Studia Geophysica et Geodaetica最新文献_第5页

Velocity structure and its relation to the seismicity of Datong Window and adjacent regions in Shanxi Province, North China 山西大同窗及邻区速度结构及其与地震活动性的关系

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-12-12 DOI: 10.1007/s11200-021-1026-4

Xia Wang, Meiqing Song, Na Zhang, Jinchao Shen

{"title":"Velocity structure and its relation to the seismicity of Datong Window and adjacent regions in Shanxi Province, North China","authors":"Xia Wang, Meiqing Song, Na Zhang, Jinchao Shen","doi":"10.1007/s11200-021-1026-4","DOIUrl":"10.1007/s11200-021-1026-4","url":null,"abstract":"<div><p>Datong Window is at the junction of Datong Basin and Liulengshan Range in the northern part of Shanxi Graben, China. It is important to analyze the relationship between the frequency of small earthquakes and the deep velocity structure in this region since the earthquake swarm in 1989 with the maximum surface-wave magnitude M<sub>s</sub> of 5.9. A high-resolution 3D P-wave velocity model of the crust in this region was obtained with double-difference tomography using seismic data from July 2009 to June 2019. The results show that the Datong-Yanggao seismic sequence occurred, in general, within the NE rupture zone of the earthquake swarm of 1989. The sequences from 1991, 1999, and 2010 were in the rupture zone of 1989. A series of earthquakes developed in this region, which is at the intersection of multiple faults and a low-velocity anomaly of the intermediate-lower crust. A gap of length of about 3 km was found at the southwest end of the NE Dawangcun Fault (near Lujialing). Several moderate earthquake ruptures failed to break through it. It was speculated that it may be a potential asperity. There is a possibility of an earthquake with magnitude about 5 from the gap. The relocation results for the earthquakes show that intensive small-earthquake events in Datong Window corresponding to moderate-to-strong earthquakes in Shanxi Graben were highly clustered horizontally and distributed vertically in a column. In contrast, when there was no moderate earthquake in Shanxi Graben after intensive small-earthquake events, the spatial distribution of these events in Datong Window was scattered and dispersive.</p></div>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 3-4","pages":"305 - 322"},"PeriodicalIF":0.9,"publicationDate":"2021-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4486303","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}

引用次数: 0

Two S-wave eigenvectors of the Christoffel matrix need not exist in anisotropic viscoelastic media 在各向异性粘弹性介质中，克里斯托费尔矩阵的两个s波特征向量不需要存在

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-11-15 DOI: 10.1007/s11200-021-0824-z

Luděk Klimeš

引用次数: 1

Sensitivity Gaussian packets 高斯包

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-11-15 DOI: 10.1007/s11200-021-0931-x

Luděk Klimeš

{"title":"Sensitivity Gaussian packets","authors":"Luděk Klimeš","doi":"10.1007/s11200-021-0931-x","DOIUrl":"10.1007/s11200-021-0931-x","url":null,"abstract":"<div><p>Perturbations of elastic moduli and density can be decomposed into Gabor functions. The wave field scattered by the perturbations is then composed of waves scattered by the individual Gabor functions. The scattered waves can be estimated using the first-order Born approximation with the paraxial ray approximation. For a particular source generating a short-duration broad-band incident wave field with a smooth frequency spectrum, each Gabor function generates at most a few scattered sensitivity Gaussian packets propagating in determined directions. Each of these scattered Gaussian packets is sensitive to just a single linear combination of the perturbations of elastic moduli and density corresponding to the Gabor function. This information about the Gabor function is lost if the scattered sensitivity Gaussian packet does not fall into the aperture covered by the receivers and into the recording frequency band. We illustrate this loss of information using the difference between the 2-D Marmousi model and the corresponding smooth velocity model. We decompose the difference into Gabor functions. For each of the 240 point shots, we consider 96 receivers. For each shot and each Gabor function, we trace the central ray of each sensitivity Gaussian packet. If a sensitivity Gaussian packet arrives to the receiver array within the recording time interval and frequency band, the recorded wave field contains information on the corresponding Gabor function. We then decompose the difference into the part influencing some recorded seismograms, and the part on which we recorded no information and which thus cannot be recovered from the reflection experiment.</p></div>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 3-4","pages":"296 - 304"},"PeriodicalIF":0.9,"publicationDate":"2021-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4628322","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}

