Variations in the volume of the Kozelskii Glacier in Kamchatka over 1977–2022 are evaluated. The glacier area virtually has not changed over this period; its front has advanced by almost 0.7 km, the volume has decreased by 34.15 ± 6.74 million m3, the surface has dropped by an average of 17.3 m, the cumulative mass balance was –14.70 ± 3.94 m w.e., and the specific average annual balance was –0.33 m w.e./year. The advance of the front line has slowed over the past 10 years and was about 5 m/year.

Received May 26, 2023; revised June 6, 2023; accepted June 27, 2023The change in the volume of the Kozelsky Glacier in Kamchatka for the period 1977–2022 (1977–2015 and 2015–2022) was estimated using historical data and modern DEM. During this period, the area of the glacier did not change much. At the same time, its length increased by about 0.7 km, while the width decreased over its almost whole extent. The volume of the glacier decreased by 34.15 ± 6.74 million m3, and its surface became lower by 17.30 m, on the average. The cumulative mass balance amounted 14.70 ± 3.94 m w.e., and the mean annual value –0.33 m w.e. yr–1. In the last 45 years, the ice loss and redistribution to lower hypsometric levels took place on the Kozelsky Glacier. In 1977–2015, the average area change in the altitude of the glacier surface was equal to –17.84 m, the volume decreased by 35.21 ± 7.20 million m3, the cumulative mass balance amounted –15.16 ± 4.17 m w.e., and the mean annual balance –0.40 m w.e. yr–1. In the period 2015–2022, an elevation of the glacier surface was recorded by 0.59 ± 1.55 m on the average, the volume increased by 1.01 ± 2.65 million m3, the cumulative mass balance amounted to 0.50 ± 1.35 m w.e., and the mean annual balance – to 0.07 m w.e. yr–1. During the last decade, a slowdown in the movement of the glacier front down the valley was recorded. In 2012–2022, the glacier front advanced with a velocity of about 5.2 m/year, while it was 17.9 m/year in 1977–2007, and 20.0 m/year in 2007–2012. The current climatic conditions are not favorable for development of glaciers. In 1977–2022, a trend of the summer air temperature rise was observed with a relatively stable amount of precipitation falling during the cold period. The almost continuous (except 1978–1981) advance of the glacier in 1977–2022 can be explained by the influence of the volcanic factor. A thick surface moraine covers more than 2/3 of the glacier area and, thus, prevents the surface ablation. Increased seismic activity associated with active volcanism promotes the ice movement.

A. Yu. OZEROV*, G. A. KARPOV*, V. A. DROZNIN*, V. N. DVIGALO*, Yu. V. DEMYANCHUK*, V. V. IVANOV*, A. B. BELOUSOV*’, P. P. FIRSTOV**, V. A. GAVRILOV*” , V. V. YASHCHUK” *’, and A. M. OKRUGINA* Institute of Volcanology, Far East Division, Russian Academy of Sciences, PetropavlovskKamchatskiy, 683006 Russia Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Petropavlovsk-Kamchatskiy, 683006 Russia Kamchatka Center for Monitoring Seismic and Volcanic Activity, Petropavlovsk-Kamchats­ kiy, 683006 Russia "** Experimental Seismological Team, Institute of Volcanology, Far East Division, Russian Academy of Sciences, Petropavlovsk-Kamchatskiy, 683006 Russia

Vertical ground displacements at the Mutnovskii Geothermal Field were measured annually during the 2004–2013 period using a network of borehole markers. Three areas have been identified where the vertical displacements were different in character. Positive vertical deformation (2–5 mm/yr) was recorded in the middle of the Dachnyi Area in 2005–2006, giving way to a later stabilization. The North Test Area where the exhaust heat carrier was reinjected did not show any substantial deformation during the 2003–2006 period. This was followed by an uplift in 2006–2008 (6–7 mm/yr) and then by a subsidence (5–8 mm/yr) in 2009–2013. No vertical deformation worth mentioning was recorded in the Verkhne-Mutnovskii Area prior to 2008, but a rapid subsidence began at a rate of 6–18 mm/yr after 2008. We used the TOUGH-FLAC software to analyze vertical ground deformation. This program is used to perform thermo-hydrogeomechanical (THM) modeling based on the previous TOUGH2 model. THM modeling can explain relative vertical deformation during the exploitation of the Mutnovskii Geothermal Field by separating the geothermal field into two compartments by the Osnovnoi fault, as the two have different tectonic settings and petrophysical properties.

