With a detector, it is possible to obtain a two-dimensional image of the bowels of a volcano, “similar to a medical X-ray,” said David Mahon, a muography researcher at the University of Glasgow who was not involved in the study. “By using multiple detectors positioned around the object, it is possible to create a raw 3D image.”
After using muography for see inside a harmless Japanese mountain in 1995, the technique was finally employed in active volcanoes. One of the first successful campaigns was Mount Asama in Japan, where the researchers found a buried lava mound sitting atop a magmatic passage similar to Swiss cheese. It has since been used to see, among others, in Italy Etna Other Stromboli volcanoes, the hyperactive of Japan Sakurajima volcano and the The Soufriere de Guadalupe volcano in the Caribbean.
Muons have found weak spots that suggest the site of future flank collapses, landslides and lava escape routes. They also found cool pockets of magma which can be triggered to erupt and which have been overlooked by other tools.
Volcanic muography is not flawless. The detectors can only see the parts of the volcano where muons are penetrating. “You can only look from below to the sky,” said Marina Rosas-Carbajal, a volcano geophysicist at the Paris Institute of Earth Physics who was not involved in the study. Muons are unable to penetrate into the deepest parts of the volcano, leaving those areas largely off limits to muographers.
Placing detectors around dozens of volcanoes and subjecting volcanic rocks to muons in laboratories will improve the accuracy of the technique as it competes for traditional use. But even if it becomes commonplace, it won’t solve all of our volcanic problems.
“Volcanoes are super complex,” said Dr. Pink Carbajal. Their labyrinthine insides and complex chemicals mean that their magma will occasionally escape even the most crafty of detectors. Unpredictable eruptions will remain a fact no matter how well scientists wield muon magic.
And muography is unlikely to make the other various tools used for obsolete study volcanoes, such as seismic waves and satellite observation. “It may not replace existing techniques,” said Vitaly Kudryavtsev, a particle physicist at the University of Sheffield who was not involved in the study. “But it could integrate them.”