CGG is e-only platinum (diamond) Open Access journal with single blind review published quarterly. CGG is indexed in WOS Core Collection (ESCI) and SCOPUS. CGG publishes original research papers covering a wide spectrum of earth science disciplines including structural geophysics, geodynamics, tectonics, near surface geophysics, applied and environmental geophysics, geomagnetism, gravimetry, seismology, paleo- and rock-magnetism, space weather, geodesy and geomatics, surveying engineering, hydrology, hydro-geology, atmospheric science, climatology.
Earth Science Institute of the Slovak Academy of Sciences
Subsurface structural delineation and mineralisation potential from integration of aeromagnetic and remote sensing datasets in Gabal Abu Rahaya area, South Eastern Desert, Egypt
This study investigates the subsurface geological structures and mineralisation zones in the Gabal Abu Rahaya area, South Eastern Desert, Egypt, using integrated geological, remote sensing, and aeromagnetic data. Landsat-8 imagery was processed to identify lithological contacts and fault zones, creating a refined geological map of the region. Aeromagnetic data were analysed using geophysical filters such as Reduced-to-Pole (RTP), Tilt Derivative (TDR), Centre for Exploration Targeting (CET) porphyry analysis, and Euler deconvolution to delineate subsurface structural features and mineralisation patterns. The results from both remote sensing and magnetic data showed consistent structural trends, including matching fault and contact zones, which significantly improved the reliability of structural interpretations. This data integration enhances the delineation of prospective mineralised zones, making it possible to refine geological models for the area. The approach successfully combines satellite imagery and aeromagnetic data, offering a useful methodology for mineral exploration in complex, poorly mapped regions. Ultimately, the study provides a model for targeting ore deposits in similar geologically challenging terrains, contributing to more accurate mineral exploration.
aeromagnetic, remote sensing, Egypt, South Eastern Desert, mineralisation, edge detection
Copyright (c) 2025 Sayed Omar ELKHATEEB, Ahmed M. ELDOSOUKY, Basma Mohammed HEBASHI https://creativecommons.org/licenses/by-nc-nd/4.0
A 250-year reconstruction of average July air temperatures (1775--2024): A key climate indicator of vegetation growth in the alpine treeline ecotone of the High Tatra Mts, Slovakia
The reconstruction of historical air temperatures over the past 250 years (1775–2024) in the alpine treeline ecotone (ATE) of the High Tatra Mts, Slovakia, provides insights into long-term climate variability. As a high-elevation region sensitive to climatic fluctuations, the alpine treeline is a key indicator of environmental change. A model-based approach allows estimation of air temperature where direct measurements are lacking, offering a tool for assessing long-term climate impacts in high mountains. This study models the July monthly average air temperature (JL-Tavg) and the 10°C July isotherm, a climatic threshold for vegetation growth. The regression model is based on the environmental temperature lapse rate (ETL), assuming a systematic decrease in temperature with altitude (∼0.65°C per 100 m). Using air temperature data from European stations spanning 191–3109 m a.s.l., the model estimated ETL, which was then applied to reconstruct JL-Tavg and track the 10°C isotherm across the Skalnatá dolina ATE profile. The regression model showed a good fit between observed and predicted values, with root mean square error lower than the standard deviation of average JL-Tavg. Reconstructed data indicate that the 10°C July isotherm fluctuated markedly between 1775 and 2024. The alpine treeline, defined as the elevation with zero probability of tree growth, varied from ≈ 2000 m a.s.l. during the cooler phase (1875–1974) to ≈ 2300 m a.s.l. in the warmer phase (1775–1874). Since 1975, accelerated warming has shifted this thermal boundary upward to ≈ 2400 m a.s.l., now representing the upper cold limit for alpine tree growth in the southern High Tatra Mts. Future work should integrate field monitoring, such as mapping dwarf pine above 2000 m a.s.l., to evaluate current distributional limits under ongoing warming.
cold limit, alpine treeline, average monthly air temperature, July isotherm, ETL model
Copyright (c) 2025 Svetlana VARŠOVÁ, Veronika LUKASOVÁ, Milan ONDERKA, Jiří KOPÁČEK, Dušan BILČÍK, Ján KREMPASKÝ https://creativecommons.org/licenses/by-nc-nd/4.0
Synthetic 2D GPR constant-offset radargrams: Modelling of responses of air-filled cavities with various shapes
The present study describes results from synthetic modelling of 2D GPR constant-offset radargrams (B-scans) for air-filled cavities with different shapes. The primary objective of these simulations was to enhance the understanding of actual GPR data when subsurface cavities are present. Three different numerical methods are used, based on the Finite-Difference Time Domain approach. During processing of received synthetic radargrams, migration plays a crucial role. When designing the final depth-sections, it proved to be extremely important the application of the so-called Combined Time–Depth Conversion transformation method. Final results showed with good precision the geometry and depth extent of studied cavities in the absolute majority of the calculated models. The verified processing steps sequence was also successfully applied to a real-world dataset from GPR survey data from St. Catherine's church in Banská Štiavnica.
archaeogeophysics, GPR, modelling, crypts, cavity detection
Copyright (c) 2025 Farhad HAMEKHANI, Roman PAŠTEKA https://creativecommons.org/licenses/by-nc-nd/4.0
A sign of the dayside current wedge in geomagnetic observations at Stará Ďala (present-day Hurbanovo) on 16 April 1938
The recently proposed dayside current wedge likely explains the mechanism behind the well-known Carrington geomagnetic storm on 2 September 1859, as well as an event observed in Europe on 29 October 2003. Both events were swift and intense, had unusually short recovery phases, and the most violent variation of the horizontal intensity within them occurred at mid-latitudes in the morning MLT (magnetic local time) sector. In this paper, we add the third event to the two mentioned above, a short-lasting intense mid-latitude geomagnetic field variation that occurred on 16 April 1938. We present the reconstructed magnetogram with magnetic declination recorded at Stará Ďala on 16 April 1938 and demonstrate that, at around 08:30 of MLT, the Stará Ďala Observatory was likely situated within the central part of the wedge. The time series of horizontal intensity and declination from Western Europe and North America are consistent with our hypothesis that the dayside current wedge played a role in the event of 16 April 1938.
