Impedance Tomography Research Articles

Geophysical Investigation of Buried Small Fault Beneath Western Mount Malabar Using Electrical Resistivity Tomography in The Great Bandung Basin Rim

This article presents the discovery of a buried fault beneath the soil layers in the Mt Malabar area, which complements the information on suspected faults on the previous geological maps. Using an Electrical Resistivity Tomography (ERT) method, this study aims to delineate the layer discontinuity as a fault and describe the subsurface geology. This study employed a 1400 m long ERT line as the main line to identify buried fault traces, while each ERT line has an 800 m long installation across the main ERT line to obtain the direction of the minor fault. The investigation found a minor fault in the rock layer at a high resistivity layer, approximately 160 m below the surface. The identified rock units are believed to include sandy clay in the upper layer, followed by tuff, sandstone, and basalt lava in the lower layer because its resistivity value is above 250 Ohm.m. The 3D ERT model interpreted a minor buried fault as a weak zone beneath the soil and obtained the fault strike at approximately N 310°E and dipping 66°. Furthermore, these results are strengthened by the geological map, which confirms that ERT L-1 and ERT L-3 profiles coincide with a suspected fault in the Qmt rock unit area.

Spring-water temperature suggests widespread occurrence of Alpine permafrost in pseudo-relict rock glaciers

Abstract. Runoff originating from ground ice contained in rock glaciers represents a significant water supply for lowlands. Pseudo-relict rock glaciers contain patchy permafrost but appear to be relict, and therefore they can be misinterpreted when using standard classification approaches. The permafrost content, spatial distribution and frequency of this type of rock glacier are poorly known. Therefore, identifying pseudo-relict rock glaciers that might still contain permafrost, and potentially ice, is crucial for understanding their hydrological role in a climate change context. This work analyses rock–glacier spring-water temperature in a 795 km2 catchment in the eastern Italian Alps to understand how many rock glaciers classified as relict could have spring-water temperatures comparable to active or transitional rock glaciers as possible evidence of their pseudo-relict nature. Spring-water temperature, often auxiliary to other approaches for specific sites, was used for a preliminary estimate of the permafrost presence in 50 rock glaciers classified as relict. In addition, we present electrical resistivity tomography (ERT) results on two relict rock glaciers with opposing spring-water temperature and surface characteristics to constrain spring-water temperature results at the local scale. The results show that about 50 % of the rock glaciers classified as relict might be pseudo-relict, thus potentially containing permafrost. Both supposedly relict rock glaciers investigated by geophysics contain frozen sediments. The majority of the cold springs are mainly associated with rock glaciers with blocky and scarcely vegetated surfaces, but geophysics suggest that permafrost may also exist in rock glaciers below 2000 m a.s.l., entirely covered by vegetation and with a spring-water temperature of up to 3.7 °C. We estimate that pseudo-relict rock glaciers might contain a significant portion (20 %) of all the ice stored in the rock glaciers in the study area. These results highlight the relevance of pseudo-relict rock glaciers in periglacial environments. Even if not a conclusive method, spring-water temperature analyses can be used to preliminarily distinguish between relict and pseudo-relict rock glaciers in wide regions.

3D Electrical Resistivity Tomography Using a Radial Array and Detailed Topography for Tumuli Prospection

ABSTRACTTumuli, ancient burial mounds, stand as intriguing archaeological features, offering valuable insights into past cultures and burial practices. This paper explores the significance of tumuli inspection and utilizes electrical resistivity tomography (ERT) as a noninvasive and powerful tool for inspecting these enigmatic structures, using a nonconventional array. Tumuli, spanning various shapes and sizes, serve as repositories of cultural and funerary traditions, and understanding their internal composition is crucial for unravelling historical narratives. ERT has emerged as a promising geophysical method for investigating subsurface structures, including tumuli. By imaging the electrical resistivity of the ground, ERT enables archaeologists to map variations in soil composition and identify buried features without excavation. This paper reviews the principles of ERT and its application in tumulus studies, showcasing a case study where ERT has successfully revealed internal structures, burial chambers and associated artefacts. The use of 2D ERT is common in tumuli inspection, ignoring accurate 3D effects from the topography. Here we highlight the benefits of the 3D inversion, while we provide a different way to measure which is cost efficient and provides increased spatial resolution to the area of interest. The integration of 3D ERT into archaeological investigations not only enhances our understanding of tumuli construction but also preserves these cultural heritage sites by minimizing the need for invasive excavation. This research contributes to the evolving methodologies in archaeology, emphasizing the synergy between modern technology and traditional archaeological inquiry to uncover the secrets held within tumuli.

