Japan was struck by a powerful 7.4 magnitude earthquake, triggering a brief tsunami warning, which was later withdrawn. The country's meteorological agency said that the tremor that struck in the early hours of Tuesday (22 November) was centered off the coast of Fukushima Prefecture at a depth of 10km.

The agency added that the tremblor was an aftershock of the March 2011 (9.0 magnitude) earthquake that had led to large scale destruction in the country.

On Tuesday, the initial tsunami warnings were downgraded to advisories, which were issued for other prefectures along the Pacific Ocean. Abnormal waves were observed in some parts, although no casualties have been reported so far.

The Fukushima power plant, where more than 2,500 nuclear fuel rods are currently stored, has been shut down. The cooling system in one of the reactors was briefly knocked out because of the tremor, but it was later restored, said Tokyo Electric Power Company (Tepco). "We have been informed that there is no immediate risk of radiation leaks or rise in the temperatures [of the cooling pool]," Chief Cabinet Secretary Yoshihide Suga told reporters shortly after the quake. However, the US Geological Survey noted that the quake was measured at 6.9.

State broadcaster NHK repeatedly issued warnings to residents in coastal areas to move to higher ground. "Please move as far away from the shoreline as possible. Please remember the Great East Japan earthquake," news anchors warned.

Prime Minister Shinzo Abe, who is currently in Peru for the Apec summit said: "From my side, to the nation, we asked that proper and accurate information over the tsunami and the evacuation should be issued, and also to grasp and understand the condition of the damage as quickly as possible, and also to take proper emergency measures. I called the chief cabinet secretary directly."

Japan earthquake
Firefighters and local residents look towards a port to check the water level after tsunami advisories were issued following an earthquake in Soma, Fukushima prefecture, Japan Kyodo via Reuters