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Tokyo Bay

Durham Energy Institute researchers are part of an international collaboration that has developed a novel technique to observe the activity of the ocean close to underwater tunnels in tsunami prone regions.

Understanding the dynamics of the ocean floor

The team used a technique called muography imaging to see underwater activity that is hidden from view.  Sensitive detectors, placed along the length of the Tokyo Bay underwater tunnel, were able to measure naturally occurring cosmic-ray muon radiation that had passed through the sea above. These detectors formed a structure known as an undersea muographic array.

Muography has already been used to successfully image hidden structures, such as the inside of volcanos, nuclear reactors, the Egyptian pyramids, as well as finding evidence of ancient earthquakes. 

This research, published in Nature Scientific Reports demonstrated that it can now be successfully applied even under the ocean. 

When fully developed and mature this undersea muographic array could be widely and easily deployed worldwide, in vulnerable regions.  It is cheaper to build and run than more other established physical mechanisms to measure changes in sea level, such as tide gauges and buoys.  Critically, it provides highly accurate, real-time information and so is a reliable early warning system for tsunami conditions.

Monitoring oceanic hazards

In a preliminary trail, a sensitive undersea muographic array, was deployed in the Tokyo Bay tunnel. The data from the detectors enabled changes in the volume of water above the tunnel to be calculated. For the first time, this accurately detected the mild overhead tsunami associated with the passage of Japan‘s 16th typhoon of 2021. The array has been operating continuously since then.

Early results from this research are promising and the team is planning a deploy similar undersea muographic arrays in other underwater tunnels globally, using both the English Channel Tunnel and the proposed tunnel in the Gulf of Finland.

Jon Gluyas, Director of the Durham Energy Institute said “We are delighted to be part of this truly international effort to use naturally occurring cosmic ray muons to monitor large-scale hazard phenomena here on Earth. The opportunity to monitor both natural and human-made hazards continuously and cost effectively using signals that owe their origin to ancient astronomical events in deep space is both exciting and humbling.”

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