1,721,013 research outputs found
Infrared thermographic surveys for landslide mapping and characterization: the Rotolon DSGSD (Norther Italy) case study
No full textOn November 4th 2010, after several days of intense rainfall, a huge mass (about 225000 m3) detached from the debris cover of the Rotolon landslide, converging within the Rotolon Creek river bed, and evolving into a mobile debris flow that damaged various infrastructures, putting on high risk three villages located along the creek banks. After this event the National Department of Civil Protection (DPCN) appointed the Earth Sciences Department of the Firenze University (DST-UNIFI) to start a GB-InSAR (ground based interferometric synthetic aperture radar) monitoring activity, in order to support the local authorities for the emergency management by analyzing the landslide displacements and evaluating the residual risk. During this phase accurate geomorphological and infrared thermographic (IRT) surveys were also carried out, in order to study the landslide morphological features, with the aim of improving the radar displacement data interpretation. The obtained geomorphological map suggests that the debris production and detachment are hazardous phenomena that involve the surficial detrital cover of a bigger and more complex landslide. The latter has the characteristics of a deep seated gravitational slope deformation (DSGDS)
Landslide mapping and characterization through Infrared Thermography (IRT): Suggestions for a methodological approach from some case studies
No full textIn this paper, the potential of Infrared Thermography (IRT) as a novel operational tool for landslide surveying, mapping and characterization was tested and demonstrated in different case studies, by analyzing various types of instability processes (rock slide/fall, roto-translational slide-flow). In particular, IRT was applied, both from terrestrial and airborne platforms, in an integrated methodology with other geomatcs methods, such as terrestrial laser scanning (TLS) and global positioning systems (GPS), for the detection and mapping of landslides’ potentially hazardous structural and morphological features (structural discontinuities and open fractures, scarps, seepage and moisture zones, landslide drainage network and ponds). Depending on the study areas’ hazard context, the collected remotely sensed data were validated through field inspections, with the purpose of studying and verifying the causes of mass movements. The challenge of this work is to go beyond the current state of the art of IRT in landslide studies, with the aim of improving and extending the investigative capacity of the analyzed technique, in the framework of a growing demand for effective Civil Protection procedures in landslide geo-hydrological disaster managing activities. The proposed methodology proved to be an effective tool for landslide analysis, especially in the field of emergency management, when it is often necessary to gather all the required information in dangerous environments as fast as possible, to be used for the planning of mitigation measures and the evaluation of hazardous scenarios. Advantages and limitations of the proposed method in the field of the explored applications were evaluated, as well as general operative recommendations and future perspectives
GB-InSAR monitoring of slope deformations in a mountainous area affected by debris flow events
No full textDiffuse and severe slope instabilities affected the whole Veneto region (north-eastern Italy) between 31 October and 2 November 2010, following a period of heavy and persistent rainfall. In this context, on 4 November 2010 a large detrital mass detached from the cover of the Mt. Rotolon deep-seated gravitational slope deformation (DSGSD), located in the upper Agno River valley, channelizing within the Rotolon Creek riverbed and evolving into a highly mobile debris flow. The latter phenomena damaged many hydraulic works, also threatening bridges, local roads, and the residents of the Maltaure, Turcati, and Parlati villages located along the creek banks and the town of Recoaro Terme. From the beginning of the emergency phase, the civil protection system was activated, involving the National Civil Protection Department, Veneto Region, and local administrations' personnel and technicians, as well as scientific institutions. On 8 December 2010 a local-scale monitoring system, based on a ground-based interferometric synthetic aperture radar (GB-InSAR), was implemented in order to evaluate the slope deformation pattern evolution in correspondence of the debris flow detachment sector, with the final aim of assessing the landslide residual risk and managing the emergency phase. This paper describes the results of a 2-year GB-InSAR monitoring campaign (December 2010–December 2012) and its application for monitoring, mapping, and emergency management activities in order to provide a rapid and easy communication of the results to the involved technicians and civil protection personnel, for a better understanding of the landslide phenomena and the decision-making process in a critical landslide scenario
Emergency management of the 2010 Mt. Rotolon landslide by means of a local scale GB-InSAR monitoring system
No full textBetween October 31st and November 2nd 2010 the whole Veneto region (north-eastern Italy) was hit by heavy and persistent rainfall, which diffusely triggered floods and slope failures. In this framework on November 4th 2010 a detrital mass, approximately 225.000 m3 in volume, detached from the lowermost sector of the Mt. Rotolon landslide cover (located in the Vicentine Pre-Alps, upper Agno River Valley), channelizing within the Rotolon Creek riverbed and evolving into a highly mobile debris flow. The latter phenomena, characterized by a 3 km travel distance, damaged many hydraulic works, putting at high risk bridges and local roads located along the creek banks, together with the population of both the town of Recoaro Terme and the villages of Maltaure, Turcati and Parlati. Starting from the beginning of the emergency phase, the Civil Protection system was activated, involving the National Civil Protection Department, Veneto Region and local administrations personnel and technicians, as well as research centers. On December 8th 2010 a local scale monitoring system, based on a ground based interferometric radar (GB-InSAR), was implemented in order to evaluate the slope deformation