The Japan Meteorological Agency said the earthquake had a preliminary magnitude of 7.3 and struck in the Pacific Ocean off the coast of Miyagi prefecture at 5:18 p.m. (0318 Eastern). The epicenter was 6.2 miles beneath the seabed.
After the quake, which caused buildings in Tokyo to sway for at least several minutes, authorities issued a warning that a tsunami potentially as high as 2.19 yards could hit. Ishinomaki, a city in Miyagi, reported that a tsunami of 1 yard hit at 6:02 p.m. (0402 Eastern).
The Pacific Tsunami Warning Center said there was no risk of a widespread tsunami, and subsequently dropped all tsunami warnings for the Japanese coast.
Miyagi prefectural police said there were no immediate reports of damage or injuries from the quake or tsunami, although traffic was being stopped in some places to check on roads.
Shortly before the earthquake struck, NHK television broke off regular programming to warn that a strong quake was due to hit. Afterward, the announcer repeatedly urged all near the coast to flee to higher ground.
Adam Ezard, a British expat living in Tokyo, tells CBSNews.com that Japanese media responded much more aggressively to the Friday quake than they had done in the past, with virtually all channels breaking into their regular programming, and NHK even giving information in multiple languages for the first time.
The response is an indication of how deeply the 2011 disaster affected the densely-populated island nation's psyche.
The magnitude-9.0 earthquake and ensuing tsunami that slammed into northeastern Japan on March 11, 2011, killed or left missing some 19,000 people, devastating much of the coast. All but two of Japan's nuclear plants were shut down for checks after the