An innovative imaging system that uses muons – a type of cosmic ray – to reveal the interior of a volcano has been developed by scientists at the University of Tokyo’s Earthquake Research Institute.
Muons are high-energy elemental particles that result from collisions between cosmic rays and molecules in the Earth’s upper atmosphere. Hold out your hand and a muon would pass through it about once every second. Chief Scientist Dr. Kanetada Nagamine of the Muon Science Laboratory at RIKEN (Japan’s national science research institute) is big on muons, to say the least.
Opines Nagamine, “If the 20th century was the electron age, the 21st century could be the muon age.” One might think that’s going a bit far, but the professor knows a thing or two about muons – among other things, he uses them to look inside volcanoes.
“The muons’ ability to penetrate matter depends on their energy,” explains Dr. Nagamine. “Muons with energies of 100 giga electron volts can pass through 100 meters of rock, and muons with energies of 1 tera electron volts can penetrate 1000 meters into the Earth.”
Based on the wide range of energies, Nagamine’s team designed an imaging system that records hits from muons which pass through a volcano to reach the detector. A radiograph-style image illustrating the density of the volcano is then gradually created using colors to denote muons of different energies.
Although it takes up to 2 months to create a suitably detailed image, that’s more than enough time for scientists to see magma moving up the throat of the volcano and, if necessary, alert governmental authorities that an eruption may be imminent. On the lighter side, any concerned homeowners looking to buy volcano insurance may want to chat up Dr. Nagamine first.