Japan earthquake early Thursday off the eastern coast was a magnitude 6.3. It's the second Japan earthquake in the past two days.
There were no immediate reports of damage or injuries.
A day earlier, a magnitude 7.3 earthquake off Japan's northeast coast shook buildings hundreds of miles (kilometers) away in Tokyo and triggering a small tsunami, but casued no significant damage or injuries.
The 4:44 a.m. Thursday (1844 GMT Wednesday) quake was shallow, some 1.2 miles (2 kilometers) below the surface, the USGS said.
The USGS said the quake hit some 126 miles (203 kilometers) east of Sendai, in Honshu, Japan, and about 272 miles (438 kilometers) northeast of Tokyo.
Japan lies on the "Ring of Fire" — an arc of earthquake and volcanic zones that stretches around the Pacific Rim and where about 90 percent of the world's quakes occur.