A 6.8-magnitude earthquake struck off Japan's northeastern coast on Saturday but no tsunami warning was issued, Japanese and US authorities said. The United States Geological Survey said the quake hit at 10:27 am (0127 GMT) at a depth of 47 kilometres (29 miles) in the Pacific, off Ishinomaki, Miyagi prefecture -- near the epicentre of a huge 2011 quake which triggered a towering tsunami, killing more than 18,000 people. si/kaf/rma