In 2001, after a six-year pause in extrusive activity, lava dome growth resumed at Molodoy Shiveluch Volcano. The new period of dome growth (2001–present) has morphological features that were uncommon during the previous periods of the dome formation (1980–1981, 1993–1995): numerous lava lobes and crease structures. Thus, the current dome growth is mostly of an exogenous type with short periods of endogenous growth that occurred in 2003, 2005, and 2010. Geomorphological interpretation of stereo photo images has revealed elements of the dome that are hardly distinguishable in single photographs. We have made detailed descriptions of the dome morphology covering all the dates of the available images. By using photogrammetric processing of aerial photographs, we created Digital Terrain Models and topographic maps of the lava dome and defined its volumes for 2001 (0.19km3), 2003 (0.47km3), 2005 (0.48km3), 2010 (0.54km3), and 2012 (0.63km3). We also defined other morphometric characteristics: absolute and relative heights, as well as the dimensions of the dome and its elements for the investigated period. Taking into account large partial failures of the dome in 2005 (>0.11km3) and 2010 (0.28km3), we suggest that the volume of the extruded material for the whole 1980–2012 period was no less than 1.02km3. The average extrusion rate over the 2001–2012 period exceeded 225,000 m3/day. The transition from endogenous to exogenous dome growth was possibly caused by change in extruded material physical properties due to an increase of SiO2. On the basis of geomorphological analysis of the current lava dome features, we suggest the possible process of the exogenous dome formation at Molodoy Shiveluch. The crease structures detected at Molodoy Shiveluch were classified into three groups according to their shapes: radial, bilaterally symmetrical, and irregular. These crease structures are morphologically similar to those formed at Unzen Volcano during the 1990–1995 eruption. Some revealed morphological features of the crease structures show that the role of gravity is insignificant in their formation. We assume that the crease structures at Molodoy Shiveluch were formed by inner stresses due to thermal and solidification gradients.

This paper presents the results from the detailed analysis of aerial photographs and space images for the Kizimen area, which characterize the geologic and geomorphologic effects of the ongoing eruption over the 2010–2011 period. It is shown that the total volume (>0.5 km3) and total mass (>109 t) of the discharged (resurgent plus juvenile) material makes this eruption the most productive in Kamchatka for the first 12 years of the 21st century. The dominant component (>90%) is juvenile material with andesitic composition. The pyroclastics (tephra, deposits of the juvenile pyroclastic avalanches and incandescent debris avalanches) comprise >0.3 km3and >0.45× 109 t, the lava (a very thick block lava flow 3.052 km long and 2.163 km2 in area) occupies about 0.195 km3 and 0.45 × 109 t. With the exception of the tephra, which fell over an area of about 100000 km2, the rest of the material was accumulated on the Kizimen cone and at its base. The mean discharge rate of juvenile ejecta was about 15 m3/s (29 t/s) for 13 months (November 11, 2010 to December 11, 2011). Appreciable changes also occurred at the near-summit part of the volcano’s cone.

Рис. 4. Положение облака, содержащего диоксид серы, связанного с извержением Толбачика (по спутниковым дан ным AIRS за 29.11.2013г., 02:53 UTC).Концентрация приведена в единицах Добсона (DU) (единица Добсона равна 0.01 мм толщины сжатого слоя озона при 0°C или 2.69 ⋅ 10 20 молекул озона на 1 м 2 ).Штриховая линия -границы спут никового снимка.

