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
Geoelectrical parameter measurements using an Asymmetrical Schlumberger Sounding technique in the southern part of the Dokan area, NE-Iraq
Fifteen Asymmetrical Vertical Electrical Sounding (AVES) points were acquired along three traverses extending in the southern Dokan area. The results are quantitatively interpreted through forward and inverse modelling to calculate Dar-Zarrouk parameters include transverse resistance (RT) and longitudinal conductance (SL) calculated from true resistivity (ρ), depth (d) and thickness (h) of sequence layers succession revealing aquifers from recent sediments overlying the upper part of the rhythmic cycle of the middle Tanjero Formation. Hydraulic parameters deduced from pumping test includes aquifer transmissivity (T) and hydraulic conductivity (K) calculated from equation K = T/h. Three relationships between the Dar-Zarrouk parameters and hydraulic parameters were established. Among these, the relationship between transmissivity (T) and transverse resistance (RT) shows the highest correlation coefficient (R2 = 0.9956), indicating that it is the most precise and reliable relationship. The derived equation (T = −0.0006 RT + 23.227) can therefore be used to estimate transmissivity directly from transverse resistance values for the studied area, as well as for nearby areas with similar geological conditions, where recent alluvial sediments overlie the Middle Tanjero Formation.
Dar Zarrouk parameters; Transmissivity; Hydraulic conductivity; Asymmetrical VES.
Copyright (c) 2026 Abdulla K. Amin https://creativecommons.org/licenses/by-nc-nd/4.0
Gravimetric detection of sinkhole hazard at abandoned coal mine Čáry (Slovakia) using Growth inversion – preliminary results
Microgravimetry has been used in near surface investigations for detecting cavities. It has already proven its success in revealing unknown crypts and tombs in archaeological prospection. It was involved in searching for new cave spaces in karst. It was also employed in detecting void spaces in shallow-mining areas to mitigate sinkhole hazard. In our study we focus on the applicability, benefits and limitations of using the 3D Growth inversion approach for inverting the high-resolution high-precision micro-gravity data observed in undermined areas with the purpose of detecting shallow void space that could lead to sinkhole development, slow surface subsidence or collapses. Growth inversion has several free, user-specified inversion parameters that shape the Growth solution. Our case study presented here is related to sinkhole hazard due to abandoned shallow brown-coal mining under fields with agricultural activities. We pay attention to tuning these parameters for specific needs of cavity detection in terms of long and narrow shallow mining shafts.
near surface geophysics; 3D microgravimetry; inverse problem; subsurface voids; growing source bodies; sinkhole hazard
Copyright (c) 2026 Jozef Bódi, Peter Vajda, Pavol Zahorec, Roman Pašteka, Juraj Papčo, René Putiška, Bibiana Brixová, José Fernández https://creativecommons.org/licenses/by-nc-nd/4.0
Radon monitoring in the Harmanecká Cave, Slovakia
Radon survey in the Harmanecká Cave was conducted from December 2023 to November 2024 using Ramarn track detectors placed in 8 stations inside the cave and one station in the cavity developed in the same karst system outside the cave. Detectors were changed every three months. Annual average of radon activity concentration inside the cave varied between 930 and 2240 Bq/m3, in the cavity it was equal to 222.5 Bq/m3. Seasonal variation was observed at all sites, and its different character among sites was proven. A possible relation between radon and microclimate and meteorological parameters was investigated, but no clear relationship was observed. Assessing their possible effect on radon using three-month data is therefore not appropriate and continuous measurements are needed. Estimated annual effective dose for the cave guides was below the limit of 20 mSv.
