1,721,017 research outputs found
Slope stability analysis by multi-temporal DEMs and 3D modelling: The 2002 and 2007 Stromboli landslide events
No full textNatural hazard related to the volcanic activity represents a potential risk factor, particularly in the vicinity of human settlements. Besides to the risk related to the explosive and effusive activity, the instability of volcanic edifices may develop into large landslides often catastrophically destructive, as shown by the collapse of the northern flank of Mount St. Helens in 1980.
A combined approach was applied to analyse slope failures that occurred at Stromboli volcano. SdF slope stability was evaluated by using high-resolution multi-temporal DTMMs and performing limit equilibrium stability analyses.
High-resolution topographical data collected with remote sensing techniques and three-dimensional slope stability analysis play a key role in understanding instability mechanism and the related risks.
Analyses carried out on the 2002–2003 and 2007 Stromboli eruptions, starting from high-resolution data acquired through airborne remote sensing surveys, permitted the estimation of the lava volumes emplaced on the SdF slope and contributed to the investigation of the link between magma emission and slope instabilities.
Limit Equilibrium analyses were performed on the 2001 and 2007 3D models, in order to simulate the slope behavior before 2002-2003 landslide event and after the 2007 eruption. Stability analyses were conducted to understand the mechanisms that controlled the slope deformations which occurred shortly after the 2007 eruption onset, involving the upper part of slope. Limit equilibrium analyses applied to both cases yielded results which are congruent with observations and monitoring data.
The results presented in this work undoubtedly indicate that hazard assessment for the island of Stromboli should take into account the fact that a new magma intrusion could lead to further destabilisation of the slope, which may be more significant than the one recently observed because it will affect an already disarranged deposit and fractured and loosened crater area.
The two-pronged approach based on the analysis of 3D multi-temporal mapping datasets and on the application of LE methods contributed to better understanding volcano flank behaviour and to be prepared to undertake actions aimed at risk mitigation
Dynamic Monitoring of a Railway Steel Bridge with MEMS Accelerometers: First Results on the Case Study of Portella
No full textThe continuous growth of demand on railway networks requires an efficient management strategy to guarantee proper levels of safety and service. Bridges are a fundamental asset for a railway infrastructure and their integrity must be ensured implementing feasible approaches aimed at avoiding critical occurrences (e.g. collapses) by quantifying infrastructure responses to standard and critical loads, in terms of vibration features and long-term displacements. The work proposes a geomatic monitoring configuration for a new steel railway bridge -the Portella bridge- located along the Roma-Napoli railway, showing the results obtained analyzing three weeks of continuous monitoring in different seasons. The system, based on triaxial MEMS accelerometers and envisaging additional sensors (GNSS receivers) in its developments, was installed at the end of the bridge construction as a lifetime tool, and is designed to highlight the effects of the train passage. Data analysis permitted to retrieve structure accelerations and vibration normal modes (natural frequencies). The findings of the investigations will be used to improve the Finite Element model of the bridge used in the design phase
Controllo deformativi di un’ area in frana sull’Isola di Stromboli mediante integrazione di tecniche topografiche e fotogrammetriche
No full textMapping the Multi-Vulnerabilities of Outdoor Places to Enhance the Resilience of Historic Urban Districts: The Case of the Apulian Region Exposed to Slow and Rapid-Onset Disasters
Full text linkRecent critical events brought attention to the increasing exposure of urban environments to both slow and rapid onset disasters, which arise from both anthropogenic and natural causes. These events have particularly severe effects on historic centres, which are characterized by high levels of vulnerability and valuable assets exposed to risk. To minimize the impact on tangible and intangible cultural heritage values, especially in outdoor public areas such as squares and streets, it is crucial to establish coherent mitigative and adaptive solutions for different types of hazards. This research presents a methodology aimed at defining levels of multi-vulnerabilities in historic districts in the Apulia Region (Italy), considering the recurrent hazards to which the latter is prone. It uses a multi-step process based on structured and non-structured methodologies and tools for single risks, examined in combination, to determine the main properties characterizing the vulnerability assessment. The dataset was analyzed in a GIS environment to evaluate the selected Apulian case study (Molfetta) in Multi-Asynchronous Hazard scenarios, showing the compounded levels of criticalities for open areas and streets. This information is intended to support authority and emergency managers in identifying priority interventions and increasing the resilience of the outdoor public places
Landslide risk and monitoring system for conservation of Vardzia monastery, Georgia
No full textThe present paper reports preliminary results of a feasibility project developed in cooperation with National Agency for Cultural Heritage Preservation of Georgia, aimed at envisaging the stability conditions of the slope-forming rocks of the Vardzia Monastery (rupestrian city cave in the south-western Georgia) and finalized to the implementation of a low impact monitoring systems together with long term mitigation/conservation policies. A field analysis was conducted to reconstruct geometry of the rock cliff, characteristics of discontinuities, main failure modes of potential unstable blocks, magnitude of phenomena and geom.-echanical parameters. Instability processes are the result of different combination of causative factors such as: lithology, frequency and orientation of discontinuities versus slope orientation, physical and mechanical characteristics of slope-forming materials, morphological and hydrological dynamics. The adoption of different survey techniques (e.g. 3D laser scanner, Ground Base Radar Interferometry) adopted together could be the best solution in the interdisciplinary field of Cultural Heritage preservation policies. © 2013 Taylor & Francis Group, London
