pure and applied geophysics最新文献

{"title":"Assessment of Surface PM2.5 Concentrations over India using Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) Reanalysis Data","authors":"Sumit Singh,&nbsp;Amarendra Singh,&nbsp;Atul Kumar Srivastava,&nbsp;Virendra Pathak,&nbsp;Ajay Kumar,&nbsp;Vivek Singh","doi":"10.1007/s00024-025-03666-6","DOIUrl":"10.1007/s00024-025-03666-6","url":null,"abstract":"<div><p>Particulate matters with a diameter of 2.5 μm or smaller (i.e. PM_2.5) are critical component of air pollution that has significant impacts on human health and the environment. The study underscores the utilization of the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis data to evaluate surface PM_2.5 concentrations as well as its sub-species across India during the period from 2018 to 2021. MERRA-2 and ground-based AERONET-derived Aerosol Optical Depth (AOD) over Kanpur, Jaipur, Pune, and Delhi shows a significant correlation of 0.70, 0.74, 0.82 and 0.65, respectively. The study also reveals a complex relationship between PM_2.5 and its sub-species with the meteorological factors, which was found to vary seasonally, specifically, during the winter season. The Indo-Gangetic Plains (IGP) experiences pronounced seasonal variations, with peak concentrations in winter and post-monsoon seasons. This study also explores the impact of India's COVID-19 lockdown on air quality, revealing a consistent reduction in PM_2.5 and its sub-species during different lockdown phases in 2020 compared to previous and subsequent years. By leveraging high-resolution atmospheric data, this research advances our understanding of pollution patterns, sources, and trends, offering valuable insights for air quality management and policy formulation.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 4","pages":"1713 - 1735"},"PeriodicalIF":1.9,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883600","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":"The Use of Gravity Gradient Tensor Eigenvectors to Recover the Basic Geometric Properties of 2D Density Boundaries","authors":"Roman Beránek,&nbsp;Jan Mrlina","doi":"10.1007/s00024-025-03667-5","DOIUrl":"10.1007/s00024-025-03667-5","url":null,"abstract":"<div><p>Many geological structures such as faults, calderas, large intrusions, etc. can be approximated by a density boundary model that can be characterised by dip, edge position, depth and density contrast. Gravity gradiometry is a geophysical method that can be used to investigate some of the properties of such geological structures. In this study, we have tested a method for estimating the slope of the density boundary based on analysing the inclination angles of the gravity gradient tensor eigenvectors above the edge of the contact. We also introduced a new edge detection technique that uses the rate of change of the eigenvectors of the gravity gradient tensor. We found that the dip angle of a density boundary cannot be derived directly from the inclinations of the eigenvectors above the contact. On the other hand, we have found that the edge position given by the maximum rate of change of the eigenvector inclinations works better than the vertical and horizontal gradient methods in case the measurements are performed at a considerable height above the boundary. This new edge detection method may therefore be suitable for aerial gravity gradiometry data interpretation.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"557 - 569"},"PeriodicalIF":1.9,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638342","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":"Imaging Mofette Structures in the Ohře Rift System, Czech Republic, Using Radio-Magnetotelluric Data","authors":"Paula Rulff,&nbsp;Ute Weckmann,&nbsp;Thomas Kalscheuer,&nbsp;Gregor Willkommen,&nbsp;Laura Maria Buntin,&nbsp;Anna Platz","doi":"10.1007/s00024-025-03665-7","DOIUrl":"10.1007/s00024-025-03665-7","url":null,"abstract":"<div><p>The pathways of fluids and mantle-originated carbon dioxide in the seismically active Ohře (Eger) Rift system appearing as mofettes at the surface are currently subject to investigation, especially by the International Continental Scientific Drilling Program “Drilling the Eger Rift”. If the aquifers show significant contrast in electrical resistivity to the host rocks, they can be investigated with geo-electromagnetic methods. However, imaging complex fluid and CO₂ pathways in detail in near-surface structures is challenging, because, in contrast to the background stratigraphy, they are often oriented in near-vertical directions. Therefore, we aim to investigate how the shallow aquifer structures can be examined best with an inductive electromagnetic method. For this purpose, we collected radio-magnetotelluric data in the Hartoušov mofette field and evaluated them by two- and three-dimensional inversions. Data from a nearby magnetotelluric station, drill hole data, gas flux measurements and electrical resistivity tomography models were used to assess the reliability and robustness of our inversion results. We concluded that the near-surface fluid reservoirs are adequately depictable, while the migration paths of gaseous CO₂ cannot be traced properly due to a lack of resistivity contrast. Our model analyses suggest that imaging the given geological setting with fluids and gases ascending in anastomosing pathways benefits from a fine-scale three-dimensional inversion approach because the fluids mostly appear as local conductive reservoir-like anomalies, which can be falsely projected onto the profiles during inversion in two dimensions. The resistivity models contribute with detailed images of the near-surface aquifers to the geodynamic model of the Ohře Rift.