To address this gap, geological and geomorphological surveys were integrated with Electrical Resistivity Tomography (ERT) and Horizontal-to-Vertical Spectral Ratio (H/V) analyses of ambient seismic noise and earthquake recordings. The combined dataset constrains both the internal architecture and the dynamic response of the landslide body. ERT imaging identifies a resistivity discontinuity at approximately 20–30 m depth, while H/V analysis reveals a consistent seismic impedance contrast at comparable depths, interpreted as a lithological boundary within the unstable mass rather than the sliding surface. Within the landslide, H/V results show a spatially variable response. Along the longitudinal axis, spectral signatures are consistent with quasi-one-dimensional resonance conditions, enabling simplified inversion and depth estimation. Toward the margins, broadened and asymmetric peaks, coupled with pronounced azimuthal dependence, indicate multidimensional effects related to lateral heterogeneity, structural disruption, and geomorphological control. Azimuthal analysis further highlights a partial geometric correspondence between preferred vibration directions, slope morphology, and previously documented displacement vectors. The identified resonance frequencies (2–4 Hz) fall within the range commonly reported for low- to mid-rise masonry buildings in similar geological contexts. Although no direct measurements of structural response were performed, this correspondence suggests that possible soil–structure interaction effects may warrant further investigation. Overall, the results demonstrate that non-invasive geophysical methods provide a consistent framework for characterizing the subsurface and dynamic behaviour of urban landslides, supporting improved multi-hazard assessment and risk-informed planning in complex Apennine settings.

Within the context of seismic risk assessment, the prediction of the dynamic response of natural slopes is strictly related to the accurate definition of the geotechnical subsoil model. This aspect is particularly challenging for those slopes characterised by the presence of buried morphologies, for which the vertical and lateral heterogeneities of the subsoil setting may predispose them to additional risks during seismic events. The paper proposes a methodological procedure aimed at identifying preliminary subsoil models of areas characterised by uneven topography and buried lithological bodies of uncertain morphology, through the comparison of parametric site response analyses and site-specific geophysical surveys. The procedure, tested with reference to the prototype case study of Costa del Canneto slope in Southern Italy, proves to be a useful tool to reduce the uncertainties associated with the presence of complex subsoil settings, including potential buried morphologies. Indeed, over several geotechnical models tested, the numerical analyses provide amplification profiles of the fundamental frequency reasonably comparable with data from ambient vibration measurements only for few of them. This allows to restrict the number of possible slope models and can be used to guide the design of additional in-situ geotechnical investigations needed to better characterise the stratigraphy of the area and constrain the geometry of the expected buried morphologies.

