Washington: A major earthquake of 7.4 magnitude hit in the Pacific Ocean on Thursday 107 miles (172 km) east of Atka, Alaska, at a depth of about 25 miles (40 km), and a tsunami warning was in effect for parts of coastal Alaska, warning agencies said.
A second quake of magnitude 7.2 hit in the same vicinity and at the same depth a half-minute later, the US Geological Survey said.
"A tsunami warning is now in effect which includes the coastal areas of Alaska from Unimak Pass, Alaska (80 miles northeast of Dutch Harbour) to Amchitka Pass, Alaska (125 miles west of Adak)," the West Coast and Alaska Tsunami Warning Centre said.
This leaves the coast of the entire Alaska peninsula and all of the Alaska mainland out of harm`s way.
The centre monitors tsunami risk only for the west coast of North America from the Mexican border to Alaska.
A tsunami warning means all coastal residents in the warning area who are near the beach or in low-lying regions should move immediately to higher ground and away from harbours and inlets, including those sheltered directly from the sea.
Earthquakes of this size magnitude are known to generate tsunamis. If a tsunami has been generated, the waves will first reach Adak, Alaska, at 8:12 pm Adak, Alaskam time (0412 GMT on Friday).