The quake caused a massive tsunami - sparking a nuclear disaster at a power plant - that killed 15,850 people, injured 6,011 others and left a further 3,287 people missing.
For safety reasons many people are still staying away from the disaster zone, on the east coast of the Tohoku region of the Japanese island of Honshu, but some are going there to help survivors. Hongkonger Louis Choi Ka-fai is one of them.
"I was sad about what happened in Japan and I wanted to help," says the 31-year-old, who runs his own IT business.
Choi did not hesitate to volunteer to work as a photographer for the Hong Kong charity Post Crisis Counselling Network (PCCN) after spotting a recruitment advertisement on the organisation's website. He joined a team of counsellors that made five, week-log trips last year to Iwate, Hanamaki, Rikuzentakata, Minamisoma and Sendai, which were affected by the tsunami. Each visit was a highly emotional experience.
"In a relief shelter, I met an old lady who was looking at some photographs," he says. "I asked her who the people were in the photos and she said they were her grandchildren. Later, I learnt that her grandchildren had been killed; she'd just gone to the funeral.
"We'd met as she was sorting through photos for their tombstones. It was heartbreaking; it made me cry."
"Another traumatised man refused to speak," Choi says. "He'd lost his guitar; it was so important to him - a lifeline."
The charity looked in Hong Kong for someone that could donate a guitar. "When he received the guitar, he smiled for the first time and was willing to talk," Choi says. "He even taught us some songs. I was very touched to see how we had helped him."
Yet he knows that it will be a long journey to full recovery for these people, after having accompanied the counsellors helping to ease the victims' suffering.
Timothy To Wing-ching, executive director of PCCN, who has led a group of counsellors on eight trips that helped 1,583victims, says: "Like all survivors of natural disasters, they're suffering post-traumatic stress disorder. One common symptom is having vivid images in their mind, as if they're reliving the event.
"Some 'feel' they're still experiencing the earthquake or tsunami and are so frightened they lock themselves in their bathrooms; others 'smell' radiation and have to close all the windows to shut it out."
PCCN has been working with the Japan government to help survivors recover from their trauma, including training 120Japanese people to work as counsellors.
Choi's work in Japan has given him a new perspective of life. He says: "Looking at all the debris everywhere, I wondered what it had been part of before the disaster. It made me realise how trivial our materialistic world is.
"I saw that victims wished only for their dead loved ones to be still alive. I remember the emotion - the tears in the eyes - on each one of the faces of a family that survived, as they looked at a family photo I took for them. I saw the relief in all their faces. It made me just want to spend more time with my parents and my younger sister."
His photos, collected into three themes, "Disaster", "Recovery" and "Alive", are part of the exhibition, Japan Alive! Smile Again, on show at Plaza Hollywood, in Diamond Hill, until March 20.
PCCN is also looking for more volunteers, especially translators, for 12 future visits to Japan. Anyone aged 23 or over and fluent in both Cantonese and Japanese can apply. Training will be provided.
For details, go to www.pccnhk.org.