Acta Geodaetica et Geophysica最新文献

{"title":"Gradient resistivity trends modeling of the Quaternary aquifer and its overlaying and underlying layers in the semi-arid Khanasser valley region, northern Syria","authors":"Jamal Asfahani","doi":"10.1007/s40328-025-00464-3","DOIUrl":"10.1007/s40328-025-00464-3","url":null,"abstract":"<div><p>Vertical electrical sounding (<i>VES</i>) technique is applied in this paper to assess and follow the trends of layered gradient resistivity (<i>GR</i>) variations and aquifer vulnerability to contamination in the Khanasser Valley region, Northern Syria. GR parameter, termed also as longitudinal resistance (<i>LR</i>), having the Ohm unit (Ω) is therefore developed in this paper. <i>GR</i> is by definition the inverse of longitudinal conductance (<i>LC</i>) (one of the second order Dar-Zarrouk geo-electric indices). A model composed of three hydrological layers is used to test and characterize the <i>GR</i> parameter, which are the Quaternary aquifer and its overlaying and underlying layers. Thirty four <i>VES</i> points already carried out in the study area with Schlumberger array, and a maximum half current spacing <i>AB/2</i> of 500 m are used in this research. The one dimensional (<i>1D)</i> quantitative interpretations of those <i>VES</i> show that the first overlaying layer resistivity and thickness ranges are of 0.6–212 <i>Ω.m</i> with an average value of 56 <i>Ω.m</i>, and 1.1–28 m with an average value of 4.64 m respectively. The second Quaternary aquifer layer resistivity and thickness ranges are of 4.3–43 <i>Ω.m</i> with an average value of 15 <i>Ω.m</i>, and 4.5–59.2 m with an average value of 27.5 m respectively. The third underlying layer resistivity and thickness ranges are of 1.7–79.5 <i>Ω.m</i> with an average value of 11.77 <i>Ω.m</i>, and 14.3–283 m with an average value of 82.1 m respectively.<i> The (GR</i>) parameter shows also that the three modeled hydrological units are averagely vulnerable to contaminations.</p><p>Two resistivity reflection coefficients <i>K1</i> and <i>K2 are also developed and used to follow</i> the resistivity distribution trends of the three mentioned modeled hydrological units, where an alternating sequence of clay, alluvial and sandy components of ramel aswad, and marly clay is decided. <i>GR</i> parameter can be therefore employed worldwide to follow the electrical resistivity variations with depth, for several useful applications, such as assessing aquifer vulnerability to contamination, mapping the geologic sequence with depth for evaluating the subsurface for mineral explorations and for locating the engineering sites.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"71 - 96"},"PeriodicalIF":1.4,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879651","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":"Ring current local time dependence during geomagnetic storms using equatorial Dst-proxies","authors":"Santiago Pinzon-Cortes,&nbsp;Natalia Gómez-Pérez,&nbsp;Santiago Vargas Domínguez","doi":"10.1007/s40328-024-00459-6","DOIUrl":"10.1007/s40328-024-00459-6","url":null,"abstract":"<div><p>In this paper, we calculate Local Disturbance indices (LDi) using data from two equatorial observatories (Ascension ASC and Fúquene FUQ) to use them as Disturbance Storm-time (Dst) index proxies. We find that the LDi response to geomagnetic storms is different depending on the observatory’s local time at the storm onset. In order to explore this local time influence on the measurements on the ground at low latitudes, we build new proxies using two observatories located at approximately the same longitude, in order to balance measurements in the north and south averaging meridional and measuring only zonal variations. The average of the longitude pairs and Dst-index proxies from single observatories exhibit strong correlation to the Dst index (<span>(ge )</span> 0.88) during active periods and a moderate correlation (<span>(le )</span> 0.5) during quiet periods. We find that the storm intensity is associated with local time. We confirm that the fastest variation in the geomagnetic field during the storm is recorded between dusk and midnight, while the region between dawn and noon records more moderate variations, sometimes missing the storm effects altogether. Our results show an azimuthal asymmetry of the magnetospheric ring current, becoming most intense on the night side of the dusk terminator during active periods. We propose a new configuration for local time Dst proxies including the use of equatorial observatories. This will get insights of the evolution of storms in an area where there are limited geomagnetic observatories.