The vulnerability to landslides of the Basilicata territory (southern Italy) depends on different causes such as the outcropping lithologies, the morphology of the reliefs, neotectonics, seismicity, etc. Currently all 131 municipalities in this region are involved by landslides (IFFI Project 2020) that very often have affected the continuous and discontinuous urban fabric as well as industrial or commercial areas. In many cases, as for example in the Gorgoglione test site, the state of emergency has been declared with evacuation orders for residential buildings and commercial activities (Perrone et al., 2021; Calamita et al., 2023). Traditional direct techniques, such as geotechnical boreholes, offer point-specific information but can be highly invasive, leading to potential damage to economic and cultural resources such as archaeological sites and underground utilities in the upper layers of the subsoil. In the context of investigating landslides in urban areas, alternative approaches may be more suitable. A significant contribution can be achieved through the combined utilization of remote sensing and in situ geophysical techniques. (Perrone et al., 2006). In this work, satellite and ground based SAR interferometry, electrical resistivity tomography (ERT) and single-station seismic ambient noise measurements (HVSR) have been integrated for investigating the phenomenon affecting the Gorgoglione urban area (Fig.1), located in the south-western part of Matera Province (Basilicata Region). SAR interferometry results provided information on the activity status of the phenomenon. The ERT and the HVSR allowed the reconstruction of the subsoil geological setting, the identification of physical discontinuities correlated with lithological boundaries and sliding surfaces and the location of high water content areas. This information was used to assess the landslide residual risk, to plan and implement the risk mitigation actions and to correctly design the remediation works. References Calamita G., Gallipoli M.R., Gueguen E., Sinisi R., Summa V., Vignola L., Stabile T.A., Bellanova J., Piscitelli S., Perrone A.; 2023: Integrated geophysical and geological surveys reveal new details of the large Montescaglioso (southern Italy) landslide of December 2013. Engineering geology 313 , pp. Art.n.106984-1–Art.n.106984-16. IFFI Project (Inventario dei Fenomeni Franosi in Italia). ISPRA, Dipartimento Difesa del Suolo, Servizio Geologico d’Italia. Available online: http://www.progettoiffi.isprambiente.it/cartanetiffi/ (accessed on May 2020) Perrone A., Canora F., Calamita G., Bellanova J., Serlenga V., Panebianco S., Tragni N., Piscitelli S., Vignola L., Doglioni A., Simeone V., Sdao F., Lapenna V.; 2021: A multidisciplinary approach for landslide residual risk assessment: the Pomarico landslide (Basilicata Region, Southern Italy) case study. Landslides 18, 353–365. Perrone A., Zeni G., Piscitelli S., Pepe A., Loperte A., Lapenna V., Lanari R.; 2006: Joint analysis of SAR interferometry and electrical resistivity tomography surveys for investigating ground deformation: the case-study of Satriano di Lucania (Potenza, Italy). Engineering Geology 88, 260–273.

Landslides are a significant geomorphological factor in the natural evolution of the Southern Apennines slopes (South Italy), with earthflows being one of the most representative types. The development of large earthflows in this region is primarily due to extensive clay-rich outcrops, whose activation was facilitated by warm, humid Holocene climates. These earthflows can be very extensive, often affecting entire slopes and exhibiting numerous minor reactivations over time. This study focuses on the Pietra Maura earthflow in the Marsico Nuovo Municipality (Basilicata Region), integrating detailed geological and geomorphological investigations with geophysical techniques to characterise and better understand its evolution. The landslide extends approximately 4.2 km NW-SE, with an average width of 900 m, and affects the area below the maximum level of the Marsico Nuovo dam and two urban zones, crossing roads, power lines, and aqueducts, necessitating ongoing monitoring to prevent damage. To better understand the extent and dynamics of the Pietra Maura earthflow, a detailed geological and geomorphological survey was conducted, supported by advanced geophysical techniques, such as Interferometric Synthetic Aperture Radar (InSAR) and Electrical Resistivity Tomography (ERT). InSAR data from Copernicus Sentinel-1 satellites revealed detailed east-west ground deformation patterns, while ERT helped reconstruct the earthflow’s geometry, showing a variable thickness of up to 50–60 m and identifying sectors with high-water content. The findings provide essential insights for taking appropriate actions to stabilise the landslide and improve area management.

Exploring the ‘fragile crust of our planet’ is crucial for human survival holding an immense social and economic significance. Therefore, innovative approaches become of utmost importance for obtaining precise subsoil models in urban areas making the latter more resilient to natural disasters. Due to logistic issues and a high level of anthropogenic disturbance and related background noise, urban areas are usually intrinsically more problematic for applying geophysical prospecting methods. This work presents the results obtained by Deep Electrical Resistivity Tomography and P wave Seismic Reflection surveys performed along the Ferrara, north Italy, city walls documenting the adaptability of the geophysical surveys and how it is possible to obtain high-quality electrical resistivity and seismic data even in complex urban settings. The joint interpretation of geoelectrical and seismic data fully integrated with tectonic, geological and hydrogeological information allowed to reconstruct the stratigraphic evolution down to a depth of about 1.5 km. These results highlight the occurrence of a syndepositional Quaternary tectonic tilting associated with the growth of a fault-propagation fold.

