Seismic Tomography of Kamchatkan Volcanoes

—The Kamchatka Peninsula is one of the most tectonically active regions in the world, where intensive and diverse modern volcanic activity takes place. In the recent decade, substantial progress in the investigation of deep structures beneath Kamchatka has been achieved owing to numerous tomography studies based on seismological data provided by permanent stations and temporary networks deployed in some key areas. The goal of this review is summarizing and systematizing dozens of separate multiscale geophysical studies in Kamchatka and constructing an integral model of volcano-feeding systems. An important part of this review contains the description of results of various seismic studies related to the Klyuchevskoy group volcanoes, which can now be considered one of the best studied volcanic areas in the world. The results of the regional-scale seismic tomography reveal the existence of the Pacific slab window, which determines the particular activity of the Klyuchevskoy group volcanoes. Middle-scale tomography studies have found traces of an ascending hot mantle flow that passes through the slab window, reaches the bottom of the crust below Shiveluch Volcano, and then propagates laterally toward the Klyuchevskoy group. Seismic models of the entire crust in the area of the Klyuchevskoy group were used to identify different mechanisms of magmatic feeding of three most active volcanoes: Klyuchevskoy, Bezymianny, and Tolbachik. The data of local networks deployed on several volcanoes of Kamchatka were used to image the magma sources in the upper crust, which are directly responsible for the current eruption activity. The comparison of the results for the Kamchatka volcanoes with tomography models of several other volcanoes of the world allowed determining some common features and differences in feeding active magmatic systems.

Comparative phytochemical analysis of the aerial parts of Empetrum nigrum L. samples, collected in various regions of the Russian Federation

Introduction. A number of studies have shown that various genetic and environmental factors can affect the biosynthesis and accumulation of secondary metabolites. In particular, it is known that the local geoclimate, seasonal changes, external conditions such as light, temperature, moisture and soil fertility can affect the chemical composition and, as a result, the therapeutic properties of plants used in the pharmaceutical and food industries. Empetrum nigrum L. is a rich source of various pharmacologically active secondary metabolites – chalcones, dihydrochalcones, bibenzyls, 9,10-dihydrophenanthrenes, flavonoids, and proanthocyanidins. In the scientific literature, there is no data on the variation in the chemical composition of E. nigrum depending on the growing area. The obtained data are necessary for a reasonable choice of the collecting location for the plant, with the aim of its further chemical and pharmacological research for the development of promising drug candidates.Aim. To carry out a comparative analysis of secondary metabolites composition in the aerial parts of Empetrum nigrum growing in different regions of the Russian Federation.Materials and methods. Samples collected in three different areas were used to compare HPLC profiles: sample 1 was collected next to SPCPU nursery garden of medicinal plants (Leningrad region, Vsevolozhsky district, Priozerskoe highway, 38 km) in July 2020, sample 2 was collected on the Kola Peninsula, around the Khibiny mountains in July 2020, sample 3 was collected on the Kamchatka Peninsula, next to Khalaktyrsky beach (Pacific Ocean coast) in July 2020. Extracts were analyzed by analytical high performance liquid chromatography (HPLC) using a Prominence LC-20 device (Shimadzu, Japan) equipped with a diode array detector.Results and discussion. As a result of the research, for the first time, a significant variation in the qualitative chemical composition in the aerial parts of Empetrum nigrum growing in different regions of Russian Federation was established. Sample 3, collected on the Kamchatka Peninsula, in comparison with samples 1 and 2, contain the greatest variety of polar secondary metabolites belonging to the classes of flavonoids, tannins, and phenol carboxylic acids, while in the shoots collected in the Leningrad region, the major metabolites were weakly polar compounds belonging to the classes of chalcones, dihydrochalcones, bibenzyls, and 9,10-dihydrophenanthrenes, and in sample 2, collected in the Khibiny mountains, the lowest qualitative content of secondary metabolites was found. This variation may be caused by various environmental factors (biotic and abiotic).Conclusion. For the first time, the comparison of HPLC profiles of aerial part samples of E. nigrum, collected in different regions of the Russia Federation has been carried out. As a result, significant variations in the secondary metabolites composition of the studied samples were established, depending on the regions and growing conditions of the plants. The data obtained can be used for a reasonable choice of the collection location for the plant, with the aim of its further chemical and pharmacological research for the development of promising drug candidates.

Walleye pollock (Gadus chalcogrammus, Pallas, 1814) fishery, size and age composition, state of stocks and catch prospects in the waters adjacent to Kamchatka peninsula and Northern Kuril Islands

The article provides data on the catch of the Northern Okhotsk, Eastern Kamchatka and Western Bering Sea walleye pollock stocks, fishery structure by the fishing gears in 2016–2019, size and age composition of the fish in the commercial trawl and Danish seine catches in 2010–2019. Data on the generation abundance and stock condition indices used in the stock assessment models are also demonstrated. Interannual dynamics of the total and spawning stock biomass, determinants of the dynamics and prospects of fishing are analyzed.

Gas Emissions From the Western Aleutians Volcanic Arc

The Aleutian Arc is remote and highly active volcanically. Its 4,000 km extent from mainland Alaska to Russia’s Kamchatka peninsula hosts over 140 volcanic centers of which about 50 have erupted in historic times. We present data of volcanic gas samples and gas emission measurements obtained during an expedition to the western-most segment of the arc in September 2015 in order to extend the sparse knowledge on volatile emissions from this remote but volcanically active region. Some of the volcanoes investigated here have not been sampled for gases before this writing. Our data show that all volcanoes host high-temperature magmatic-hydrothermal systems and have gas discharges typical of volcanoes in oceanic arcs. Based on helium isotopes, the western Aleutian Arc segment has minimal volatile contributions from the overriding crust. Volcanic CO2 fluxes from this arc segment are small, compared to the emissions from volcanoes on the Alaska Peninsula and mainland Alaska. The comparatively low CO2 emissions may be related to the lower sediment flux delivered to the trench in this part of the arc.

