Kuttara

Geography & Climate

Kuttara is located in Japan, within the Northeast Japan Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 42.49° N, 141.16° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 549 meters above sea level, Kuttara is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Kuttara 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 Kuttara, 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 basalt / picro-basalt, 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

Kuttara has 3 recorded eruptions in the geological database, spanning from 8050 BCE to 1820 CE. The most powerful recorded event was a gentle, effusive event in 1820 CE, reaching VEI 1 on the Volcanic Explosivity Index. These eruptions span roughly 9,870 years of volcanic history.

GVP Reference Summary

The Kuttara volcanic group consists of a series of small stratovolcanoes, lava domes, pyroclastic cones, and a caldera near the Pacific coast SE of Toya caldera and SW of Shikotsu caldera. The Kuttara group was constructed during five major eruptive stages, the first of which occurred more than 60,000 years ago. A major dacitic pumice eruption at the end of the 4th stage about 40,000 years ago resulted in the formation of the 3-km-diameter Kuttara caldera. The caldera cut a basaltic-to-andesitic stratovolcano complex, which late in its activity produced two major andesitic lava flows on its north side at Kita-yama. Explosions, probably in early Holocene time, formed two large craters on the west flank of the caldera, and a dacitic lava dome was emplaced about 10,000 years ago. Late-stage phreatic explosion products from Jigoku-dani, a 300-400 m wide crater south of the lava dome, overlie the 1663 tephra from Usu volcano. Jigoku-dani and Noboribetsu Spa are the sites of intense thermal activity, including fumaroles, hot springs, and geysers.

— Smithsonian Institution, Global Volcanism Program