Magmatic Systems and the Conditions for Hydrothermal Circulation at Depth in the Klyuchevskoi Volcanic Cluster as Inferred from Observations of Local Seismicity and Thermo-Hydrodynamic Simulation

Abstract

⎯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.

Magma Fracking Beneath Active Volcanoes Based on Seismic Data and Hydrothermal Activity Observations

“…## 2017618050) (these applications discrete fracture systems using seismic and geological data). In these programs, the following criteria are used to select clusters of earthquake hypocenters or production feed zones: (1) proximity in time δt (Frac-Digger only); (2) proximity within the horizontal plane δR; (3) proximity to plane orientation δZ (distance between the object and plane); and (4) minimum number of elements in cluster N. This method has already been tested on the example of the 2012 eruption of Tolbachik volcano [2], the 2000-2016 MEQ data of Koryaksky-Avachinsky volcanic cluster [3][4][5], Paratunsky graben (adjacent to Vilyuchinsky volcano) [6], the Mutnovsky-Gorely volcanic cluster [7], and the Klyuchevkoy group of volcanoes [8]. Note that the methodology of dyke tracking using the Frac-Digger program is presented in detail in Section 3.2.1, "Seismic Data and Method of Plane-Oriented Clusters Identification" [5].…”