Determination of the volcanic eruption source parameters—total grain-size distribution and vertical ash mass distribution (VMD) within the source—is carried out on a collection of measured-area samples and granulometry data. For this, the geophysical inverse methods and Hybrid Particle and Concentration Transport Model (HYPACT) driven by wind and turbulence fields simulated with the Regional Atmospheric Modeling System (RAMS) are used. A two-step inversion procedure is proposed to obtain approximate but physically meaningful solution when the total number of ashfall samples is small and it is not possible to make a good initial guess of the source parameters. First, a spectrum of particle fall velocities is estimated by selecting a best-fit subset of aerodynamically distinct subpopulations of free and aggregate particles from the trial set used to simulate a polycomponent ashfall. The singular value decomposition (SVD) analysis is then employed to identify spatial components of the ash emissions’ vertical distribution, as resolvable by the observations. Model validation experiments are conducted for the January 12, 2011, short-duration vulcanian explosion at Kizimen and paroxysmal phase of the December 24, 2006, sub-Plinian eruption at Bezymianny. The derived VMDs exhibit high variability in fine ash content (~ 60–100 wt%) as well as strong secondary maxima in the lower troposphere, likely reflecting the contribution of ash particles fallen out of co-pyroclastic flow ash clouds and partially collapsing eruption columns.

The current problems of hydrothermal processes and ore-forming systems are volcanic heat sources and mechanisms of heat
transfer. In Pauzhetsky, Semyachik and Mutnovsky geothermal areas in Kamchatka, active long-lived volcanic centers have been
studied, with which high-temperature hydrothermal systems are associated. In the Banno-Paratunsky geothermal area the Paleogene
and Neogene long-lived volcanic centers were identified, with which low-temperature hydrothermal systems are associated. The
geological history of the long-lived volcanic centers development is characterized by changes in their structure as a result of
hydrothermal-magmatic activity. These changes are manifested in the generation and evolution of magma chambers in the mantle
and in the Earth’s crust. Basalt melts of the mantle chambers transport the deep heat to the Earth’s surface through plane magmatic
channels without significant losses. The heat flow of these volcanic centers is short-lived and is characterized by a significant
capacity of ~8,000 kcal/km2s. The long-lived volcanic centers are characterized by the presence of magma chambers in the Earth's
crust. They shield the part of the mantle heat flow. Their thermal capacity on the Earth's surface is estimated from 1000 kcal/km2s
to 5000 kcal/km2s. It is assumed that a significant amount of thermal energy is retained in the long-lived volcanic centers. It is
spent on formation and activity of the chambers as well as the convective hydrothermal ore-forming systems. The evolution of such
centers is accompanied by the formation of complexes of metamorphic rocks which interaction with high-temperature mantle melts
is accompanied by redox reactions like combustion. As a result of these reactions, thermal energy is produced in such magma
chambers. A long-lived jet magmatic system is formed, and it provides the transfer of mantle heat. Heat transfer in the system is
accompanied by minimization of heat losses, accumulation of heat and its additional generation which is necessary for the heat
transfer in the structures with low thermal conductivity. The formation, evolution and extinction of magma chambers and reservoirs
in such heat-conducting structures are controlled by the thermophysical properties of the rocks, their geological structure and redox processes in them.

Поступила в редакцию 1. 11. 2006 г.
Методом сейсмической томографии построена объемная скоростная модель земной коры под Ключевской группой вулканов. Выделены аномалии скоростных параметров связанных с зонами магматического питания активных вулканов. Получены петрологические данные о составе, температуре и давлении генерации и кристаллизации родоначальных расплавов магнезиальных базальтов Ключевского вулкана. Родоначальный расплав отвечает пикриту (MgO=13-14%,мас) с предельным насыщением SiO2 (49-50%, мас.), высоким содержанием H2O (2,2-2.9%) и несовместимыми элементами (Sr, Rb, Ba, Hf). Он образуется при давлениях 15-20 кбар и температурах 1280-13200С. Его дальнейшая кристаллизация проходит в промежуточных магматических камерах при двух дискретных уровнях давлений (более 6 и 1-2 кбар). Результаты петрологических исследований находятся в хорошем соответствии с сейсмотомографической моделью.

Mutnovsky geothermal area in Kamchatka, Russia where 62 MWe GeoPP installed - is a source of geothermal electricity supply, as well as a hazard volcanic area. We used local seismicity micro-earthquakes (MEQ’s) data from 2009 to 2021 to define seismogenic faults beneath and adjacent to Mutnovsky volcano, which interpreted as magma injections in form of dykes and sills. Magma fracking beneath Mutnovsky volcano pointed on shear mode low angle dykes in northeast sector and opening mode geomechanical conditions at -3000 m, where sills in area of 62 km2 are suggested to be formed. Low angle dykes injections were reproduced by hydromechanical simulation using CFRAC, modeling results matches with MEQ’s statistics observed.
Mutnovsky GeoPP steam collection system shows sensitivity to non-condensable gasses (NCG) content (partial gas pressure) variations (2019—2020), that is used as indicator of magmatic gasses recharge via magma fracking volcano system to production geothermal reservoir. Partial gas pressure measured at GeoPP condenser unit. Magma injections associated with NCG (CO2) release in production reservoirs seems to be synchronize with partial NCG pressure excursions at GeoPP condenser. Some signs of magma fracking events were also revealed using discreet observations (2016–2021) on a blowing wells on a foothills of Mutnovsky volcano. Magma fracking beneath Mutnovsky volcano is associate with small and medium hydrothermal explosions and landslide (2009–2021). Magma fracking distributions pointed on a new potentially production geothermal reservoir beneath northeast foothills of Mutnovsky volcano (depth range from -4000 to -2000 m, accessible area of 30 km2).

Abstract In contrast of the 1975–76 Tolbachik eruption, the 2012–13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at ~ 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16–20 km to the south of Plosky Tolbachik at 20:31 {UTC} on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975–76 Tolbachik eruption and can be considered as a possible aborted eruption.