Spatio-temporal analysis of SAR based time series for slope instability characterization : the Corvara in Badia landslide ( Dolomites , Italy )

The aim of this study is to estimate the influence of different forcing factors acting on instability phases of a slow alpine earthslide-earthflow, by means of the characteristics of decomposed deformations signals derived by displacement rates measured in its different sectors. In this work we analyze a slow landslide located ESE from Corvara in Badia, a famous tourist area in the Dolomites (NE Italy). Road, infrastructure, ski and other recreational facilities, isolated buildings close to the town of Corvara and finally an artificial reservoir for snow production are threatened and occasionally damaged by this mass movement. It flows from 2000m s.l. to 1500m s.l. where a paleo-landslide deposit is partially covered and re-activated. In the last 10 years the Province of Bolzano carried out discontinuous GPS surveys between 5 and 1 times per year to define the landslide’s level of hazard. The landslide volume is resulted to be 30Mm3, xtending downslope for approx. 3km, with displacement rates between few centimeters and slightly less than 10m per year. To analyze this area we used data from active radar sensors (SAR – Synthetic perture Radar). The SAR-based dataset consists in high resolution X-band SAR data from the Cosmo SkyMed (CSK) mission acquired every 8 days from August 2010 to September 2011. Part of the 38 CSK scenes contain the back-scattering signal from 17 artificial reflectors (AR) installed along the AOI and partially on existing GPS benchmarks for data validation and integration. The ARs back scattering signal has been elaborated in order to track their displacement from August 2010 to September 2011, in the lower zone of the landslide, as well as from March 2011 to September 2011 in the higher part, excluding the period when the snow was covering the surface. The signals have been analyzed with Fourier and wavelet methods to identify the different frequencies and nature of the components. T and Mann-Kendall tests have been used to assess the presence of trends. Fits with exponential functions of the de-trended and de-seasonalized signal have been performed to identify the presence of dissipating deformations. We observed that the signal of velocity and acceleration is characterized by the coexistence of different factors: first, periodic signals associated to seasonal and gravitational kinematic behavior; second, decay effects due to instability events. Moreover, using different points is possible to observe the signal propagation both in time and space. This analysis allow us to determine the spatio-temporal scale of different forcing events and their effect on the total landslide area. Finally, this study represent a new approach for identify the spatio-temporal nature of different factors in the evolution of the landslide for setting-up a system of conscious prediction of aintenance tasks of he exposed structures. The use of the SAR data demonstrated to be an innovative tool for high temporal resolution surveys with a big amount of points that in comparison with GPS surveys results to be conomically convenient in wide AOI

Seismic damage scenarios for Mayotte: a tool for disaster management

A new marine volcano is erupting offshore Mayotte since May 2018, generating numerous earthquakes. The population felt many of them and the stronger shaking of the ongoing sequence caused slight damage to buildings. Historical records also confirm that damaging earthquakes had occurred in the past in this region. Seismic damage scenarios are a key tool for supporting the decision-making process, the preparedness, and for designing appropriate emergency responses. This paper provides the outcomes of a work consisting in improving the seismic risk assessment as a part of disaster risk governance and exposes the scientific background of this workflow. It illustrates its use with two earthquakes. Related post-seismic surveys provide observations that are useful to check the validity of the reference dataset. The paper also discusses the main characteristics of the rapid loss assessment tool that has been developed to provide operational information for crisis management

Retrieving high resolution deformation patterns of slow moving landslides by COSMO-SkyMed SAR data: a sustainable long term monitoring system using artificial reflectors

Retrieving high resolution deformation patterns of slow moving landslides by COSMO-SkyMed SAR data: a sustainable long term monitoring system using artificial reflector

A new approach to structured processing of feedback for discovering and investigating interconnections, cascading events and disaster chains

International audiencePost-disaster information processing is relevant for the continuous improvement of operations and the reduction of risks. The current methodologies for post-disaster review suffer from several limitations, which reduce their use as a way of translating narrative in data for qualitative and quantitative analysis. Learning or effective knowledge sharing need a common formalism and method. Ontologies are the reference tool for structuring information in a "coded" data structure. Using the investigation of disaster management during the 2017 hurricane season in the French West Indies within the scope of the ANR "APRIL" project, this contribution introduces a methodology and a tool for providing a graphical representation of experiences for post-disaster review and lessons learning, based on a novel approach to case-based ontology development

A new approach for slope instability characterization: spatio-temporal analysis of SAR based time series applied to the corvara in Badia landslide test-case (Dolomites, Italy)

The aim of this study is to discern and estimate the influence of different forcing factors acting on instability phases of a slow alpine earthslide-earthflow. To reach this scope, the deformation signals of displacement rates measured by Persistent Scatterers Interferometry (PSI) have been decomposed and analyzed taking in mind the dynamics of the different sectors included in the mass movement already known by previous studies

Un retour d’expérience graphique sur la crise cyclonique de 2017 aux Antilles

International audienceRéaliser le retour d’expérience d’une crise extrême, telle la crise cyclonique de 2017 aux Antilles fran- çaises, est une procédure délicate et complexe. Elle nécessite non seulement d’intégrer les contraintes et incertitudes liées au passage de trois cyclones majeurs, mais également les effets des actions et décisions prises par l’important réseau des acteurs mobilisés à tous les niveaux d’intervention. La capitalisation d’expériences individuelles et collectives au sein d’un RETEX unique est donc primordiale pour optimiser la prise de décision en conduite de crise « hors-norme », notamment dans un contexte de changement climatique aux effets imprédictibles. Dans cet article, nous proposons un retour d’expérience sous la forme d’une base de données graphique qui intègre des informations hétérogènes et descriptives des aléas, des actions menées, des interactions entre les services, etc. Il s’agit, in fine, d’enrichir les connaissances et d’appuyer les décisions, à tous les niveaux (opérationnel, tactique et stratégique), tant dans le public que dans le privé

Un retour d'expérience graphique sur la crise cyclonique de 2017 aux Antilles

National audienceRéaliser le retour d’expérience d’une crise extrême, telle la crise cyclonique de 2017 aux Antilles françaises, est une procédure délicate et complexe. Elle nécessite non seulement d’intégrer les contraintes et incertitudes liées au passage de trois cyclones majeurs, mais également les effets des actions et décisions prises par l’important réseau des acteurs mobilisés à tous les niveaux d’intervention. La capitalisation d’expériences individuelles et collectives au sein d’un RETEX unique est donc primordiale pour optimiser la prise de décision en conduite de crise « hors-norme », notamment dans un contexte de changement climatique aux effets imprédictibles. Dans cet article, nous proposons un retour d’expérience sous la forme d’une base de données graphique qui intègre des informations hétérogènes et descriptives des aléas, des actions menées, des interactions entre les services, etc. Il s’agit, in fine, d’enrichir les connaissances et d’appuyer les décisions, à tous les niveaux (opérationnel, tactique et stratégique), tant dans le public que dans le privé