Houses damaged by the tsunami that, on 11 March 2011, swept across the coast of Northern Honshu killing over 15,000 people and destroying more than 300,000 houses. The seawater breached the defences at the Fukushima Daiichi nuclear power plant triggering the worst nuclear accident since Chernobyl. The plant was shut down and a 20 km evacuation zone around the plant was declared by the government. Levels of radiation in the evacuation zone remain high. By 2015 about 230,000 people remained in temporary housing.