magnetic storm, magnetic declination, field-aligned current, dayside current wedge
Copyright (c) 2025 Eduard KOČI, Fridrich VALACH https://creativecommons.org/licenses/by-nc-nd/4.0
Slope stability assessment of Ramche and Dhaibung landslides in Central Nepal using geological, geophysical, and geotechnical approaches
The Ramche and Dhaibung landslides, located along Nepal's Pasang Lhamu Highway and Jibjibe route, represent persistent slope instability hazards that threaten local infrastructure and settlements. This study integrates geomorphological, geological, geophysical, and geotechnical approaches to investigate the failure mechanisms and stability conditions of these landslides. Detailed field mapping and satellite image interpretation revealed ongoing mass movement characterized by active erosional gullies, surface deformation, and loose colluvial deposits. Subsurface investigations using Electrical Resistivity Tomography (ERT) identified key geoelectrical contrasts, with low-resistivity zones corresponding to saturated, clay-rich or fractured zones and high-resistivity zones linked to dry, coarse colluvium. These discontinuities indicate weak structural layers and potential slip surfaces at depths of 15 – 20 metres. Geotechnical tests confirmed that the slope materials comprise poorly graded, low to medium plasticity soils with low cohesion and strength. Mineralogical analysis (XRD) revealed quartz as the dominant mineral and an absence of expansive clay minerals, suggesting that slope failure is primarily driven by hydrological factors rather than swelling clays. Slope stability analysis using the Limit Equilibrium Method indicated that both landslides are stable under dry conditions but become unstable when saturated, with safety factors dropping below 1.0. Additionally, seismic loading scenarios further reduce slope stability, highlighting the compounded risk during the monsoon season. While both sites share similar geological characteristics, the Ramche landslide is more vulnerable due to deeper tension cracks and greater hydrological influence, whereas Dhaibung presents a higher risk of debris flow during rainfall due to its gully-dominated terrain. The study underscores the critical role of rainfall infiltration, weak lithology, and structural discontinuities in driving slope instability, providing a comprehensive understanding essential for landslide hazard mitigation in mountainous terrains.
Ramche landslide, Dhaibung landslide, engineering geology, Electrical Resistivity Tomography (ERT), geotechnical properties, clay mineralogy, Limit Equilibrium Method (LEM)
Copyright (c) 2025 Ashok SIGDEL, Pramod DHAKAL, Champak Babu SILWAL, Subash ACHARYA https://creativecommons.org/licenses/by-nc-nd/4.0
Application of Artificial Neural Networks for estimating index floods
This article presents an application of Artificial Neural Networks (ANNs) and multiple regression models for estimating mean annual maximum discharge (index flood) at ungauged sites. Both approaches were tested for 145 small basins in Slovakia in areas ranging from 20 to 300 km2. Using the objective clustering method, the catchments were divided into ten homogeneous pooling groups; for each pooling group, mutually independent predictors (catchment characteristics) were selected for both models. The neural network was applied as a simple multilayer perceptron with one hidden layer and with a back propagation learning algorithm. Hyperbolic tangents were used as an activation function in the hidden layer. Estimating index floods by the multiple regression models were based on deriving relationships between the index floods and catchment predictors. The efficiencies of both approaches were tested by the Nash-Sutcliffe and a correlation coefficients. The results showed the comparative applicability of both models with slightly better results for the index floods achieved using the ANNs methodology.
index flood, catchment predictors, Artificial Neural Networks (ANNs), multiple regression models
Carbonate complexes underlying Flysch belt and subsurface Neogene volcanic in the NE part of Slovakia – a potential for geothermal energy and raw materials
A positive gravity anomaly was observed in the Flysch belt realm. Based on this fact and available geological knowledge we suppose that the source of gravity anomaly might be carbonate rocks lying perhaps in the footwall of Flysch sediments. The carbonates belong perhaps to the Penninic crust cover (a part of Klippen belt), or to lower structural stage of the Flysch belt. Besides this it is interpreted more volume of Neogene subvolcanic bodies in the frame of the Flysch belt based on the results of the newest magnetic measurements in the NE part of Slovakia (Kucharič et al., in press). These are accompanied by increasing heat flow and hydrothermal alteration within neighbouring rocks what may eventuate into creation of raw materials. These two factors – carbonates and subvolcanic bodies – are important items for appraisal of new perspective in this area not only from hydrocarbon occurrences point of view (a primary intend within this area) but also for enhancement of geothermal potential of Slovak Republic and opening possibilities for prognosis of raw material occurrences as well.
applied geophysics, magnetometry, gravimetry, geothermics, carbonate complexes, Neogene volcanism, Flysch sediments, Outer Carpathians
The boundary integral method for the D.C. geoelectric problem in the 3-layered earth with a prismoid inhomogeneity in the second layer
The paper presents algorithm and numerical results for the boundary integral equations (BIE) method of the forward D.C. geoelectric problem for the three-layered earth which contains the prismoidal body with sloped faces in the second layer. This situation occurs in the sedimentary basins. Although the numerical calculations are more complicated in comparison with faces orthogonal to the x, y, z axes, the generalization to the sloped faces enables treatment of the anomalous fields for the bodies of more general shapes as rectangular prisms. The graphs with numerical results present isoline maps of the perturbing potential as well as the resistivity profiles when the source field is due to the pair of D.C. electrodes at the surface of the earth. Also presented apparent resistivity curves for the Schlumberger array AMNB sounding.
