Constructive and Destructive Processes During the 2018–2019 Eruption Episode at Shiveluch Volcano, Kamchatka, Studied From Satellite and Aerial Data

Dome-building volcanoes often develop by intrusion and extrusion, recurrent destabilization and sector collapses, and renewed volcanic growth inside the collapse embayment. However, details of the structural architecture affiliated with renewed volcanic activity and the influences of regional structures remain poorly understood. Here, we analyze the recent activity of Shiveluch volcano, Kamchatka Peninsula, characterized by repeated episodes of lava dome growth and destruction due to large explosions and gravity-driven collapses. We collect and process a multisensor dataset comprising high-resolution optical (aerial and tri-stereo Pleiades satellite), radar (TerraSAR-X and TanDEM-X satellites), and thermal (aerial and MODIS, Sentinel-2, and Landsat 8 satellites) data. We investigate the evolution of the 2018–2019 eruption episode and evaluate the morphological and structural changes that led to the August 29, 2019 explosive eruption and partial dome collapse. Our results show that a new massive lava lobe gradually extruded onto the SW flank of the dome, concurrent with magmatic intrusion into the eastern dome sector, adding 0.15 km3 to the lava dome complex. As the amphitheater infilled, new eruption craters emerged along a SW-NE alignment close to the amphitheater rim. Then, the large August 29, 2019 explosive eruption occurred, followed by partial dome collapse, which was initially directed away from this SW-NE trend. The eruption and collapse removed 0.11 km3 of the dome edifice and led to the formation of a new central SW-NE-elongated crater with dimensions of 430 m × 490 m, a collapse scar at the eastern part of the dome, and pyroclastic density currents that traveled ∼12 km downslope. This work sheds light on the structural architecture dominated by a SW-NE lineament and the complex interplay of volcano constructive and destructive processes. We develop a conceptual model emphasizing the relevance of structural trends, namely, 1) a SW-NE-oriented (possibly regional) structure and 2) the infilled amphitheater and its decollement surface, both of which are vital for understanding the directions of growth and collapse and for assessing the potential hazards at both Shiveluch and dome-building volcanoes elsewhere.

Materials to cyanobacterial and algal flora from volcanic soils of Shiveluch volcano

During the species composition study of terrestrial cyanobacteria and algae from volcanic soils of Shiveluch Volcano (Kamchatka peninsula, Russia) eighteen taxa from five phyla were revealed: Cyanobacteria – 4, Bacillariophyta – 4, Ochrophyta – 2 (Eustigmatophyceae – 1, Xanthophyceae – 1), Charophyta – 1, Chlorophyta – 7 (Chlorophyceae – 2, Trebouxiophyceae – 5). Nitzschia communis Rabenhorst, Nitzschia palea (Kützing) W. Smith, Eolimna minima (Grunow) Lange-Bertalot, Eremochloris sp., Tetradesmus obliquus (Turpin) M.J. Wynne, Nostoc edaphicum Kondratyeva were most frequency.

SQUEEZING OUT PLASTIC LAVA BLOCKS ON YOUNG SHIVELUCH VOLCANO (KAMCHATKA) IN 2020–2021

Volcano Young Sheveluch is one of the most active volcanoes in Kamchatka. Since August 1980 to the present time, an extrusive dome has been growing in the crater of the volcano. Plastic lavas in the form of large ribbons were noted on the dome already in 1980–1981, the first lava flow was observed after a paroxysmal eruption on May 9, 2004. The next large block of lava started to extrude in the end of April – beginning of May 2020. By June, 11th, it rose above the dome on 50–80 m, and up to 120 m by the end of October. On September 28, it was noted that the lava block acquired smooth surfaces. Portions of lava squeezed out from inside of the volcano in August – September were plastic. By December 8, the block had collapsed. In February 2021, a new block of plastic lava began to rise from the destroyed block. In March its height above the dome exceeded 50–60 m, and 200 m in June.

VOLCANOES OF KAMCHATKA

The results of near real-time monitoring of the active Kamchatka volcanoes are described. Continuous monitoring was carried out using three remote methods: 1) seismic monitoring according to automatic telemetric seismic stations; 2) visual and video observation; 3) satellite observation of the thermal anomalies and the ash clouds. Daily information about volcanic activity is published in the Internet (http://www.emsd.ru/~ssl/ monitoring/main.htm) since February 2000. Annual results of seismic activity of the Northern (Shiveluch, Klu-chevskoy, Bezymianny, Krestovsky and Ushkovsky), Avacha (Avachinsky and Koryaksky), Mutnovsky-Gorely volcano group and Kizimen volcano are presented. 4983 earthquakes with КS=2.1–8.7 were located for Northern volcano group, 469 earthquakes with КS=1.6–6.1 – for Avacha volcano group, 459 earthquakes with КS=1.9–6.1 – Mutnovsky-Gorely volcano group, 220 earthquakes with КS=2.4–8.5 for Kizimen volcano and 238 earthquakes with КS=2.5–8.4 for Zhupanovsky volcano in 2014. Maps of epicenters, quantities of seismic energy and earth-quake distribution according to class are given. All periods of activity were fixed and investigated by remote me-thods in 2014: intensive volcanic activity of Shiveluch volcano associated with new cone, a con-tinuation of the seismic and volcanic activity of Zhupanovsky volcano after 56-year quite period and the ending of the summit explosive-effusive eruption of Kluchevskoy volcano in January-February.

