Izvestiya, Physics of the Solid Earth最新文献

{"title":"Robustness of Focal Mechanism Solutions for Strong Earthquakes in the Southern Baikal Region (Mw ≥ 4.9, 2020–2023) Depending on Methods and Crustal Velocity Models","authors":"V. I. Melnikova,&nbsp;A. I. Filippova,&nbsp;N. A. Gileva,&nbsp;M. A. Khritova","doi":"10.1134/S1069351326700370","DOIUrl":"10.1134/S1069351326700370","url":null,"abstract":"<p>We consider the influence of different methods and crustal velocity models on the focal mechanisms of strong earthquakes (<i>M</i>_w ≥ 4.9) in the Southern Baikal Region in 2020–2023. For each seismic event, source parameters were estimated using three approaches: from <i>P</i>-wave first-motion polarities (FM method), by inverting waveforms from regional broadband seismic stations (ISOLA method), and from the joint inversion of surface wave amplitude spectra, recorded at remote broadband stations, and <i>P</i>-wave first-motion polarities (SWP method). Depending on the location of the earthquake epicenter, its source parameters were estimated using a corresponding set of crustal velocity models. In total, seven velocity models obtained by different authors were considered. The results showed that, within a single method, different crustal velocity models do not significantly affect the stability of the focal mechanism solutions (the Kagan angle Ф, an angle in 3D space between two focal mechanisms, is generally less than 10°). This is because the wavefield recorded at regional (∆ &gt; 100 km) and teleseismic distances, with wavelengths significantly exceeding the rupture length, is not sensitive to the details of the velocity structure of the geological medium. When comparing solutions obtained by different methods, a slight variation in the estimated parameters is also observed (most Ф-values are less than 30°). Thus, the example of strong earthquakes in the Southern Baikal Region (<i>M</i>_w ≥ 4.9, 2020–2023) demonstrates that robust estimates of source parameters can be obtained using simplified crustal velocity models. This study also confirms the potential of tensor solutions based on the joint use of teleseismic and regional data. In this case, the hypocentral depth and energy characteristics are determined along with the focal mechanism solution.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"513 - 532"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Оn Some Methods of Separate and Joint Restoration of Potential Geophysical Fields","authors":"A. G. Yagola,&nbsp;I. E. Stepanova,&nbsp;A. S. Leonov,&nbsp;D. V. Lukuyanenko,&nbsp;A. V. Shchepetilov,&nbsp;A. N. Levashov,&nbsp;A. V. Gorbachev","doi":"10.1134/S106935132670045X","DOIUrl":"10.1134/S106935132670045X","url":null,"abstract":"<p>Two approaches to solving inverse problems of potential fields using the measurements of the field components and their gradients are considered. Both approaches find the sources of the fields on some two-dimensional varieties. This reduces inverse problems to a two-dimensional formulation, ensuring uniqueness of the solution in a number of cases and accelerating computational procedures. By solving such problems for manifolds located at varying depths, valuable input for geophysical interpretation can be obtained. The proposed methods are suitable for both separate and joint inversion of gravity and magnetic fields. Both approaches guarantee the uniqueness of the obtained solutions and their stability with respect to data perturbations. The first approach to the inverse problems is based on the variational scheme of <i>S</i>-approximation and is implemented using the method of Lagrange multipliers. It allows for localization of sources on several manifolds of different nature. Using field gradient data, this approach can recover not only the sources but also the complex spectra of the fields themselves on one or multiple manifolds. The method is applicable to the processing of local geophysical data as well as for regional and global-scale analyses. The second approach is based on replacing the original inverse problem matrix (which may be ill-posed or even unique) with a nearby matrix, close in norm, that possesses a better condition number. This significantly improves the stability of the resulting approximate solutions, often by several factors. An algorithm, termed the MPMI algorithm (Minimum pseudoinverse matrix with improved condition number), is proposed for the numerical implementation of this approach. The methods for solving inverse problems of potential fields presented in this paper are applied to the processing of real, heterogeneous geophysical data.