Horváth Á, Carr J.L., Girina O.A., Wu D.L., Bril A.A., Mazurov A.A., Melnikov D.V., Hoshyaripour G.A., Buehler S.A. Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology // Atmospheric Chemistry and Physics. 2021. Vol. 21. Vol. 16. P. 12189-12206. https://doi.org/10.5194/acp-21-12189-2021, 2021.
A geometric technique is introduced to estimate the height of volcanic eruption columns using the generally discarded near-limb portion of geostationary imagery. Such oblique observations facilitate a height-by-angle estimation method by offering close-to-orthogonal side views of eruption columns protruding from the Earth ellipsoid. Coverage is restricted to daytime point estimates in the immediate vicinity of the vent, which nevertheless can provide complementary constraints on source conditions for the modeling of near-field plume evolution. The technique is best suited to strong eruption columns with minimal tilting in the radial direction. For weak eruptions with severely bent plumes or eruptions with expanded umbrella clouds the radial tilt/expansion has to be corrected for either visually or using ancillary wind profiles. Validation on a large set of mountain peaks indicates a typical height uncertainty of ±500 m for near-vertical eruption columns, which compares favorably with the accuracy of the common temperature method.
Horváth Á, Girina O.A., Carr J.L., Wu D.L., Bril A.A., Mazurov A.A., Melnikov D.V., Hoshyaripour G.A., Buehler S.A. Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 2: Case studies // Atmospheric Chemistry and Physics. 2021. Vol. 21. Vol. 16. P. 12207-12226. https://doi.org/10.5194/acp-21-12207-2021.
In a companion paper (Horváth et al., 2021), we introduced a new technique to estimate volcanic eruption column height from extremely oblique near-limb geostationary views. The current paper demonstrates and validates the technique in a number of recent eruptions, ranging from ones with weak columnar plumes to subplinian events with massive umbrella clouds and overshooting tops that penetrate the stratosphere. Due to its purely geometric nature, the new method is shown to be unaffected by the limitations of the traditional brightness temperature method, such as height underestimation in subpixel and semitransparent plumes, ambiguous solutions near the tropopause temperature inversion, or the lack of solutions in undercooled plumes. The side view height estimates were in good agreement with plume heights derived from ground-based video and satellite stereo observations, suggesting they can be a useful complement to established techniques.
Korolev S.P., Sorokin A.A., Urmanov I.P., Kamaev A., Girina O.A. Classification of Video Observation Data for Volcanic Activity Monitoring Using Computer Vision and Modern Neural NetWorks (on Klyuchevskoy Volcano Example) // Remote Sensing. 2021. Vol. 13. Vol. 23. № 4747. P. 1-20. https://doi.org/10.3390/rs13234747.
Currently, video observation systems are actively used for volcano activity monitoring. Video cameras allow us to remotely assess the state of a dangerous natural object and to detect thermal anomalies if technical capabilities are available. However, continuous use of visible band cameras instead of special tools (for example, thermal cameras), produces large number of images, that require the application of special algorithms both for preliminary filtering out the images with area of interest hidden due to weather or illumination conditions, and for volcano activity detection. Existing algorithms use preselected regions of interest in the frame for analysis. This region could be changed occasionally to observe events in a specific area of the volcano. It is a problem to set it in advance and keep it up to date, especially for an observation network with multiple cameras. The accumulated perennial archives of images with documented eruptions allow us to use modern deep learning technologies for whole frame analysis to solve the specified task. The article presents the development of algorithms to classify volcano images produced by video observation systems. The focus is on developing the algorithms to create a labelled dataset from an unstructured archive using existing and authors proposed techniques. The developed solution was tested using the archive of the video observation system for the volcanoes of Kamchatka, in particular the observation data for the Klyuchevskoy volcano. The tests show the high efficiency of the use of convolutional neural networks in volcano image classification, and the accuracy of classification achieved 91%. The resulting dataset consisting of 15,000 images and labelled in three classes of scenes is the first dataset of this kind of Kamchatka volcanoes. It can be used to develop systems for monitoring other stratovolcanoes that occupy most of the video frame.
