Izvestiya, Physics of the Solid Earth最新文献

{"title":"Radiometric Studies of Magnetic Anomalies in the Middle Timan","authors":"A. Sh. Magomedova,&nbsp;V. V. Udoratin,&nbsp;Yu. E. Ezimova","doi":"10.1134/S1069351324701118","DOIUrl":"10.1134/S1069351324701118","url":null,"abstract":"<p>The article presents the results of an express radon survey on the territory of the Timan Ridge. The study objects were kimberlite pipes and local anomalies of the Middle Timan similar to them in the magnetic field. In the course of the study, the maps of the magnetic field of different scales were used to identify and sort magnetic anomalies similar to those of pipe-like bodies. Magnetic anomalies were distinguished using such qualitative characteristics as location, shape, size, sign, intensity, and gradient. Magnetometric and radon surveys were carried out to study the explosion pipes and magnetic anomalies. The magnetometric observations were conducted along a profile network in order to detect and determine the contour of the anomaly. The method of radiometric studies consisted in crossing the magnetic anomaly with a profile passing through three observation points—center, edge, and beyond the contour. The radiometric measurements within the Umbinskaya, Srednenskaya, Vodorazdelnaya and the Verkhnemezenskaya series of explosion pipes revealed the elevated values of volumetric radon activity (VRA) above the pipes. Thus, radon survey can be used as an additional search criterion included in the complex of geophysical works. Based on morphological variations in the magnetic field, several sites were distinguished in different tectonic structures of Middle Timan, within which radiometric studies of 68 magnetic anomalies were carried out. Moreover, 23 of the considered anomalies were characterized by the elevated VRA values. These anomalies, in turn, were divided into two promising categories that are of interest for further study. The first category includes anomalies with VRA values more than 1000 Bq/m³, the second category includes anomalies with VRA values from 450 to 1000 Bq/m³. This scatter of VRA values is associated, first of all, with the geological and tectonic position of the structure. The identified promising anomalies are very close in morphology to the pipe type, and geologically they can be caused by small intrusive bodies or explosion pipes. However, not only explosion pipes can be characterized by high VRA values, but this is also typical of individual magnetic anomalies caused by dikes and sills of basic, ultrabasic, and alkaline composition, as well as rocks enriched in radioelements. When setting tasks for studying magnetic anomalies aimed at searching for explosion pipes, the first step is to sort out such anomalies according to their location in the studied tectonic structures, morphology, and intensity.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1273 - 1289"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455485","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":"Detection and Estimation of the 1S1 Slichter Mode from IGETS Superconducting Gravimeter Network Data after the 2011 Tohoku Earthquake","authors":"M. P. Vinogradov,&nbsp;V. K. Milyukov","doi":"10.1134/S1069351324700940","DOIUrl":"10.1134/S1069351324700940","url":null,"abstract":"<p>The ₁S₁ Slichter mode is the longest-period mode of the Earth’s free oscillations, caused by oscillations of the Earth’s inner solid core relative to the outer liquid core. In this paper, the search for and estimation of the Slichter mode from the IEGTS superconducting gravimeter network data after the 2011 Tohoku earthquake are performed. In the course of the work, the theoretical calculation of the Slichter mode splitting parameters for the PREM model was made. The mode was estimated using an original algorithm based on the maximum likelihood method. The algorithm uses optimal data integration obtained from all 21 records of 16 gravimeters, which can significantly increase the signal-to-noise ratio at the output of the detection system. Three most probable estimates of the degenerate frequency of the mode and its splitting parameters were obtained, what allows one to conclude that the Slichter mode was highly likely to be observed after the Tohoku earthquake. The differences in density between the inner and outer cores of the Earth corresponding to the periods of the mode were determined.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1159 - 1170"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455561","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":"Spatiotemporal Sequences of Earthquake Epicenters as a Subspecies of Grouped Seismic Evens","authors":"A. V. Deshcherevskii,&nbsp;A. A. Lukk","doi":"10.1134/S1069351324700964","DOIUrl":"10.1134/S1069351324700964","url":null,"abstract":"<p>Linear sequences of earthquake epicenters (“chains”) related in space and time are studied. A new approach to understanding earthquake chains as a special kind of group (clustered) events is proposed. It is believed that clusters of group earthquakes with pronounced spatial anisotropy potentially represent the desired chains. Such chains are given the physical meaning of markers of activated tectonic faults. A formalized algorithm for the allocation of linear sequences of earthquake epicenters based on the proposed approach has been developed. The search for chains is conducted in the catalog of group earthquakes. Previously, single earthquakes (i.e., not included in clusters) are removed from seismicity. For this, a previously developed algorithm was used, focused on the selection of any interrelated events, and not only (mainly) aftershock and/or foreshock series (Descherevsky et al., 2016a). The proposed method of isolating earthquake chains has been successfully tested on earthquake catalogs of Garm, Iran and central Turkey. Chain maps are provided, and summary statistics of the chain field are discussed. As a rule, these chains can be compared with various