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"546 - 564"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Properties of Dynamical Systems Driving Seismicity in Kamchatka and Japan","authors":"A. S. Cherepantsev,&nbsp;V. B. Smirnov","doi":"10.1134/S1069351326700424","DOIUrl":"10.1134/S1069351326700424","url":null,"abstract":"<p>Analysis of seismicity in Kamchatka and Japan demonstrates that, within the framework of nonlinear dynamical systems, it is possible to estimate the key parameters of a system of equations acting as a “generator” of the seismic regime. Based on the introduced seismic parameter, estimates are obtained for the embedding dimension and the fractal dimension of the phase portrait for the dynamic seismicity system. The former indicates the dimension (the required number of equations) of the dynamical system needed to describe the seismic regime, whereas the latter reflects the degree of chaos (randomness) in the system’s solution. This analysis spans a wide range of energy, spatial, and temporal scales. A distinct shift in the properties of such a system generating the dynamics of seismicity is observed in association with the Tohoku megaearthquake.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"414 - 429"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methods for Estimating the Thickness of Productive Intervals and Water Saturation in Oil Deposits Using Seismic Background Noise","authors":"I. Ya. Chebotareva,&nbsp;E.-D. Rode","doi":"10.1134/S1069351326700412","DOIUrl":"10.1134/S1069351326700412","url":null,"abstract":"<p>The article presents the results of remote determination of the rock saturation type and estimation of the total thickness of productive intervals based on recordings of natural seismic background noise. Field data were processed using both methods previously proposed by the authors and new ones. These methods are based on the well-known empirical phenomenon—the appearance of a positive spectral anomaly in the seismic background above a hydrocarbon deposit in the 1–10 Hz frequency range. The field data recorded near wells and along the profile in mature fields in the desert of southeastern Kuwait were analyzed. The developed methods were found to be equally effective for analyzing hydrocarbon deposits with both carbonate and terrigenous reservoirs at different stages of development. Empirical mode decomposition allowed for the separation of the oscillating and trend components of the productive interval thickness estimates, which characterize different geological and geophysical features of the study area. The maxima of the trend component mark the position of large oil-bearing geological blocks, while the minima correspond to inter-block boundaries with no oil content. The oscillating modes reflect local features of the degree of rock oil saturation. The proposed methods and techniques are valuable tools in oil and gas exploration for constructing maps of total productive interval thickness and selecting the most promising drilling locations. They can also be applied in the development of mature fields to identify water breakthrough zones, delineate water-flushed compartments, and locate poorly drained, oil-filled areas. The new acoustic method for detecting water saturation of rocks is promising for developing technologies to prospect for underground high-quality drinking water sources in arid and industrial regions, which is an urgent modern problem.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"565 - 579"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Double-Couple Tectonic Earthquakes","authors":"E. A. Marshakova,&nbsp;V. B. Smirnov,&nbsp;V. O. Mikhailov","doi":"10.1134/S1069351326700369","DOIUrl":"10.1134/S1069351326700369","url":null,"abstract":"<p>A global systematic analysis of seismic moment tensors of tectonic earthquakes was conducted using the GCMT catalog period from 1976 to 2025. To identify earthquakes with sources inconsistent with the double-couple model (NDC earthquakes), we applied a method that estimates the angle between the slip vector and the rupture plane based on the principal values of the seismic moment tensor while accounting for their uncertainties. Out of 68е540 analyzed earthquakes with <i>M</i>_w ≥ 4.5, 3.4% were classified as NDC events based on fairly strict selection criteria. The spatial and depth distributions of these earthquakes were examined alongside their correlations with focal mechanism type and tectonic setting. Within mid-ocean ridges, the sign of the parameter characterizing the deviation from the DC model differs systematically between spreading and transform segments. In subduction zones, several depth-dependent maxima in the proportion of NDC events were identified. The NDC component is least pronounced for thrust mechanisms and most pronounced for oblique-slip events. These results demonstrate that variations in the NDC component are systematic, reflecting the underlying physical processes that drive its generation.