Beijing: An undersea quake measuring 6.1 on the Richter scale struck off the coast of Japan early Monday, the authorities here said.
The tremor occurred off Honshu coast around 4.30 am, the China Earthquake Networks Centre said.
The epicentre was at about 39.0 degrees north latitude and 142.1 degrees east longitude, and at a depth of 40 km, Xinhua reported.
However, the US Geological Survey put it at magnitude 6.4 and 115 km (72 miles) southeast of Morioka on Japan`s Pacific coast, and 31 km deep.
The quake was rated only 4 on Japan`s seven-point seismic scale, suggesting that no significant damage was expected, and no tsunami warning was issued.
(With Agency inputs)