The 9.1 magnitude quake was the largest to ever hit the country, causing a 10 metre tsunami that damaged several nuclear reactors.
More than 22-thousand were confirmed dead or missing, and the cost of damage was assessed at about 25-trillion-yen -- 321-billion-New Zealand-dollars.
The Japanese Government estimated the tsunami swept about five-million-tonnes of debris offshore.
Seventy per cent sank -- leaving 1.5-million tonnes floating in the Pacific Ocean.