The quake occurred at a depth of 117 miles (212 km) some 19 miles south-southwest of the uninhabited island of Agrihan in the U.S. territory, the U.S. Geological Survey said.
No tsunami warning has been issued, according to the National Tsunami Warning Center.
Spokesman Paul Whitmore said a barely noticeable wave of about two inches was recorded in Saipan, the largest of the islands.
