The ERA5 reanalysis data (ocean surface temperature, surface atmospheric pressure and wind speed and direction) for 1998‒2023 in the northwestern part of the Pacific Ocean and the Far Eastern seas were analyzed. The main objective of the study was to determine the statistical characteristics of SST anomalies and the nature of the spatial distribution of the most significant ones. The distributions of surface atmospheric pressure and wind speed during their formation were also considered to assess the possible role of meteorological conditions in deviations of thermal conditions from the norm. We found that significant events (deviations of the actual average monthly values, which exceeded twice the value of the standard deviation by at least 5 % of the studied water area) are not rare. Negative anomalies accounted for about 9 %, and positive anomalies accounted for 14 % of all situations considered. These anomalies are unevenly distributed over time: negative anomalies predominated in the initial period, while positive anomalies prevailed in the final period. A period of relative thermal stability was observed from 2003 to 2019. Meteorological conditions during the formation of SST anomalies also differed from normal; however, the mechanism underlying their influence remains unclear. Anomalies in latent and sensible heat fluxes were, in most cases, relatively small.
Two major seismic activations were observed on the northeastern coast of Honshu Island in November– December 2025. The first activation was localized in the area of the Japan Trench, and the second was located in the same area but closer to the border between the Japan and Kuril-Kamchatka Trenches. The largest event during this time was the Aomori earthquake on December 8, 2025 with M = 7.6. The seismic process in the subduction zone is primarily a consequence of the movement of tectonic plates, which causes excessive stress load at the sites of their collision. Therefore, these activations may be related to the deformation processes in the area of the Southern Kuril Islands, which are located about 400 km away. This paper presents the results of rock deformation measurements from August to December 2025 on Shikotan Island (the Lesser Kuril Ridge). Measurements were conducted using strainmeters installed in the underground pavilion (adit) of the Shikotan seismic station of the Sakhalin Branch of the GS RAS. Analysis of the data collected over five months of measurements revealed two characteristic periods in the deformation process. The first one began after a strong aftershock (September 18, 2025, M = 7.8) in the area of the Kamchatka earthquake on July 29(30), 2025, M = 8.8, and is associated with a change of sign and a high rate of deformation. The second period began in November 2025 and was associated with zero deformation rates. This period coincided with two powerful seismic activations in the Japan Trench area east of Honshu Island, with a characteristic northward migration toward the Hidaka collision zone. Previously obtained results on the influence of strong atmospheric cyclones (in the form of pulse variations) on rock deformation in the adit were also confirmed.
In recent years, an increase in the occurrence and dispersal of broomrape species (Orobanchaceae Vent.) into new habitats has been observed in a number of regions of the Russian Federation. Nine broomrape species are known in the Saratov Region, including the sunflower broomrape (O. cumana), which damages sunflower crops. However, the presence of the branched broomrape (O. ramosa) and the pale broomrape (O. reticulata subsp. pallidiflora) in the region requires confirmation. This paper presents the results of modeling potential bioclimatic ranges using the MaxEnt algorithm for four broomrape species (Orobanche сumana Wallr., O. reticulata subsp. pallidiflora (Wimm. Grab.) Hayek., O. ramosa L., and O. caesia Rchb.). The range of some climatic variables at the registration points of the species under consideration within the distribution range in Europe and Central Asia and their ecological-climatic optimum are determined and compared with the climatic parameters of the Saratov Region. Bioclimatic modeling revealed the absence of areas in the Saratov Region with suitable climatic parameters for the growth of O. reticulata subsp. pallidiflora and O. ramosa. However, single cases of these species in agrocenoses have been described. High bioclimatic suitability of the areas was identified, and, consequently, the likelihood of further dispersal of O. cumana is high both in the Saratov Region and in some neighboring regions (Orenburg Region, Republic of Bashkortostan). O. caesia is also located in the ecological-climatic optimum zone in the Saratov Region.
The information on the dynamic parameters (DP) of 261 earthquakes with KP = 5.2–13.1 (KP, earthquake class according to Pustovitenko and Kulchitsky) that occurred from 1990 to 2022 was collected for the Crimean-Black Sea region from various sources. These parameters include scalar seismic moment of M0, source radius r, stress drop delta sigma, etc. The distributions of the DP depending on the magnitude and scalar seismic moment were constructed and approximated by a linear function; in some cases, a power function was additionally considered. The determination coefficient R2 was calculated. The dependence of the logarithm of the scalar seismic moment for the Crimean-Black Sea region is lg(M0) = 0.87M + 11.4 (R2 = 0.84). The areal distribution of the average annual rate of seismotectonic deformations (STD intensity) was constructed based on the earthquake catalog (1993–2022). The STD intensity was compared with the stress drop level. Based on the data on the stress drop for the Crimean-Black Sea region, the areal distribution of the weighted average of the stress drop was constructed.