Taran Yuri, Kalacheva Elena, Dvigalo Viktor, Melnikov Dmitri, Voloshina Ekaterina Evolution of the crater lake of Maly Semyachik volcano, Kamchatka (1965–2020) // Journal of Volcanology and Geothermal Research. 2021. Vol. 418. P. 107351 doi: 10.1016/j.jvolgeores.2021.107351.
Significant variations in temperature, water chemistry and volume of the lake in the crater of Maly Semyachik volcano, Kamchatka, in 1965–2020 can be divided in three main stages. The first stage, until about the mid-1980s, was characterized by intense volcanic-hydrothermal activity, high (above 40 °C) temperature, high salinity (up to 40 g/l) and an increase in the level (and volume) of the lake. During the second stage, which lasted 25–30 years, since the mid-1980s until the mid-2000s, the lake cooled down, until freezing in winter, the mineralization decreased (up to 1.6 g/l), and the volume of the lake remained almost constant. After the mid-2000s until present, there is a period of activation of the Maly Semyachik volcano, which is expressed in an increase in temperature, mineralization and a sharp increase in the volume of the crater lake. The water balance of the lake and the input and composition of the thermal acid chloride solution are estimated based on the analysis of changes in chemical and physical parameters over time, using a box model.
Zelenski M., Simakin A., Taran Yu., Kamenetsky V.S., Malik N.A. Partitioning of elements between high-temperature, low-density aqueous ﬂuid and silicate melt as derived from volcanic gas geochemistry // Geochimica et Cosmochimica Acta. 2021. Vol. 295. P. 112-134. https://doi.org/10.1016/j.gca.2020.12.011.
By comparing high-quality volcanic gas and whole rock compositions, we calculated the apparent (observed) mass partition coeﬃcients Kd* for 58 elements on six basaltic volcanoes located in arc and rift/hotspot settings. The inferred Kd* vary from � 1100 for sulfur to 0.0001 for zirconium, i.e., within seven orders of magnitude. Only 14 elements have Kd* > 1, including highly volatile S, Se, Te and halogens, as well as Tl, Re, Os, Bi, Cd, Au, In and As. Alkali metals have Kd* in the rangefrom 0.1 for Cs to 0.01 for Na. Partition coeﬃcients of other rock-forming elements are <0.001. The partition coeﬃcients for elements depend on element speciation and concentrations of ligand-forming elements in the gas such as sulfur and chlorine.
Elements transported in the gas predominantly as halides have higher partition coeﬃcients in HCl-rich arc gases, whereas elements preferably forming sulﬁdes, hydrides and free atoms, have higher Kd* in sulfur-rich, HCl-poor and reduced rift/hot-spot gases. Degassing directly from the free melt surface is negligible; deep gas passing through the erupting vent is quickly overwhelmed by the signal of low-pressure degassing. Equilibration of rising bubbles with the surrounding melt almost eliminates the diﬀerence between Kd* calculated for degassing lava ﬂows (no connection with deep magma) and for lava lakes and open-vent volcanoes (convective mass exchange with deep magma takes place). Diﬀusion does not strongly aﬀect the apparent partitioning of magmas degassing at surface. Gas bubbles growing in near-surface silicate melts at atmospheric pressure have a large density diﬀerence compared to the surrounding melt of 12–15 thousand times. This leads to the rapid expansion of such bubbles and a decrease in the thickness of the diﬀusion boundary layer in the melt due to its stretching around the growing bubble, which sharply decreases diﬀusion fractionation. As a result, the apparent partition coeﬃcients (Kd*) for degassing basaltic volcanoes are close to the equilibrium ones (Kd) for most of the elements. The partition coeﬃcients of volatile elements (S and Cl) calculated from the comparison of volcanic gas and rock compositions are in agreement with the values determined previously via experiments or theoretical modeling.