radon; cace; track detector; monitoring; effective dose
Copyright (c) 2026 Iveta Smetanová, Lucia Pristašová, Dagmar Haviarová, Kristian Csicsay https://creativecommons.org/licenses/by-nc-nd/4.0
Aquifer potential zones within Akure, Nigeria, using geo-electrical derived parameters and GIS multi-criteria model approach
This research addresses the recurring issue of water scarcity during dry seasons in Akure metropolis, Nigeria—a crisis exacerbated by demographic growth, increasing domestic and industrial water demands, and groundwater overexploitation. Through comprehensive geophysical investigations, we developed a methodological framework to identify and spatially delineate zones of groundwater resource prospect. Our approach integrated multiple hydrogeological parameters derived from electrical resistivity surveys (transverse resistance, hydraulic conductivity, and aquifer transmissivity) with lineament density analysis from satellite imagery to create thematic spatial representations. These parameters were systematically weighted using the Analytical Hierarchy Process (AHP) within a multi-criteria decision analysis framework to construct a groundwater prediction mapping index. The results from the iso-resistivity map of the saprolite layer revealed areas with clayey aquifers, fractured/clayey aquifers, sand/clayey sand aquifers. The isopach map of the saprolite layer shows areas with low, medium, and high groundwater yield. The depth to basement surface layer map revealed areas with bedrock swells and locations with bedrock troughs which will be suitable for groundwater exploration. The resulting groundwater potential prediction model classified the investigated site into four specific categories: low, low-medium, medium, and medium-high potential zones. The results show that nearly 92% of the metropolitan zones exhibit relatively low groundwater prospects, with only 8% demonstrating suitable characteristics for sustainable extraction. This research provides critical spatial intelligence for identifying viable groundwater development zones and serves as a guide for local water authority bodies to reduce borehole failures.
groundwater prospect mapping, analytical hierarchy procedure, hydrogeophysics, geospatial analysis, basement aquifer systems
Copyright (c) 2025 Olubunmi Oluwatoyin OMOTOLA, Adewale Henry OLABINTAN https://creativecommons.org/licenses/by-nc-nd/4.0
Precise determination of gravity in geodetic networks in Slovakia – CBA2G approach
We present software for calculating gravity acceleration at points of levelling networks in Slovakia. The chosen approach uses an existing detailed gravimetric database and a back-calculation (reconstruction) of the gravity acceleration from the Bouguer anomaly map. We analyse the accuracy of this approach on a sample of independent geodetic points as well as in-situ control measurements.
gravity acceleration, complete Bouguer anomaly, levelling networks, ellipsoidal heights
Copyright (c) 2025 Pavol ZAHOREC, Juraj PAPČO, Miroslava JANČOVIČOVÁ, Ivan MARUŠIAK, Roman PAŠTEKA https://creativecommons.org/licenses/by-nc-nd/4.0
Impact of sea water intrusion on groundwater aquifers using geoelectrical techniques: A case study, the new port of Jarjob, El-Negila area, Marsa Matrouh, Egypt
This research investigates the effect of seawater intrusion on groundwater quality in the western coastal zone of the Mediterranean Sea, Egypt, between Wadi Abu Emera and Abu-Hesha. The objective of this research is to study the effect of seawater intrusion on groundwater quality, using geoelectrical techniques including vertical electrical resistivity soundings (VES) and time-domain electromagnetic methods (TEM). Ten Schlumberger VES with a current electrode distance of as high as 600 m and twenty TEM soundings with a single loop of 200 × 200 metres were carried out during this study. Processing and interpretation of the field data concluded that the geoelectrical succession of the area consists of three layers, where the bottom layer is the water-bearing formation. Also, the resistivity values decrease with depth and towards the Mediterranean Sea because of the seawater intrusion. This intrusion occurs along a system of faults that act as conduits to bring seawater inland. It is recommended to avoid the locations of these faults while drilling wells unless these wells are used for the desalination process. These faults serve as conduits for seawater to migrate inland. In contrast, the southern portion of the survey area is suitable for well drilling, provided that careful measures are implemented to maintain the wells' safe yield.