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"97 - 114"},"PeriodicalIF":1.4,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00459-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879709","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":"Geophysical characterization for dolerite dykes (dimension stone) reserves exploration using electrical resistivity tomography (ERT) in Shergarh Oghi, Mansehra, Pakistan","authors":"Irfan Raza,&nbsp;Hashmat Ullah,&nbsp;Perveiz Khalid,&nbsp;Muhammad Zeerak Iqbal,&nbsp;Sania Rasheed,&nbsp;Muhammad Irfan Ehsan","doi":"10.1007/s40328-025-00465-2","DOIUrl":"10.1007/s40328-025-00465-2","url":null,"abstract":"<div><p>Due to rapid increase in demand of building stones the geophysical prospecting of potential dimension stone (Dolerite Dykes, commonly known as “Black Granite”) deposits is of great significant. Dimension stone is widely distributed in the Hazara Valley of KPK, Pakistan. The primary aim is to characterize subsurface structural features and resistivity values crucial for dimension stone deposits, guiding the selection of viable mining zones. Employing electrical resistivity tomography (ERT), an electric current was introduced through electrodes embedded in the ground, demonstrating efficiency, cost-effectiveness, and data coverage. Conducted with the SuperSting R8/IP/SP instrument from AGI USA, the survey utilized a dipole-dipole array with 56 electrodes spaced at 20-meter intervals along eleven profiles. The 2D-ERT technique, or resistivity imaging, employed EarthImager software from AGI USA for data inversion, revealing distinctive low and high resistivity signatures along all profiles. Shallow high resistivity values indicated boulder material, while shallow low resistivity values pointed to subsurface dolerite dyke material. Profiles exhibited deep high resistivity values, suggesting subsurface granitic soft bedrock. EarthImager™ 3D software enabled inferred resource estimations, identifying a volume of 4,349,744 cubic meters and a total tonnage of 13.04 million tons for dolerite (dimension stone) material. The 3D-ERT inversion results further enhanced the understanding of the spatial distribution of the dolerite deposits, providing high-resolution images of subsurface resistivity, which facilitated the identification of economically significant zones. Based on geophysical study it is recommended to drill six confirmatory boreholes of a minimum 150 m depth to assess and confirm dolerite dyke zones/anomalies for future mine planning in the study area.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"53 - 69"},"PeriodicalIF":1.4,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879706","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":"Response of low-latitude lower ionosphere during solar flare events over the complete solar cycle 24","authors":"Gaurish Tripathi,&nbsp;Ashutosh K. Singh,&nbsp;Prashant Singh,&nbsp;Abhay Kumar Singh","doi":"10.1007/s40328-025-00461-6","DOIUrl":"10.1007/s40328-025-00461-6","url":null,"abstract":"<div><p>The lower ionosphere of Earth is greatly impacted by solar flares. During a solar flare event, a sudden enhancement in X-ray flux leads to additional ionization, which increases electron density in the lower ionosphere. In this paper, we first investigated time the behaviour of lower ionosphere during solar flare events (SFE) over the complete solar cycle 24 during the years 2011 to 2018 by using amplitude measurement of very low frequency (VLF) waves and GOES 0.1–0.8 nm X-ray flux. The fixed frequency (19.8 kHz) VLF wave transmitted from the NWC-transmitter, Australia is observed at our low-latitude station Varanasi (geom. lat. 14^o 55^/ N, geom. long. 154^o E), India. The amplitude enhancements associated with solar flares are characterised by the two traditional Wait parameters, virtual reflection height (H^/ in km) and the sharpness factor (<i>β</i> in km^− 1) i.e. electron density gradient. These empirically determined values of H^/ and β were employed in Long Wave Propagation Capability (LWPC) to predict VLF amplitude perturbations induced by the solar flare throughout a wider frequency range than was observable. It is found that the sharpness factor increases with the increasing strength of solar flares, but the virtual reflection height decreases. These observations show a decrease in H^/ from 78 km to 62 km and an increase in <i>β</i> from 0.34 km^− 1 up to a ‘saturation’ level of 0.51 km^− 1. A comparative study of these parameters during different phases of the solar cycle shows that during the rising phase of the solar cycle, <i>β</i> is found to be lower. In contrast, during the declining phase, its value is higher. Also, H^/ decreases more during the decreasing phase of the cycle than during the rising phase. During the peak of the solar cycle, H^/ and β values are found to lie between rising and decreasing phase values, although more dispersed. This indicates that the lower ionosphere behaves differently during different phases of the solar cycle.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"115 - 136"},"PeriodicalIF":1.