Uncovering soil compaction: performance of electrical and electromagnetic geophysical methods

Abstract. Monitoring soil structure is of paramount importance due to its key role in the critical zone as the foundation of terrestrial life. Variations in the arrangement of soil components significantly influence its hydro-mechanical properties and therefore its impact on the surrounding ecosystem. In this context, soil compaction resulting from inappropriate agricultural practices not only affects soil ecological functions, but also decreases the water-use efficiency of plants by reducing porosity and increasing water loss through superficial runoff and enhanced evaporation. In this study, we compared the ability of electric and electromagnetic geophysical methods, i.e., electrical resistivity tomography (ERT) and frequency-domain electromagnetic (FDEM) method, to assess the effects caused by both heavy plastic soil deformations generated by a super-heavy vehicle and the more common tractor tramlines on silty-loam soils. We then tested correlations between geophysical response and soil variables (i.e., penetration resistance, bulk density, and volumetric water content on collected samples) at different homogeneous areas defined by k-means clustering. This work is intended to be a contribution to clarify expectations about the use of geophysical techniques to rapidly investigate soil compaction at various spatial scales, dissecting their suitability and limitations. It also aims to contribute to the methodological optimization of agrogeophysical acquisitions and data processing in order to obtain accurate soil models through a non-invasive approach. Electrical prospecting has finer spatial resolution and allows a tomographic approach, requiring higher logistic demands and the need for ground galvanic contact. On the other hand, contactless electromagnetic induction methods can be quickly used to define the distribution of electrical conductivity in the shallow subsoil in an easier way. In general, compacted soil portions are imaged as high-electrical-conductivity anomalies relative to the context. Results, validated with traditional soil characterization, show the pros and cons of both techniques and how differences in their spatial resolution heavily influence the ability to characterize compacted areas with good confidence.

Enhanced Peat Profiling with Electrical Resistivity Tomography and Multichannel Analysis of Surface Wave

Enhanced Peat Profiling with Electrical Resistivity Tomography and Multichannel Analysis of Surface Wave

Use of electrical resistivity tomography to reduce landfill siting risks in the south-central kentucky karst

Electrical Resistivity Tomography (ERT) can be a key tool for aiding in characterization of karst geohazard risks at proposed landfill sites. This study is proximal to the south-central Kentucky karst and Mammoth Cave National Park and possesses siliciclastic cap rock upland areas that pose relatively high groundwater-contamination risks due to adjacent ravines floored by carbonates. Complex stratigraphy associated with the Mississippian-Pennsylvanian unconformity and juxtaposition of heterolithic sedimentary rocks in general presents further challenges for demarcating hydrogeological characterization of the base of engineered landfills. A conceptual site model integrates ERT surveying and field geology that both satisfactorily characterize the site and risks to groundwater resources without conducting multiple borings. The proposed landfill site is compared to well-known and mapped caves at a landfill near Bowling Green, Crumps Cave near Smiths Grove, and River Styx Spring at Mammoth Cave. Our work entails review of ERT datasets at known cave sites and compares these to two ERT profiles that traversed the proposed landfill site, which are integrated with study of outcrops, and an excavated pit and trench. ERT data range from several low 10 s to about 400 Ω-meter values for mud rock units whereas sandy units possess ERT values from approximately 500 to several tens of thousands of Ω meters. The greatest values are indicative of basal Pennsylvanian Caseyville Sandstone, and these exceed 32,000Ω meters. In comparison, ERT values at known cave sites range from one to 100,000 Ω meters, with elevated, dry rock or possibly dry (air filled) caves interpreted from the greatest values and low values reflective of conductive underground cave streams and moist caves. An unexpected challenge specific to the Hart County landfill study includes occurrence of well-drained and highly weathered Caseyville at the highest elevations of the site causing increased electrical contact resistance during ERT surveying. The overall ERT contrast however, between quartz-rich and clay poor strata (high-resistivity rocks and regolith) and clay-rich strata (low-resistivity rocks) provides independent data consistent with the observed stratigraphy exposed in site exposures. Nonuniqueness of conductive intervals at the Hart County site contrasts with other conductive areas at depth associated with moist or wet cave passages as documented at Crumps Cave and Mammoth Cave.