Mediterranean Sea, vertical electrical sounding, transient electromagnetic sounding, water quality, coastal environment
Copyright (c) 2025 Shimaa M. SALEM, Talaat Ali ABDELLATIF, Hosny M. Ezz EL DEEN, Islam N. EL-NEKHIELY, El-Arabi H. SHENDI https://creativecommons.org/licenses/by-nc-nd/4.0
Unveiling crustal intrusions and fault systems of southwestern Sokoto Basin through enhanced gravity analysis
The Sokoto Basin, a frontier basin area in northwestern Nigeria, has garnered significant attention due to its favourable prospects for oil and gas exploration. This study utilises potential field gravity data to investigate the depth architecture of the southwestern Sokoto Basin and provide insights into the emplacement mechanisms of its anomalous geological features. The Bouguer gravity anomaly reveals a regional gravity field dipping at approximately 10° northeasterly, with a gradient of 0.38 mGal/km. Residual Bouguer anomaly analysis identifies a prominent positive anomaly in the southern region and negative anomalies ranging from −74.88 mGal to −27.38 mGal. Integration of enhancement filters, forward modelling, and spectral analysis reveals that source depths increase towards the south. Gravity modelling indicates intrusions in the upper crust at depths of 10 to 20 km and 5 to 10 km. A 3D model assembled from the findings illustrates the basin's subsurface structure, supporting earlier works. The results suggest that Eocene sediments and Quaternary faults/fractures play critical roles in the area's hydrocarbon system. Ultimately, the quantitative analysis of the gravity maps reveals the presence of diverse structural features and their constituent components within the study area. Notably, the primary tectonic deformations exhibit trends oriented NW–SE, NE–SW, and E–W. This study significantly enhances our understanding of the subsurface architecture of the southwestern Sokoto Basin, offering crucial insights that will inform and optimise future hydrocarbon exploration initiatives.
gravity data, enhancement utilisation, depth estimation, geological structures, modelling, Sokoto basin
Copyright (c) 2025 Adamu ABUBAKAR, Othniel Kamfani LIKKASON, Abdulganiyu YUNUSA https://creativecommons.org/licenses/by-nc-nd/4.0
The lithospheric structure along profile Vyhne based on 2D integrated geophysical modelling (Western Carpathians, Slovakia)
We have used 2D integrated modelling method to derive a model of the lithospheric structure along profile Vyhne located in the Western Carpathians. The algorithm determines the thermal structure of the lithosphere that is controlled by other geophysical fields, namely by heat flow, topography, gravity and geoid data. Such approach allows us to distinguish between density variations at different depths. Integrated algorithm method focuses primarily on the analysis of deeper lithospheric structure, especially on the lithosphere–asthenosphere boundary (LAB). Beneath the European Platform and the Outer Western Carpathians, the LAB is nearly horizontal, lying at depths of approximately 115–118 km. Moving toward the Inner Western Carpathians, a modest increase in lithospheric thickness becomes apparent, along with the presence of a subtly developed lithospheric root, which may represent a small remnant of the upper part of the break-off subducted lithospheric slab. Based on the computed thermal structure of the lithosphere, we established a rheological model along this profile. We determined the lithospheric strength distribution (considering both brittle and ductile deformation) for compressional and extensional settings, calculated the vertically integrated strength, and constructed the yield-strength envelope for the tectonic environment of the Vyhne tidal station. Our findings clearly indicate that a compressional regime prevails, with the greatest strength beneath the European Platform and the Western Carpathians. Along the modelled profile, strength declines from the high values observed beneath the European Platform to a minimum within the Pieniny Klippen Belt before rising again to peak values beneath the Western Carpathians.
