The article examines the consequences of scenario earthquakes for settlements of Krasnodar Krai, including the cities of Krasnodar and Tuapse. The aim of the study is to provide realistic estimates of damage and risk indicators resulting from predicted strong and felt earthquakes in the study area. The tools and simulation methods used to assess the potential impact of scenario earthquakes on buildings and the population of the region are described. The paper presents methodological materials and the results of calibrating seismic intensity attenuation models based on an analysis of historical seismicity data for the region. Baseline data have been updated to account for the specific building stock characteristics of Krasnodar Krai settlements. Maps of potential damage to the building stock, maps of individual seismic risk, and economic vulnerability at the regional and urban levels are presented. Particular attention is paid to the rapid modeling of the consequences of a felt earthquake that occurred near the city of Krasnodar on January 24, 2024. This event was used to verify the models and assess the accuracy of the obtained results. It is confirmed that the models adequately reflect the extent of potential damage and meet the specified requirements. The obtained data can be used for planning risk mitigation measures and increasing regional resilience to potential natural disasters.
This study was performed within the framework of the problem of diagnosing, monitoring, and predicting the state of geotechnical systems and natural objects. It focuses on the substantiation and laboratory testing of an approach for establishing quantitative relationships between the parameters of stochastic fields in geo-objects under heterogeneous stress conditions. Experiments on diametrical compression of rock disk specimens were conducted with synchronous recording of microdisplacements on their surfaces using digital image correlation. Interpretation of the obtained data allowed us to identify emerging surface microfractures at each loading stage. It was established that even at the initial stage, statistically significant relationships arise between disturbances (characterized by the number of microfractures per unit area) in different parts of the specimen, and the closeness of these relationships increases with growing load. Correlations were found between the load level and the number of microfractures in different parts of the specimen, which enable predictive assessments of the disturbance of the latter.
Information on an earthquake focal mechanism is essential for assessing the expected ground effects of seismic events. This paper investigates the distribution of focal mechanisms in the Kuril–Kamchatka subduction zone based on the GCMT catalog for the period of 1976–2020. The distributions of mechanism parameters are analyzed separately for intraslab, interplate, and shallow crustal events. A set of maps, showing the most probable focal mechanisms for each earthquake type within the Kuril–Kamchatka subduction zone, is proposed as the first step toward constructing a probabilistic model of focal mechanism distribution.
This study presents an analysis of direct numerical modeling of fluid injection in the vicinity of an active tectonic fault. The objective is to refine the initiation criteria for induced seismic events by considering both the absolute pore pressure and its rate of change. We simulate a scenario of fault hydraulic unloading where elevated pore pressure reduces effective normal stresses and initiates slip along fault segments. Utilizing a rate-and-state friction framework, we analyze the transition from steady (aseismic) slip to an unstable, seismogenic regime as a function of the pore pressure buildup rate. The results demonstrate that the characteristics of induced slip are governed not only by the pore pressure level reached but also by its rate of increase. Within the considered modeling framework, the final slip zone length scales almost linearly with the initial length of the unstable fault segment, while the maximum slip velocity is highly sensitive to the pore pressure growth rate, exhibiting an exponential increase followed by saturation. A comparative analysis of different methodologies for estimating seismic moment and equivalent magnitude reveals a consistent threshold structure in the relationship between magnitude and the pore pressure growth rate.
This article examines the anomalously short recurrence interval of the largest subduction earthquakes in southern Kamchatka. The Kamchatka megaearthquake of July 29 (30), 2025, with Mw = 8.8, occurred within the focal zone of the Great Kamchatka Earthquake of November 5, 1952, which corresponds to an interseismic interval of 73 years. Megaearthquake recurrence intervals typically last hundreds of years or more. For example, in the central part of Honshu Island, an event comparable in magnitude to the Tohoku megaearthquake of March 11, 2011, occurred in 869. To explain this feature, an interpretation based on the key-block model is proposed, linking the stress accumulation and release regime with the degree of segmentation of the frontal wedge of the overlying lithospheric plate. Based on an analysis of morphostructural and seismological data, it is shown that the southern part of the Kamchatka frontal wedge is characterized by signs of a more consolidated structure, while more segmented areas are characterized by partial intermediate stress releases. Geomechanical modeling results confirm that zones of elevated Coulomb stress in the consolidated wedge form a more cohesive region and reach their ultimate limit state more quickly. These results suggest that the increased consolidation of the southern Kamchatka frontal wedge may be one of the factors contributing to the abnormally frequent occurrence of megaquakes in this segment of the subduction zone.
