© USGS
A powerful 6.3-magnitude earthquake rocked Japan some 230km southeast of the country's capital, Tokyo, at a depth of 10km on Thursday night, the US Geological Survey (USGS) reported on its website.

Japan's Meteorological Agency reported that the earthquake "has caused no damage to Japan," while adding that "slight sea-level changes in coastal regions" may be observed.

No immediate tsunami warning has been issued.

Small tremors were reportedly felt in nine Japanese prefectures, including in Fukushima and Tokyo.



The epicenter of the quake lies in the Pacific Ocean some 150km (93 miles) from the city of Katsuura, located in the southern Chiba Prefecture.

Details to follow.