integrated geophysical modelling, heat flow, topography, gravity, geoid, lithosphere, asthenosphere, rheology, strength, Vyhne, tidal station, Western Carpathians
Copyright (c) 2025 Jana DÉREROVÁ, Miroslav BIELIK, Irina MAKARENKO, Olga LEGOSTAEVA, Igor KOHÚT, Jozef BÓDI https://creativecommons.org/licenses/by-nc-nd/4.0
Exploring mineralisation potential using geophysical, remote sensing and field studies in parts of the Migmatite-Gneiss complex, Kwara State, Nigeria
Gold mineralisation and enrichment of critical minerals can be found in placers and veins in the schist belts of the western part of Nigeria. The study area, Bielesin, Asa in Kwara State, experiences a preponderance of artisanal mining that targets the primary gold-quartz presence and associated alluvial occurrences due to the lack of any methodical exploration and development. Hence, this study focuses on preliminary exploration in the study area, which entails identifying geological indicators of mineralisation, and deploying gravity survey and remote sensing investigations to determine potential mineralisation structures. Geochemical analysis was utilised to determine the trace elemental composition of the samples. Vertical electrical sounding (VES) was used to ascertain the thickness of the deposit. The identified minerals in the migmatite gneiss include quartz, feldspar and tourmaline. The observed folded gneissose foliation, schollen and stromatic folds, pegmatites and quartzo-feldspathic veins, and lenses of biotite are indicative of anatexis, which allows for the formation of pegmatites. The valuable minerals occur as discrete grains disseminated in pegmatite and veins. The geological controls for the hosting and emplacement of the mineralisation are structural (faults, fractures). Several features were detected in the study area that could serve as structural controls for ore deposition from hydrothermal solutions or ascending magmatic intrusions. From the interpretation of 3D Euler deconvolution and resistivity results as well as the trenching, the potential auriferous mineralised zones extend from the low-lying quartz veins and pegmatites at depths of approximately 1 m to deep-seated mineralisations at >1000 m. This could help in tonnage estimation and the determination of equipment requirements for excavation activities. This study suggests the presence of gold mineralisation in the study area.
migmatite gneiss, Bouguer anomaly map, faults and fractures, Landsat imaging, lineaments, pegmatites and quartz veins, vertical electrical sounding
Copyright (c) 2025 Abdullah Musa ALI, Ahmed Alhassan AMINU https://creativecommons.org/licenses/by-nc-nd/4.0
Influence of regularized derivatives in edge detectors for qualitative magnetic field interpretation – a case study from northeastern Nigeria
This study applies a Tikhonov regularization framework to aeromagnetic data from parts of northeastern Nigeria to enhance the resolution of magnetic anomalies and suppress geological and cultural noise. The dataset, covering twelve geological map sheets acquired by Fugro Airborne Surveys (2004–2009), was processed using a range of derivative-based edge-detection filters, including the Horizontal Gradient (HG), Analytic Signal (AS) amplitude, Tilt, Horizontal Gradient of Tilt (HG_Tilt), Theta, Normalized HG (TDX), TDXAS, Tilt Angle of the Total Horizontal Gradient (TAHG), Enhanced Tilt (ETilt), Enhanced Total Horizontal Derivative of the Tilt Angle (ETHDR), and Modified Horizontal Gradient Amplitude (MHGA). The MHGA method was further optimized by varying a constant offset (often a fraction or multiplication of π in its computation to evaluate its sensitivity and performance. Results show that regularized derivatives effectively minimize noise amplification while preserving structural integrity, with a revisited algorithm (published by Karcol and Pašteka in year 2025) providing the most stable differentiation. The ETHDR and MHGA (−π/3) filters delineated low-magnetic anomaly zones associated with the Bima, Yolde, Pindiga, Gombe, and Kerri-Kerri Formations, indicating promising geothermal potential. High-gradient zones correspond to granitic intrusions and fault intersections that may act as heat sources and hydrothermal conduits. These results demonstrate that integrating regularized derivatives with advanced edge-detection filters significantly enhances geothermal prospectivity mapping in complex crustal settings.
