The Creation of Hakone volcano
Mt. Hakone is one of Japan’s representative volcanoes. It was formerly presumed that an extensive volcano had been created through implosion. However, recent research has led to a predominant theory of conglomeration of multiple volcanoes.
① 400,000 to 230,000 years ago
Some 400,000 years ago, the Hakone volcano started to erupt, forming volcanic groups by repeated eruptions of varying sizes on a medium to small scale. The lava that created Mt. Kintoki, Yamabushi Pass, Mt. Myojin, Mt. Myojo, and Mt. Marudake, derived during this period.
② 223,000 to 130,000 years ago
Pyroclastic flows were caused by numerous large-scale eruptions in the central part of this volcanic group so that the existing group was destroyed. The result was the formation of a caldera in the central volcano and the outer ring mountain in the surrounding area.
③ Years between; 130,000 to 80,000
While large scale volcanic eruptions had continued, there were many volcanoes formed within the caldera. Mt. Takanosu, Mt.Asama, Mt. Byobu are examples of these early central crater hills.
④ 80,000 to 40,000 years ago
Some 60,000 years ago, an additional new caldera was created by repetitive explosive eruptions. This powerful volcanic eruption dispersed volcanic ejecta over an extensive area. So-called Tokyo Pumice is still found in many locations, from the foothills of Mt. Fuji to the southern Kanto region.
⑤ 40,000 years ago to present
Eruptions on a smaller scale still continued. A thick, sticky lava erupted and hardened inside the caldera, forming numerous domed-shaped mountains. The late central crater hills of Mt. Kamiyama, Mt. Futagoyama, Mt. Daigatake, Mt. Kozuka were formed in this way.
Some 3,000 years ago, Mt. Kanmuri was formed as a result of eruptive activity. Then, immediately, the subsidence created by the landslide of Mt. Kamiyama blocked the Hayakawa River. This, in turn, resulted in the present configuration of Lake Ashinoko.