High-temporal-resolution ERT characterization for vegetation effects on soil hydrological response under wet-dry cycles

Characterization of vegetation effect on soil response is essential for comprehending site-specific hydrological processes. Traditional research often relies on sensors or remote sensing data to examine the hydrological properties of vegetation zones, yet these methods are limited by either measurement sparsity or spatial inaccuracy. Therefore, this paper is the first to propose a data-driven approach that incorporates high-temporal-resolution electrical resistivity tomography (ERT) to quantify soil hydrological response. Time-lapse ERT is deployed on a vegetated slope site in Foshan, China, during a discontinuous rainfall induced by Typhoon Haikui. A total of 97 ERT measurements were collected with an average time interval of 2.7hours. The Gaussian Mixture Model (GMM) is applied to quantify the level of response and objectively classify impact zones based on features extracted directly from the ERT data. The resistivity-moisture content correlation is established based on on-site sensor data to characterize infiltration and evapotranspiration across wet-dry conditions. The findings are compared with the Normalized Difference Vegetation Index (NDVI), a common indicator for vegetation quantification, to reveal potential spatial errors in remote sensing data. In addition, this study provides discussions on the potential applications and future directions. This paper showcases significant spatio-temporal advantages over existing studies, providing a more detailed and accurate characterization of superficial soil hydrological response.

Improving subsurface structural interpretation in complex geological settings through geophysical imaging and machine learning

This study employs seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) to assess subsurface geological conditions along the proposed Porsgrunn Highway in Norway. The primary objective is to analyze SRT and ERT tomograms to identify subsurface geological structures. However, interpreting tomograms is often limited by smoothed boundaries and reduced resolution. To address these challenges, we apply k-means clustering, a machine learning technique that groups data based on similarities in physical properties, to post-process the geophysical tomograms. This study pioneers the use of k-means clustering to interpret tomograms from SRT and ERT data in complex geological settings. We first evaluate the effectiveness of clustering techniques using numerical modeling for two geological scenarios: a horizontally layered case and a layered case with undulation and a fault structure. Utilizing automated methods (Elbow and Silhouette), we objectively determine the optimal number of clusters for each geophysical tomogram. Subsequently, we compare the performance of the k-means clustering algorithm with subjective expert interpretations and the Laplacian edge detection method. Borehole data validate the clustering results and confirm the effectiveness of optimal cluster selection techniques. The findings of this study demonstrate that k-means clustering significantly enhances the detection of geological structures by establishing clearer boundaries and minimizing noise interference, enabling more accurate fault zone delineation. Compared to traditional edge detection and subjective interpretation methods, k-means clustering offers a systematic and objective approach that improves consistency and reliability across diverse geological settings. Moreover, its automated classification of geophysical data into meaningful clusters enables efficient analysis of large datasets. This study underscores the value of integrating machine learning techniques with geophysical methods such as SRT and ERT to improve interpretability and accurately identify subsurface geological structures, particularly in fault zone identification.

Prospection of faults on the Southern Erftscholle (Germany) with individually and jointly inverted refraction seismics and electrical resistivity tomography

As part of the Lower Rhein Embayment (LRE), the Southern Erft block is characterized by a complex tectonic setting that influences hydrological and geological conditions on a local as well as regional level. The study area is located in the south of North Rhine-Westphalia and traversed by several NW-SE-oriented fault structures. Since the tectonic structures were located by past studies based on a sparse foundation of geological data, the positions include considerable uncertainties. Therefore, it was decided to re-evaluate and refine the assumed fault locations by conducting geophysical measurements. Seismic Refraction Tomography (SRT) as well as Electrical Resistivity Tomography (ERT) was performed along seven measurement profiles with a length of up to 1.1 km. In addition to compiling individual resistivity and velocity models for all deduced measurements, ERT and SRT datasets were cooperatively inverted using the Structurally Coupled Cooperative Inversion (SCCI). This algorithm strengthens structural similarities between velocity and resistivity by adapting the individual regularizations after each model iteration. Previously assumed locations of the tectonic structures diverge from the new evidence based on ERT and SRT surveys. Especially in the western and eastern parts of the research area, differences between the survey results and formerly assumed locations are in the order of 100 m. Seismic and geoelectric measurements further indicate a fault structure in the southern part of the area, which remained undetected by past studies. The cooperative inversions do not improve the geophysical models qualitatively, since the individually inverted datasets already provide results of good quality and resolution.

