Acta Geodaetica et Geophysica最新文献

{"title":"Geoelectric modeling of gold mineralization in a coarse topographic relief using structured and unstructured meshing","authors":"Ali Mohammadi,&nbsp;Maysam Abedi,&nbsp;MirSaleh MirMohammadi,&nbsp;Ahmad Zarean","doi":"10.1007/s40328-025-00476-z","DOIUrl":"10.1007/s40328-025-00476-z","url":null,"abstract":"<div>\u0000 \u0000 <p>Geo-electrical methods, including electrical resistivity and induced polarization, are key tools for the identification and assessment of mineral deposits, particularly gold. In this study, nine electrical profiles were surveyed in a region characterized by volcano-sedimentary outcrops and silicic dikes in northeastern Azerbaijan. The data underwent inversion modeling using two meshing approaches: structured (quadrilateral) and unstructured (triangular), allowing for an evaluation of their effects on the interpretation of subsurface electrical characteristics. The results indicated that unstructured modeling provided superior resolution and lower error compared to structured modeling in areas of rugged topography, yielding a more accurate depiction of gold-related sources. The analysis revealed a strong correlation between resistivity and induced polarization data with the presence of gold in vein-hosted mineralization and hornfels units. Furthermore, two distinct mineralization trends were identified: a shallow trend associated with sulfides in hornfels and a deeper trend linked to silicic veins, both closely aligned with gold grades and modeling patterns. In addition, the alignment of anomalies with regional fault structures and mineralizing fluid pathways confirms the area’s substantial potential for gold mineralization within low-sulfidation epithermal systems. Ultimately, the findings suggest that the combination of unstructured meshing and inversion modeling can serve as an effective tool for high-precision mineral exploration in geologically complex regions.</p>\u0000 </div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 4","pages":"395 - 423"},"PeriodicalIF":1.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145808737","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":"Surface-fitting by partitioned multiple regression equations in oblique territories and its use in coordinate transformations","authors":"Andrew Carey Ruffhead","doi":"10.1007/s40328-025-00475-0","DOIUrl":"10.1007/s40328-025-00475-0","url":null,"abstract":"<div><p>A bivariate polynomial is an important type of explicit function that can approximate a physical quantity that varies continuously and smoothly over a surface. Such functions can be derived by successive least-squares optimisations which determine which terms are statistically significant, the results being designated as multiple regression equations (MREs). One application is coordinate shifts from one geodetic positioning system (datum) to another. Recent research has found accuracy benefits from partitioned MREs in which two polynomials are joined together smoothly, reducing the need for high-power terms. Case studies from that research suggested that partitioning should be across whichever of the north–south and east–west extents was the greater. The paper investigates whether diagonal partitioning is best for data in oblique territories (where the line of greatest extent is diagonal). The case study selected was coordinate transformations in Slovenia which is relatively oblique. Oblique partitioning was not in itself an improvement on east–west partitioning but became so when contributing to two hybrid models. More research is needed but results so far suggest that the best course is to test all partitioning options and apply the one that gives the closest fit to the particular data.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 3","pages":"357 - 373"},"PeriodicalIF":1.8,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248312","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 study on the source parameters and rupture characteristics of the August 6, 2023, MS 5.5 earthquake in pingyuan, Shandong","authors":"Shaohui Zhou,&nbsp;Jian Li,&nbsp;Qijie Zhou,&nbsp;Junhao QU,&nbsp;Huilin Wang,&nbsp;Shuang Wu,&nbsp;Yu Wang,&nbsp;Yajun Li","doi":"10.1007/s40328-025-00474-1","DOIUrl":"10.1007/s40328-025-00474-1","url":null,"abstract":"<div><p>Based on earthquake data from the Shandong Seismic Network from August 6, 2023, to September 14, 2023, the source physical parameters of nine <i>M</i>_L ≥ 2.5 earthquakes in the Pingyuan seismic sequence are initially calculated based on the Brune model. Then, the earthquakes in the Pingyuan seismic sequence are located using the double-difference earthquake location algorithm (DDELA), and the focal mechanism of the mainshock is inverted via the cut-and-paste method. Finally, the source parameters of the Pingyuan earthquake and the rupture process are analyzed. The results show that the <i>M</i>_S 5.5 