A strong earthquake struck off the coast of northern Japan for a third consecutive day early Sunday though there were no immediate reports of people injured or damage. The shallow 6.0 magnitude quake hit at 00:58 am (1558 GMT Saturday) 170 kilometres (105 miles) east-northeast of Miyako city, the US Geological Survey said. It was followed by a 5.3 aftershock. There was no threat of a tsunami following the quake, said the Japan Meteorological Agency.