In this presentation, we will discuss the increasingly important role of electrical resistivity, induced polarization and self-potential tomography in engineering geophysics and the development of joint approaches that can be applied to image water content, permeability, and water flow at various scales. We will first focus on applications to dams and landslides to demonstrate the usefulness of these methods to locate leaks and get a better understanding of the role of ground water flow in clay-rich landslides and mudflow. Then, we will show case a new model of induced polarization that can be applied to cement and concrete and based on fractal theory. Induced polarization can be used as a non-intrusive and non-destructive technique to image and monitor the evolution of cementitious materials, with the objective of retrieving their water content and hydration state. We will show the performance of the model using a collection of cement paste samples (CEMI and CEMV) and corresponding mortar samples (MORI and MORV), all cured for 60 days, with water-to-cement (w/c) ratios ranging from 0.35 to 0.60. Spectral induced polarization measurements are performed in the frequency range 10 mHz-45 kHz. For the cement pastes, both the in-phase conductivity and the magnitude of the quadrature conductivity increase systematically with increase of the w/c (water-to-cement) ratio. The electrical properties of the mortars scale proportionally with those of the corresponding cement pastes, and the proportionality coefficient can be predicted from the volume fraction of cement. The complex conductivity data are well-fitted by a double Cole Cole model, and the normalized chargeability is found to be proportional to the quadrature conductivity, consistent with theoretical expectations. The experimental data are explained using a dynamic Stern layer model associated with the polarization of the inner component of the double layer coating the surface of the C-S-H minerals. Experiments are also performed to monitor the hydration phase of cement pastes like CEMI. To our knowledge, this is the first mechanistic-based interpretation of the complex conductivity spectra of cement pastes and mortars. These results open new perspectives for non-invasive monitoring of concrete in civil and nuclear engineering applications. We will show some time-lapse tomograms obtained inside the PALLAS project demonstrating this point. Furthermore, we will discuss also some applications to raw earth materials for building construction and how we can use time-lapse tomography to image their water content over time.
How to cite: Revil, A., Ghorbani, A., Abdulsamad, F., Holzhauer, J., Plé, O., Duvillard, P.-A., Vaudelet, P., and Dick, P.: Application of geoelectrical methods in environmental and engineering geophysics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5504, https://doi.org/10.5194/egusphere-egu26-5504, 2026.
Active volcanic areas located within densely urbanized regions require reliable geophysical methods to characterize the subsurface and support seismic hazard assessment and monitoring strategies. The Campi Flegrei area (Southern Italy) represents a paradigmatic example, where hydrothermal activity, fluid circulation, and strong lateral heterogeneities, combined with urban constraints, make subsurface velocity modeling particularly challenging.
In this framework, and in response to the seismic sequence that began in 2023, an extensive campaign of experimental geophysical investigations was promoted and funded by the Italian Department of Civil Protection in the Campi Flegrei area. We present a multi-method seismic investigation based on 66 Horizontal-to-Vertical Spectral Ratio (HVSR), 11 2D seismic array and 20 Multichannel Analysis of Surface Waves (MASW) measurements at 20 sites. Shear-wave velocity (Vs) profiles were derived at each site through joint inversion of the dispersion curve (retrieved from 2D seismic array data and MASW) with ellipticity of the Rayleigh waves.
All HVSR measurements consistently exhibit a low-frequency peak (f0 ≈ 0.2–0.5 Hz), interpreted as the response of the deep caldera fill sediments. Further peaks at frequencies above 0.5 Hz may be associated with shallow impedance contrasts. The fundamental frequency (f0) seems reflecting lateral variations in the depth and stiffness of the caldera fill. Significant variability in HVSR amplitude, sharpness and polarization, reflects the interplay between geological heterogeneity and urban noise sources.
The joint inversion approach reduces model non-uniqueness and provides well-constrained Vs profiles, improving the physical interpretation of HVSR features in terms of stratigraphy and velocity contrasts. This study highlights the potential of HVSR-based methods in active volcanic and urbanized settings and emphasizes the importance of combining passive and active methods to address geological complexity and anthropogenic interference, paving the way for further multi-scale studies and their application in urban volcanic contexts worldwide.
The resulting Vs velocity profiles provide further information for interpreting the stratigraphic features and discontinuities of the caldera fill, useful for integration with other type of studies (hydrothermal alteration) and other type of geophysical data
Moreover, the results of this study offer valuable tools for geohazard assessment and constitute a preliminary step towards the seismic microzonation of the area.
