Near surface Geophysics Research Papers (original) (raw)

2025, Bulletin of Earthquake Engineering

Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the V S,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical

2025, Geothermics

Guðmundur Pálmason became director of the Geothermal Division in 1964, and was to hold this position until he retired in 1997. During this period the geothermal industry in Iceland expanded enormously, the percentage of geothermal heating in Iceland increasing from 30 to 40% of all house heating to almost 90%; the high-temperature geothermal fields were also exploited to generate electricity. Under Guðmundur's management, the Geothermal Division grew from a small workplace with a few employees to a group of over 40 experts involved in almost all the geoscience and engineering disciplines related to the exploration and utilisation of geothermal resources.

2025, Proceedings of the World …

Electrical and electro-magnetic methods have been used extensively to identify and delineate high-temperature geothermal reservoirs in Iceland. All hightemperature systems, within the basaltic crust in Iceland, have a similar resistivity... more

2025

Effective exploration techniques during mechanized tunneling are of high importance in order to prevent severe surface settlements as well as a damage of the tunnel boring machine, which in turn would lead to additional costs and a standstill in the construction process. A seismic methodology called full waveform inversion can bring a considerable improvement compared to state-of-the-art seismic methods in terms of precision. Another method of exploration during mechanized tunneling is to continuously monitor subsurface behavior and then use this data to identify disturbances through pattern recognition and machine learning techniques. Various probabilistic methods for conducting system identification and proposing an appropriate monitoring plan are developed in this regard. Furthermore, ground conditions can be determined by studying boring machine data collected during the excavation. The active and passive obtained data during performance of a shield driven machine were used to estimate soil parameters. The monitoring campaign can be extended to include above-ground structural surveillance as well as terrestrial and satellite data to track displacements of existing infrastructure caused by tunneling. The available radar data for the Wehrhahn-line project are displayed and were utilized to precisely monitor the process of anticipated uplift by injections and any subsequent ground building settlements.

2025, Near Surface Geophysics

ABSTRACTWe obtain the transverse electric (TE) and transverse magnetic (TM) Fresnel reflection coefficients for different interfaces in the subsoil: air/fresh‐water, air/seawater, fresh‐water/seawater, air/NAPL (non‐aqueous phase liquid), NAPL/water and water/NAPL. We consider a range of NAPL saturations, where the complementary fluid is water with 0.65 ppt (parts per thousand) of NaCl. The common feature is that the TM mode (parallel polarization) has a negative anomaly and the TE mode (perpendicular polarization) has a positive anomaly. For the cases studied in this work, pseudo‐Brewster angles appear beyond 40° for the air/NAPL and NAPL/water interfaces and at near offsets (below 40°) for the water/NAPL interface. Pseudo‐critical angles are present for the water/NAPL interface. Besides the reflection strength, the phase angle can be used to discriminate between low‐ and high‐conductivity NAPL, when the properties of the upper medium are known. A wavenumber–frequency domain method...

2025, Scientific Reports

This study is to assess the natural radioactivity level in soil samples in communities bordering the Tano Basin in Ghana. The radioactivity concentration of 238U, 232Th and 40K have been determined using γ-ray spectrometry, moreover, the absorbed dose rates and annual effective dose were calculated. MATLAB R2013 script was written to simulate the decay of the radionuclides 238U, 232Th and 40K using their respective half-lives. This is to determine the future impact of natural radionuclides and estimate future anthropogenic inputs. The level 238U, 232Th, and 40K ranged from (1.60 to 21.3), (2.78 to 32.2) and (111 to 528) with average values of be 8.65 Bqkg−1, 12.5 Bqkg−1 and 214 Bqkg−1 respectively in soil. The activity concentrations were lower than United Nations Scientific Committee on the Effects of Atomic Radiation guidelines for 238U, 232Th and 40K. The absorbed dose rates and annual effective dose were found to be in range of 7.79 to 37.8 nGy h−1 and 9.56E + 00 to 4.64E + 01 µ...

2025

In geoscience, manually picking fractures and bedding from Formation Micro-Imager (FMI) logs is labour-intensive, requiring substantial time and effort. This study addresses the critical need for an automated solution to streamline this picking and identification process, emphasizing the significance of expediting reservoir characterization and decision-making in the petroleum industry. The model presented here aims to provide a quick turnaround of results delivery while significantly reducing the manual workload by automating the identification of fractures and beddings. The study leverages a comprehensive dataset comprising FMI logs from 14 vertical wells in Oman. The methodology adopts an advanced Fracture Detection Model based on the Detection Transformer architecture, customized to the unique requirements of the study. Precision, Recall, and F1-Score are key evaluation metrics computed through a tailored confusion matrix and depth thresholding for nuanced predictions. Our results are validated through different depth thresholds for fractures and beds. Sensitivity tests reveals that 8cm threshold generates a recall ~85% in comparison to 4cm threshold of ~75%. Visual analyses, performance metrics, and comparative plots underscore the model's proficiency in accurately identifying subsurface features. This Fracture Detection Model, validated through testing on several wells, stands out as an efficient and accurate automated tool for reservoir characterization.