pattern evolution in correspondence of the debris flow detachment sector, with the final aim of assessing the landslide residual risk and manage the emergency phase. Accurate geomorphological field surveys were also carried out, in order to study the landslide morphological features as to improve the radar data interpretation. The radar system acquired in continuous GB-InSAR data, such as displacement maps and time series of 10 selected monitoring points, which were uploaded via LAN network on a dedicated Web-based interface, shared with the technical stakeholders and decision makers involved in the emergency management and allowing for a near real time data routine visualization. This paper describes the outcomes of a 2 years GB-InSAR monitoring campaign (December 2010-November 2012), reporting the various applications of GB-InSAR data for monitoring, mapping and emergency management activities, in order to provide a rapid and easy communication of the results to the involved technicians and civil protection personnel, for a better understanding of the landslide phenomena and decision making process in a critical landslide scenario
Geomorphology of the Rotolon landslide (Veneto Region, Italy)
No full textIn this paper a geomorphological map of the Rotolon landslide is presented. This cartographic product was obtained using a combination of accurate field surveys together with airborne Lidar analysis, aerial photo interpretation and thermographic field surveys within a GIS. The map was prepared in order to analyze the morphological features of the landslide and therefore improve interpretation of the GB-InSAR data. This monitoring device was installed on the site after the detachment of a debris mass of 225,000 m3 on 4 November 2010. The main purpose of the post-event activities, including the geomorphological characterization, was to detect the processes acting on the landslide, evaluate the hazard related to each phenomenon, understand the landslide kinematics and define the residual risk for the area.The geomorphological map suggests that debris production and detachment are hazardous phenomena that involve the surficial detrital cover of a bigger and more complex landslide. The latter has the typical characteristics of a deep-seated gravitational slope deformation. The distinction between secondary processes, which appear to be the most hazardous in the short-term, and deep seated ones, demonstrates that accurate mapping provides important information for local administrations and decision makers, allowing them to prepare landslide susceptibility and hazard models
Geomorphological characterization, monitoring and modeling of the Monte Rotolon complex landslide (Recoaro Terme, Italy)
No full textThe Rotolon landslide, located in the upper Agno River valley (Vicenza, Italy), has threatened the valley for centuries. During November 2010, after 637 mm of rainfall in 12 days, a debris mass of about 225,000 m3 collapsed from the lowermost portion of the landslide and evolved into a debris flow that channeled in the Rotolon Creek riverbed, damaging the villages of Maltaure and Parlati in the Recoaro Terme municipality. On December 8th, 2010 the Department of Earth Sciences of the University of Firenze started a real-time monitoring using a GB-InSAR radar interferometer. The radar data are elaborated to obtain weekly, monthly and total cumulated 3D displacement maps and displacement time series of ten control points selected on the landslide mass. Accurate field surveys were carried out to analyze the landslide physiographic features and to validate the ground deformation retrieved from the radar data. The geomorphological features, supported by the radar data, led to an interpretation of the complex Rotolon landslide as a Deep Seated Gravitational Slope Deformation, whose detrital cover is often affected by detachments triggering debris flows. The November 2010 detachment area was modeled in order to: (i) calculate the main geotechnical properties of the collapsed material by means of a back analysis; (ii) define the residual risk; (iii) simulate new critical scenarios for the new topographic slope surface
TXT-tool 2.039-3.2 Ground-based remote sensing techniques for landslides mapping, monitoring and early warning
No full textThe current availability of advanced remote sensing technologies in the field of landslide analysis allows rapid and easily updatable data acquisitions, improving the traditional capabilities of detection, mapping and monitoring, optimizing field work, and allowing to investigate hazardous and inaccessible areas while granting at the same time the safety of the operators. In the recent years in particular, ground-based remote sensing techniques have undergone a significant increase of usage, thanks to their technological development and quality data improvement, offering advantages with respect to air- or spaceborne remote sensing techniques, in terms of data spatial resolution and accuracy, fast measurement and processing times, and portability and cost-effectiveness of the acquiring instruments. These advantages can be highlighted in the framework of landslide emergency management, when it is often urgently necessary to minimize survey time when operating in dangerous environments and gather all the required information as fast as possible. In this paper, the potential of some ground-based remote sensing techniques and the effectiveness of their synergic use is explored in several case studies, analyzing different slope instability processes at different scales of emergency or post-emergency management. Thanks to them and to the support of existing bibliography, the most common fields of application are suggested for all the considered ground-based sensor technologies and their level of effectiveness is evaluated in relation to the dynamics of landslide types
Contribution of infrared thermography to the slope instability characterization