Confirmation of Nature of Palaeo-course of Assi River, India: Some Significant Revelations from Electrical Resistivity Tomography

ABSTRACT A long and continuous palaeo-course of Assi River, in between Prayagraj and Varanasi, in the Ganga River plains with indications of good groundwater potential had been traced from remote sensing data. Electrical Resistivity Tomography (ERT) has been conducted along eight lines for confirmation of the same palaeo-course in general and to specifically ascertain the nature of the course—the past flow conditions and the type of deposits. The variation in the thickness of channel deposits along the concave and convex banks and the middle parts is an indication of lean flow. The mixed fractions of channel deposits are an indication of dumping of sediments in the dying stages of a river. The ERT investigation has further helped in delineating the high resistive palaeo-channels (20 to 50 Ohm.m), the low resistivity aquiclude clay layer (<15 Ohm.m) and the deeper and relatively higher resistivity sandy layer (>50 Ohm.m), which could be the principal aquifer in the area.

Synergistic Application of Geoelectrical Methods for Mapping Placers along the Coastal Periphery of Southern Odisha, India

ABSTRACT This study examines the distribution and amount of placer deposits enriched with heavy minerals along the coastal region of Odisha, India utilizing a combination of geoelectrical techniques. Abundant heavy mineral placers have been identified along the southern coast of Odisha. However, while geological investigations have been conducted, there is a notable absence of geophysical analyses in this specific area. To ascertain both the horizontal and vertical extensions of heavy mineral placer deposits, a comprehensive investigation was undertaken, involving the execution of 23 ERT (Electrical Resistivity Tomography) and TDIP (Time-Domain Induced Polarization) profiles within the designated study zone. These profiles unveiled substantial heavy-mineral zones spanning from shallow layers to depths of approximately 10-15 m. Two primary patterns of mineralization were discerned: firstly, dispersed occurrences which manifested closer to the surface, characterized by irregular black patches of minerals; secondly, concentrated mineralization found at moderate to significant depths, hinting at concealed or buried deposits. Considering the presence of conductive minerals (ilmenite, magnetite) within the beach placers of the study locale, the application of ERT and IP methods proved to be viable. Additionally, the mineralization trends exhibited variance as one traversed from the southwest to the northeast within the study area. Notably, the resistivity of the heavy minerals ranged from 0.1 to 1.1 Ωm, coupled with chargeabilities surpassing 20 mV/V. Significantly, the arrangement of alternating heavy mineralization layers within the sand formations implied the potential presence of stratal anisotropy. Consequently, a specialized code was developed and implemented to perform 2D anisotropic inversion of the ERT data. The application of this anisotropic inversion rectified the depth estimations for concealed pockets of heavy mineralization. While conventional isotropic inversion suggested a concealed mineralization pocket at depths of 15-32 m, the anisotropic inversion revealed that the same mineral-bearing strata existed at depths of 16–28 m.

An improved goal-oriented adaptive finite-element method for 3-D direct current resistivity anisotropic forward modeling using nested tetrahedra

We developed a novel adaptive finite element method (FEM) to address the problem of 3-D direct current (DC) resistivity forward modeling with complex surface topography and arbitrary conductivity anisotropy. The tetrahedra-based FEM and secondary virtual potential algorithm are first used to handle arbitrary complex geo-models. Then, to ensure the accuracy of the simulation solution, an improved goal-oriented adaptive mesh refinement (AMR) algorithm is proposed to realize an optimized mesh density distribution. To avoid the drawback of the traditional goal-oriented AMR algorithm for the DC forward modeling problem, we incorporate a volume-based weighting factor into the posterior error estimation procedure to further optimize the density distribution of the forward modeling grid. In addition, instead of traditional open source mesh generation software, we propose using the longest-edge bisection (LEB) algorithm to perform the mesh refinement process, which can preserve the topological structure between different-level meshes. Finally, the comprehensive test using a two-layered model and two complex 3-D models demonstrate the capability of our newly developed code to obtain highly accurate solutions even on relatively coarse initial grids. By incorporating the volume factor, our novel AMR algorithm achieves a more uniform and reasonable mesh density distribution during these experiments. The LEB refinement technique can generate a series of nested tetrahedral elements and provide fewer tetrahedral elements compared to the traditional Delaunay-based AMR method. The proposed 3-D DC forward modeling method has been implemented into an open source C++ code, which will contribute to the advancement of the 3-D DC resistivity imaging field.