The development of vegetation on the eastern coast of Primorye in the low and middle mountains of the eastern macro-slope of Sikhote-Alin over the past 5500 years was reconstructed based on the pollen analysis of lacustrine and bog sediments. The temporal resolution of the reconstructions is 30–88 years. Twenty phases of vegetation development, lasting from 670 to 120 years, were identified, amidst which the multidecadal variations took place. The transport of pollen and spores played a certain role in the variability of pollen spectra. Short-term hydroclimatic changes are reflected in the structure of the pollen spectra as changes in the ratio of broadleaf to dark coniferous pollen, the peaks of which are consistent with solar activity variations. A long phase of stable development of Korean pine-broadleaf forests was noted at the end of the Middle Holocene (5050–4380 yr BP). Vegetation changes were recorded during the 4.2 ka event, characterized by cool climatic conditions and low humidity. Korean pine generally expanded in cooler and more humid conditions, and its presence declined during the periods of low humidity. The biggest distribution of Korean pine forests was recorded during 2820–2640 yr BP cooling. Dark coniferous forests became widespread at the beginning of the Little Ice Age. The role of birch trees increased in the late Holocene and modern conditions. Alder thickets spread along the swampy shores of the lake during decreased humidity. Slopewash, which intensified during the periods of high typhoon frequency, played a significant role in spore transport. Allochthonous pollen (Cryptomeria, Fagus) transported in bioaerosols from remote areas, possibly from the Japanese Islands, was found. Ephedra pollen might have been carried by dust storms from the continental interiors. Signals of anthropogenic influence on the landscape have been noted since the Bronze Age. The most significant human impact to forests occurred in the late 19th and early 20th centuries, before the establishment of a nature reserve.
A comprehensive study of Kaliningrad soils was conducted to assess the level and structure of chemical pollution. The study demonstrates the fundamental importance of using a local background, rather than global clarkes, for reliable assessment of anthropogenic impact. The stable polycomponent pollution of soils in Kaliningrad was identified, with the formation of clearly localized geochemical anomalies. The methods of statistical analysis and geographic information mapping revealed two main sources of pollution, spatially coinciding with the zones of intensive industrial and port activity. The most significant accumulation was found for lead and zinc, the levels of which reached the levels of "severe" pollution. The application of the index system (Igeo, PI, EF, NPI, PLI, Zc) made it possible to differentiate the territory by the degree of soil pollution and identify the nature of the sources of pollutants. The results obtained prove the need for geoecological monitoring and the development of targeted environmental protection measures for identified areas of environmental pollution.
This study presents, for the first time, a comprehensive typological classification and mapping of the littoral landscapes in the eastern part of Salmon Bay (Aniva Bay, the Sea of Okhotsk, southern coast of Sakhalin Island), using methods of underwater landscape (bentema) typology developed for the Sea of Japan (according B.V. Preobrazhensky et al.). The research utilized data collected in the intertidal zone, which provided a representative sampling of relief forms, substrate types and skeletal content, as well as the state of the macrobenthos. Seven main types of bentema are described: metagest, skatebra, fractum, segetium, arenoid, peltium, and saxosium. For each landscape type, key morphological, granulometric, and biotic parameters are provided, as well as the main edificators and characteristic species. The study found that traces of organism activity (vestigial features) contribute to a more accurate determination of landscape boundaries. The results demonstrate the possibility of adapting the sublittoral bentema typology to the littoral zone and confirm its effectiveness for the recognition and structurally mapping of the dynamic coastal ecosystems. The classification system, which integrates physicogeographical and biotic parameters, can be used to monitor the state of coastal ecosystems and conduct comparative studies in coastal waters, as well as to objectively map the landscapes of the littoral.
