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Archaeological prospection is continually expanding into new frontiers, examining increasingly large areas, diverse environmental contexts and varying site types. One area that has received only limited focus is historic battlefields. This paper presents results from large‐scale geophysical surveys (> 100 ha) at the Napoleonic battlefield of Waterloo (1815) in Belgium, using fluxgate magnetometry and frequency‐domain electromagnetic induction. Despite its international historical significance, professional archaeological research at the battlefield is still in its infancy. We demonstrate how important insights can be gained by using geophysical methods for identifying features and artefacts related to the battle and for developing an understanding of the various influences acting on the present landscape. The largest survey of its kind undertaken on a single battlefield site, this approach holds particular potential for battlefield archaeology, given the subtle and low‐density nature of the sought‐after targets and the extensive area of the site. Such an approach can mitigate (though not entirely resolve) challenges of resolution and scale associated with other methods of investigation. Using a representative range of examples from Waterloo, we consider successes and challenges in undertaking geophysical surveys on battlefield sites. An integrated approach that incorporates targeted sampling and other forms of ancillary data is emphasized for a more robust interpretation of noninvasive sensor data. [ABSTRACT FROM AUTHOR]

The editorial in "Frontiers in Earth Science" discusses the challenges faced by Latin America, such as tailing dam collapses, earthquake risks, and water resource management. Near-surface geophysics (NSGeo) is highlighted as a crucial tool for addressing these challenges, with a focus on practical, non-invasive solutions. The research papers in the special issue showcase how NSGeo methods are being applied to tackle natural disasters, pollution, and infrastructure risks in Latin America, emphasizing the technical advancements and societal impact of these techniques. The integration of advanced computational tools and field techniques with traditional geophysical methods enhances the effectiveness of NSGeo applications, making them essential for informed decision-making and sustainable development in the region. [Extracted from the article]

With the increase in groundwater exploration, underground mineral resource exploration, and non-destructive investigation of cultural relics, high-resolution earth electrical characteristic measurement has emerged as a mainstream technique owing to its advantageous non-destructive detection capability. To enhance the transmission power of the high-frequency transmitter in high-resolution multiple earth electrical characteristic measurement systems (MECS), this study proposes a high-frequency, high-current transmission technique based on adaptive impedance matching and implemented through the integration of resonant capacitors, a controllable reactor, high-frequency transformers, and corresponding control circuits. A high-current precisely controllable reactor with a 94% inductance variation range was designed and combined with resonant capacitors to reduce circuit impedance. Additionally, high-frequency transformers were employed to further increase the transmission voltage. A prototype was developed and tested, demonstrating an increase in transmission current at frequencies between 10 and 120 kHz with a peak active power of 200 W. Under the same transmission voltage, compared to the transmission circuit without impedance matching, the transmission current increased to a maximum of 16.7 times (average of 10.8 times), whereas compared to the transmission circuit using only traditional impedance matching, the transmission current increased by a maximum of 10.0 times (average of 4.2 times), effectively improving the exploration resolution. [ABSTRACT FROM AUTHOR]

We applied an interdisciplinary approach to analyze the late Quaternary activity of the Sava Fault in the Slovenian Southern Alps. The Sava Fault is an active strike-slip fault, and part of the Periadriatic Fault System that accommodated the convergence of Adria and Europe. It is one of the longest faults in the Southern Alps. Using high-resolution digital elevation models from lidar and photogrammetric surveys, we were able to overcome the challenges of assessing fault activity in a region with intense surface processes, dense vegetation, and relatively low fault slip rates. By integrating remote sensing analysis, geomorphological mapping, structural geological investigations, and near-surface geophysics (electrical resistivity tomography and ground penetrating radar), we were able to find subtle geomorphological indicators, detect near-surface deformation, and show distributed surface deformation and a complex fault pattern. Using optically stimulated luminescence dating, we tentatively estimated a slip rate of 1.8 ± 0.4 mm/a for the last 27 ka, which exceeds previous estimates and suggests temporal variability in fault behavior. Our study highlights the importance of modern high-resolution remote sensing techniques and interdisciplinary approaches in detecting tectonic deformation in relatively low-strain rate environments with intense surface processes. We show that slip rates can vary significantly depending on the studied time window. This is a critical piece of information since slip rates are a key input parameter for seismic hazard studies. [ABSTRACT FROM AUTHOR]

Air bubbles in the upper ocean are generated mainly by waves breaking at the air–sea interface. As such, after the waves break, entrained air bubbles evolve in the form of plumes in the turbulent flow, exchange gas with the surrounding water, and may eventually rise to the surface. To shed light on the short-term response of entrained bubbles in different stormy conditions and to assess the link between bubble plume penetration depth, mechanical and thermal forcings, and the air–sea transfer velocity of CO2 , a field experiment was conducted from an oceanographic research tower in the north Adriatic Sea. Air bubble plumes were observed using high-resolution echosounder data from an upward-looking 1000 kHz sonar. The backscatter signal strength was sampled at a high resolution, 0.5 s in time and 2.5 cm along the vertical direction. Time series profiles of the bubble plume depth were established using a variable threshold procedure applied to the backscatter strength. The data show the occurrence of bubbles organized into vertical plume-like structures, drawn downwards by wave-generated turbulence and other near-surface circulations, and reaching the seabed at 17 m depth under strong forcing. We verify that bubble plumes adapt rapidly to wind and wave conditions and have depths that scale approximately linearly with wind speed. Scaling with the wind–wave Reynolds number is also proposed to account for the sea-state severity in the plume depth prediction. Results show a correlation between measured bubble depths and theoretical air–sea CO2 transfer velocity parametrized with wind-only and wind/wave formulations. Further, our measurements corroborate previous results suggesting that the sinking of newly formed cold-water masses helps bring bubbles to greater depths than those reached in stable conditions for the water column. The temperature difference between air and sea seems sufficient for describing this intensification at the leading order of magnitude. The results presented in this study are relevant for air–sea interaction studies and pave the way for progress in CO2 gas exchange formulations. [ABSTRACT FROM AUTHOR]

We combined datasets from multiple research projects and remote sensing technologies to evaluate conservation conditions at La Fortaleza de Kuelap, a pre-Hispanic site in Peru that suffered significant damage under heavy seasonal rains in April 2022. To identify the causes of the collapse and where the monument is at further risk, we modeled surface hydrology using a DTM derived from drone LiDAR data, reconstructed a history of collapses, and calculated the volume of the most recent by fusing terrestrial LiDAR and photogrammetric datasets. In addition, we examined subsurface water accumulation with electrical resistivity, reconstructed the stratification of the monument with seismic refraction, and analyzed vegetation loss and ground moisture accumulation using satellite imagery. Our results point to rainwater infiltration as the most significant source of risk for La Fortaleza's perimeter walls. Combined with other adverse natural conditions and contemporary conservation interventions, this led to the 2022 collapse. Specialists need to consider these factors when tasked with conserving monuments located in comparable high-altitude perhumid environments. This integration of analytical results demonstrates how multi-scalar and multi-instrumental approaches provide comprehensive and timely assessments of conservation needs. [ABSTRACT FROM AUTHOR]