Gas–liquid two-phase flow measurement by using electrical tomography sensors and Venturi

Gas–liquid two-phase flow is characterized by complexity, non-homogeneity and difficulty in modeling. Therefore, traditional measurement methods often struggle to simultaneously meet the requirements of high precision and a wide measurement range. In this context, this study aims to explore an innovative multi-sensor fusion technique to achieve accurate measurement of gas–liquid two-phase flow under full operating conditions. In this study, a combination of three sensors, Venturi, ERT (Electrical Resistance Tomography) and ECT (Electrical Capacitance Tomography), is used to propose a new method based on the fusion of LVF (Liquid-phase Volume Fraction) calculations with flow results. Firstly, the high sensitivity characteristics of ECT and ERT sensors are utilized to obtain spatial distribution information of the flow, which is then used to calculate the LVF. Subsequently, the calculated LVF is combined with the total flow rate measured by the Venturi. Through an established mathematical model, the individual flow rates of the gas and liquid phases are inversely calculated. The results show that the method exhibits high measurement accuracy in different LVF ranges with the relative error controlled within 10%, especially in wet and non-wet gas conditions, which fills the gap of the traditional methods in this field. In addition, the method not only improves the measurement accuracy, but also broadens the measurement range, which meets the diversified needs of complex two-phase flow measurement in the oil and gas industry.

Caves and Fractured Zones Investigation Using 2D Electrical Resistivity Imaging in an Engineering Site, Haqlaniyah, Western Iraq

Engineering risks in karstic areas are represented by cavities and voids near the surface, which are considered potential geotechnical hazards (land subsidence and building cracks). These hazards are caused by dissolution processes that occur when carbonate rocks interact with water, forming weak zones. This study used 2D electrical resistivity imaging with a dipole-dipole array. The spacing of 5 m and an n-factor of 6 were applied to investigate four parallel traverses covering an area of 95x45 m. Electrical resistivity imaging data was inverted using RES2DINV software by robust method inversion. The results show relatively high resistivity values interpreted as massive limestone with cavities and relatively low resistivity values interpreted as fractured limestone with clay or moisture content. Because of the consequence of these caves' haphazard existence in the area, the region was characterized by significant heterogeneity levels of resistivity rise until a depth of 15 m. At that point, they begin to decline.

Geotechnical and Geophysical Characterization of the Aklesal Dablyang Landslide: Implications for Slope Stability

Landslides constitute one of the principal perils in Nepal, particularly within its hilly and mountainous terrains, where a confluence of geological fragility and climatic extremities engenders precarious landscapes. Such hazards precipitate considerable loss of life and property. This investigation centers on the Aklesal Dablyang landslide in Baglung district, a potent menace to local infrastructure, agricultural domains, and human lives. By deploying a synthesis of geotechnical (laboratory-based soil analysis) and geophysical (Electrical Resistivity Tomography (ERT)) methodologies, the intrinsic properties of the soil and rock substrata within the landslide precinct were meticulously examined. The findings reveal that the landslide comprises predominantly loose colluvial deposits with elevated moisture levels, resulting in reduced shear strength and heightened failure susceptibility. The study accentuates the pivotal influence of hydrological phenomena such as surface runoff and groundwater seepage in aggravating slope destabilization. These results underscore the exigency for efficacious risk mitigation strategies to diminish landslide impacts on vulnerable communities. The Aklesal Dablyang landslide exemplifies the intricate interplay of geological and hydrological dynamics within Nepal’s complex topographical context. This research delineates the geotechnical and geophysical determinants of slope stability, highlighting the prevalence of loose colluvial deposits exacerbated by substantial moisture content, which attenuates shear strength and heightens vulnerability to mass movement. ERT analyses divulged a stratigraphy dominated by clayey sand interspersed with cobbles and boulders, which exhibit pronounced susceptibility to mass displacement during intense monsoonal precipitation—a phenomenon exacerbated by climate change. Anthropogenic interventions, including deficient drainage systems and substandard construction methodologies, further destabilize slopes by escalating pore-water pressure and diminishing soil cohesion. The study accentuates the imperative for integrative risk management paradigms, encompassing resilient engineering solutions, hydrological controls, and community collaboration, to bolster resilience against such geo-hazards.