2025, Japan Geoscience Union

2025, Carpathian Journal of Earth and Environmental Sciences

Groundwater resources in the region serve as a vital source of potable water for local communities and are essential for supporting various socioeconomic activities. Unfortunately, the infiltration of leachate from dumpsite contributes to the dispersion of contaminants within the cretaceous sediments, posing a potential threat to groundwater quality. This study presents an exhaustive examination of leachate extent emanating from a prominent dumpsite situated within the Cretaceous sediments of the Ikom-Mamfe Embayment, Southeast Nigeria. Employing meticulous soil sampling methodologies and water collection from strategically positioned boreholes near the Ikom dumpsite, advanced techniques such as Electrical Resistivity Tomography (ERT) and Vertical Electric Sounding (VES) were utilized to scrutinize the infiltration of leachate within the site. Laboratory analyses were conducted to evaluate the concentrations of heavy metals, including Lead, Mercury, Arsenic, Nickel, Chromium, and Cadmium, in both soil and borehole water samples. The findings unveiled alarming levels of Lead and Cadmium concentrations in the soil, exceeding established regulatory thresholds, with recorded values ranging from 552.34 to 556.93 mg/kg and 11.88 to 7.46 mg/kg, respectively. Similarly, borehole water analyses in the vicinity of the Ikom dumpsite revealed elevated concentrations of Arsenic, Lead, Cadmium, and Nickel, surpassing WHO limits in specific boreholes (BH2 and BH3), indicative of potential soil porosity issues and unfavorable geological conditions prevalent in the study area. Notably, the use of ERT delineated an inverse resistivity of 5.99 Ωm at a depth of 9.26 m, pinpointing the leachate-infiltrated cretaceous sediments zone, extending laterally from 10m to 40m along the profile. The observed infiltration of leachate at 9.26 m depth underscores its penetration into the sandstone, shale, and dark gray shale strata within the dumpsite. Furthermore, the quantified thickness layer ranging from 1.41 to 4.37 affirmed leachate infiltration within the sandstone, shale, and dark gray shale strata, with implications for its movement and containment dynamics. This study underscores the critical role of layer thickness in influencing the migration and containment of leachate, with thicker layers potentially acting as barriers to its movement, while thinner layers may facilitate more rapid migration. Additionally, the assessment of aquifer protective capacity, denoted by ratings below (<0.1), underscores the poor protective capacity of the aquifer system in the study area. In light of these findings, strategic management, remediation, and vigilant monitoring measures are advocated to mitigate contamination risks and safeguard water quality.

2025, Archaeological Prospection

In spite of an increase in World War I (WWI)-related excavations in Flanders (Belgium), little is known about the nature and extent of the buried heritage of WWI from research on a landscape scale. This paper examines the combination of historical aerial photographic evidence and geophysical soil sensing. A case study in Comines-Warneton compares data derived from contemporary WWI aerial photographs with multi-receiver electromagnetic induction surveys. This comparison provides an understanding of the degree of preservation of trenches, dugouts and other military structures, and illustrates the added value of integrating both techniques in an in-depth, non-invasive study of conflict landscapes.

2025

Oil prospecting requires images of the subsurface. Among measurements that are made to obtain those images, the seismic method consists in studying the propagation time of low frequency (10 200 Hz) elastic waves between a source and a receiver, both located at the surface or buried. A recent development in seismic is time lapse or 4Dsurveying which aims at monitor the changes in the subsurface in time. To achieve this, measurements are repeated with the same three dimensional configuration: reliability and repeatability of the acquisition footprint are key requirements for 4D surveys.

2025

Arranged from oldest to youngest, the main granitic rock units exposed in Khour Abalea are metagabbros, cataclastic rocks, ophiolitic melange, granitic rocks, pegmatite and lamprophyre dykes. The presence of radioactivity associated with the heavy bearing minerals in construction materials-like granite-increased interest in the extraction process. As it turns out, granitic rocks play an important economic part in the examination of an area's surroundings. The radionuclide content is measured by using an NaI (Tl)-detector. In the mineralized pegmatites, U (326 to 2667 ppm), Th (562 to 4010 ppm), RaeU (495 to 1544 ppm) and K (1.38 to 9.12%) ranged considerably with an average of 1700 ppm, 2881.86 ppm, 1171.82 ppm and 5.04%, respectively. Relationships among radioelements clarify that radioactive mineralization in the studied pegmatites is magmatic and hydrothermal. A positive equilibrium condition confirms uranium addition to the studied rocks. This study determined 226 Ra, 232 Th and 40 K activity concentrations in pegmatites samples and assessed the radiological risks associated with these rocks. The activity concentrations of 226 Ra (13,176 ± 4394 Bq kg-1), 232 Th (11,883 ± 5644 Bq kg-1) and 40 K (1573 ± 607 Bq kg-1) in pegmatites samples (P) are greater than the global average. The high activity of the mineralized pegmatite is mainly attributed to the presence of uranium mineral (autunite), uranophane, kasolite and carnotite, thorium minerals (thorite, thorianite and uranothorite) as well as accessories minerals-such as zircon and monazite. To assess the dangerous effects of pegmatites in the studied area, various radiological hazard factors (external, internal hazard indices, radium equivalent activity and annual effective dose) are estimated. The investigated samples almost surpassed the recommended allowable thresholds for all of the environmental factors.