How to cite: Giallini, S., Simionato, M., Caielli, M. G., Catalano, S., Davani, F., de Franco, R., Gaudiosi, I., Fiorentino, G., Mancini, M., Porchia, A., Polpetta, F., Stigliano, F., Tempesta, E., Tentori, D., and Tortorici, G.: Integrated Passive and Active Seismic Methods for Subsurface Characterization of the Campi Flegrei area (Southern Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21551, https://doi.org/10.5194/egusphere-egu26-21551, 2026.
Within the activities of the Geophysical Prospecting Unit (UR2) of the MS Campi Flegrei project, funded by the Department of Civil Protection, shallow and deep geoelectrical tomography surveys as well as passive seismic surveys, including single-station measurements and 2D arrays, were performed. These investigations aimed to support the development of a subsurface geological model of the study area for seismic microzonation. This paper presents and discusses the preliminary results of a Deep Electrical Resistivity Tomography (DERT) survey, reaching an investigation depth of approximately 2 km. Campi Flegrei, located west of Naples, is one of the most active and extensively studied volcanic areas in the world. It is a large caldera formed by massive explosive eruptions that occurred thousands of years ago. In recent decades, the area has been affected by intensified seismic activity and bradyseism, expressed as ground uplift and subsidence driven by subsurface magmatic processes. Several geological and volcanological aspects of the Campi Flegrei caldera are still debated within the scientific community, and many questions remain open regarding the magmatic systems responsible for caldera-forming eruptions. A single, widely accepted model has yet to emerge; however, ongoing and newly proposed investigations continue to improve our understanding of the dynamics of the Campi Flegrei caldera. In this framework, shallow and deep Electrical Resistivity Tomography were carried out in order to obtain the electrical resistivity distribution associated with volcanic features, such as hydrothermal systems, fluid interactions and temperature variations (Finizzola et al., 2006). The acquired DERT data set was processed and elaborated through a procedure built ad hoc for this type of geoelectric surveys (Rizzo et al., 2004) and an optimization of the field work was used to overcome the logistical difficulties of the area (heavy urbanisation, traffic, restricted traffic area, etc.). All the data acquired was appropriately processed (Rizzo et al., 2022) to obtain a 3D model of the subsoil resistivity, providing useful information on the subsoil of the Campi Flegrei volcanic area.
References
Finizola, A. Revil, E. Rizzo, S. Piscitelli, T. Ricci, J. Morin, B. Angeletti, L. Mocochain, and F. Sortino (2006). Hydrogeological insights at Stromboli volcano (Italy) from geoelectrical, temperature, and CO2 soil degassing investigations. Geophysical Research Letters, vol. 33, l17304, 2006
Rizzo E., Colella, A., Lapenna, V. and Piscitelli, S. (2004). “High-resolution images of the fault controlled High Agri Valley basin (Southern Italy) with deep and shallow Electrical Resistivity Tomographies”. Physics and Chemistry of the Earth, 29, 321-327
Rizzo E., V. Giampaolo, L. Capozzoli, G. De Martino, G., Romano, A. Santilano, A. Manzella (2022). 3D deep geoelectrical exploration in the Larderello geothermal sites (Italy), Physics of the Earth and Planetary Interiors, volume 329-330, 106906 doi: https://doi.org/10.1016/j.pepi.2022.106906
How to cite: Rizzo, E., Piscitelli, S., Stigliano, F., and Lapenna, V. and the Working group MS-Campi Flegrei project of CNR (IGAG-IMAA): Deep Electrical Resistivity Tomography (DERT) in the Campi Flegrei area (Naples, Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4950, https://doi.org/10.5194/egusphere-egu26-4950, 2026.
Soil-structure interactions must be properly accounted for also in the assessment of structure vulnerability to seismic inputs. This is particularly true in the case of very large structures where the vibrational response of the structure itself can propagate to the soil also under standard conditions, when the characterization of the soil response is generally carried out. In this contribution we demonstrate how only an integrated approach making use of all available soil characterization techniques (namely MASW, ReMi and HVSR) allows for a correct analysis of the recorded data, eliminating the effects caused by the vibrations caused by the structure itself, and thus focusing only on the soil response itself. In absence of such data integration, directional noise coming from the structure vibration itself may cause gross misunderstanding of the soil characteristics both in terms of soil Vs and natural frequency.
