The earthquake and tsunami left more than 18,000 people dead or missing
Services have been held in Japan to mark the devastating earthquake and tsunami that struck two years ago.
Ceremonies took place in the three worst-hit prefectures and a minute's silence was observed at 14:46 (05:46 GMT), when the quake hit.
More than 18,000 people were left dead or missing in the disaster, which also caused the Fukushima nuclear crisis.
Since then, most of Japan's nuclear reactors have remained off, amid impassioned debate over nuclear energy.
On Sunday, thousands of people marched in Tokyo urging an end to the use of nuclear power. Japan's 50 nuclear reactors were shut down for checks after the earthquake and only two have since been turned on again.
But Prime Minister Shinzo Abe, who was elected in December, has indicated he wants to restart the reactors after safety checks to meet pressing power needs.
About 160,000 people had to be evacuated from the area around the nuclear plant, where meltdowns occurred at three reactors after tsunami waters knocked out cooling systems. It remains unclear if they will ever be able to return.
Tens of thousands of people also remain displaced further north, after entire communities were washed away or felled. The government has channelled billions of dollars into reconstruction, but has been criticised for slow progress.
In a video message posted on YouTube on Monday, Mr Abe pledged to accelerate reconstruction work.
"Japan will never experience a true spring if spring does not come to north-eastern Japan. I promise never to forget the weight of each day and promise to speed up the reconstruction of the region," he said.
Both he and the Imperial couple, Emperor Akihito and Empress Michiko, attended a memorial service in Tokyo, where they observed the silence.
According to an official tally, 15,881 people died in the disaster and 2,668 others remain unaccounted for.