tectonic disturbances, but a significant part of them are not tied to known structures. For the Garm district, the continuity of the results obtained with previously performed studies is shown. Like almost any method of analyzing seismic data, the earthquake chain algorithm has a significant number of configurable parameters. Within certain limits, you can vary the criteria for allocating group events, the minimum number of events in the chain and its minimum length, as well as the required level of straightness of the chain. However, all these settings primarily affect the total number of chains found in the catalog, and their location and orientation (azimuths) they almost do not depend on the algorithm settings. This allows us to consider the proposed analysis method as a fundamentally new way of extracting and visualizing information about the spatial and temporal organization of seismicity. A more detailed study of both the structure of earthquake chains and its changes over time in various seismically active regions of the world can contribute to a better understanding of the dynamics of the seismotectonic process.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1125 - 1150"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455579","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":"Spectral Characteristics for Earthquakes of Klyuchevskoy Group of Volcanoes","authors":"A. P. Molokova,&nbsp;A. A. Skorkina,&nbsp;V. B. Smirnov","doi":"10.1134/S1069351324700903","DOIUrl":"10.1134/S1069351324700903","url":null,"abstract":"<p>The Klyuchevskoy group of volcanoes is a unique research object, also from a seismological point of view. Classical high-frequency and long-period earthquakes of varying depths are being observed here, and the installation of temporary stations as part of the KISS project has made it possible to apply new methods to classify the observed seismicity. Two methods for determining seismic moments are used in the study. The spectral ratio method is used for the first time, which makes it possible to estimate the seismic moments of source spectra for the magnitude range <i>M</i>_w = 1–3. An independent assessment of seismic moments is also performed using a spectral method based on the level of low-frequency plateau of the amplitude displacement spectrum of body waves, and relation with the local magnitude is studied.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1092 - 1104"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455592","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":"Aftershock Area Assessment Based on the First Aftershocks at the Khibiny Deposits","authors":"A. Yu. Motorin,&nbsp;S. V. Baranov","doi":"10.1134/S1069351324700915","DOIUrl":"10.1134/S1069351324700915","url":null,"abstract":"<p><b>Abstract</b>—This paper examines the construction of an aftershock activity area in conditions of natural and mining-induced seismicity based after the data on the first aftershocks. The study area is apatite–nepheline deposits located in the southern part of the Khibiny massif. A significant number of variants of aftershock regions were investigated that differ in shape, location, and orientation. The size of the area has been determined by scaling based on physical and statistical characteristics calculated from both the main shock and the first aftershocks. The criterion based on an error diagram has been used to quantitatively compare a large number of different variants. As a result, the optimal area type has been selected, which showing the best results of the quantitative test based on seismicity data on the study area for 1996–2022. The technique can be used to predict the area of aftershock activity distribution at the Khibiny massif deposits after a natural–mining-induced earthquake based on operational processing data.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1105 - 1115"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455593","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":"Analysis of Solid Earth Tides Using Singular Spectrum Analysis: Implications for Earthquake Precursors","authors":"Ramya Jeyaraman,&nbsp; Venkatanathan N.","doi":"10.1134/S1069351324800012","DOIUrl":"10.1134/S1069351324800012","url":null,"abstract":"<p>The traditional field of research has been enriched by discovering and applying several unique approaches for extracting relevant information from a time series of Solid Earth tides for a specific location. This study focused on the impactful <i>Mw</i> 9.1 megathrust earthquake of December 26, 2004, in Sumatra-Andaman, which spans 13 earthquakes within a 75-kilometer radius from 1991 to 2021. Employing the univariate singular spectrum analysis (SSA) on Solid Earth tides (SET), a significant anomalous variation in the sixth component of empirical orthogonal functions (EOF) is identified. It is noted that the eigenvalue corresponding to this component exhibits a correlation with earthquake magnitude. Further, this study is extended to a broader spatial region to perform in-depth spatio-temporal analysis exclusively for the December 26, 2004 earthquake, by expanding spatial analysis to latitudes 2° to 5° N and longitudes 94° to 98° E through a sliding window method. A spatio-temporal analysis from 1995 to 2004 reveals distinct patterns preceding higher magnitude earthquakes, offering valuable insights for long-term forecasting. It has been correlated with foreshocks that occur to the same spatiotemporal extent. In a nutshell, singular spectrum analysis SSA of Solid Earth Tides emerges as a promising precursor for long-term earthquake magnitude prediction. Also, EOF alone is insufficient for accurately forecasting the magnitude, as the results show an inverse relationship with magnitude. Finally, it might be combined with other parameters like foreshocks for reliable earthquake forecasting.