A strong earthquake with a preliminary magnitude of 6.5 on the Richter scale shook northeastern Japan on Monday, including Fukushima Prefecture, the Japan Meteorological Agency said.
There were no immediate reports of casualties from the 7:24 a.m. (2224 GMT Sunday) quake. The agency issued a warning for tsunami waves of up to 50 cm for the Pacific coast of Miyagi prefecture, which was already devastated by the March 11 earthquake and tsunami. The agency lifted the warning about 1.5 hours later.
The crippled Fukushima Daiichi nuclear power plant was not further damaged by Monday’s quake, the plant operator said. The Fukushima complex has continued to leak radioactive substances since it was hit by the magnitude 9.0-quake and ensuing tsunami on March 11.
The quake registered lower 5 on the Japanese seismic scale of 7 in central Miyagi Prefecture, about 340 km north of Tokyo.
The agency defines an intensity of lower 5 as strong enough to make hanging objects swing violently and most unstable ornaments fall.
The Japanese scale measures how much places were shaken on the surface while the Richter scale measures the energy of the quake itself. The focus of the tremor was off the northern Pacific waters off Ojika Peninsula, about 430 km north of Tokyo.
Northeastern Japan was severely damaged by the massive quake and tsunami that left almost 28,000 people dead or missing.
As of Monday, more than 60 aftershocks measuring 6 or higher on the Richter scale had been monitored in Japan since the March 11 earthquake and tsunami, the weather agency said, urging people to continue to be alert against powerful aftershocks.