Drilling into the crust may provide insight into earthquakes and tsunamis (Image: Jamstec/CDEX)

It sounds like the beginning of a Godzilla movie. Off the coast of Japan, scientists are using a powerful drilling method for the first time in an underwater earthquake zone.

As long as no sleeping monster is rudely awakened by their methods (and no geological nightmares), the team hopes to learn about the frictional properties of the rock in the area in order to better understand how earthquakes and tsunamis form.

The CHIKYU research vessel, operated by the Japan Agency for Marine-Earth Science and Technology, has drilled to a depth of nearly 1.6 kilometres beneath the seafloor while floating on 2 kilometres of ocean. To achieve greater depths than with normal methods, the team uses a technique known as riser-drilling. This relies on recirculating viscous “drilling mud” to maintain pressure balance in the borehole.


According to Bill Ellsworth, of the United States Geological Survey, petroleum drilling on land and from stable ocean oil-platforms regularly reaches depths of between 5 and 8 kilometres. The deepest land-based hole, drilled for scientific research on the Kola Peninsula in Russia, reaches more than 12 kilometres, but drilling from a ship is a different matter.

‘One chance’

Nancy Light of the Integrated Ocean Drilling Program, the organisation that coordinates research drilling projects like CHIKYU, says that this new vessel was designed to drill to depths of 12 kilometres beneath the seafloor, while floating on kilometres-deep, sometimes tumultuous seas. The team say there is no chance of triggering a quake, but despite that the mission is technically difficult.

Ellsworth says that the scientists have one shot to properly install the sensors in the borehole, so they will have to get it right the first time. “It’s risky science, no question about that,” he adds.

While seafloor drilling at Kola-rivalling depths remains to be achieved, the team’s current drilling has already yielded insight into the structure and formation of an area around the Nankai Trough (see map of the region), off the south-east coast of Japan.

The trough is the result of a subduction zone that is created as one piece of oceanic crust – the Philippine plate – is forced beneath another – the Eurasian plate. The huge geological forces at work here are capable of generating magnitude 8 earthquakes and large tsunamis that periodically threaten Asia.

In the coming years, the team plans to put pressure and temperature sensors in the borehole in an effort to find signals that may one day help predict quakes in the region.