Search Results (14)

Urban expansion in coastal areas involves infrastructure development, industrial growth, and mining activities. These coastal environments face various environmental and geological hazards that require geo-engineers to devise solutions. An integrated geophysical approach aims to address such complex challenges as sea level rise, sea water intrusion, shoreline erosion, landslides and previous anthropogenic activity in coastal settings. In this study, the proposed methodology involves the systematic application of geophysical methods (FDEM, 3D GPR, 3D ERT, seismic), starting with a broad-scale survey and then proceeding to a localized exploration, in order to identify lithostratigraphy, bedrock depth, sea water intrusion and detect anthropogenic buried features. The critical aspect is to leverage the unique strengths and limitations of each method within the coastal environment, so as to derive valuable insights for survey design (extension and orientation of measurements) and data interpretation. The coastal zone of Throrikos valley, Attica, Greece, serves as the test site of our geophysical investigation methodology. The planning of the geophysical survey included three phases: The application of frequency-domain electromagnetic (FDEM) and 3D ground penetrating radar (GPR) methods followed by a 3D electrical resistivity tomography (ERT) survey and finally, using the seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW). The FDEM method confirmed the geomorphological study findings by revealing the paleo-coastline, superficial layers of coarse material deposits and sea water preferential flow due to the presence of anthropogenic buried features. Subsequently, the 3D GPR survey was able to offer greater detail in detecting the remains of an old marble pier inland and top layer relief of coarse material deposits. The 3D ERT measurements, deployed in a U-shaped grid, successfully identified the anthropogenic feature, mapped sea water intrusion, and revealed possible impermeable formation connected to the bedrock. ERT results cannot clearly discriminate between limestone or deposits, as sea water intrusion lowers resistivity values in both formations. Finally, SRT, in combination with MASW, clearly resolves this dilemma identifying the lithostratigraphy and bedrock top relief. The findings provide critical input for engineering decisions related to foundation planning, construction feasibility, and preservation of coastal infrastructure. The methodology supports risk-informed design and sustainable development in areas with both natural and cultural heritage sensitivity. The applied approach aims to provide a complete information package to the modern engineer when faced with specific challenges in coastal settings. Full article

The paper presents a case study on the impact of a shallow landslide in overconsolidated clays, which was triggered during the winter of 2004–2005 due to exceptionally high pore pressures, on the operativity and serviceability of a key road artery in Sicily. During the period from 2004 to 2021, the landslide experienced several reactivations, particularly during the winter months when increased rainfall led to rising pore water pressures. These recurrent events resulted in temporary road closures and continuous restoration efforts, causing significant inconvenience for local communities and substantial economic losses for commercial, tourism, and agricultural activities in the area. In 2018, a comprehensive study was launched to reconstruct the detailed geotechnical model of the landslide, analysing its mechanical and kinematic characteristics, pore pressure regime, the depth and geometry of the sliding surface, and the causes of the landslide. The study indicates that the primary causes of both the initial landslide and its subsequent reactivations were the poor mechanical properties of the involved soils and seasonal fluctuations in pore water pressures. To ensure long-term stabilisation, the most suitable interventions were identified as the permanent reduction of pore pressures through the installation of drainage trenches and the construction of a road embankment using gabions, which also serve as drainage structures. These measures are highly effective, relatively cost-efficient, easy to implement, and environmentally sustainable. Full article

The Jacotines landslide is representative of the large mass movements that affect the Champagne vineyards. Understanding the subsurface structure of these slopes and the mechanisms leading to sliding events is of a great interest, particularly for winegrowers who produce Champagne. This knowledge is generally used to elaborate accurate hazard assessment maps, which is an important feature in land use planning. The approach presented is based on the integration of geophysical imaging (seismic wave velocity and electrical resistivity), lithostratigraphic analysis (drilling core) and geomorphological investigations (surface landforms) to reconstruct the relations between the landslide structure, surface water flow, groundwater regime and the overall slope stability. A first phase of instability resulting in a large rotational slip probably occurred during the Late Glacial Period in morphoclimatic conditions characterized by an excess of water. A second one, still active, leading to superficial reactivations and relates to present hydrogeological conditions determined by the internal structure of the landslide. Full article

