Survivors gathered along Japan's north-east coast to remember the thousands of lives that were lost in the tsunami four years ago.

Japan tsunami anniversary
Candles are placed to form the date of the March 11, 2011 earthquake and tsunami disaster during a memorial event to mourn the victims of the disaster in Ishinomaki, Miyagi prefectureKyodo/Reuters
Japan tsunami anniversary
A man touches the name of a fellow fisherman killed by the March 11, 2011 earthquake and tsunami, at a cenotaph in Wakabayashi district, Sendai, Miyagi prefectureKyodo/Reuters
Japan tsunami anniversary
Pupils sit in an almost empty classroom at Kawauchi Elementary School in Kawauchi, Fukushima. The school had 114 students before the disaster, now the number is 29 even after the evacuation orders were lifted for the eastern area of the villageKen Ishii/Getty Images
Japan tsunami anniversary
People observe a moment of silence near a tsunami-devastated disaster prevention office building in Minamisanriku town, Miyagi prefectureKyodo/Reuters
Japan tsunami anniversary
People look at paper lanterns during a memorial service for tsunami victims at the Yuriage Junior High School in NatoriChris McGrath/Getty Images
Japan tsunami anniversary
Balloons in the shape of doves are released into the air during a memorial service at the former Yuriage junior high school in Natori, Miyagi PrefectureKazuhiro Nogi/AFP

On 11 March 2011, Japan was shaken by an earthquake with a magnitude of 9.0, the biggest in the nation's recorded history and one of the five most powerful ever recorded around the world.

The latest numbers from Japan's police department show 15,891 people have been confirmed dead, with 2,584 still unaccounted for.

Japan tsunami anniversary
Members of Japanese Coast Guard and policemen search at the seashore in Shichigahama town, Miyagi prefecture, in the hope of finding missing bodiesKazuhiro Nogi/AFP
Japan tsunami anniversary
A woman takes a photo of the "miracle tree" in Rikuzentakata, a replica of a lone pine tree that survived the 2011 earthquake and tsunamiChris McGrath/Getty Images

Some 229,000 people remain evacuated from their homes, with about 90,000 living in temporary housing. Of the total, more than half come from areas affected by the Fukushima Daiichi nuclear plant meltdowns.

At a solemn ceremony in Tokyo, Emperor Akihito said he still recalls the "unforgettable, horrifying" footage of the tsunami on television four years ago and that he shares the pain of those still without prospect of returning home because of the radiation in Fukushima.

"When I think of the people who are still unable to return to their homes, it hurts my heart," Akihito said.

Japan tsunami anniversary
Japan's Prime Minister Shinzo Abe bows to Emperor Akihito and Empress Michiko during the national memorial service for the victims of the March 11, 2011 earthquake and tsunami, in TokyoToru Hanai/Reuters

The operator of the crippled Fukushima Daiichi nuclear plant held a moment of silence to commemorate the victims of tsunami and nuclear accident four years ago.

Three of the plant's six reactors suffered core meltdowns after the tsunami struck, triggering the world's worst nuclear disaster since Chernobyl in 1986.

Japan tsunami anniversary
Employees of Tokyo Electric Power Co (Tepco), the operator of the tsunami-crippled Fukushima Daiichi nuclear plant, take part in a moment of silence at the company's headquarters in TokyoYuya Shino/Reuters
Japan tsunami anniversary
Police officers offer chrysanthemums during a memorial ceremony at Namie, near Tepco's Fukushima Daiichi nuclear plant in Fukushima prefectureYoshikazu Tsuno/AFP

While Tepco employees were holding the tsunami commemoration, about a hundred people marched on streets of Tokyo to protest against the government-owned utility's handling of the nuclear crisis.

The decontamination and decommissioning of Fukushima Daiichi is expected to take up to 30 years and cost billions of dollars.

Japan tsunami anniversary
An aerial view of the tsunami-crippled Fukushima Daiichi nuclear power plant in Fukushima prefecture, with hundreds of tanks of radiation-contaminated waterKyodo/Reuters
Japan tsunami anniversary
An aerial view shows (front to rear) reactor buildings numbers 1, 2, 3 and 4 at Tepco's tsunami-crippled Fukushima Daiichi nuclear power plantKyodo/Reuters
Japan tsunami anniversary
People shout slogans and display banners during a rally criticising the Tokyo Electric Power Company, outside the prime minister's official residence in TokyoToru Yamanaka/AFP
Japan tsunami anniversary
Children wearing padded hoods to protect them from falling debris sit on a playground during an earthquake simulation exercise at a school in TokyoIssei Kato/Reuters
Japan tsunami anniversary
Children take shelter under desks during an earthquake simulation exercise at a school in TokyoIssei Kato/Reuters