The study is devoted to solving the problem of determining regional relationships between the characteristics of the underwater light field and the bio-optical characteristics of the seawater column. The aim of the study is to determine the influence of chlorophyll-a (Chl-a) (C) and colored dissolved organic matter (CDOM) (D) concentrations on the variability of underwater photosynthetically active radiation (PAR) for certain areas of Peter the Great Bay in the Sea of Japan (Amur Bay, Ussuri Bay, and Posyet Bay). To this end, the dependence of the diffuse attenuation coefficient (KPAR) of the underwater PAR on each of the specified bio-optical characteristics in these areas was analyzed. The experimental data were obtained by measuring chlorophyll-a and CDOM concentrations using the SeaBird SBE 19-plus multiparameter probe with the Licor Li-193 spherical PAR sensor and calibrated WETStar fluorescent sensors. Three types of models were used in the study: KPAR was calculated only through C (mC), only through D (mD), and simultaneously through C and D (mCD). It was found that in Amur Bay and Ussuri Bay, KPAR variability is primarily influenced by variations in CDOM content, while in Posyet Bay, it is determined by variations in Chl-a concentration. Incorporating both Chl-a concentration and CDOM concentration (mCD model) in all analyzed cases increases the accuracy of KPAR estimation from measurements of optically active components by 30–40 %. For the general model, this approach improves accuracy by approximately twofold compared to using Chl-a concentration alone. The application of the general mCD model for different areas of Peter the Great Bay yielded KPAR estimates with the following relative root mean square errors: 𝑅𝑀𝑆𝐸 %Amur mCD =23.6, 𝑅𝑀𝑆𝐸 %Ussur mCD =19.3, 𝑅𝑀𝑆𝐸 %Posyet mCD =15.5. It is advisable to use the general mCD model, as it demonstrates greater adaptability to regional conditions in Peter the Great Bay.
The article involves the study of the freezing process of medium-grained sand saturated with aqueous NaCl solutions of various concentrations (0–104 g/l). The purpose of the study is to determine the influence of NaCl concentration on heat and mass transfer processes. Freezing was initiated from one end of the sample; the temperature field was recorded by eight thermocouples, while the moisture distribution was determined by weighing followed by drying. The results confirmed a linear decrease in the freezing point of pore water with increasing NaCl concentration, down to –7°C. It was found that in all tests, moisture redistribution occurred with its accumulation near the freezing front. In non-saline samples this effect was most pronounced, which can be attributed to the combined influence of thermodiffusion and phase pressure differences at the water–ice interface. With increasing salinity, this effect weakened, and the contrast in moisture content between frozen and unfrozen zones decreased. The obtained time-space distributions of temperature and moisture provide a basis for parameterizing mathematical models of heat and mass transfer in frozen media, as well as serve as a starting point for further studies of freezing processes in saline soils.
We present the results of a comprehensive study of high PCO2 mineral waters of Primorsky Krai, aimed at identifying their genesis and conditions of formation. For the first time, a joint analysis of the chemical and micro component composition of water, the gas phase (CO2, N2, CH4, H2, He, and Ar), and stable isotopes of oxygen and hydrogen (δ18O, δ2H) was carried out for a number of poorly studied springs, gained either during this study or previously by our group. Three genetic groups of waters were identified based on hydrogeochemical data: 1) Ca-HCO3 type waters (Bolshoy Klyuch and Fabrichny springs) formed in terrigenous strata; 2) deep silicate-type waters (Pokrovsky and Glukhovka springs) associated with interaction with crystalline basement rocks and enriched with lithium, rubidium, and barium; 3) acidic waters of the sulfide oxidation zone (Nerobinsky spring), which are indicators of ore mineralization; 4) mixed-type waters showing the features of the three types described above. Gas-geochemical studies confirmed the predominance of CO2 of mantle genesis ( >96.9 vol.%) and the redox environment. Unique anomalies were identified, such as a high methane content (up to 2.26 vol.%) in the Pokrovsky spring, indicating possible thermogenic processes. The isotopic composition of the waters (δ18O from –14.71 to –8.70 ‰, δ2H from –103.79 to –60.28 ‰) clearly indicates their meteoric origin from cold climate precipitation, while the shift relative to the global meteor line indicates intensive isotope exchange in the water rock–gas system. The results of the study are of fundamental importance for understanding the fluid dynamics of the Sikhote-Alin subsurface and can be applied for expanding the mineral resource base, developing balneology, and conducting geological prospecting in the Primorsky region.