This study employs a multimethod approach to investigate the sediment distribution in two pocket beaches, Ramla Beach and Mellieha S Beach, in Malta. Both study sites were digitally reconstructed using unmanned aerial vehicle (UAV) photogrammetry. For each case, an ERT and a dense network of ambient seismic noise measurements processed through a horizontal-to-vertical spectral ratio (HVSR) technique were acquired. Electrical resistivity tomography (ERT) analysis enables the estimation of sediment thickness in each beach. HVSR analysis revealed peaks related to beach sediments overlying limestone rocks in both sites and also indicated a deeper stratigraphic contact in Mellieha S Beach. Based on ERT measurements, sediment thickness is calculated for each HVSR measurement. Interpolation of results allows for bedrock surface modelling in each case study, and when combined with digital terrain models (DTMs) derived from photogrammetric models, sediment volumes are estimated for each site. The geometry of this surface is analyzed from a geological perspective, showing structural control of sediment distribution due to a normal fault in Mellieha S Beach and stratigraphic control facilitated by a highly erodible surface in Ramla Beach. The results emphasize the importance of adopting a three-dimensional perspective in coastal studies for precise sediment volume characterization and a deeper understanding of pocket beach dynamics. This practical multimethod approach presented here offers valuable tools for future coastal research and effective coastal management, facilitating informed decision making amidst the growing vulnerability of coastal zones to climate change impacts. [ABSTRACT FROM AUTHOR]

This paper reviews methodological approaches in battlefield archaeology with a focus on sites of the early modern period, ca. 17th-19th century. The challenges associated with the prospection of these sites partially explains the relative lack of serious research in this area until the late 20th century. While acknowledging the foundational role of conventional metal detection in overcoming these difficulties, it is argued that other less widely deployed geophysical methods should be increasingly used as part of an integrated approach to studying battlefield landscapes. Targets of interest are reviewed alongside the geophysical properties that might enable their detection and a selection of case studies successfully deploying these approaches within battlefield archaeology and adjacent disciplines are considered. [ABSTRACT FROM AUTHOR]

Understanding the near-surface structure of the Earth requires accurate prediction of physical properties of the subsurface, such as velocity estimated from tomographic inversion of seismic refraction data. The predicted velocity values are often uncertain due to epistemic uncertainty in the inversion process (i.e., imperfectly known underlying physics) and aleatoric variability in the data (i.e., inherent noise in observations). Although seismic refraction is widely used in near-surface applications, the associated uncertainty is rarely quantified and presented alongside the inverted velocity tomograms. In this study, the effect of epistemic uncertainty due to local variability in the initial model and aleatoric variability due to first-arrival picking error on the velocity prediction uncertainty are investigated. A stochastic framework is implemented based on a statistical approach where multiple realizations of stochastically perturbed initial models and travel time picks are generated and the uncertainty in the predicted velocity models is quantified. The two sources of uncertainty are first studied independently and then the combined effect is investigated. The results show that both sources affect the posterior uncertainty, but the uncertainty in the initial model has a greater effect than picking error on the uncertainty of the posterior velocity model. In addition, joint analysis of both sources of uncertainty shows that the uncertainty in the inverted model depends on predicted velocity values, depths, velocity gradients and ray coverages. [ABSTRACT FROM AUTHOR]

Near-surface geophysics techniques have proven their reliability in various application fields, such as geotechnical engineering, resource exploration, and archaeological research. Their success in these contexts is closely related to data interpretation methods, which must be able to resolve shallow structures/bodies that are small and/or located at short distances from each other, thus preventing their identification and discrimination due to the overlapping effects generated by different sources. Here, we propose a new data inversion tool, based on a probabilistic Bayesian approach, which is able to scan near-surface magnetised structures. The developed algorithm allows selecting the mostlikely probability density function, associated with the most-likely magnetic susceptibility contrast distribution in the explored model space, by refining the discretisation of the anomalous areas, i.e. those areas corresponding to the highest susceptibility contrast. We validated the algorithm on synthetic magnetic data generated by anthropogeniclike bodies, and, then, inverted experimental magnetic measurements acquired at the archaeological site of Phaistos (Crete, Greece). In the latter case, the retrieved mostlikely model fits well with the remains found in the study area, and correctly identifies the proper magnetic susceptibility contrast, thickness, and depth of the Minoan wall top brought to light by the archaeological excavation. [ABSTRACT FROM AUTHOR]

Summary: Sedimentary units in alluvial fans may record gradual transport and deposition during multiple floods or sediment‐laden flows or, conversely, during few catastrophic events. While outcrops are a valuable source of direct information to constrain past geomorphic and hydrologic processes, such exposures are scarce, especially along aggrading rivers or those that have been subject to recent catastrophic sedimentation. In this context, near‐surface geophysical techniques can constrain the dimensions, internal architecture, composition, and petrophysical properties of different sedimentary units. We consider the Grimmbach alluvial fan in the cuesta landscape of southwestern Germany, which was heavily impacted by sediment and wood loads during a flash flood in 2016; published radiocarbon dates indicate that at least three floods similar to the one in 2016 may have occurred since the 17th century. To test whether and to which detail near‐surface geophysics might reveal the sedimentary legacy of these floods, we survey the Grimmbach alluvial fan using detailed topographic data and geophysical imaging based on electromagnetic induction, electrical resistivity tomography (ERT), and ground‐penetrating radar. Our geophysical results indicate former channel courses and two coarse bar deposits up to 3 m below the surface, which are comparable with the more extensive bar deposits of the 2016 flood. From the ERT models, we interpret coarse, up to 5 m thick, gravel lag overlying bedrock at a maximum depth of 10 m. Our geophysical results also highlight patches of finer materials derived from gradual sedimentation and soil development. Overall, our results show that the Grimmbach alluvial fan may have formed and reshaped during catastrophic flows, which likely caused channel avulsions. Our findings point to the need to reconsider flash flood and debris‐flow hazards in similar headwaters and fans of this seemingly quiescent cuesta landscape in southern Germany. [ABSTRACT FROM AUTHOR]

Groundwater discharge from high tropical islands can have a significant influence on the biochemistry of reef ecosystems. Recent studies have suggested that a portion of groundwater may underflow the reefs to be discharged, either through the reef flat or toward the periphery of the reef system. Understanding of this potential discharge process is limited by the characterization of subsurface reef structures in these environments. A geophysical method was used in this study to profile the reef surrounding the high volcanic island of Mo'orea, French Polynesia. Boat-towed continuous resistivity profiling (CRP) revealed electrically resistive features at about 10–15 m depth, ranging in width from 30 to 200 m. These features were repeatable in duplicate survey lines, but resolution was limited by current-channeling through the seawater column. Anomalous resistivity could represent the occurrence of freshened porewater confined within the reef, but a change in porosity due to secondary cementation cannot be ruled out. Groundwater-freshened reef porewater has been observed near-shore on Mo'orea and suggested elsewhere using similar geophysical surveys, but synthetic models conducted as part of this study demonstrate that CRP alone is insufficient to draw these conclusions. These CRP surveys suggest reefs surrounding high islands may harbor pathways for terrestrial groundwater flow, but invasive sampling is required to demonstrate the role of groundwater in terrestrial runoff. [ABSTRACT FROM AUTHOR]