How to cite: Cassiani, G., Nardi, L., Barone, I., Pavoni, M., Boaga, J., Fuggi, A., Elghasti, M., and Brovelli, A.: Soil-structure interaction issues in complex environments: the example of a 250 m high chimney., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4222, https://doi.org/10.5194/egusphere-egu26-4222, 2026.
Recent earthquakes in Türkiye, including the 2020 Samos and 2023 Kahramanmaraş events, have once again underscored the significant impact of local ground conditions and the three-dimensional structure of alluvial basins on earthquake ground motion. In such settings, seismic wave propagation is strongly controlled by basin geometry, sediment thickness, and shear-wave velocity (Vs) contrasts, which can significantly affect ground motion characteristics and increase uncertainties in seismic hazard assessments. For this reason, generating reliable and spatially detailed Vs models at the basin scale has become increasingly important.
The Sakarya Basin, located within the active tectonic framework of the North Anatolian Fault Zone, represents a suitable case study due to its young alluvial deposits and high seismic potential. In this study, the shear-wave velocity structure of the basin is investigated from the surface down to the engineering bedrock through an integrated analysis of ambient noise and seismic data, combining both active and passive seismic methods. Field investigations comprise 533 MASW and ReMi measurements, including 316 newly acquired sites, providing dense coverage of the shallow subsurface. To constrain deeper velocity structures, ambient noise array recordings collected at 61 locations were analyzed using the Spatial Autocorrelation (SPAC) method. The resulting one-dimensional Vs profiles were interpreted together with existing geological and geophysical information and integrated within a GIS-based framework to construct a coherent surface-to-bedrock shear-wave velocity model of the Sakarya Basin.
The resulting model reveals extensive low-velocity sedimentary zones that can delay seismic wave propagation and lead to ground motion amplification within specific frequency ranges. These observations improve the understanding of basin-related site effects and support the identification of areas that may be more vulnerable to seismic amplification. The main contribution of this study lies in the basin-scale integration of high-density active seismic measurements with SPAC-derived ambient noise data, enabling surface-to-bedrock imaging with a level of spatial resolution not previously available for the Sakarya Basin. The resulting Vs model provides an improved representation of both shallow and deep subsurface conditions, offering valuable insights for site classification and basin-related ground motion studies. This research was conducted within the scope of the TÜBİTAK-funded project no. 124Y188.
How to cite: Silahtar, A., Şenkaya, M., Karaaslan, H., and Budakoğlu, E.: Surface-to-Bedrock Imaging of the Sakarya Basin Based on Integrated Analysis of Ambient Noise and Seismic Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18388, https://doi.org/10.5194/egusphere-egu26-18388, 2026.
In emergency engineering contexts, conventional gravity-processing workflows based on Bouguer anomaly computation are often impractical, as they require high-resolution digital elevation models and assumptions about terrain density, both of which introduce delays and additional uncertainty.
Following a localized collapse beneath track 2 at the EAV Pozzuoli railway station (Naples, Italy), a microgravity survey was conducted to support rapid subsurface characterization. Optical inspections indicate that the cavity extends approximately 4.5 m deep and 6 × 6 m, and affected both tracks, and caused visible settlement of the station platforms. The objectives of the gravity investigation are to assess (i) the spatial relationship between the detected cavity and the pedestrian underpass connecting the station building to platform 2, and (ii) the downstream path of wastewater.
In this study, we adopt a fast gravity data processing strategy to estimate the gravity component generated by lateral subsurface density contrasts (Florio et al., 2025). A linear regression between Free-Air Anomalies and elevation enables a parameter-free decomposition of the gravity field into a terrain-correlated component (TCA) and a terrain-uncorrelated component (TUCA). This approach enhances the detection of anomalous features such as cavities or mass deficits and allows for the independent estimation of average terrain density.
TUCA processing is rapid, requires minimal input data, and can be performed directly in the field, making it particularly suitable for preliminary evaluations in time-critical geotechnical settings. This paper presents the TUCA workflow and its application to the Pozzuoli railway station case study, including the survey design and key results.
How to cite: Milano, M., Florio, G., Ferrara, G., Cella, F., and Ricciardi, L.: Rapid Microgravity Assessment of Subsurface Cavities Using Terrain-UnCorrelated Anomalies, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21992, https://doi.org/10.5194/egusphere-egu26-21992, 2026.
