Monday's quake struck just before 5 p.m. local time (10 a.m. local time in Sweden) at a depth of ten kilometers in the sea about ten kilometers off Miyako in Iwate prefecture. Buildings were also reported to have shaken in Tokyo about 600 kilometers away, public broadcaster NHK reported.
An official from the Japan Meteorological Agency (JMA) warned in a televised press conference that more earthquakes, possibly even more powerful, could hit the area in the next two to three days.
"The probability of a new, huge earthquake occurring is relatively higher than normal," reads a statement from the JMA.
Shortly after the earthquake, tsunami warnings were issued for feared waves of up to three meters for the prefectures of Iwate, Aomori and Hokkaido.
"Immediately evacuate coastal and riverine areas to safer places," the JMA urged.
Those warnings have now been lifted in some areas, but remain in effect for Miyagi and Fukushima prefectures. According to the agency, tsunami waves have reached land in several places along the northeastern coast of Honshu and the coast of Hokkaido - although the waves were significantly smaller than feared.
Japan is one of the world's most seismically active countries.
