1,720,998 research outputs found
High resolution 3D geomechanical characterization for the evaluation of rockslide susceptibility scenarios
No full textAllo scopo di valutare gli scenari di rischio connessi a scivolamenti di roccia, si propone una metodologia integrata basata su rilievi in situ geologici e geomeccanici di dettaglio, e sull’utilizzo di tecnologie di remote sensing basate a terra quali il rilievo laser scanning (Terrestrial laser scanning=TLS) e la termografia ad infrarossi (Terrestrial Infrared Thermography=TIR). L’obiettivo della metodologia proposta è di ottenere una accurata caratterizzazione del versante roccioso investigato con le seguenti finalità: i) svolgere una dettagliata caratterizzazione geomeccanica 3D dell’ammasso roccioso; ii) individuare le porzioni di ammasso roccioso più critiche in termini di fenomeni di instabilità di versante; iii) calcolarne i volumi; iv) svolgere una dettagliata analisi di stabilità. In particolare è stato utilizzato un tool di Matlab (DiAna= Discontinuity Analysis) allo scopo di estrarre dati geomeccanici tridimensionali di dettaglio dalla nuvola di punti ad alta risoluzione ottenuta dal rilievo TLS. È stato inoltre eseguito un rilievo termografico per la valutazione qualitativa della filtrazione in corrispondenza delle discontinuità delimitanti le porzioni di ammasso roccioso più critici. L’integrazione fra le tecniche di remote sensing utilizzate ed i rilievi tradizionali in situ svolti, ha consentito di investigare settori di versante roccioso altrimenti non accessibili, restituendo una dettagliata caratterizzazione tridimensionale geometrica e geomeccanica dell’ammasso roccioso investigato, fornendo inoltre accurati parametri di input per l’analisi di stabilità
Clean and renewable energy from the Arno River: A feasibility study in the Province of Florence (northern Italy)
No full textDuring a joint project between the Provincia di Firenze Administration and the Earth Sciences Department of the University of Firenze, the Arno riverbed was studied from the terminal portion of the Upper Valdano up to the Middle Valdarno (about 75 km). In particular, we analysed the preservation status of the existing weirs, which are nowadays the most important hydraulic works as concern the profile riverbed conservation and the fluvial dynamics. Such research was oriented to perform a practical analysis useful for a complete recovery of the hydraulic functionality and also for a possible renovation of some structures in order to produce clean electricity, following the current sensitivity in many national and international institutions. This analysis resulted in the determination of a different degree of feasibility, identifying from a technical point of view the most suitable weir and its annex for a quick recovery intervention and highlighting their economic impact on potential investors that might be attracted to the economic income related to the sale of electricity to the local network
Back monitoring of the San Leo (northern Italy) rock cliff by means of SqueeSAR technique
No full textSan Leo (Emilia-Romagna Region, northern Italy) is a medieval town built on top of an isolated rock massif, located within the Marecchia river valley. The area is historically affected by rock fall events occurred during the last 400 years. As a consequence of a huge rock fall, occurred on February 27th 2014, minor structural damages were reported and a few buildings of the town were promptly evacuated as a precautionary measure. Today the San Leo cultural heritage is in safety but it is still threatened by the instability of the cliff newly formed by the rock fall. In this framework, satellite remote sensing tools (Synthetic Aperture Radar) were used in order to evaluate the presence of precursory phenomena with respect to the 2014 rock fall. For this purpose 74 COSMO-SkyMed archival images were processed by using the SqueeSAR approach. Results highlighted the presence of: i) ground deformations which still affect the past landslide deposits surrounding the rock massif: ii) displacements which can be considered as possible precursory phenomena
Application of infrared thermography for landslide mapping: The rotolon DSGDS case study
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Debris flow hazard assessment by means of numerical simulations: implications for the Rotolon creek valley (Northern Italy)
No full textOn 4th November 2010, a debris flow detached from a large debris cover accumulated above the lowermost portion of the Rotolon landslide (Vicentine Pre-Alps, NE Italy) and channelized in the valley below within the Rotolon Creek riverbed. Such event evolved into a highly mobile and sudden debris flow, damaging some hydraulic works and putting at high risk four villages located along the creek banks. A monitoring campaign was carried out by means of a ground based radar interferometer (GB-InSAR) to evaluate any residual displacement risk in the affected area and in the undisturbed neighbouring materials. Moreover, starting from the current slope condition, a landslide runout numerical modelling was performed by means of DAN-3D code to assess the impacted areas, flow velocity, and deposit distribution of the simulated events. The rheological parameters necessary for an accurate modelling were obtained through the back analysis of the 2010 debris flow event. Back analysis was calibrated with all of the available terrain data coming from field surveys and ancillary documents, such as topographic, geomorphological and geological maps, with pre- and post-event LiDAR derived DTMs, and with orthophotos. Finally, to identify new possible future debris flow source areas as input data for the new modelling, all the obtained terrain data were reanalysed and integrated with the GB-InSAR displacement maps; consequently, new simulations were made to forecast future events. The results show that the integration of the selected modelling technique with ancillary data and radar displacement maps can be a very useful tool for managing problems related to debris flow events in the examined area
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
Emergency management of the 2010 Mt. Rotolon landslide by means of a local scale GB-InSAR monitoring system
Full text linkAbstract. Diffuse and severe slope instabilities affected the whole Veneto region (Northeast Italy) between October 31st and November 2nd 2010, following a period of heavy and persistent rainfall. In this context on November 4th 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 putting at high risk bridges, local roads, together with population of the Maltaure, Turcati and Parlati villages located along the creek banks and of the Recoaro Terme town. 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 scientific institutions. On December 8th 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 manage the emergency phase. This paper describes the outcomes of a two years GB-InSAR monitoring campaign (December 2010–December 2012), 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 decision making process in a critical landslide scenario.