No full textInfrared thermography (IRT), or thermal imaging, is a remote sensing technique capable of mapping the surface temperature pattern evolution, leading to the detection of thermal anomalies within the investigated object. In recent years IRT has undergone a significant increase of applications, thanks to the technological development of portable and cost-effective thermal imaging cameras, as well as the fast measurement and processing times of thermographic data. Nevertheless in the study of slope instability processes, apart from a few interesting experimental studies, IRT is still not widely applied. In this paper we present some applications of IRT, both terrestrial and airborne, in attempt to contribute to a rapid high resolution mapping and to the characterization of slopes affected by instability phenomena. In particular IRT was employed in an integrated approach with other remote sensing techniques, such as terrestrial and aerial laser scanner and photography, in order to detect criticalities in unstable slopes and evaluate the possible hazardous scenarios in emergency management. The potential of IRT for landslide mapping and characterization was explored in different types of critical landscapes (from terrigenous/detrital slopes to rock walls) analyzing the following characteristics: i) pattern of the structural discontinuities and open fractures in rock slopes affected by rock sliding; ii) ephemeral springs and creeks in detrital covers recently affected by debris flow detachment; iii) scarps, moisture and water stagnation areas within large earth flows
Analysis of LiDAR derived DEM geomorphometric parameters to assess the kinematic behaviour of a DSGSD
No full textSlope instability processes in mountainous areas are characterized by a complex interaction between different lithological, geomorphological, structural features, and processes. Deep-seated gravitational slope deformations (DSGSDs) are largest non-catastrophic slow rock-slope deformation, that until recently, under the present climatic condition, were considered inactive and not hazardous phenomena. Generally, the entire slope affected by DSGSD can be differently deformed with millimetric-displacements, that often cannot be observed by means of field surveys. This can generate in the risk management of these phenomena non-exhaustive safety awareness strategies, which on the contrary often focus only on the more short-period localized hazardous effects. DSGSD, in fact, evolve at different time scales and could present sudden and rapid secondary minor landslides. Therefore, a complete risk assessment strategy must comprise also the analysis of deep-seated impulsive phenomena. This type of behaviour can be observed effectively only using high-resolution data obtained by means of advanced remote sensing techniques. Among all these technologies applied in landslide analysis the more effective in the DSGSD studies are: ground-based interferometric radar (GB-InSAR) and Light detection and ranging (LiDAR). On 4th November 2010, after the October-November 2010 rainfalls, the Rotolon deep-seated gravitational slope deformation (Vicentine Pre-Alps, NE Italy) reactivated with a sudden ground movement. A 450,000 m2 mountainous area moved some meter downslope, but the undeniable signs were only connected to the triggering of a debris flow from the bulging area detrital cover, and the presence of a continuous perimeter fracture near the crown area. Therefore, the 2010 event apparently was limited to secondary and localized phenomena, so that an early-warning system (a GB-InSAR and an automatic monitoring network composed by extensometers and a robotic total station) were installed to monitor the residual risk. Moreover, a 3D landslide runout numerical model was performed to identify the source and impact areas of further debris flow, the flow velocity, and the deposit distribution within the Rotolon creek valley. Nevertheless, the analysis of the DEMs parameters, derived from two detailed LiDAR surveys (2x2 m), performed just few days before and after the event, allowed to highlight some morphological changes occurred after the 2010 reactivation, and associable not only to shallow movements but also to deeper ones. The kinematic behavior reconstruction and the geomorphometric parameters analysis were performed in a GIS environment, integrating morphometric terrain parameters (slope, aspect, surface roughness, topographic wetness index, hillshade, and curvature) with the results of an accurate geomorphological field survey. This analysis pointed out not only shallower movements in the bulging area, but also regular morphological changes occurred in six main areas of the whole DSGSD, and connected to deeper continuous displacements along the maximum slope gradient, confirming the DSGSD reactivation. Moreover, the displacements connected to the DSGSD reactivation did not cease immediately, in particular far from the break/crown zone (as shown by the integration of the morphometric terrain parameters and the GB-InSAR data), but continued with very slow deformations until the new equilibrium was reached, testifying the impulsive behavior of the landslide
Kinematic reconstruction of a deep-seated gravitational slope deformation by geomorphic analyses
No full textOn 4 November 2010, a deep-seated gravitational slope deformation (North Italy) reactivated with sudden ground movement. A 450,000 m2 mountainous area moved some metres downslope, but the undeniable signs were only connected to the triggering of a debris flow from the bulging area’s detrital cover and the presence of a continuous perimeter fracture near the crown area. Based on two detailed LiDAR surveys (2 m × 2 m) performed just a few days before and after the event, a quantitative topographic analysis was performed in a GIS environment, integrating morphometric terrain parameters (slope, aspect, surface roughness, hill shade, and curvature). The DEMs analysis highlighted some morphological changes related to deeper as well as shallow movements. Both global and sectorial displacements were widely verified and discussed, finally inferring that the geometry, persistence, and layout of all movements properly justify each current morphostructure, which has the shape of a typical Sackung-type structure with impulsive kinematics. Moreover, a targeted field survey allowed specific clues to be found that confirmed the global deduced dynamics of the slope deformation. Finally, thanks to a ground-based interferometric radar system (GB-InSAR) that was installed a few days after the reactivation, the residual deep-seated gravitational slope deformation (DSGSD) movements were also monitored. In the landslide lower bulging area, a localized material progression of small entities was observed for some months after the parossistic event, indicating a slow dissipation of forces in sectors more distant from the crown area
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