.
An advisory remained in effect for a small part of the state. Watches were canceled for Washington, Oregon, California and Hawaii. Officials in Japan also said there was no tsunami threat there.
Warnings from the National Weather Service sent to cellphones in Alaska warned: "Emergency Alert. Tsunami danger on the coast. Go to high ground or move inland."
Kodiak officials warned residents to evacuate if they lived in low-lying areas. Residents scrambled to safety, and some sought refuge in schools that were transformed into shelters.
BREAKING: Magnitude 8.2 earthquake strikes 175 miles southeast of Kodiak, Alaska; tsunami warning issued.— The Associated Press (@AP) January 23, 2018
The city of Kodiak was projected to see the first wave about an hour after the quake, but 90 minutes after the quake, there was no report of any waves.
Lt. Tim Putney of the Kodiak Police Department said: "We haven't seen anything yet or had any reports of a wave."
However, officials told people to hold fast at evacuation centers until further notice. He said the town has several shelters above the 100-foot mark, and they were still encouraging people below that level to evacuate.
The earthquake woke Putney out of a dead sleep, and he estimates it shook for at least 30 seconds.
"I've been Kodiak for 19 years that was the strongest, longest lasting one I've ever felt," he said by telephone. Alaska Gov. Bill Walker said on his Twitter feed that he has been in contact with local officials and the state's adjutant general, and he urged residents to heed any warnings to move inland or to higher ground.
Alaska, northwest of Canada, is the largest and most sparsely populated US state. It's known for its diverse terrain of open spaces, mountains and forests, with abundant wildlife and many small towns.