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"609 - 636"},"PeriodicalIF":1.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00024-025-03665-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ANN-Based Ground Motion and Physics-Based Broadband Models for Vertical Spectra","authors":"Varun Sharma,&nbsp;Harsh Kumar Arya Author,&nbsp;Maheshreddy Gade,&nbsp;J. Dhanya","doi":"10.1007/s00024-025-03660-y","DOIUrl":"10.1007/s00024-025-03660-y","url":null,"abstract":"<div><p>This study proposes a new simplified Ground Motion Model (GMM) for vertical spectra by combining comprehensive datasets from the NESS and NGA-West2 databases. The proposed Artificial Neural Network (ANN) architecture-based model requires only 288 unknowns to predict spectral accelerations (<i>Sa</i>) at 33 distinct periods ranging from 0 to 4 s. Notably, this model inherently captures known physical phenomena with reduced variability using a minimum number of unknowns compared to the GMMs existing literature, thus offering a valuable addition to current hazard estimation frameworks. Furthermore, recognizing the necessity for physics-based simulations in vertical ground motion analysis, we introduce a physics-based broadband model for vertical spectra using ANN methodology. The proposed broadband model exhibits better robustness due to the comprehensiveness of the dataset utilized and the inclusion of source path and site characteristics at the input layer. Additionally, the model effectively captures the physical trends with minimal deviation. Further, we verified the predictive ability of the developed models through a comprehensive case study of the 2008 Iwate–Miyagi earthquake. The proposed models serve as essential tools for physics-based broadband simulations and hazard assessments in active shallow crustal regions.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"637 - 665"},"PeriodicalIF":1.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638128","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":"Velocity Analysis Using High-resolution Hyperbolic Radon Transform with ({L}_{{q}_{1}}-{L}_{{q}_{2}}) Regularization","authors":"Qiuying Wu,&nbsp;Bin Hu,&nbsp;Cai Liu,&nbsp;Junming Zhang","doi":"10.1007/s00024-024-03651-5","DOIUrl":"10.1007/s00024-024-03651-5","url":null,"abstract":"<div><p>Improving the accuracy of velocity analysis is crucial to ensure the precision of subsequent data processing and interpretation. Especially for seismic data containing multiples, extracting primary velocity information requires a high-resolution velocity spectrum. We propose a high-resolution hyperbolic Radon transform velocity analysis method based on nonconvex <span>({L}_{{q}_{1}}-{L}_{{q}_{2}})</span> mixed regularization sparse inversion that can handle this problem. In this way, we improve the resolution of the velocity spectrum while eliminating the interference of multiples. To address the difficult problem of nonconvex optimization, we use an improved alternating direction method of multipliers algorithm approximation and provide the convergence condition. To study the stability of method, we analyzed the impact of <span>({q}_{1})</span> and <span>({q}_{2})</span> on the results. And we compare the proposed method with the velocity curve picked manually, the traditional and <span>({L}_{1})</span> regularization method, and the results of synthetic and actual data show the effectiveness of our proposed method.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 4","pages":"1657 - 1671"},"PeriodicalIF":1.9,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883551","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":"Study of the Spatiotemporal Variations of Rainfall Warning Risks of Conventional Non-highspeed Railways in China","authors":"Zhang Xiaomei,&nbsp;Jiang Ying,&nbsp;Chen Zhongyu,&nbsp;Zhang Hui,&nbsp;Wang Yuhong,&nbsp;Gao Jingjing,&nbsp;Wu Hao,&nbsp;Huang Weiwei,&nbsp;Qian Ya","doi":"10.1007/s00024-025-03658-6","DOIUrl":"10.1007/s00024-025-03658-6","url":null,"abstract":"<div><p>China’s complex terrain and diverse rainfall patterns contribute to uneven and distinctiverainfall distributions. Over 70% of disasters and accidents on conventional non-highspeed railways in China are influenced by rainfall. This paper analyses the spatiotemporal variations in rainfall warning risk on conventional non-highspeed railways in China. The study reveals the following findings: (1) Both the annual total rainfall and the risk hours of railway rainfall warnings exhibit east–west and south–north spatial distributions, with more rainfall in East China and South China and