A geomechanical model of pockmark formation on the seabed resulting from gas hydrate decomposition has been developed. The process of destruction and formation of pockmarks occurs in a medium whose behavior is described by a nonlinear creep model combined with a yield  criterion dependent on internal friction. Constitutive relations for an elastic-viscous-plastic medium with a temperature-dependent power law of creep are used. The law of non-associated plastic flow with the Drucker–Prager limit condition and softening is used to describe the destruction of the medium. Softening leads to the development of instability of viscoplastic flow and localization of shear deformation in narrow zones, along which destruction occurs. Analysis of the development of deformations and stresses showed that shear deformation is localized on the inner contour of the dome-shaped cap, forming a narrow conical zone. After it reaches the surface, cohesion drops to zero and the pressure pushes the material to the surface, completing the formation of a crater. The time it takes for the conical surface to form depends on the pore pressure in the inclusion. If the pressure does not exceed the critical value, the stresses in the cap do not reach the strength limit, the fracture surface does not form, and the pockmark does not form.

We investigate the evolution of geophysical fields for spherical and Cartesian models of thermochemical mantle convection with floating continents, oceanic plates and phase transitions, with mantle heated from below and from internal  heat sources. Drifting continents remain on the surface for a long time due to increased buoyancy. In this paper we consider the stage of the supercontinent and the beginning of its disintegration. After the formation of the supercontinent, mantle flows are rearranged and a group of mantle plumes is formed under it, as well as an extended surrounding subduction zone. The hot heads of plumes located under the supercontinent increase in size due to the thermal insulating effect of the supercontinent and spread out under its lower boundary, causing tensile stresses in the supercontinent and overlithostatic compressive horizontal stresses in the subcontinental mantle. Tensile overlithostatic horizontal stresses inside the supercontinent reach 200 MPa for Cartesian two-dimensional model and up to 60–00 MPa for the spherical model, whereas overlithostatic compressive horizontal stresses in the subcontinental mantle are found under the supercontinent up to 110 MPa for the two-dimensional model and 40–80 MPa for the spherical model. Due to the lack of consideration of sphericity and the difference in the areas of the upper and lower surfaces of the mantle, two-dimensional models significantly overestimate the stresses in the upper mantle and continents compared with spherical models. 

A luminous object observed in Spain in the vicinity of Santiago de Compostela on January 18, 1994 and described by eyewitnesses had characteristic features that are inconsistent with the typical flight of a bolide in the atmosphere. Namely, the object was moving at altitudes from ~ 26 to ~ 3 km at an angle of 18° to the Earth's surface with a low speed of 1–3 km/s, and its glow was bright. This phenomenon has not received a reasonable explanation. In this paper, estimates are made of the possible processes and parameters of the cosmic body whose fall could have caused this event. A scenario is proposed in which a stony asteroid several meters in size enters the atmosphere with the minimum speed of ~ 11.2 km/s. The body decelerates to 3 km/s at an altitude of ~ 26 km due to its disintegration into fragments and a gradual increase in the cross-sectional area of the fragment swarm, as in the well-known pancake models. Then the fragments collimate into one or more chains, due to which they overcome atmospheric resistance on their path of about 75 km and slow down to a speed of ~ 1 km/s only at an altitude of 3 km. The glow is caused by thermal radiation from the surface of numerous fragments heated to a temperature close to the solidus temperature. The mechanism of fragment collimation proposed to explain the event requires further substantiation and study.

There are two ultimate impact scenarios for large space bodies: a crater-forming impact, when almost all of the initial kinetic energy of the body goes to the formation of a crater, and the “meteor explosion”, in which the energy is released in the atmosphere. In transient scenarios, the loss of energy in the atmosphere is significant, but the body reaches the Earth›s surface with enough energy to form a crater. The hazardous consequences of such impacts must be assessed with this energy separation in mind. On the basis of the performed calculations and a simple quasi-empirical model of the interaction of space bodies with the atmosphere, scaling relations for determining the fraction of energy lost by a space body during a passage in the atmosphere in transient modes are proposed. The results provide an opportunity to properly describe the appearance and growth of a crater as the impactor size increases, which is currently described incorrectly in online calculators of asteroid-comet hazard, and to adjust the estimates of other dangerous consequences for transient variants.

Craters formed by an asteroid impact on the Earth’s surface are characterized by the presence of an anomaly in the magnetic field. Numerical modeling of the anomalous magnetic field allows us to study the crater along with the methods used in geological exploration. Craters that are close in size have morphological similarities, which allows for a comparative analysis of magnetic anomalies of different craters. It is shown that they correspond to the general picture of the magnetic anomaly of the crater under study and lead to the conclusion that there is a layer of impactites in the crater bed and in the central hill buried under the sedimentary cover. Based on the modeling results, the average magnetic susceptibility of the target rocks is estimated at 3·10^-4 SI.

We discuss a new approach to the development of a comprehensive prognostic feature of atmospheric fronts causing dangerous atmospheric phenomena in the form of hurricanes, squalls, severe thunderstorms and volley precipitation. Our approach is based on the analysis of joint variations of meteorological parameters of the atmosphere and geophysical fields (primarily electric and magnetic fields) in the period preceding the arrival of the front and the onset of the most intense phase of these dangerous phenomena. It is shown that 5‒8 hours before the arrival of powerful atmospheric fronts of the 2nd kind, variations in the geophysical characteristics of the surface atmosphere are observed, which can be used as the basis for the formulation of prognostic signs of dangerous atmospheric phenomena. The data provided can be used to prevent negative consequences and increase the reliability of short-term forecasting of negative effects of atmospheric phenomena.

The mass distribution of meteoroids is described by a power law, where the degree exponent is the parameter s. The parameter s of selected meteoroid streams (Perseids, Geminids, and Orionids) was calculated for 2021–2022 from the Global Meteor Network (GMN) data. Parameter s estimate was based on photometric estimates of meteoroid masses and mass estimates from empirical relationships. The variation of the s estimates during the period of activity of selected meteoroid streams was analyzed. It was found that  the influence of different estimates of particle masses on the parameter s can reach 20%.

The ablation model is used to estimate the physical parameters of millimeter-sized meteoroids. In the ablation model used, the energy of the incident flow is spent only on the loss of mass of the meteoroid. The selection of parameters (size and density) of meteoroids for the reproduction of light curves is carried out using an automated approach. The influence of ablation heat on the mass, density and size of meteoroids was investigated. The estimates of meteoroid parameters obtained within the framework of this model are compared with estimates based on empirical relationships and with estimates based on another ablation model.

The article presents the results of experiments aimed at physical modeling of liquid filtration in the body of a dam made of bulk soil. The paper examines the stability of such a structure when exposed to a filtration flow. The proposed model allows visualizing the processes of wetting and saturation of the body of a bulk dam with subsequent mass transfer of particles and changes in its geometry. Parameters are identified that allow determining the point on the slope where the soil is in a limiting state and instability may occur.