2025, Open Geosciences

This study evaluates the impact of seepage on the integrity of artificial levees in low-lying regions, with a particular focus on Hungary, where levees built over a century ago lack comprehensive construction documentation, complicating current assessments of their effectiveness. Advanced geophysical methodselectrical resistivity tomography (ERT) and ground-penetrating radar (GPR)-were applied in a controlled tank experiment designed to simulate varied flood conditions along a 37-m levee section. The three-dimensional (3D) ERT profiles successfully delineated seepage pathways as the tank filled, while the 3D GPR profiles indicated areas of increased amplitude, corresponding to seepage zones and the water table. Validation through drilling confirmed the geophysical findings, underscoring the accuracy of ERT and GPR in non-destructively identifying subsurface features and seepage channels. The results highlight the applicability of these methods for evaluating levee integrity and seepage dynamics, offering a reliable approach for flood risk assessment in Hungary and similar flood-prone areas worldwide.

2025, cuee.titech.ac.jp

Graduate student, Department of Built Environment, Tokyo Institute of Technology, Japan 2) Professor, Department of Built Environment, Tokyo Institute of Technology, Japan 3) Professor, Department of Urban Environment Systems, Chiba... more
Graduate student, Department of Built Environment, Tokyo Institute of Technology, Japan 2) Professor, Department of Built Environment, Tokyo Institute of Technology, Japan 3) Professor, Department of Urban Environment Systems, Chiba University, Japan 4) ...

2025, CCA, 2024

During the campaign of 2024, the entire surface was re-opened, except for the initia trench explored in 2018. The results confirmed the substructure of a N-S road, a previous phase of via praetoria that cannot be precisely dated until... more

2025, Near Surface Geophysics

To reduce both the computational cost of probabilistic inversions and the illposedness of geophysical problems, model and data spaces can be reparameterized into low-dimensional domains where the inverse solution can be computed more efficiently. Among the many compression methods, deep learning algorithms based on deep generative models provide an efficient approach for model and data space reduction. We present a probabilistic electrical resistivity tomography inversion in which the data and model spaces are compressed through deep convolutional variational autoencoders, while the optimization procedure is driven by the ensemble smoother with multiple data assimilation, an iterative ensemble-based algorithm. This method iteratively updates an initial ensemble of models that are generated according to a previously defined prior model. The inversion outcome consists of the most likely solution and a set of realizations of the variables of interest from which the posterior uncertainties can be numerically evaluated. We test the method on synthetic data computed over a schematic subsurface model, and then we apply the inversion to field measurements. The model predictions and the uncertainty assessments provided by the presented approach are also compared with the results of a Markov Chain Monte Carlo sampling working in the compressed domains, a gradient-based algorithm and with the outcomes of an ensemble-based inversion running in the uncompressed spaces. A finite-element code constitutes the forward operator. Our experiments show that the implemented inversion provides most likely solutions and uncertainty quantifications comparable to those yielded by the ensemble-based inversion running in the full model and data spaces, and the Markov Chain Monte Carlo sampling, but with a significant reduction of the computational cost.

2025, Near Surface Geophysics

ABSTRACTElectrical resistivity tomography is an ill‐posed and nonlinear inverse problem commonly solved through deterministic gradient‐based methods. These methods guarantee a fast convergence towards the final solution, but the local linearization of the inverse operator impedes accurate uncertainty assessments. On the contrary, numerical Markov chain Monte Carlo algorithms allow for accurate uncertainty appraisals, but appropriate Markov chain Monte Carlo recipes are needed to reduce the computational effort and make these approaches suitable to be applied to field data. A key aspect of any probabilistic inversion is the definition of an appropriate prior distribution of the model parameters that can also incorporate spatial constraints to mitigate the ill conditioning of the inverse problem. Usually, Gaussian priors oversimplify the actual distribution of the model parameters that often exhibit multimodality due to the presence of multiple litho‐fluid facies. In this work, we dev...

2025, Near Surface Geophysics

ABSTRACTIn this paper, we discuss the necessity of quantifying and correcting seasonal 3D effects on 2D electrical resistivity tomography (ERT) data measured along the embankments of rivers or artificial canals. A permanent ERT monitoring system has been continuously operating along the levee of an irrigation canal in Mantua province, Italy, since September 2015. To evaluate the importance of 3D effects and their dependence on seasonal variations, we first performed numerical simulations and also laboratory tests on downscaled levees of the study site. The results showed that 2D apparent resistivity pseudosections measured along the levee are significantly affected by 3D effects of the embankment geometry. Moreover, it was observed that 3D effects not only depend on the levee geometry, but they are also affected by seasonal fluctuations in the water level in the canal. This proved the importance of calculating 3D effects for the study site during dry and irrigation periods. Therefor...

