A tsunami warning was issued for Alaska's western Aleutian islands and a tsunami watch was issued for Hawaii after an 8.3-magnitude earthquake in the northern Pacific.
If waves reached Alaska, the West Coast and Alaska Tsunami Warning Center said, they could be expected to hit Dutch Harbor around 11:41 Alaska Standard Time on Saturday.
In Hawaii, waves could arrive about an hour later, the Pacific Tsunami Warning Center said.
The warning for the western Aleutians Islands was from the villages of Nikolski to Adak.
The center warned people in low-lying coastal areas to remain alert and to wait for instructions from local emergency officials.
Adak is a community of 167 about 2,000 kms southwest of Anchorage. Nikolski is a village of 31 about 1,400 kms southwest of Anchorage, Alaska.
The warning center issued a tsunami watch for the rest of the Aleutians and coastal areas along south-central Alaska to Seward.
Japan's Meteorological Agency issued tsunami warnings following the quake. The agency said waves as high as 3.3 feet (1 meter) could hit the northeastern coast of Japan's northern island of Hokkaido.
The tidal level fell 4 inches in Nemuro in northeastern Japan, a sign that a tsunami could hit later, the agency said.
Officials in towns along Japan's Pacific coast issued evacuation orders to flee to higher ground.
The quake struck about 500 kms east of the Etorofu islands between northern Japan and Russia, the agency said.