Alunite-group minerals from various post-volcanic occurrences within the Kuril-Kamchatka suprasubduction zone, related to Alaid, Bolshoy Semiachik, Mutnovsky and Shiveluch volcanoes and Evevpenta and Vasilevo epithermal gold-silver ore occurrences, have been characterized by the combination of analytical techniques: electron-probe microanalysis, powder X-ray diffraction, and Raman spectroscopy. As a result, jarosite, alunite, natrojarosite, natroalunite and hydroniumjarosite have been found, among which natroalunite and jarosite being the most widespread. These minerals show strong genetic relation to K- and Na-feldspar, pyrite, and hematite. By chemical composition, they show a wide range of ratios for monovalent cations K/ƩM+. Regarding trivalent cations or Fe/(Fe + Al) ratio, both Fe3+- and Al-members are observed as well as rare varieties with intermediate Fe/(Fe + Al) ratios as 0.00–0.32 and 0.72–1.00. The alunite-group minerals from Shiveluch volcano contain Mg impurity up to 0.2 apfu, which is associated with the high Mg content of the host volcanic rocks (dacites and tephra). In individual samples Ca and P impurity is observed, substitution occurs according to the scheme SO_4^2 - + A+ ⇔ PO_4^3 - + A2+. For the first time for the alunite-group of the Kuril-Kamchatka zone, an admixture of hydroxonium (H3O)+ in the position of a monovalent cation was determined by Raman spectroscopy.
The typicality of successful forecasting was shown for a set of anomalies described in detail earlier in a result of constructing and analyzing the generalized vicinity of a large earthquake, provided a sufficient number of weak events have been recorded in the source zone of an impending large earthquake. The presence of typical anomalies is shown for Kamchatka MW 8.8 earthquakes of 2025 and its large foreshocks and aftershocks. However, for the Kamchatka earthquake, the development of predicted anomalies is masked by the aftershock sequence of its large foreshock. Several features of the 2025 Kamchatka earthquake are noted. The area of the greatest slip for this event overlaps the source zone of the great earthquake of 1952, which raises the question of a possible deficit of displacements along the subduction zone accumulated from 1952 to 2025. Possible refinements of the earthquake prediction algorithm based on typical anomalies are discussed.
February 2, 2025 marked the 25th anniversary since the start of the Monitoring of Volcanic Activity project conducted by the Kamchatka Branch (KB) of the Geophysical Survey (GS) of the Russian Academy of Sciences (RAS). At present time the studies are being conducted in near real time in four directions: (1) seismicity monitoring, (2) visual and video observations, (3) satellite-based monitoring, and (4) infrasound control. The daily work conducted by the Kamchatka Branch to acquire, to process, and to present the information on volcanic activity enables timely and reasonable assessment of the state of volcanoes, yielding conclusions as to possible developments of volcanic activity. The monitoring results are daily published in the factual database “Activity of Kamchatka Volcanoes”. The original variant of the database using pages in the html format did not envisage full-scale research using the stored observation and processing results; for this reason a new database was developed in 2014 for the Eruptions of Volcanoes in Kamchatka and on the Kuril Islands system, in addition to a package of program modules for data processing. The observation and processing results systematized for the 25 years of this work provided for and helped achieve successes in dealing with problems arising in short-term prediction of strong paroxysmal eruptions on Bezymianny, Klyuchevskoi, and Kizimen volcanoes. For the case of such rarely erupting volcanoes as, e.g., Koryaksky, Avachinsky, Mutnovsky, Gorely, Plosky Tolbachik, and Kambalny, the work involved recording and systematizing seismic and other geophysical data, which will contribute to a better assessment of their volcanic hazard in the future.