Site effects refer to the modification of ground shaking caused by the local geological conditions that can result in the strong amplification of ground motion. The best-known cause for site effects is the presence of superficial soft soil deposits, which are considered in seismic design codes of many countries through the use of scaling factors. Rock sites are assumed to show no local site amplification. However, even at rock sites, seismic waves can be locally amplified at frequencies of engineering interest, with larger motion along one site-specific azimuth on the horizontal plane (the so called “directional site resonance or amplification”). These effects have been related to the presence of large-scale open cracks or microcracks in different geological environments (faults, landslides, volcanic areas) everywhere with a common signature: maximum amplification occurs transverse to the predominant fracture strike. In this paper, we summarize our main results obtained in the last decade with regard to several fault zones with different kinematics, where ground motion is polarized (and amplified) perpendicularly to the predominant fracture field as an effect of the stiffness anisotropy. In order to give a further constraint, we also show some cases where the directional amplification effects were compared with the S-wave splitting analysis method. Full article

This work is based on a drainage basin-scale geomorphological investigation combined with flood modeling. It is focused on the assessment of flood critical areas for the implementation of a geomorphology-based urban Early Warning System (EWS) in the urban area of Lanciano and the Feltrino Stream basin (a minor coastal basin of the Abruzzo hills, Central Italy). This area was investigated by combining: pre-existing geological, geomorphological, and hazard data and new detailed field surveys and mapping of geomorphological and hydrographical features (superficial and buried natural and urban stream network). The study was integrated with 2D flood numerical modeling for verifying the expected flooded areas and calibrating the critical areas. All the collected data were integrated into a geodatabase, and an expert-based approach through a geomorphology-based matrix allowed us to define the main categories of flood critical areas. The assessment of the critical areas supported the emplacement of a network of rainfall, temperature, and flood gauges. The geodatabase, the derived critical areas, and the gauge network contributed to set up an urban EWS, integrated with the regional forecast-based warning system. This system provides combined forecast-based, rainfall threshold-based, and flood monitoring-based alerts for floods. It incorporates communication tools for civil protection management. Finally, the EWS provides a tool for civil protection purposes and for the management of flood critical areas and the mitigation of the related risks by local authorities and will be integrated with sensors related to other hazards (i.e., landslides, wind, etc.). Full article

In Zaruma city, located in the El Oro province, Ecuador, gold mines have been exploited since before the colonial period. According to the chroniclers of that time, 2700 tons of gold were sent to Spain. This exploitation continued in the colonial, republican, and current periods. The legalized mining operation, with foreign companies such as South Development Company (SADCO) and national companies such as the Associated Industrial Mining Company (CIMA), exploited the mines legally until they dissolved and gave rise to small associations, artisanal mining, and, with them, illegal mining. Illegal underground mining is generated without order and technical direction, and cuts mineralized veins in andesitic rocks, volcanic breccia, tuffs and dacitic porphyry that have been intensely weatherized from surface to more than 80 meters depth. These rocks have become totally altered soils and saprolites, which have caused the destabilization of the mining galleries and the superficial collapse of the topographic relief. The illegal miners, called "Sableros", after a period of exploitation at one site, when the gold grade decreased, abandon these illegal mines to begin other mining work at other sites near mineralized veins or near legalized mining galleries in operation. Due to this anthropic activity of illegal exploitation through the mining galleries and “piques” that remain under the colonial center of the city, sinkings have occurred in various sectors detected and reported in various technical reports since 1995. The Ecuadorian Government has been unable to control these illegal mining activities. The indicators of initial subsidence of the terrain are small movements that accumulate over a time and that can be detected with InSAR technology in large areas, improving the traditional detection performed with geodetic instrumentation such as total stations and geodetic marks. Recent subsidence at Fe y Alegría-La Immaculada School, the city’s hospital and Gonzalo Pizarro Street, indicates that there is active subsidence in these and other sectors of the city. The dynamic triggers that have possibly accelerated the rate of subsidence and landslides on the slopes are earthquakes (5 to 6 Mw) and heavy rains in deforested areas. Although several sinks and active subsidence caused by underground mining were detected in these sectors and in other sectors in previous decades, which were detailed in various reports of geological hazards prepared by specialized institutions, underground mining has continued under the colonial city center. In view of the existing risk, this article presents a forecasting methodology for the constant monitoring of long-term soil subsidence, especially in the center of the colonial city, which is a national cultural heritage and candidate for the cultural heritage of humanity. This is a proposal for the use of synthetic aperture radar interferometry (InSAR) for the subsidence analysis of topographic relief in the colonial area of the city of Zaruma by illegal mining galleries. Full article

