The tremor was registered at 00:10 GMT, with the epicenter located 91 kilometers (56.5 miles) northwest of the small town of Sand Point, in the Aleutian Islands, at a depth of 35.2 kilometers.
There were no immediate reports of casualties or damage caused by the earthquake.
Alaska and the Aleutian Islands are located in a seismically active zone known as the Ring of Fire and regularly experience powerful earthquakes. On March 27, 1964, the 9.2 magnitude Great Alaskan earthquake devastated a number of settlements, including the state's biggest city of Anchorage, killing 131 people.