A powerful earthquake struck off north-eastern Japan on March 11, 2011, triggering a tsunami that knocked out the cooling system at the Fukushima Daiichi Nuclear Power Station, prompting explosions and meltdowns.
The following are some of the key figures on the disaster:
The earthquake was recorded at a magnitude of 9.0, the most powerful ever in Japan.
The tsunami reached 30 metres in places and flattened more than 260 coastal towns and cities.
The confirmed death toll from the flooding was 15,894 people with another 2,562 still missing, officials said.
The number of homes that collapsed, completely or partially, was put at 400,243. A total of 740,014 other private houses sustained damage from flooding, fire and other impacts, according to the official tally.
The immediate damage was estimated at 210 billion dollars, according to reinsurer Munich Re.
More than 100,000 people were evacuated from their homes in the region to avoid radioactive contamination.
The operator Tokyo Electric said it could be 30 to 40 years before the power plant is fully decommissioned.
Around 7,000 workers are deployed each day to the disaster zone in Fukushima.
Some 75,000 tons of contaminated water is being held in tanks on the premises.