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.
An Erratum to this paper has been published: https://doi.org/10.1134/S0742046326550014
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.