Outdoor mesoscale fabricated ecosystems: Rationale, design, and application to evapotranspiration

The disparity in scale, complexity, and control level between laboratory experiments and field observational studies has shaped both the methodologies employed and the nature of the research questions pursued in ecology and hydrology. While lysimeters and fabricated ecosystems suitably fit in this gap, their use as mesoscale experimental facilities has not been fully explored because of the limited manipulating capabilities and integration with imaging and monitoring methods, particularly for soil functioning. The proposed fabricated ecosystem (4.7 L × 1.2 W × 1.2 H m) focuses on the spatiotemporal integration of point sensors and imaging methods along the soil-plant-atmosphere continuum. Because energy and water fluxes are key environmental drivers, the designed setup was first applied to a multi-approach evapotranspiration investigation. Below the ground, electrical resistivity tomography (ERT) was combined with soil water sensors and a distributed temperature profiling system. Together, they provided the 3D monitoring of water and temperature changes, and thus an estimation of the evapotranspiration, as well as the interpretation of its below-ground controlling processes. Above-ground sensors supported a classical energy balance investigation that was compared with the lysimeter load changes and the ERT-based ET estimation. Our results provide first experimental evidence of water and temperature spatiotemporal variability at the lysimeter scale, and thus explain the discrepancies among the three estimated evapotranspiration time series and their seasonality. Beyond evapotranspiration, the multi-approach investigation of water and energy fluxes emphasizes how mesoscale setups can further support the development and upscaling of methods and models, as well as their integration and application under expected climate disturbances.

Formation of placic horizons in soils of a temperate climate – The interplay of lithology and pedogenesis (Stołowe Mts, SW Poland)

A placic horizon is a thin soil layer that is cemented or indurated by Fe, Mn, and/or Al compounds as well as by organic matter. The placic horizon is a hard, continuous, and nearly impermeable and impenetrable horizon that retards the vertical leaching of water and inhibits the growth of roots. Placic horizons can develop under different climates and in various ways. However, we do not fully understand the interactions between lithology and pedogenesis that might promote placic horizon formation. Therefore, to shed light on the mechanisms of placic genesis, we used an applied multiproxy approach (electrical resistivity tomography – ERT, XRD, 57Fe Mössbauer spectroscopy, bulk geochemistry, soil micromorphology and 14C dating) for three soils developed from sandstone–mudstone parent materials in mountainous areas of SW Poland, to shed light on the mechanisms of placic horizon genesis. The ERT inversion models and soil survey data indicate lithic discontinuities in the profiles. Soil micromorphology data confirmed that a placic horizons formed slightly below the discontinuity. Radiocarbon ages of the placic horizon span from 2.2 to 4.8 ka and suggest that more humid conditions were favorable for the formation of a placic horizon, which aligns with our mineralogical results. Ferrihydrite is the major Fe oxyhydroxide in the placic horizon. Micromorphological data showed that after the formation of the placic horizon, a phase of clay migration might have occurred, while later, podzolisation took over as the main soil-forming process. This sequence shows that thin iron pans can develop independently of other processes and can exist (at least some of them) before the development of a spodic horizon. A placic horizon causes severe hydrological changes in the topsoil and subsurface horizons. Thus, water stagnation in the soil transforms it into a Stagnosol or Planosol and it’s responsible for the evolution of local plant communities and the ecosystem.

Characterization of porewater exchange process and salt release-transport model of multiple geomorphological units in the supratidal zone of muddy tidal flat in semi-arid climate

In the muddy tidal flat controlled by semi-arid climate, porewater exchange (PEX) drives beach surface salt to recharge phreatic brine resources. However, in the Supratidal zone with multiple geomorphological units, the PEX process of such complex areas is still unclear. This study takes the supratidal zone with multiple geomorphological units distributed in the mudflat of Laizhou Bay as the study area. Based on electrical resistivity tomography (ERT) survey and groundwater multi-parameter measurement, the spatiotemporal distribution of salinity in different geomorphological units was described, and the salt release-transport process of these units was finely characterized. The results show that there are spatiotemporal differences in salt distribution in the multi-geomorphological units, and the PEX process is affected by hydraulic gradient, salinity gradient, sediment hydraulic conductivity and bioturbation. The crab burrows enhance the degree of water-salt exchange in the units and drive the salt transport to deeper layers, which leads to the differences in the salt transport process among various units in the PEX. In addition, Due to PEX, the recirculated seawater carries a large amount of salt back to the ocean and accumulate salt at the bottom of the tidal creek during the ebbing tide. Compared with the high tide, the salinity change ratio of the bottom of the tidal creek at the low tide is 261%.

The Use of Textile Electrodes for Electrical Resistivity Tomography in Periglacial, Coarse Blocky Terrain: A Comparison With Conventional Steel Electrodes

The Use of Textile Electrodes for Electrical Resistivity Tomography in Periglacial, Coarse Blocky Terrain: A Comparison With Conventional Steel Electrodes

High-resolution geophysical monitoring of moisture accumulation preceding slope movement—a path to improved early warning

Abstract 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.