Japan is preparing to mark the sixth anniversary of the massive earthquake, tsunami and nuclear disaster that devastated swathes of the country.

At 2.46pm on 11 March 2011, Japan was struck by an earthquake with a magnitude of 9.0 – the biggest in the nation's recorded history and one of the five most powerful recorded ever around the world. The epicentre was located about 70km east of Tohoku in Miyagi prefecture, north-eastern Japan. The six-minute-long tremor and its thousands of aftershocks shook buildings across much of northern Japan and the nation's capital.

The energy released by the earthquake produced a huge tsunami. Within an hour of the earthquake, towns lining the shore were flattened by the massive waves. Waves towering four-to-five-metres-high crashed through homes and fields, and engulfed fleeing vehicles. In Iwate prefecture's Miyako city, the tsunami reached as high as 40 metres.

The tsunami killed more than 15,000 people. More than 65% of casualties were elderly men and women who were not able to run to higher ground or swim to safety.

Japan tsunami
13 March 2011: A victim's hand sticks out from the rubble in Rikuzentakata Toru Hanai/Reuters

The tsunami also led to a nuclear disaster when the Fukushima Daiichi power plant was inundated by waves, causing a cooling system failure, followed by a nuclear reactor meltdown and the release of radioactive materials. Tens of thousands of people were forced to evacuate an area 20km radius around the reactor. The plant's owners, Tokyo Electric Power Company (Tepco) said 45 metric tons of radioactive water were released into the ocean.

Six years on, the operator continues the struggle of decommissioning the crippled reactors, which is likely to take decades and cost tens of billions of pounds.

At the latest count, 15,894 people were killed by the earthquake and tsunami, and 2,562 are still not accounted for across 12 prefectures.

Japan tsunami
15 March 2011: Members of Japan's Self Defence Force walk past the covered body of a woman in Rikuzentakata, Iwate prefecture
Japan tsunami
16 March 2011: A woman cries as she holds the hand of her dead mother who was buried in the mud in Rikuzentakata City, Iwate Prefecture Kyodo/Reuters

According to the World Bank, the economic cost of the disaster tallied up to $235 billion (£192bn), making it the most expensive disaster in world history. Japan's then-prime minister, Naoto Kan, called the 11 March 2011 disaster the toughest crisis to hit Japan since the end of World War Two.