2025, AGU Fall Meeting Abstracts

The structural approach to joint inversion, entailing common boundaries or gradients, offers a flexible way to invert diverse types of surface-based and/or crosshole geophysical data. The cross-gradients function has been introduced as a means to construct models in which spatial changes in two models are parallel or anti-parallel. Inversion methods that use such structural constraints also provide estimates of non-linear and non-unique field-scale relationships between model parameters. Here, we invert jointly crosshole radar and seismic traveltimes for structurally similar models using an iterative non-linear traveltime tomography algorithm. Application of the inversion scheme to synthetic data demonstrates that it better resolves lithological boundaries than the individual inversions. Tests of the scheme on observed radar and seismic data acquired within a shallow aquifer illustrate that the resultant models have improved correlations with flowmeter data than with models based on individual inversions. The highest correlation with the flowmeter data is obtained when the joint inversion is combined with a stochastic regularization operator, where the vertical integral scale is estimated from the flowmeter data. Point-spread functions shows that the most significant resolution improvements of the joint inversion is in the horizontal direction. To determine petrophysical properties, state variables, and structural boundaries, it may be necessary to combine information provided by models obtained from different geophysical data (e.g., . Interpretation of several individually inverted data sets can be illuminating, but the results are usually affected by the resolution limitations of each model. For consistent interpretations of multiple geophysical models, it would be advantageous to have inversion tools that have similar formulations of the inverse problem regardless of the type of geophysical data being inverted. This would allow models to be coupled, as long as the data have comparable spatial support. By joint inversion, we refer to coupled models that are obtained by simultaneously minimizing a misfit function that includes the data misfit of each data type. Joint inversion can improve the resolution of each geophysical model and provide models that are consistent with each other and therefore easier to interpret (e.g., ). is not yet a standard tool in geophysical applications, mainly because robust and well-established petrophysical models that can be used to couple the models are usually only available for certain geophysical parameters, such as compressional and shear wave slownesses . Furthermore, petrophysical models often apply only in restricted geological settings (e.g., . In addition, the parameters of petrophysical models can seldom be adequately constrained by individual field data sets, such that fairly strong assumptions are required to couple models based on their petrophysical properties. To avoid introducing questionable petrophysical models, joint inversion methods have been developed for layered (1D) structures that are expected to have coincident layer boundaries and constant properties within each layer (e.g., Monteiro Santos et al., 2006). A

2025, Near Surface Geophysics

The Swedish Nuclear Waste Management Company (SKB) plans to build a repository for storage of high‐level radioactive spent nuclear fuel at the Forsmark site in central Sweden at a depth of about 470 m. The planned repository will cover an area of about 3.6 km2 at this depth. Prior to beginning excavation and tunneling, some detailed geophysical surveys are being performed at the planned site. One of these was a refraction seismic survey to determine depth to bedrock in the vicinity of the planned access ramp. Two lines, each about 300 m long and spaced about 35 m apart, were acquired in August 2011. Since the bedrock topography is known to be highly variable, a close receiver (2 m) and source (6 m) spacing was required to map it. This close spacing allowed the data also to be treated as reflection seismic data and some adjustments to the acquisition procedure were made in the field with this in mind to aid in the later processing. The main adjustment was that seismic data were recor...

2025

Geoelectrical and hydrogeological data were used to delineate and characterize the regolith aquifers in a hardrock area (Oban massif, Nigeria). Groundwater chemistry in the area is controlled by silicate weathering and ion exchange. The water in the area is good for domestic and irrigation applications. The study also includes management issues for the area. Introduction and objectives The development of groundwater resources in the Oban massif basement complex area has been the focus of the government without much success due to the fact that basement complexes are problematic aquifers. Therefore this study was to contribute to groundwater development in a hardrock area.

2025, Springer Natural Hazards

The Springer Natural Hazards series seeks to publish a broad portfolio of scientific books, aiming at researchers, students, and everyone interested in Natural Hazard research. The series includes peer-reviewed monographs, edited volumes, textbooks, and conference proceedings. It covers all categories of hazards such as atmospheric/climatological/oceanographic hazards, storms, tsunamis, floods, avalanches, landslides, erosion, earthquakes, volcanoes, and welcomes book proposals on topics like risk assessment, risk management, and mitigation of hazards, and related subjects.

2025

This study focuses on the infrastructure vulnerability at selected gas regulatory station of Dhaka city which includes all of the stations and important feeding stations around Dhaka. For this purpose, vulnerability of 23 gas stations are determined by comparing characteristic site period of soil and structural periods of buildings constructed within 300 m radius of gas stations. Shear wave velocities are determined by microtremor array method by analyzing recorded data with computer program Geopsy. Shear wave velocities of gas stations are taken as input parameter to determine site periods. Shear wave velocity determined by this method is verified by SPT N values of eight gas stations. Average shear wave velocity of top 30m (VS30) is determined by BNBC 2017 (proposed) and IBC 2009 methods from which Characteristic site period of gas stations are estimated. The periods of buildings are determined based on empirical formula provided by BNBC 2006, NEHRP 2003, ATC 3-06, 1978, NZSEE (20...

