Seismic methods constitute indispensable tools for characterizing subsurface structures in near-surface geophysical investigations. To address the inherent challenges associated with the joint inversion of Rayleigh wave dispersion curves and seismic refraction data, this study introduces an Enhanced Beluga Whale Optimization (EBWO) algorithm incorporating two principal advancements. A hybrid initialization scheme combining Tent chaotic mapping and reverse learning strategies is adopted to substantially enrich population diversity, thereby overcoming the limitations of purely random initialization employed in the original Beluga Whale Optimization (BWO). The performance of EBWO is systematically evaluated through a two-stage validation framework. First, benchmark tests on four complex multimodal functions demonstrate that EBWO achieves superior convergence accuracy and enhanced solution stability relative to the standard BWO. Subsequently, synthetic joint inversion experiments under both noise-free and noise-contaminated conditions further verify its robustness and reliability, with EBWO consistently outperforming both BWO and Particle Swarm Optimization (PSO). The applicability of the proposed approach is further demonstrated using field data sets from Türkiye, where EBWO yields lower data misfits, improved agreement with independent geophysical interpretations and available geological constraints, and greater inversion stability. By integrating surface wave dispersion and refraction datasets within a unified inversion framework, EBWO effectively exploits their complementary sensitivities, thereby alleviating the non-uniqueness inherent in single-method inversions. Overall, the results highlight the efficacy and robustness of EBWO for near-surface characterization and underscore its considerable potential for broader applications in multi-parameter geophysical inversion.
The HOMEROS project advances multi-hazard assessment through the integrated use of seismological and geodetic infrastructures within an Open Science framework. This paper presents the seismological and GNSS-based geodetic networks, data products, and processing workflows that underpin hazard monitoring and analysis in tectonically active regions of Greece, with emphasis on the central Ionian Islands and the western Gulf of Corinth. Dense permanent seismic networks provide high-resolution waveform data enabling precise earthquake detection, relocation, and source characterization. Complementary GNSS infrastructures, such as the Hermes network and GL-NKUA cGNSS, deliver continuous observations processed using Precise Point Positioning and kinematic techniques to quantify crustal deformation displacements, and atmospheric parameters. Integrated quality control, standardised processing pipelines, and interoperability through EPOS, EIDA, and institutional repositories ensure compliance with the FAIR data principles. The combined seismological and geodetic datasets support advanced applications, including high-accuracy earthquake catalogues, deformation monitoring, and physics-based ground motion simulations for seismic hazard assessment, demonstrated through seismic crises in the study areas. By harmonising heterogeneous observations and products, HOMEROS enhances reproducibility, data reuse, and collaborative research, providing a robust testbed for multi-hazard assessment in Greece and a transferable model for the broader European and global research community.
Total gamma ray logs of Al-Wastani Formation clastic sediments were normalised across seven wells in the Sapphire oil field, situated in the deep marine area of the Mediterranean Sea, Egypt, to facilitate the computation of radiogenic heat production (RHP). The gamma ray logs were normalised via the Histogram method by manually modifying values for each well, with modifications varying from (-6 to +6) API. The Arithmetic mean and standard deviation of RHP values, which range from 0.05 to 1.67 & micro;W/m(3) were calculated as 0.71 & micro;W/m(3) and 0.23 & micro;W/m(3), respectively as established through statistical analysis of the data. Considering the strong relationship between RHP and hydrocarbon composition, the three-dimensional slicing of radiogenic heat production reveals that the upper portion of the Al-Wastani Formation constitutes a free-hydrocarbon zone. Hydrocarbons are present in both the intermediate and lower strata. Hydrocarbons are distinctly associated with reservoir rocks in the middle region of the Al-Wastani Formation. The lower layer of the Al-Wastani Formation is considered a source rock.
To assess regional climate models' ability to simulate future climate, their ability to represent observed historical climate should be evaluated first. This article evaluates the performance of 8 ERA-Interim reanalysis driven EURO-CORDEX regional climate models, comparing their simulations of daily precipitation totals, daily temperature averages, maxima and minima over Slovakia to gridded observations dataset CarpatClim. Slovakia has complex orography, ranging from lowlands to high mountains (94 to 2654 m ASL). The evaluation of regional climate models in this study is detailed, examining both ensemble and individual model bias, including bias in spatial and temporal distribution. The results of the evaluation show that precipitation and temperature are represented relatively well by the regional climate model ensemble. Despite that, the ensemble shows bias: for precipitation namely wet bias for winter and dry bias for summer precipitation, weaker precipitation-elevation correlations, overestimation of longer dry spells occurrence, and underestimation of longer wet spells occurrence; for temperature namely warm bias of hot extremes, overestimation of the annual cycle amplitude, general underestimation of daily temperature maxima, and overestimation of longer heatwaves and cold spells occurrence. The model ensemble average generally outperforms any single model. Notable individual model biases include the lack of representation of precipitation-elevation correlations by REMO2015 and a strong underestimation of temperature by RACMO22E.
The paper proposes a calculation method for assessing the potential along a pipeline located near a coastline, due to the geomagnetic induction occurring during geomagnetic storms. The algorithm is based on the generalised thin sheet model to describe the inducing geo electric field and on the transmission line model with lumped parameters to describe the pipeline under the influence of the geo electric field, which is supposed to have a generic polarisation. 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 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 electrical survey apparatuses, 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 potentials thus allowing to minimise the threaten represented by geomagnetic storms. The peculiarity and novelty of the paper, different from previous works, is the consideration of the geo electric coast effect in the assessment of the potential profile along the pipeline route using an approach based on the generalised thin sheet model under a generic state of polarisation of the inducing geomagnetic field.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