geoelectric potential field theory, boundary integral methods, double-layer potential calculation, solid angle of view, apparent resistivity for laterally inhomogeneous media
Calculation of temperature distribution and rheological properties of the lithosphere along transect I in the Western Carpathians
Using the 2D integrated modelling method, we calculated the temperature model of the lithosphere along transect I passing through theWestern Carpathians. Based on the extrapolation of failure criteria, lithology and calculated temperature distribution, we derived the rheology model of the lithosphere in the area. Our results indicate clearly that the strength decreases from the Bohemian Massif via the Western Carpathians to the Pannonian Basin. The largest strength can be observed within the upper crust on the boundary between the upper and lower crust. This phenomenon is typical for all studied tectonic units: the Bohemian Massif, the Western Carpathians and the Pannonian Basin. These results suggest mostly rigid deformation in the upper crust of the units. By contrast, the lower crust in the Bohemian Massif and the Western Carpathians reflects significantly lower strength, while in the Pannonian Basin the strength is the smallest. In all tectonic units the strength within the uppermost mantle (lower lithosphere) disappears. It can be suggested that the ductile deformation dominates in this part of the lithosphere.
integrated modelling, temperature, rheology, strength, compression, extension, the Western Carpathians
Comparative study between the structural and tectonic situation of the Southern Sinai and the Red Sea, Egypt, as deduced from magnetic, gravity and seismic data
The present study is concerned with the analysis of magnetic gravity and seismic data for the regions of the South Sinai and the Red Sea areas aiming to evaluate the subsurface geologic active structures. The magnetic method of prospecting gives an effective presentation of the subsurface structures. Moreover, the wavenumber filtering is carried out utilizing three types of filters with varying wavelengths. The application of these tools on the magnetic and gravity data discriminated the variable sources of specific depth ranges for the residual and regional anomalies, as well as those limited to a certain depth interval. Also it was found that the main tectonic trends have taken the NE–SW and NW–SE directions. A three-dimensional (3D) interpretation of the Bouguer anomaly and aeromagnetic maps of the Gulf of Suez rift and the northern part of the Red Sea rift are presented. A high-resolution 3D model constrained with the seismic results reveals a possible crustal thickness and density distribution of the north Red Sea rift between the sedimentary cover and the mantle.
geomagnetic measurements, interpretation of the gravimetric measurements, filtering, the Southern Sinai, the Red Sea
Geomagnetic variations induced by the partial solar eclipse of November 25, 2011
We examine the geomagnetic variations observed from the SAMBA network during the partial solar eclipse on November 25, 2011, in Antarctica. The eclipse reached nearly 90% obscuration in the western Antarctic Peninsula at the point of greatest eclipse at 06:21 UTC. Six magnetic ground stations distributed across Chile and Antarctica, around 0° longitude and at various latitudes, were used to collect geomagnetic field data in X, Y, and Z coordinates at a 1-second resolution. A baseline from the international Q-days of the month was applied to filter out isolated signals caused by the eclipse. Results indicated a systematic decrease in both the X and Y components, synchronized with the passage of the penumbra.
partial solar eclipse, geomagnetic field, geomagnetic fluctuations, SAMBA network, solar-terrestrial interactions, Antarctica, Chile
Copyright (c) 2025 Juan A. LAZZÚS, Ignacio SALFATE https://creativecommons.org/licenses/by-nc-nd/4.0
Integration of aquifer resistivity and hydrogeochemical data for groundwater quality assessment in a basement complex terrain of Osogbo metropolis, Southwest Nigeria
In this paper, one hundred and nine vertical electrical sounding data were acquired and quantitatively interpreted to delineate the subsurface sequence and determine the geoelectric parameters. One hundred and eighteen shallow wells with measured depths to the water table were sampled and thirty-five ground-water samples were analysed for physicochemical parameters, in a view to assessing the groundwater quality in Osogbo metropolis, Southwest Nigeria. The delineated subsurface layers included the topsoil/laterite, weathered layer; partly weathered/fractured basement and the basal fresh basement with respective resistivities and thicknesses: 13 – 4727 Ωm and 0.2 – 8.9 m; 70 – 641 Ωm and 0.8 – 32.0 m; 18 – 826 Ωm and 1.8 – 27.9; and 349 – ∞ Ωm and ∞ m. The main aquifer unit identified was the weathered layer which was classified into ≤ 100 Ωm (low), 101 – 350 Ωm (moderate) and 350 – 750 Ωm (high) resistivity zones. Depths to the water table ranged from 3.1 – 40.7 m. The analysed physicochemical parameters included the pH (5.31 – 7.33), Electrical Conductivity (EC) (90 – 1709 μs/m); Total dissolved Solid (TDS) (89 – 1227 mg/L); Ca2+ (1.9 – 93 mg/L); Na+ (9.2 – 349 mg/L); K+ (0.8 – 60 mg/L); and NO3− (0.9 – 4.9 mg/L). The central district of the study area with relatively shallow water table < 12 m) and cluster of ancient waste dumpsites fell within the low resistivity zone having physicochemical characteristics of high TDS (623 – 1227 mg/L) and EC (903 – 1709 μs/m) and elevated concentrations of Na+ (120 – 349 mg/L), Ca2+ (48 – 93 mg/L) and K+ (25 – 60 mg/L) relative to WHO (2022) and SON (2015) thresholds for potable water and adjudged a poor groundwater quality zone. The pollutant is suspected to be leachates from waste dumpsites and pit latrines.
