The tectonic zoning of the African-Antarctic sector of the Southern Ocean was carried out on the basis of cluster analysis of a large volume of heterogeneous geophysical and geological data. It is known that the degree of geological and geophysical exploration of this part of the ocean by marine surveys and drilling remains extremely low. The results of such an analysis make it possible in areas with weak geophysical knowledge to quickly draw up tectonic zoning schemes based on regional geophysical data that are freely available throughout the entire territory of the world ocean and use them as a basis for further interpretation. The following materials were used as input data or classification features: ocean floor topography, gravity anomalies in free air and in the Bouger reduction, ∆Ta anomalous magnetic field model, ocean floor age, geoid height data, and the SL2013sv seismotomography model. «K-means» algorithms and the «Gaussian mixtures» method used for clustering. Based on the results of the application of these algorithms, cluster models of the study region were obtained, in which the selected classes fully reflect the main tectonic elements.

An algorithm for solving the inverse problem of electrical prospecting by the method of vertical electrical sounding (VES) using neural networks (NN) is presented. The use of NN is aimed at identifying complex patterns and dependencies that may not be available for traditional methods of quantitative interpretation of electrical prospecting data. The algorithm includes the formation of a training sample; training NN and directly obtaining solutions; combination of solutions found with the help of NN and selection of the optimal solution to the inverse problem of VES. The algorithm is tested on model data and practical materials in order to evaluate its capabilities. Geoelectric sections constructed using NN based on the results of field observations were compared with the results of quantitative interpretation performed in the «ZOND» program. The advantages and disadvantages of the created algorithm for solving the inverse problem of VES, as well as ways for its further development are characterized.

For monitoring hard-to-reach thermal facilities, remote surveillance techniques from unmanned aerial vehicles (UAVs) equipped with a thermal infrared camera represent a progressive platform for rapid information collection. This paper presents the first results of such an application of UAVs to study five thermal objects on the Kuril Islands. Four of them (Kipyashchaya Riwer on Iturup Island, Lake Biryuzovoye on Simushir Island, Yankich Island and Yurieva River on Paramushir Island) are associated with active volcanoes. Heat maps with precise geographical reference have been obtained for all sections of gas hydrothermal discharge. For Kipyashchaya River and Yankich Island verification of air thermometry by ground data was performed and real atmospheric attenuation coefficients were obtained for different flight altitudes under observed meteorological conditions. The first data on the parameters of the thermal plume from the hot Yurievа River flowing into the Sea of Okhotsk were obtained.

The work is devoted to the practical aspect of separation of pulse-type signals of lithospheric origin in the recorded electromagnetic field by their shape. Experiments on registration of electromagnetic field signals in a wide frequency range have been carried out. In the frequency range from 5 to 20 kHz, pulses consistent with the generalized shape of the pulse of lithospheric origin were detected. Special hardware and software was developed for registration and further processing of electromagnetic field signals in the kilohertz range. With its help, prototypes of pulses of lithospheric origin were identified. An algorithm was proposed and tested, which makes it possible to automatically select pulses similar to the prototype from the entire set of observed data. Field experiments were carried out to isolate pulses of electromagnetic field of lithospheric origin and to determine their energy and quantitative characteristics. Daily variations of the average energy and activity of electromagnetic field pulses of lithospheric origin are revealed.

New and previously published isotope-geochemical material on the Upper Cretaceous-Lower Paleogene volcanic complexes of the Ozernovsky-Valaginsky segment of the Achaivayam-Valaginsky paleoarc are presented. It is found that composition of rocks composing separate volcanic fields within the Achayvayam-Valagin paleoarc (terrane) is different. On Karaginsky Island, volcanics of the moderate-potassium calc-alkaline and shoshonite series are widespread. On Ozernaya Peninsula, low-potassium basalts of the tholeiitic series are predominantly developed. The rocks of the Kumroch Ridge include low-potassium basalt-basaltic andesite, medium-potassium calc-alkaline and high-potassium shoshonitic. Volcanic rocks of the Tumrok Ridge are represented by low-potassium picrites and high-potassium trachybasalt-trachyandesites. In the Valaginsky Ridge, low-potassium tholeiitic, moderate-potassium calc-alkaline and shoshonite-latite series, as well as picrites and lamproitoids are distinguished. Isotopic (Sr, Nd and Pb) and geochemical composition of the rocks indicate their formation from a depleted mantle source within an ensimatic volcanic arc. It is shown that in the absence of significant differences in the material composition of rocks, regional differences are manifested. It is suggested that large-ion lithophile elements enrichment of volcanics may relate to fluids introduced into the melts during the melting of the supra-subduction mantle wedge. Issues of geodynamics of the region are considered.

