A powerful 7.4-magnitude earthquake hit northeastern Japan this morning, triggering tsunamis along the coast including a one-metre (3.3-foot) wave that crashed ashore at the stricken Fukushima nuclear power plant. National broadcaster NHK urged residents in the region to “flee immediately” to high ground, reminding listeners to heed the lessons of the “Great East Japan Earthquake”.A massive undersea quake that hit in March 2011 unleashed a tsunami that left more than 18,500 people dead or missing, and sent three reactors into meltdown at the Fukushima Daiichi power plant in one of the world’s worst nuclear disasters. The powerful quake also shook buildings in Tokyo, which lies about 230 kilometres to the south. Japan’s Meteorological Agency, which estimated the quake’s magnitude at 7.4, downgraded its tsunami warning from an “alert” to an “advisory” although still urged caution along coastal areas. An official from plant operator TEPCO told a news conference that a one-metre wave had hit the coast at the facility, but a spokesman for the company told AFP there were no reports of damage.