Ten years ago, on a Friday afternoon in March, the most powerful earthquake ever recorded in Japan struck off the country’s eastern coast.
The 9.0-magnitude quake was so forceful it shifted the Earth off its axis. It triggered a tsunami which swept over the main island of Honshu, killing more than 18,000 people and wiping entire towns off the map.
At the Fukushima nuclear power plant, the gigantic wave surged over defences and flooded the reactors, sparking a major disaster. Authorities set up an exclusion zone which grew larger and larger as radiation leaked from the plant, forcing more than 150,000 people to evacuate from the area.
A decade later, that zone remains in place and many residents have not returned. Authorities believe it will take up to 40 years to finish the work, which has already cost Japan trillions of yen.
The Fukushima Daiichi Nuclear Power Plant is in the town of Okuma, in Fukushima Prefecture. It sits on the country’s east coast, about 220km (137 miles) north-east of the capital Tokyo.
On 11 March 2011 at 14:46 local time (05:46 GMT) the earthquake – known as the Great East Japan Earthquake, or the 2011 Tohoku earthquake – struck east of the city of Sendai, 97km north of the plant.
Residents had just 10 minutes warning before the tsunami hit the coast.
Overall almost half-a-million people were forced to leave their homes as a result of the earthquake, tsunami and nuclear accident.
What happened at Fukushima?
Systems at the nuclear plant detected the earthquake and automatically shut down the nuclear reactors. Emergency diesel generators turned on to keep coolant pumping around the cores, which remain incredibly hot even after reactions stop.
But soon after a wave over 14 metres (46ft) high hit Fukushima. The water overwhelmed the defensive sea wall, flooding the plant and knocking out the emergency generators.
Workers rushed to restore power, but in the days that followed the nuclear fuel in three of the reactors overheated and partly melted the cores – something known as a nuclear meltdown.
The plant also suffered a number of chemical explosions which badly damaged the buildings. Radioactive material began leaking into the atmosphere and the Pacific Ocean, prompting the evacuations and an ever-widening exclusion zone.
The Fukushima Disaster is classified as a level seven event by the International Atomic Energy Agency, the highest such event and only the second disaster to meet this classification after Chernobyl.
Critics blamed the lack of preparedness for the event, as well as a muddled response from both the plant operator Tokyo Electric Power (Tepco) and the government.
An independent investigation set up by Japan’s parliament concluded that Fukushima was “a profoundly man-made disaster”, blaming the energy company for failing to meet safety requirements or to plan for such an event. However, in 2019 a Japanese court cleared three former Tepco executives of negligence in what was the only criminal case to come out of the disaster.