13 years after the Fukushima tragedy, a scientific vessel attempts to unravel the mysteries of earthquakes

A team of scientists aboard the “Chikyu”, one of the world’s largest oceanographic research vessels, is drilling the seabed to better understand what happened on March 11, 2011.

The ship’s mission is to sink a pipe vertically into 7,000 metres of water to reach the seabed, then drill to a depth of 950 metres to take land samples at the confluence of two tectonic plates. Chikyu.

Off the coast of Japan, the ship is exploring the area off the coast of Miyagi and Fukushima prefectures, where a massive 9.0 magnitude earthquake and tsunami occurred on March 11, 2011, killing more than 18,500 people.

After a first mission in 2012, researchers are back on site, in the Pacific, to pierce the bowels of the Earth and see what has been happening there since this earthquake. But to do that, they have to go far, very far: “To be able to assemble a pipe vertically with a total length of 8,000 metres, a boat of this size is needed, otherwise it is impossible.“, assures Nobu Eguchi, director in charge of drilling operations for Japan Maritime-Land Exploration Institute (Jamstec).

The Chikyu is a giant of the seas: at 210 metres long and 40 metres wide, topped with a 130-metre-high derrick, it is quite simply the largest oceanographic research vessel in the world.

“We want to know whether, after a huge earthquake, the forces continue to build up or not. Many researchers are looking forward to this unique opportunity to collect extremely valuable data here to understand why earthquakes of this magnitude occur in subduction zones.“, says mission leader Shuichi Kodaira.

200 people were on board this ship, which was kept motionless in the middle of the sea in the area of ​​the March 2011 earthquake.About thirty researchers from various countries are on board”Nobu Eguchi says. Scientists joined by dozens of engineers and technicians, all English-speaking, specializing in the extremely precise handling of remote-controlled drilling machines.

Also on board, a “large laboratory“, in order to allow the analysis of samples and measurements immediately.”There are several reasons why research should be conducted immediately.says Nobu Eguchi. Under the sea, there is a pressure that disappears on the surface and the more time passes, the more the initial conditions of the sample disappear. There are also microorganisms that live in these depths. And to study them, specialized researchers must recover them immediately. Similarly, the water contained in the rocks collected must also be analyzed without delay just after being extracted before it degrades. That is why we do everything on board“.

Located at the confluence of four tectonic plates, Japan experiences about 20% of the most violent earthquakes recorded on Earth each year. But while they can be explained, these land movements remain unpredictable.