2025, Recent Advances in Natural Sciences 1 (2023) 25

Mayo-Belwa Local Government Area has been reported to have deposits of Uranium; hence this study was carried out to measure radionuclide activities in Mayo-Belwa soils and to monitor their potential impact on human health. Soils from a depth of 10 cm were collected from each location, using CANBERA NaI (Tl) detector, the activity concentration of radionuclides of 10 soil samples was measured. The radionuclide concentration ranged between 72.7069-116.8504 Bq.kg-1 for 238 U (measured by 226 Ra activity), 148.9168-981.4994 Bq.kg-1 for 40 K and 22.3332-108.5203 Bq.kg-1 for 232 Th. The gamma absorbed dose rate, annual effective dose rate, ranged between 61.3932-138.1076 nGyh-1 , 0.0830-0.211 mSvy-1 with mean values of 95.1762 ± 21.5257 and 0.1216 ± 0.0359 respectively. The values obtained were compared with the reported data from UNSCEAR, 2000 and ICRP 2005. The excess lifetime cancer risk ranged between 0.00026-0.00061 with an average value of 8.44×10-4. The gamma, internal and external hazard indices ranged between 0.4631-1.0975, 0.5969-0.9978 and 0.3601-0.8087 respectively. However, dose rates recorded in all locations were above the 60 nGyh-1 recommended limits by UNSCEAR 2000. Furthermore, Ganglare had a gamma index above 1, implying a significant radiation hazard. Also, the average excess lifetime cancer risk (ELCR) of 0.844 × 10-3 was relatively high (t < 0.05) and compared to the world average value of 0.29 ×10-3. With the help of this study, we were able to establish the fundamental facts about the levels of radioactivity and related radiological dangers that exist in the soil of Mayo-Belwa Local Government.

2025, Near Surface Geophysics

ABSTRACTDirect current resistivity and time‐domain electromagnetic (TDEM) surveys are often used in environmental, hydrological and mining evaluation. The interpretation of the data acquired with each of these geophysical methods, assuming one‐dimensional models, frequently produces ambiguous results. The joint inversion of TDEM and direct current resistivity data is considered by several authors as an efficient method to reduce the ambiguity inherent to each of these methods. This paper presents the results of a comparative study on the use of a local optimization method, iteratively reweighted least squares and global optimization methods of simulated annealing and particle swarm optimization in the joint inversion of TDEM and direct current resistivity data. The models obtained from joint inversion of synthetic data (H‐ and K‐type) and of experimental data using the three methods yield similar results. The iteratively reweighted least squares method is the fastest while the simul...

2025

Die Induzierte Polarisation (IP) ist ein geoelektrisches Verfahren und wurde ursprünglich zur Exploration von Erzvorkommen entwickelt. Neben metallischen Leitern, tragen auch Tonminerale, der Porenraum und die chemische Zusammensetzung der Porenlösung zur Polarisierbarkeit eines Unter-grundes bei. Die spektrale Induzierte Polarisation (SIP) untersucht die Polarisierbarkeit in einem Frequenzbereich von 1 mHz bis 1 kHz und nutzt diese aufgezeichneten Spektren zur Unterscheidung von Materialien. Früher mit einem enormen messtechnischen Aufwand verbunden, führte der gerätetechnische Fort-schritt in den letzten beiden Jahrzehnten dazu, dass die SIP vermehrt in der Umweltgeophysik zum Einsatz kommt. Zu den Fragestellungen gehören die Detektion von Altlasten und der Grundwasser-schutz. In der Archäologie ist die Induzierte Polarisation bislang ein kaum verwendetes Verfahren. Im Rahmen des Graduiertenkollegs „Archäologische Analytik“ der J. W. Goethe- Universität wurde die Entwicklung einer...

2025, Technical report

Seismographs have recorded ground motion since the end of the 19th century until digital recordings became available in the 1970s. Pre-digital seismic records were typically created by using ink on white paper, scratching black-smoked paper, or by using light on photographic paper. With most of these legacy seismic data now stored in archives and exposed to physical decay, several projects in the last 20 years started to dedicate resources to digitising them to preserve and exploit the unexplored scientific wealth they contain and, in turn, introduce them into the age of modern seismology. This effort has become increasingly important due to the increasing risk of permanently losing those ageing paper seismograms combined with their recently found exclusive potential in recovering the global oceanic climate for the last century. The Royal Observatory of Belgium (ROB) possesses a vast archive of legacy seismic data, some of which has recently been scanned. Our project used computer vision and recently developed machine learning approaches to digitise waveform data extracted from these scanned images. This process results in the creation of calibrated and time-coded seismic time series, which can subsequently be disseminated to the scientific community via international web services following seismic community-defined standards. By providing access to continuous seismic data spanning the past century following the FAIR principles (findability, accessibility, interoperability, and reusability), the project aims to facilitate the investigation of historical oceanic climates using seismic data and to improve the accessibility to tools necessary for the digitization efforts across various institutes, observatories, and universities. Furthermore, the broad availability of quantitative observational data from around the world will significantly enhance existing oceanic wave models of the 20th century, contributing to climate research. We meticulously compiled all the information on the seismic archive of the ROB, along with its metadata. Our decision to concentrate on Galitzin data was informed by the instruments' high response in the microseismic frequency band, rendering them ideal proxies for sea state analysis. We developed an algorithm to vectorize and extract digital seismic waveforms from scanned seismograms using traditional computer vision techniques, supplemented by a distinct module leveraging deep neural networks to address more complex scenarios, such as line inter-crossing induced by high-amplitude events like earthquakes. We also developed a tool to compare vectorized waveforms with theoretical microseismic ground motions derived from the WaveWatch III oceanic models, facilitating initial validation of the time series. The work conducted within this project is continually evolving to ensure its enduring utility for the widest possible audience. Furthermore, the project has made significant contributions to the broader scientific community through the establishment of working groups, participation in international initiatives, provision of training courses, and ongoing contributions to a book chapter.

