Magmatic plumbing systems of the Koryakskii–Avacha Volcanic Cluster as inferred from observations of local seismicity and from the regime of adjacent thermal springs

Abstract

⎯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)(2011)(2012)(2013)(2014)(2015)(2016). The geometry of the magma bodies reflects the NF geomechanical conditions (tension and normal faults, S v > > ) at the basement of Koryakskii Volcano dominated by vertical stresses S v , with the maximum horizontal stress S H max 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 60 о , the size is 2 × 2 km 2 , 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

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

“…Conceptual TOUGH2 modeling was used to understand and explain the mechanism of the formation of the hydrothermal system beneath northern slope of Koryaksky Volcano [4,5]. For this purpose, the following terms were found to be crucial in this model: (1) heat sources of 20 MW/km 3 (340 MW total in 17 km 3 of reservoir rocks) and gas (CO 2 ) sources of 10 g/s/km 3 acting during 7000 years in the zones of magma injections; and (2) cold water recharge of 580 kg/s through the volcanic funnel to the deep dyke injection area.…”

“…Plane-oriented clusters of 5160 seismic events from data of the Kamchatka Branch Federal Research Center United Geophysical Survey Russia Academy of Sciences (KB FRC UGS RAS) of 01.2000-07.2016) below Koryaksky and Avachinsky volcanoes were used to identify magma injection zones [4,5]. Cluster identification was carried out using our Frac-Digger program.…”

“…To recover the sequence of magma injections in the area of the Klyuchevskoy Volcanic Cluster, we used a catalog containing data of seismic monitoring at 19 seismic stations operated by the KB FRC UGS RAS for the 2000-2017 period (the total number of earthquakes that have been recorded between January 1, 2000 and August 23, 2017 is 122,451). The method that we used to identify plane-oriented earthquake clusters and fitting planes using the Frac-Digger software was described in [2][3][4][5]. The relevant calculated plane patches are interpreted as zones of magma emplacement in the form of dykes and sills.…”

“…The Koryaksky Narzan CO 2 -reach thermal springs (12-14 • C) and Isotovsky thermal springs (40-50 • C) are located in a north sector of Koryaksky volcano, where magma injections have taken place since 2008 [4,5]. We have been doing continuous temperature monitoring in Isotovsky spring (IS) since 2010 and in Koryaksky Narzan springs (KN1 and KN2) since 2017.…”

“…## 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].…”