This analysis of the general processes in the localized migration of lithium from the mantle according to the Romanyuk–Tkachev model as the ultimate mutual interaction between mantle plumes in Northeast Asia and in the Mongolia–Okhotsk slab through intermediate upper crustal magma chambers rests on the examination of mutual locations of intrusive bodies in the basement and in the sedimentary cover of the Siberian craton and of localization regions (as proved by drilling) containing commercial rare-metal brines with anomalously high concentrations of lithium in the natural reservoirs of the zone of retarded water exchange in the sedimentary cover of the major Angara–Lena artesian basin. It is shown how the region of brine occurrence that has anomalous lithium concentrations overlies in space the ring anomaly formed by the emplacement of a large pluton of the (hypothetical) Paleoproterozoic Baikal–Taimyr orogenic belt in the Early Proterozoic basement. On the other hand, a group of large deposits of lithium-bearing brines in the sedimentary cover (an analogue of an “ore field”) localizes in the band between the apical part of the giant Usolsky Sill to the west and the Baikal-Patomsky Folded Region (BPFR) foreland to the east. We are discussing the likely role played by large paleohydrothermal systems of magma bodies in the formation of lithium haloes, in the process of its subsequent transfer of hydrothermal fluids, and concentration in naturally occurring brines beneath thick deposits of Cambrian salts.
A three-dimensional numerical thermohydrodynamic model of the Mutnovsky magma–hydrothermal system has been developed based on a comprehensive hydrogeological analysis. The model was implemented using TOUGH2 software with the EWASG state module. The study was conducted in two stages. The first stage simulated the natural state of the system driven only by the conduction heat flow (60 mW/m2), which proved insufficient to account for the observed high temperatures of thermal manifestations. The second stage incorporated additional heat sources of magmatic origin, spatially constrained by Frac-Digger analysis of microearthquakes data (2013‒2025). The model with magmatic heat sources (total power 416 MW) shows good match with field data regarding the temperature and flow rate of the main thermal features. The results support the concept of hydrothermal circulation involving infiltration of meteoric water through the volcanic edifice, lateral transit and heating at depth, and subsequent ascent and discharge along fault zones.
The distribution and orientation of regional seismogenic faults of Kamchatka are calculated by Frac-Digger method based on seismic data catalogs of the Kamchatka Branch of the Federal Research Center United Geophysical Survey, Russian Academy of Sciences. The analysis of Mohr–Coulomb diagrams shows three main geomechanical states, when the regional seismogenic faults can be active: NWW horizontal extention at an azimuth of 300°, horizontal radial extention, and horizontal radial compression. Hydrothermal explosions occur, when the pore pressure exceeds the stress values in the rock mass.
The Verkhne Paratunsky thermal springs are the large natural discharge zone of the Verkhne Paratunsky low-temperature nitrogen geothermal field (Kamchatka, Russia). Their hydrothermal and hydrogeochemical history, as well as their discharge conditions, were analyzed based on previous (1966–1996) and renewed (2024–2025) monitoring of the spring regime. The experimental and operational releases at the Verkhne Paratunsky geothermal field in 1975–1984 led to a significant change in the discharge parameters: a decrease in the maximum temperature of the springs from 67 to 46°C and a decrease in the total mineralization (a 2‒2.5-fold decrease in Cl and SO4), while the flow rates of the entrained springs (3.5‒8.2 L/s) are close to the initial values before the start of tests. The flow tests carried out at the Verkhne Paratunsky geothermal field in 1975‒1984 led to a significant change in the discharge parameters: a decrease in the maximum temperature of the main springs from 70 to 30–35°C, a decrease in the flow rate from 7.7 to 2.9 kg/s, and a decrease in the mineralization by two times or more (all in average annual terms). By 2025, the flow rates of the main captured springs had recovered to 5 kg/s, the temperature to 49°C, and the mineralization to 50–65
Highly concentrated Cl–Mg–Ca brines with a salinity of up to 700 g/L of the Siberian Platform contain economic concentrations of valuable strategically important elements (Li), but are challenged due to salt deposition in the wellbore. To solve this task, we used the TOUGH2 family software for modeling the multiphase non-isothermal geofiltration in a fractured-porous medium taking into account the chemical interaction of phases, which was supplemented by an EWASG-CACL2 state module for the description (density, viscosity, and enthalpy) of the CaCl2 brine with a mass concentration ranging from 0.25 to the maximum saturation (>0.6) at temperatures of 0–50°C. The CaCl2 brine was extracted by a single production well with a submersible pump from the target reservoir in TOUGH2-EWASG-CACL2 modeling. The filtration-capacity and thermophysical parameters, as well as the geometry of the target reservoir and the well, were given as synthetic in a range of possible change according to geological exploration data in the south of the Siberian Platform. A potential transition mechanism of the well to stable operation mode is identified as a result of the production well modeling. The first operation stage exhibits a simultaneous growth (up to 86
Based on integrated geological and structural–geophysical studies, we show that the discharge of thermal waters at the Pauzhetka geothermal field is confined to circular tectono-magmatic blocks. We have resolved the essential issue concerning the source of thermal supply to the Pauzhetka geothermal system: a horizon of higher conductivity has been identified at depths between 3.5 and 8 km between the crystalline and the terrigenous basement for the heat flow which is ascending from beneath the Kambalny volcanic range. These results allow us to pass to the consideration of the next problem, namely, a study of the geological structure between the source of thermal supply and the region of discharge for vapor-rich hydrothermal fluids.
