A powerful earthquake of magnitude 7.8 which hit between Russia and Alaska is expected to cause tsunami waves, the US Pacific Tsunami Warning Centre says.
The quake struck in the northern Pacific Ocean between the tip of the Aleutian Islands and Russia's Kamchatka, according to the US Geological Survey which initially recorded it as 7.7.
The earthquake struck at 1.34am on Tuesday local time some 200 kilometres from the city of Nikol'skoye on Bering island off the Kamchatka Peninsula.
The epicentre was west of Attu, the westernmost and largest island in the Near Islands group of Alaska's remote Aleutian Islands.
The earthquake was very shallow - only 10 km below the seabed, which would have amplified its effect, but it was quite far from any mainland.
The US Pacific Tsunami Warning Centre said "hazardous tsunami waves are possible for coasts located within 300 km of the earthquake epicentre."
Tsunami waves, however, were unlikely to reach Kamchatka's eastern coast, some 500 km.
The quake was followed by several aftershocks, including a couple above magnitude 5.0.