Lake Towada

The lake-filled, 11-km-wide, Towada caldera in northern Honshu formed during as many as six major explosive eruptions over a 40,000-year period ending about 13,000 years ago. Pre-caldera eruptive activity dates back about 2 million years and produced basaltic-to-dacitic lava cones. Following late-Pleistocene andesitic-to-rhyolitic caldera-forming eruptions, the basaltic Ninokura stratovolcano grew in the SSE section of the caldera. Successive dacitic-to-rhyolitic explosive eruptions from the Goshikiiwa cone led to the formation of the roughly 2-km-wide Nakanoumi caldera, whose SW and NE rims form peninsulas extending into Lake Towada. The andesitic-to-dacitic Ogurayama lava dome was built over the NE rim of Nakanoumi. The latest eruption took place in 915 CE, when eruptions from Ogurayama produced widespread ashfall and pyroclastic flows.