2025, Near Surface Geophysics

ABSTRACTSpectral induced polarization signatures have been used as proxies for microbial abundance in subsurface environments, by taking advantage of the charged properties of microbial cell membranes. The method's applicability, however, remains qualitative, and signal interpretation ambiguous. The adoption of spectral induced polarization as a robust geo‐microbiological tool for monitoring microbial dynamics in porous media requires the development of quantitative relationships between biogeochemical targets and spectral induced polarization parameters, such as biomass density and imaginary conductivity (σ″). Furthermore, deriving cell density information from electrical signals in porous media necessitates a detailed understanding of the nature of the cell membrane surface charge dynamics. We present results from a fully saturated sand‐filled column reactor experiment where Shewanella oneidensis growth during nitrate reduction to ammonium was monitored using spectral induced ...

2025, Near Surface Geophysics

ABSTRACTLutetian limestones have been widely used in historical monuments within the Paris Basin during the course of the medieval and modern periods. Among the physical properties that can be used to assess the evolution of the limestonesin situin the buildings and their present health, the complex effective permittivity in the 10–100 kHz frequency range is easy to measure and reflects the internal structure of the stone along with the dependence on the water content. To improve our knowledge about this property, a laboratory study on four samples collected in the relevant quarries has been undertaken using measurements in the 100 Hz–10 MHz frequency range. Except close to zero water content, the observed results exhibit a quasi‐absence of variation of the real effective permittivity with the water content. The frequency variation fits fairly well with a model taking into account a Jonscher's decrease, a direct current conductivity, a high‐frequency dielectric permittivity and ...

2025, GEOPHYSICS

The detection and characterization of buried cables and metal pipes has become a key component of field surveys carried out prior to excavation work on construction sites. The very high conductivity and magnetic permeability contrast between any buried cables/pipes compared with the soil makes electromagnetic induction (EMI) instruments very useful for their detection. We have developed a seminumerical method that can be used to model the responses of this type of target. A straight horizontal conductor is equivalent to a series of magnetic dipoles, the magnitude of which can be determined in the spectral domain and then converted back into the spatial domain through the use of an inverse fast Fourier transform. Simulations and case studies allow to establish rules of thumb for the estimation of (1) the nature of the metal: the in-phase response of magnetic cables is of the opposite sign from the conducting ones, (2) the sensitivity to the target characteristic: the influence of the...

2025, Archaeological Prospection

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2025, Minerals Engineering

Flotation is a separation process in which a hydrophobic material is separated from a hydrophilic one. It is commonly used in several branches of processing. The purpose of this paper was to use three dimensional Electrical Resistance Tomography (ERT) for the measurement of the spatial distribution of gas holdup in a mechanical flotation cell. Using an array of metal electrodes installed on the wall of the cell, a set of electric currents was injected to the cell and the resulting voltages were measured. The electrical conductivity within the cell was estimated based on the known currents and measured voltages. The gas holdup distribution was computed based on Maxwell model. The method was tested in a 50 dm 3 mechanical flotation cell filled with water. The gas holdup distribution is presented at various values of the rotor speed and gas superficial velocity in non-frothed and frothed cases. Moreover, the performance of two rotorstator mechanisms was compared. The results indicate that the 3D gas holdup distribution in a mechanical flotation cell under different conditions can be estimated using ERT. Moreover, differences in the gas holdup distribution can be detected depending on which rotor-stator mechanism is in use.

2025, Near Surface Geophysics

ABSTRACTHigh‐resolution methods are required in the non‐destructive study of historical buildings, archaeological sites and cultural heritage structures in general. Ground‐penetrating radar (GPR) is widely used in such studies. However, radar images of archaeological sites and cultural heritage architecture tend to be unclear and are difficult to interpret. Knowledge of the antenna’s behaviour and the optimum expected resolution could help to interpret radar data and define a limit of the real resolution in field surveys. Laboratory tests could provide information about the optimum resolution for each specific antenna. The main goal of this study was to obtain experimental data under lab conditions and thus define the optimum resolution expected in radar surveys. This could then be considered as a limit in field surveys. All of the lab tests were performed using homogeneous media (water and sand) to avoid interference and clutter. As a result, simple images were obtained. The optimu...

2025, Spektra: Jurnal Fisika Dan Aplikasinya

A time-lapse microgravity survey has been carried out in the Kota Lama (Semarang, Indonesia) tourism area. The survey in question is to measure gravity at the same point repeatedly with a specific time interval, in this case, conducted in January 2019 and July 2019. Measuring gravity is carried out at as many as 75 points that are spread evenly at the survey location. The instrument used is a Scintrex CG5 type gravimeter and GPS to determine the latitude and the longitude of each measuring point. The measurement results after being corrected, namely the Apungan and the Appeal correction, obtained the observational gravity (g ob) in the January 2019 period showing that a minimum of 978118.44 mGal and a maximum gravity of 978118.88 mGal, while the minimum gravity measurement value in July 2019 showed a minimum of 978118.62 mGal and a maximum of 978118.88 mGal. Changes in the value (anomaly) gravity during the time interval, there are two possibilities, positive (0.02 to 0.29 mGal) and negative (-0.11 to-0.01 mGal). Both of these anomaly prices, if they are modeled, an anomaly source will be obtained, which is a positive anomaly caused by subsidence and a negative caused by changes in subsurface density related to dynamics (decrease or increase) of groundwater level.