A methodological approach based on the integration of different survey techniques may be particularly suitable for the study of areas with complex geology such as those affected by landslide phenomena. The results obtained by the application of combined electrical resistivity tomography (ERT) technique, ambient seismic noise mea-surements (single station and array), geological investigation and granulometric analysis to characterize and study a landslide occurred on December 3rd, 2013 in Basilicata region (southern Italy) are presented and dis-cussed. The landslide partially affected the peri-urban area of Montescaglioso town and caused damages to small -medium enterprises, infrastructures, and housing. The analysis of ambient noise signals made possible to esti-mate the depth of the contacts between the main geological formations outcropping in the area and revealed the existence of directional resonance effects. The discontinuities observed by the ERT have confirmed the presence of different lithotypes and allowed illuminating the sliding surface at a depth of about 40 m in agreement with the seismic results and boreholes data. The shallow discontinuities inferred from geophysical surveys were supported also by the results of a detailed granulometric analysis performed on a geognostic survey, confirming the presence of a heterogeneous sedimentary deposit in the area. In such complex context, the acquisition of spatially distributed geophysical properties permitted to increase the knowledge of the geological setting of the area, reaching a level of detail that cannot be observed by applying only a sparse discrete direct sampling. The integration of all the obtained information allowed the delineation of geophysical discontinuities related to the presence of sliding or weakness surfaces and areas with high water content that could contribute to future activation of the movement. This information was crucial to better understand the nature of the landslide, contributing to the planning and the implementation of risk mitigation actions and to the design of remediation works.

Italy is one of the European countries most affected by landslides. In order to mitigate the risk, the analysis of such phenomena should involve a broad spectrum of studies to understand the geological and geomorphological properties of the unstable areas, the geometric features of the landslides and the causes of their trigger, the evolution over time, and the works of risk mitigation taken as well as their effectiveness over time. This article is concerned with multidisciplinary investigations on a historical earth flow occurred in Montemurro (Basilicata, Southern Italy) in 1907. We analyse unpublished archive sources strictly coupled with new geological and geomorphological surveys. Furthermore, to gain information on the geometrical features of the landslide body, geophysical prospections (ERT) is used alongside the field surveys. Lastly, to gain insight on the landslide triggering factors, we employed historical–climatological analysis: in particular, we made use of the monthly simple daily intensity index (SDII) to evaluate extreme events and the standardised precipitation index (SPI) to consider previous wetness conditions. The earth flow was triggered on 26 February 1907 and the main movement lasted about one week, involving several buildings, including those of cultural interest. Historical documentary investigations and historical climatological analysis both indicate that the earth flow was triggered by a preceding heavy rain period, which independent historical sources suggest also caused the activation of landslides over a wider area around Montemurro. Currently, the earth flow is NE–SW oriented, extends for a length of ~1.1 km, and has an average width of ~220 m. The landslide is in a dormant activity phase. From a methodological point of view, the research stresses the importance of integrated approaches to investigate natural hazards, particularly by the use of historical data. This research may be of interest to academics, practitioners, and policymakers for both the methodological approach followed and results gained, useful in view of both risk mitigation and territorial planning of landslide-prone areas.

Nowadays, policies addressed to prevention and mitigation of seismic risk need a consolidated methodology finalised to the assessment of local seismic response in explosive volcanic settings. The quantitative reconstruction of the subsoil model provides a key instrument to understand how the geometry and the internal architecture of outcropping and buried geological units have influence on the propagation of seismic waves. On this regard, we present a multidisciplinary approach in the test area of the Stracciacappa maar (Sabatini Volcanic District, central Italy), with the aim to reconstruct its physical stratigraphy and to discuss how subsoil heterogeneities control the 1D and 2D local seismic response in such a volcanic setting. We first introduce a new multidisciplinary dataset, including geological (fieldwork and log from a 45-m-thick continuous coring borehole), geophysical (electrical resistivity tomographies, single station noise measurements, and 2D passive seismic arrays), and geotechnical (simple shear tests performed on undisturbed samples) approaches. Then, we reconstruct the subsoil model for the Stracciacappa maar in terms of vertical setting and distribution of its mechanical lithotypes, which we investigate for 1D and 2D finite element site response analyses through the application of two different seismic scenarios: a volcanic event and a tectonic event. The numerical modelling documents a significant ground motion amplification (in the 1–1.5 Hz range) revealed for both seismic scenarios, with a maximum within the centre of the maar. The ground motion amplification is related to both 1D and 2D phenomena including lithological heterogeneity within the upper part of the maar section and interaction of direct S-waves with Rayleigh waves generated at edges of the most superficial lithotypes. Finally, we use these insights to associate the expected distribution of ground motion amplification with the physical stratigraphy of an explosive volcanic setting, with insights for seismic microzonation studies and local seismic response assessment in populated environments.