In some cases, soils exhibit a layered structure clearly identified even at the depth scales investigated by Ground Penetrating Radar (GPR) surveys. However, not many methods and computational tools are available that systematically address imaging in layered soils. Imlaymed (Imaging in Layered Media) is a Python graphical user interface (GUI) freeware software specifically designed to tackle this problem. The code assumes either a two layered soil or a cavity embedded within a homogeneous soil. In the latter case, the cavity is locally interpreted as a three-layered medium. The interfaces between adjacent layers are assumed smooth—which is geologically reasonable—although not necessarily planar. However, the non-flatness of the layers precludes the possibility of obtaining an analytical solution. Consequently, Imlaymed addresses the focusing and time–depth conversion issues as an imaging problem rather than an inverse scattering problem. The method explicitly accounts for the presence of two distinct propagation velocities within the soil, which results in geometric distortions, including dilation and compression effects on both the targets and the distances among them. Imlaymed aims to mitigate these distortions. The current release represents an initial version of the software, to be progressively updated and extended. Future developments are expected to introduce additional capabilities—e.g. time-reverse migration—and to enhance the existing features, e.g. through the incorporation of AI techniques and the optional use of parallel computing. In particular, Imlaymed will aid to generation of slices directly in the spatial domain instead of the common slices built up in time domain.
The methodology underlying the code is based on our previous results [1-6]. The implementation of this code has improved both the computational efficiency and the ease of use of the algorithms. Notwithstanding, the user of Imlaymed is supposed to have some non-too-basic background experience in GPR prospecting.
Imlaymed is distributed under AUL/ANCL License (Academic Use License/Academic Non-Commercial License).
Acknowledgements
This work has been implemented within the activities of the Research Project “Georadar e avanzamento delle investigazioni: un’applicazione economica alla sicurezza stradale”, financed by University of Calabria.
References
- Persico, G. Morelli, Combined Migrations and Time-Depth Conversions in GPR Prospecting: Application to Reinforced Concrete, Remote Sens. 2020, Volume 12, Issue 17, 2778, open access, DOI 10.3390/rs12172778.
- Persico et al. “A posteriori insertion of information for focusing and time–depth conversion of ground-penetrating radar data”, Geophysical Prospecting, open access, https://doi.org/10.1111/1365-2478.13369, 2023.
- Persico et al., GPR mapping of cavity in complex scenarios with a combined time-depth conversion, Sensors, MDPI, Sensors 2024, 24(10), 3238; https://doi.org/10.3390/s24103238, 2024.
- Persico et al., An innovative time-depth conversion for the management of buried scenarios with strong discontinuities, Journal of Applied Geophysics vol. 227, 105435, DOI 10.1016/j.jappgeo.2024.105435, 2024.
- Yang et al., Accounting for the Different Propagation Velocities for the Focusing and Time–Depth Conversion in a Layered Medium, Applied Sciences 14(24):11812, 2024.
- Persico et al., Retrieving the propagation velocity of the electromagnetic waves in a two-layered medium through the diffraction curves, Near Surface Geophysics, 1–13. https://doi.org/10.1002/nsg.70028, 2025.
How to cite: Esposito, G., Capparelli, F., Catapano, I., Capozzoli, L., De Martino, G., Morelli, G., Yang, D., and Persico, R.: Imlaymed: a freeware software for the GPR imaging of stratified soils, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7452, https://doi.org/10.5194/egusphere-egu26-7452, 2026.
This work is supported by the projects TOGETHER – Sustainable geothermal energy for two Southern Italy regions: geophysical resource evaluation and public awareness (https://www.together-prin.it/) and ITINERIS – Italian Integrated Environmental Research Infrastructures System (https://itineris.cnr.it/), funded by the European Union – Next Generation EU (PNRR, M4C2, Investments 1.1 and 3.1, respectively).
As part of the ITINERIS project, the geophysical laboratory of CNR-IMAA was upgraded with advanced geophysical instrumentation characterized by lower operational costs, increased flexibility, higher sensitivity, and faster acquisition rates. The availability of dense and flexibly deployable geophysical sensors significantly improves survey resolution, particularly in complex urban and semi-urban environments, thereby supporting sustainable and resilient urban development.
