A strong earthquake struck off the coast of Japan Wednesday, just 200 miles from a nuclear-power plant still reeling from a meltdown caused by a 2011 quake and tsunami.

The 6.1-magnitude temblor hit at about 1:37 a.m. local time, centered in the Pacific east of Fukushima, according to the US Geological Survey.

The Fukushima Daiichi nuclear power plant there suffered a triple meltdown in 2011 after a 9.0-magnitude quake 80 miles off the coast sent a wall of water careening into the facility and disabled its cooling system.

As of late Wednesday, neither Japanese nor US officials had issued a tsunami warning after the latest tremors.

Meanwhile, Japan is sending 70 relief workers to aid rescue efforts in quake-ravaged Mexico, according to the Japan Broadcasting Corp.