Tikhonov regularization, aeromagnetic data, edge detection filters, northeastern Nigeria
Copyright (c) 2025 Ahmed Kehinde USMAN, Roland KARCOL, Roman PAŠTEKA https://creativecommons.org/licenses/by-nc-nd/4.0
Inversion of Rayleigh wave dispersion curve based on beluga whale optimization algorithm
Rayleigh wave exploration is a crucial technique in engineering site investigation for obtaining subsurface stratigraphic information. Inverting its dispersion curve can effectively reveal underground structures. However, traditional global optimization algorithms exhibit significant limitations in dispersion curve inversion, including slow convergence, low accuracy, and a tendency towards premature convergence. These issues hinder the precise interpretation of stratigraphic information and impact the efficiency and reliability of engineering surveys. To address these challenges, this paper introduces a novel global optimization algorithm—Beluga Whale Optimization (BWO)—for Rayleigh wave dispersion curve inversion, aiming to improve inversion effectiveness and enhance performance. BWO achieves optimal solution finding by mimicking beluga whale swimming, predation, and falling behaviours. Compared to other heuristic algorithms, BWO demonstrates favourable performance in solving complex functions, offering superior performance and efficiency while ensuring high solution accuracy, convergence speed, and stability. When testing the theoretical model of BWO applied to dispersion curve inversion, first, four noise-free models were used to verify the feasibility of BWO for dispersion curve inversion; subsequently, 15% random noise was added to the models, demonstrating that BWO has strong anti-interference capability; finally, specific multi-mode dispersion data were used to test that BWO can be applied to multi-order dispersion curve inversion. During the inversion of noise-free, noise-containing, and multi-mode dispersion models, BWO was compared with the Particle Swarm Optimization (PSO) algorithm, which proved that BWO has superior inversion performance and can obtain higher-precision solutions. In the actual data testing, seismic data from Wyoming, USA, were used to verify BWO's capability in processing actual data. Results from theoretical model tests and analysis of field data indicate that BWO possesses characteristics of speed, high accuracy, stability, and strong practicality, making it effectively applicable for the quantitative interpretation of Rayleigh wave dispersion curves.
Rayleigh wave, dispersion curve inversion, global optimization, beluga whale optimization (BWO)
Copyright (c) 2025 Fengjun WU, Xiaoyu WEI, KeRong HE, Gang LI, XinAi XU https://creativecommons.org/licenses/by-nc-nd/4.0
Potential induced along a pipeline during geomagnetic storms and geoelectric coast effect
The paper proposes a calculation method for the assessment of the induced potential along a pipeline, located nearby a coastline, due to the geomagnetic induction occurring during geomagnetic storms. The algorithm is based on the generalized thin sheet model to describe the inducing geoelectric field and on the transmission line model with lumped parameters to describe the pipeline under the influence of the geoelectric field which is supposed to have a generic polarization. In particular, the proposed calculation method allows for the assessment of the potential profile that can be generated along the pipeline and for the identification of the zones, along the pipeline layout, that are more exposed to the occurrence of high electric potentials. We remind that the overpotentials generated along the infrastructure can interfere with the pipeline cathodic protection and with the electrical survey apparatuses, thus affecting their correct functioning and so increasing the corrosion risk. Therefore, this model can be an aid, also at the design stage of a new infrastructure, able to individuate the riskiest zones, along the pipeline layout, subjected to the highest induced potentials so allowing to minimize the threaten represented by geomagnetic storms. The peculiarity and novelty of the paper, differently from previous works, is the taken account of the geoelectric coast effect in the assessment of the induced potential profile along the pipeline route by means of an approach that is based on the generalized thin sheet model under a generic state of polarization of the inducing geomagnetic field.
Geomagnetic storms; Telluric currents; Geomagnetically induced currents; Pipelines; Geoelectric coast effect
Copyright (c) 2026 Giovanni Lucca https://creativecommons.org/licenses/by-nc-nd/4.0
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
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
Copyright (c) 2012 Milan HVOŽDARA 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
Copyright (c) 2012 Viliam ŠIMOR, Kamila HLAVČOVÁ, Silvia KOHNOVÁ, Ján SZOLGAY https://creativecommons.org/licenses/by-nc-nd/4.0
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
Copyright (c) 2012 Ľudovít KUCHARIČ, Vladimír BEZÁK, Dušan MAJCIN, Ján VOZÁR https://creativecommons.org/licenses/by-nc-nd/4.0
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
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
Copyright (c) 2012 Jana DÉREROVÁ, Igor KOHÚT, Miroslav BIELIK, Marián BOŠANSKÝ, Barbara PORUBČANOVÁ https://creativecommons.org/licenses/by-nc-nd/4.0
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 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
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
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
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