The article provides information about nival-volcanogenic, possibly glacial-volcanogenic, mudflows (lahars) on three streams on the south side of Atlasov Island (Kuril Islands, Russia). The island is an active stratovolcano Alaid, 2339 m asl high. The effusive-explosive eruption of the Alaid volcano began on September 10, 2022 and continues to the present day. Strombolian activity of the apical cone and lava outflow is observed. Lava filled the summit caldera by September 27. The lava flow then crossed the southern part of the caldera crest and began to descend down the erosional depression at the tops of the catchments of three unnamed streams. Photography and satellite images showed the presence of mudflow transformation of stream beds and slopes, and mudflows fan at the mouths of the streams. Analysis of meteorological and volcanological data showed that the formation of lahars was caused by rapid melting of snow/ice under the influence of lava flow and it occurred between September 29 and October 2.

Приводятся данные о состоянии вулкана Эбеко в 2012–2013 гг.: фумарольная активность, состав газов, гидротермальные взрывы на Юго-Восточном фумарольном поле. Обсуждаются причины гидротермальных взрывов. Дается оценка активности вулкана.

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.

The article provides data on explosive eruption from January 29 to June 18, 2009 produced by Ebeko Volcano, Paramushir Island. The eruption was produced from Activnaya funnel in Northern crater. The volcano was continuously sending gas-ash cloud to an altitude of 300 to 1000 m above the crater interrupted by sporadic increase in amount of ash inside the jet and increase in its yield. The volcano produced 3 to 15 events per day sending the columns to an altitude of 500 m to 3.7 km. Ebeko produced phreatic event erupting resurgent ash. Total volume of the erupted materials comprised about 19 thousand of tons. The event was preceded by alteration in chemical composition of fumarole gas and considerable increase in its yield caused by a new fumarole field.

Приводятся сведения о слабом фреатическом извержении вулкана Эбеко на о. Парамушир, которое длилось с 29 января по 18 июня 2009 г. Центр извержения находился в Активной воронке Северного кратера. Изверженные продукты представлены резургентными пеплами. Дана оценка состояния вулкана после извержения на основе данных о мощности тепловой разгрузки, составе и температуре фумарольных газов

The items of information about eruptions activity of Ebeko volcano in 2010-2011 are resulted. In 2010 from eruption funnel of Northern crater there were two weak short-term explosive eruptions. The eruption was phreatic, the cast out products are submitted by resurgent ashes. Volumes of the thrown out material ~ 1.2 t and ~ 95 t accordingly. All eruptions were anticipated by changes in chemical structure of fumarole gases, before eruption of July 2, 2010 the seismic harbingers were observed. In July, 2011 there was a series of hydrothermal explosions on the average crater of a volcano. The morphological changes have bottom and southwest wall of a crater. The maximal range ejection of ashes did not exceed 560 m.

В последние годы поверхностная газо-гидротермальная деятельность в. Эбеко характеризовалась постоянством теплового потока и химического состава вод и фумарольных газов. Активность вулкана неожиданно усилилась 27 января 2005 г. Две мощные парогазовые струи диаметром 5 м образовались в Активной воронке Северного кратера. В июле 2005 г. в нем возникло новое мощное высокотемпературное фумарольное поле. Отмечено изменение в химическом составе фумарольных газов. Для них сделаны расчеты отношений отдельных компонент, являющихся для вулкана геохимическими предвестниками извержений. На основе полученных результатов и самого факта усиления фумарольной деятельности вулкана Эбеко дается среднесрочный прогноз его эксплозивного извержения. Описано загрязнение атмосферы одним из токсичных газов (сероводородом). Ранее считалось, что из-за частых сильных ветров токсичные газы представляют лишь кратковременную угрозу населению г. Северо-Курильск. Показано, что при наличии снежного покрова в периоды повышения активности вулкана Эбеко опасность отравления токсичными газами резко возрастает и имеет постоянный характер как на самом вулкане, так и к районе г. Северо-Курильск

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.

The article presents data on two explosive eruptions produced by Ebeko Volcano 19 to 20 October, 2016 and over the period from November 8, 2016 till the end of August 2017. The latter eruption continues. The material was erupted from three vents: one vent is located in the Active funnel and two vents are at the bottom of Middle crater. The authors analyzed the chemical, mineral, and granulometric compositions of tephra. The studied tephra does not contain magmatic components. The authors classify the eruptions as phreatic. The paper provides the assessment of the composition and volume of gas emission. The gross total volume of the erupted material was estimated to exceed 1.5 million tons.