Classification of volcanic and tectonic earthquakes in Kamchatka (Russia) with different machine learning techniques

<p>Kamchatka is an active subduction zone that exhibits intense seismic and volcanic activities. As a consequence, tectonic and volcanic earthquakes are often nearly simultaneously recorded at the same station. In this work, we consider seismograms recorded between December 2018 and April 2019. During this time period when the M=7.3 earthquake followed by an aftershock sequence occurred nearly simultaneously with a strong eruption of Shiveluch volcano. As a result, stations of the Kamchatka seismic monitoring network recorded up to several hundreds of earthquakes per day. In total, we detected almost 7000 events of different origin using a simple automatic detection algorithm based on signal envelope amplitudes. Then, for each detection different features have been extracted. We started from simple signal parameters (amplitude, duration, peak frequency, etc.), unsmoothed and smoothed spectra and finally used a multi-dimensional signal decomposition (scattering coefficients). For events classification both unsupervised (K-means, agglomerative clustering) and supervised (Support Vector Classification, Random Forest) classic machine learning techniques were performed on all types of extracted features. Obtained results are quite stable and do not vary significantly depending on features and method choice. As a result, the machine learning approaches allow us to clearly separate tectonic subduction-zone earthquakes and those associated with the Shiveluch volcano eruptions based on data of a single station.</p>

A model to calculate electrostatic charge structure of eruptive clouds from volcanic eruptions

The paper proposes a model to calculate electrostatic charge structure of an eruptive cloud (EC) based on the response of atmospheric electric field (AEF EZ) strength during cloud passage near an observation site. The model provides high identity of calculated and experimental data for complex configurations of EC electrostatic charges. Examples of calculation of EC structures from Shiveluch volcano (Kamchatka) eruptions are given. They were estimated with the help of the developed model based on the records of AEF EZ response at the distances of 45 and 113 km.

The main trends in the dynamics of vegetation on the territory affected by the catastrophic eruption of Bezymyanny Volcano on March 30, 1956 (Kamchatka)

The transformation of the vegetation cover in the impact zone of the 1956 eruption, in territories covered by various deposits, is considered. As a result of a gigantic eruption (VEI 5), vegetation was exposed to a series of different volcanic impacts. Five main categories of events are distinguished: the movement of material of a huge volume of volcano edifice over a large distance as a result of a giant clastic avalanch, the pyroclastic surge of a direct blast, the pyroclastic flows, the formation of a giant eruptive cloud and ashfalls, as well as the lahars. The volume of erupted (initially high-temperature) deposits was, according to various estimates, in the amount of 1.35-1.5 km3, the volume of cold deposits of a clastic avalanche was 0.5-0.8 km3. The volume of lahar was 0.5 km3. The area covered by the pyroclastic wave of the directed explosion was about 500 km2. Within this lesion zone, deposits of pyroclastic flows have occupied 30-40 km2, and clastic avalanche deposits from 35 to 60 km2. Below 900 m above sea level (a.s.l.) these deposits buried cover of subalpine dwarf alder (dominant species is Alnus fruticosa) and mountain meadow vegetation, as well as forest vegetation (dominant species is Betula ermanii) at its upper limit. Forest and partially dwarf alder vegetation was destroyed on a vast territory mainly under the influence of a pyroclastic wave (in the altitude range from 700-800 to 200 m a.s.l.), as well as lahars (in the range of 250-50 m a.s.l.). Primary successions occur in the alpine and partially subalpine zone on avalanche deposits and pyroclastic flows deposits, as well as in the upper part of the zone impacted by pyroclastic surge of the direct blast (40-45 km2). In part of the territories where thick deposits of the lahars were formed, primary successions also probably occurred. In the zone of primary successions, deposits of a clastic avalanche are settled by plants most slowly due to not-favourable edaphic factors. The process is somewhat more efficient on the deposits of pyroclastic flows (the same ratio was noted on the Shiveluch Volcano). The surface overlapped by deposits of the pyroclastic surge is populated relatively quickly. Secondary succession occurs in the zone of damage to the forest and dwarf trees by the influence of a pyroclastic wave, as well as in the zone of passage of the lahars. Restoring of vegetation to its previous state will take from 50 to ~500 years on different deposits and in different parts of an impact zone.