The paper reports the appearance of a new crater lake on the Ebeko volcano. There has been no thermal lake within the Northern Crater since mid-2006. The last eruption began on October 19, 2016 and ended on November 19, 2021. The pyroclastic cone of the new crater, which was named Korbut Crater, rose within the Northern Crater. There was strong fumarolic activity in the Korbut crater, which persists today. The lake in the still erupting Korbut crater was first recorded by the authors on a satellite image from September 17, 2021; already on a satellite image from September 25, the crater was dry again. After the end of the Ebeko eruption, due to the intensive flow of fluid with bottom fumaroles and due to a large amount of meteoric precipitation, a lake was formed in the Korbut crater (Sentinel 2 satellite data of December 11, 2021). In January 2022, the authors examined the Korbut crater: the diameters of the lake were 61 and 80 m (latitude and meridian, respectively), the mirror area was 4.5 thousand m2, and water temperature was 43°C. A brief literature review of the existence of thermal lakes on the northern flank of the Ebeko volcano is given.

This article reports new data on the chemical and isotopic composition of volcanic gases and the SO2 flux and the soil CO2 flux from the active Ebeko volcano. Within the time interval of 2003–2021 the volcano erupted in 2009, 2010, 2011, October 2016–November 2021. Volcanic gas composition for 2003–2016, 2021 were obtained by direct sampling from fumaroles. The high-temperature gas (420–529°C) has a composition typical of magmatic gases with C/S atomic ratios <1, HCl content 5–7 mmol/mol; isotopic composition of the volcanic vapor δD ~ –24, δ18O = 2.6–4.9. Geochemical precursors of eruptions have been established: an increase in concentrations of CO2, H2, SO2, HCl; a drop in the C/S ratio up to values of <1, which is characteristic of magmatic gases of the Kuriles; an increase in temperature; heavier values of δD and δ18O in the gas condensates; increasing of the total gas output. А high soil CO2 flux was measured using the accumulation chamber method at two thermal fields (up to 10442 g/m2/day), exceeding the visible discharge (~50 t/day versus ~40 t/day). SO2 flux from the active crater was measured by DOAS instruments in 2020 and 2021: they were 99 ± 28 and 9 ± 2.7 t/day in gas plumes, and 747 ± 220 and 450 ± 130 t/day in ash plumes, respectively. A decrease of SO2 output is associated with the rise of degassed magma before the end of the eruption.

This paper presents results of a specialized analysis applied to deposits reached at site 193 which was drilled during the 19th cruise of the drillship Glomar Challenger in the Pacific Ocean east of the Central Kuril Islands. These data can serve as a basis for the initial phase of future submarine tephrochronologic surveys in the area. Special attention was paid to layers, lenses, and spots of tephra of varying composition and thickness, as well as to sediments having a higher admixture of volcanic glass particles. It was found that at least 8 ashfalls have occurred in the area of site 193, of which 7 took place during the last 115 ka. It is shown that these were more likely related to large and caldera-generating explosive eruptions at volcanic centers in the Kuril Islands. Preliminary dating of these has been carried out. For the first time, a core sample was identified to contain turbidite due to a hypothetical submarine earthquake that occurred in the Early Holocene. We suggest a hypothesis to explain why the sea sediment core samples are disrupted, hypothesizing that thick interbeds of water-rich pyroclastic material of aleuropelite dimension were converted to hydrosols by thixotropy.

Работа посвящена методике восстановления оптических параметров вулканического H2SO4 по данным радиометра AHI спутника Himawari-8. Методика основана на использовании оптических моделей для различных смесей аэрозольных компонентов вулканического облака, представленных пеплом, кристаллами льда, каплями воды и каплями H2SO4. Использование многокомпонентных оптических моделей различного аэрозольного состава позволило оценить оптическую толщину и массовое содержание H2SO4 в сернокислом облаке, образованном после извержения вулкана Карымский 3 ноября 2021 г. Был проведен комплексный анализ спектральных характеристик сернокислого облака в коротковолновом и инфракрасном диапазоне длин волн, по результатам которого установлено, что сернокислое облако преимущественно представляет собой смесь капель H2SO4 и воды.

After a short period of quiescence, in February 2019, Karymsky volcano (Kamchatka Peninsula, Russia) became active. During the month, a large number of moderate explosions were recorded, some of which were preceded with some periodicity by long-period earthquakes with a high degree of similarity of waveforms. The duration of the multiplet events that preceded the explosions ranged from 4 to 70 minutes. The period between earthquakes decreased as the multiplets developed. The amplitude of earthquake records either increased or remained at the same level. The multiplets with higher amplitude of earthquake records preceded the strongest eruptions. The decreasing period between earthquakes is most likely related to the acceleration of magma ascent and an increase in gas pressure in the volcanic channel. If this is true, the absence of long-period earthquakes after the eruption marks a complete release of gas pressure in the volcanic edifice.

There are 30 active volcanoes in the Kamchatka, and several of them are continuously active. In the XX-XXI centuries 17 volcanoes of Kamchatka erupted. During this time, 183 volcanic eruptions occurred, including three catastrophic eruptions (Ksudach, 1907; Bezymianny, 1956; Sheveluch, 1964). Strong explosive eruptions of volcanoes were the most dangerous for human society because they produce in a few hours or days to the atmosphere till 2-3 cubic kilometers of volcanic products. Ash plumes and the clouds, depending on the power of the eruptions, the strength and wind speed, to traveled thousands of kilometers from the volcanoes for several days. Any territory of the Kamchatka Peninsula has repeatedly been exposed to ash falls, the thickness of ash in settlements was from less than 1 mm to 4-5 cm. Strong explosive eruptions of volcanoes Sheveluch, Klyuchevskoy, Bezymianny, Kizimen, Karymsky, Zhupanovsky, Avachinsky, Kambalny were the most dangerous for air travel not only over Kamchatka, but also hundreds of kilometers away from the peninsula.
The strong explosive and effusive eruptions of Sheveluch, Klyuchevskoy, Bezymianny, Kizimen and the other were often accompanied by the formation of hot mud flows (lahars), which sometimes disrupted transport communications (roads, bridges) of nearby settlements.
Scientists of KVERT monitor Kamchatkan volcanoes since 1993. Thanks to satellite monitoring of volcanoes carried out by KVERT, several explosive eruptions were predicted in the XXI century, and early warnings were made to the population about possible ashfalls in settlements and about hazard to aviation.