A powerful earthquake measuring magnitude 6.7 has struck off the coast of the Japanese region of Miyagi, north of Tokyo , prompting the government to issue emergency warnings to people in five prefectures. The Japanese authorities rated Friday’s earthquake a five on its 1-7 intensity scale, but said there was no immediate risk of a tsunami. A high speed railway line between Tokyo and Shin-Aomori stations was suspended following the quake, according to operator JR East, but there has been no immediate reports of injuries or damage, according to reports in the Japan Times. Locator map of where the powerful 6.7-magnitude earthquake struck in Japan's Miyagi prefecture (outlined) (The Independent) The focus of the 8.22pm (local time) quake was off the coast of Miyagi prefecture. The US Geological Survey said the earthquake’s epicentre was 50km east of the town of city of Ofunato and at a relatively large depth of around 43km. The USGS revised the magnitude of the quake from 6.6 to 6.7.…