Under the TOGETHER project, the upgraded instrumentation was tested at pilot sites, including the Sele River Valley (SRV) in the Campania region (Southern Italy). This area hosts numerous thermal springs and wells with temperatures reaching up to 48 °C, currently used for spa and therapeutic purposes. These characteristics make the SRV a natural laboratory for testing integrated geophysical approaches aimed at identifying geothermal targets in proximity to existing communities and infrastructure.
Geothermal energy, particularly low- to medium-enthalpy systems, represents a key renewable resource for the energy transition, enabling the sustainable exploitation of local resources, the reduction of greenhouse gas emissions, and the strengthening of regional energy resilience. Integrated geophysical investigations play a crucial role in reducing exploration uncertainty and promoting environmentally responsible geothermal development.
In the SRV area, geophysical surveys were conducted over a target zone of approximately 6 × 8 km², centered on the hottest thermal manifestations. A comprehensive geophysical dataset was successfully acquired in a challenging urban and semi-urban context characterized by logistical constraints and high levels of anthropogenic noise. Multi-scale and multi-resolution three-dimensional subsurface electrical resistivity models were derived using shallow and deep Electrical Resistivity Tomography (ERT/DERT) and Magnetotelluric (MT) surveys. In parallel, ambient seismic noise recordings were acquired and processed using single-station HVSR analyses and array-based Ambient Noise Tomography (ANT).
In parallel with fieldwork, public engagement activities were implemented to foster trust and collaboration with local stakeholders. These activities included the involvement of high school students and teachers, communication through municipal social media channels, the distribution of participation certificates, and the organization of a final dissemination event aimed at citizens, local institutions, schools, and stakeholders. The event was dedicated to sharing the results and research activities developed in the area as part of the TOGETHER project, with a particular focus on energy sustainability and the enhancement of local geothermal resources, also through direct dialogue between researchers and the public. These initiatives proved essential for ensuring transparency, site accessibility, and awareness of local geothermal potential.
The results demonstrate the feasibility and effectiveness of an integrated geophysical and participatory approach, highlighting the importance of public engagement and standardized workflows for sensor deployment and data processing.
How to cite: Giampaolo, V., Serlenga, V., Balasco, M., De Martino, G., Perrone, A., Stabile, T. A., Lapenna, V., Napolitano, F., Rizzo, E., Panebianco, S., Martino, L., Capuano, P., Blasone, M., Bubbico, D., Cataldo, V., and Amoroso, O.: Integrated geophysical and participative approaches for geothermal resources evaluation in urban areas in Southern Italy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11446, https://doi.org/10.5194/egusphere-egu26-11446, 2026.
In a context where low-carbon transport is becoming increasingly essential, the diagnosis and maintenance of railway infrastructure have become critical issues. Current assessment techniques still rely heavily on destructive testing of embankments, sublayers, and underlying soils. These structures are also exposed to more frequent and less predictable extreme weather events, threatening their mechanical integrity and long-term stability. High-density, high-resolution geophysical methods therefore offer a compelling non-destructive alternative, particularly for characterizing and monitoring the mechanical properties of soils. Over the past decade, major advances have been made in seismic acquisition, processing, and interpretation. We present an overview of our recent contributions, mainly based on surface wave-methods, which require low energy sources and are well suited to railway environments (Cunha Teixeira et al., 2025a). We have developed high-efficiency acquisition strategies using landstreamers, combined with conventional active sources (weight drop or hammer) and passive sources (induced by trains or traffic). We present PAC (Cunha Teixeira et al., 2025b), a user-friendly application designed for processing multichannel analysis of surface waves (MASW). It integrates stacking and interferometry-based approaches to extract multimodal dispersion images, enabling the detection of lateral variations within embankments or continuous site monitoring. Deep learning supports semi-automatic picking, while Bayesian inversion (Burzawa et al., 2025) facilitates the interpretation of mechanical models and aids reliable decision-making in railway infrastructure management.
