[Figure 3] Muographic image of Mt. Asama
Colors show the mean density of muons.
Red signifies a higher mean density of muons,
with solid red indicating magma that has
cooled after extrusion.
(C) 2014 Hiroyuki Tanaka
What goes on at the Earth’s interior? New muographic imaging using elementary particles enables a new approach to this question that does not rely on conventional methods of indirect observation.
Hiroyuki Tanaka, Professor at the Center for High Energy gEophysics Research (CHEER), developed muongraphy technology for imaging the interior of the Earth from the surface using highly permeable cosmic rays known as muons. In 2007, he announced his “Muographic Images” showing the interior of Mt. Asama. In 2008, the observation system that deployed the technology was able to verify the magma convection hypothesis of Mt. Iwo on Satsuma-Iwo Island. After shooting intermittently through 2013, Tanaka was able to detect vertical activity of magma at Mt. Iwo.
[Figure 4] The principle underlying the visualization
of the volcanic interior.
The direction and number of muons passing horizontally
through the volcano are measured.
(C) 2014 Hiroyuki Tanaka
Studies using neutrinos, which have much higher penetrating power than muons, are also moving forward. Using “IceCube,” the world’s largest neutrino detector, located in the South Pole, an elaborate project is under way to see through the Earth. The Center joins an international research team with members such as the University of Wisconsin in the ongoing research for the imaging of the Earth’s interior.
[Figure 5] The IceCube neutrino observatory
(C) 2014 The University of Tokyo.
In cooperation with the UTokyo Department of Physics, the Center has long been attempting to integrate particle physics, a field that has led Japan’s science scene to new heights, into geophysics, in order to explore new areas of science. The Center will continue to join domestic and international research efforts to explore phenomena occurring at the interior of volcanoes and the Earth, introducing new perspectives to earth science.
Japan offers many opportunities for research in seismology and volcanology. As more and more observation data is collected, new observation technologies are developed and an increasing number of domestic and international research teams and other connections are forged, the focus of study also expands beyond the boundaries of research of volcanic activity in one country to a study of the entire planet.
What secrets of the Earth will be uncovered next?