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The evaluation of landslide specific risk, defined as the expected degree of loss due to landslides, requires the parameterization and the combination of a number of socio-economic and geological factors, which often needs the interaction of different skills and expertise (geologists, engineers, planners, administrators, etc.). The specific risk sub-components, i.e., hazard and vulnerability of elements at risk, can be determined with different levels of detail depending on the available auxiliary data and knowledge of the territory. These risk factors are subject to short-term variations and nowadays turn out to be easily mappable and evaluable through remotely sensed data and GIS (Geographic Information System) tools. In this work, we propose a qualitative approach at municipal scale for producing a "specific risk" map, supported by recent satellite PSI (Persistent Scatterer Interferometry) data derived from SENTINEL-1 C-band images in the spanning time 2014-2017, implemented in a GIS environment. In particular, PSI measurements are useful for the updating of a landslide inventory map of the area of interest and are exploited for the zonation map of the intensity of ground movements, needed for evaluating the vulnerability over the study area. Our procedure is presented throughout the application to the Volterra basin and the output map could be useful to support the local authorities with updated basic information required for environmental knowledge and planning at municipal level. Moreover, the proposed procedure is easily managed and repeatable in other case studies, as well as exploiting different SAR sensors in L- or X-band. [ABSTRACT FROM AUTHOR]

This work is focused on deformation activity mapping and monitoring using Sentinel-1 (S-1) data and the DInSAR (Differential Interferometric Synthetic Aperture Radar) technique. The main goal is to present a procedure to periodically update and assess the geohazard activity (volcanic activity, landslides and ground-subsidence) of a given area by exploiting the wide area coverage and the high coherence and temporal sampling (revisit time up to six days) provided by the S-1 satellites. The main products of the procedure are two updatable maps: the deformation activity map and the active deformation areas map. These maps present two different levels of information aimed at different levels of geohazard risk management, from a very simplified level of information to the classical deformation map based on SAR interferometry. The methodology has been successfully applied to La Gomera, Tenerife and Gran Canaria Islands (Canary Island archipelago). The main obtained results are discussed. [ABSTRACT FROM AUTHOR]

Multi-Temporal Satellite Interferometry (MTInSAR) is gradually evolving from being a tool developed by the scientific community exclusively for research purposes to a real operational technique that can meet the needs of different users involved in geohazard mitigation. This work aims at showing the innovative operational use of satellite radar interferometric products in Civil Protection Authority (CPA) practices for monitoring slow-moving landslides. We present the example of the successful ongoing monitoring system in the Valle D'Aosta Region (VAR-Northern Italy). This system exploits well-combined MTInSAR products and ground-based instruments for landslide management and mitigation strategies over the whole regional territory. Due to the critical intrinsic constraints of MTInSAR data, a robust regional satellite monitoring integrated into CPA practices requires the support of both in situ measurements and remotely sensed systems to guarantee the completeness and reliability of information. The monitoring network comprises three levels of analysis: Knowledge monitoring, Control monitoring, and Emergency monitoring. At the first monitoring level, MTInSAR data are used for the preliminary evaluation of the deformation scenario at a regional scale. At the second monitoring level, MTInSAR products support the prompt detection of trend variations of radar benchmarks displacements with bi-weekly temporal frequency to identify active critical situations where follow-up studies must be carried out. In the third monitoring level, MTInSAR data integrated with ground-based data are exploited to confirm active slow-moving deformations detected by on-site instruments. At this level, MTInSAR data are also used to carry out back analysis that cannot be performed by any other tool. From the example of the Valle D'Aosta Region integrated monitoring network, which is one of the few examples of this kind around Europe, it is evident that MTInSAR provides a great opportunity to improve monitoring capabilities within CPA activities. [ABSTRACT FROM AUTHOR]

Landslides recurrently impact the Italian territory, producing huge economic losses and casualties. Because of this, there is a large demand for monitoring tools to support landslide management strategies. Among the variety of remote sensing techniques, Interferometric Synthetic Aperture Radar (InSAR) has become one of the most widely applied for landslide studies. This work reviews a variety of InSAR-related applications for landslide studies in Italy. More than 250 papers were analyzed in this review. The first application dates back to 1999. The average production of InSAR-related papers for landslide studies is around 12 per year, with a peak of 37 papers in 2015. Almost 70% of the papers are written by authors in academia. InSAR is used (i) for landslide back analysis (3% of the papers); (ii) for landslide characterization (40% of the papers); (iii) as input for landslide models (7% of the papers); (iv) to update landslide inventories (15% of the papers); (v) for landslide mapping (32% of the papers), and (vi) for monitoring (3% of the papers). Sixty-eight percent of the authors validated the satellite results with ground information or other remote sensing data. Although well-known limitations exist, this bibliographic overview confirms that InSAR is a consolidated tool for many landslide-related applications. [ABSTRACT FROM AUTHOR]