Pingyuan mainshock exhibited a substantial stress drop, which was notably higher than the typical global average of 4 Mpa. This was accompanied by a large source rupture radius and a significant release of energy, indicating that this seismic event occurred under high-stress environment. This may explain the great damage observed near the epicenter and the intense surface shaking. According to the DDELA results, the focal depth of the mainshock was approximately 19.9 km, and the focal depths of the aftershocks were mainly distributed in the range of 18–24 km; the focal depths were distributed in a nearly vertical banded zone, indicating a steeply dipping fault plane. The large focal depths were attributed to the thick loess cover in the Pingyuan area, which is part of the sedimentary plain of the Yellow River. Based on a comprehensive analysis of the focal mechanism solution of the <i>M</i>_S 5.5 Pingyuan earthquake and the spatial distribution of the precisely relocated hypocenters of the aftershocks, the <i>M</i>_S 5.5 Pingyuan earthquake was generated by a right-lateral strike-slip fault striking NE–SW under principal compressive stress oriented in the ENE direction. The main seismogenic structure of this earthquake was the NE-trending Lingxian–Guanxian fault, which is a right-lateral strike-slip fault with a high dip angle. Moreover, the temporal variation in the stress drop in the aftershock sequence reflects the adjustment process of the stress environment in the source area. In the early stage after the <i>M</i>_<i>S</i> 5.5 earthquake, due to the large release of stress by the <i>M</i>_<i>S</i> 5.5 mainshock, the source area overall experienced low-stress conditions for a short period, and many aftershocks occurred in this low-stress environment. Two days after the earthquake, as the stress environment in the source area gradually adjusted, the regional stress level returned to near the normal value; that is, the various blocks in the source area reached relative equilibrium. Therefore, no subsequent major seismic event occurred.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 4","pages":"375 - 393"},"PeriodicalIF":1.8,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145808736","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 dynamic variability of global positioning system (GPS) derived precipitable water vapour (PWV) over three geographical regions of Nepal","authors":"Nisarga Sharma,&nbsp;Arnav Subedi,&nbsp;Basudev Ghimire,&nbsp;Shreeram Nagarkoti,&nbsp;Balaram Khadka","doi":"10.1007/s40328-025-00471-4","DOIUrl":"10.1007/s40328-025-00471-4","url":null,"abstract":"<div><p>We study the variation of zenith total delay (ZTD) and precipitable water vapour (PWV) using global positioning system (GPS) data and observed meteorological information over three different topographical zones of Nepal: Terai, Hilly and Himalayan region. Eight GPS stations scattered across these regions were utilized for data collection. Two alternate years, 2015 and 2017 were taken as the study period and the data obtained were analysed to compare trends. Findings indicate that the average PWV levels are higher in the Terai region in comparison to the Hilly and Himalayan region, explaining the precipitation patterns over Nepal. Additionally, the daily PWV patterns show peak levels during mid-day and a decline during the night. The findings highlight the significant variability of PWV across different regions of Nepal and its implications for evaluating PWV variability across regions.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 3","pages":"299 - 312"},"PeriodicalIF":1.8,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248309","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":"Sub-regional Taylor-series modeling of the gravity potential based on von Eötvös’ torsion balance measurements","authors":"Gibárt Gilányi,&nbsp;Gábor Molnár","doi":"10.1007/s40328-025-00473-2","DOIUrl":"10.1007/s40328-025-00473-2","url":null,"abstract":"<div><p>This paper introduces a technique for modeling the gravity potential using a low-degree Taylor series expansion, specifically of three or four degrees and demonstrates its practical application. The coefficients for this gravity model are the derivatives of the gravity potential at a specified point. The coefficients are determined through Von Eötvös’ torsion balance measurements conducted on the ice sheet of Lake Balaton in Hungary, by minimizing the squares of the difference between the nearby measured (by torsion balance) and calculated second derivatives of gravity potential. The model is applicable over an area spanning several kilometers, encompassing multiple torsion balance measurements, and thus provides broader coverage compared to a strictly local model, thereby justifying its classification as a sub-regional model. The resulting gravity potential field is presented on two types of map, similarly to Eötvös’ work. The derived model characterizes the gravitational potential for the region where measurements were taken, yet it behaves unexpectedly and generates artifacts beyond this measurement area. Earlier geoid models for this region included torsion balance data; in contrast, our results provide a more detailed gravity potential model over a more confined area.