Год издания: 2020

Explosive volcanoes are associated with a massive ejection of a huge amount of gases and ash that pose a threat for air traffic and population in surrounding areas. However, subterranean precursors of such eruptions are commonly challenging to identify. On December 20, 2017, a strong explosion occurred at Bezymianny in Kamchatka, one of the most active volcanoes of the World, that ejected an ash plume to the altitude of ~15 km. We used the data recorded by temporary and permanent seismic stations to build 3D distributions of seismic wave velocities in the upper crust corresponding to a few days prior to the eruption. The derived model highlights both a shallow magma chamber and a large high-pressure gas reservoir, which is presumed to be the main driver of this explosion. We further test this hypothesis with petrological analysis that is supporting the interaction of the magma and gas sources. The process of fracturing of shallow layers beneath the volcano edifice in the last days prior to the eruption was investigated based on the seismicity evolution, satellite radar imagery and degassing measurements captured by time-lapse cameras.