Orphaned oil and gas wells represent an important environmental and economic development concern in areas where historical energy exploration and production activity pre-dated regulations on well abandonment documentation practices. From an economic development perspective, these wells pose a subsurface risk to infrastructure development, while the environmental impact of orphaned wells is largely associated with uncontrolled emissions of both fluids and gasses, most notably atmospheric methane. Often neglected in regulatory oversight, methane emissions from orphaned wells contribute to global greenhouse gas concentrations and without proper mitigation, these emissions contribute to and further exacerbate global climate change processes. An inherent challenge of remediation efforts targeting orphaned wells is the consistent observation that only a fraction of located and identified wells produce the majority of methane emissions, yet no methodology exists to effectively separate out heavy emitters without visiting and assessing each and every well. We demonstrate that emitting wells have certain defined characteristics largely pertaining to the presence and integrity of metal casing to the surface, which can be distinguished as an organized high intensity magnetic anomaly in low-altitude UAV-based aeromagnetic surveys. In this paper, we present a database of identified and ground-truthed wellsites correlated to their magnetic signatures and provide a roadmap to initial prioritization of wellsites for subsequent remediation activities that can be implemented in complex environments where other survey options are not feasible. In a regulatory environment where resources dedicated to wellsite remediation are limited, we propose implementing this methodology as a key element of a targeted approach to wellsite prioritization for subsequent remediation activity. [ABSTRACT FROM AUTHOR]

This article combining geophysics and archaeology aims to provide a more comprehensive characterization of the La Ruchelle valley located in the south of the Celtic site of La Peyrouse (Saint‐Félix‐de‐Villadeix, Dordogne, France) (occupied between the 3rd century BC and the 2nd century AD) through geological prospection (core sampling, geotechnical prospection and mechanical prospection) and near‐surface geophysics (electrical resistivity tomography). On this site, other studies have been carried out since the discovery of the site, such as magnetic prospecting and a hydrogeological study. Geophysical data coupled with geological prospection were used to understand the geology of the valley: (1) The bottom of the valley is filled with colluvium with a thickness of 6 m maximum; (2) part of the colluvium filling characterize by a very low resistivity is indeed archaeological remains; (3) three very distinct geological horizons have been detected—two of these horizons are characteristic of Campanian limestone (C6d and C6e), and the last consists of colluvium with a filling between 2 and 6 m in the centre of the valley, which is particularly thick. This last very thick formation is in fact filled with archaeological and prehistoric remains. [ABSTRACT FROM AUTHOR]

With the increase in groundwater exploration, underground mineral resource exploration, and non-destructive investigation of cultural relics, high-resolution earth electrical characteristic measurement has emerged as a mainstream technique owing to its advantageous non-destructive detection capability. To enhance the transmission power of the high-frequency transmitter in high-resolution multiple earth electrical characteristic measurement systems (MECS), this study proposes a high-frequency, high-current transmission technique based on adaptive impedance matching and implemented through the integration of resonant capacitors, a controllable reactor, high-frequency transformers, and corresponding control circuits. A high-current precisely controllable reactor with a 94% inductance variation range was designed and combined with resonant capacitors to reduce circuit impedance. Additionally, high-frequency transformers were employed to further increase the transmission voltage. A prototype was developed and tested, demonstrating an increase in transmission current at frequencies between 10 and 120 kHz with a peak active power of 200 W. Under the same transmission voltage, compared to the transmission circuit without impedance matching, the transmission current increased to a maximum of 16.7 times (average of 10.8 times), whereas compared to the transmission circuit using only traditional impedance matching, the transmission current increased by a maximum of 10.0 times (average of 4.2 times), effectively improving the exploration resolution.

The development of retrogressive thaw slumps (RTS) is known to be strongly influenced by relief-related parameters, permafrost characteristics, and climatic triggers. To deepen the understanding of RTS, this study examines the subsurface characteristics in the vicinity of an active thaw slump, located in the Richardson Mountains (Western Canadian Arctic). The investigations aim to identify relationships between the spatiotemporal slump development and the influence of subsurface structures. Information on these were gained by means of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR). The spatiotemporal development of the slump was revealed by high-resolution satellite imagery and unmanned aerial vehicle–based digital elevation models (DEMs). The analysis indicated an acceleration of slump expansion, especially since 2018. The comparison of the DEMs enabled the detailed balancing of erosion and accumulation within the slump area between August 2018 and August 2019. In addition, manual frost probing and GPR revealed a strong relationship between the active layer thickness, surface morphology, and hydrology. Detected furrows in permafrost table topography seem to affect the active layer hydrology and cause a canalization of runoff toward the slump. The three-dimensional ERT data revealed a partly unfrozen layer underlying a heterogeneous permafrost body. This may influence the local hydrology and affect the development of the RTS. The results highlight the complex relationships between slump development, subsurface structure, and hydrology and indicate a distinct research need for other RTSs.

For underground mining, efficient groundwater management is one of the critical mining economics components. The region of interest, known as Tharisa Mine, is situated on the western limb of the Bushveld Igneous Complex, which is home to South Africa's premier platinum-group metal resources. This work aimed to provide the findings from the investigation and imaging of the near-subsurface hydrogeological architecture in a shallow profile using stable isotopes of water (18O and 2H) and radioactive water isotopes (3H). Regarding isotope data, 18O varied from −3.5 to 1.5‰; 2H from −24 to 4.7‰; and 3H from 2.0 to 3.4 T.U. Utilizing combined geophysical techniques, the results were verified. Additionally, the geophysical methods, including seismic refraction tomography, multichannel analysis of surface waves, electrical resistivity tomography, and magnetics, helped identify the fluid's pathways and lineaments during migration to verify the isotope results. The groundwater inflow volumes into the open pit were initially determined by integrating the following findings: the delineation of fracture systems/zones and fluid migration pathways; mining activities enhance the storage and transmission ability of the aquifer; and the main sources of water in the mine include mixing of surface and deep water sources, recycling of water possibly via lineaments, and tailings dam seepages. [ABSTRACT FROM AUTHOR]

As a result of new discoveries, there is a greater opportunity for development and investment in the Al-Arraba EL-Madfuna region of Abydos, Sohag Governorate, Egypt, which benefits tourism and increases the national economy. The Coptic monastery, which was originally established by Apa Moses, the patriarch of the Coptic Church during the ancient Roman Empire, has vanished inside the current market on this site, along with numerous tombs. As a result, the primary goal of this work is to prospect on this site for these potential archaeological features. Ground magnetic and ground-penetration radar (GPR) surveys were employed for discovering these archaeological issues. This work was done in coordination with the Supreme Council of Antiquities. Ground magnetic and GPR surveys were implemented using the G-857 proton-precession magnetometer and GSSI SIR 4000 with a 200 MHz antenna. The data were processed and interpreted using Geosoft Oasis Montaj and REFLEXW v.5.8 software packages. The magnetic data were filtered to separate the shallower anomalies representing the archaeological remains from those of the deeper ones. Butterworth high pass filter, first vertical derivatives, analytical signal, and tilt derivative were employed to carry out the processing stages. The results were analyzed qualitatively and quantitatively to describe these anomalies and determine their locations, geometrical shapes, and depths. The source parameter imaging technique and 3D Euler deconvolution were used to calculate the depths. The analysis of magnetic maps shows that the study site is characterized by a number of anomalies that occur and have geometric squares and rectangle shapes with depths ranging from 0.7 m to ≈4 m. Some of these anomalies are related to potential archaeological objects. GPR findings reveal considerably scattered hyperbolas along several profiles, which may indicate the presence of potential buried objects. The integration of magnetic and GPR results showed that there is some consistency in the identification of the locations of the likely buried archaeological objects and their depths (0.7 to 3 m) for the majority of the discovered targets. The findings of this study suggest excavating at this location and relocating the market in order to protect the buried antiquities from being lost to be safeguarded as a tourist destination target. [ABSTRACT FROM AUTHOR]