The article presents the results of studies on establishing the location of the upper (river) boundary of the river mouth areas using the hydrological and morphological approach. Its location for two dozen rivers was determined based on the results of satellite imagery interpretation. Free-access satellite materials (Yandex-maps, GoogleMaps) were used. The selection of rivers for the study was the presence of direct and indirect signs of the spread of marine processes (tides and wind surges) in river channels and floodplain geosystems. River sections differing in the morphodynamic type of the channel and the morphometry of its elements were identified. The location of the river boundary of the river mouth area and the distance to it from the river mouth section were determined by the change (decrease) in the gradient of the frequency of change of these sections. For small rivers, the medium length of the mouth area was 22.6 km; for “small-medium” rivers, 54.4 km; for medium rivers, 42.3 km. The share of the length of the river mouth area in the length of small rivers is about 30 % on average; “small-medium” rivers, 21 %; medium rivers, 9 %.
Preliminary results of field surveys (July 2025) of the ultra-acid sulfate-chloride thermal springs of the " Blue Lakes" which discharge in the Kipyashchiy Stream valley on the slope of the active Baransky volcano (Iturup Island, Southern Kuril Islands), are presented.
This article presents data on the neotectonics and seismicity of the Crimean Peninsula. Using two versions of the structural-geomorphological method – a manual version and a version with the SimSGM software – the neotectonic stress state of Steppe Crimea and adjacent territories was characterized in relation to the peninsula's current seismicity. Areas of fracture concentration of the tension and shear types were identified. The results show that the stress field is characterized by a strike-slip pattern, with a predominantly northeast-oriented compression axis and the least pronounced northwest-trending compression. The relief and its main features are expressed as heterogeneities with an orthogonal strike for Steppe Crimea and a diagonal strike for Mountainous Crimea. The obtained data on the distribution of shear and tension megafractures and seismicity are essential for understanding the formation of hazardous geological processes and are also useful in the design of civil structures and the exploration of ore and oil deposits, as blocks with tension fractures are more fluid-permeable and subject to more intense failure. The low seismic activity is likely due to, firstly, the small number of seismic stations and, secondly, the release of accumulated crustal stresses in the Black Sea basin.
On October 4(5), 1994, one of the strongest tsunamigenic earthquakes in the history of the Southern Kuril Islands occurred, which was accompanied by large-scale tectonic manifestations. Intense shaking led to the collapse of the entire infrastructure on Shikotan and Kunashir Islands; 11 people died. The tsunami that followed the earthquake reached a height of about 10 m on the ocean side of Shikotan Island and was recorded along the entire coast of the Pacific Ocean. Generally, the study of the manifestations of this event had been carried out since October 1994 and ended in 1997 with the publication of extensive reviews. For the first time, the data on the specific effects on the ocean surface (seaquake) that accompanied this earthquake have been collected and systematized. In the following years, the interest in this extraordinary event initiated further research. At the same time, the study of the deposits of the tsunami of October 4(5), 1994, in the general context of study of ancient tsunami (paleotsunami) deposits in this region came to the fore. These studies allowed us to obtain estimates of the "preservation"/ "erasure" of the traces of this tsunami and more ancient events on the coast of the Southern Kuril Islands. Some important data presented in this review are being published for the first time.
It is generally believed that the sulfur of volcanic lakes is of exogenous origin and is formed as a result of the interaction of volcanic gases with each other and with atmospheric oxygen in the aquatic environment. This work contains descriptions the deposits of water-deposited sulfur, at clarifying the conditions and causes of their formation, and at assessing the importance of these deposits in the general genesis of sulfur in volcanic lakes. The conducted field, laboratory, and theoretical studies, taking into account the previously obtained results, do not confirm the exogenous origin of sulfur in volcanic lakes. Sulfur from hydrothermal springs on the surface and at the bottom of volcanic lakes, seas, and oceans is exclusively of endogenous (condensate) origin. Colloidal sulfur also has an endogenous (condensate) origin and does not precipitate in turbulent and convective water flows, gradually collapsing in sulfur disproportionation reactions. Aqueous deposits of fine crystalline sulfur occur under specific conditions of a saturated concentration of sulfur suspension. These deposits are the same local phenomenon as the formation of needle-shaped crystalline sulfur around gas outlets in terrestrial thermal fields.
