The epicentre of the quake, which occurred at around 20:37 (UTC), was registered at a depth of 52.9 kilometres, south-east of Hachijo-jima, a volcanic island in the Philippine Sea, located about 287 kilometres south of the Japanese capital Tokyo.
No tsunami warning has been issued so far.
Japan is prone to earthquakes because of its geographical positioning. It's on the Ring of Fire, an arc of volcanoes and fault lines in the basin of the Pacific Ocean.
The country was previously hit by a strong earthquake measuring 6.3 on the Richter scale that struck off the coast of Honshu, the largest and most populous island of Japan, on July 28.
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