Japanese authorities have issued a 'megaquake' warning after a powerful 7.5 magnitude tremor struck off northern Japan on December 8, injuring 23 people and triggering a tsunami in Pacific coast communities. The meteorological agency issued a caution about possible aftershocks in the coming days. It said there is a slight increase in risk of a magnitude 8-level quake and possible tsunami occurring along Japan's northeastern coast from Chiba, just east of Tokyo, to Hokkaido. Find out more at Daily Mail. #earthquake #japan #quake #tsunami