A New Zealand geologist and other world-leading scientists believe they've identified the key trigger of the devastating Fukushima tsunami of 2011.
It was the fine sediment clay in the area, and it's very similar to what lies on the sea floor off New Zealand's east coast.
The results from drilling deep into the Japan Trench have excited geologists everywhere, including the only Kiwi on board.
"The composition of the rock is surprising - it turns out to be 78 percent smectite, which is a clay mineral which results possibly from the breakdown of volcanic glass, much like New Zealand," says Dr Virginia Toy of the University of Otago.
The magnitude 9 quake that rocked Japan and the wall of water that followed killed more than 15,000 people in March 2011.
What the 27 international scientists on board the Chikyu found when they drilled into the fault zone was volcanic sediment so slippery and so weak it could've caused not only the quake, but displaced enough water for the 10m tsunami that followed.
"When we reached that we realised this was probably where earthquakes had been happening for hundreds, if not thousands of years," says scientist James Mori.
New Zealand's own Hikurangi Trench off the east coast from Kaikoura to Bay of Plenty and up towards Tonga is thought to have similar sediment. So just how vulnerable are we?
"The geology on land in New Zealand is similar to Japan, we are providing lots of volcanic ash into that subduction system, so it has the potential to generate large slippage and large tsunami," says Dr Toy.
When, no one can predict, but if a proposal currently before international officials goes through, this leading team of scientists could be heading our way in 2016, drilling for clues 100km off New Zealand's east coast.