aquifer resistivity, basement complex terrain, Osogbo metropolis, physicochemical parameters, shallow wells, water quality
Copyright (c) 2025 Oyelowo Gabriel BAYOWA, Gbenga Olakunle OGUNGBESAN, Akinola Bolaji ELUWOLE, Kehinde Francis AKINLOYE, Isaiah Oluwadara ADELERE, Hussain Olanrewaju ABUBAKAR, Segun Adebayo BABATUNDE https://creativecommons.org/licenses/by-nc-nd/4.0
Integration of radioactive, conventional logs and geochemical analyses to evaluate the hydrocarbon system of Rudeis Formation, October oil field, Gulf of Suez, Egypt
The objective of this research is to determine the source rock by using a combination of well logging data, spectral gamma-ray logs, as well as laboratory geochemical analysis. This involves quantifying the total organic carbon content (TOC) as a key parameter to study the source rock of Rudeis Formation rocks in the October oil field, Gulf of Suez, Egypt. After theoretical calculations of well logging, the mean TOC value comes out to 1.2 wt%. The TOC values in the lab ranged from 0.4 wt% to 1.4 wt%, with a mean value of 0.9 wt%. According to Rudeis Formation's petrophysical properties, the hydrocarbon saturation levels in the upper and lower Rudeis reservoirs were recorded 57% to 60%, and the percentages of shale content in each reached 63% and 51%, respectively. The Radiogenic Heat Production (RHP) values ranged from 0.85 μW/m3 (minimum) to 2.38 μW/m3 (maximum) with a mean of 1.37 μW/m3 and a standard deviation of approximately 0.19 μW/m3. Five sections along the Rudeis Formation (Source 1 to Source 5) are considered hydrocarbon-bearing zones. Three of the zones were classified as source rocks (Source 2, Source 3, and Source 5) associated with a high volume of shales (mostly clay), while the other two zones (Source 1 and Source 4) are associated with a moderate volume of shales (shaly sandstones) considered to be source and reservoir rocks in the Upper and Lower Rudeis Formation. The lower Rudeis unit appears to have fair to good hydrocarbon potential, with TOC ranging from 0.46 to 1.28 weight percent and S2 varying from 0.88 to 3.76 mg/g. The upper Rudeis member is classified as a fair oil source rock, based on TOC values ranging from 0.42 to 1.29%. The equations (1), (2) and (3) were found to be the best fit to the TOC data.
radiogenic heat production, October oil field, total organic carbon, hydrocarbon system
Copyright (c) 2025 Marwa Z. EL-SAWY, Ibrahim M. AL-ALFY, Sherif FAROUK, Tarek F. SHAZLY, Nouran S. SALAMA https://creativecommons.org/licenses/by-nc-nd/4.0
Intermodel and method comparison of mean radiant temperature from numerical weather prediction models: Evaluation of enhanced spatial resolution in Europe
Thermal stress indices play a vital role in evaluating human health risks related to heat and cold. Mean Radiant Temperature (MRT), derivable from numerical weather prediction (NWP) models, is a critical input for many such indices. This research generates high-resolution (5.5 km × 5.5 km) MRT estimates across Europe using the CERRA NWP system. We evaluate different computational approaches, benchmark the high-resolution MRT against the established ERA5-HEAT dataset, and validate results using BSRN ground observations. The study focuses on diverse European environments. Our high-resolution MRT product demonstrates comparable performance to ERA5-HEAT over flat terrain but offers substantial accuracy gains over complex terrain, including mountainous and coastal regions. These findings highlight the value of enhanced spatial resolution for accurate MRT estimation, crucial for robust thermal stress assessment and contributing to improved environmental health and safety strategies.
thermal stress, MRT, NWP, CERRA, ERA5, ERA5-HEAT, Europe, high-resolution
Copyright (c) 2025 Oleh SKRYNYK, Pavol NEJEDLÍK, Krzysztof BŁAŻEJCZYK https://creativecommons.org/licenses/by-nc-nd/4.0
An enhancement filter utilizing the modified arctangent function for the structural and tectonic interpretation of causative sources: Application to WGM2012 gravity data from the Rafsanjan Plain, Iran
Gravity data edge detection methods play a crucial role in identifying the horizontal positions of buried sources and enhancing the interpretation of subsurface structures. Among these methods, the Total Horizontal Gradient (THG) filter is widely used due to its noise stability and straightforward formulation. However, the THG filter has inherent limitations, prompting the development of refined edge detection techniques. To address these shortcomings, various approaches based on local phase analysis or normalized filters have been introduced, many of which incorporate the arctangent function to combine horizontal and vertical gradients. While these methods improve edge detection, they also exhibit drawbacks, such as the generation of spurious edges and restricted resolution. In this study, we propose the Modified Arctangent Function (MAT), which enhances gravity source edge detection by integrating the total horizontal gradient with a modified arctangent function. The effectiveness of the MAT filter is systematically evaluated against conventional filters that utilize the arctangent function and/or the total horizontal gradient. Its performance is validated through synthetic gravity data tests, both with and without noise contamination. To further assess its applicability, the MAT filter is applied to high-resolution gravity data from the WGM2012 (World Gravity Map) over the Rafsanjan Plain in Iran. Additionally, an approximated derivative calculation method is incorporated to mitigate noise amplification during the derivative computation process. The results from both synthetic and real data confirm that the MAT filter effectively detects and delineates gravity anomalies, demonstrating its potential as a valuable tool for geophysical interpretation.
edge detection, WGM2012, gravity anomaly, Rafsanjan plain (Iran)
Copyright (c) 2025 Fengjun WU, Xin-Ai XU https://creativecommons.org/licenses/by-nc-nd/4.0
Estimation of the effective elastic thickness using global gravitational, lithospheric structure, and rheology models
Geodetic satellite missions become essential tools to predict the ocean-floor relief and study the oceanic lithosphere. Satellite-altimetry measurements of the sea surface topography are converted to marine gravity values that are used to predict bathymetric depths. This procedure requires information on marine sediment deposits as well as the lithospheric elastic thickness. Moreover, the elastic thickness provides information on the lithospheric strength in the context of interpreting tectonism and geological processes. In this study, we estimated the lithospheric elastic thickness beneath the Indian Ocean and surrounding continental regions by applying two methods that determine this parameter individually for the oceanic and continental lithosphere. For the former, we used global lithospheric age and upper-mantle temperature models. For the latter, we derived this parameter using global gravitational, lithospheric structure, and rheology models. Since our estimates are based on global models, the resulting map of the elastic thickness lacks more detailed features of lithospheric strength. Nevertheless, the principal pattern in elastic thickness variations relatively closely resemble tectonic configuration and lithospheric thermal state beneath the Indian Ocean. Active divergent tectonic margins along mid-oceanic rifts are characterized by a weak lithospheric strength. The strength increases due to cooling of the oceanic lithosphere with its age, while reaching maxima ∼50 km. A relatively weak lithosphere is found beneath Madagascar (15–30 km) and Sri Lanka (24–35 km). Within the domain of the Indian Ocean, the maximum elastic thickness (∼130 km) is detected beneath continental crustal fragments of the South Kerguelen Plateau.