引用次数: 2

Error bounds for the spectral approximation of the potential of a homogeneous almost spherical body 均匀几乎球形物体势的谱近似的误差界

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-09-04 DOI: 10.1007/s11200-021-0730-4

Blažej Bucha, Lorenzo Rossi, Fernando Sansò

{"title":"Error bounds for the spectral approximation of the potential of a homogeneous almost spherical body","authors":"Blažej Bucha, Lorenzo Rossi, Fernando Sansò","doi":"10.1007/s11200-021-0730-4","DOIUrl":"10.1007/s11200-021-0730-4","url":null,"abstract":"<div><p>Several kinds of approximation of the gravitational potential of a homogeneous body by truncated spherical harmonics series are in use in physical geodesy. However, only one of them is capable of a representation converging to the true potential in the whole layer between the Brillouin sphere and the Bjerhammar sphere of the body. We aim at providing various majorizations, namely upper bounds, of the error with the double purpose of proving explicitly the convergence in the sense of different norms and of giving computable bounds, that might be used in numerical studies. The first aim is reached for all the norms. For the second, however, it turns out that among the bounds, when applied to the example of the terrain correction of the Earth, only those referring to the mean absolute error and the mean squared error at the level of Brillouin sphere of minimum radius give significant and useful results. In order to make the computation an easy exercise, a simple approximate formula has been developed requiring only the use of the distribution function of the heights of the surface of the body with respect to the Bjerhammar sphere.</p></div>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 3-4","pages":"235 - 260"},"PeriodicalIF":0.9,"publicationDate":"2021-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11200-021-0730-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4190190","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}

引用次数: 0

The stability criterion for downward continuation of surface gravity data with various spatial resolutions over Ireland 爱尔兰不同空间分辨率地表重力资料向下延拓的稳定性判据

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-09-04 DOI: 10.1007/s11200-020-0769-7

Sajjad Sajjadi, Zdeněk Martinec, Patrick Prendergast, Jan Hagedoorn, Libor Šachl

{"title":"The stability criterion for downward continuation of surface gravity data with various spatial resolutions over Ireland","authors":"Sajjad Sajjadi, Zdeněk Martinec, Patrick Prendergast, Jan Hagedoorn, Libor Šachl","doi":"10.1007/s11200-020-0769-7","DOIUrl":"10.1007/s11200-020-0769-7","url":null,"abstract":"<div><p>The differences between local and reference geopotential values are the fundamental quantities of interest in the geodetic boundary value problem approach for connecting independent height reference frames. The local gravity potential values are usually derived from gravimetric and geometric geoid undulations. In determining the short-wavelength components of the gravimetric geoid, a harmonic or analytical downward continuation of the external harmonic functions of gravity to the geoid is necessary. This study analyses the stability of the Poisson downward continuation technique with respect to varying the spatial resolution of surface gravity data in Ireland in order to estimate an effective grid resolution on this reduction. Results of the study show that the minimum range of 500-m resolution provides an unconditionally stable solution to downward continuation without the need for regularisation of the computation algorithm. In this case, downward continued data contribute from −13 to 12 mm to geoid heights and from −0.128 to 0.118 m<sup>2</sup>s<sup>−2</sup> to local gravity potential value at Malin-Head tide gauge station in Ireland.</p></div>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 3-4","pages":"219 - 234"},"PeriodicalIF":0.9,"publicationDate":"2021-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4194234","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}

引用次数: 1

Erratum to “Bounds and averages of seismic quality factor Q” “地震质量因子Q的界限和平均值”的勘误

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-07-28 DOI: 10.1007/s11200-021-0428-7

Ayman N. Qadrouh, José M. Carcione, Mamdoh Alajmi, Jing Ba

引用次数: 0

Relationship between soil magnetic susceptibility enhancement and precipitation in Cretaceous paleosols 白垩纪古土壤磁化率增强与降水的关系

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-07-28 DOI: 10.1007/s11200-020-0576-1

