From August 14 to 26, 2024, a comprehensive expedition of the Institute of Volcanology and Seismology of the Far Eastern Branch of the Russian Academy of Sciences worked at the Karymsky Volcanic Center (KVC). Research was conducted to restore the hydrochemistry of Karymsky Lake after the catastrophic underwater eruption that occurred in the Academy of Sciences caldera in early January 1996, and a detailed geochemical survey was made of all thermal manifestations in the center. Seismic observations and assessment of the emission of volcanic gas SO2 were carried out, as carried out by the Karymsky volcano, the volume of above-ground CO2 degassing was measured at the thermal sites of the Karymskaya and Academy of Sciences calderas, and samples of spring water were taken to determine the chemical composition and analyze trace elements. Infrared survey and aerial photography of the southern sector of the KVC were carried out.
This publication presents the first results of seismic observations in conjunction with an assessment of the emission of the SO2 volcanic gas, information on the chemical and mineral composition of the springs of the Karymskaya caldera, and aerial photography data of the volcano.

Klyuchevskoy is one of the most powerful active basaltic volcanoes in the world. Information about its eruptions has been known since 1697. This paper describes the summit eruptions of the volcano from 1935 to 1999, and analyzes such eruptions from 1935 to 2024. Between 1935 and 2024 30 summit eruptions occurred: 11 explosive eruptions lasting from 6 to 1110 days and 19 explosive–effusive eruptions lasting from 26 to 1100 days. It was found that paroxysmal phases of eruptive events with ash ascent to the maximum height (15 km above sea level) are characteristic only of explosive–effusive eruptions of the volcano. It was noted that paroxysmal phases of eruptions were observed, as a rule, 6–15 days or 1–2.5 months (rarely 2 days or 7 months) before their end, i.e., an increase in the power of ash ascent from the volcanic crater in some cases led to the emptying of the magma reservoir (for example, the eruption of 1994) and in other cases to the rise of new portions of lava to the daylight surface (for example, the eruptions of 1944 and 1987–1990).

In 2024, explosive eruptions of the Sheveluch, Klyuchevskoy, Bezymianny, and Karymsky volcanoes occurred at Kamchatka, and the Ebeko volcano at the Northern Kurile Islands. On April 26, 2024, a new lava dome, named after the 300 years of the Russian Academy of Sciences began to grow in the area of the Karan old dome on the Stary Sheveluch volcano western slope. Powerful explosive eruptions that destroyed the new dome were observed on August 17–18, September 1–2, and November 7–10, 2024: eruptive columns rose up to 11 km above sea level, ash plumes extended for 2400 km mainly to the northeast and east of the volcano. The summit explosive eruption of the Klyuchevskoy volcano lasted from December 27, 2023 to January 2, 2024: explosions send ash up to 7 km above sea level and ash plumes extended for 230 km to the northwest of the volcano. The paroxysmal explosive eruption of Bezymianny volcano occurred on July 24, 2024: the eruptive cloud rose up to 12 km above sea level, the eruptive and coignimbrite clouds moved, respectively, to the northeast and northwest up to 2500 km from the volcano. The Bezymianny eruption forecast, which was published on the KVERT website, was realized 39 h 40 min later. Explosive activity of the Karymsky volcano was observed from June 20 to November 12, 2024: explosions raised ash up to 6 km above sea level and ash clouds moved for 665 km, mainly to the east and northeast of the volcano. In 2024, 287 explosive events occurred on the Ebeko volcano with ash removal up to 4.5 km above sea level. During the explosive eruptions, the Sheveluch and Bezymianny volcanoes were dangerous for international and local air travel and the Klyuchevskoy, Karymsky, and Ebeko volcanoes were dangerous for local air travel.

This paper describes the chemical composition of the thermal waters discharging on the northwestern slope of the active Ebeko Volcano in the Yuriev River valley. We are using continuous multiyear observations of the evolution of chemical and isotope compositions to estimate the response of volcanic events to the state of the hydrothermal system. It is shown that phreatomagmatic eruptions of the volcano were preceded by a change in the chemical and isotope compositions of thermal waters caused by increased inflow of magmatic volatiles into the system. The springs are observed to show increased concentrations of anion-generating components (chloride, sulfate, and fluorine ions) with concurrent increases in heavier isotopes of oxygen and hydrogen (deuterium) toward “andesitic” water. Recalling that the changes were detected a few months before the eruption, we infer that such geochemical effects can serve as predictive markers when monitoring the state of the volcano.

