Associated Press, NDTV: Updated: July 10, 2011 09:32 IST.
Residents in coastal areas were warned to evacuate for about two hours after the quake, but there were no immediate reports of damage.
The quake hit at 9:57 local time (0057 GMT), and a warning of a tsunami was issued for most of the northeastern coastline. The epicenter of the quake was in the Pacific Ocean off the coast of Japan's main island, Honshu, at a depth of about 20 miles (30 kilometers).
Japanese officials predicted the quake could generate tsunami of up to 20 inches (50 centimeters), but the initial waves were only about 4 inches (10 centimeters). The tsunami warning was lifted after the forecast arrival time of the waves passed in most areas without any tsunami being recorded.
Japan's Meteorological agency at first estimated the strength of the quake at 7.1, but later revised that to 7.3. It also revised the depth estimate from 10 to 30 kilometers.