Understanding how soil thickness and bedrock weathering vary across ridge and valley topography is needed to constrain the flowpaths of water and sediment production within a landscape. Here, we investigate saprolite and weathered bedrock properties across a ridge‐valley system in the Northern California Coast Ranges, USA, where topography varies with slope aspect such that north‐facing slopes have thicker soils and are more densely vegetated than south‐facing slopes. We use active source seismic refraction surveys to extend observations made in boreholes to the hillslope scale. Seismic velocity models across several ridges capture a high velocity gradient zone (from 1,000 to 2,500 m/s) located ∼4–13 m below ridgetops that coincides with transitions in material strength and chemical depletion observed in boreholes. Comparing this transition depth across multiple north‐ and south‐facing slopes, we find that the thickness of saprolite does not vary with slope aspects. Additionally, seismic survey lines perpendicular and parallel to bedding planes reveal weathering profiles that thicken upslope and taper downslope to channels. Using a rock physics model incorporating seismic velocity, we estimate the total porosity of the saprolite and find that inherited fractures contribute a substantial amount of pore space in the upper 6 m, and the lateral porosity structure varies strongly with hillslope position. The aspect‐independent weathering structure suggests that the contemporary critical zone structure at Rancho Venada is a legacy of past climate and vegetation conditions. Plain Language Summary: Below Earth's ground surface, porous space within weathered bedrock can store a significant amount of water, which is essential for ecosystems, particularly during the growing seasons. Collecting hydrologic data and core samplings from boreholes provides direct measurements about how bedrock is weathered and broken down toward the earth surface. Our study site is located in a series of ridges and valleys in Northern California, USA, where the local Mediterranean climate has distinctive dry summers and wet winters. This site represents a common topography along the east side of the Coast Ranges. In addition to synthesizing borehole and hydrologic data, we conduct complementary seismic refraction surveys to image material strength in the subsurface in 2D. These images can better capture the lateral variation of weathering zone thickness from channels to ridgetops. Seismic velocity derived from seismic refraction data shows an increase of material strength at the transition zone between saprolite and bedrock that agrees with borehole observations. Although vegetation density is much higher in the north‐ than the south‐facing hills, the depth to fresh bedrock is roughly the same. Our results also indicate that porous spaces in the weathered bedrock have the potential to store more water than annual precipitation. Key Points: A combination of geophysics and borehole measurements allows us to characterize lateral critical zone structure in a ridge‐channel systemDespite a strong aspect‐dependent contrast in soil thickness, saprolite thickness does not vary with slope aspectRock physics modeling using seismic velocity suggests that inherited bedrock fractures substantially contribute to saprolite total porosity [ABSTRACT FROM AUTHOR]

The information on geological structure as well as on the degree of contamination and geometrical parameters of a pollutant in oil-contaminated areas is necessary for risk assessment, planning of oil products recovery and territory remediation. Geophysical methods are actively used for solving such problems. The work considers the site on the Volga River bank, where soils are contaminated with petroleum products. The aim of the work is to delineate the distribution area of petroleum products. In order to achieve the goal, the set of near-surface geophysical methods (vertical electric sounding, seismic survey) and gas geochemistry were implemented. The results of a new approach to characterization of contaminated sites by RGB-data synthesis have been demonstrated as one of the ways of data interpretation. The method is based on the generalization of the available materials by optically mixing of the data of three spatially distributed characteristics presented in the form of three channels – red, green, and blue – for the purpose of localizing the lenses of gravity-mobile and immobilized oil products. According to the results of the qualitative interpretation of geophysical information, the authors have built a scheme with the proposed contour of oil products distribution in the studied territory. The proposed method can be used for the delineation of oil spills along with the sufficient information obtained by geophysical or other methods (at least three) at the stage of determining the spread of contamination for the sites. This approach can speed up the interpretation process, as such maps overlaying sets the color distribution of different petrophysical characteristics of the soils for the selected depth level, and also eases the task of determination of coordinates when correlating various anomalies, identified by different methods.

This research, examining the site of the HKP Forced-Labor Camp in Vilnius, Lithuania, located and better defined the characteristics and remaining features of the 1944 camp. There were four over-arching objectives for this research. First, to find the entrance into the principal hiding place where Jews interned in the camp took refuge just before the camp’s liquidation by the Nazis and their local collaborators. Next, find the location of the burial trench(es) where Jewish prisoners who were found in hiding were murdered and initially buried. Next, to find the mass-burial site where Jewish survivors reburied the remains from the trench(es). Lastly, to locate any other evidence related to the murder of Jews at the HKP 562 site. Ground-Penetrating Radar (GPR) found the principal hiding place in the basement of Building 2. Electrical Resistivity Tomography (ERT) discovered the two trenches where camp inhabitants who were shot on-site during liquidation were first buried. ERT also found the location of the mass grave that holds the reburied remains from the trenches. Bullet-scarred walls near the burial trenches indicate where the Jews were shot on-site. This research solved one of the thousands of unknowns about the Holocaust, using geoscience to uncover forgotten and hidden history. The materials and methodologies used in this research can be applied in uncovering this history at thousands of other Holocaust and genocide sites worldwide.

Arctic regions are highly impacted by the global temperature rising and its consequences and influences on the thermo-hydro processes and their feedbacks. Theses processes are especially not very well understood in the context of river–permafrost interactions and permafrost degradation. This paper focuses on the thermal characterization of a river–valley system in a continuous permafrost area (Syrdakh, Yakutia, Eastern Siberia) that is subject to intense thawing, with major consequences on water resources and quality. We investigated this Yakutian area through two transects crossing the river using classical tools such as in–situ temperature measurements, direct active layer thickness estimations, unscrewed aerial vehicle (UAV) imagery, heat transfer numerical experiments, Ground-Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT). Of these two transects, one was closely investigated with a long-term temperature time series from 2012 to 2018, while both of them were surveyed by geophysical and UAV data acquisition in 2017 and 2018. Thermodynamical numerical simulations were run based on the long-term temperature series and are in agreement with river thermal influence on permafrost and active layer extensions retrieved from GPR and ERT profiles. An electrical resistivity-temperature relationship highlights the predominant role of water in such a complicated system and paves the way to coupled thermo-hydro-geophysical modeling for understanding permafrost–river system evolution. [ABSTRACT FROM AUTHOR]

In drylands, groundwater is often the only perennial source of freshwater to sustain domestic water supplies and irrigation. Knowledge of the pathways and dynamics of groundwater discharge and recharge is, therefore, essential to inform sustainable and rational management of limited water resources. The lower valley of the Dallol Maouri in Niger represents a large fossil tributary (i.e. paleochannel) of the River Niger and drains groundwater regionally from the Iullemmeden Basin through coarse-grained Quaternary sediments. The objective of this paper is to quantify groundwater discharge within this paleochannel using piezometry and near-surface geophysics (TDEM: Time Domain Electromagnetics, MRS: Magnetic Resonance Sounding). TDEM and MRS experiments, conducted at 21 sites along 3 transects, show the thickness of the saturated Quaternary alluvium varies from 7 to 19 m with estimated effective porosities ranging from 18 to 38% and a hydraulic conductivity of 0.6–3 × 10–3 m/s. Dense piezometric surveys along drainage channel reveal hydraulic gradients of 0.2–0.3‰ that generate Darcy fluxes of 1000–2000 m3/day (dry season, i.e. minimum value). Paleochannel discharge, which currently provides baseflow to the River Niger, is the focus of local demand to increase access to water for drinking, livestock watering, and supplementary irrigation. [ABSTRACT FROM AUTHOR]

