We collected 217 seismograms with precritical reflected PKiKP and PcP waves, and obtained representative data on their travel times and amplitudes. These waves probe the boundary between inner and outer Earthʼs core in 4 areas beneath East Asia – Far East, Kamchatka Peninsula, Japanese Islands and Bering Sea – with spatial distribution by longitude from 120°E to 175°W. All differential travel time residuals relative to the three-dimensional LLNL-3D model in the mantle and crust and the ak135 model in the core have negative values from -2.0 s to -0.6 s, indicating a large-scale change in the inner core topography. The within-group variations in the differential residuals can be explained by small-scale changes in topography. The measured PKiKP wave amplitudes in all sounding regions have lower values than in the standard ak135 model. These features, except for the area below the Bering Sea, correspond to sinusoidal changes in the relief with a height of less than 1 km, or an alternation of hills with a height of 2 km and linear sections. The amplitude ratios of PKiKP and PcP waves for all groups of data, except for stations in Alaska, correspond in the first approximation to a density jump of 0.6 g/cm³, as in the ak135 model. Anomalously low PcP amplitudes of waves reflected from the outer core near coordinates 60°N and 180°E are revealed.

To summarize the data of long-term monitoring observations, the authors created models of intergeospheric interaction at the level: mantle-lithosphere; basement-sedimentary cover-modern relief; lithosphereatmosphere and, partially, ionosphere. In general, the authors conducted studies of 18 first-order tectonic nodes on the area of the Arkhangelsk region. The research included: - analysis of geological and geophysical materials, - digital modeling of the relief of the roof of the basement and the surface of the modern relief, - monitoring observations of the quantitative characteristics of abiogenic (electromagnetic emission, atmospheric pressure, inflow of deep gases, the rate of precipitation of solid and liquid precipitation, etc.) and biogenic processes (structure and composition of vegetation cover, the content of chemical elements in soils and vegetation cover) in tectonic nodes. Seismotomography data from the Canadian Diamond Province were also used to clarify the deep structure of the nodes. Analysis of the results obtained allows us to assert that the depth of tectonic nodes have 400 km or more. They are reflected in reduced temperature values in the lithosphere, from a depth of at least 200 km and asthenosphere and almost to the surface of relief; in terms of heat flux; in the structure of potential fields; in the structure of the Moho surface and the crystalline basement; in the power of the layers of the earth›s crust; in the modern geodynamic mode, in the macroseismic field, degassing and ionization of the atmosphere (up to the ionosphere). The structure of tectonic nodes has a fractal-like (tree-like) structure, similar to the structure of advective uplifts and diapirs of mantle asthenoliths. In the area of tectonic nodes, there is a correspondence of the structure of the deep layers of the earth›s crust in the basement, sedimentary cover and modern relief, as well as in the structure and properties of the vegetation cover. These processes are explained by geodynamic processes, deep degassing and the occurrence of induced magneto-telluric currents in the earth›s crust. Intergeospheric interaction in the areas of tectonic nodes is reflected in the structure of the atmosphere and, partially, the ionosphere. As a result of measurements of atmospheric pressure over tectonic nodes, the fact of a constant «deficit» of atmospheric pressure was established. We recorded an increased density of thunderstorms in the areas of tectonic nodes, as well as distortion of GPS signals. This scientific direction has a prognostic value in geoecological research. The results obtained are important to take into account when developing and analyzing geoecological studies of various scales and monitoring modern geoecological risks.

