The Nuclear Regulation Authority has launched an investigation of the seafloor off the coast of Fukushima Prefecture to check current contamination levels from the Fukushima No. 1 nuclear power plant meltdowns.

A Geiger counter will be trailed from a ship over about 1,000 sq. km. of the seafloor to help determine the density of radioactive cesium there.

While past studies have focused on certain points in the Pacific around the radiation-leaking Fukushima plant, the NRA's investigation aims to analyze more broadly how the contamination has spread on the seabed.