A 6.2-magnitude earthquake was recorded early Tuesday off the coast of eastern Japan, the U.S. Geological Survey said, but no tsunami advisory was posted.
The USGS said the quake at a depth of 6 miles struck about 60 miles east-northeast of Miyako and about 340 miles north-northeast of Tokyo.
There were no immediate reports of damage.
The quake was followed a half-hour later by a 5.1-magnitude tremor at a depth of more than 23 miles.
CNN reported no tsunami warning or advisory was issued either by the Japan Meteorological Agency or by the Pacific Tsunami Warning Center either.
Japan's northeast region, which includes Miyako, was devastated on March 11, 2011, by a deadly 9-magnitude earthquake and an accompanying monstrous tsunami, which together killed tens of thousands of people and set off a nuclear crisis at the Fukushima-Daiichi nuclear power plant.