This work describes a new procedure aimed to semi-automatically identify clusters of active persistent scatterers and preliminarily associate them with different potential types of deformational processes over wide areas. This procedure consists of three main modules: (i) ADAfinder, aimed at the detection of Active Deformation Areas (ADA) using Persistent Scatterer Interferometry (PSI) data; (ii) LOS2HV, focused on the decomposition of Line Of Sight (LOS) displacements from ascending and descending PSI datasets into vertical and east-west components; iii) ADAclassifier, that semi-automatically categorizes each ADA into potential deformational processes using the outputs derived from (i) and (ii), as well as ancillary external information. The proposed procedure enables infrastructures management authorities to identify, classify, monitor and categorize the most critical deformations measured by PSI techniques in order to provide the capacity for implementing prevention and mitigation actions over wide areas against geological threats. Zeri, Campiglia Marittima–Suvereto and Abbadia San Salvatore (Tuscany, central Italy) are used as case studies for illustrating the developed methodology. Three PSI datasets derived from the Sentinel-1 constellation have been used, jointly with the geological map of Italy (scale 1:50,000), the updated Italian landslide and land subsidence maps (scale 1:25,000), a 25 m grid Digital Elevation Model, and a cadastral vector map (scale 1:5000). The application to these cases of the proposed workflow demonstrates its capability to quickly process wide areas in very short times and a high compatibility with Geographical Information System (GIS) environments for data visualization and representation. The derived products are of key interest for infrastructures and land management as well as decision-making at a regional scale. [ABSTRACT FROM AUTHOR]

The potential of satellite-based interferometry for landslides activity definition is well known. Many applications have demonstrated that this technique represents a strong supporting tool for landslide risk assessment and monitoring, at both local and regional scale. The ESA' Sentinel-1 (S1) constellation acquires with high revisit-time in a conflict-free operational mode, timely distributing data without costs or restrictions. All these characteristics allow relying upon S1 service for a long-term operational and sustainable use, as a support of both disaster risk reduction and response. For this reason, more and more research projects are based on the use of S1 in geohazards monitoring and early warning. The aim of this work is to present the results achieved in the framework of the European Project (ECHO) U-Geohaz regarding landslides monitoring and early warning supporting tools based on S1. The study area of the project is the Valle d'Aosta region (VDA) that is widely affected by landslide process of different size and typology. Specifically, the Deep-Seated Gravitational Slope Deformations (DSGSDs) are the most representative in terms of area coverage. The study of the state of activity and evolution of these phenomena is very important because DSGSDs affect entire valley flanks and several villages have been built on them or nearby. The use of S1-based interferometry can potentially give a near-real time information on their activity over the whole region supporting decision makers and early warning systems. At the same time, VDA presents challenging characteristics for what concerns the radar response and thus the obtainable results. The main limiting factor is the snow coverage, which is also strongly related to the topography. The topographic relief is highly variable, ranging from 300 m a.s.l. to peaks higher than 4000 m a.s.l. with steep slopes. The regional climate is characterized by wide range of temperatures varying a lot from the mountainous zone to the bottom of the valleys, implying also a strong variation in snow precipitations. This strong variation, in space and time, affects the DInSAR results in terms of coherence and spatial coverage. In this context, a strong effort has been done to develop a processing approach to improve the spatial and temporal sampling, without losing the quality of the results. Moreover, a method that extracts the most significant Active Deformation Areas (ADA) in a semi-automatic way has been adapted and applied. The main results will be exposed. [ABSTRACT FROM AUTHOR]

A relevant change in the use of SAR interferometry for risk management and reduction has been marked by the launch of the S-1 A and S-1 B, in 2014 and 2016 respectively, which ensure a SAR acquisition every 6 days above the entire Earth and make images available few hours after the acquisition without costs and limitations. S-1 represents a reliable and low cost tool for remote monitoring at both local and national-scale, which can potentially be exploited by administrative entities and Civil Protection authorities involved in risk management activities. "U-Geohaz, Geohazard impact assessment for urban areas" is a two-year project, started the 1st of January 2018, co-funded by the European Commission, Directorate-General Humanitarian Aid and Civil Protection (ECHO). The main aim of the project is to develop a methodology based on the SAR images acquired by Sentinel-1 (S-1) constellation to assess continuously the potential impact of geohazards on urban areas and critical infrastructures. Starting from the experience and the results obtained in the previous ECHO project SAFETY (2016-2017), the aim is to make a step forward, from periodically updated maps to a near-real time geohazards mapping and monitoring. U-Geohaz will provide tools to exploit the 6-days repeatability of S1 to support early warning systems for landslide and volcanic geohazards and to evaluate the expected damage. The consortium of U-Geohaz is composed of 18 partners, from 11 European countries, including 12 Geological Surveys and 3 Civil Protection Authorities that will support the implementation of tools to be operationally useful in risk management. The use of all the developed products will be implemented in the activities of the Civil Protection Authorities involved in the project. All the implemented procedure and tools are tested and will be demonstrated on the real test scenarios of Canary Island (Gran Canaria, Tenerife and El Hierro islands, Spain) and Valle d'Aosta (Italy). The main results achieved over the two test-sites and the future steps of the project will be presented and discussed. [ABSTRACT FROM AUTHOR]