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"441 - 451"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148459063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Fracturing on the Elastic Properties of Sylvinite: Comparison of Effective Media Theory Methods Based on X-ray Computed Microtomography","authors":"I. A. Panteleev,&nbsp;A. A. Baryakh,&nbsp;D. V. Lozhkin,&nbsp;A. S. Sokolov","doi":"10.1134/S1069351326700485","DOIUrl":"10.1134/S1069351326700485","url":null,"abstract":"<p>Comparison of several effective medium theory methods was performed to describe the degradation of the elastic moduli of red sylvinite samples subjected to cyclic uniaxial compression with an increase in maximum load after each cycle. The predicted values of the Young’s modulus of red sylvinite after each loading cycle were determined using X-ray computed microtomography (CT data). The dependence of the deformation characteristics of red sylvinite on the maximum load in a cycle was experimentally determined. At loads up to 10 MPa, the tangent modulus of deformation changes insignificantly (≤10%); after a cycle with a load of 20 MPa, its significant degradation is observed, on average, by 32%. Analysis of CT data for sylvinite samples showed that microcrack formation begins in sylvinite conglomerates and at the boundaries with halite, and with increasing load, it spreads to halite conglomerates. It was found that the change in the tangent modulus of deformation of sylvinite linearly correlates with the volume fraction of microcracks. Two methods are proposed for estimating microcrack density from CT data: based on their maximum size and based on the radius of penny-shaped cracks of equivalent volume and lateral surface area. To describe the dependence of the effective Young’s modulus on the maximum load in a cycle, the following methods of effective medium theory were tested: the Mori–Tanaka method, the differential effective medium method, and the self-consistency method. It was established that the differential effective medium method and the self-consistency method with the crack density assessment by the first method give underestimated values of the average effective normalized Young’s modulus, starting from moderate loads, while the Mori–Tanaka method gives overestimated values. It is shown that the self-consistent method using the equivalent penny-shaped crack model to estimate the crack density gives acceptable results for predicting the effective Young’s modulus at a microcrack density of up to 0.5.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"603 - 613"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148459062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seismogenic Spots in the Kamchatka Subduction Zone: Geological and Geophysical Perspective","authors":"A. A. Ostapchuk,&nbsp;I. I. Nugmanov,&nbsp;K. G. Morozova,&nbsp;O. V. Bergal-Kuvikas","doi":"10.1134/S1069351326700394","DOIUrl":"10.1134/S1069351326700394","url":null,"abstract":"<p>The evolution of tectonic faults and localization of strong earthquake sources are controlled by the configuration and rheological properties of tectonic asperities. Seismogenic spots are a seismic manifestation of tectonic asperities and can be identified on the basis of spatiotemporal analysis of seismicity, namely, they represent topologically dense spatial groups of background seismicity. This study investigates the seismicity patterns of the Kamchatka Subduction Zone (KSZ), where the oceanic Pacific Plate subducts beneath the continental Okhotsk Plate along the Kamchatka Peninsula. We used the regional seismic catalog from the Kamchatka Branch, Geophysical Survey, Russian Academy of Sciences, which includes 38 886 events recorded from January 1, 1990, to September 14, 2025. The magnitude of completeness (<i>M</i>_c) for the catalog is 3.0. Seven seismogenic spots, with characteristic sizes ranging from 150 to 250 km, are identified within the KSZ. The structuring of these spots is shown to persist throughout the entire 35-year observation period. The boundaries of the seismogenic spots are consistent with the structural features of the subducting Pacific plate. Within these seismogenic spots, 18 out of 23 epicenters of earthquakes with magnitudes greater than 7 that have occurred in the region since 1900 are localized. The source structure of the strongest Kamchatka megaearthquake <i>M</i>_w 8.8 on July 29, 2025, which reflects the configuration of tectonic asperities, is in full agreement with the configuration of the KSZ seismogenic spots.