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1317 - 1339"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455489","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":"Three-Dimensional Model of the Ilmen Crustal Conductive Anomaly Based on Magnetotelluric Soundings","authors":"V. A. Kulikov,&nbsp;Iv. M. Varentsov,&nbsp;P. V. Ivanov,&nbsp;A. P. Ionicheva,&nbsp;S. Yu. Kolodyazhny,&nbsp;I. N. Lozovsky,&nbsp;T. A. Rodina,&nbsp;N. M. Shagarova,&nbsp;A. G. Yakovlev","doi":"10.1134/S1069351324700988","DOIUrl":"10.1134/S1069351324700988","url":null,"abstract":"<p>Since 2020, magnetotelluric/magnetovariational (MT/MV) soundings have been conducted in the triple-junction area of major segments (Fennoscandia, Sarmatia and Volga–Uralia) of the East European Platform. The study area extends to the north the SMOLENSK sounding array with inclusion of new observations from summer, 2023. Thus, the SMOLENSK array approaches from the south to the LADOGA sounding array. This article presents the results of MT/MV data invariant analysis, describes the selection of data ensembles for three-dimensional (3D) inversion, and analyzes the resulting 3D resistivity model.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 6","pages":"1171 - 1184"},"PeriodicalIF":0.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455562","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":"A Spherical Block Model of Lithosphere Dynamics and Seismicity: Current State and Development Prospects","authors":"V. L. Rozenberg","doi":"10.1134/S106935132470085X","DOIUrl":"10.1134/S106935132470085X","url":null,"abstract":"<p>A description of the evolution of a spherical block model of the dynamics and seismicity of the lithosphere is given. The main focus is on the current version and the introduction of a constructive automatic calibration (parameter selection) procedure to obtain the best approximation of key properties of regional and/or global seismicity. The paper presents some results of computational experiments.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 5","pages":"935 - 943"},"PeriodicalIF":0.9,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679641","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":"On the Use of Medium-Term Forecast Data for the Baikal Rift Zone in Seismic-Hazard Assessments","authors":"V. V. Ruzhich,&nbsp;E. A. Levina","doi":"10.1134/S1069351324700794","DOIUrl":"10.1134/S1069351324700794","url":null,"abstract":"<p>The article presents the general results of medium- and long-term earthquake forecasting with <i>K</i> ≥ 13 (<i>M</i> ≥ 5.0) in the Baikal rift zone. They were obtained in recent years through the joint use of the Prediction geoinformation system and the developed two-stage phenomenological model for the periods of preshock preparation of earthquakes. This model was created based on the analysis of seismological data on the preparation of the most dangerous local earthquakes that occurred in the Baikal rift zone. It is consistent with results obtained in the study of seismic regimes of ice shock preparation on the ice cover of Lake Baikal and in conducting field experiments on fault sections with the aim of clarifying the physical and mechanical conditions for the emergence of sources of seismic-range wave-oscillation generation. The paper provides an example of practical use of the obtained results of earthquake forecasting, as well as methods of clarifying seismic-hazard assessments in relation to infrastructure in the city of Angarsk, located 100 km from the seismically dangerous Main Sayan Fault (MSF), in the zone of which, during the analysis of the seismic regime, a “locked” segment with a seismic gap was identified. In accordance with its linear dimensions with a length of 60 km, according to two assumed equations of relationships <i>L</i>/<i>M</i>, estimates of energy potential were calculated, the maximum values of which correspond to the values <i>M</i>_max = 7.1 and 7.8. It is shown that the use of the obtained earthquake-forecast results helps to clarify the level of seismic hazard for the nearest time intervals of expectation of earthquakes with different values <i>M</i>_max. An example of assessing the current seismic hazard using a medium-term forecast for the infrastructure of the city of Angarsk is considered for possible seismic tremors from the south-eastern section of the MSF zone for the next 10 and 50 years. When compared with the OSR-16 map, it is shown that the calculations carried out indicate a relatively lower level of seismic hazard for the city of Angarsk, with waiting times of 10 and 50 years.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 5","pages":"870 - 878"},"PeriodicalIF":0.9,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679635","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":"A Numerical Study of the Phenomenon of Seismic Slip on a Fault as a Result of Fluid Injection","authors":"V. Yu. Riga,&nbsp;S. B. Turuntaev","doi":"10.1134/S1069351324700848","DOIUrl":"10.1134/S1069351324700848","url":null,"abstract":"<p>The issue of the occurrence of seismicity induced by injection of fluid into the subsurface is considered. A model of nested fractures is presented, which allows simulating the process of fluid filtration in a rock containing fractures or faults, taking into account the change in the filtration properties of the latter during the change in pore pressure. The process of fault deformation is described using the displacement discontinuity method. The model is used to analyze the effect of fluid injection in the immediate vicinity of a fault on its subsequent deformation. The transition of fault slip from aseismic to seismic is investigated when the parameters of the friction law or fluid injection parameters change. Conditions have been found under which seismic slip may occur within the framework of the proposed model.</p>","PeriodicalId":602,"journal":{"name":"Izvestiya, Physics of the Solid Earth","volume":"60 5","pages":"923 - 934"},"PeriodicalIF":0.9,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679640","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}