This paper presents an overview of the geophysical activities for the seismic microzonation of 138 municipalities belonging to four Italian regions (Abruzzo, Lazio, Marche and Umbria) that were severely damaged by the seismic sequence of Central Italy (August 2016–January 2017). This study is the result of a collaborative effort between research Institutions and professional geologists with the support of local Administrations and the Italian Civil Protection Department and sets an unprecedented large-scale example of geophysical investigations supporting detailed seismic microzonation studies. This manuscript presents the methodological approach adopted for the geophysical activities, including the technical protocols and procedures, the best practices, the final products and the results supporting a detailed microzonation study of III level. The first step of the study was the collection and critical review of all available geophysical and geological information for planning the new geophysical surveys (specifically their type and location), in order to assess the subsoil geometry and the seismic characterization of the areas under investigation. Integration with the newly acquired geophysical data allowed the identification of zones with homogeneous local seismic hazard as well as the reference seismo-stratigraphy for each area, defining for each geological unit the ranges of the relevant properties in seismic amplification studies: layering and thicknesses, density, P-wave and S-wave seismic velocity. We also present a few representative case studies illustrating the geophysical investigation for different geomorphological situations. These examples, together with the findings of the entire project, are discussed to point out the strength points and the criticalities, as well as the necessary requirements in the application of geophysical methods to detailed microzonation studies.

The global urbanization process, along with the environmental impacts it carries with it, requires the adoption of innovative programming strategies for the sustainable and efficient management of natural resources and to improve the resilience of cities to natural disasters. In this scenario where the acquisition of a deeper and as thorough as possible knowledge of the territory on the problems connected with the phenomena of hydrogeological instability and natural risk in general that can affect the inhabited centers pose new challenges both at the level of government and for the scientific community. Further, it is also important to organize and make these complex information easily accessible to stakeholders, i.e. administrators, planners and civil protection. In the framework of two national projects, CLARA (CLoud plAtform and smart underground imaging for natural Risk Assessment) and SPOT (Development of a Platform for the provision of innovative services based on Earth Observation data), a systemic approach based on the integration of the latest enabling technologies (remote sensing and ground-based, active and passive, direct and indirect, multi-sources and multi-resolution) for the geo-physical characterization (seismic and electromagnetic) of the surface and near-surface and for the dynamic characterization of soil structure/infrastructure interactions was applied in the urban area of the city of Matera (southern Italy). By adopting the open-government and open-data paradigms, all the information collected have been eventually organized and shared in a web-gis along with geospatial data already available on different and independent web-services of local government authorities (region and municipality).

