The History of Mt. Asahidake
Mt. Asahidake rises 2,291 meters and is the highest mountain in Hokkaido. It forms part of the Daisetsuzan Volcanic Group and is an active volcano. The horseshoe-shaped crater at the foot of the mountain is called Jigokudani (literally, “hell valley”). The crater has numerous active vents that emit hot steam and sulfurous gases.
Mt. Asahidake has repeatedly collapsed and subsided over time. What was once the side of the mountain now constitutes the summit. Jigokudani is the result of a collapse thought to have occurred about 2,900 years ago, though it is difficult to precisely date the mountain’s activity due to a lack of historical records.
The Daisetsuzan area formed about 10 million years ago when the Okhotsk Plate and the Pacific Plate collided, causing enormous pressures that melted underground rock. This gave rise to volcanoes, which in turn created the topography seen today.