Xiaojing Liu, Jiasheng Chen, Qin Xie

{"title":"Relationship between soil magnetic susceptibility enhancement and precipitation in Cretaceous paleosols","authors":"Xiaojing Liu, Jiasheng Chen, Qin Xie","doi":"10.1007/s11200-020-0576-1","DOIUrl":"10.1007/s11200-020-0576-1","url":null,"abstract":"<div><p>Magnetic susceptibility (MS) is widely used for paleoclimate reconstruction. In one of the previous studies, data from 12 locations of modern middle- and low-latitude soils revealed that MS increases with increasing precipitation from approximately 200 to 1000–1200 mm yr<sup>−1</sup> and then decreases with further precipitation. However, as a result of diverse sediment sources from different locations, the MS value can deviate, affecting its relationship with the climate. Sediments of a section experience dry-wet contrast due to the migration of climate zones as a function of geological time, and form different soil types with various colors. If the sediments of a section have the same source material, different soil types in that section would enable us to explore the relationship between MS enhancement and precipitation using paleosols and to verify the previous results. Herein, we investigated Cretaceous variegated sediments in the Zhonggou and Xiagou Formations located in the Hexi Corridor of China. The rare earth and trace element analyses reveal that these sediments have the same source area. Environmental magnetism and geochemical methods reveal that the sedimentary environment of the yellowish-brown, red, and grayish-white sediments ranges from dry to wet. Precipitation reconstruction for the paleosols with a climate transfer function shows that MS increases with increasing precipitation up to approximately 800 ± 182 mm yr<sup>−1</sup> and decreases with higher precipitation amounts. The changing pattern of MS is consistent with the previous results, but the inflection point in the MS vs. precipitation curve appears at slightly lower precipitation value. Thus, paleosol sequences are suited for the analysis of paleoprecipitation trends with the help of MS.</p></div>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 3-4","pages":"323 - 340"},"PeriodicalIF":0.9,"publicationDate":"2021-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-020-0576-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5081964","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}

引用次数: 0

Two-dimensional magnetotelluric data inversion using Lanczos bidiagonalization method with active constraint balancing 利用主动约束平衡的Lanczos双对角化方法反演二维大地电磁资料

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-04-13 DOI: 10.1007/s11200-020-0150-x

Faegheh Mina Araghi, Mirsattar Meshinchi-Asl, Ali Nejati Kalateh, Mahmoud Mirzaei

{"title":"Two-dimensional magnetotelluric data inversion using Lanczos bidiagonalization method with active constraint balancing","authors":"Faegheh Mina Araghi, Mirsattar Meshinchi-Asl, Ali Nejati Kalateh, Mahmoud Mirzaei","doi":"10.1007/s11200-020-0150-x","DOIUrl":"https://doi.org/10.1007/s11200-020-0150-x","url":null,"abstract":"<p>The magnetotelluric (MT) technique is an electromagnetic geophysical method, which is widely used as a complementary to seismic surveys for exploration of hydrocarbon reservoirs. In the inversion process, the method of matrix inverse calculation has a considerable effect on the speed of the inversion and the quality of obtained models. Lanczos Bidiagonalization (LB) method has been reported to be a fast and efficient approach for solving the inversion problems. In this study, we employ LB method for inverting large-scale 2D MT data. In LB algorithm, the full set of equations is replaced by a dimensionally reduced system of equations. As a result, the speed of the solution procedure is increased, while the original problem is solved with a high accuracy. In addition, we employ active constraint balancing approach for determining the optimum regularization parameter. The advantage of the method is that for highly resolvable parameters, a small value of the Lagrangian multiplier is assigned, and vice versa. The results of the synthetic data inversion show that both methods require equal computer memory but LB method is faster and more reliable than conjugate gradient method. The proposed approach is also applied to inverse real MT data collected from the Kashan area. The Kashan area is the most interesting area for oil and gas exploration of the Central Iran Basin. The inversion results obtained by LB are in a good agreement with the geological structure of the study area and the drilling data.</p>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 2","pages":"184 - 205"},"PeriodicalIF":0.9,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-020-0150-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4518040","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}

引用次数: 0

An alternative geoid model for Africa using the shallow-layer method 非洲浅层法大地水准面模型

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-04-08 DOI: 10.1007/s11200-020-0301-0