less rainfall in West China and North China. Southern China experiences the highest rainfall levels and the most intense rainfall, whereas the northern and northeastern regions have the highest risk hours for railway inspections. Sichuan and Yunnan have the highest occurrence rates of railway speed restrictions and closures. (2) The peak locations and periods of railway rainfall warning risk hours in various regions are closely related to the main monsoon rain belt and typhoon activities in China. Influenced by the East Asian summer monsoon, the Southeast Region experiences the earliest peak (June) in railway inspection and speed restriction rainfall warning risk hours. As the main rain belt of the monsoon moves northwards and the subtropical high extends westwards, July becomes the peak month for warning of railway rainfall risk hours in the Northeast, Central North, and Southwest Regions. In August, the impact of typhoon-induced heavy rainfall leads to a peak in railway closure rainfall warning risk hours in Southeast China. (3) In comparison, the complex terrain of the Southwest region results in a significantly higher comprehensive risk index for railway rainfall than other regions do, making it the area with the greatest railway rainfall warning pressure. The Northeast Region, with lower annual total rainfall, presents the highest frequency index for railway rainfall warning risk, implying a relatively strict preventive approach. The Southeast Region, with the highest annual total rainfall, has a comprehensive risk index second only to the Southwest Region, indicating slightly lower prevention pressure. (4) Over the past decade, the Southwest region experiences a significant increase in conventional non-highspeed railway rainfall volume, frequency, and comprehensive risk index during the main rainy season. Considering the complex terrain and frequent seismic activity in this region, it is likely to be a critical focus for future railway rainfall warning efforts.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"797 - 813"},"PeriodicalIF":1.9,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638251","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":"Comparative Analysis and Improvement of CT Scanning 3D Reconstruction Methods for Coal Samples","authors":"Xiangchun Li,&nbsp;Haonan Song,&nbsp;Yaoyu Shi,&nbsp;Xiaowei Li,&nbsp;Shuhao Zhang,&nbsp;Zichang Wang,&nbsp;Xuefei Zhuo,&nbsp;Baisheng Nie","doi":"10.1007/s00024-025-03661-x","DOIUrl":"10.1007/s00024-025-03661-x","url":null,"abstract":"<div><p>To assess the accuracy of commonly used 3D reconstruction techniques for coal samples and provide a foundation for examining the coal’s internal microstructure, as well as its mechanical and seepage properties, this study focuses on samples from the Yuwu and Yuecheng Mines. X-ray CT scanning was employed to acquire CT slices of the coal samples, which were then subjected to 3D reconstruction using Avizo, Mimics, and Matlab. By comparing and analyzing the strengths and limitations of each reconstruction method in terms of image processing quality and reconstruction fidelity, the most effective method was identified. This selected method was further refined using layer interpolation techniques, and its validity was confirmed with mercury intrusion experimental data. The results indicate that the 3D reconstructions achieved with Avizo are the most accurate and closely reflect the actual coal structure. The further improvement revealed that appropriate interpolation could bring the reconstructed coal sample data closer to the mercury intrusion data, thereby enhancing the accuracy of the coal sample’s 3D reconstruction. The improved 3D reconstruction method presented in this study provides more reliable data support for subsequent analyses of the coal’s microstructure.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"685 - 704"},"PeriodicalIF":1.9,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638252","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":"Quantification of Percentage Conversion of Incident SV-Wave Energy, Spectral Bandwidth and Dominant Frequency of Generated Rayleigh Wave in Terms of Depth and Rise-Time of Earthquake","authors":"J. P. Narayan,&nbsp; Vishal,&nbsp;Shailendra Kumar","doi":"10.1007/s00024-025-03662-w","DOIUrl":"10.1007/s00024-025-03662-w","url":null,"abstract":"<div><p>Based on the analytical and numerical solutions as well as unexpected observed damages to the buildings and long-span structures in the epicentral zone of large shallow earthquakes, structural engineers have concluded that coseismic vertical ground motion play a major role in the damages. Recent researches have revealed the generation of high frequency Rayleigh wave with large amplitude in the epicentral zone of shallow earthquakes. Further, there is meta-response of a building at its longitudinal resonance frequency as compared to flexural resonance frequency during interaction with the Rayleigh waves. This paper presents the physics behind Rayleigh wave generation in the homogeneous half-space due to an incident SV-wave at the free surface and numerical quantification of variation of dominant