Mount Asama, or Asamayama in Japanese, is the most active volcano on the island Honshu and is located 90 miles northwest of Tokyo. The volcano is 8,344 feet above sea level, and the mountain rises above the resort town of Karuizawa. Asama is a stratovolcano with three overlapping parts situated a few miles apart.
The oldest part of the volcano is the western crater that is 1.25 miles wide due to erosion over hundreds of thousands of years. This crater fills with water and drains to the southwest. This part of Mount Asama is more than a mile away from the active stratovolcano.
The newest portions of Mount Asama are comprised of two craters. The outer crater is nearly 4,000 feet wide. The cone of the main volcano rises 560 feet above the outer crater of the newer stratovolcano. All eruptions during recorded history came out of this cone.
As of July 2014, the most recent eruption of Mount Asama occurred in February 2009. Nearly 45,000 residents close to the volcano were put on alert when ash and dust spewed from the snow-capped cone of Mount Asama. The earliest eruption of the stratovolcano, according to radiocarbon dating by scientists, was nearly 9,000 years ago. The first historical observations of volcanic activity from Mount Asama were in 1108 A.D.