The Klyuchevskoi Eruptions of 2015-2016.

This paper deals with the summit eruptions of 2015-2016, as well as with the 2016 subterminal eruption of Klyuchevskoi. We estimate the dimensions of the depression that was produced by a landfall in the southeastern trough of the volcano. We estimated the volume and area of landfall deposits. The observed volumes of landfalls during the terminal eruptions of 1944‒1945, 1985, and 2016 can vary within 0.006‒0.140 km³. The theoretical volumes can reach 4‒8 km³. We discuss the leading factors that cause landfalls on Klyuchevskoi. These include irreversible creep at depth, the influence of cracks and fissuring in the volcanic cone, as well as the constant intrusive activity of the volcano. Geodetic measurements revealed that the rates of sliding for several individual patches on the slopes varied between 6.7 cm/yr and 19.4 cm/yr. Video and photographic observations were used to estimate the thermal power of stable steam-gas and ash jets, volume of pyroclastics, and the volume of the erupted lava. The thermal power of the steam-gas jets for 2015 was approximately 122 × 10⁶ kW, that of the gas-ash jets was 5.9 × 10⁶ kW. The volume of discharged pyroclastic material was V = 0.00007 km³ for 2015 and V = 0.0003 km³ for 2016. [ABSTRACT FROM AUTHOR]