elastic thickness; flexure, isostasy; lithosphere; active tectonic margins, Indian Ocean
Copyright (c) 2025 Robert TENZER, Mehdi ESHAGH, Samurdhika RATHNAYAKE https://creativecommons.org/licenses/by-nc-nd/4.0
On possibilities of improving the accuracy of the geocentric gravitational constant GM by combining SLR and atomic clocks measurements
Nowadays, the geocentric gravitational constant GM is determined by solving equations of motion for trajectories of artificial satellites measured by Satellite Laser Ranging (SLR). The estimated value of GM and its uncertainty 398600441.8 ± 0.8×106 m3s−2 are currently adopted by the International Astronomical Union. In this study, we investigate possibility of improving the accuracy of GM by integrating atomic clocks measurements with SLR. The functional model defines GM in terms of geopotential differences observed by atomic clocks at two points in space and their distance measured by SLR. Two types of observation equations are established. The first equation defines geopotential differences with respect to the geoidal geopotential value W0. The second equation defines distances with respect to the geocentric position of ground-based station determined from GNSS measurements. With the improving stability of atomic clocks to 10−18, it will be possible to measure geopotential differences with the accuracy ±0.1 m2s−2 (equivalent to ±1 cm in terms of the geoidal heights), while SLR measurements can currently be carried out with sub-centimetre accuracy under optimal conditions and applying advanced corrections and numerical procedures. Taking into consideration both, accuracy characteristics and their expected improvement, we conduct sensitivity analysis to assess accuracy requirements needed to improve the accuracy GM (±0.8×106 m3s−2). Error analysis indicates that combination of relativistic measurements with SLR cannot improve the accuracy of GM due to insufficient stability of atomic clocks. Nevertheless, the accuracy improvement by an order of magnitude might be feasible if relativistic measurements are carried out by atomic clocks with stability 10−20 (or better), while also achieving sub-millimetre accuracy of SLR. Integration of relativistic measurements with SLR could improve the accuracy of GM, while the critical aspect is determination of the geoidal geopotential value W0 with sub-millimetre accuracy in terms of geoidal heights that could be achievable.
geopotential differences, relativistic geodesy, geocentric gravitational constant, atomic clocks, satellite laser ranging
Copyright (c) 2025 Robert TENZER, Pavel NOVÁK, Mehdi ESHAGH https://creativecommons.org/licenses/by-nc-nd/4.0
Estimation and mapping of Arias intensity in Nepal: Insights from seismic analysis in the Kathmandu Valley
Kathmandu Valley, the capital of Nepal, is located in the seismically active Himalayan belt and has a history of devastating earthquakes causing substantial loss of life and property damage. This study employs Probabilistic Seismic Hazard Analysis (PSHA) using the Foulser-Piggott Attenuation (FPA) model and Travasarou et al. (2003) with R-CRISIS software to calculate Arias intensity in Kathmandu Valley. Historical and recent seismic data within a 500-km radius were analysed, and the earthquake catalogue was declustered and standardized using ZMAP software, a tool developed for the statistical analysis and visualization of earthquake catalogues. Additionally, a Digital Elevation Model (DEM) based topographic analysis was conducted to assess the impact of local topography on seismic site response providing insights into, slope, soil amplification factors, and shear wave velocity across the region. The results reveal Arias intensity values ranging from 0.225 to 0.241 m/s at 2% and 10% probability of exceedance corresponding to 475 and 2475 years, mapped using ArcGIS. The analysis revealed that southwestern Kathmandu and Lalitpur exhibit higher Arias intensity values, while intensity decreases gradually from southwest to northeast. The DEM analysis further revealed that areas with low slopes, particularly in central Kathmandu, have higher soil amplification factors, potentially amplifying seismic waves. The shear wave velocity distribution highlights lower values in sedimentary deposits, indicating increased seismic vulnerability. These findings emphasize the need for effective urban planning and disaster preparedness strategies to mitigate earthquake impacts in Kathmandu Valley.
Arias intensity, PSHA, shear wave velocity, soil amplification, topographic slope
Copyright (c) 2025 Dibyashree POUDYAL, Norhaiza NORDIN, Siti Nur Aliaa ROSLAN https://creativecommons.org/licenses/by-nc-nd/4.0
Spectral gamma-ray and conventional logs to evaluate hydrocarbon potentiality in Bahareya Formation, Hayat oil field, Northwestern Desert, Egypt
Different reservoir parameters (volume of shale, total and effective porosities, water saturation and hydrocarbon saturation) of Bahareya Formation were calculated in Hayat-1 well to determine the lithology of rocks and possibility of hydrocarbon accumulation. The volume of shale percentage along the well ranges from 10 to 40%. Meanwhile the depth ranging from 2020 to 2039 m are occupied by clay deposits, in which the values reach more than 75%. Different new applications using spectral gamma-ray logs, as thorium normalization and radiogenic heat production were applied to determine hydrocarbon accumulation zones and differentiate between source and reservoir rocks. The results of radioactive techniques agree well with the results of reservoir parameters, which were calculated from conventional logs, by a percentage ratio that reach more than 80%.