2025

Tese de Doutoramento, Geologia, especialidade de Vulcanologia, 27 de outubro de 2016, Universidade dos Açores.O arquipélago de Cabo Verde é composto por 10 ilhas e vários ilhéus de origem vulcânica, sendo a ilha do Fogo a única onde se registaram erupções históricas. É neste contexto que o presente trabalho se debruça sobre a avaliação dos perigos vulcânicos e fenómenos associados nesta ilha, e nas respetivas implicações em termos de planeamento de emergência e ordenamento do território. Para se compreender melhor o vulcanismo da ilha do Fogo, fez-se o enquadramento geotectónico do arquipélago e da ilha, foi analisada bibliografia especializada e cartografadas as principais formas e produtos vulcânicos relacionados com a atividade mais recente. Foram também analisados e calculados os parâmetros morfométricos dos cones de escórias, comparando-se os resultados obtidos com os determinados para outras regiões vulcânicas. Paralelamente, fez-se a pesquisa, revisão e análise de todos os re...

2025, Geosciences Data Journal

Understanding regional sea level variations is crucial for assessing coastal vulnerability, with accurate sea level data playing a pivotal role. Utilizing historical sea level marigrams can enhance datasets, but current digitization techniques face challenges such as bends and skews in paper charts, impacting sea level values. This study explores often-overlooked issues during marigram digitization, focusing on the case study of Dún Laoghaire in Ireland (1925-1931).

2025, Remote Sensing

Ground-based ground-penetrating radar (GPR) has been applied successfully for decades in archaeological geophysics. However, there are sometimes severe problems arising in cases of rough terrain, permission to enter a site, or due to vegetation. Other issues may also make it impossible to use conventional ground-based GPR. Therefore, mounting the GPR antenna below a drone could be a potential alternative. Successful applications of drone-based GPR have already been reported, e.g., in the fields of geological mapping, glaciology, and UXO-detection. However, it is not clear whether faint archaeological remains can also be mapped using this approach. In the survey discussed below, we tested such a drone-based GPR setup at an archaeological site in Bavaria, where well-preserved Roman foundations at a shallow depth are known from previous geophysical surveys with magnetics and ground-based GPR. The aim was to evaluate the possibilities and problems arising with this new approach through a comparison with the afore-mentioned data, obtained in previous ground-based surveys of this site. The results show that under certain circumstances, the archaeological remains can be resolved while using a drone. However, the remains are much harder to detect with a lower degree of resolution and survey setup and acquisition time play a crucial role for a successful survey. Especially relevant are two factors: First, the correct choice of profile orientation, as there are strong reflections caused by near-surface features (like field boundaries) due to decoupling the antenna from the ground. Second, a very dry soil is mandatory, as otherwise too much signal is lost at the air-ground-interface. Considering these factors, drone-based GPR represents a valuable tool for modern archaeological geophysics.

2025

in 2003. Currently, he is a researcher and PhD student in the Department of Civil Engineering of the University of Minho, Guimar ã es, Portugal. His main research areas are the inspection and diagnosis of concrete and masonry structures... more

2025

The integration of geophysical data with direct hydrogeological measurements can provide a minimally invasive approach to characterize the subsurface at a variety of resolutions and over many spatial scales. The field of hydrogeophysics has attracted much attention during the last two decades. In this domain, the geophysical data inverted to geophysical models are interpreted in terms of the hydrogeology to serve as a basis for the definition of hydraulic models in the areas of interest. The hydraulic conductivity (K) value measured in a reference borehole has been combined with the electrical conductivity obtained from nearby Vertical Electrical Sounding data in the Kertajati confined aquifer. The resulting relation was interpreted with Dar Zarrouk parameters to infer the transmissivity variations at other vertical electrical sounding locations, where (K) values are unknown. The results indicate that the transmissivity values in the aquifer of interest vary from 553.935 to 14074 m/...

2025, Near Surface Geophysics

ABSTRACTUrban soils are subject to strong variations in environmental conditions, such as water flow, solute transport and heat budget. The INTERURBAN research project has been set up to investigate the dynamics of water and solutes at urban locations with particular attention to spatial heterogeneity, organic soil substance, and soil‐biological transformation processes in the unsaturated zone. The objectives of INTERURBAN also define the tasks for geophysics: the development of non‐invasive procedures to map water distribution, water dynamics and important structural parameters at small scales. This paper focuses on the development of a geophysical methodology as a tool for soil research. Approaches to adapting geophysical methods for particular objectives in the framework of the project have been successful. Soil moisture could be derived from ground‐penetrating radar (GPR) in combination with timedomain reflectometry (TDR), high‐resolution direct‐current geoelectrics (DC on a dm ...

2025, Geophysica

Frequency domain electromagnetic soundings were carried out at the Lupin gold mine and Ulu gold prospect in Northern Canada by the Geological Survey of Finland to investigate the lateral and vertical conditions of deep permafrost. The results indicate a deep seated electrical conductor in approximately half of the soundings. The detected conductor is interpreted as unfrozen and porous rock underneath the permafrost base saturated with saline groundwater. The mean depth of the permafrost base is 589 m and 476 m at the Lupin mine and Ulu prospect, respectively. The permafrost base, as deep as few hundreds of meters, can be detected using frequency domain electromagnetic soundings.