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879655","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":"Combined effects of terrain corrections and deterministic modifiers on the Stokes-Helmert geoid over sophisticated topography","authors":"Ramazan Alpay Abbak,&nbsp;Ropesh Goyal,&nbsp;Aydin Ustun,&nbsp;Sevda Olgun","doi":"10.1007/s40328-025-00460-7","DOIUrl":"10.1007/s40328-025-00460-7","url":null,"abstract":"<div><p>This study focuses on analysing the impact of deterministic modifications of the Stokes kernel and terrain correction methods for precise geoid determination using the Stokes-Helmert method over a sophisticated topography. Three deterministic modification methods of Stokes’s kernel (Wong-Gore, Vaníček-Kleusberg, and Featherstone-Evans-Olliver) are tried to minimize the truncation error emanating from the non-availability of gravity data all over the Earth by utilizing two independent satellite only global geopotential models. In parallel to the modified Stokes kernel functions, two terrain correction techniques, i.e., spatial-spectral combined method with mass-prisms and spatial method with mass-cylinders, have also been examined to assess their combined effects on geoid heights over the Konya Closed Basin in Türkiye. The developed geoid models are validated with GNSS-levelling data and inter-compared pixel-wise. The numerical results show that although the overall statistical values depict consistent precision for various combinations of TCs, Stokes kernel modifiers, and GGMs, a holistic validation-comparison analysis reveals significant variations in view of the cm-precise geoid.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"29 - 51"},"PeriodicalIF":1.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879708","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":"Predictive diagnosis of El Niño based on empirical sea level anomaly forecasts","authors":"Małgorzata Świerczyńska-Chlaściak,&nbsp;Tomasz Niedzielski,&nbsp;Bartłomiej Miziński","doi":"10.1007/s40328-024-00457-8","DOIUrl":"10.1007/s40328-024-00457-8","url":null,"abstract":"<div><p>The aim of this paper is to present the skills of two statistical models in anticipating the development of El Niño based on sea level anomaly (SLA) forecasts with lead time up to 12 weeks. The models are: (1) the polynomial-harmonic model (PH) combined with the threshold autoregressive model (TAR), known as the PH+TAR, and (2) PH integrated with the multivariate autoregressive model (MAR), referred to as PH+MAR. Five powerful El Niño events are considered: 1997/1998, 2002/2003, 2006/2007, 2009/2010, 2015/2016. The performance of the prediction models is calculated in specific locations in the equatorial Pacific, i.e. centres of Niño 1+2, Niño 3, Niño 3.4 and Niño 4 regions. It is found that the SLA predictions hitting the El Niño peaks reveal different accuracy for dissimilar El Niño events, with the most skillful prognoses for El Niño 1997/1998. Two specific regions are identified in which the model performance fulfils the assumed accuracy limit of 5 cm, namely the Niño 1+2 and Niño 4 regions. In addition, the PH+MAR model performed better than the PH+TAR solution.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"15 - 27"},"PeriodicalIF":1.4,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00457-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879574","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":"Structural based joint inversion of magnetometry and DC resistivity data through cross gradient constraint","authors":"Ali Dehghan Mongabadi,&nbsp;Ahmad Zarean Shirvanehdeh,&nbsp;Aynur Nasseri,&nbsp;Rashed Pourmirzaee","doi":"10.1007/s40328-024-00456-9","DOIUrl":"10.1007/s40328-024-00456-9","url":null,"abstract":"<div><p>When separate inversion of geophysical data set cannot result in desirable reconstruction of subsurface anomalies, joint inversion of geophysical methods is one of the most common ways to overcome the problem. Cross gradient based joint inversion is the only technique allowing to execute joint inversion of magnetometry and DC resistivity data. In this paper, joint inversion of magnetometry and DC resistivity, based on nonlinear equations, is carried out. Smoothness and product of depth weighting and compactness are manipulated as model weighting functions for DC resistivity and magnetometry methods, respectively. The joint inversion is first applied to noise-free synthetic data of a thin dyke to evaluate its productivity which shows that separate inversion of DC resistivity leads to poor reconstruction of the thin dyke, while magnetometry recovers the dyke model very well. After the joint procedure, the magnetic method plays the role of an efficient constraint through cross gradient to improve the resistivity model about satisfactory recovery of the thin dyke. Then, usefulness of the joint inverse algorithm is tested in the presence of the noise demonstrating its productivity for noise levels up to 5%. Ultimately, the joint inversion algorithm is utilized for the real data collected over a relatively thin dyke in Morgenzon Farm in South Africa successfully.