Central Asian mountain regions are prone to multiple types of natural hazards, often causing damage due to the impact of mass movements. In spring 2017, Kyrgyzstan suffered significant losses from a massive landslide activation event, during which also two of the largest deep-seated mass movements of the former mining area of Mailuu-Suu—the Koytash and Tektonik landslides—were reactivated. This study consists of the use of optical and radar satellite data to highlight deformation zones and identify displacements prior to the collapse of Koytash and to the more superficial deformation on Tektonik. Especially for the first one, the comparison of Digital Elevation Models of 2011 and 2017 (respectively, satellite and unmanned aerial vehicle (UAV) imagery-based) highlights areas of depletion and accumulation, in the scarp and near the toe, respectively. The Differential Synthetic Aperture Radar Interferometry analysis identified slow displacements during the months preceding the reactivation in April 2017, indicating the long-term sliding activity of Koytash and Tektonik. This was confirmed by the computation of deformation time series, showing a positive velocity anomaly on the upper part of both landslides. Furthermore, the analysis of the Normalized Difference Vegetation Index revealed land cover changes associated with the sliding process between June 2016 and October 2017. In addition, in situ data from a local meteorological station highlighted the important contribution of precipitation as a trigger of the collapse. The multidirectional approach used in this study demonstrated the efficiency of applying multiple remote sensing techniques, combined with a meteorological analysis, to identify triggering factors and monitor the activity of landslides. Full article

Cultivation of grapevines in sloping soils is very widespread all over the world, representing also a fundamental branch of the local economy of several hilly zones. Vineyards can be managed in different ways especially the inter-rows. These management practices may influence deeply soil properties and grapevine root development. Therefore, this work aims to analyze the effects of different agronomical practices of inter-rows on soil properties, grapevine root systems and proneness towards shallow landslides. We focused on traditional agricultural techniques of tillage and permanent grass cover as well as the alternation of these two practices between adjacent inter-rows. The studied parameters were: (i) soil physical and hydrological properties; (ii) soil biodiversity; (iii) root density; (iv) root mechanical properties and root reinforcement; (v) probability of occurrence of shallow landslides. The research was conducted in several test-sites of the Oltrepò Pavese (Lombardy region, north-western Italy), one of the most important Italian zones for wine production in northern Italian Apennines. Among the examined soil properties, soil hydraulic conductivity was the most influenced one by different soil management practices. The absence of soil tillage allowed to increase superficial (first 0.2 m of soil) hydraulic conductivity, as a consequence of higher macroporosity and amount in organic matter. Within the soil biological features, soil microarthropod communities showed more complexity where permanent grass cover or alternation management of the inter-rows were applied. Regarding the features of the grapevine root system, vineyards with alternation management of inter-rows had the highest root density and the strongest root reinforcement, of up to 45% in comparison to permanent grass cover, and up to 67–73% in comparison to tilled vineyards. As a consequence, slopes with medium steepness (10–18°) were unstable if inter-rows of vineyards were tilled, while vineyards with permanent grass cover or alternation in the inter rows promoted the stability of slopes with higher steepness (> 21–25° for vineyards with permanent grass cover in the inter rows, 28–33° for vineyards with alternation). The results of this study yielded important information to establish effective management practices of vineyards such as conserving organic matter and reducing slope instabilities by a better development of the root apparatus. Possible land use managements acting as mitigation measures for shallow landslides susceptibility could be also implemented. This work was supported by the project Oltrepò BioDiverso, funded by Fondazione Cariplo in the frame of AttivAree Program. Full article