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"399 - 413"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-Domain Electromagnetic Sounding in Arctic Water Areas","authors":"D. A. Alekseev,&nbsp;E. I. Balikhin,&nbsp;A. A. Goncharov,&nbsp;A. Yu. Gunar,&nbsp;N. I. Ignatyev,&nbsp;A. V. Koshurnikov,&nbsp;P. Yu. Pushkarev","doi":"10.1134/S1069351326700461","DOIUrl":"10.1134/S1069351326700461","url":null,"abstract":"<p>The time-domain electromagnetic (TDEM) sounding method is effectively used in shallow marine waters all over the world, including the Arctic shelf, where the main object of study is the permafrost layer. A generalized geoelectric model of the Arctic shelf section is presented, which is based on the results of studies conducted by the authors, using archival information from available sources, and contains three main layers: unfrozen bottom sedimentary layer, permafrost layer and subpermafrost layer. Algorithms for solving direct and inverse problems of TDEM are briefly described, including those using the polarization properties of the layers. Typical curves of apparent electrical resistance of TDEM (TDEM curves) are constructed, corresponding to geoelectric models of Arctic waters for three zones: the open sea, the transition zone, and the river mouth. The curves qualitatively reflect the dependence of resistance on depth, except for the case of the most highly resistive section containing a polarizing layer, when the curve is strongly distorted. A series of model experiments were carried out to solve the inverse problem within the framework of a five-layer model. It was shown that when obtaining possible equivalent models that differ from the true one (created by the authors using known parameters), their number can be reduced by fixing the parameters of the water layer, thereby improving the modeling results. The effects associated with the polarizability of the subpermafrost layer, which significantly complicate interpretation, but quickly fade with an increase in the thickness of the seawater layer, were analyzed.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 3","pages":"580 - 588"},"PeriodicalIF":0.7,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148458993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forecast of Solar and Geomagnetic Activity Based on Advanced Nonlocal Correlations","authors":"S. M. Korotaev,&nbsp;V. O. Serdyuk,&nbsp;N. M. Budnev,&nbsp;E. O. Kiktenko,&nbsp;I. V. Popova,&nbsp;Yu. V. Gorohov","doi":"10.1134/S1069351326700217","DOIUrl":"10.1134/S1069351326700217","url":null,"abstract":"<p>The phenomenon of weak but finite quantum entanglement at the macrolevel leads to nonlocal correlations of almost isolated random dissipative processes. Long-term experiments studying macroscopic nonlocal correlations between random dissipative heliogeophysical processes and random processes in detectors have revealed the important properties of macroscopic entanglement predicted by quantum absorber electrodynamics. These correlations have retarded and advanced components, whereby, due to the asymmetry of the absorption efficiency of the corresponding components of the Wheeler–Feynman electromagnetic field by the medium, the advanced correlation exceeds the retarded one. Although advanced correlation corresponds to reverse-time causality, for random processes this does not lead to paradoxes. This kind of advanced correlation allows forecasting the random components of solar and geomagnetic activity by observing a probe process in a detector isolated from classical local influences. Long-term series of observations under laboratory–observatory conditions and during the deep-water experiment in Lake Baikal have proven the possibility of such forecasts with a lead time of several months and with an accuracy sufficient for all practical purposes.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 2","pages":"380 - 388"},"PeriodicalIF":1.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetotelluric Methods in Surface Electrical Prospecting for Ore","authors":"V. A. Kulikov,&nbsp;N. M. Shagarova,&nbsp;A. G. Yakovlev","doi":"10.1134/S1069351326700230","DOIUrl":"10.1134/S1069351326700230","url":null,"abstract":"<p>Magnetotelluric (MT) methods have emerged as a primary tool in ground-based geophysical surveys for ore mineral exploration. MT methods are particularly effective for investigating metallic ore deposits, which, characterized by high electrical conductivity, can be detected and studied via electromagnetic (EM) sounding. The widespread use of MT technologies in ore exploration is driven by the practical implementation of a high-frequency modification of the method—audio magnetotellurics (AMT). Beyond the direct detection of ore bodies, MT methods facilitate the resolution of indirect geological objectives, such as delineating intrusive massifs, mapping fault zones, and identifying zones of hydrothermal alteration. This paper reviews the application of MT methods integrated with other electrical exploration techniques for solid mineral prospecting. The analysis summarize the experience of regional, prospecting, and target-scale exploration projects conducted by the Severo-Zapad company.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"62 2","pages":"276 - 285"},"PeriodicalIF":1.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148104232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}