A strong 6.2-magnitude quake struck off northern Japan on Tuesday, US seismologists said, but there were no immediate reports of damage and no tsunami alert was issued.

It hit at 7.21am (2221 GMT Monday) in waters 96 kilometres (60 miles) east of Miyako on the main island of Honshu at a depth of just 9.7 kilometres, according to the US Geological Survey.

The quake was followed by a 5.1-magnitude jolt roughly 30 minutes later, which hit 107 kilometres east of Miyako. It was measured at a depth of 37.9 kilometres, the USGS said.

The area, badly damaged by the major earthquake and tsunami of March 2011, is located roughly 500 kilometres north of Tokyo.

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