Mount Aso

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Mount Aso
Central cone group of Aso caldera
Highest point
Elevation1,592 m (5,223 ft)
Coordinates32°53′04″N 131°06′14″E / 32.88444°N 131.10389°E / 32.88444; 131.10389Coordinates: 32°53′04″N 131°06′14″E / 32.88444°N 131.10389°E / 32.88444; 131.10389
Native name阿蘇山  (Japanese)
Mount Aso is located in Japan
Mount Aso
Mount Aso
Kyushu, Japan
Mountain typeCaldera complex
Last eruptionOctober 2016 - Present

Mount Aso (阿蘇山, Aso-san) is the largest active volcano in Japan, and is among the largest in the world. It stands in Aso Kujū National Park in Kumamoto Prefecture, on the island of Kyushu. Its peak is 1,592 meters (5,223 ft) above sea level. Mount Aso has a fairly large caldera (25 kilometers (16 miles) north-south and 18 km (11 mi) east-west) with a circumference of around 120 km (75 mi), although sources vary on the exact distance.


Central Cone
Mount Naka (Naka volcano)
The steaming crater of Mount Naka

The central cone group of Aso consists of five peaks: Mt. Neko, Mt. Taka, Mt. Naka (also called Nakadake or Naka-Dake), Mt. Eboshi, and Mt. Kishima. The highest point is the summit of Mt. Taka, at 1592 m above sea level. The crater of Mt. Naka, the west side of which is accessible by road, contains an active volcano which continuously emits smoke and has occasional eruptions. Only the northernmost crater (the first crater) has been active for the last 70 years—1974, 1979, 1984–1985, 1989–1991,[1] 2009, 2011, 2015[2] and 2016.[3][4]

The present Aso Caldera formed as a result of four huge caldera eruptions occurring over a range of 90,000–300,000 years ago.[citation needed] The caldera, one of the largest in the world, contains the city of Aso as well as Takamori and Minamiaso enclosing the caldera extends about 18 km east to west and about 25 km north to south. Viewpoints from the somma overlooking the caldera are perched upon lava formed before the volcanic activity which created the present caldera. Ejecta from the huge caldera eruption 90,800 years ago covers more than 600 km3 and roughly equals the volume of Mount Fuji; it is presumed[by whom?] that the pyroclastic flow plateau covered half of Kyushu.


The eruption which formed the present somma occurred approximately 300,000 years ago. Four large-scale eruptions (Aso 1 – 4) occurred during a period extending from 300,000 to 90,000 years ago. As large amounts of pyroclastic flow and volcanic ash were emitted from the volcanic chamber, a huge depression (caldera) was formed as the chamber collapsed. The fourth eruption (Aso 4) was the largest, with volcanic ash covering the entire Kyushu region and even extending to Yamaguchi Prefecture.

Mt. Taka, Mt. Naka, Mt. Eboshi, and Mt. Kishima are cones formed following the fourth above-mentioned huge caldera eruption. Mt. Naka remains active today. It is presumed[by whom?] that Mt. Neko is older than the fourth huge caldera eruption. Aso's pyroclastic flow deposits (welded tuff) were utilized for bridge construction in the region, There are approximately 320 arched stone bridges in Kumamoto Prefecture, including the Tsujun-kyo and Reitai-kyo bridges on the Midorikawa River, which are important national cultural properties.[1]


With an elevation of 1,143 metres (3,750 ft).[5], Mount Aso has a climate that falls as humid continental (Köppen climate classification "Dfb"), with warm summers and cold winters. Precipitation is high throughout the year, which brings the area to have borderline subtropical characteristics as well. They are particularly heavy in June and July, where over 500 millimetres (20 in) of rain fell in each month.


Prior to April 2016 (when the cable car was closed), the Mount Aso Ropeway provided access to the mountain. A shuttle bus now runs to the crater's edge.

At the foot of the mountain there are also various campsites, and horse riding at Kusasenrigahama.[6]

Because Mount Aso is a volcano, there are many onsen hot springs in the area. There are two hot springs within the crater that are associated with Aso Kujū National Park.[citation needed]


  • "Asosan". Global Volcanism Program. Smithsonian Institution.

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