The Athenet network is the network of the Seismological Laboratory of the National and Kapodistrian University of Athens. We present the geophysical investigation that has been carried out at six seismological stations of the Athenet network for their site characterization. More specifically, at the location of each seismological station, four geophysical methods have been carried out: Seismic Refraction Tomography (SRT), Multichannel Analysis of Surface Waves (MASW), the Horizontal to Vertical Spectral Ratio (HVSR) technique, and Electrical Resistivity Tomography (ERT). The applied geophysical survey provided important information regarding the site characterization at the selected seismological stations, including key parameters such as the fundamental frequency fo, the shear-wave velocity VS, the average shear-wave velocity for the upper 30 m depth (VS30), the seismic bedrock depth, the soil type, and the subsurface geology. Moreover, selected elastic moduli (Poisson's ratio, shear, bulk, and Young moduli) have been calculated. The site characterization information contributes to the determination of the amplification factors for each site that can lead to more accurate calculation of Peak Ground Acceleration (PGA) or Peak Ground Velocity (PGV) and, therefore, trustworthy Probabilistic and Stochastic Seismic Hazard Assessments. The derived fundamental frequency for the seismological stations of VILL, LOUT, THAL, and EPID have been determined to be equal to 10.4, 2.7, 1.4, and 7.1 Hz and their amplification factors to be 1.9, 3.1, 1.7, and 2.6, respectively. For stations MDRA and ATAL, these parameters could not be determined. [ABSTRACT FROM AUTHOR]

Slope failures are an ongoing global threat leading to significant numbers of fatalities and infrastructure damage. Landslide impact on communities can be reduced using efficient early warning systems to plan mitigation measures and protect elements at risk. This manuscript presents an innovative geophysical approach to monitoring landslide dynamics, which combines electrical resistivity tomography (ERT) and low-frequency distributed acoustic sensing (DAS), and was deployed on a slope representative of many landslides in clay rich lowland slopes. ERT is used to create detailed, dynamic moisture maps that highlight zones of moisture accumulation leading to slope instability. The link between ERT derived soil moisture and the subsequent initiation of slope deformation is confirmed by low-frequency DAS measurements, which were collocated with the ERT measurements and provide changes in strain at unprecedented spatiotemporal resolution. Auxiliary hydrological and slope displacement data support the geophysical interpretation. By revealing critical zones prone to failure, this combined ERT and DAS monitoring approach sheds new light on landslide mechanisms. This study demonstrates the advantage of including subsurface geophysical monitoring techniques to improve landslide early warning approaches, and highlights the importance of relying on observations from different sources to build effective landslide risk management strategies.

Low frequency loop-loop electromagnetic induction (EMI) is a widely-used geophysical measurement method to rapidly measure in situ the apparent electrical conductivity (ECa) of variably-saturated soils. Here, we couple Bayesian inversion of a quasi-two-dimensional electromagnetic (EM) model with image compression via the discrete cosine transform (DCT) for subsurface electrical conductivity (EC) imaging. The subsurface EC distributions are obtained from multi-configuration EMI data measured with a CMD-Explorer sensor along two transects in the Chicken Creek catchment (Brandenburg, Germany). Dipole-dipole electrical resistivity tomography (ERT) data are used to benchmark the inferred EC fields of both transects. We are especially concerned with the impact of the DCT truncation method on the accuracy and reliability of the inversely-estimated EC images. We contrast the results of two different truncation approaches for model parametrization. The first scenario considers an arbitrary selection of the dominant DCT coefficients and their prior distributions (a commonly-used approach), while the second methodology benefits from geostatistical simulation of the EMI data pseudosection. This study demonstrates that DCT truncation based on geostatistical simulations facilitates a robust selection of the dominant DCT coefficients and their prior ranges, resulting in more accurate subsurface EC imaging from multi-configuration EMI data. Results based on geostatistical prior modeling present an excellent agreement between the EMI- and ERT-derived EC fields of the Chicken Creek catchment.

This research, examining the site of the HKP Forced-Labor Camp in Vilnius, Lithuania, located and better defined the characteristics and remaining features of the 1944 camp. There were four over-arching objectives for this research. First, to find the entrance into the principal hiding place where Jews interned in the camp took refuge just before the camp's liquidation by the Nazis and their local collaborators. Next, find the location of the burial trench(es) where Jewish prisoners who were found in hiding were murdered and initially buried. Next, to find the mass-burial site where Jewish survivors reburied the remains from the trench(es). Lastly, to locate any other evidence related to the murder of Jews at the HKP 562 site. Ground-Penetrating Radar (GPR) found the principal hiding place in the basement of Building 2. Electrical Resistivity Tomography (ERT) discovered the two trenches where camp inhabitants who were shot on-site during liquidation were first buried. ERT also found the location of the mass grave that holds the reburied remains from the trenches. Bullet-scarred walls near the burial trenches indicate where the Jews were shot on-site. This research solved one of the thousands of unknowns about the Holocaust, using geoscience to uncover forgotten and hidden history. The materials and methodologies used in this research can be applied in uncovering this history at thousands of other Holocaust and genocide sites worldwide. [ABSTRACT FROM AUTHOR]

The aims of agricultural land management change continuously, reflecting shifts in wider societal priorities. Currently, these include addressing the climate crisis, promoting environmental sustainability, and supporting the livelihoods of rural communities while ensuring food security. Working toward these aims requires information on the character of agricultural land and how dynamic processes influence it. Remote and near-surface sensing data are important sources of information on the characteristics of soils, plants, water, topography, and related processes. Sensing data are collected, analysed, and used in decision-making by specialists in multiple domains connected to land management. While progress has been made to connect the use of sensing data across agricultural and environmental applications under the umbrella of integrated sustainable land management, archaeological and heritage uses of these data remain largely disconnected. This creates barriers to accounting for the impacts of past human activities on contemporary agricultural landscapes through the alteration of soils, topography, and plant communities. In parallel, it hinders the creation of knowledge about the archaeological features which form an essential part of the heritage of agricultural landscapes. The ipaast-czo project explores the potential of a coordinated approach across all these domains, which would reduce these barriers and provide benefits by better integrating information generated using sensing. To do so, both conceptual and practical barriers to developing shared practices and how these might be overcome were considered. In this study, a conceptual framework designed to create a shared understanding of how agricultural landscapes work and enable collaboration around their management was proposed. This framework treats present-day rural agricultural landscapes as Critical Zones: complex entities shaped by long-term human–environment interactions including contemporary farming. Practitioners in precision agriculture and archaeological remote and near-surface sensing, as well as users of these data, were engaged using workshops and interviews. The relationships between practitioners' objectives, data requirements for their applications, and their perceptions of the benefits and disadvantages of changing working practices were interrogated. The conceptual framework and assessment of practical benefits and challenges emerging from this work provide a foundation for leveraging shared sensing data and methods for long-term integrated sustainable land management. [ABSTRACT FROM AUTHOR]