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 3","pages":"335 - 356"},"PeriodicalIF":1.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-025-00473-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248311","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":"Evidence of shear and tensile fracturing in the western desert earthquakes, Egypt","authors":"Hamada Saadalla,&nbsp;Saleh Qaysi,&nbsp;Abdalla Abdelnabi","doi":"10.1007/s40328-025-00472-3","DOIUrl":"10.1007/s40328-025-00472-3","url":null,"abstract":"<div><p>In this study, a widely used moment tensor decomposition scheme and source-type plot diagrams are applied to determine the source type and mechanism of recent earthquakes in northwestern and southern Egypt. First, the full-waveform moment tensor inversion is conducted to determine the optimal faulting mechanism using an appropriate 1-D structural velocity model. Second, the complete moment tensors are decomposed into deviatoric (DEV) and isotropic (ISO) components. The earthquakes in the northwestern Dahshour region exhibit ISO components ranging from 9.2 to 38.7%, while those in the Aswan region have ISO components ranging from 2.6 to 56.4%, indicating tensile/compressive nature of fracturing. This suggests that in the Dahshour region, cracks may open or close at the source due to fluid extraction and/or injection. Similarly, earthquakes in the Aswan region are likely influenced by the charge/discharge circulation of the High Dam reservoir. Our findings suggest that in addition to natural dynamic and tectonic factors, secondary anthropogenic influences play a role in controlling seismic activity in the investigated regions. Identifying the source type and mechanism of non-double-couple earthquakes is crucial for time-dependent seismic hazard assessment, particularly in areas where large-scale fluid operations are ongoing.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 3","pages":"313 - 333"},"PeriodicalIF":1.8,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145248310","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":"Investigations into geological structure of Gulf of Saros and Gelibolu peninsula by using airborne magnetic data","authors":"Ezgi Erbek-Kıran,&nbsp;Abdullah Ateş","doi":"10.1007/s40328-025-00468-z","DOIUrl":"10.1007/s40328-025-00468-z","url":null,"abstract":"<div><p>The paper aims to investigate the geological structure of the Gulf of Saros and Gelibolu peninsula by using airborne magnetic data. To this end, derivative methods such as the second vertical derivative and tilt method have been applied to these data and created the anomaly maps. By a closer look at these maps, it is observed that there is an intense linear magnetic anomaly parallel to the shoreline of the Çanakkale Strait. This intense anomaly can be correlated with the Ganos Strike-slip Fault observed in the north-western part of the active tectonic map of Türkiye. In addition, the depth estimations utilizing the half-width method for simple geometric bodies suggest a deep source in the southwestern profile and a shallow source in the northeastern profile. As a result, it can be deduced that the magmatic material arising from the magma fills inside the strike-slip fault causing this magnetic anomaly. Such sources with deep roots could be prospective for geothermal energy as well as hydrocarbon maturation.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"163 - 178"},"PeriodicalIF":1.8,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144046","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 H-factor in regional geoid modelling: a case study with different scenarios","authors":"C. J. Nyoka,&nbsp;A. H. M. Din,&nbsp;M. F. Pa’suya,&nbsp;P. A. Odera","doi":"10.1007/s40328-025-00470-5","DOIUrl":"10.1007/s40328-025-00470-5","url":null,"abstract":"<div><p>In order to satisfy the Stokes’ solution to the Robin’s problem, the masses above the geoid are removed using an appropriate reduction scheme. This requires heights of the gravity station and at the integration or running points to be known with reasonable accuracy. The height data is used to compute the topographic, atmospheric, and downward continuation effects—essential elements of any geoid model—as well as to estimate free-air gravity anomalies. The height of the gravity station is usually tied to the local vertical network using standard heighting methods, ideally spirit levelling, while a Digital Elevation Model (DEM) is used to derive the heights at the integration points. In most developing countries, the gravity station heights are