The Island of Ischia is located in the Tyrrhenian Sea, approximately 30 km WSW from the city of N... more The Island of Ischia is located in the Tyrrhenian Sea, approximately 30 km WSW from the city of Naples in Southern Italy. The Island is a debris-flow prone area due to its steep slopes covered by loose volcanic lithologies. On April 30th 2006, following several hours of rainfall, four soil slips were triggered on the slopes of Mt. Vezzi (about 400 m a.s.l.) in the SE portion of the island. The soil slips changed quickly into debris flows that reached the inhabited at the foot of the hill, causing four victims, destroying several buildings and forcing the evacuation of 250 inhabitants. This work presents the analysis of the triggering and propagation phase of the phenomena. In particular, to model the triggering conditions, a finite element analysis was used to reconstruct the variations in pore water pressure during the event in transient conditions. The limit equilibrium slope-stability method was then applied using the temporal pore water pressure distributions derived from the seepage analysis. The dynamic modeling of the propagation phase was carried out by means of two dynamic codes DAN-W and FLO2D, with the aim of evaluating the residual hazard linked to other potential debris flows recognized in the same area. Once the DAN-W and FLO2D models satisfactorily reproduced the 30th April events, the simulations were extended to a larger area, whose susceptibility to future landslide events has been determined through a detailed geomorphological survey and a following GIS analysis.
The High City of Antananarivo is one of the most important cultural heritage sites of Madagascar,... more The High City of Antananarivo is one of the most important cultural heritage sites of Madagascar, on the UNESCO Tentative List since 2016. Built on the hilltop of the Analamanga Hill, a granite ridge overlooking the Ikopa River valley, it is renowned for its baroque-style palaces, such as the Rova royal complex, and neo-Gothic cathedrals dating back to the nineteenth century. During the winter of 2015, the twin cyclones Bansi and Chedza hit the urban area of Antananarivo, triggering floods and shallow landslides, as well as causing thousands of evacuees and many casualties. Between 2018 and 2019 several rockfalls occurred from the rock cliffs of the Analamanga hills, destroying housings and killing over 30 people. Both events showed that landslides can pose a high risk to the safety of the inhabitants, the infrastructure, and the cultural heritage of the High City. To assess the landslide hazard in the Analamanga Hill area, an integrated approach was adopted by means of the followin...
Several countries worldwide are funding large-scale programs to mitigate landslide risk by implem... more Several countries worldwide are funding large-scale programs to mitigate landslide risk by implementing engineering remedial works. However, the overall effectiveness of such measures is rarely monitored, and they are typically performed at the slope scale without fully exploiting the wide-area capabilities of remote sensing technologies. A multi-scale and multi-source monitoring procedure for evaluating the slope stability and the effectiveness of related remedial works was proposed in this study and applied in the middle section of the Three Gorges Reservoir Area (TGRA), China. The area is highly exposed to landslide hazards, and a massive program of engineering remedial works was recently implemented. Satellite interferometric synthetic aperture radar (InSAR)-based techniques were first exploited at the regional scale with the objective to provide a general overview of the deformative scenario and to highlight localized problems (active landslides or high deformation zones) to be...
Natural Hazards and Earth System Sciences Discussions, 2017
A big challenge in terms or landslide risk mitigation is represented by the increasing of the res... more A big challenge in terms or landslide risk mitigation is represented by the increasing of the resiliency of society exposed to the risk. Among the possible strategies to reach this goal, there is the implementation of early warning systems. This paper describes a procedure to improve early warning activities in areas affected by high landslide risk, such as those classified as Critical Infrastructures for their central role in society. <br><br> This research is part of the project <q>LEWIS (Landslides Early Warning Integrated System): An Integrated System for Landslide Monitoring, Early Warning and Risk Mitigation along Lifelines</q>. <br><br> LEWIS is composed of a susceptibility assessment methodology providing information for single points and areal monitoring systems, a data transmission network and a Data Collecting And Processing Center (DCPC), where readings from all monitoring systems and mathematical models converge and which sets the bas...
