Disaster response robot being tested in Fukushima Prefecture, Japan. Fukushima was the site of the Daiichi nuclear power plant disaster. The disaster, on 11th March 2011, was triggered after a magnitude 9.0 earthquake occurred 130 kilometres off the east coast of Japan causing a devastating tsunami. The tsunami damaged the Fukushima Daiichi nuclear power station, leading to the meltdown of three of the nuclear reactors and a leak of radioactive material. It was one of the world's largest nuclear incidents since the Chernobyl disaster of April 1986.