A powerful 7.9-magnitude earthquake struck off the coast of Alaska early Tuesday, sparking tsunami warnings along the Pacific coasts of the US and Canada that were later called off.
The quake struck at 12:31 am (0931 GMT) in the Gulf of Alaska, 280 kilometers (175 miles) southeast of the town of Kodiak, the US Geological Survey said, revising a preliminary estimate of 8.2 magnitude.
The epicenter was 10 kilometers under the seabed.
The National Tsunami Warning Center did confirm a tsunami, meaning the water levels were slightly above normal.
Waves of less than one foot (30 centimeters) were detected in parts of southern Alaska, authorities said. As a precaution, officials in those areas encouraged residents to remain at higher ground.
But the monitoring center later canceled warnings and watches for coastal regions in Alaska, Canada's British Columbia and the US West Coast "because additional information and analysis have better defined the threat."
Heather Rand, who was 580 kilometers away in Anchorage, told CNN it felt like the longest earthquake she had ever experienced.
"It was a very long, slow build up. Creepy, more than anything. Definitely the longest, and I was born here," Rand said, adding the only damage was cracks in the wall.
So far, no quake damage or large waves have been reported in Kodiak, which is on an island off the coast, police spokesman Tim Putney told AFP.
"We are half an hour beyond the time we were told the first wave might hit. Nothing has happened," he said around 1115 GMT.
"We have people with their eyes on the sea, from a safe distance," Putney added.
USGS said that the quake occurred "as the result of strike slip faulting," explaining that it was in a location where two plates converged.
In the past century, 11 earthquakes of similar magnitudes have struck within 600 kilometers of Tuesday's earthquake, USGS said.