We investigated the role of the morphostructural setting and seismic and meteorological factors in the development of landslides in the piedmont of the Abruzzo Apennines. In February 2017, following a heavy snow precipitation event and a moderate seismic sequence (at the end of the Central Italy 2016–2017 seismic crisis), several landslides affected the NE-Abruzzo chain and piedmont area. This work is focused on the Ponzano landslide (Civitella del Tronto, Teramo) and the Castelnuovo landslide (Campli, Teramo) in the NE Abruzzo hilly piedmont. These landslides consist of: (1) a large translational slide-complex landslide, affecting the Miocene–Pliocene sandstone clay bedrock sequence of the piedmont hilly sector; and (2) a complex (topple/fall-slide) landslide, which occurred along a high and steep scarp on conglomerate rocks pertaining to terraced alluvial fan deposits of the Pleistocene superficial deposits. Both of the landslides are typical of the Abruzzo hilly piedmont and both of them largely affected houses and villages located on top of the scarp or within the slope. The landslides were studied by means of field geological and geomorphological mapping, borehole investigations, geostructural analysis and photogeological analysis. For the Ponzano landslide, a detail pre-post-landslide air photo interpretation allowed for defining the deformation pattern occurred on the slope. For the Castelnuovo landslide, the triggering factors and the stability of the slope were evaluated with FLAC3D numerical modelling, in pre- and post-landslide conditions. Through this integrated analysis, the triggering factors, the landslide mechanism and the stability conditions of the landslides and the characterization of two main types of landslides affecting the piedmont hilly area of the Abruzzo region were investigated. Full article

Mass movements in deformed areas of natural relief deformed by seismotectonic factors are one of the most destructive and recurrent natural hazards in the Republic of Ecuador, especially during intense rain periods, the El Niño phenomenon, or due to earthquakes such as the one that occurred on 16 April 2016 in the Ecuadorian coastline. This study proposes the application of Hydrological Model D8 and its derived morphometric parameters like slope, orientation of the slope, and curvatures, extracted from the high spatial resolution Digital Elevation Model (DEM), implemented in programs such as Rockworks 7 (gridzo), SURFER (downwards slope), ArcView (flowacc), and SAGA (curvatures) to obtain runoff flow, structural geological lineaments, and superficial deformations of the topographic relief that are the origin of erosion, superficial landslides, lateral propagation, of the rock–soil complex, mass flows, and deep gravitational deformations. This methodology has been validated in three locations with intense deformations: two in Ecuador and one in Spain. The DEM were obtained from the Ecuadorian Spatial Institute (ESI) (spatial resolution of 10 m), the Rural Technological Infrastructure and Information National System (SIGTIERRAS) (spatial resolution of 5 m), and the Council of Andalusia (spatial resolution of 5 m). Full article