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"1 - 14"},"PeriodicalIF":1.4,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879502","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":"Multi-instrument analysis of F-region ionospheric irregularities suppression over South America during the November 3, 2021, geomagnetic storm","authors":"Gilda de Lourdes González","doi":"10.1007/s40328-024-00458-7","DOIUrl":"10.1007/s40328-024-00458-7","url":null,"abstract":"<div><p>Equatorial ionospheric irregularities have the potential to disrupt radio communications and satellite-based navigation. The influence of geomagnetic storms on these disturbances remains not fully understood, particularly in how they may initiate or inhibit the irregularities (also called Equatorial Plasma Bubbles, EPBs). Enhanced predictive capabilities require comprehensive studies of the ionosphere’s behavior, especially within the equatorial ionization anomaly (EIA) zone, where such irregularities are more pronounced. This study examines the effect of the November 3, 2021, geomagnetic storm on equatorial ionospheric irregularities in the F region over South America. We used data from multiple instruments, including GPS, GOLD, ICON, ionosondes, SuperDARN, and AMPERE, to analyze the role of the storm-time electric fields in the day-to-day dynamics of EPBs. We found that irregularities were suppressed during the storm’s main and recovery phases. Our results suggest that the inhibition of ionospheric irregularities in the F region may be associated with a combination of westward under-shielding penetration electric field and disturbance dynamo electric fields. The present study may contribute to advancing our understanding of the ionospheric response to geomagnetic storms and to develop better predictive models for space weather impacts.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"60 1","pages":"137 - 161"},"PeriodicalIF":1.4,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879578","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":"Planning, emphasis and proposal for implementation of gravimetric control network in Israel","authors":"Gilad Even-Tzur,&nbsp;Alaa Ghanayim","doi":"10.1007/s40328-024-00455-w","DOIUrl":"10.1007/s40328-024-00455-w","url":null,"abstract":"<div><p>This study outlines the planning, emphases, and proposed implementation of a gravimetric control network for Israel. The establishment of a comprehensive and accurate gravimetric control network is crucial for various geodetic applications, including geoid determination, gravity field modelling, vertical datum establishment, and geophysical studies. This study aims to provide a framework for the development and implementation of such a network in Israel. The proposed network is divided into two orders. The first order, also known as the absolute order or zero order, comprises four stations situated in geologically stable and tranquil locations. The second order, referred to as the first order, is established through relative gravimetric measurements. This order will encompass 29 stations positioned in areas that are both stable and secure. The zero and first order stations will be evenly distributed throughout the country to ensure homogeneous coverage. The proposed gravimetric network is in conjunction with the requirements to improve the geoid undulation model of Israel. Through the establishment of a small gravimetric network and the implementation of relative gravimetric measurements, we were able to determine the optimal control point density and establish a well-structured methodology for measurement, analysis, and the adjustment process.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"59 4","pages":"367 - 379"},"PeriodicalIF":1.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00455-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142811224","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":"Selection of a calibration system for relative gravimeters and testing of the processing using the example of the Zhetygen calibration baseline in Kazakhstan","authors":"Roman Sermiagin,&nbsp;Nurgan Kemerbayev,&nbsp;Khaini-Kamal Kassymkanova,&nbsp;Guzyaliya Mussina,&nbsp;Maral Shkiyeva,&nbsp;Nikolay Kosarev,&nbsp;Kanat Samarkhanov,&nbsp;Assel Batalova,&nbsp;Azamat Rakhimzhanov,&nbsp;Yeraly Kalen","doi":"10.1007/s40328-024-00454-x","DOIUrl":"10.1007/s40328-024-00454-x","url":null,"abstract":"<div><p>This article consolidates and organizes modern methods for calibrating relative gravimeters, aiming to streamline the selection and implementation of effective calibration systems, particularly in Kazakhstan. The concept of the calibration function and various methods for its determination are presented. Practical implementations of laboratory methods relevant to modern high-precision relative gravimeters are discussed, including the tilt, moving mass, artificial acceleration, and line calibration methods. Data processing through least squares adjustment at the calibration line and an overview of existing software packages for gravity observation equalization are explored. The article also covers existing horizontal and vertical calibration systems in different countries, detailing their main characteristics and schematics. Finally, an estimation of scale factors for five years of measurements with Scintrex CG-5 gravimeters at the Zhetygen calibration line in Kazakhstan is provided.</p></div>","PeriodicalId":48965,"journal":{"name":"Acta Geodaetica et Geophysica","volume":"59 4","pages":"381 - 404"},"PeriodicalIF":1.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40328-024-00454-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258139","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}