Estimation of Klyuchevskoy Volcano Activity in 2023 based on the SESL’09 technique

\nIn October 2023, Klyuchevskoy volcano (Kamchatka, Russia) erupted, when the height of the ash column reached ~15 km. The eruption was preceded by seismic activity. The dynamics of seismicity in the four most seismically active volumes of the subsoil beneath Klyuchevskoy volcano in the depth range of 4 km above sea level and up to 34 km was analyzed using the “Statistical Estimate of Seismicity Level” methodology – SESL’09. The most pronounced increase in seismicity with an exit to high and extremely high levels was manifested at a depth of 5–8 km 1–3 months before the appearance of lava in the crater of the volcano. The precursor effect detected 1–3 months before the eruption was caused by the redistribution of stresses in the medium containing the feeding magmatic system, the pressure in which varies depending on the conditions of accumulation or supply of magma. After the culmination phase of the eruption, seismic activity at depths of more than 20 km reached an extremely high level. This may be related to the end of the eruption.\n