A 7.8-magnitude earthquake has struck off the Alaskan peninsula, triggering a brief tsunami warning for areas within 300km of the epicentre.
The shallow quake hit this morning about 500 miles southwest of Anchorage, and around 60 miles south-southeast of the remote settlement of Perryville, the US Geological Survey said.
"Based on the preliminary earthquake parameters... hazardous tsunami waves are possible for coasts located within 300km of the earthquake epicentre," the Pacific Tsunami Warning Centre said.
A tsunami warning for the Alaskan peninsula and south Alaska was later cancelled after only small waves were recorded.
Warning sirens sounded in Kodiak, the main city on Kodiak island, and several thousand people were evacuating lower lying areas, Sergeant Daniel Blizzard, with the Alaska State Troopers, told local media.
"People are pretty concerned especially with an earthquake that big that close to Kodiak," he said.
"The last one, there was no wave whatsoever. This time, we're not sure there is a wave, but we are preparing like there is one," Mr Blizzard said.
The first place predicted to see a tsunami wave, Sandy Point, had so far reported only "a very small wave", James Gridley, director of National Tsunami Warning Centre in Palmer, told Alaska Public Media (APM).
"We're not expecting a massive wave anywhere," he said.
The quake was felt hundreds of miles away.
"Bed and curtains were going. Felt like a very long quake!" one witness in Homer, Alaska, 400 miles from the epicentre, said on the quake monitoring website msc-csem.org.
Alaska is part of the seismically active Pacific Ring of Fire.
Alaska was hit by a 9.2-magnitude earthquake in March 1964, the strongest ever recorded in North America.
It devastated Anchorage and unleashed a tsunami that slammed the Gulf of Alaska, the US west coast, and Hawaii.
More than 250 people were killed by the quake and the tsunami.