Probability assessment of possible ice encounters during the petroleum hydrocarbons transportation in the Sea of Okhotsk

The increase in freight traffic along the Northern Sea Route necessitates the study of the ice regime of the freezing seas of Russia, including the Far Eastern ones (Bering Sea, the Sea of Okhotsk and the Sea of Japan). This paper, on the basis of the analysis of the Sea of Okhotsk’s ice cover and the location of the edges of the Sea of Okhotsk’s ice massif, evaluates the probability of an encounter with ice for the ships in transit during cargo transportation on the Northern Sea Route through the Far Eastern seas along two basic routes from the southern tip of the Kamchatka Peninsula: 1) traverse Cape Lopatka–Sea of Okhotsk–La Perouse Strait; 2) traverse Cape Lopatka–Sangarsky Strait. It was shown that at the stage of ice cover maximum development in the Sea of Okhotsk (February-March), route No. 2 was the most adequate and the safest for ships of ice class Arc4 and below. The section of route No. 1 with a 70 % ice encounter probability was 421 km long in February and 382 km long in March. That section of the route was dominated by very cohesive first-year thin ice up to 70 cm thick with inclusions of first-year ice of average thickness (up to 120 cm).

Dirty thunderstorms caused by volcano explosive eruptions in Kamchatka by the data of electromagnetic radiation

During volcano eruptions, so called dirty thunderstorms are the sources of electromagnetic radiation. They are caused by ash-gas clouds formed during explosive eruptions. Thunderstorm activity in an ash-gas cloud during volcano eruption is monitored by radio equipment. The VLF direction finder, located at Paratunka, monitors thunderstorm activity in the region of Kamchatka Peninsula including dirty thunderstorms accompanying explosive eruptions of Shiveluch and Bezymyanniy volcanoes. In the paper, we analyze records of electromagnetic radiation associated with dirty thunderstorms occurring during volcano eruptions from 2017 to 2020. During that period 24 eruptions of Shiveluch volcano and 5 eruptions of Bezymyanniy volcano occurred. Seventeen and three of them, respectively, caused dirty thunderstorms. Two-stage scenario of development is typical for all the dirty thunderstorms. The first stage lasts for 5–7 minutes and accompanies eruptive column development. However, if the eruption begins according to a smooth scenario, the first stage may be weak. The second stage lasts for 20–80 minutes and is associated with eruptive cloud formation and propagation. The intensity of this dirty thunderstorm stage depends on eruption power as well as on the interaction of an eruptive cloud during its propagation with the clouds of meteorological origin. Based on the obtained data, that is indicated by the increase of cloud-to-cloud stroke number.

Reaction in the field of subsoil gases to the preparation of the earthquake on March 16, 2021 with MW = 6.6 (Kamchatka, Russia)

The paper presents the data of monitoring of subsoil gases on Kamchatka peninsula. Before the earthquake with Mw=6.6 on March 16, 2021 near Kamchatka, anomalous variations were revealed in the field of subsoil gases, which are probably associated with the passage in the earth’s crust of solitary deformation pulses, called deformation waves. Such deformation pulses can affect the permeability of rocks and cause changes in the radon flux to the surface at the locations of the sensors. Based on the complex of emanation data, the earthquake of March 16, 2021 with Mw=6.6 was successfully predicted.

Estimation of Probability Distributions of Geoacoustic Signal Characteristics

The paper presents an estimation of probability distributions of geoacoustic signal characteristics. The studied signals have a pulsed nature. The ones have been recording at the geodynamic test site of the IKIR FEB RAS (Kamchatka Peninsula) for more than 20 years. To estimate the distribution of characteristics, such time intervals were determined in which histograms of the distribution did not change. The following characteristics were chosen for the estimation: maximum amplitude, the position of pulse envelope maximum, duration, filling frequency, and pulse-to-pulse interval. The obtained estimates made it possible to develop an empirical model of the geoacoustic emission signal. The model can help to test new and existing algorithms for the processing and analysis of geoacoustic signals. The paper also shows that the formalization of the selected characteristics makes it possible to search for anomalies, including those associated with seismic events, by the characteristic variations.

Diatoms in Volcanic Soils of Mutnovsky and Gorely Volcanoes (Kamchatka Peninsula, Russia)

Volcanic activity has a great impact on terrestrial ecosystems, including soil algae in general and diatoms in particular. To understand the influence of volcanoes on the biodiversity of diatoms, it is necessary to explore the flora of these microorganisms in regions with high volcanic activity, which includes the Kamchatka peninsula. During the study on diatoms in the soils of Mutnovsky and Gorely volcanoes of Kamchatka, 38 taxa were found. The Mutnovsky volcano diatom flora was more diverse and accounted for 35 taxa. Eunotia curtagrunowii, Humidophila contenta, and Pinnularia borealis were the dominant species. In the Gorely volcano, only 9 species were identified, with Caloneis bacillum and Pinnularia borealis prevailing in the samples. Overall, the genera Pinnularia and Eunotia were the most diverse in the studied area. The diatom flora of the studied volcanoes comprises mostly cosmopolitan small-sized taxa with a wide range of ecological plasticity. Our data confirm the high adaptive potential of diatom algae and add new knowledge about the ecology and biogeography of this group of microorganisms.