spectral gamma-ray, Bahareya formation, radiogenic heat production
Copyright (c) 2025 Mohamed Ahmed SHAHEEN https://creativecommons.org/licenses/by-nc-nd/4.0
Principles of imaging subsurface magnetic susceptibility with application to synthetic and field examples
In this study, a simple new methodology for imaging subsurface magnetic susceptibility from three-dimensional (3-D) correlation tomography of magnetic data is presented. This methodology can be used to rapidly evaluate the equivalent subsurface magnetic susceptibility distribution, especially when powerful commercial programs are unavailable. In correlation tomography, the region of interest is divided into a regular 3-D grid, and the correlation is then calculated between the measured magnetic field data and the computed magnetic field data resulting from a magnetic point dipole. A probabilistic estimate of the distribution of the equivalent magnetic dipoles can be achieved using the correlation coefficient technique. The coefficient values range between −1 and +1 and are equivalent physical parameters. The cross-correlation values obtained at different depth intervals are plotted to show that the higher the correlation coefficient, the greater the equivalent magnetic dipole distribution and vice versa. The computer program was tested on both synthetic magnetic data and on real field data acquired over the west Garida and Hamama deposits in Egypt's Eastern Desert. Overall, the cross-correlation tomography approach yields quick, efficient results that can be used as a basis for subsequent in-depth modelling.
inversion, magnetic method, West Garida, Hamama, Eastern Desert, Egypt
Copyright (c) 2025 Hassan MOHAMED https://creativecommons.org/licenses/by-nc-nd/4.0
Correlation of time-different ground radiometry datasets on an example of fault survey (Hradište border fault, Turiec Basin, Western Carpathians, Slovakia)
Complex geophysical survey (seismic tomography, electrical resistivity tomography and electromagnetic interference measurement, spontaneous potential, ground penetration radar, gravimetry, magnetometry and radiometry) was carried out along 450 m-long profile crossing the assumed map track line of the Hradište border fault to specify its position and some of its features. As a result, a 115 m-wide fault zone was identified, vertically or steeply dipped to the south-east and east. Because of incompatibilities between the results of deep-range geophysical methods (seismics, geo-electrics, gravimetry and magnetometry) and the results of shallow-range radiometric methods (ground gamma-ray spectrometry and soil radon emanometry), the latter were measured twice, in 2012 and 2016 years. The comparison of results of both radiometric measurements shows an acceptable level of linear correlation mainly for thorium concentration (R = 0.87), gamma dose rate (R = 0.84), radon activity concentration (R = 0.69) and potassium concentration (R = 0.66), but very low one for uranium concentration (R = 0.12). Alongside, no correlation between soil uranium concentration and activity concentration of radon in soil air was determined. These results confirm the behaviour of measured radiometric quantities in soils and weathered rock covers, and strong influenceability mainly of uranium and radon presence in shallow subsurface horizon by changing meteorological conditions.
fault, ground gamma-ray spectrometry, soil radon emanometry, weather conditions, repeatability, correlation
Copyright (c) 2025 Andrej MOJZEŠ https://creativecommons.org/licenses/by-nc-nd/4.0
The use of space geophysics data to establish a subsurface structural frameworks map on East Uweinat ring complexes province, Southwestern Desert, Egypt
The study focuses on the east Uweinat area in the eastern sector of the Saharan continental crust and extends to the Arabian-Nubian basement rocks in the east. This area extends beyond the Egyptian territories, including the northern part of Sudan and the eastern part of Libya. The Saharan continental crust represents a challenge due to its classification as an arid to hyper arid environment and the difficulty of accessing it. The study aims to construct the regional structural framework of the basement complex that has its influence on the overlying sedimentary section, specifically in the part that belongs to the Saharan continental crust of Egypt. Space geophysical data was used, including GRACE, magnetic, SRTM Gravity Recovery and Climate Experiment, Earth Magnetic Anomaly Grid, Shuttle Radar Topographic Mission and geoid data. A qualitative and quantitative interpretation is used to highlight the subsurface geological picture and structure framework. The integration of these data helps to understand the subsurface structural framework and provide insights into the geological evolution of the region. The constructed structural framework map shows the presence of a large basin east of the Uweinat area, mainly sourced from the Nile River and a small amount of rainfall, with geological obstacles preventing water leakage out. The occurrence of the East Uweinat ring complexes and volcanism have both positive and negative impacts and must be taken into account in any systematic natural resources exploration strategy.
EMAG2, SRTM, GRACE, geoid, structural modelling
Copyright (c) 2025 Yaseen AAMER, Ashraf GHONEIMI, Salah HANAFY, Mohamed H. M. YOUSEF, Sara ZAMZAM https://creativecommons.org/licenses/by-nc-nd/4.0
Enhancing geoid modelling for accurate local geoid determination in Lagos Island: A combined GNSS and levelling approach, Eti-Osa Local Government Area, Lagos State, Nigeria
Lagos Island faces challenges from coastal hazards and inadequate infrastructure, making precise geoid modelling essential for urban planning, flood risk assessment, and infrastructure development. This study addresses discrepancies in height references and emphasizes the need for accurate geoid data to support spatial planning and disaster management. The main objective is to create a geoid model tailored to Lagos Island's unique geography and infrastructure needs. The research combines the Global Navigation Satellite System (GNSS) and levelling data which created a reliable framework for determining geoid heights with high precision across Lagos Island. The methodology uses spirit levelling to obtain orthometric heights and GNSS technology, precisely Promak2 differential GNSS Receiver, to collect positional data. Ninety stations were surveyed to ensure comprehensive area coverage. This data was used to develop a geoid model through geometrical interpolation, accurately representing the local geoid surface. In the independent test, where 10 points were excluded from interpolation, the modelled geoid heights showed an RMSE of 0.2 metres, with the largest and smallest absolute deviations being 0.4 metres and 0.01 metres, respectively. In the non-independent test, where all points were used for interpolation, the comparison between the computed (observed) and modelled geoid heights at the same points showed a mean deviation of −0.3 metres. The RMSE and standard deviation were both 0.1 metres, confirming the model's accuracy in determining the local geoid. This demonstrates its suitability for precise local geoid determination in Lagos Island, providing a valuable tool for spatial analysis, infrastructure planning, and disaster mitigation. The study highlights the importance of integrating traditional surveying techniques with modern GNSS technology to address coastal urban challenges.