An innovative wireless sensor network (WSN) based on Ultra-Wide Band (UWB) technology for 3D accurate superficial monitoring of ground deformations, as landslides and subsidence, is proposed. The system has been designed and developed as part of an European Life+ project, called Wi-GIM (Wireless Sensor Network for Ground Instability Monitoring). The details of the architecture, the localization via wireless technology and data processing protocols are described. The flexibility and accuracy achieved by the UWB two-way ranging technique is analysed and compared with the traditional systems, such as robotic total stations (RTSs) and Ground-based Interferometric Synthetic Aperture Radar (GB-InSAR), highlighting the pros and cons of the UWB solution to detect the surface movements. An extensive field trial campaign allows the validation of the system and the analysis of its sensitivity to different factors (e.g., sensor nodes inter-visibility, effects of the temperature, etc.). The Wi-GIM system represents a promising solution for landslide monitoring and it can be adopted in combination with traditional systems or as an alternative in areas where the available resources are inadequate. The versatility, easy/fast deployment and cost-effectiveness, together with good accuracy, make the Wi-GIM system a possible solution for municipalities that cannot afford expensive/complex systems to monitor potential landslides in their territory. Full article

Owing to the development of spaceborne synthetic aperture radar (SAR) platforms, and in particular the increase in the availability of multi-source (multi-band and multi-resolution) data, it is now feasible to design a surface displacement monitoring application using multi-temporal SAR interferometry (MT-InSAR). Landslides have high socio-economic impacts in many countries because of potential geo-hazards and heavy casualties. In this study, taking into account the merits of ALOS PALSAR (L-band, good coherence preservation) and TerraSAR (X-band, high resolution and short revisit times) data, we applied an improved small baseline InSAR (SB-InSAR) with 3-D phase unwrapping approach, to monitor slope superficial displacement in Hong Kong, China, a mountainous subtropical zone city influenced by over-urbanization and heavy monsoonal rains. Results revealed that the synergistic use of PALSAR and TerraSAR data produces different outcomes in relation to data reliability and spatial-temporal resolution, and hence could be of significant value for a comprehensive understanding and monitoring of unstable slopes. Full article

The slow movement of active deep-seated slope gravitational deformations (DSGSDs) and deep-seated rockslides can cause damage to structures and infrastructures. We use Permanent Scatterers Synthetic Aperture Radar Interferometry (PSInSAR™) displacement rate data for the analysis of DSGSD/rockslide activity and kinematics and for the analysis of damage to buildings. We surveyed the degree of damage to buildings directly in the field, and we tried to correlate it with the superficial displacement rate obtained by the PSInSAR™ technique at seven sites. Overall, we observe that the degree of damage increases with increasing displacement rate, but this trend shows a large dispersion that can be due to different causes, including: the uncertainty in the attribution of the degree of damage for buildings presenting wall coatings; the complexity of the deformation for large phenomena with different materials and subjected to differential behavior within the displaced mass; the absence of differential superficial movements in buildings, due to the large size of the investigated phenomena; and the different types of buildings and their position along the slope or relative to landslide portions. Full article

: The measurement of landslide superficial displacement often represents the most effective method for defining its behavior, allowing one to observe the relationship with triggering factors and to assess the effectiveness of the mitigation measures. Persistent Scatterer Interferometry (PSI) represents a powerful tool to measure landslide displacement, as it offers a synoptic view that can be repeated at different time intervals and at various scales. In many cases, PSI data are integrated with in situ monitoring instrumentation, since the joint use of satellite and ground-based data facilitates the geological interpretation of a landslide and allows a better understanding of landslide geometry and kinematics. In this work, PSI interferometry and conventional ground-based monitoring techniques have been used to characterize and to monitor the Santo Stefano d’Aveto landslide located in the Northern Apennines, Italy. This landslide can be defined as an earth rotational slide. PSI analysis has contributed to a more in-depth investigation of the phenomenon. In particular, PSI measurements have allowed better redefining of the boundaries of the landslide and the state of activity, while the time series analysis has permitted better understanding of the deformation pattern and its relation with the causes of the landslide itself. The integration of ground-based monitoring data and PSI data have provided sound results for landslide characterization. The punctual information deriving from inclinometers can help in defining the actual location of the sliding surface and the involved volumes, while the measuring of pore water pressure conditions or water table level can suggest a correlation between the deformation patterns and the triggering factors. Full article