frequency and spectral amplitudes of the generated Rayleigh waves with focal depth, Poisson's ratio and the rise-time of the point earthquake. It is concluded that the coupling of evanescence P-wave with the critically reflected SV-wave at/just after the critical point generates Rayleigh waves. Further, generation process is not immediate just after the critical point, but, it occurs over a span at least equal to one wavelength. A relation is established between depth of point earthquake and dominant wavelength of Rayleigh wave and this relation is unaffected by the change of Poisson’s ratio, rise-time and depth of point earthquake source. There is an exponential decrease of percentage conversion of the critically incident SV-wave energy in to the Rayleigh wave energy with an increase of focal-depth. Further, this percentage conversion increases with decrease of Poisson’s ratio and an increase of rise-time of the earthquake.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"361 - 379"},"PeriodicalIF":1.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638196","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":"Dispersion Equations of Surface-Waves in a Spherical Layered Earth Through Exact Earth Flattening Transformation and Propagator Matrix","authors":"S. N. Bhattacharya","doi":"10.1007/s00024-025-03659-5","DOIUrl":"10.1007/s00024-025-03659-5","url":null,"abstract":"<div><p>Dispersion equations of Rayleigh and Love waves in a spherical layered Earth for continental and oceanic structures are derived through an ‘exact Earth flattening transformation’ (EEFT). In a spherical shell (layer), EEFT considers P- and S- velocities are proportional to radial distance (<i>r</i>) and Lamé constants are proportional to <span>({r}^{-2})</span> and obtains analytic solutions in terms of exponential functions of wave equation in spherical coordinates <span>((r,vartheta ,varphi ))</span> with origin at the centre of the Earth. Using EEFT, previous works through generalised reflection-transmission method generated dispersion equations in complex terms which create difficulties in computation; while here, with solutions from EEFT, we obtain a propagator matrix which is used to derive the dispersion equations in real terms increasing computational efficiency. The derived dispersion equations make the computation of phase and group velocities of surface-waves for a spherical layered Earth nearly as simple as that for a flat (plane) layered Earth through propagator matrix. The computational algorithm uses reduced delta (compound) matrix to evade loss of precision and layer reduction procedure to avoid overflow. To simplify computation further, we propose an ‘approximate Earth flattening transformation’ (AEFT) to compute approximate surface wave velocities in a spherical Earth. Surface-wave velocities computed through EEFT for a few Earth models are compared with the corresponding velocities through AEFT and we note that the error of approximate velocities by AEFT is within 0.1% up to significant periods of surface waves.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"527 - 536"},"PeriodicalIF":1.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638197","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":"Extraction of Dispersion and Attenuation Curves for Rayleigh Waves using Matrix-Pencil Method","authors":"Lei Pan,&nbsp;Shichuan Yuan,&nbsp;Jiannan Wang,&nbsp;Xiaofei Chen","doi":"10.1007/s00024-024-03639-1","DOIUrl":"10.1007/s00024-024-03639-1","url":null,"abstract":"<div><p>Phase velocities of surface waves can be used to estimate near-surface S-wave velocity (<span>(V_s)</span>), while attenuation coefficients of surface waves are used to characterize quality factor (<span>(Q_s)</span>). Studies show that simultaneous inversion with higher modes and the fundamental mode can increase model resolution and investigation depth. However, the existence of higher modes in surface waves introduces errors in estimated surface-wave attenuation coefficients, reducing the accuracy of estimated <span>(Q_s)</span>. To address this issue, we propose a novel technique to generate both dispersion and attenuation curves using the matrix-pencil (MP) method. We first introduce the MP method and the procedure for extracting dispersion and attenuation curves and inverting <span>(V_s)</span> and <span>(Q_s)</span>. We present two synthetic cases and one real-world case demonstrating the effectiveness of the proposed method in generating distinguished dispersion curves for the fundamental mode as well as higher modes. Essentially, the MP method successfully separates and constructs an attenuation-coefficient image for each mode. Even with a relatively small number of receivers, the approach nevertheless produces remarkably accurate images. The enhanced measurements provide a cleaner, higher-resolution dispersion and attenuation images which will aid further inversion of S-wave velocities and quality factors.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"381 - 403"},"PeriodicalIF":1.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00024-024-03639-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}