Vol 23, No 2 (2023)

A generalization of historical data for more than 40 years on destructive cyclones observed on the coast of the South-East Baltic Sea has been made. According to the trajectories reconstructed using the HYSPLIT calculation model, cyclones with a northern trajectory, the so-called “diving” cyclones, were identified. A register of such cyclones has been compiled, showing their increasing occurrence: since the 80s of the last century, two such cyclones have passed (1981 and 1983), and since the beginning of thiscentury, over a 22-year period – 14. They differ in a significant acceleration length – about 1000 km from the Gulf of Bothnia to the southeastern coast of the Baltic Sea and have high potential energy. At the same time, atmospheric vortices cause wind waves up to 7–8 meters high. They are associated with significant, sometimes catastrophic, abrasion and retreat of coasts, especially the northern exposure, as well as the destruction of the coastal infrastructure of resort towns, including federal ones, historically concentrated on the northern coast of the Kaliningrad (Sambia) Peninsula of the Kaliningrad Region. The degree of destruction after the impact of each cyclone depends on the prehistory of its formation and development, the height of the surge of coastal waters, and the morphological features of the coast. There are two main scenarios for the development of seasonal storm activity. For example, in the winter season 2011–2012 and 2018–2019 after active cyclones with strong westerly winds of more than 20 m/s, which raised the sea level to +(40–60) cm, the approach of a “diving” cyclone with storm northerly winds caused an instant “splash” of the level up to +(100–120) cm above the ordinary (the marked maximum was 160 cm), which corresponds in order of magnitude to the heights of the beach. The second scenario is associated with the development of a series (cluster) of cyclones. It manifested itself especially clearly in the winter season of 2022, when four “diving” cyclones passed with short windows of good weather. The western cyclone was the final one. On the coast of the Kaliningrad Region, the level rose significantly. Both scenarios of the passage of “diving” cyclones are associated with the greatest storm damage to the coast of the Kaliningrad Region.

The Bazhenovo horizon of Western Siberia has traditionally been one of the objects most studied by geologists and geophysicists in recent decades in Russia. However, along with the more familiar "classical" structure, there are areas where gray-colored inclusions of sandy-silty-clayey deposits are present between the carbonate-clayey-siliceous rocks of the Bazhenovo Black Shales Formation. Such sections geologists call "anomalous". The paper describes the application of the spectral decomposition method for detailing the structure of anomalous sections zones of the Bazhenovo Formation or in another words Giant Sand injection Complex (GSIC) of the Ob river region. Combining the results of dynamic interpretation of 3D seismic data with well logging data for a vast fund of exploration and production wells made it possible to build a seismogeological model of the of the Ob river region GSIC in the Potochnaya area. The clue approach was tested on the Sporyshevskaya and Vyyntoyskaya, Vatinskaya areas, which were much less explored by drilling. The listed zones were formed at different geological times, belong to different regional clinoforms, but have common patterns of structure, which is reflected in the seismogeological model of the Ob river region GSIC. The model describes the distal and proximal parts of the intrusion, which were formed in the Neocomian time, when gravity-driven flows of sandy-silty material injected and spread inside high-bituminous Jurasic Bazhenovo formation Black Shales. Within the proximal part gravity-driven flows were accompanied by slumps of more clayey rocks. The dimensions of these flows and slumps, their location over the area are shown, their mapping in the 3D seismic data is discussed. In this work, we managed to get closer to solving the problem of predicting the development of sandy downward intrusions. There are oil reservoirs in the Ob river region GSIC, but they are insufficiently studied.

The analytical mathematical model is presented that describes one of the possible mechanisms for the occurrence of long-period seismic events that are often recorded near active volcanic centers. The feeding system of the volcano is modeled in the simplest form of a cylindrical channel filled with a compressible magmatic melt with the rheology of a Maxwell body. It is shown that such a magmatic body can experience harmonic damped oscillations, the damping coefficient of which is determined by the relaxation time of the magmatic melt. These fluctuations may appear as a response to a density perturbation caused by the influx of denser magma from deep layers or a change in pressure in the supply system of the volcano. The dependence of the natural oscillatory frequency on the physical characteristics of the magmatic melt and the geometric dimensions of the feed channel is shown. When the compressibility of the magmatic melt is taken into account, density perturbations depend on the size of the feeding system and are characterized by periodic oscillations, which are most pronounced near the channel axis. Oscillations are also experienced by the flow velocity component directed along the radius of the cylinder. The source mechanism of the long-period seismic events is discussed. The model is used to describe long-period oscillations recorded near Santiaguito (Guatemala).

The enormous development of the technology of raw material extraction drives the economic companies and technicians to make efforts to meet the needs of consumers. These efforts directly influence the nature, creating voids or cavities in the soil and subsoil inducing a structure disturbance and subsequently giving damages. A landslide of the Kef Essenoun phosphate deposit occurred in 2007 when large mass of rocks detached caused a number of undesired and negative effects. To analyze this deformation, a two-dimensional (2D) electrical tomography with the Wenner and Schlumberger device was deployed, using equipment of Syscal Pro 48 type for the implementation of an electrical profile, through a transect length of 140m with electrode spacing of 3m and a depth of investigation that measures 32m to the center. Data processing was performed using RES2DINV software and the results allowed mapping visible cracks with a high resistivity value of 890Ωm as well as low values of 6Ωm for marls and clay. In addition, to predict the extent of cracks (slip) and geological formations. These phenomena have been evidenced due to tectonic (rough terrain) on one side and sliding on the other.