Vol 12, No 2 (2018)

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.

This paper presents the results from estimating the predictability of the seismicity of Shiveluch Volcano based on the earthquake catalog for the Northern Group of Kamchatka Volcanoes for 1971–1996 and 1999–2013. The mathematical model that we employed is a nonlinear second-order differential equation, while the algorithms of optimization and predictability are ours. The calculations show that seismicity can be successfully predicted for time intervals of a few weeks to a few months during phases of higher activity and for times of between a few months and a few years during phases of lower seismicity. The prediction distances are in excess of the error by factors of 20 to 50 on average. The nonlinearities in both times of higher and lower rates are close to the law of an equilateral hyperbola. We concluded that the predictability of seismicity can possibly be used in an integrated complex to predict extrusive and effusive activity and accompanying explosive activity. The prediction of major bursts of explosive activity related to failure in the existing volcanic edifice requires additional monitoring of the dome structure and the stability of the rocks that make up the dome.

This study uses macroseismic data and wave equations to solve the problem of ultra long propagation of felt ground motion (over 9000 km from the epicenter) due to the Sea-of-Okhotsk earthquake. We show that the principal mechanism of this phenomenon could be excitation of a previously unknown standing radial wave as a mode of the Earth’s free oscillations, ₀S₀, due to the superposition of an incident and a reflected spherical P wave in the epicentral area of the Sea-of-Okhotsk earthquake. The standing wave generates slowly attenuating P waves that travel over the earth’s surface that act as carrying waves; when superposed on these, direct body waves acquire the ability to travel over great distances. We show previously unknown parameters of the radial mode ₀S₀ for the initial phase of earth deformation due to the large deep-focus earthquake. We used data on the Sea-of-Okhotsk and Bolivian earthquakes to show that large deep-focus earthquakes can excite free oscillations of the Earth that are not only recorded by instrumental means, but are also felt by people, with the amplification of the macroseismic effect being directly related to the phenomenon of resonance for multistory buildings.

This paper reports the development of a new-generation short-period borehole electrodynamic seismometer designed for research, with special emphasis on seismology and volcanology (Sobisevich et al., 2008) and for important applications (Bashilov, 2001), e.g., developing special monitoring and security systems, as well as the search for and monitoring of hydrocarbon exploration.