There were no immediate reports of damage or injuries, but the Japan Meteorological Agency announced that a tsunami of up to 1.6 feet (a half meter) may wash into Miyagi Prefecture.
The tsunami alert was localized to Japan. The U.S. Pacific Tsunami Warning Center said no wave was expected in Hawaii or on the U.S. west coast.
The alert was prompted by a quake that the U.S. Geological Survey measured at 7:23 a.m. Monday Japan time near the east coast of Honshu.
The USGS said the quake was 3.7 miles (5.9 kilometers) deep.
A magnitude-9 quake off Japan's northeast coast on March 11 triggered a tsunami that barreled onshore, triggering a humanitarian disaster that is thought to have killed about 18,000 people.