Deep dive into earthquake detection

Robot developed for a global competition could now help to predict the next big earthquake in Japan

By Soh Chin Ong on Jan 13, 2020

On March 11, 2011, Takeshi Ohki was supposed to have been testing a land robot in Sendai city, along Japan’s north-east coast.

Instead, he was fast asleep when the Great East Japan Earthquake – the country’s most powerful to date – struck the area, jolting him out of bed in the afternoon. The magnitude nine earthquake shifted the earth’s axis by between 10cm and 25cm, moving the country’s main island, Honshu, more than two metres closer to the USA.

Ohki, who was then an engineering graduate student at Tohoku University, had decided to abandon the experiment in the early hours of the morning because of a defective component in the robot.


Takeshi Ohki’s work could help detect earthquakes in the region.
Takeshi Ohki’s work could help detect earthquakes in the region. Image: Team Kuroshio

“If it had worked, I would have been on the beach. And I wouldn’t be here today,’’ he says.

The earthquake caused a 14m-high tsunami which destroyed the Fukushima Daiichi nuclear plant. At Sendai, the waves swept inland, giving people only minutes to escape. Some 20,000 people died in the tragedy.

Ohki, shaken by the incident, was determined to make a difference. He felt a better understanding of the ocean depths could lead to better detection of future earthquakes.

In 2015, he decided to take part in Shell’s Ocean Discovery XPRIZE, a three-year contest, in which 32 teams from around the world competed to develop unmanned, high-resolution undersea exploration systems.

Globally, little headway has been made in mapping the ocean floor because of high costs and difficult logistics.

“About 70% of the world is covered by ocean. Yet little is known about it,” says Martin Stauble, Shell’s VP of Exploration North America and Brazil. “We supported the contest to promote the development of undersea technology that could ultimately benefit all of humanity.’’

Ohki gathered around 30 people from eight companies and organisations across Japan to form a team called Kuroshio, named after the North Pacific Ocean current which flows past the country. 

Team Kuroshio came in second, but one of the autonomous underwater vessels (AUVs) it used in the contest, called the AUV-Next, will be deployed by the Japan Agency for Marine-earth Science and Technology (JAMSTEC) for a survey mission in the Nankai Trough off Japan’s east coast. This is where region’s next big earthquake is expected to originate in the next 30 years.

Morifumi Takaesu was part of Team Kuroshio
Morifumi Takaesu was part of Team Kuroshio. Image: Team Kuroshio

The AUV-Next was one of a system of AUVs used to map the ocean floor. In the contest, data was then transmitted by satellite, via a surface vessel, to a base station on land.

The competing teams had to map 500 sq km of ocean floor – about the size of Chicago – at a depth of 4,000m. Under contest guidelines, the 3D images had to be of a high resolution of at least 5m horizontally and 0.5m vertically.

“This was significant because existing mapping systems tend to be of a higher resolution, focusing on narrow areas,” says Kuroshio member Morifumi Takaesu, who works for Nippon Marine Enterprises, a company that operates marine vessels and conducts deep-sea research.

“The contest made us focus on vast areas, in a shorter space of time, which might be also useful in detecting tectonic patterns and movements on the seabed. More research is needed, of course. But we can certainly build on this data.’’

Ohki, who now works for JAMSTEC, believes the contest has generated more interest in understanding the ocean depths.

“It has certainly created momentum, bringing together a community of underwater researchers and engineers from around the world, who can now share their work and collaborate on future projects.’’

 “The Shell Ocean Discovery XPRIZE is a testament to the power of ideas and collaboration to solve big problems,” says Stauble. “At least 25 patents have come from the contest, all belonging to the contestants. These new technologies will hopefully lead to more breakthroughs, not only in oil and gas exploration, but also in improving lives."


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