Klyuchevskoy volcano activity between November 2019 and June 2020

Growth of explosive activity of Ebeko volcano in April–June 2020

The paper presents the results of integrated geophysical observations of the Ebeko Volcano’s activity in late 2018 and early 2019. The instrument complex for observation was located at the Severo-Kurilsk seismic station at a distance of 7.2 km far from the volcanic crater. Three types of response in the vertical component of the electric field of the atmosphere have been distinguished during the drift of eruptive clouds from the Ebeko Volcano’s explosions, which gives evidence for various mechanisms of their occurrence. The registration of infrasonic acoustic signals in the near zone made it possible to estimate the trinitrotoluene equivalent for the strongest explosions, which was calculated to be about 100 kg of trinitrotoluene. The authors have revealed certain regularities in the dynamics of the volumetric activity of radon, associated with variations in meteorological values and hydrological features of the registration point. A long period of its activity and the proximity of the observation point to the crater give reason to suggest Ebeko Volcano to be a natural laboratory for studying the mechanisms of eruptions.

This report provides a brief description of the field work on the Kuril Islands. It was performed within the framework of the R&D theme, projects of the RSF and the RFFR, which are realized in the laboratory of postmagmatic processes of the Institute of Volcanology and Seismology FEB RAS. Hydrological and hydrochemical works were performed on the rivers draining the slopes and thermal fields of the Sinarka, Kuntomintar volcanic massifs (Shiashkotan Island), and the Vernadsky and Karpinsky Ridges (Paramushir Island). The study of the chemical erosion of volcanic islands and the assessment of the hydrothermal export of magmatic volatiles are the goals of this work. Infrared photography was taken and the total flux of volcanic SO2 and diffusion flux of CO2 were measured on thermal fields in the caldera of Golovnin volcano. A detailed hydrogeochemical survey was made on the thermal fields of the Ebeko volcano to study the relationship of volcanic and hydrothermal activity of the volcano. For further analytical work, a large number of water and gas samples were taken and a representative collection of rocks and sediments was collected during the expedition.

The second phase of field work in 2020 on the Alaid Volcano, located on Atlasov Island in the north of the Kuril Island Arc, was carried out on October 2. There was no snow in the crater at the time, and this made it possible to study the deep part of the crater and take samples of rocks and snow. The measurements of the temperature of fumarole gases showed that for the tested fumaroles it varied in the range of 35° to 95° C. Rock samples were also taken from the Svechka Rock and at Cape Shtormovoy. It was found that there is currently no water in Yuryev Creek, located in the west-northwest part of Atlasov Island. The studies carried out have made it possible to obtain new unique information, which will undoubtedly be useful to various researchers of active volcanoes in the Kuril island arc.

Field work in 2020 on the Alaid volcano located on the Atlasov Island in the Kuril island arc was carried out in the coastal zone from Cape Devyatka to Cape Kudryavy. Base camp was located in the site of the former fishing base Devyatka. At the time of the research, the Alaid volcano performed only fumarolic activity. We sampled rocks and fresh water. We also sampled copper, found, as in other slopes of Alaid Volcano, in cracks or in a form of solid covers. We also measured magnetic susceptibility of rocks in their natural manifestations. The unexpected but important outcome of field work was the discovery of a new colony of snails from the Bradybaenidae family, what allows us to confidently say that these snails have survived the eruptions of Alaid Volcano in the XX and XXI centuries.

Isotope-geochemical material for Pliocene-Quaternary volcanoes of the Kamchatka region is generalized on a cartographic basis. The Sr-isotope anomalies of moderate and elevated radiogenicity, geochemically confirmed, are spatially conjugated. This made it possible to interpret these anomalies not only as a reflection of mantle plume material in the composition of volcanic rocks, but also of its hybrid environment, as a consequence of plum-lithosphere remobilization. The presence of multi-directional geochemical trends made it possible to propose the concept of moving boundary values for the composition of indicator rocks of the intraplate type and adakites, which significantly expanded the possibilities of their diagnostics. The isotope-geochemical heterogeneity of basaltoids of the region is generally determined by the peculiarities of concentration of rocks with intraplate and adakite geochemical characteristics, which allows considering the asthenospheric diapirism as the main factor of petrogenesis of Pliocene-Quaternary volcanism in Kamchatka.

The results of monitoring at high-temperature fumarolic fields (Eastern and Western) of Avachinsky volcano in 2013–2020 are presented. Those were visual observations, temperature measurement and gas sampling, supplemented with video surveillance data. In order to identify the relationship between fumarolic activity and deep processes, the analysis of the volcano area seismicity for the specified period was carried out. Two periods of increased seismic activity have been identified. The first period, November 2014 – January 2015, is associated with changes in the character of gas emission, morphology and temperature of Western Fumarole observed in the field, reflected in the ratio of gas fluxes of the two high-temperature fumarolic fields. The second seismic increase, in October – December 2019, was accompanied in the dark by glowing, sometimes by bright flashes in the area of Western Fumarole, and as a result of ground survey in 2020 further changes in its morphology were revealed.

The peculiarity of extrusive rocks of Mendeleev Volcano draws attention of researchers. According to previous research, the Mendeleev Volcano is telescoping caldera, composed of two shafts, the central cone and final extrusion. However, there are no any cuts that characterize the morphological structure of these elements, in the literature. Conducted in 1991, field studies have allowed us to design a more simple circuit of Mendeleev Volcano structure, as well as the study of the cut of Mechnikov Mountain's caldera shaft enabled us to offer the following explanation of the genesis of the extrusion of the Mendeleev Mountain.
Basalts that filled the peripheral focus of Mendeleev Volcano evolved till andesite-dacite by fractional crystallization. Fluid accumulation in the chamber has led to liquid immiscibility of residual magma to dacitic and andesitic compositions. Being thrown out with final explosion they formed a patch of contrast rocks: white dacitic pumices and black andesitic slags. Magma remnants of contrast compositions, losing fluids, were pressed out as andesite-dacite extrusions containing anomalous phenocrysts parageneses.

In the past six decades in Kamchatka it worked great galaxy of scientists (experts), which has developed a number of original methods for monitoring and predicting volcanic eruptions, based on which was issued a number of spectacular short-term forecasts eruptions for volcanoes: Great Tolbachik Fissure in the years 1975-1976, by-Kliuchevskoi in 1983, Shiveluch in 2001, Kizimen in 2009, Bezymiannyi in 2001-2012 and etc. Detailed analysis of the obtained Kamchatka rich experience will enhance the efficiency of forecasting natural disasters.