This study proposes an automatic classification approach for seismic events, designed to discriminate between earthquakes and anthropogenic explosions by employing the Random Forest algorithm. The model operates exclusively on features extracted from the signal recorded at a single seismic station without considering the source location or depth. The feature vector included amplitude ratios, along with temporal, spectral, and fractal parameters of the seismogram. A balanced dataset comprising more than 24 000 seismic records from the Pacific Northwest Curated Seismic Dataset was utilized for training and validation. The trained classifier achieved an accuracy of about 94 % on the test dataset. Feature importance analysis indicated that temporal, fractal, and spectral parameters contributed most to the classification, which is consistent with the underlying differences in the generation of natural and anthropogenic signals. The obtained results demonstrate that the proposed method ensures reliable and robust classification performance and can be applied for automatic filtering of anthropogenic events in seismic monitoring.
Extensive empirical data have been accumulated during long-term monitoring on Kamchatka, which reflect the dynamics of the parameters of the acoustic emission (AE) of near-surface sedimentary rocks during the initiation of strong earthquakes. The article is devoted to the study of the characteristics of the acoustic signal in the frequency range of 10 Hz to 10 kHz, the source of which is near-surface sedimentary rocks. A hypothesis was formulated suggesting that fragments of the AE signal lasting from several hours to several days contain features indicating the initiation of seismic events preceding strong earthquakes in Kamchatka. To verify this hypothesis, a study was carried out to identify a specific class of anomalies in the parameters of AE signals correlated with the occurrence of strong seismic events. The key challenge in this task was determining the temporal boundaries of the intervals during which these anomalies occur. A significant diversity in the forms of anomalies and their temporal duration was discovered, caused by the nonlinearity of AE generation processes and the influence of a wide spectrum of external natural factors. Under such conditions, the successful identification of the desired features of the parametric relationship between the observed AE anomalies and subsequent earthquakes depends strongly on the proper selection of boundaries of the signal processing intervals. The study presents the solution to the problem of determining interval boundaries, provides evidence for the existence of a class of anomalies associated with the initiation of earthquakes, and introduces a method for finding the optimal time interval for identifying such anomalies using artificial intelligence.
This paper presents a description of the fieldwork conducted in Krasheninnikov Bay on Paramushir Island in July–August 2025 by researchers from the Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences. The fieldwork was carried out during the Russian Geographical Society’s expedition “Eastern Bastion – Kuril Ridge.” To study volcanic and hydrothermal activity in the area, rock samples were collected from formations composing the unified Pleistocene basement of the Chikurachki, Tatarinov, and Lomonosov volcanoes, as well as samples of lava from these volcanoes. At the summit of Tatarinov volcano, aerial and surface temperature surveys of the crater were performed using an unmanned aerial vehicle equipped with a thermal imaging camera. Mineralogical sampling of fumarolic fields on the volcano was also carried out. To determine the geochemical characteristics of geobiocenoses near active volcanoes, soil sampling and hydrochemical testing of major watercourses in Krasheninnikov Bay were conducted. The collected field material (samples of rocks, waters, and products of fumarolic activity) provides the basis for further mineralogical and geochemical studies.
This paper presents the results of studies of the spawning conditions of Japanese anchovy Engraulis japonicus in the southeastern part of Sakhalin Gulf at the end of August 2011. The development of eggs and larvae occurred over a wide range of temperature and salinity. Nevertheless, during spawning, anchovy avoided the areas of the intrusion of cold waters of the Sea of Okhotsk, strongly desalinated Amur waters and the areas of coastal runoff with turbidity greater than 7 FTU and salinity less than 10 ‰. Mass spawning occurred within a limited depth range of 13–15 m with an average temperature of 9.9 °С throughout the whole layer and 15.3 °С at the surface, salinity of 22.1 and 19.3 ‰ and water turbidity of 1.9 and 2.3 FTU, respectively. High abundance of eggs – up to 657 eggs/m3 in the water column and up to 223 eggs/m3 in the surface layer – were formed in local areas with high productivity of planktonic and benthic communities. The area of maximum concentration of eggs coincided with the deepening of waters with temperatures of 8–10 ºC and higher up to the 10 m layer. In this layer, stable oxygen content of 8–10 mg/l and low turbidity of up to 2 FTU were observed. The proportion of non-viable eggs was low, from 0.7 % in the surface layer to 4.4 % in the water column. The total duration of spawning in Sakhalin Gulf was assumed to be 1.5 months.
The paper describes the initiation, devel opment, and results of the first volcanological studies under the leadership of Vsevolod Nikolaevich Shilov conducted by SakhKNII AS USSR (Sakhalin Integrated Research Institute of the Academy of Sciences of the USSR) from 1958 to 1971, as well as the history of the establishment of the Laboratory of volcanology.