This paper presents quantitative estimates of parameters for the Tolbachik Fissure Eruption of 2012–2013 (TFE) for the period between November 27, 2012 and June 5, 2013. It is shown that the eruption was the most violent during the first 2 days (with a mean lava discharge rate of 440 m3/s), when the maximum number of lava vents were active along the entire fissured zone. The rate was decreasing during the subsequent 2 weeks (the mean was 140 m3/s). Lava effusion had been occurring at an almost uniform rate at near 18 m3/s from the later half of December 2012 to June 2013. The eruption was predominantly effusive in character. Six months of activity yielded 0.52 km3 lava to cover an area of 35.23 km2. The volume of pyroclastics within 1.5 km of the new fissured zone did not exceed 0.1 km3. We made maps to show the location of the fissured zone, the main vents, and lava flows on the slope of Ploskii Tolbachik Volcano. It was found that the 1975–1976 collapse pit in the smaller summit caldera of Ploskii Tolbachik has been left nearly intact during the Tolbachik Fissure Eruption of 2012–2013.

Приведены результаты детального анализа аэрофотоснимков и космических изображений района вулкана Кизимен, характеризующие геолого-геоморфологический эффект последствий его продолжающегося извержения в 2010–2011 гг. Показано, что по общему объему (> 0.5 км3) и массе ( 109 т) изверженного (резургентного + ювенильного) вещества оно – самое продуктивное на Камчатке за первые 12 лет XXI века. Доминирует (> 90%) ювенильный материал, отвечающий по составу андезитам. На долю пирокластики (тефра, отложения ювенильных пирокластических лавин и раскаленных обломочных лавин) приходится > 0.3 км3 и > 0.45 ? 109 т лав (очень мощный глыбовый лавовый поток длиной 3.052 км и площадью 2.163 км2) – около 0.195 км3 и 0.45 ? 109 т. За исключением тефры, выпавшей на площади порядка 100 тыс. км2, весь остальной материал был аккумулирован на конусе вулкана Кизимен и у его подножия. Средняя интенсивность выноса ювенильного вещества составила за 13 месяцев (11.11.2010–11.12.2011 гг.) около 15 м3 (29 т/с). Заметные изменения произошли и в привершинной части конуса вулкана.

We consider the results of the 19730–2008 aerial photogeodetic surveys conducted in the famous Geyser Valley of Kamchatka by the Institute of Volcanology (IV) of the Far East Division (FED) of the Russian Academy of Sciences (RAS), in 1973–1993, and by its successor, the Institute of Volcanology and Seismology (IV&S) FED RAS, in 2007–2008, in cooperation with the Chair of Photogrammetry at the Novosibirsk Institute of Engineers in Geodesy, Aerial Photograph Survey and Cartography (to be referred to here by the Russian abbreviation NIIGAiK), in 1973–1985. The aerial survey performed by the IV following Typhoon Elsa in October 1981 identified and recorded the typhoon-induced landslide that was the first to occur during the observation period in the east side of the valley. The measured area of landslide deposits is 28600 m 2 and its volume is 80000 m 3 . An analysis of materials resulting from the July 12, 2007 aerial photograph survey was the basis for an objective evaluation of the impact of the June 3, 2007 catastrophic event in the Geyser Valley, for determining the qualitative and quantitative characteristics of the new landforms, and for a long-term forecast of future hazardous events and processes. It was concluded that the hazardous natural events and processes that have occurred in the past will undoubtedly occur in the future as well. For this reason the Geyser Valley should be constantly monitored using highly accurate geodetic and remote sensing techniques.

Mutnovsky volcano's thermal output (≈1122 MWt with temperatures above 600oC) (B.G. Polyak, 1985, is exceptional for a volcano in repose, and suggests robust magma convection within Mutnovsky's conduit. In summer 2007 helicopter's infra-red (IR) survey was done, thermal surface distribution of the Mutnovsky crater floor and adjacent geothermal field areas were obtained, and thermal heat output of the Mutnovsky volcano currently re-estimated as ≈825 MWt.

Освещены последствия катастрофических событий (большой объемный обвал горного массива, связанные с ним грубообломочная лавина, мощный селевой поток, подпрудное озеро), произошедших в камчатской Долине Гейзеров 3 июня 2007 г. Выявлены и описаны происходящие там в настоящее время опасные процессы и явления. Даны оценка изменений рекреационных ресурсов в Долине Гейзеров после катастрофы и рекомендации по дальнейшему ее использованию в качестве туристического объекта.