Structure and function of the coastal area geosystems summed up from interaction exogenous and endogenous factors during they evolution which able dramatically influence as on environmental situation and economical activity. Hydroisostasy fenomena, as one of an agent at the connection of sea level changes under Glaciation – Postglacial Ice melting and called by this subsequent changes of stress-strain condition of deep Earth was not involved in sufficient degree at the Russian coastal areas for science investigation activity. In this study made an attempt of analysis of results of palaegeographic researches and digital simulations for observation of coastal areas of Russians marine areas located in far-field zones to estimate hydroisostasy contribution to vertical neotectonic motions.There are demonstrated, that disturbance of isostatic balance as results of load change to the sea bottom by 120 meters water’s column during several thousands years able change dominated tectonic trend; the deformations could achieve to lower mantle’s layer; the rebound time of deformated coastal lines after load-unload by sea level changes during GlaciationPostlacial periods may require more time than time required for melting cover Glaciers; confirmed influence of costal line’s geometry to sea level altitudes. Considered the piculiarities of hydroisostsy manifistations depend on shelves width and depend of depth of Moho boundary. In the zone of tectonically active continental margins, a conclusion is made about the predominance of the subduction mechanism in neotectonic trends over the contribution of hydroisostasis. Investigated hydroisostasy influence on stressstrain condition of Earth crust complicated by regional scale fault zone.

Hydraulic fracturing is one of the main ways to increase the flow rate of an oil/gas field. There are methods in which hydraulic fracturing is used to study the stress-strain state of the reservoir being developed. This work was devoted to assessing the correctness of one of these methods, based on known fracture breakdown pressures, using laboratory experiments. Some poroelastic effects are not taken into account in the standard methods of determining the stress-strain state. In the paper, it was proposed to adjust the existing formula for determining the fracture breakdown pressure taking into account the backstress effect. This effect consists in the additional influence of the rupture fluid, which has filtered out from the well into the well surrounding rock mass, on the effective stresses acting on the borehole wall. As part of the work, theoretical estimates of the fracture breakdown pressure were made, which were compared with experimental fracture breakdown pressures. As a result of the data analysis, it was revealed that the critical stress on the wall of the well in laboratory experiments is achieved somewhat later due to the presence of the backstress effect, which made it possible to refine the existing formula for estimating the fracture breakdown pressure.

The paper considers a laboratory study of the interaction of a filtration flow with a poroelastic medium. As a result of the action of the filtration front, the skeleton is compressed, which leads to a change in permeability. The experiments were carried out on a two-dimensional optically transparent model at various pressures of the injected fluid. In the course of the study, a picture of the filtration process and deformation of the poroelastic medium was obtained, the velocities of the filtration wave, the dependence of the change in the speed of the filtration wave on time, and the width of its front were determined.

This paper presents the preparation and verification of a numerical model of the porous-elastic-plastic behavior of artificial material which is used for carrying out the laboratory modeling of hydraulic fracturing (HF). The developed numerical model is consistent with the results of laboratory experiments on hydraulic fracturing conducted earlier at Sadovsky Institute of Geosphere Dynamics of the Russian Academy of Sciences. The numerical modeling is performed to determine the opening and shape of HF fractures in porous-elastic-plastic artificial materials. For this purpose, the filtration-capacitive and elastic-plastic properties of the studied medium are taken into account in the work. A mathematical model consisting of a system of defining equations and a failure criterion, initial and boundary conditions are described, and the results of numerical modeling using the finite element method are presented. A three-dimensional numerical porous-elastic-plastic model of the rock was constructed based on the geometry of the sample. As a result of numerical modeling, distributions of equivalent plastic deformations, fields of pore pressure and stress changes were obtained, and the opening, shape and propagation velocities of HF fractures during their growth were determined for porous-elastic and porous-elastic-plastic models.

We present the results of studying the atmospheric temperature variability in the mesopause region and the NmF2 peak electron density during the winter sudden stratospheric warmings (SSWs) of different types in January 2013, February–March 2016, and February 2018. The analysis is based on the experimental data obtained from the complex of instruments of the Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences. To study the SSW effects, we used the method of complex analysis of atmospheric and ionospheric variability, which makes it possible to evaluate the manifestation of atmospheric wave activity in a wide range of altitudes of the upper atmosphere. It was found, that during the all analyzed SSWs, an increase in atmospheric and ionospheric variability was observed. Significant differences in the manifestation of wave activity at the heights of the mesopause and the ionospheric F2 region during SSWs of various types were also found.

