TOKYO, Feb. 28 (Xinhua) -- An earthquake with a preliminary magnitude of 5.6 struck off the coast of Fukushima Prefecture and rocked Japan's northeast on Tuesday, although no tsunami warning was issued by the weather agency, and nuclear plants in the region reported no abnormalities.
According to the Japan Meteorological Agency (JMA), the offshore temblor occurred at 4:49 p.m. local time, at a latitude of 37.5 degrees north and a longitude of 141.4 degrees east.
The quake originated at a depth of 50 km, the JMA said.
The quake registered lower 5 on Japan's seismic scale which peaks at 7, at four towns in Fukushima Prefecture and in Iwanuma City in Miyagi Prefecture, in the Tohoku region of northern Japan.
The JMA did not issue a tsunami warning or advisory as a result of the quake and nuclear operators in the areas rocked by the quake reported no abnormalities, including at the stricken Daiichi nuclear facility in Fukushima Prefecture.
In 2011, the nuclear complex in Fukushima was struck by a massive earthquake-triggered tsunami that knocked out the plant's key cooling functions, leading to multiple core meltdowns in its reactors.
The disaster, yet to be brought under control half a decade later, remains the worst nuclear calamity since Chernobyl in 1986, with which it shares a maximum level-7 rating on the global sliding scale of nuclear disasters
The adjacent Daiini complex in Fukushima was also said to be functioning with no abnormalities on Tuesday after the quake, according to its operator Tokyo Electric Power Company Holdings Inc. (TEPCO).
The Onagawa nuclear power plant in both the Oshika District and Ishinomaki city, in Miyagi Prefecture, was also unaffected by the tremor, its operator Tohoku Electric Power Company confirmed.
In other regions in Fukushima, Miyagi, Aomori and Iwate prefectures, in the northeast of the country, the quake registered between 1 and 4 on Japan's seismic intensity scale.
In the nation's capital of Tokyo, the temblor registered 2 in some locations and also made the scale in Niigata and Shizuoka prefectures.
The magnitude-5.6 quake was followed by a M4.6 quake at 5:08 p.m. local time, believed by the weather agency to be an aftershock.