On 25 and 29 January 2019, a large landslide destroyed an important part of the town of Pomarico (Basilicata Region, Southern Italy). Geological and geomorphological investigations provided a detailed description of the landslide features. Several geophysical surveys were carried out to deepen knowledge of the landslide and the residual risk assessment. Detailed electrical resistivity tomography (ERT), multichannel analysis of surface waves (MASW), and seismic refraction tomography (SRT) have been used to analyze geomorphological evidences of the failure and the potential kinematic evolution of the landslide scarp, a crucial factor to assess landslide residual risk. The joint analyses of the geophysical results, compared with geological and geomorphological data, allowed to obtain detailed information about the stratigraphic contact between clayey and sandy deposits in the crown area of the landslide, and to identify the post-failure stability condition changes in sands. The geophysical analyses confirmed the presence of multiple old degraded scarps developed over time and provided information on the decompression state of the different areas of the landslide crown. The results highlighted a subparallel stratification consisting of an anthropic surface carry-over material, which covers a layer of sands with silty intercalations, overlying clayey material that represents the bedrock of the investigated area. Furthermore, natural and anthropogenic caves, mainly developed in well-cemented layers of sands, were identified. This study emphasized how the integration of different geophysical methods constitutes a capable tool for characterizing landslides, contributing to assessing the landslide residual risk of the slope mass and evaluating the suitability of the methods in relation to the investigated landslide conditions.

Landslides represent a major geomorphological feature influencing the evolution of the southern Apennine slopes with earth flows being one of the most representative types of landslide. The development of earth flows in the southern Apennines is facilitated by the widespread occurrence of clayey lithologies. Earth flows can either produce marked scars along the slopes, when their activity is high, or give rise to bumpy areas that are frequently covered by vegetation, when their activity is low. In this latter case, although the risk is significantly reduced, the earth flow can still represent a problem for buildings and infrastructure. The Picerno earth flow in the Basilicata region is an example of a low-activity earth flow. This NW-SE–oriented landslide extends for a length of ~ 5.5 km, has an average width of ~ 680 m, and affects the village of Picerno. Our investigations mainly focused on the terminal portion of the landslide and revealed that some significant linear infrastructures (e.g., the Potenza–Naples railway) and important provincial and municipal roads are affected by the earth flow. In order to better define the amount of displacement characterizing the Picerno earth flow and gain insights into the lateral extension and the depth of the main detachment surface, we undertook a detailed geological and geomorphological survey. Interferometry synthetic aperture radar data provided by the processing of SAR images, with the aim of highlighting the regions of the landslide that are currently active, together with electrical resistivity tomography data which have been utilized to define the geometry of the landslide body. Our results provide useful suggestions for planning appropriate actions aimed at stabilizing the landslide body.

The role of applied geophysics for the new scenario of the increasing global urbanization is going to grow day by day. In this scenario a detailed knowledge of the geological subsoil and its iteration with urban infrastructures became a fundamental issue for urban planning. A novel sub-discipline, called Urban Geophysics (Lapenna, 2017) , has recently been developing in the field of geophysics for analyzing limits and potentialities of well-known geophysical techniques in urban and industrialized areas. The application of some geophysical methods allows the recognition of geological structures from near surface down to more several hundred meters. The urban environment, characterized by a difficult logistic and a high level of noise, has a strong impact on the applicability of the geophysical prospecting methods and on the data quality. This paper presents the results obtained by Deep Electrical Resistivity Tomography (DERT) and P-wave seismic reflection surveys performed in the city of Ferrara, which is interested in the management of geothermal resources and in the mitigation of seismic risk (CLARA-“Cloud Platform and smart underground imaging for natural risk assessment” Project funded by Italian MIUR). Along the eastern flank of the city walls, DERT and Reflection Seismic profiles were carried out in order to improve the geological information of the urban context. DERT applications are not very common and there are only few published examples. It consists to inject direct current (square wave) into the ground, depending on the arrangement of the input points and the electrical resistivity of the subsoil, the shape of the electric field that is measured at the surface. The peculiarity of the DERT is the use of large electrode distances (>200 m) and long profiles (>3000 m) in order to reach large investigation depths (>300 m). Seismic reflection investigations offer a powerful non‐invasive tool suitable for mapping the subsurface geological framework from the very near‐surface to hundreds of metres below surface. Recently several seismic surveys was performed in urban environment by using frequency-controlled vibroseis sources both in P- and SH-wave. Along the eastern flank of the city walls, a DERT (5500m long) and a reflection seismic (2500m acquired by a MiniVib source in P-wave configuration) profiles were carried out in order to improve the geological information of the urban context. The joint interpretation of DERT and seismic data allowed to reconstruct the 'local' stratigraphic-depositional evolution until a depth of about 1 km, and to highlight the occurrence of a sin-depositional Quaternary tectonic tilting associated to the growth of a fault-propagation fold.