either not available or are unreliable for geoid modelling applications, since they were mostly observed to cater for the needs of geophysical exploration. By the end of the day, the geodesist has to accommodate the height information in the integral equations for computing topographical effects using the data available in the country. In this study, the different options for height information are investigated using the data available in Auvergne, central France. Geoid models are computed using different height data combinations to represent different scenarios which exist in different countries. Spherical one-dimensional (1D) Fourier transform is used to evaluate the Stokes’ integral in the framework of the Remove-Compute-Restore (RCR) technique. Results show that orthometric heights derived from a high-resolution Global Geopotential Model (GGM) with ellipsoidal heights may be as good as, if not better than, spirit-levelled heights, when used at the gravity station.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"243 - 270"},"PeriodicalIF":1.8,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145143461","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":"Symmetric similarity 3D coordinate transformation based on dual quaternion algorithm","authors":"Sebahattin Bektas","doi":"10.1007/s40328-025-00466-1","DOIUrl":"10.1007/s40328-025-00466-1","url":null,"abstract":"<div><p>Nowadays, dual quaternion algorithms are used in 3D coordinate transformation problems due to their advantages. The 3D coordinate transformation problem is one of the important problems in geodesy. This transformation problem is encountered in many application areas other than geodesy. Although there are many coordinate transformation methods (similarity, affine, projective, etc.), similarity transformation is used because of its simplicity. Asymmetric transformation is preferred over symmetric coordinate transformation because of its ease of use. In terms of error theory, the symmetric transformation should be preferred. This study discusses the topic of symmetric similarity 3D coordinate transformation based on the dual quaternion algorithm, as well as the bottlenecks encountered in solving the problem and using the solution method. A new iterative algorithm based on the dual quaternion is presented. The solution is implemented in two models: with and without constraint equations. The advantages and disadvantages of the two models compared to each other are also evaluated. Not only the transformation parameters but also the errors of the transformation parameters are determined. The detailed derivation of the formulas for estimating the symmetric similarity of 3D transformation parameters is presented step by step. Since symmetric transformation is the general form of asymmetric transformation, we can also obtain asymmetric transformation results with a simple modification of the model we developed for symmetric transformation. The proposed algorithm can perform both 2D and 3D symmetric and asymmetric similarity transformations. For the 2D transformation, replacing the z and Z coordinates in both systems with zero is sufficient.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"271 - 297"},"PeriodicalIF":1.8,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145143110","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":"Latitudinal propagation and solar wind drivers of Pc5 pulsations during the June 2015 geomagnetic storm","authors":"J. A. Lazzús,&nbsp;I. Salfate,&nbsp;M. N. Castillo,&nbsp;J. Lorca-Castillo,&nbsp;C. Olivares-Salazar,&nbsp;A. Rivera-Zepeda","doi":"10.1007/s40328-025-00469-y","DOIUrl":"10.1007/s40328-025-00469-y","url":null,"abstract":"<div><p>This study investigates the occurrence of Pc5 pulsations in the 2 to 7 mHz range at mid and low latitudes during the severe geomagnetic storm of June 21–24, 2015. This analysis employs two ground-based magnetic stations from the SAMBA network at magnetic latitudes − 16.55 and − 49.74, located in Chile and Antarctica, respectively, to explore the latitudinal distribution and drivers of Pc5 pulsations throughout the storm. Our results reveal that the intense pulsations recorded at low latitudes are synchronized with those observed at mid-latitudes and coincide with the arrival of the four interplanetary shocks associated with this event. Notably, the amplitudes of Pc5 pulsations exhibit significant latitudinal dependence, decreasing as they propagate from mid to low latitudes. Cross-correlation analyses highlight strong relationships between Pc5 amplitudes and solar wind parameters, indicating that solar wind dynamics played a critical role in the generation and propagation of these pulsations during this storm.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 2","pages":"205 - 217"},"PeriodicalIF":1.8,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144390","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}