GNSS, levelling, geoid modelling, orthometric heights
Copyright (c) 2024 Herbert TATA, Olamilekan Babatunde OMODEJO https://creativecommons.org/licenses/by-nc-nd/4.0
The effects of seismic activities following the 30 October 2020 Samos Island earthquakes in Izmir and its surrounding
With the increasing rate of subduction along the Hellenic Arc in the Eastern Mediterranean, the seismic activities of the Aegean plate and Western Anatolia have markedly increased over the past decade. The increase in seismic activity is quite remarkable, starting from the coasts of Çanakkale in the north of Western Anatolia, including Lesbos Island, Samos Island, Kuşadası Bay and Datca. In this context, in order to determine the current deformation after the Samos Island earthquake that occurred on October 30, 2020, measurements were performed at six continuous GNSS stations in and around Izmir. This study is jointly managed by Dokuz Eylül University, with contributions from Konya Technical University and Atatürk University, focusing on both GNSS and seismological analyses. The preliminary results of this investigation include the evaluation of seismic impacts on the continuous GNSS stations from July 1st to December 31st, 2022.
earthquake, GNSS, subduction, seismic, Izmir, Western Anatolia
Copyright (c) 2024 Oya Ankaya PAMUKÇU, Ayça ÇIRMIK, Fikret DOĞRU, Ekrem TUŞAT, Fatih UYSAL, Hasan SÖZBILIR, Ufuk AYDIN, Özkan Cevdet ÖZDAĞ, Metehan ULUĞTEKIN, Fulya ÖZDEMIR, Zülfikar ERHAN https://creativecommons.org/licenses/by-nc-nd/4.0
Application of seismic refraction tomography for determining ground water potential zone in the Qularaisi area, Sulaimaniyah city, NE Iraq
Delineating zones with the potential groundwater contains is a crucial for the effective exploration and extraction of this resource. Six seismic refraction traverses for measuring compressional wave velocities (vp) were conducted in the Qularaisi area, northwest of Sulaimaniyah City in the Kurdistan Region of Iraq to determine the ground water potential zone in the selected area, each traverse has a total length of 230 m, with an inter-geophone spacing of 5 m. The velocities and the thickness of each layer were subsequently calculated based on the obtained data. This analysis provides insights into the geological formation and composition of the area. The interpretation results reveal the presence of three distinct geological layers. The first upper layer consists of clay topsoil deposits characterized by brittle materials, with the thickness ranging from 0 to 4.2 m and seismic velocities (vp) between 339 and 583 m/s. The second layer, with a thickness of 4.2 to 16.8 m and vp values between 1248 and 2650 m/s, corresponds to recent deposits of clay, sand, silt, and gravel, interpreted as unconsolidated sediments. The third layer is characterized as a consolidated marly limestone belonging from the middle Tanjero formation, occurring at depths exceeding 20 metres. This layer reflects a more compact geological structure, distinguishing it from the overlying unconsolidated materials with the vp values ranging from 3606 to 4844 m/s. The seismic refraction results indicate that the aquifer is a sand and gravel inter-granular aquifer at the depth to the saturated groundwater layers in the area ranges from 10 to 25 m whereas lower layer of marl bed reaches to a depth of 40.2 m acts as the impermeable bed.
seismic refraction tomography, primary wave velocity, ground water, SeisIm-ager/2D
Copyright (c) 2024 Abdulla K. AMIN, Kwestan M. AHMED, Ezzadin N. BABAN https://creativecommons.org/licenses/by-nc-nd/4.0
New methods of assessing wind erosion risk: Innovative approach to soil protection respecting windbreak effect
Research and development of new soil protection methods helps to maintain sustainable soil management and prevent the degradation of valuable agricultural resources. Wind erosion is a significant environmental issue that can severely degrade landscape, impact agricultural productivity and deteriorate air quality through increased dust emissions and atmospheric pollution. The main goal of this paper was to provide a methodological protocol for mapping and assessing wind erosion risk, taking into account protective effect of both existing and intended windbreaks. Based on the Potential Wind Erosion Risk (PWE) map, which takes into account soil and climatic conditions affecting wind erosion risk, a new map of potential wind erosion risk (RPWE) was created with the inclusion of the effect of windbreaks and their protected zones on the tolerated length of plots. Using this method, it is possible to assess wind erosion risk, model the design of new wind barriers and evaluate their effectiveness. The presented method has been developed into a web application that provides all outputs online. The assessment builds on long-term studies of wind erosion potential and methods for spatial representation of land susceptibility to wind erosion. Assessment of the current state of erosion risk with existing windbreaks as well as modelling the state when some are removed or newly planted, is fundamental when building a resilient and healthy environment. The newly developed method contributes to worldwide global land degradation prevention and offers new insights into the methodological approach for assessing wind erosion.
landscape management, agricultural land, abiotic risk, soil erosion, vegetation barriers, shelterbelt, phenology
Copyright (c) 2024 Josef KUČERA, Jana PODHRÁZSKÁ, Tomáš STŘEDA, Hana STŘEDOVÁ, Petra FUKALOVÁ, Vladimír PAPAJ, Martin BLECHA, Jan SZTURC https://creativecommons.org/licenses/by-nc-nd/4.0
Preliminary estimate of current ice thickness in the Dobšiná Ice Cave by means of geophysical and geodetic methods
The presented study focuses on the Dobšiná Ice Cave, which is worldwide unique from the speleological viewpoint, belonging to the most famous caves in Europe. During the 20th century, the research of the cave was carried out within various scientific branches. In the last years, one important part of the survey is the geodetic monitoring of the ice surface by modern laser scanning methods. Since 2020, also geophysical (georadar and microgravity) research is conducted in the Dobšiná Ice Cave. In this contribution, we present preliminary results on the present ice filling thickness, based on the interpretation of vertical radargrams and 2.5D density modelling of anomalous gravity data. Maximum thickness values from georadar measurements are more than 24.5 m in the eastern part of the cave, in the lower part of the Great Hall. Roughly estimated error of the depth determination from GPR vertical sections is at the level of ±0.5 m. Results from gravimetry apparently point to the fact that the sections with largest ice thickness could be placed rather westward to the central part of the cave. This interpretation remains questionable though, still open due to missing GPR results in the central part of the cave. We hope that future additional data and 3D density modelling will help to resolve this issue.
