The earthquake took place at approximately 12:37 local time (2037 GMT), with its epicenter located about 54 miles (87 kilometers) south of the island town of Sand Point, USGS said. The epicenter had a relatively shallow depth of 20.1 kilometers.

Authorities issued a tsunami warning for South Alaska and the Alaska peninsula after the quake.

"A tsunami has been confirmed and some impacts are expected," said the National Tsunami Warning Center in Palmer, Alaska.

The warning was issued for "South Alaska And the Alaska Peninsula, Pacific coasts from Kennedy Entrance, Alaska (40 miles SW of Homer) to Unimak Pass, Alaska (80 miles NE of Unalaska)," the center said.

Based on initial information, tsunami warnings were not issued for areas further afield, the NTWC said.

Alaska is part of the seismically active Pacific Ring of Fire.

The remote state was hit by a 9.2-magnitude earthquake in March 1964, the strongest ever recorded in North America.

It devastated the city of 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.

A 7.2-magnitude quake hit off the Alaskan peninsula in July 2023, with no major damage reported following the tremor.