Tokyo ? A research team has succeeded in taking images of the inside of a volcano using cosmic rays, the first time visual images of the structure inside a volcano have been obtained using this method.

The X-raylike images of Japan’s Mount Asama were made by researchers from Tokyo University and Nagoya University. It is the first time scientists have been able to produce an image of the interior structure of a volcano. Previously such information had only been estimated through analysis of seismic waves.

The images were made using muons – microscopic particles that react with the earth’s atmosphere when they fall from space.

The team produced the image by observing muons that fall from space at a rate of one per second onto a palm-sized area. The thicker the object they fall on, the more they are absorbed.

The results of the analysis completed in April showed cavities that magma passes through, hollows in the crater and hardened high-density lava layers that formed at the bottom of the crater after the volcano’s 2004 eruption.