Mount Ōkueyama (大崩山), also known as Mount Ōkue, is a volcanic mountain on the Japanese island of Kyushu. Part of an ancient volcanic formation known as the Okueyama Volcano-plutonic Complex,Takahashi, Masaki. Subsurface Structure of Miocene Large-scale Caldera Cluster: Illustrated Descriptions of Geology of the Okueyama Volcano-plutonic Complex, Southwest Japan. Received November 16, 2013
URL: https://www.chs.nihon-u.ac.jp/institute/nature/kiyou/2014/pdf/2_11.pdf Mount Ōkueyama (and possibly several nearby volcanoes) experienced a massive eruption ~13.7 million years before present (13.7 Ma); it has been postulated that this eruption measured 8 on the Volcanic Explosivity Index, making the Ōkueyama eruption larger than any eruption in recorded history.Daisuke, Miura; Yutaka, Wada (2007). "Middle Miocene ash-flow calderas at the compressive margin of southwest Japan arc: Review and synthesis". The Journal of the Geological Society of Japan. 113 (7): 283–295. doi:10.5575/geosoc.113.283. Retrieved 8 August 2019. The volcano is now considered to be extinct.
In 1990, the area around the mountain was designated a Forest Ecosystem Reserve, and In 2017 Mount Ōkueyama was declared part of a UNESCO biosphere reserve, the Sobo, Katamuki and Okue Biosphere Reserve.
The area is managed by the Forestry Agency of Japan.
See also List of mountains in Japan List of volcanoes in Japan
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