Etorofu-Atosanupuri [Atosanupuri]

Geography & Climate

Etorofu-Atosanupuri [Atosanupuri] is located in Japan - administered by Russia, within the Kuril Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 44.81° N, 147.13° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 1,206 meters above sea level, Etorofu-Atosanupuri [Atosanupuri] 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

Etorofu-Atosanupuri [Atosanupuri] 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 - administered by Russia near Etorofu-Atosanupuri [Atosanupuri], 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

Etorofu-Atosanupuri [Atosanupuri] has 2 recorded eruptions in the geological database, spanning from 1812 CE to 1932 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1932 CE, reaching VEI 2 on the Volcanic Explosivity Index. These eruptions span roughly 120 years of volcanic history. The most recent eruption in 1932 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

The conical Etorofu-Atosanupuri stratovolcano forms a prominent peninsula joined to the SW side of Iturup (Etorofu) Island by a low isthmus only 30 m high. A somma volcano whose caldera rim is exposed only at about 900 m elevation on the SE side was constructed during the late Pleistocene or early Holocene, forming an island up to about 1.5 km high that was later connected to the main island by erosional material. A fault with large displacement offsets the NW side of the somma. The 2-km-wide caldera was subsequently largely overtopped by a central cone that forms the present summit. Strombolian eruptions have dominated the history of this basaltic volcano; few lava flows are exposed. Only two historical eruptions are known, during 1812 and 1932.

— Smithsonian Institution, Global Volcanism Program