Mount Asama

Mount Asama (浅間山, Asama-yama) is an active complex volcano in central Honshū, the main island of Japan. The volcano is the most active on Honshū. The Japan Meteorological Agency classifies Mount Asama as rank A. It stands 2,568 metres (8,425 ft) above sea level on the border of Gunma and Nagano prefectures. It is included in 100 Famous Japanese Mountains. A cruiser class of the Imperial Japanese Navy was named after it, including lead ship Asama.

Geology

Mount Asama sits at the conjunction of the Izu-Bonin-Mariana Arc and the Northeastern Japan Arc. The mountain is built up from non-alkali mafic and pyroclastic volcanic rocks dating from the Late Pleistocene to the Holocene. The main rock type is andesite and dacite.

Scientists from University of Tokyo and Nagoya University completed their first successful imaging experiment of the interior of the volcano in April 2007. By detecting sub-atomic particles called muons as they passed through the volcano after arriving from space, the scientists were able gradually to build up a picture of the interior, creating images of cavities through which lava was passing deep inside the volcano.