This paper presents the results of modeling the generation and propagation of auroral hiss in the Earth’s magnetosphere and ionosphere. We analysed propagation conditions responsible for simultaneous observations of the auroral hiss in the auroral zone and polar cap region. We showed that considering the auroral hiss as a sum of acts of quasi-electrostatic waves generation distributed by altitude, latitude and wave vector azimuthal angle, these waves form two beams in the meridional plane. One beam propagates toward the equator from the field line where generation occurred and the other toward to the pole. This effect can cause simultaneous observations of the auroral hiss at two latitudinally separated observational sites. 

The results of calculations of deformation, fragmentation and deceleration of asteroids 1.5–5 km in size in the atmosphere of Venus are presented. The fraction of energy lost by asteroids during their passage through the atmosphere and the effective dimensions of an asteroid (or a cloud of its fragments) at the moment of impact on a solid surface are determined. It is shown that asteroids 1-2 km in size reach the surface of Venus in the form of a cloud of fragments with a diameter of 5–20 km, the kinetic energy of which is 10–1000 times less than the initial energy of the asteroid. Such impacts do not appear to result in the formation of classical single craters or crater fields, but may be responsible for the formation of dark and bright spots (splotches) observed on the surface of Venus.

The presented work proposes an ablation model describing the interaction of small meteoroids with the Earth's atmosphere, in which the meteoroid body is considered in two modifications: a solid and a porous body. An analysis is given of the obtained parameters for meteors with magnitudes from -2^m to +2^m obtained from optical observations.

In recent years, about 1200 of fresh meteoroid impact sites were discovered on Mars, they are single craters and crater fields. Due to the rarefied atmosphere of Mars (compared with Earth), the falling meteoroids are destroyed less, nevertheless, about half of them fragment in the Martian atmosphere and form crater fields of scattering (clusters). The study of crater clusters on Mars allows us to study the details of fragmentation, which cannot be detected on Earth. The initial results of numerical modeling of the interaction of a meteoroid with the atmospheres of Mars and Earth are considered. A comparison of fragmentation simulation results showed that the size of the scattering field on Earth is many times larger than on Mars. In the Earth›s atmosphere the fragments reach the surface without forming craters and there is atmospheric sorting of fragments. It is demonstrated that the final location of small meteorite fragments depends significantly on the chosen expression for the drag coefficient. Crater fields on Mars are largely determined by fragmentation and fragment dispersal, the effect of atmospheric sorting has little effect. The results obtained for the Martian atmosphere suggest that the serial implementation of the developed fragmentation model will allow to describe clusters and offer better methods for estimating the flight direction and properties of the impactor. 

It was previously shown that when using two powerful transmitters operating on two antenna arrays with a vertical radiation pattern, the phase centers of which are separated by a distance d with a carrier frequency spacing a moving source of low-frequency radiation appears in the lower ionosphere. The phase velocity of such traveling wave antenna coincides with the phase velocity of the main mode of the Earth-ionosphere waveguide at the frequency (F is the carrier frequency difference; h is the height of the ionospheric source above the Earth's surface). At this frequency, a maximum in the radiation amplitude is observed in the experiment. The paper considers a more general case when a HF interferometer operates with an arbitrary angle of inclination of the main beam of both emitters. It is shown that the frequency F strongly depends on the direction of the main beam and can vary over a wide range from units to 15 kilohertz. In this case, it is possible to match the velocity of the current wave in the source with the phase velocity of several first modes of the waveguide. In this case, it is possible to match the current wave of the source with the phase velocity of several first modes of the waveguide. It is shown that the frequency F strongly depends on the direction of the main beam and can vary over a wide range from units to 15 kilohertz. In this case, it is possible to match the velocity of the current wave in the source with the phase velocity of several first modes of the waveguide. We note that so far no experimental verification has been carried out in this formulation, although the technical capabilities of modern heating facilities allow such experiments to be carried out.