An analysis of local seismicity within the Klyuchevskoi Volcanic Cluster and Shiveluch Volcano for the period 2000–2017 revealed a sequence of plane-oriented earthquake clusters that are interpreted here as the emplacement of dikes and sills (magmatic fracking). The geometry of magma bodies reflects the geomechanical conditions in volcanic plumbing systems and at the bases of the volcanoes. Magmatic fracking within active magmatic plumbing systems results in the formation of permeable reservoirs whose vertical extent can reach 35 km (Klyuchevskoi) and can be as wide as 15 km across (Shiveluch), depending on the geomechanical condition of the host rocks. These reservoirs will be the arena of subsequent hydrothermal circulation, producing geothermal and ore fields, as well as hydrocarbon fields. TOUGH2-EOS1sc simulation tools were used to estimate the conditions for the formation of hydrothermal reservoirs at temperatures below 1200°С and pressures below 1000 bars.

An analysis of local seismicity within the Avacha–Koryakskii Volcanic Cluster during the 2000–2016 period revealed a sequence of plane-oriented earthquake clusters that we interpret as a process of dike and sill emplacement. The highest magmatic activity occurred in timing with the 2008–2009 steam–gas eruption of Koryakskii Volcano, with magma injection moving afterwards into the cone of Avacha Volcano (2010–2016). The geometry of the magma bodies reflects the NF geomechanical conditions (tension and normal faults, Sv >SHmax >Shmin ) at the basement of Koryakskii Volcano dominated by vertical stresses Sv, with the maximum horizontal stress SHmax pointing north. A CFRAC simulation of magma injection into a fissure under conditions that are typical of those in the basement of Koryakskii Volcano (the angle of dip is 60о, the size is 2 × 2 km2, and the depth is –4 km abs.) showed that when the magma discharge is maintained at the level of 20000 kg/s during 24 hours the fissure separation increases to reach 0.3 m and the magma injection is accompanied by shear movements that occur at a rate as high as 2 × 10–3 m/s, thus corresponding to the conditions of local seismic events with Mw below 4.5. We are thus able to conclude that the use of planeoriented clusters of earthquakes for identification of magma emplacement events is a physically sound procedure. The August 2, 2011 seismicity increase in the area of the Izotovskii hot spring (7 km from the summit of Koryakskii Volcano), which is interpreted as the emplacement of a dike, has been confirmed by an increase in the spring temperature by 10–12°С during the period from October 2011 to July 2012.

A conceptual model of the thermal and water recharge of the Ketkinsky geothermal field as a product of magma and water injection from the Koryaksky volcano located 24 km apart was proposed. A digital hydrogeological model of the Ketkinsky geothermal field was developed in the volume of 7 km x 5 km x 2.5 km (from the topographic surface), it includes the space drilled by exploration and production wells. The model is based on an analysis of 3D distributions of temperature, pressure, salinity and CH4 content, geometrization of productive faults and well productivity characteristics. The geofiltration space was zoned in the model with separation of
deep and shallow productive geothermal reservoirs, the area of deep thermal fluid upflow in the SSE part of the model base and the area of hidden thermal water discharge at the ground surface.
A natural state inversion iTOUGH2-EWASG simulation was performed to estimate the deep thermal water upflow and permeability of productive geothermal reservoirs. The deep thermal water upflow is estimated to be about 10 kg/s, the permeability is estimated to be 190 mD (shallow productive reservoir) and 35 mD (deep productive reservoir). Inverse iTOUGH2-EWASG modeling of the hydrodynamic operating history of 1989–2020 was used to estimate the compressibility of the productive geothermal reservoirs: the compressibility of the deep reservoir is estimated at 7.16E-10 Pa???? 1, the shallow reservoir at 4.14E-07 Pa???? 1. Direct iTOUGH2-EWASG modeling with the above parameters reproduces the history of salinity and temperature changes in production wells.
Forecast modeling of existing producing wells #23, K6, K01, K5 operation for 25 years with application of submersible pumps at immersion depth of 70 m confirms the possibility of their sustainable operation with total flow rate not less than 14.2 kg/s, adding four producing wells may yield to 54.3 kg/s with retaining of produced water quality (temperature, gas content of CH4, salinity).
The use of submersible pumps and reinjection can significantly increase the reserves of Ketkinsky field to 165–175 kg/s of 70–80 ◦C and 60–70 g/s of CH4. Additional increase in reserves may be obtained by drilling the already known thermal anomaly in the SSE sector of the field and in the SWW foothills of Koryaksky volcano.

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).