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Analysis of building deformation in landslide area using multisensor PSInSAR™ technique
Full text linkAbstractBuildings are sensitive to movements caused by ground deformation. The mapping both of spatial and temporal distribution, and of the degree of building damages represents a useful tool in order to understand the landslide evolution, magnitude and stress distribution. The high spatial resolution of space-borne SAR interferometry can be used to monitor displacements related to building deformations. In particular, PSInSAR technique is used to map and monitor ground deformation with millimeter accuracy. The usefulness of the above mentioned methods was evaluated in San Fratello municipality (Sicily, Italy), which was historically affected by landslides: the most recent one occurred on 14th February 2010. PSInSAR data collected by ERS 1/2, ENVISAT, RADARSAT-1 were used to study the building deformation velocities before the 2010 landslide. The X-band sensors COSMO-SkyMed and TerraSAR-X were used in order to monitor the building deformation after this event. During 2013, after accurate field inspection on buildings and structures, damage assessment map of San Fratello were created and then compared to the building deformation velocity maps. The most interesting results were obtained by the comparison between the building deformation velocity map obtained through COSMO-SkyMed and the damage assessment map. This approach can be profitably used by local and Civil Protection Authorities to manage the post-event phase and evaluate the residual risks
Rapid assessment of geo-hydrological hazards in Antananarivo (Madagascar) historical centre for damage prevention
Full text linkThe historical centre of Antananarivo represents one of the most
important cultural heritage sites in Madagascar. During 2015, the
whole city area was severely affected by geo-hydrological hazards
due to cyclonic rain, resulting in severe flooding, and in widespread
shallow landslides along the hillslopes. This event proved
the vulnerability to geo-hydrological risk of the Upper town’s historical
buildings. In October 2017, a geo-hydrological hazard mapping
was performed in the Upper Town by combining field
surveys, remote sensing and geomatic data analysis in a GIS
environment. This provided detailed products such as a geological-
geomorphological map, a map of the hydrographic network
and of the creek basins, and a geodatabase to be used for
detecting areas prone to erosion and geo-hydrological hazards.
The final aim was to understand the geological, geomorphological
and hydrographic features of the Upper Town, in order locate the
more critical areas and to recommend priority works to be carried
out, as a first step toward a risk management strategy and a conservation/
valorization plan for building the resilience of the site.
The results highlighted that a Cultural Heritage site protection
strategy can be planned also in case of limited data, which is a
frequent condition in developing countries
Synergic use of satellite and ground based remote sensing methods for monitoring the San Leo rock cliff (Northern Italy)
Full text linkAbstractThe historic town of San Leo (Emilia Romagna Region, northern Italy) is located on top of an isolated rock massif above the Marecchia River valley hillside. On February 27th 2014, a northeastern sector of the massif collapsed; minor structural damages were reported in the town and a few buildings were evacuated as a precautionary measure. Although no fatalities occurred and the San Leo cultural heritage suffered no damage, minor rock fall events kept taking place on the newly formed rock wall, worsening this hazardous situation. In this framework, a monitoring system based on remote sensing techniques, such as radar interferometry (both spaceborne and ground-based) and terrestrial laser scanning, was planned in order to monitor the ground deformation of the investigated area and to evaluate the residual risk. In this paper the main outlines of a 1-year monitoring activity are described, including a pre-event analysis of possible landslide precursors and a post-event analysis of the displacements of both the collapse-affected rock wall sector and the rock fall deposits
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