Mutnovsky Volcano is characterized by predominantly magmatic activity for the last 4 thousand years in the northern sector where the Mutnovsky geothermal field lies. Magmatic activity is identified using the Frac-Digger method based on seismic data as reported by the KB FRC UGS RAS. The most significant sequence of shallow dikes striking northeast has been manifested at the surface by blowing two-phase geothermal wells. Dike emplacement in March 2024 was synchronized with a hydrothermal explosion producing a crater of volume reaching 0.36 million m3 at the place of well 022 (Crater 022+). Unaltered fragments due to the explosion indicate a lithoclastic character in the gas-enriched head of the dike. The bottom of the explosion crater is a hydrothermally altered (opal, zeolite) 160 × 75 m2 in area. The mechanism of the hydrothermal explosion is treated as resulting from hydraulic fracturing by means of a shallow dike, with subsequent increase in pressure in the shallow geothermal reservoir near the well with a closed wellhead control-valve.

The Paratunsky and Verkhne-Paratunsky fields (Kamchatka, Russia) are examples of low-temperature nitrogen (LT N2) geothermal systems that are widespread throughout the world and are believed to have formed as a result of penetration of meteoric water into deep faults and heat mining from host rocks under background heat flow and temperature gradient conditions. However, no one has tested the geologically long-term thermal recharge capability of such systems to be recharged by heat and water under real 3D environmental conditions. A solution to this unsolved problem has been obtained here using specific examples. The two closely spaced reservoirs are 15 km apart, composed of volcanogenic rocks of Eocene-Quaternary age and characterized by shallow permeability reservoirs underlain by extinct volcanic conductive roots, where 60–90 ◦C thermal N2 SO4–Na waters circulate. The Paratunsky reservoir has a 60-year history of intensive exploitation (150–250 kg/s), while the Verkhne-Paratunsky reservoir is just being brought into development. Application of a simple radial-cylindrical (RZ) model to the Verkhne-Paratunsky geothermal system allowed us to show the principal possibility of formation of a circulating hydrothermal system in a structure with a radius of about 15 km and a circulation depth of -3 km within the first thousand years at a temperature of 60 ◦C and a flow rate of 60 kg/s.
Then a three-dimensional numerical (3D) model of the Verkhne- Paratunsky and Paratunsky low-temperature nitrogen geothermal system was constructed, assuming that the upper part of the pre-Cretaceous basement is a permeable conduit surface and the roots of extinct volcanoes provide vertical down-flow recharge and up-flow discharge of this natural heat and mass circulation system. This numerical model covers all significant thermal discharge features, recharge area of the adjacent highlands. Subsequent modeling confirms the possibility of increasing the temperature to 80 ◦C, diluting the initially brine-saturated NaCl permeable reservoirs and maintaining up-flow rate at observed values for thousands of years from the onset of hydrothermal circulation.

The Sheveluch volcano is the northernmost active volcano in Kamchatka. In this work, we describe the activity of the new 300 Years of the RAS lava dome of volcano in 2024–2025. Explosive eruptions of the dome were observed on August 17–18, September 1–2, and November 7–10, 2024: eruptive columns rose up to 9, 8, and 11 km above sea level, respectively, and ash plumes were extended for 2400, 1100, and 3000 km to the east and northeast of the volcano. The results of detailed real-time monitoring of the volcanic eruption are presented using a video surveillance system and various satellite data from The Remote Monitoring of Volcanic Activity in Kamchatka and the Kurile Islands information system (VolSatView, http://kamchatka.volcanoes.smislab.ru).

Unique compositional diversity of volcanic rocks was recently discovered in an active fault zone of the Sredinny Range (Kamchatka) located in the zone of monogenetic volcanism near the Tigil and Oxi volcanoes. The lavas in the zone represent common for SR medium-K, high-K and high-Ti, and also unique for Kamchatka high-LREE and high-Mg varieties. In this contribution, we present new Sr-Nd isotope data for a representative set of lava samples from this area. The isotopic and geochemical characteristics of the majority of selected samples can be explained by the differences in the amount of fluid, fluid sources and melting conditions, proposed earlier for the SR. The high-LREE picritic basalts, however, differ significantly from the other Kamchatka volcanic rocks—their highly unusual high-LREE, high-Li and low-LILE geochemical characteristics combine with the highest 87Sr/86Sr (0.70365) and second-highest εNd (9.9) values ever reported for lavas from the SR. We suggest that they represent the product of melting of the specific SR lithosphere domain that has been metasomatized by melts derived from a strongly degassed slab.