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, 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 8.0 on the Volcanic Explosivity Index, making the Ōkueyama eruption one of the largest eruptions in recorded history. The mountain is now considered to be extinct.