Geowebinar Insights

The study investigates variations in soil radon volumetric activity as an indicator of the stress-strain state of the Earth's crust and a short-term precursor to seismic events. The primary observation site is the South Kuril geodynamic polygon (Kunashir Island), supplemented by data from the Urals, Northern Tien Shan, and Northern Caucasus. The scientific problem lies in the strong influence of meteorological factors and the disruption of medium diffusion characteristics during conventional sampling, which hinders the recording of rapid geodynamic processes and correlating emanations with seismicity. To address this, a continuous monitoring method operating in a forced convection mode via active pumping of soil air from perforated boreholes was developed, alongside the application of Dobrovolsky's earthquake preparation strain model. Analysis of a continuous time series revealed that 89% of earthquakes with magnitudes exceeding 4 within a 500 km radius are preceded by radon anomalies exceeding background levels at least twofold. Events were categorized into far and near zones with distinct lag times relative to the anomaly maximum, and pore-closure and fracturing mechanisms were substantiated. The practical significance lies in establishing a real-time monitoring methodology for lithospheric block deformations to support short-term earthquake forecasting.

The study analyzes the spatiotemporal evolution of the seismic regime in focal zones and the three-dimensional structure of activated faults within the Altai-Sayan mountain region and adjacent areas of Mongolia. The research focuses on the focal zones of major earthquakes, including the Chuya, Aigulak, Ureg-Nur, Tuva, Khubsugul, and Busingol events, alongside seismic activations of the Shapshal Range and the Darkhad depression. The scientific problem lies in the inadequacy of describing regional post-seismic regimes as isolated aftershock sequences governed by the classical Omori decay law, requiring consideration of inter-block interactions. The methodology combines dense temporary seismic network observations, high-precision hypocenter relocation via the double-difference method, and automated waveform processing using the artificial intelligence algorithm EQTransformer. It is established that major seismic events trigger prolonged multiphase activations characterized by stepwise and pulsating energy release that encompasses adjacent ridges and basins while revealing unmapped faults. Contrasting regional impacts of mainshocks are demonstrated: temporary seismic quiescence following the Chuya earthquake versus intense surrounding activation, including the Darkhad swarm, after the Khubsugul event. The practical significance consists in refining geodynamic models and improving regional seismic hazard assessment.

The study investigates phase equilibria, crystal structures, and luminescent characteristics of solid solutions in the EuSc3(BO3)4 – GdSc3(BO3)4 double scandium borate system. The scientific problem focused on evaluating the feasibility of stabilizing the centrosymmetric R32 modification via cation substitution and optimizing luminescence intensity as a function of europium content. Samples were prepared via solid-state synthesis at 900–1250 °C and spontaneous flux crystallization of single crystals using a LiBO2–LiF eutectic solvent. Characterization was performed using X-ray powder diffraction with Rietveld structure refinement, differential thermal analysis, and photoluminescence spectroscopy. A non-quasibinary phase diagram featuring a melting minimum and a subsolidus miscibility gap narrowing with increasing temperature was established. The solid solutions were confirmed to crystallize in the C2/c and R3- space groups, consisting of connected ScO6 octahedra and (Eu,Gd)O6 polyhedra. Single crystals of EuSc3(BO3)4 demonstrate a photoluminescence quantum yield of 53%, high thermal stability up to 1390 °C, and pronounced chemical resistance to acids and alkalis, underscoring their prospective utility in photonic devices.

The study investigates the crystal chemistry and polymorphic transitions of the high-pressure hydrous phase kaliokemprite (KAlSi₃O₈·H₂O) at pressures up to 20 GPa using diamond anvil cell techniques and synchrotron radiation. The scientific problem lies in elucidating the structural transformation mechanisms of tetrahedral rings and incommensurately modulated twinning under high pressures, which do not follow the classical lock-in transition to a commensurate phase. The methods applied include single-crystal X-ray diffraction, diffuse scattering analysis, and calculation of ditrigonal rotation parameters for double hexagonal rings. It is established that above 8.5 GPa, a phase transition occurs involving symmetry reduction to a monoclinic pseudo-orthorhombic cell with incommensurate modulation. The study proves that the anomalous behavior of structural parameters and out-of-phase distortion of hexagonal rings are driven by the ordering of H₂O molecules within framework cavities. The practical significance consists in advancing the understanding of hydrous aluminosilicate phase behavior in deep geospheres.