A strong earthquake with a preliminary magnitude of 6.0 jolted southern Japan on Tuesday, the Japan Meteorological Agency said. The quake, which struck at 10:33 p.m., was also felt in Tokyo.
There were no immediate reports of injuries or damage and no tsunami warning was issued.
The focus of the tremor was about 254 miles below the seabed in the Pacific Ocean off the southern coast of Japan's main island of Honshu, the agency said.
The magnitude of the earthquake was measured according to a technique similar to the Richter scale, but adjusted for Japan's geological characteristics.
Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.
In October 2004, an earthquake with a magnitude of 6.8 struck the Niigata region in northern Japan, killing 40 people and injuring more than 3,000. That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400.