References:
Burzawa, A., Bodet, L., Dangeard, M., Barrett, B., Byrne, D., Whitehead, R., Chaptal, C., Cunha Teixeira, J., Cárdenas, J., Sanchez Gonzalez, R., Eriksen, A., Dhemaied, A. (2025). Efficient mechanical evaluation of railway earthworks using a towed seismic array and Bayesian inference of MASW data. arXiv preprint https://doi.org/10.48550/arXiv.2507.16491
Cunha Teixeira, J., Bodet, L., Rivière, A., Solazzi, S.G., Hallier, A., Gesret, A., El Janyani, S., Dangeard, M., Dhemaied, A., Boisson Gaboriau, J. (2025a). Neural machine translation of seismic ambient noise for soil nature and water saturation characterization. Geophysical Research Letters, 52(13) https://doi.org/10.1029/2025GL114852
Cunha Teixeira, J., Burzawa, A., Bodet, L., Hallier, A., Decker, B., Lin, F., Dangeard, M., Boisson Gaboriau, J., & Dhemaied, A. (2025b). Passive and Active Computation of MASW (PAC). Zenodo. https://doi.org/10.5281/zenodo.17639980
How to cite: Bodet, L., Cunha Teixeira, J., Burzawa, A., Dangeard, M., Hallier, A., Boisson Gaboriau, J., and Dhemaied, A.: PAC, a User-Friendly App for Hybrid Active-Passive MASW along Linear Geotechnical Infrastructures: Application to Advanced Seismic Diagnosis of Railway Embankments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3143, https://doi.org/10.5194/egusphere-egu26-3143, 2026.
Carbonate terrains of the Eastern Province of Saudi Arabia are highly susceptible to subsurface hazards due to intense weathering, fracturing, and karstification. Features such as dissolution cavities, weakened zones, and fault-related discontinuities pose significant risks to infrastructure in a region experiencing rapid urban and industrial development. Accurate and non-invasive characterization of these concealed features is therefore critical for geotechnical risk mitigation.
This study investigates the effectiveness of the Multichannel Analysis of Surface Waves (MASW) technique for identifying and characterizing karst features and fault zones in complex carbonate environments. MASW utilizes the dispersive behavior of Rayleigh waves to derive shear-wave velocity (Vs) profiles, which are sensitive to variations in material stiffness, fracturing, and void development. These velocity contrasts provide valuable indicators of subsurface heterogeneity associated with karst and structural deformation.
Field investigations were conducted at representative sites exhibiting varying degrees of carbonate weathering and karst development. Prior to full-scale data acquisition, parameter sensitivity analysis is performed to optimize survey design, including geophone spacing, spread length, source offset, and sampling interval. MASW data were processed through dispersion analysis and inversion to generate detailed Vs profiles and lateral velocity variations. Anomalous low-velocity zones and abrupt velocity gradients are interpreted as indicators of cavities, fractured layers, and fault zones. The results demonstrated that MASW provides reliable, high-resolution subsurface characterization in karst-prone carbonate terrains, offering a cost-effective and non-invasive tool for identifying geotechnical hazard zones and supporting safer infrastructure planning.
How to cite: Sabir, T. U. R., Mohd Muztaza, N. B., and Jadoon, K. Z.: High-Resolution Multichannel Analysis of Surface Waves (MASW) Imaging of Karst Features in Carbonate Environments of Eastern Saudi Arabia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6403, https://doi.org/10.5194/egusphere-egu26-6403, 2026.
In the last 15 to 20 years, a sudden spike of liquefaction events after groundwater rebound on inner dumps in the Lusatian mining district resulted in around 30,000 hectares of land being closed to public access. One of the common modern compaction methods used is the gentle-blast-compaction (GBC), in which minimal explosive charges are placed in defined depth horizons (below the groundwater table) and detonated one after the other from the bottom upwards. The primary objective is to improve the ground stability by locally collapsing the pore structure of the material. This increases the bulk density of the dump material and reduces the air and waterfilled proportion of the pore space. Usually, direct geotechnical methods like drillings or cone penetration tests (CPT) are used to verify successful compaction. Within the “VerLaUf” project, we investigate the suitability of various airborne and ground-based geophysical methods for the non-invasive evaluation of these compaction measures. In the present study, we focus in particular on the applicability of two electromagnetic methods, transient electromagnetics (TEM) and surface nuclear magnetic resonance (SNMR). The TEM measurements are used to obtain a resistivity model of the subsurface which is needed for the inversion and interpretation of the SNMR data. Due to the direct correlation between SNMR signal amplitude and water content (porosity) as well as SNMR relaxation time and pore size, the SNMR method promises not only qualitative but also quantitative results about the change in the (water-filled) pore space after GBC.