Structural and geophysical indicators of neotectonics in the area of the continental margin of Côte d'Ivoire are represented in three interacting zones: oceanic, continental and transitional. Together with the time-varying gravitational field, they form a system in which neotectonic processes are enhanced due to their equatorial position. Seismicity is represented by dense clusters of events in the areas of junction of the Strakhov, Sao Paulo and Romansh oceanic transform faults with the continent and their overland continuation. Seismicity and gravity variations show the relationship of deep density changes to stress discharge in the area and the effect of volumetric forces on lithospheric blocks. Free air and isostasy anomalies along the shelf are segmented by the effects of vertical motions. Pull-apart depressions near the passive parts of transform faults indicate basement deformations in the interfault blocks and activation of shear displacements of dextral kinematics near the bend of the passive parts of the faults to the northeast from main oceanic azimuth. Segments with isostasy maxima on the shelf correspond to areas with coarser grain size granulometric composition, indicating leaching of fine sedimentary fraction from the bottom material.

A comparison of geophysical data along the segment of the Mid-Atlantic Ridge (MAR) between 10° N and 25° N and seafloor massive sulfides (SMS) ore objects revealed a number of regularities and relationships in their spatial distribution. SMS are grouped in areas with the following features: near subvertical «microplumes», into which the single axial anomaly of the MAR, determined by the seismotomographic model UU-P07, splits; maximums of Bouguer anomalies between the Vema and Kane transform faults, corresponding to dense mantle volumes and minimal magmatic debit; a pronounced alternation of spatiotemporal «voids» and «bands» of seismicity with a step of ~1.5°, comparable to the near-surface δVp minima; inversion of spreading rates asymmetry from east of the MAR to the west within 20° N and 24° N south of the Kane fault with nontransform south-oriented offsets; areas with positive correlation of the Bouguer anomalies and topography between 19° N and 22° N. The relation of SMS with the specified features of geophysical data forms a predictive basis for this type of objects.

The paper presents summary data on the historical activity of Ivan Grozny volcano (Iturup Island, Kuril Islands), including the results of our own studies of solfatar-hydrothermal and eruptive activity of the volcano since 2004. Using modern analytical methods, we obtained data on the chemical composition of the volcano rocks and pyroclastics of the explosive eruption in 2012–2013. The composition of the volcano rocks varies from andesites to daciandesites of medium potassium series. Pyroclastics of the 2012–2013 eruption corresponds to andesites with medium potassium content in terms of bulk chemical composition. The material composition of glasses according to microprobe data is much more acidic. The obtained values are similar to the geochemical compositions of the products of the 1973 and 1989 eruptions. Taking into account the prevailing wind regime dominating in the central part of Iturup Island, the hazard from ash fall of probable future eruptions of Ivan Grozny volcano was assessed, indicating the predominant spread of ash in the north-western, western and south-western directions.

Paleomagnetic dating of the Bolshesyrsky igneous area, a thick intraplate igneous complex of Khakassia, was carried out. The complex has not been dated due to the peculiarities of the stratigraphy and the lack of suitable rocks for applying the methods of absolute geochronology. The use of the paleomagnetic method has shown that the paleomagnetic pole of the red beds, which are intruded by sills and dikes of the Bolshesyrsky area, is close to the Silurian paleomagnetic poles of Siberia and Tuva and differs sharply from the Ordovician paleomagnetic poles of these areas. That is, red-colored rocks are Silurian, and subvolcanic rocks are post-Silurian. The sharp unconformable overlapping of the red-colored and volcanic strata with the Middle Devonian sedimentary trough without igneous rocks indicates that the age of the Bolshesyrsky complex is limited to the Silurian-Early Devonian interval. The genesis of the rocks of the Bolshesyrsky magmatic area was associated with the activity of the Early Devonian Minusinsk plume.

Ground temperature survey at three thermal fields of the southern group of the Kambalny volcanic ridge (South Kambalny Near, Central and Far thermal fields) was carried out. Their current state is characterized. The formation of temperature anomalies is determined by the peculiarities of the geological structure of each thermal field.The maps of temperature surveys obtained in 2021 and 1965 are compared. Changes in the conditions of convective heat flow unloading in the geologic structure of thermal fields are shown. The size of temperature fields on all geologic structures of the southern group of the Kambalny volcanic ridge have significantly increased over time. The area of the most warmed areas of thermoanomalies has increased. The maximum ground temperatures increased by 10 °С on average. Some thermoanomalies (boiling and pulsating water boilers and vapor-gas jets) increased their flow rates and (or) temperature. New warmed areas within the thermal anomalies were discovered.