The development of retrogressive thaw slumps (RTS) is known to be strongly influenced by relief-related parameters, permafrost characteristics, and climatic triggers. To deepen the understanding of RTS, this study examines the subsurface characteristics in the vicinity of an active thaw slump, located in the Richardson Mountains (Western Canadian Arctic). The investigations aim to identify relationships between the spatiotemporal slump development and the influence of subsurface structures. Information on these were gained by means of electrical resistivity tomography (ERT) and ground-penetrating radar (GPR). The spatiotemporal development of the slump was revealed by high-resolution satellite imagery and unmanned aerial vehicle–based digital elevation models (DEMs). The analysis indicated an acceleration of slump expansion, especially since 2018. The comparison of the DEMs enabled the detailed balancing of erosion and accumulation within the slump area between August 2018 and August 2019. In addition, manual frost probing and GPR revealed a strong relationship between the active layer thickness, surface morphology, and hydrology. Detected furrows in permafrost table topography seem to affect the active layer hydrology and cause a canalization of runoff toward the slump. The three-dimensional ERT data revealed a partly unfrozen layer underlying a heterogeneous permafrost body. This may influence the local hydrology and affect the development of the RTS. The results highlight the complex relationships between slump development, subsurface structure, and hydrology and indicate a distinct research need for other RTSs. [ABSTRACT FROM AUTHOR]

This study employs a multimethod approach to investigate the sediment distribution in two pocket beaches, Ramla Beach and Mellieha S Beach, in Malta. Both study sites were digitally reconstructed using unmanned aerial vehicle (UAV) photogrammetry. For each case, an ERT and a dense network of ambient seismic noise measurements processed through a horizontal-to-vertical spectral ratio (HVSR) technique were acquired. Electrical resistivity tomography (ERT) analysis enables the estimation of sediment thickness in each beach. HVSR analysis revealed peaks related to beach sediments overlying limestone rocks in both sites and also indicated a deeper stratigraphic contact in Mellieha S Beach. Based on ERT measurements, sediment thickness is calculated for each HVSR measurement. Interpolation of results allows for bedrock surface modelling in each case study, and when combined with digital terrain models (DTMs) derived from photogrammetric models, sediment volumes are estimated for each site. The geometry of this surface is analyzed from a geological perspective, showing structural control of sediment distribution due to a normal fault in Mellieha S Beach and stratigraphic control facilitated by a highly erodible surface in Ramla Beach. The results emphasize the importance of adopting a three-dimensional perspective in coastal studies for precise sediment volume characterization and a deeper understanding of pocket beach dynamics. This practical multimethod approach presented here offers valuable tools for future coastal research and effective coastal management, facilitating informed decision making amidst the growing vulnerability of coastal zones to climate change impacts.

Groundwater discharge from high tropical islands can have a significant influence on the biochemistry of reef ecosystems. Recent studies have suggested that a portion of groundwater may underflow the reefs to be discharged, either through the reef flat or toward the periphery of the reef system. Understanding of this potential discharge process is limited by the characterization of subsurface reef structures in these environments. A geophysical method was used in this study to profile the reef surrounding the high volcanic island of Mo’orea, French Polynesia. Boat-towed continuous resistivity profiling (CRP) revealed electrically resistive features at about 10–15 m depth, ranging in width from 30 to 200 m. These features were repeatable in duplicate survey lines, but resolution was limited by current-channeling through the seawater column. Anomalous resistivity could represent the occurrence of freshened porewater confined within the reef, but a change in porosity due to secondary cementation cannot be ruled out. Groundwater-freshened reef porewater has been observed near-shore on Mo’orea and suggested elsewhere using similar geophysical surveys, but synthetic models conducted as part of this study demonstrate that CRP alone is insufficient to draw these conclusions. These CRP surveys suggest reefs surrounding high islands may harbor pathways for terrestrial groundwater flow, but invasive sampling is required to demonstrate the role of groundwater in terrestrial runoff.

Orphaned oil and gas wells represent an important environmental and economic development concern in areas where historical energy exploration and production activity pre-dated regulations on well abandonment documentation practices. From an economic development perspective, these wells pose a subsurface risk to infrastructure development, while the environmental impact of orphaned wells is largely associated with uncontrolled emissions of both fluids and gasses, most notably atmospheric methane. Often neglected in regulatory oversight, methane emissions from orphaned wells contribute to global greenhouse gas concentrations and without proper mitigation, these emissions contribute to and further exacerbate global climate change processes. An inherent challenge of remediation efforts targeting orphaned wells is the consistent observation that only a fraction of located and identified wells produce the majority of methane emissions, yet no methodology exists to effectively separate out heavy emitters without visiting and assessing each and every well. We demonstrate that emitting wells have certain defined characteristics largely pertaining to the presence and integrity of metal casing to the surface, which can be distinguished as an organized high intensity magnetic anomaly in low-altitude UAV-based aeromagnetic surveys. In this paper, we present a database of identified and ground-truthed wellsites correlated to their magnetic signatures and provide a roadmap to initial prioritization of wellsites for subsequent remediation activities that can be implemented in complex environments where other survey options are not feasible. In a regulatory environment where resources dedicated to wellsite remediation are limited, we propose implementing this methodology as a key element of a targeted approach to wellsite prioritization for subsequent remediation activity.

Remote and near surface sensing data are widely used in archaeology and heritage management for feature discovery, change detection and monitoring, as an input to predictive modelling, and in the planning process. While global and regional datasets are widely used for some purposes, data are regularly acquired specifically for archaeological projects because of the very high spatial resolution required for feature detection and assessments of archaeological significance and the need for data on subsurface features. The sensing data collected for archaeology cover limited areas and only a few types of sensors, known to produce data efficiently, are regularly employed. Precision agriculture is beginning to produce large quantities of varied sensing data across extensive landscape areas. This situation creates an opportunity to adapt and reuse precision agricultural data for archaeology and heritage work, extending covering and enhancing our understanding of archaeology in contemporary agricultural landscapes. Equally, there is potential for coordinated data collection, collecting data once for multiple applications, and to add value through analyses which bring together perspectives from multiple related domains to model long-term processes in anthropogenic soil systems. This article provides a high-level overview of policy and technological developments which create the potential for sensing data reuse, coordinated data collection, and collaborative analyses across archaeological, agricultural, and agri-environmental applications while underscoring the structural barriers which, at present, constrain this potential. It highlights examples where the development of interoperable data and workflows can promote tighter integration of archaeology and cultural heritage management with sustainable agricultural land management and support integrated decision making.