This paper deals with a geophysical survey carried out in some critical urban areas of the historical city of Matera (Southern Italy). Matera has a very complex shallower stratigraphy characterized by both anthropic and natural “targets” and is affected by geological instability. Therefore, Matera represents an ideal and very challenging outdoor laboratory for testing novel approaches for near-surface explorations in urban areas. Here, we present the results of a near-surface survey carried out by jointly applying Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) methods. The survey was implemented in three different critical zones within the urban area of Matera (Piazza Duomo, Piazza San Giovanni, Villa dell’Unità d’Italia). These test sites are of great interest for archaeological and architectonical studies and are affected by ground instability phenomena due to the presence of voids, cavities and other anthropic structures. The effectiveness of the survey was enhanced by the exploitation of advanced 3D tomographic approaches, which allowed to achieve 3D representation of the investigated underground and obtain information in terms of both the location and the geometry of buried objects and structures and the characterization of shallow geological layers. The results of the surveys are now under study (or have attracted the interest) of the Municipality in order to support smart cities programs and activities for a better management of the underground space.

A multidisciplinary approach based on the integration of geological and in situ geophysical techniques was applied to investigate the Orvieto Cathedral (Umbria, Central Italy) and the underlying subsurface. Notwithstanding this Cathedral has successfully survived different earthquakes occurred in the region, it shows some signs of damage that arise uncertainties about its safety under future seismic events. In order to investigate its unknown foundation geometry, to reconstruct the geological setting and to characterize from a static and dynamic point of view the site-structure system, geological investigations together with electrical resistivity tomography and horizontal-to-vertical spectral ratio analysis of single-station ambient vibration recordings were carried out. The exploitation of these two different geophysical techniques allowed us (1) to delineate the unknown foundation geometry of the Orvieto Cathedral, (2) to estimate the main resonance frequencies of the Cathedral and (3) of the Orvieto site, and (4) to retrieve information about its deep subsurface engineering-geological structure.

The Brindisi di Montagna Scalo Landslide in Southern Italy is an active complex mass movement, which affects the left slope of the Basento River. In the last few decades, this landslide has been continuously monitored, as it directly threatened some of the most important communication routes in the Basilicata Region. Nevertheless, little progresses have been made to prevent further landslide advancement, and continuous maintenance is required. With the aims of better understanding, the main factors controlling the evolution of this landslide, and suggesting the most appropriate countermeasures, a multidisciplinary study, based on the integration of direct and indirect techniques, was carried out. Direct techniques included multi-temporal geomorphological analysis of the slope, alongside geological and structural field observations. Indirect techniques consisted of electrical resistivity tomography acquisition. The combined analyses of the geological and geophysical data showed that Quaternary tectonic processes played a fundamental role as a predisposing factor, whereas seasonal rainfall, and the perpetual undercutting by erosional processes caused by the Basento River at the toe of the landslide are the main triggering mechanisms. The Brindisi di Montagna Scalo Landslide represents an outstanding case-study, concerning the interaction between a flow-like complex landslide and essential linear infrastructure, such as motorways and railways.

A multidisciplinary approach based on the integration of in situ geophysical and geological techniques was applied to investigate the Orvieto Cathedral (Umbria Region, Central Italy) and the subsurface. In particular, the electrical resistivity tomography and the horizontal to vertical spectral ratio analysis of single station ambient vibrations measurements were used. This paper reports the results obtained with the joint analysis of the in situ geophysical investigations, geological field survey and borehole data. The joint analysis of different data allowed us (1) to image the geological setting, (2) to highlight some resonance frequencies of the monumental building, and (3) to estimate the resonance frequency of the site.