This paper presents results from a study of a monogenic cone situated in the Khalaktyrksky beach, Avachinsky, Kamchatka. We used georadar surveying methods to reconstruct the paleo-relief of the monogenic cone and to estimate the thickness of the overlain sediments. Discontinuities are marked by higher values of the spatial distribution for subsoil carbon dioxide in combination with the deformations as detected by the georadar. The data provide evidence of a long-continued degassing from the lavas of the monogenic cone and of activity shown by the discontinuities in the Avachinsky graben of the Malko–Petropavlovsk zone of transverse dislocations.
The Paratunka and Verkhny Paratunsky deposits (Kamchatka, Russia) are examples of worldwide widespread low-temperature nitrogen (LT N2) geothermal systems. The Paratunka geothermal fields are located 15 km apart, composed of the Eocene–Quaternary volcanic rocks, and characterized by shallow permeable reservoirs with deep conductive roots inherited from extinct volcanoes with circulating SO4–Na nitrogen thermal waters of 60‒90°C. The Paratunka reservoir has a 60-year history of intense exploitation (150‒250 kg/s), whereas the Verkhny Paratunsky reservoir is just being commissioned. A 3D numerical thermohydrodynamic model is developed for the Verkhny Paratunsky and Paratunka LT N2 geothermal system (Kiryukhin et al., 2025), which suggests that the top of the pre-Cretaceous basement is permeable, whereas the roots of extinct volcanoes are the channels for thermal fluid upflows and thermal spring discharge. This numerical model also includes a water recharge area from adjacent highlands. The feasibility of exploiting a potential deep reservoir confined to the structural surface of the pre-Cretaceous basement top (an area of 270 km2) for heat supply and using the binary technologies for electric power generation is confirmed. According to numerical modeling results, the possible initial power generation is estimated at 32.3 MWe.
Magmatic activity beneath Shiveluch volcano in 2000–2023 was manifested in the injection of dykes and sills (detected by the Frac-Digger method) with increased concentration in the depth ranges from –1 to +1 km, and from –3 to –2.5 km and NNE striking of dykes toward to Klyuchevskoy volcano. Further seismic lineament analysis reveals a zone of NNE striking trans-volcanic dykes that include more than a half of the total 198K micro-earthquakes recorded in North Group of Volcanoes (NGV), extended under volcanoes into 120 km length (dip angle 79 degrees and dip azimuth of 299°). A regional deep seismogenic fault beneath (dip angle 81 degrees and dip azimuth of 296°) at open mode NF geomechanical conditions, and enormous cold spring discharge (12.3 m3/s) are also hosted in this zone, thus, along with other geological and petrological evidences, it may be defined as NGV rift zone. In many cases (Oct. 28, 2010, Dec. 03, 2013, Dec. 30, 2018, Apr. 10, 2023) paroxysmal eruptions of Shiveluch volcano were preceded by seismic activity in the deep magma chamber of Klyuchevskoy volcano, that’s supposed to be source of trans-volcanic dykes originating from Klyuchevskoy to Shiveluch along NGV rift zone.