Passive surface-wave methods have been given increased attention from the near-surface geophysics community because of their advantages of being low-cost and environment-friendly, especially in urban environments. The traffic noise sources, however, are not randomly distributed in time and space in densely populated urban areas. Stacking of cross-correlations is unable to effectively attenuate the azimuthal effects due to noise source distribution, resulting in overestimated surface-wave phase velocities. To solve this problem, we proposed a beamforming-based segment (i.e., time window) selection scheme that applies a beamforming technique with a pseudo-linear array to capture the noise segments coming from the sources in the stationary-phase zone. The azimuthal range of in-line noise sources is determined by the Fresnel angle calculated from the measured shortest wavelength. The cross-correlation is applied to these selected stationary-phase segments. The causal parts of cross-correlations are stacked to obtain the final virtual shot gather, since the single directional in-line noise sources are known through beamforming analysis. We used a synthetic test and two real-world examples of traffic-induced noise data acquired in urban environments to verify the feasibility of the proposed scheme. Results demonstrated that the proposed selection scheme can obtain virtual shot gathers with higher signal-to-noise ratio, higher-resolution dispersion energy, and accurate phase velocities, which provides an alternative tool for the applications of using passive surface-wave methods in urban environments, especially for the case of changes in distribution of noise sources in a short time. [ABSTRACT FROM AUTHOR]

Electrical Resistivity Tomography (ERT) is a robust and well-consolidated method largely applied in near-surface geophysics. Nevertheless, the mapping of the spatial resistivity patterns of the subsurface at a depth greater than 1 km was performed in just a few cases by the ERT method, called deep ERT (DERT). Since, in many cases, the term DERT was adopted with ambiguity for geoelectrical explorations varying in depth within a range of 0–500 m, the main goal of this review is to clearly define the DERT method, identifying a threshold value in the investigation depth. The study focuses both on the purely methodological aspects (e.g., geoelectrical data processing in low noise-to-signal ratio conditions; tomographic algorithms for data inversion) and on the technological features (e.g., sensor layouts, multi-array systems), envisaging the future directions of the research activity, especially that based on machine learning, for improving the geoelectrical data processing and interpretation. The results of the more significant papers published on this topic in the last 20 years are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Non-invasive subsurface imaging using full waveform inversion (FWI) has the potential to fundamentally change near-surface (<30 m) site characterization by enabling the recovery of high-resolution (metre-scale) 2-D/3-D maps of subsurface elastic material properties. Yet, FWI results are quite sensitive to their starting model due to their dependence on local-search optimization techniques and inversion non-uniqueness. Starting model dependence is particularly problematic for near-surface FWI due to the complexity of the recorded seismic wavefield (e.g. dominant surface waves intermixed with body waves) and the potential for significant spatial variability over short distances. In response, convolutional neural networks (CNNs) are investigated as a potential tool for developing starting models for near-surface 2-D elastic FWI. Specifically, 100 000 subsurface models were generated to be representative of a classic near-surface geophysics problem; namely, imaging a two-layer, undulating, soil-over-bedrock interface. A CNN has been developed from these synthetic models that is capable of transforming an experimental wavefield acquired using a seismic source located at the centre of a linear array of 24 closely spaced surface sensors directly into a robust starting model for FWI. The CNN approach was able to produce 2-D starting models with seismic image misfits that were significantly less than the misfits from other common starting model approaches, and in many cases even less than the misfits obtained by FWI with inferior starting models. The ability of the CNN to generalize outside its two-layered training set was assessed using a more complex, three-layered, soil-over-bedrock formation. While the predictive ability of the CNN was slightly reduced for this more complex case, it was still able to achieve seismic image and waveform misfits that were comparable to other commonly used starting models, despite not being trained on any three-layered models. As such, CNNs show great potential as tools for rapidly developing robust, site-specific starting models for near-surface elastic FWI. [ABSTRACT FROM AUTHOR]

Of the six papers included in this section, only two were primarily focused on I V i SB I S i sb measurements and both focused on the use of surface wave methods to generate in situ I V i SB I S i sb models (Hobiger et al. [17]; Stephenson et al. [39]). Factors to be considered for the best possible estimates of both active- and passive-source surface-wave dispersion data are illustrated in detail. Keywords: COSMOS guidelines; Best-practices; Seismic site characterization; Earthquake site effects EN COSMOS guidelines Best-practices Seismic site characterization Earthquake site effects 557 566 10 08/24/22 20220801 NES 220801 Article Highlights 1. [Extracted from the article]

Seismic attenuation and the associated quality factor (Q) have long been studied in various sub-disciplines of seismology, ranging from observational and engineering seismology to near-surface geophysics and soil/rock dynamics with particular emphasis on geotechnical earthquake engineering and engineering seismology. Within the broader framework of seismic site characterization, various experimental techniques have been adopted over the years to measure the near-surface shear-wave quality factor (QS). Common methods include active- and passive-source recording techniques performed at the free surface of soil deposits and within boreholes, as well as laboratory tests. This paper intends to provide an in-depth review of what Q is and, in particular, how QS is estimated in the current practice. After motivating the importance of this parameter in seismology, we proceed by recalling various theoretical definitions of Q and its measurement through laboratory tests, considering various deformation modes, most notably QP and QS. We next provide a review of the literature on QS estimation methods that use data from surface and borehole sensor recordings. We distinguish between active- and passive-source approaches, along with their pros and cons, as well as the state-of-the-practice and state-of-the-art. Finally, we summarize the phenomena associated with the high-frequency shear-wave attenuation factor (kappa) and its relation to Q, as well as other lesser-known attenuation parameters. [ABSTRACT FROM AUTHOR]

Weathering and erosion processes are crucial to Critical Zone (CZ) evolution, landscape formation and availability of natural resources. Although many of these processes take place in the deep CZ (∼10–100 m), direct information about its architecture remain scarce. Near‐surface geophysics offers a cost‐effective and minimally intrusive alternative to drilling that provides information about the physical properties of the CZ. We propose a novel workflow combining seismic measurements, petrophysical modelling and geostatistical analysis to characterize the architecture of the deep CZ at the catchment scale, on the volcanic tropical island of Basse‐Terre (Guadeloupe, France). With this original workflow, we are for the first time able to jointly produce maps of the water table and the weathering front across an entire catchment, by means of a single geophysical method. This integrated view of the CZ highlights complex weathering patterns that call for going beyond "simple" hillslope CZ models. Plain Language Summary: Infiltration of rainwater into the subsurface chemically alters and breaks down rock at depth, thus creating porous space able to store life‐sustaining water for overlying ecosystems. Information about the structure and the water content of this invisible compartment is difficult to obtain. Here we use minimally invasive geophysical techniques to image this subsurface porous layer, and map the depth of the weathered zone and the water table. We applied this approach across forested slopes of Basse‐Terre island (Guadeloupe, France), which is representative of volcanic tropical landscapes with strong weathering and erosion activity. We use petrophysical relationships to convert our geophysical measurements into estimates of porosity and water saturation. We then apply spatial interpolation techniques to extend our local estimates across the entire watershed. Our novel approach provides unique insights on both the physical structure and water content of the subsurface at such a scale. Key Points: A novel combination of geophysics, petrophysics and geostatistics is used to characterize the architecture of the deep critical zoneWe produce maps of the water table and the weathering front across an entire catchment, by means of a single geophysical methodWe highlight spatial weathering patterns that call for going beyond "simple" hillslope representations of the Critical Zone (CZ) [ABSTRACT FROM AUTHOR]

The Carboniferous Joggins Formation is known for its complete succession of fossil-rich, coal-bearing strata, deposited in a fluvial meanderbelt depositional setting. Hence, the Joggins Formation outcrop is an excellent analogue for studying the 2D geological complexities associated with meanderbelt systems. In this research, a conventional ground-penetrating radar system was tested with the intent of imaging near-surface, dipping, strata of the Joggins Formation (potentially with subsequent repeats as annual erosion provides new visual calibrations). The survey was unsuccessful in its primary goal, and for future reference we document the reasons here. However, the overlying near-surface angular unconformity was successfully imaged enabling mapping of the approximately 8 m of overlying glacial till. A successful outcome would have allowed observations from the 2D outcrop to be extended into 3D space and perhaps lead to an increased understanding of the small (e.g., bedform baffles and barriers) and large (e.g., channel bodies) scale architectural elements, meanderbelt geometry, and aspect ratios. The study comprises a 42-line, 3.46 km ground-penetrating radar survey using a Sensors and Software pulseEKKO Pro SmartCart system. It was combined with a real-time kinematic differential global positioning system for the georeferencing of survey lines. The 50 MHz antenna frequency, with a 1 m separation, was chosen to maximize the depth of penetration, while still maintaining a reasonable resolution. The results show that many of the lines are contaminated with diffraction hyperbolae, possibly caused from buried objects near or under the survey lines or surface objects near the survey lines. A total of thirteen unique radar reflectors are described and interpreted from this work. The thick clay-rich soil overlying the Joggins Formation probably contributed to significant signal attenuation and the nature of the Carboniferous strata (dip of the beds, pinching and swelling of the beds, bed thickness, etc.) also contributed to imaging difficulties.