The Island of Ischia is located in the Tyrrhenian Sea, approximately 30 km WSW from the city of N... more The Island of Ischia is located in the Tyrrhenian Sea, approximately 30 km WSW from the city of Naples in Southern Italy. The Island is a debris-flow prone area due to its steep slopes covered by loose volcanic lithologies. On April 30th 2006, following several hours of rainfall, four soil slips were triggered on the slopes of Mt. Vezzi (about 400 m a.s.l.) in the SE portion of the island. The soil slips changed quickly into debris flows that reached the inhabited at the foot of the hill, causing four victims, destroying several buildings and forcing the evacuation of 250 inhabitants. This work presents the analysis of the triggering and propagation phase of the phenomena. In particular, to model the triggering conditions, a finite element analysis was used to reconstruct the variations in pore water pressure during the event in transient conditions. The limit equilibrium slope-stability method was then applied using the temporal pore water pressure distributions derived from the seepage analysis. The dynamic modeling of the propagation phase was carried out by means of two dynamic codes DAN-W and FLO2D, with the aim of evaluating the residual hazard linked to other potential debris flows recognized in the same area. Once the DAN-W and FLO2D models satisfactorily reproduced the 30th April events, the simulations were extended to a larger area, whose susceptibility to future landslide events has been determined through a detailed geomorphological survey and a following GIS analysis.
The High City of Antananarivo is one of the most important cultural heritage sites of Madagascar,... more The High City of Antananarivo is one of the most important cultural heritage sites of Madagascar, on the UNESCO Tentative List since 2016. Built on the hilltop of the Analamanga Hill, a granite ridge overlooking the Ikopa River valley, it is renowned for its baroque-style palaces, such as the Rova royal complex, and neo-Gothic cathedrals dating back to the nineteenth century. During the winter of 2015, the twin cyclones Bansi and Chedza hit the urban area of Antananarivo, triggering floods and shallow landslides, as well as causing thousands of evacuees and many casualties. Between 2018 and 2019 several rockfalls occurred from the rock cliffs of the Analamanga hills, destroying housings and killing over 30 people. Both events showed that landslides can pose a high risk to the safety of the inhabitants, the infrastructure, and the cultural heritage of the High City. To assess the landslide hazard in the Analamanga Hill area, an integrated approach was adopted by means of the followin...
Several countries worldwide are funding large-scale programs to mitigate landslide risk by implem... more Several countries worldwide are funding large-scale programs to mitigate landslide risk by implementing engineering remedial works. However, the overall effectiveness of such measures is rarely monitored, and they are typically performed at the slope scale without fully exploiting the wide-area capabilities of remote sensing technologies. A multi-scale and multi-source monitoring procedure for evaluating the slope stability and the effectiveness of related remedial works was proposed in this study and applied in the middle section of the Three Gorges Reservoir Area (TGRA), China. The area is highly exposed to landslide hazards, and a massive program of engineering remedial works was recently implemented. Satellite interferometric synthetic aperture radar (InSAR)-based techniques were first exploited at the regional scale with the objective to provide a general overview of the deformative scenario and to highlight localized problems (active landslides or high deformation zones) to be...
Natural Hazards and Earth System Sciences Discussions, 2017
A big challenge in terms or landslide risk mitigation is represented by the increasing of the res... more A big challenge in terms or landslide risk mitigation is represented by the increasing of the resiliency of society exposed to the risk. Among the possible strategies to reach this goal, there is the implementation of early warning systems. This paper describes a procedure to improve early warning activities in areas affected by high landslide risk, such as those classified as Critical Infrastructures for their central role in society. <br><br> This research is part of the project <q>LEWIS (Landslides Early Warning Integrated System): An Integrated System for Landslide Monitoring, Early Warning and Risk Mitigation along Lifelines</q>. <br><br> LEWIS is composed of a susceptibility assessment methodology providing information for single points and areal monitoring systems, a data transmission network and a Data Collecting And Processing Center (DCPC), where readings from all monitoring systems and mathematical models converge and which sets the bas...
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