|Japan lies on the 'Ring of Fire' where about 90 per cent of the world's quakes occur [EPA]
A major 7.2-magnitude quake has hit Japan, swaying buildings in Tokyo and triggering a tsunami warning, but causing no reported casualties or damage.
The quake struck late on Wednesday morning, about 10km below the Pacific seafloor. The epicentre was about 160km offshore and 430km northeast of Tokyo.
The Japan meteorological agency issued a tsunami warning for the east coast of the main Honshu island, where a 24-inch wave was first reported at Ofunato port half an hour after the quake.
Police said they had received no reports of casualties from the quake, or from a 5.6-magnitude aftershock that struck nearby about 12 minutes later.
Tokyo Electric and Tohoku Electric, nuclear power operators, confirmed that the quake did not damage their atomic plants and prefectures in Aomori, Miyagi and Fukushima."
"First I felt a jolt that pushed from underneath, then a big sideways tremor that lasted for about 20 seconds," Yoshiyuki Sato, an official at Kurihara City in Miyagi prefecture, about 300km northeast of Tokyo, told the Reuters news agency.
Some Shinkansen bullet trains in the region automatically stopped when the quake hit but then resumed their services, railway operators said.
Local residents in the rural seaside areas where the quake was felt most strongly reported no immediate damage from the quake.
"It continued for about 30 seconds, but I don't see anything that looks different," Yoshio Hoshi, a retired fisherman in Miyagi prefecture, said.
Japan lies on the 'Ring of Fire'- an arc of earthquake and volcanic zones that stretches around the Pacific Rim and where about 90 per cent of the world's quakes occur.