Arctic regions are highly impacted by the global temperature rising and its consequences and influences on the thermo-hydro processes and their feedbacks. Theses processes are especially not very well understood in the context of river–permafrost interactions and permafrost degradation. This paper focuses on the thermal characterization of a river–valley system in a continuous permafrost area (Syrdakh, Yakutia, Eastern Siberia) that is subject to intense thawing, with major consequences on water resources and quality. We investigated this Yakutian area through two transects crossing the river using classical tools such as in–situ temperature measurements, direct active layer thickness estimations, unscrewed aerial vehicle (UAV) imagery, heat transfer numerical experiments, Ground-Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT). Of these two transects, one was closely investigated with a long-term temperature time series from 2012 to 2018, while both of them were surveyed by geophysical and UAV data acquisition in 2017 and 2018. Thermodynamical numerical simulations were run based on the long-term temperature series and are in agreement with river thermal influence on permafrost and active layer extensions retrieved from GPR and ERT profiles. An electrical resistivity-temperature relationship highlights the predominant role of water in such a complicated system and paves the way to coupled thermo-hydro-geophysical modeling for understanding permafrost–river system evolution.

In the northern part of Sumatra Island, Indonesia, the Great Sumatran Fault, which can cause an earthquake, was divided into two segments: the Aceh and Seulimeum. An effort to reduce the risk is mapping the fault area, especially in the region that does not clearly show the sign on the surface, e.g., in the Lamtamot area, Indonesia. Electrical resistivity is widely used to study shallow structures, but the method requires more time when applied in a large area. This research explores the potential of an extremely low frequency (very low frequency-electromagnetic; VLF-EM) method to investigate the shallow fault of the Seulimeum segment. Here, the VLF-EM is compared with other geophysical methods such as resistivity and magnetic methods. For comprehensive results, the geomorphic observation that was conducted covered outcrops of the fault and trenching sites in the geophysical study for validating the model. A similar pattern of the VLFEM and electrical resistivity data has been shown in a two-dimensional profile using data processing. The fault structure can be mapped at a distance of 20-24 m from the profile measurement, which is demonstrated by the low current density associated with the conductive zone from the VLF-EM, and low resistive anomaly in electrical resistivity. The fault can also be confirmed via magnetic intensity, which significantly increases at the same distance (20-25 m) of the VLF-EM and electrical resistivity. The geomorphic observation shows outcrops of fault activity, such as fault scarp, fractures, and faults, in the same direction as the Seulimeum segment, while scrap extends in the northwest direction up to ~20 m around the geophysical surveys. As revealed by the results, the VLF-EM method combined with other geophysical surveys and geomorphic observation can be used as a technique to image the fault that shows the shallow structure of the Seulimeum fault at 20-32 m along the profile. [ABSTRACT FROM AUTHOR]

Shallow-seismic full-waveform inversion (FWI) is becoming increasingly popular for the reconstruction of the shallow-subsurface model in near-surface geophysics. Because Rayleigh waves dominate the vertical component of the shallow-seismic recording, FWI mainly fits Rayleigh waves in the observed data, while the utilization and fitting of P waves in the data are usually overlooked. The appropriate use of the body-wave signal in shallow-seismic FWI remains a problem. We propose herein a wavefield-separated full-waveform inversion (WSFWI) method to make better use of the P-wave signal in the shallow-seismic data. The WSFWI method mainly contains two steps: (1) separating the P wave from the observed data and applying an acoustic FWI to it for the reconstruction of the P-wave velocity model, and (2) fixing the P-wave velocity model and applying an elastic FWI to the entire recording for the reconstruction the S-wave velocity model. We show that Rayleigh and P waves are sensitive towards different areas of the model, and therefore, WSFWI can better utilize the sensitivity kernel of P waves to improve the accuracy of the reconstructed P-wave velocity model. A synthetic example shows that WSFWI outperforms the FWI that uses the whole recording simultaneously, especially in the reconstruction of the P-wave velocity model. It also proves that WSFWI is able to avoid (mitigate) crosstalk imposed from the S-wave velocity to the P-wave velocity models. We apply both the conventional FWI and WSFWI to a field data set acquired in Olathe, Kansas, USA. The field example shows that the S-wave velocity model can be reconstructed with high robustness in both the FWI and WSFWI results. Both the conventional FWI and WSFWI nicely fitted the observed Rayleigh wave, while WSFWI also fitted the P waves in the observed data and reconstructed the P-wave velocity model with relatively higher reliability. [ABSTRACT FROM AUTHOR]

Sustainable agriculture management typically requires detailed characterization of physical, chemical, and biological aspects of soil properties. These properties are essential for agriculture and should be determined before any decision for crop type selection and cultivation practices. Moreover, the implementation of soil characterization at the beginning could avoid unsustainable soil management that might lead to gradual soil degradation. This is the only way to develop appropriate agricultural practices that will ensure the necessary soil treatment in an accurate and targeted way. Remote sensing and geophysical surveys have great opportunities to characterize agronomic soil attributes non-invasively and efficiently from point to field scale. Remote sensing can provide information about the soil surface (or even a few centimeters below), while near-surface geophysics can characterize the subsoil. Results from the methods mentioned above can be used as an input model for soil and/or soil/water interaction modeling. The soil modeling can offer a better explanation of complex physicochemical processes in the vadose zone. Considering their potential to support sustainable agriculture in the future, this paper aims to explore different methods and approaches, such as the applications of remote sensing, geophysics, and modeling in soil studies. [ABSTRACT FROM AUTHOR]

Pointing to the Integrated, Coordinated, Open, Networked Findability, Accessibility, Interoperability, and Reusability (ICON‐FAIR) principles, we have determined several opportunities for implementation within the realm of near‐surface geophysics (NSG), representing a broad range of data acquisition and processing technologies. Our work explores the multifaceted community‐driven nature of NSG and, by applying ICON‐FAIR principles, we identify three key strategic objectives: (i) the development of an approach to integrating NSG into other geoscience data collection projects, (ii) the creation of coordinated and open standardized NSG data, and (iii) the networking of post‐secondary institutions to foster an equipment sharing consortium. The precedence within the geoscientific community demonstrates that there are significant opportunities for advancing interdisciplinary applications of NSG through the implementation of structural change within the ICON‐FAIR framework. Key Points: Near‐surface geophysics is a critical component to better understanding earth systems processesStandardizing practices and file‐formats will result in more cohesive and efficient science and knowledge productionInter‐institutional networking will facilitate equipment mobilization, and information sharing [ABSTRACT FROM AUTHOR]