Towada

Geography & Climate

Towada is located in Japan, within the Northeast Japan Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 40.51° N, 140.88° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 1,011 meters above sea level, Towada is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a caldera, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Towada sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Japan near Towada, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Towada has 8 recorded eruptions in the geological database, spanning from 9490 BCE to 915 CE. The most powerful recorded event was a paroxysmal eruption with devastating regional consequences in 915 CE, reaching VEI 5 on the Volcanic Explosivity Index. Notable eruptions include 915 CE (VEI 5), 750 BCE (VEI 4), 4150 BCE (VEI 5). This eruption frequency indicates a moderately active volcanic system with periodic reawakenings.

Significance

With a maximum recorded VEI of 5, Towada has demonstrated the capacity for paroxysmal eruptions comparable to the 1980 eruption of Mount St. Helens. Eruptions of this scale can devastate areas within 20-30 kilometers and produce ash fall that disrupts aviation and agriculture across hundreds of kilometers. With 8 recorded eruptions on file, Towada has enough documented activity to help scientists identify patterns in its eruptive behavior.

GVP Reference Summary

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.

— Smithsonian Institution, Global Volcanism Program