This paper presents focal mechanism solutions for large volcano-tectonic earthquakes (VTE) at three Kamchatka volcanoes: Shiveluch, Klyuchevskoi, and Plosky Tolbachik followed by comparison between the results in order to distinguish between the principal and the auxiliary nodal plane. The data set included digital seismograms of VTEs not below energy class 7 and depths of focus between zero and 30 km. The solutions were based on the polarities of P-wave first motions using the FPFIT program algorithm. Comparison between the strikes of the first and second nodal planes for large VTEs on each of the three volcanoes has not been sufficient to find the principal plane. Comparison between the dip angles of the first and second nodal planes for large VTEs on each of the three volcanoes and comparison of directions of motion on the first and second planes has enabled us to identify the first nodal plane as the principal and the second nodal plane as the auxiliary.
Understanding the frequency, dispersal areas, and volumes of tephra fall deposits is essential for assessing related hazards and estimating magma output rates. At the same time, deriving quantitative eruption parameters is often hindered by limited field data on eruptive deposits and, in island-arc settings, by the dispersal of airborne tephra over the sea, where mapping depends on the availability of sediment cores. For frequently erupting volcanoes, obtaining volume estimates are especially challenging because of difficulties in field mapping of numerous and often similar looking tephra fall deposits. In this paper, we present newly calculated conservative estimates of dispersal areas, tephra volumes, and eruption magnitudes for Avachinsky volcano (Kamchatka, NW Pacific), one of the most active and hazardous Holocene volcanoes, located close to the Petropavlovsk-Kamchatsky–Elizovo urban area. Our estimates are based on a compilation of published isopach maps and tephra occurrence sites, complemented by new data, and on a systematic approach to tephra volumes calculations. This research provides a solid basis for future efforts to define the Avachinsky magma production rate and to improve hazard modeling.
This paper presents the results of a comprehensive study of the 2022 eruption of Alaid volcano, which occurred from September 15 to December 1, 2022 the work is based on field observations conducted in 2023 and 2025 using unmanned aerial vehicles (including those equipped with thermal imagers), as well as on laboratory studies of the petrographic and geochemical composition of the eruption products. It was established that as a result of the eruption, the volcano’s crater was completely filled by a lava flow, with a volume estimated at no less than 0.04 km3 and a thickness exceeding 20 m in the near-crater part. A new scoria cone, 350–370 m in diameter and at least 60 m high, composed of tephra, formed in the southern part of the crater. The eruption products are homogeneous high-alumina trachybasalts with a high-potassium signature. A comparison of the composition of the 2022 eruption rocks with products from previous historical eruptions was carried out, thereby refining existing geochemical trends. Thermal imaging surveys, as well as direct temperature measurements, recorded a significant decrease in temperature in the crater zone from >550°C in 2023 to 300°C in 2025, with fumarolic activity persisting locally. The lahar depositional cone in the Cape Devyatka area was studied, where stabilization of the coastline is currently observed.
Sheveluch Volcano is one of the most productive volcanoes in Kamchatka, characterized during the Holocene by alternating periods of predominantly extrusive and explosive activity. New data on the volumetric parameters of fine ash emissions have been obtained, indicating that the mass of erupted material of dacitic composition during a single moderate-strength eruption can exceed 2 million tons. In those years when gas and ash cloud eruptions were particularly frequent (sometimes more than twenty per month), the total mass of fine dacitic ash can be comparable to the annual discharge of andesitic material (extrusive lavas and tephra), providing a new perspective on the genesis of andesites.