Field campaigns were carried out over the course of three years, where the GBC took place after the first measurement campaign at depths ranging from 7 m to 32 m. The subsequent measurement campaigns were carried out after the GBC, with waiting times of approx. five and 15 months, respectively. The TEM and SNMR measurements consisted of 1D soundings along a 2D profile which was about 450 m long. One reference point, without GBC and about 400 m away from the profile, was measured for comparison and to identify seasonal variations in the data. All measurements were carried out with identical field setups and measurement parameters (loop size, number of averaging measurement repetitions, etc.). The recorded data were processed in an identical manner and a QT-inversion was used to derive a depth resolved partial water content model, i.e., the water content as function of depth and relaxation time. Due to the noisiness of the SNMR data, we used a permeability index, a combination of SNMR signal amplitude and relaxation time, to evaluate the results. By doing so, we reduce the inherent ambiguity (especially in noisy data) between the two parameters. Comparing the results from the first with the last field campaign shows, that a reduction of the permeability index within the GBC targeted layers of about 33 percent is detected, which is indicative for a respective compaction.
How to cite: Hiller, T., Costabel, S., Erdmann, G., and Schönfeldt, E.: Using surface-NMR measurements to study the effects of compaction measures on the properties of lignite mining dumps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17896, https://doi.org/10.5194/egusphere-egu26-17896, 2026.
Characterizing fracture networks in deep (hundreds-of-meters) crystalline rock is a key requirement for assessing the suitability of a high-level radioactive waste repository site. Hydraulically conductive fracture networks may act as preferential groundwater pathways and therefore need to be identified for long-term safety assessment. In line with the geophysical exploration objective to investigate and visualize connected fracture networks in deep rock, this study proposes an integrated interpretation strategy combining borehole-based multi geophysical data systems. This work is part of a basic research project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) entitled “Development of Core Technologies for Characterization and Modeling of Fractured Rock in the Assessment of Site Suitability for High-Level Radioactive Waste Disposal”.
This study aims to identify and quantitatively characterize major fracture-network intervals around the borehole by integrating acoustic televiewer (ATV) borehole imaging logs with borehole radar data. ATV provides high-resolution structural information for fractures penetrating the borehole wall, including dip, dip direction, and aperture (where resolvable). However, because ATV observation is confined to the borehole wall image, it has limited capability to evaluate the continuity and spatial distribution of the fractures around the borehole. In contrast, while quantitative characterization of detailed fracture geometry (e.g., orientation and aperture) from borehole radar data alone is difficult, it can image relatively large and continuous fractures within approximately 10-15 m of the borehole that may be hydraulically conductive. Borehole radar method can also detect fractures that do not directly intersect the borehole. Using these complementary strengths, we propose the joint interpretation strategy to image major fracture-network candidates around borehole and to infer their dip, dip direction, aperture, and relative continuity. In addition, we demonstrate the workflow through a case study with field data.
The case study was conducted using ATV and borehole radar datasets acquired from a KIGAM borehole down to a depth of 100 m. First, based on the ATV log, fracture characteristics (e.g., dip, dip direction, and aperture) were analyzed, and major fracture-network intervals with clustered fractures were identified. Then, near-borehole (early-time) reflection events in the borehole radar data were analyzed to evaluate their relationship with the major fracture-network intervals derived from the ATV log. In particular, distinct reflectors observed at relatively later times (i.e., beyond the near-borehole) in radar data were matched to the major fracture-network intervals derived from ATV to estimate the relative continuity of them around the borehole. The proposed borehole-based integrated ATV and radar interpretation strategy enables characterization of major fracture networks and is expected to provide a practical approach for screening and visualizing deep fracture networks associated with the stability of repository sites.
How to cite: Uhm, J., Jo, Y., Kang, W., Lee, T., and Park, J.-W.: Case study: Integrated interpretation of borehole acoustic televiewer (ATV) and radar data for imaging major fracture networks in crystalline rock, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3235, https://doi.org/10.5194/egusphere-egu26-3235, 2026.
Transportation networks rely heavily on bridges whose safe operation depends on maintaining structural soundness. Natural phenomena, such as landslides and human-induced incidents, pose significant threats to bridges, with consequences ranging from compromised safety to complete failure and service interruption. Multiple variables determine the extent of structural deterioration, including the nature of hazardous events, material composition, and existing maintenance conditions. A comprehensive evaluation of landslide-related threats necessitates examining a variety of factors, including the geophysical properties of the subsoil and an in-depth knowledge of the bridge key structural elements, such as its foundations, piers, and abutments, as well as their current state of conservation.