ground penetrating radar, microgravity method, migration, topographic effect
Copyright (c) 2024 Roman PAŠTEKA, Pavol ZAHOREC, Ivan ŠULEK, Erik ANDRÁSSY, Juraj PAPČO, Katarína PUKANSKÁ, Ema NOGOVÁ, Dominika GODOVÁ, Lenka ONDRÁŠOVÁ, Jozef BÓDI https://creativecommons.org/licenses/by-nc-nd/4.0
Improving strain measurements at Tidal Station Vyhne, Central Slovakia: Technological modernization using a capacitive transducer
The year 2024 marks the 40-th anniversary of observation of Earth tides at the tidal station of Vyhne, Central Slovakia. The station was established through an international scientific collaboration in 1984. Since then, it has monitored the geodynamical phenomena almost continuously. At the beginning, the station was equipped with an extensometer with an analogue photo-recorder. Later on, the extensometer was fitted with a new sensor unit based on the principle of a capacitive transducer. The subject of this paper is the design and construction of a new sensor for measuring subtle displacements in the Earth's crust due to the action of tidal and tectonic forces. Similarly to the currently operating sensor, it is based on the simple principle of measuring voltage changes on a movable sensing electrode fastened to a quartz glass tube. However, compared to the previous analogue version, a solution using the contemporary possibilities of high computing power of a modern microcontroller as well as its integrated peripherals are employed. Measured values are stored in a flash memory in off-line mode. The device is ready for operation in on-line mode for remote data collection in real time, as well. The first recorded data indicate that the instrument is working correctly, successfully registering the tidal phenomena. However, a significantly longer measurement period is required to ensure its proper operation and to rule out any potential adverse effects. Parallel measurements are to be carried out using both the new and former sensors, and the consistency of the results shall be examined.
Earth tides, tidal deformations, extensometer, capacitive transducer
Copyright (c) 2024 Michal KUBA, Peter FABO, Jozef BÓDI, Martin BEDNÁRIK, Gyula MENTES, Ladislav BRIMICH, Jana DÉREROVÁ https://creativecommons.org/licenses/by-nc-nd/4.0
Estimation of anthropogenic noise effect on relative gravimeters using the COVID-19 pandemic period
The COVID-19 pandemic caused by the SARS-CoV-2 virus has brought many, mostly negative, effects and consequences on human lives, health, and economic issues. However, one of the very few positive side effects of lockdown measures was a less noisy and less loaded natural environment on a global scale. Many accurate geophysical instruments are negatively affected by the noise forced by all kinds of human activities, such as traffic, mining, construction, and others. In this paper, we present our attempt to estimate the influence of anthropogenic noise in the seismic band on five superconducting gravimeters and one spring gravimeter incorporated in International Geodynamics and Earth Tide Service (IGETS) using a comparison of gravity records before and during the lockdown period. For quantification of a noise, the mean power spectral density (PSD) was used. Based on this experiment we can compare and quantify how much particular IGETS stations and instruments are affected by the anthropogenic noise. For our experiment, we used Level 1 IGETS data on selected stations with a 1-second sampling rate or 1-minute time resolution where 1-second was not available. For selected stations we estimated the contribution of anthropogenic noise to the total noise in a seismic frequency band for a particular station and instrument.
superconducting gravimeters, spring gravimeters, gPhoneX, International Geodynamics and Earth Tide Service, power spectral density, anthropogenic noise
Copyright (c) 2024 Laura PÉNZEŠOVÁ, Juraj JANÁK https://creativecommons.org/licenses/by-nc-nd/4.0
Continuity of long-term climate data series after the transition from manual to automatic weather station
In climatology, transitioning from conventional manual weather stations (MWS) to automatic weather stations (AWS) presents challenges in maintaining the homogeneity of long-term data series. At the Skalnaté Pleso Observatory (1778 m a.s.l., High Tatras), manual meteorological measurements have been conducted since 1943 using the same methods and devices at the same location. In 2014, the AWS Physicus was installed to record meteorological data parallelly with manual measurements. This study processed six years of parallel measurements (2017–2022) to derive corrections for AWS monthly atmospheric precipitation totals and maximum (Tmax), minimum (Tmin) and mean air temperatures (Tmean) measured in 2023. Two correction approaches were proposed: monthly regressions (MR) and cumulative distribution functions (CDF), including Generalized Extreme Value (GEV) distribution, normal distribution (GAUSS), and Gamma distribution (GAMMA). Analyses of monthly data revealed an underestimation of precipitation totals in AWS data, with a mean bias error (MBE) of −6.8 mm and a root mean squared error (RMSE) of 20.0 mm. The most suitable correction method was the MR, which decreased MBE to 1.5 mm and RMSE to 11.1 mm. AWS monthly air temperature data were overestimated by 0.1 °C, 0.3 °C, and 0.1 °C for Tmax, Tmin, and Tmean, respectively. For Tmax, correction using the MR and GEV methods reduced the MBE to 0.0 °C and achieved RMSE of 0.1 °C for both. After applying GAUSS, MBE and RMSE decreased to 0.1 °C. The most appropriate correction method for Tmin was the MR resulting in MBE of 0.0 °C and RMSE of 0.3 °C. For Tmean, the MR and GEV methods reduced the MBE to 0.0 °C and the RMSE to 0.1 °C for both methods. These results demonstrate that AWS monthly data, when corrected using the presented methods, have the potential to maintain the continuity of historical climate data series at Skalnaté Pleso.
air temperature, precipitation, measurements, differences, correction
Copyright (c) 2024 Veronika LUKASOVÁ, Svetlana VARŠOVÁ, Milan ONDERKA, Dušan BILČÍK, Anna BUCHHOLCEROVÁ, Pavol NEJEDLÍK https://creativecommons.org/licenses/by-nc-nd/4.0