The operator of the Fukushima nuclear plant has ordered workers near the coast to move to higher ground after a 7.6 magnitude earthquake, Japanese broadcaster NHK reported.
Japan's emergency agencies have declared a tsunami warning for the region that includes the crippled nuclear site.
All but two of Japan's 50 reactors have been offline since a magnitude-9.0 earthquake in March 2011 triggered a tsunami which led to massive radiation leaks at the plant 160 miles northeast of Tokyo.
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A 30-year-old man was arrested in Birmingham on Sunday on suspicion of preparing terrorist acts.