2025, GEOPHYSICS

The abundance and growth stages of bacteria in subsurface porous media affect the concentrations and distributions of charged species within the solid-solution interfaces. Therefore, spectral induced polarization (SIP) measurements can be used to monitor changes in bacterial biomass and growth stage. Our goal was to gain a better understanding of the SIP response of bacteria present in a porous material. Bacterial cell surfaces possess an electric double layer and therefore become polarized in an electric field. We performed SIP measurements over the frequency range of 0.1–1 kHz on cell suspensions alone and cell suspensions mixed with sand at four pore water conductivities. We used Zymomonas mobilis at four different cell densities (including the background). The quadrature conductivity spectra exhibited two peaks, one around 0.05–0.10 Hz and the other around 1–10 Hz. Because SIP measurements on bacterial suspensions are typically made at frequencies greater than 1 Hz, these peaks ...

2025

The study area which was located in Peninsular Malaysia comprised of residual meta-sedimentary soil derived Kenny Hill Formation. The dynamic soil properties of tropical meta-sediment residual soils were measured using non-destructive seismic method known as Multi-channel Analysis of Surface Wave (MASW) method. Twenty four geophones were located on ground in order to measure surface wave propagation. By inversion of dispersion curve, the shear wave velocity profile could be calculated and obtained. For most site investigations, other conventional method of field testing had been conducted such as drilling and Standard Penetration Test (SPT). This paper, however, attempts to obtain the comprehensively characteristics of dynamic soil properties of meta-sediment residual soils using the multi-channel analysis of surface wave (MASW) method and field soil tests. The comparison between the measurement results of all testing was conducted to evaluate the appropriateness of MASW results. The result shows that lateral variation and complexity of the meta-sediment residual soil stratification was found in the location. Thus, the soil dynamic properties at each layer can be properly estimated. A good agreement of soil bearing capacity was also found from MASW method compared to field soil tests.

2025, Engineering Geology

An optimal strategy for building realistic geological models must combine different geophysical techniques, each with its advantages and limitations. However, dealing with multiple geophysical datasets to derive a geological interpretation is not straightforward since geophysical parameters are not always functionally related. In this work, we propose an innovative approach consisting of using machine learning techniques to jointly interpret three geophysical datasets (a pseudo-3D resistivity model, a 3D velocity model, and 4 well-logs). These datasets, among others, were acquired to characterize the suitability of an evaporitic sequence for hosting a temporary storage facility of hazardous radioactive waste, which was planned in Villar de Cañas (Spain). Our strategy consisted of integrating both models in a single 3D bi-parametric grid that nested the velocity and resistivity values in each node. We then used a supervised learning algorithm to lithologically classify each node according to a training set based on the borehole data, which acts as ground truth. The training set is composed of classifiers that lithologically label resistivity-velocity pairs. However, the very shallow nodes lack classifiers due to the poor well-log coverage at the top part of the evaporitic sequence. To fill this gap, we computed an unsupervised cluster analysis that provided new classes to complete the training set. Finally, the supervised classification was applied, providing a new 3D lithology model that is far more consistent with the geology than the models derived from each parameter independently. The 3D model also revealed geological features previously unknown, notably the existence of an inactive fault. The proposed method can be applied to integrate and jointly interpret any kind of multidisciplinary datasets in a wide range of geoscientific problems, including natural resource exploration, geological storage, environmental monitoring, civil engineering practice, and hazard assessment.

2025

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2025

Исследования образуемых покрытий: элементного, фазового состава, технологических и эксплуатационных характеристик свидетельствует о превосходстве предлагаемых материалов по коэффициенту массопереноса, износостойкости, жаростойкости по сравнению с покрытиями из стандартных твердых сплавов (ВК8) при уменьшении себестоимости формирования 1 см покрытия до 5 раз. Воздействие электрического разряда в центральной области расплава приводит к формированию нанокристаллических зерен металла катода порядка 10 нм за счет быстрой кристаллизации расплава.

2025, IMEKO

An in-depth analysis of some areas in the Hellenistic, Roman and Byzantine city of Hierapolis of Phrygia has been carried out using high resolution geophysical methods integrated to the archaeological surveys in order to detect evidence of archaeological features buried under colluvial deposits and to acquire new data of some sectors of the urban area. In particular, three areas were investigated in the northern, central and southern sectors of the ancient city: i) the Northern Agora; ii) the Sanctuary of Apollo; iii) some insulae with houses in the central and southern sectors of the city. Geophysical data were collected in these areas of interest using different surveying methodologies, during different campaigns of activity of the Italian Archaeological Mission: Electrical Resistivity Tomography, Ground Penetrating Radar, Seismic Refraction Tomography, Magnetometry and GEM. All data collected were integrated in the digital archaeological map of Hierapolis, linked to a Geographic Information System (GIS), in order to contextualize the identified archaeological features in the ancient urban plan. In some cases, geophysical measurements were verified during subsequent archaeological excavations. In this paper some results related to the Temple of Apollo are presented.