Tokyo (CNN) -- A powerful earthquake struck Japan on Thursday, triggering a tsunami warning for one prefecture and advisories in other prefectures.
The Japan Meteorological Agency said the quake was a magnitude of 7.4. The U.S. Geological Survey said it was 7.1.
There were no reports of casualties from anywhere in the earthquake zone, the National Police Agency said.
Workers evacuated the Fukushima Daiichi nuclear plant following the quake, the Tokyo Electric Power Company said. Tokyo Electric said it has communication with the plant and the power is still on there. There were no immediate reports of damage, it said.
The quake's epicenter was off the coast of Miyagi in northeastern Japan, the Japan Meteorological Agency said.Witness: Aftershocks are 'gut-wrenchinThe U.S. Geological Survey said the quake was centered 41 miles (66 kilometers) from Sendai -- one of the areas worst hit by last month's 9.0-magnitude quake -- and 73 miles (118 kilometers) from Fukushima, where a crisis has been under way at the nuclear plant since last month's tsunami.
Public broadcaster NHK reported a tsunami warning for Miyagi prefecture, saying people in that area should evacuate away from the shore to a safe place.
NHK also reported tsunami advisories for the Pacific coast of Aomori Prefecture, and for the Iwate, Fukushima, and Ibaraki Prefectures.
The Pacific Tsunami Warning Center said based on all available data, "a destructive Pacific-wide tsunami is not expected and there is not a tsunami threat to Hawaii."
The quake was centered 207 miles (333 kilometers) from Tokyo, the U.S. Geological Survey said.
It was 15.9 miles (25.6 kilometers) deep, the agency reported.
It took place shortly after 11:30 p.m. local time (10:30 a.m. ET).