Tokyo: A 7.8-magnitude earthquake struck off the Japanese coast Saturday, geologists said, shaking buildings in Tokyo and setting off car alarms, an AFP correspondent reported.
Despite the huge power of the quake, there was no risk of a tsunami, The Pacific Tsunami Warning Centre reported.
Residential buildings swayed for around a minute as the quake built in intensity at around 8.30pm (1130 GMT).
There were no immediate reports of injuries or damage.
The epicentre was 676 kilometres (422 miles) below the Earth´s surface. It was centred on a remote spot in the Pacific Ocean around 870 kilometres south of Tokyo, the US Geological Survey said.