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.

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.

Avachinsky volcano (Kamchatka, Russia) is an active andesite volcano that poses a significant threat to nearby settlements. There is a high probability of it erupting in the near future. A project to create a pilot volcanological research ground for monitoring the state of the volcano and forecasting eruption scenarios is presented.