Баранов Б.В., Вернер Р.А., Рашидов В.А., Цуканов Н.В., Дозорова К.А. Морфология подводного вулкана Пийпа в Командорской котловине по данным съемки многолучевым эхолотом // Вестник КРАУНЦ. Серия: Науки о Земле. 2021. Вып. 50. № 2. С. 6-21. doi: 10.31431/1816-5524-2021-2-50-6-21.
We analyzed the bathymetric data obtained during the cruises on the German research vessel “Sonne” using multibeam echosounders within the framework of the Russian-German projects KALMAR (cruise SO201-2, 2009) and BERING (cruise SO249-2, 2016) in the Komandorsky Basin of the Bering Sea. Detailed bathymetric maps of the Piip submarine volcano were constructed. New morphological features of its summit edifices and their age relations are described, hydrothermal activity confined to the edifices is localized, and all side cones and lava flows are mapped. Based on the flank cones and fissure lava flows alignments we determined the tectonic paleostress that existed at the time of their formation, presumably after the Late Miocene-Early Pliocene. It differs from the recent tectonic stress caused by right-lateral displacements along the Bering fault zone.
Белоусова М.Г., Сапрыкина О.Ю., Бубнова Р.С., Шаблинский А.П., Вергасова Л.П., Белоусов А.Б., Филатов С.К. Термическое исследование нового минерала-беломаринаита KNаSO4 // Вулканология и сейсмология. 2021. № 1. С. 57-64. doi: 10.31857/S0203030620060127.
For the first time, the thermal behavior of a new mineral belomarinaite KNaSO4 was studied on a natural
sample and its synthetic analogue in the range of 30‒800°C. The mineral is stable up to a temperature of
475 ± 10°C, at which it has a polymorphic transformation into a high-temperature polymorphic modification
(P63/mmc), stable up to 800°C. The thermal expansion of both modifications is sharply anisotropic, and in
the case of the high-temperature phase it is also variable as a function of temperature ‒ the dependence of the
parameter a has a U-shape with a minimum at T = 660°C. The volumetric expansion of modifications varies
in the intervals of their existence for the low-temperature phase from 80 to 200 (10–6°C–1), for the high-temperature phase, from 350 to 300 (10–6°C–1). That is, on average, the expansion of the high-temperature modification increases by a factor of 2‒3 relative to the expansion of the low-temperature phase, the main increase is in the parameter с and is determined, apparently, by restructuring the structure along this direction.
Бергаль-Кувикас О.В. Изотопно-геохимические характеристики коровых процессов вулкана Ключевской // Вулканизм и связанные с ним процессы. Материалы XXIV ежегодной научной конференции, посвящённой Дню вулканолога, 29-30 марта 2021 г. Петропавловск-Камчатский: ИВиС ДВО РАН. 2021. С. 14-17.
Соотношения редких элементов и изотопные отношения стронция, свинца в лавах вулкана Ключевской указывают на значительные процессы ассимиляции магмы в коре. Расположения побочных прорывов в сравнении с геофизическими наблюдениями позволяют предположить гетерогенность фундамента и наличие регионального разлома, контролирующего проявления побочных извержений.
Бергаль-Кувикас О.В., Биндеман И.Н., Чугаев А.В., Ларионова Ю.О., Перепелов А.Б., Хубаева О.Р. Моногенный вулканизм Малко-Петропавловской зоны поперечных дислокаций: оценка вулканоопасности для территории Авачинского залива, городов Вилючинск и Петропавловск-Камчатский // Вулканизм и связанные с ним процессы. Материалы XXIV ежегодной научной конференции, посвящённой Дню вулканолога, 29-30 марта 2021 г. Петропавловск-Камчатский: ИВиС ДВО РАН. 2021. С. 75-78.
В работе представлены результаты комплексного изучения моногенного вулканизма в МалкоПетропавловской зоне поперечных дислокаций (МПЗ), высказывается предположение о формировании моногенного вулканизма на границах разновозрастных слэбов, на продолжении Авачинского трансформного разлома. В районе МПЗ проживает около 75 % населения (~250 тыс. чел.) Камчатки, поэтому изучение вулканоопасности актуально.