Supported by the FABRE consortium, the EMILI project - ElectroMagnetic techniques for Investigating Landslide and structural damages due to their Impacts on bridges - aims to establish uniform protocols and operational frameworks for electromagnetic investigation techniques in bridge-landslide hazard evaluation. By targeting Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR), EMILI advances the standardization, reliability, and field implementation of electromagnetic approaches.
Initial findings from EMILI are discussed here, encompassing two primary contributions. The first concerns a comprehensive literature analysis examining both capabilities and constraints of ERT and GPR in field applications involving bridges, landslides, and their interactions. The second deals with preliminary results from simplified numerical models exploring the detection potential of ERT and GPR when applied via conventional and unconventional measurement configurations. Specifically, surface and borehole data from simulated scenarios involving diverse lithologies, foundations, and water content are considered and processed to establish the potential and limitations of ERT and GPR in estimating the shape and depth of the foundation piles.
Preliminary synthetic results are promising and demonstrate the capability of ERT and GPR to identify foundation structures in simplified geological contexts.
How to cite: Capozzoli, L., Catapano, I., Ludeno, G., Esposito, G., Gennarelli, G., Noviello, C., Soldovieri, F., De Martino, G., Di Gennaro, D., Romano, G., Giampaolo, V., Perrone, A., Lapenna, V., Ormando, C., Di Pietro, A., Pollino, M., Buffarini, G., Lipari, A., Clemente, P., and Giocoli, A.: Electrical Resistivity Tomography and Ground Penetrating Radar for Bridges: Preliminary Findings from the EMILI Project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10509, https://doi.org/10.5194/egusphere-egu26-10509, 2026.
Historical urban centres of high cultural and monumental relevance are commonly characterized by complex and highly heterogeneous subsurface settings, resulting from the superposition of natural geological deposits, archaeological layers, and centuries of anthropogenic modifications. In such contexts, limited or fragmented subsurface knowledge may hinder archaeological interpretation and constrain multidisciplinary analyses aimed at urban reconstruction and heritage preservation.
This contribution is framed within the Italian PRIN 2022 project NEW AGE (New Integrated Approach for Seismic Protection and Enhancement of Heritage Buildings on Historic Earthen Deposits) and presents results from non-invasive geophysical investigations conducted at two emblematic monumental sites: the Roman Amphitheatre (Arena) of Verona and the Santa Sofia monumental complex in Benevento, both characterized by prolonged and stratified occupation histories, leading to highly heterogeneous near-surface conditions. The investigations benefited from advanced geophysical instrumentation made available through the IRPAC and ITINERIS research infrastructure (funded through regional and national programs, respectively), supporting enhanced data acquisition capabilities within the project framework.
We propose a multi-scale, multi-method geophysical approach designed to improve the characterization of shallow subsurface conditions in densely built and historically layered urban environments. The investigation strategy combines ground-penetrating radar (GPR), electrical resistivity tomography (ERT), and seismic methods, selected to explore complementary physical properties and depth ranges while accommodating site-specific logistical and conservation constraints.
GPR surveys provided high-resolution imaging of shallow subsurface heterogeneities and anthropogenic features, supporting the identification of archaeological remains and spatial variations within near-surface layers. ERT investigations complemented these results by resolving broader geological structures and deeper resistivity contrasts, allowing reconstruction of subsurface variability at different spatial scales. Seismic measurements contributed additional constraints on subsurface layering and mechanical properties.
The combined interpretation of the different datasets acquired, supported by archaeological and geotechnical information where available, provides a robust and physically consistent reconstruction of the shallow subsurface in complex, historically layered monumental settings. The multi-method geophysical framework enables the identification of stratigraphic heterogeneities, anthropogenic layers, and buried structures, reducing subsurface uncertainty in complex heritage contexts and supporting subsequent geological, archaeological, and engineering analyses.
How to cite: Calamita, G., Capozzoli, L., De Martino, G., Bellanova, J., Piscitelli, S., Perrone, A., Martino, L., and Gallipoli, M.: Near-surface geophysics for characterizing complex subsurface settings in historically layered monumental urban areas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21428, https://doi.org/10.5194/egusphere-egu26-21428, 2026.
