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.

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.

At the beginning of the XXI century, increased eruptive activity of the largest volcanoes of the Northern group of Kamchatka is observed: Sheveluch, Klyuchevskoy, Bezymianny and Tolbachinskay fissure zone. The features of growth of andesitic Sheveluch volcano extrusive dome are noted: the height of the dome has reached 600 m during 38 years of almost continuous eruptive activity. After an eight-year period of relative rest, nine terminal eruptions and two lateral breakthroughs of the Klyuchevskoy basalt volcano occurred. Explosive-effusive eruptions of the andesitic Bezymianny volcano were observed almost annually. After 36 years of rest, a new eruption occurred in the Tolbachinsky regional fissure zone.

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.