Rausudake

Geography & Climate

Rausudake is located in Japan, within the Kuril Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 44.08° N, 145.12° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 1,660 meters above sea level, Rausudake 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

Rausudake 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 Rausudake, 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

Rausudake has 5 recorded eruptions in the geological database, spanning from 270 BCE to 1800 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 550 CE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 1800 CE (VEI 3), 1350 CE (VEI 3), 550 CE (VEI 4). This eruption frequency indicates a moderately active volcanic system with periodic reawakenings.

Significance

With a maximum recorded VEI of 4, Rausudake has demonstrated the capacity for significant explosive eruptions that can impact regional aviation, agriculture, and communities tens of kilometers from the summit. VEI 4 eruptions produce ash columns reaching 15-25 kilometers into the atmosphere. With 5 recorded eruptions on file, Rausudake has enough documented activity to help scientists identify patterns in its eruptive behavior.

GVP Reference Summary

Rausudake is an andesitic-to-dacitic stratovolcano with summit lava domes on the Shiretoko Peninsula in NE Hokkaido. The 1660-m-high volcano is located along a ridge 5 km SW of Shiretoko-Iozan volcano, the NE-most Holocene volcano in Hokkaido. Young lava flows descend the NW flank and broad areas along the SE flank, and an older lava flow traveled about 9 km W, reaching the coast of the Sea of Okhotsk along a broad front. Eruptions produced pumiceous tephras with associated pyroclastic flows about 2200, 1400, and 800 years ago. Recent work has documented a pyroclastic-flow deposit that overlies the 1739 tephra from Tarumai volcano in SW Hokkaido. Stratigraphic relationships place this eruption, the most recent known from Rausudake, between about 1750 and 1850 CE.

— Smithsonian Institution, Global Volcanism Program