An earthquake of magnitude 8.2 was recorded off the Alaska Peninsula: the US Geophysical Institute (Usgs) reports.
The epicenter of the quake was located 91 km southeast of Perryville - a location about 800 km southeast of Anchorage, the largest city in the state - at a depth of 46.7 km.
The US National Weather Service has issued a tsunami warning for southern Alaska and the Alaska Peninsula itself.
The earthquake has been followed so far by a flurry of 21 aftershocks, including one - of magnitude 3.3 - with its epicenter in the Wide Bay, only a couple of kilometers from the coast and on the surface.