Automated geomatic system for monitoring historical buildings during tunneling in Roma, Italy
No full textThe present work is focused on the preliminary results obtained through the geomatic integrated monitoring system currently running at the test site of the Basilica of Maxentius in the Roman Forum. The system is aimed at controlling a number of archaeological sites which can be potentially affected by the tunneling works for a new metro line which is presently under construction. It includes different high precision geomatic sensors controlled by a centralized control station which continuously acquire data at high frequency. In order to identify a reliable processing procedure and assess the quality of the collected data, we started to develop and experiment a preliminary analysis of the data collected in the first period of the system operation (before the start of the excavation works). This activity allowed us to assess the performance of each sensor, focusing on the capability of the system to control also the stability of the monitoring stations. The obtained results will be adopted to better define an automated procedure for future massive data processing
Softening and swelling mechanism affecting south slope of Civita di Bagnoregio (VT)
No full textCivita di Bagnoregio is a small village in Central Italy, located on the top of a hill and affected by landslides that are progressively reducing the urban area. The access consists of a pedestrian bridge that connects Bagnoregio municipality to the village. The south slope beneath the bridge, is involved by frequent instability phenomena. This work describes the analysis carried out and it aimed at the definitions of geological and geotechnical mechanism affecting the above mentioned slope. A geotechnical survey has been carried out. These surveys showed the presence of a superficial layer, resulting from the softening and swelling of underlying clay-silty strongly overconsolidated, responsible for the superficial landslide phenomena. A slope stability and a 3D laser scanner model has been carried out. The analysis demonstrates that a correct design for the landscape preservation and consolidation of unstable towns needs an understanding of triggering mechanism and geotechnical properties of the involved soils. © 2013 Taylor & Francis Group, London
La fotogrammetria digitale applicata in aree vulcaniche : l’area sommitale del monte Etna
No full textIntegration of multi-sensor MTInSAR and ground-based geomatic data for the analysis of non-linear displacements affecting the urban area of Chieuti, Italy
Full text linkSlow instability phenomena can turn into rapid events, showing sudden accelerations and potentially developing in a threat for structures and people. In such scenarios, an in-depth understanding of the spatial and temporal evolution of the ground surface displacement field becomes essential for preventing potential catastrophes. In this work, Multi-Temporal Interferometry SAR (MTInSAR) technique based on COSMO-SkyMed and Sentinel-1 SAR acquisitions and ground measurements have been used to study an ongoing instability occurrence, affecting the urban area of Chieuti, a town located in the Southern Italy. Archives of C and X-band SAR data and geomatic monitoring observations spanning seven, five and one year, respectively, have been analyzed exploiting the complementary characteristics of these datasets. This enabled the accurate spatial-temporal characterization of the ground displacement field in the study area, the identification of sectors evidencing instability problems and a comprehensive reliability assessment of the detected displacements trends, characterized by strong non-linearities. Moreover, the multi-geometry DInSAR analysis allowed to evaluate the horizontal and vertical components of the detected motion, confirming the nature of the instability process, related to a deep landslide mechanism affecting the western slope of the town
La fotogrammetria digitale applicata in aree vulcaniche: l’area sommitale del monte Etna
No full textLe aree vulcaniche sono frequentemente soggette a variazioni topografiche dovute a colate di lava od eventi di frana collegati all'attività eruttiva. La disponibilità di cartografia aggiornata e dettagliata contribuisce a realizzare analisi di tipo quantitativo che contribuiscono alla conoscenza ed al monitoraggio dei fenomeni effusivi. La topografia è un importante parametro di input per i codici di simulazione che vengono adottati per costruire mappe di hazard e valutare l'evoluzione temporale dei flussi lavici. In questo lavoro viene presentato l'aggiornamento della topografia della parte sommitale dell'Etna estratta da un volo fotogrammetrico realizzato nell'agosto 2004. Quest'area è stata infatti interessata da diverse eruzioni effusive tra il 1998, anno di aggiornamento della Carta Tecnica Provinciale di Catania (CTP-1998), e il 2004. Vengono inoltre presentate alcune prove di editing del DTM 2004 per eliminare la vegetazione. La procedura di estrazione automatica del DTM può infatti portare, in aree ricoperte da fitta vegetazione, ad una rappresentazione errata delle caratteristiche morfologiche della superficie. Questo lavoro presenta, infine, il calcolo del volume di un flusso lavico emesso nel 2002 sul versante NE. Questo è stato ottenuto dal confronto tra il DTM 2004 e il DTM estratto dalla CTP-1998 dopo aver valutato l'ondulazione del geoide nella zona in esame. I due DTM si riferiscono, infatti, a due diversi sistemi di riferimento altimetrici: il 2004 si basa sulle quote ellissoidiche mentre il 1998 utilizza quote geoidich
- …