Mostafa Ashry, Wen-Bin Shen, Hussein A. Abd-Elmotaal

{"title":"An alternative geoid model for Africa using the shallow-layer method","authors":"Mostafa Ashry, Wen-Bin Shen, Hussein A. Abd-Elmotaal","doi":"10.1007/s11200-020-0301-0","DOIUrl":"https://doi.org/10.1007/s11200-020-0301-0","url":null,"abstract":"<p>The aim of the current investigation is to determine an alternative geoid model for Africa using the shallow-layer method. The shallow-layer method, following the basic definition of the geoid, differs essentially from the traditional geoid determination techniques (Stokes and Molodensky) that it doesn’t need real gravity data. It comes from the definition of the geoid. Here, the shallow-layer method is used to determine a 5′ × 5′ geoid model for Africa covering the latitudes between ?36°N and 39°N and longitudes from ?20°E to 53°E The Earth Gravitational Model (EGM2008), the global topographic model (DTM2006.0), the global crustal model (CRUST1.0) and the Danish National Space Center data set (DNSC08) global models have been used to construct and define the shallow layer and its interior structure. A combination of prism and tesseroid modelling methods have been utilized to determine the gravitational potential produced by the shallow-layer masses. The validation and tests of the computed shallow-layer geoid have been done at two different levels. First, a comparison between the computed shallow-layer geoid and the recently developed AFRgeo2019 gravimetric geoid for Africa (based on real gravity data) has been carried out. Second, a comparison of the computed shallow-layer geoid with several geoid models computed using different global geopotential models has been performed. The results show that the computed shallow-layer geoid behaves similarly to those determined by the global geopotential models. Differences between the shallow-layer and the AFRgeo2019 gravimetric geoids are generally small (below 0.5 m) at most of the African continent</p>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 2","pages":"148 - 167"},"PeriodicalIF":0.9,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-020-0301-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4327407","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}

引用次数: 4

Comparison of three methods for computing the gravitational attraction of tesseroids at satellite altitude 计算卫星高度曲面引力的三种方法的比较

IF 0.9 4区地球科学

Studia Geophysica et Geodaetica Pub Date : 2021-03-12 DOI: 10.1007/s11200-020-0149-3

Longjun Qiu, Zhaoxi Chen

{"title":"Comparison of three methods for computing the gravitational attraction of tesseroids at satellite altitude","authors":"Longjun Qiu, Zhaoxi Chen","doi":"10.1007/s11200-020-0149-3","DOIUrl":"https://doi.org/10.1007/s11200-020-0149-3","url":null,"abstract":"<p>Global gravity modelling is one of the most important issues in geophysics and geodesy. Because a tesseroid model comprises the curvature of the Earth, the computation methods for the gravitational potential of tesseroids and its first-order derivatives in spherical coordinates are attracting great attention in recent years. In this paper we deal with the numerical evaluation of the radial component of the gravitational attraction generated by tesseroid masses at satellite height with the Gauss-Legendre quadrature (GLQ), the Taylor series expansion (TSE) and the prism approximation (PA) methods. Forward modelling of tesseroids of 1° × 1° and 5′ × 5′ are performed by three computation methods and the comparison between them are made in terms of computational efficiency and accuracy. The numerical results show that the GLQ of order 5 can provide the adequate accuracy for the gravity modelling of 1° × 1° tesseroids at satellite height. The GLQ of order 2 and TSE methods are superior to the PA approach in both computational accuracy and efficiency. The satellite height has important impact on the accuracy of the GLQ and TSE, whereas it has no effect on the PA method. In addition, we developed combined GLQ approach and combined TSE method, respectively, for global gravity modelling based on 1° × 1° and 5′ × 5′ tesseroids. Apart from the synthetic tesseroids, 1° × 1° data from the CRUST1.0 global crustal model and 5′ × 5′ rock-equivalent topographic data from the Earth2014 model are used to validate two combined methods. The numerical results show that these two combined methods can balance the computational accuracy and efficiency.</p>","PeriodicalId":22001,"journal":{"name":"Studia Geophysica et Geodaetica","volume":"65 2","pages":"128 - 147"},"PeriodicalIF":0.9,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11200-020-0149-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4504733","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}

引用次数: 3