(ORDO NEWS) — We are all aware of the devastating effects of tsunamis, and the possibility of a tragedy continues to drive research to improve detection methods. A new study reports a novel approach to tsunami detection: muon monitoring.
These high-energy elementary particles are produced by the arrival of cosmic rays from outer space, are found throughout the atmosphere, and can harmlessly pass through almost anything, including you: 100,000 of them will pass through your body as you read this sentence.
It is very important that they can be very slightly displaced in their path under the influence of large natural forces, including tsunamis.
Muon motion detection requires an incredibly sensitive instrument, which led us to the Tokyo Bay Seabed Hyperkilometer Underwater Depth Detector, or TS-HKMSDD for short. It is installed inside the Tokyo Bay Aqua-Line expressway tunnel.
TS-HKMSSD had the honor of detecting tsunami waves from muon pulsations for the first time. Important in terms of early warnings, the detection occurred in real time and showed high accuracy.
“The Hyperkilometer Underwater Deep Detector on the Tokyo Bay Seabed is the world’s first underwater muon observatory, and it detected the changing muon activity during the tsunami,” says geophysicist Hiroyuki Tanaka from the University of Tokyo in Japan.
“These fluctuations are consistent with ocean disturbances that have been measured by other methods. Combining these readings means that we can use muographic data to accurately model sea level changes, bypassing other methods, which have their drawbacks.”
These other methods include tide gauges, buoys in the water, satellite imagery taken from above, and various sensors in the sea itself. Muon detection, however, promises to be faster, cheaper, and easier to maintain than these methods.
A new study describes how the TS-HKMSDD system detected a weak tsunami that passed through Tokyo Bay in September 2021, caused by a typhoon approaching Japan from the south. When the ocean heaved, the number of muons changed slightly, dissipating depending on the volume of water.
Now that TS-HKMSSD has shown it can detect these muon shifts, the researchers are proposing to install similar instruments in other tunnels in tsunami-prone areas and use them alongside equipment such as tide gauges as part of early warning systems.
“Thanks to the success we’ve had in early testing, similar systems are already being tested in the UK and Finland,” says Tanaka.
“Obviously, such an undertaking is fraught with difficulties, and the installation of delicate instruments in a busy tunnel may be difficult. But we are grateful for the cooperation of the agencies responsible for the Tokyo Bay Tunnel.”
The muon detectors included with TS-HKMSSD are actually quite small, around 2 meters (6.5 feet) long. Currently, 20 of them are deployed along the Tokyo Bay Road Tunnel, working together to create a common system.
In addition to detecting upcoming tsunamis, a similar system could be used to search for natural gas reserves and identify ancient earthquake patterns.
For now, the researchers are pleased that the TS-HKMSSD is working as an accurate tsunami detector that, with further work, could be used to warn experts of natural disasters.
“To my knowledge, the tunnel is the world’s first operational national road designated as a laboratory,” says Tanaka.
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