BackgroundAtsonupuri volcano has a somma volcano (the remnant of an older edifice) whose rim is exposed at 900 m elevation on the SE side. The precessor of Atsonupuri was active in the late Pleistocene or early Holocene and once formed an island up to about 1.5 km high, which was later connected to Iturup Island by sediments.
An important normal fault cuts through the NW side of the somma of Atsonupuri (also known as Etorofu-Atosanupuri).
The 2-km-wide caldera was largely filled and overtopped by a central cone that forms the present-day summit.
See also: Sentinel hub | Landsat 8 | NASA FIRMS