On August 3, 2025, a few days after a major Mw 8.8 earthquake struck southern Kamchatka, the first historically documented eruption of Krasheninnikov volcano began in the central part of the Eastern Kamchatkan Volcanic Front. During August and September 2025, we carried out three weeks of field observations of the ongoing activity. The eruption was dominated by lava effusion from three vents aligned along a submeridional fissure zone in the summit area of the Northern Cone and was accompanied only by moderate explosive activity. Based on field observations, we identified and characterized the extent and volumes of four distinct lava flows. Drone-based imagery and video allowed determination of the vent locations feeding each flow. By the end of September, the total area of lava flows was estimated at ∼2.5 km2, with an eruptive volume of minimum 0.025 km3. Analyses of 11 samples of lava and volcanic bombs erupted during the first two months show that the products are moderate-K dacites (SiO2 = 64.9–65.7 wt
Kurgantepa is a multilayered ancient settlement lying in the Urgut Area of the Samarkand Region. It consists of ruins of the center of a rustak (rural district) in the Sogd during early medieval times. The settlement is identified to be the same as the center of rustak Sanjarfagn. It was shown that the population center which was formerly in the territory of the modern Kurgantepa hill is the classic threefold structure of a medieval city: the ark (the citadel), shakhristan (the inner city), and rabad (the suburbs). The archeological excavations which were carried out there in 2022–2024 revealed architectural remains interpreted as a Zoroastrian temple. Its monumental structure, the presence of columns, decorated walls, and the altar, as well as the ritual orientation of internal furnishings, all point to a sacral destination of the building. One of the more interesting features in the temple consists in traces of destruction whose morphology indicates a strong seismic excitation. The study of these deformations, including failures and displacements of fragments of structural elements and the collapses of arch systems, provide data from which to reconstruct the parameters of a possible mediaeval earthquake (local seismic intensity and the direction to the epicentral zone), as well as to expand our knowledge of the region’s earthquake history.
The results of multiyear observations were used to characterize the volcanic hydrothermal systems containing horizons of hyper-acid waters of SO4–Cl or Cl–SO4 composition (ASC-waters) on five islands (Paramushir, Shiashkotan, Urup, Iturup, and Kunashir). We used physicochemical parameters and the macrocomponent composition of the thermal waters to develop an additional classification. Depending on the conditions of percolation and discharge we identified three groups of ASC waters: (a) classical of Al–Fe–SO4–Cl composition, (b) those diluted with groundwater of Ca–Cl–SO4(SO4–Cl) composition, and (c) those mixed with deep thermal waters of Na–Cl–SO4 composition. These groups differ in pH, temperature, salinity, and in the SO4/Cl/F and (Na + K)/(Ca + Mg)/(Al + Fe) ratios. The first group of classical hyper-acid waters of SO4–Cl composition includes the springs at Ebeko Volcano (Paramushir) and at Baransky Volcano (Iturup) whose cation compositions are dominated by Al and Fe. The second group, which is diluted with cold groundwater, includes the thermal waters discharged on the slopes of Sinarka Volcano (Shiashkotan) and Berg Volcano (Kunashir). The third group which is mixed with sodium chloride waters includes the springs at Mendeleev and Golovnin volcanoes (Kunashir). The cation composition of all ASC waters studied on the Kuril Islands is equivalent to less than 10 grams of rock dissolved in one liter of water.
This paper presents data on the contents of metals (Zn, Mn, Cu, Ni, Cr, Pb, and Cd) in ash, soils, higher plants, and marine brown algae of the northeastern part of Paramushir Island, which were collected in June 2024. The analysis revealed excesses of maximum permissible concentrations of heavy metals in soils for the gross forms Zn, Cu, and Cd, for the mobile forms Mn, Zn, Cu, Pb, and Cd, in vegetation, Zn, Mn, Cu, Ni, Cr, and Cd, and in algae, Cd. A comprehensive ecological and geochemical assessment of the state of the soil and vegetation cover of the city and the coastal zone of the island revealed their pollution from low to extremely high levels. At the same time, the average value of the total pollution indicator (Zc) for city soils was 14.4; it was 15.8 for higher plants and 4.8 for brown algae. Considering the small area of Severo-Kurilsk, the population that has not exceeded 3000 people in the last 20 years, and the weak economic and industrial activity, it should be assumed that at present a significant contribution to the chemical pollution of the studied territories is made by natural sources of heavy metals entering the components of the environment. In the areas affected by the ashfalls of the eruptions of the Ebeko volcano, increased concentrations of some elements in the soil and vegetation cover are recorded.
