Francesco Zucca

Geological Interpretation of PSInSAR Data at Regional Scale.

Results of a PSInSAR™ project carried out by the Regional Agency for Environmental Protection (ARPA) in Piemonte Region (Northern Italy) are presented and discussed. A methodology is proposed for the interpretation of the PSInSAR™ data at the regional scale, easy to use by the public administrations and by civil protection authorities. Potential and limitations of the PSInSAR™ technique for ground movement detection on a regional scale and monitoring are then estimated in relationship with different geological processes and various geological environments.

A methodology for improving landslide PSI data analysis

In this work, we present a methodology for improving persistent scatterer interferometry (PSI) data analysis for landslide studies. This methodology is a revision of previously described procedures with several improved and newly proposed aspects. To both evaluate and validate the results from this methodology, we used various persistent scatterer (PS) datasets from different satellites (ERS – ENVISAT, Radarsat, TerraSAR-X, and ALOS PALSAR) that were processed using three PSI techniques (stable point network – SPN, permanent scatterer interferometry – PSInSAR™, and SqueeSAR™) to map and monitor landslides in various mountainous environments in Spain and Italy. This methodology consists of a preprocessing model that predicts the presence of a PS over a certain area and a post-processing method used to determine the stability threshold, project the line of sight (LOS) velocity along the slope, estimate the E–W and vertical components of the velocity, and identify anomalous areas.

A User-Oriented Methodology for DInSAR Time Series Analysis and Interpretation: Landslides and Subsidence Case Studies

Recent advances in multi-temporal Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) have greatly improved our capability to monitor geological processes. Ground motion studies using DInSAR require both the availability of good quality input data and rigorous approaches to exploit the retrieved Time Series (TS) at their full potential. In this work we present a methodology for DInSAR TS analysis, with particular focus on landslides and subsidence phenomena. The proposed methodology consists of three main steps: (1) pre-processing, i.e., assessment of a SAR Dataset Quality Index (SDQI) (2) post-processing, i.e., application of empirical/stochastic methods to improve the TS quality, and (3) trend analysis, i.e., comparative implementation of methodologies for automatic TS analysis. Tests were carried out on TS datasets retrieved from processing of SAR imagery acquired by different radar sensors (i.e., ERS-1/2 SAR, RADARSAT-1, ENVISAT ASAR, ALOS PALSAR, TerraSAR-X, COSMO-SkyMed) using advanced DInSAR techniques (i.e., SqueeSAR™, PSInSAR™, SPN and SBAS). The obtained values of SDQI are discussed against the technical parameters of each data stack (e.g., radar band, number of SAR scenes, temporal coverage, revisiting time), the retrieved coverage of the DInSAR results, and the constraints related to the characterization of the investigated geological processes. Empirical and stochastic approaches were used to demonstrate how the quality of the TS can be improved after the SAR processing, and examples are discussed to mitigate phase unwrapping errors, and remove regional trends, noise and anomalies. Performance assessment of recently developed methods of trend analysis (i.e., PS-Time, Deviation Index and velocity TS) was conducted on two selected study areas in Northern Italy affected by land subsidence and landslides. Results show that the automatic detection of motion trends enhances the interpretation of DInSAR data, since it provides an objective picture of the deformation behaviour recorded through TS and therefore contributes to the understanding of the on-going geological processes.

Land subsidence, Ground Fissures and Buried Faults: InSAR Monitoring of Ciudad Guzmán (Jalisco, Mexico)

We study land subsidence processes and the associated ground fissuring, affecting an active graben filled by thick unconsolidated deposits by means of InSAR techniques and fieldwork. On 21 September 2012, Ciudad Guzman (Jalisco, Mexico) was struck by ground fissures of about 1.5 km of length, causing the deformation of the roads and the propagation of fissures in adjacent buildings. The field survey showed that fissures alignment is coincident with the escarpments produced on 19 September 1985, when a strong earthquake with magnitude 8.1 struck central Mexico. In order to detect and map the spatio-temporal features of the processes that led to the 2012 ground fissures, we applied InSAR multi-temporal techniques to process ENVISAT-ASAR and RADARSAT-2 satellite SAR images acquired between 2003 and 2012. We detect up to 20 mm/year of subsidence of the northwestern part of Ciudad Guzman. These incremental movements are consistent with the ground fissures observed in 2012. Based on interferometric results, field data and 2D numerical model, we suggest that ground deformations and fissuring are due to the presence of areal subsidence correlated with variable sediment thickness and differential compaction, partly driven by the exploitation of the aquifers and controlled by the distribution and position of buried faults.

The Use of PSInSAR™ and SqueeSAR™ Techniques for Updating Landslide Inventories

Measurements of ground deformation with millimetric accuracy and the reconstruction of the history of deformations in the last 20 years with Persistent Scatterer techniques have a high potential for landslides studies. In this work we analyze pro and cons of PSI techniques to update the Italian Inventory of Landslides (IFFI) using data from ERS 1/2 (1992–2001) and RADARSAT (2003–2010) satellites. The study area is located in North-Western Italy and belongs to three regions: Piemonte, Lombardia and Liguria.

Composition of modern stream sands derived from sedimentary source rocks in a temperate climate (Northern Apennines, Italy)

Abstract The Northern Apennine is a moderate relief thrust–fold belt (maximum elevation of less than 2000 m above sea level) lying in an area of temperate climate, drained by short (mean 50 km) transversal streams flowing northwards into the Po River main channel. The mountain range is mostly made-up of sedimentary rocks with minor ophiolite slices. The source rock types of nine contiguous watersheds, draining an overall area of more than 2800 km 2 , were quantitatively defined through a Geographical Information System (GIS). The bedrock lithology at the source area was compared with the composition of the medium-sized fluvial sand to evaluate how the various types of sedimentary source rocks are represented in the stream sand population. The sand provenance approach has two approximation levels; the first level distinguishes the source rock types and constrains some assumptions about the degree of recycling; the second level calculates the contribution of different source rock types according to the previous results. Provenance modelling obtained through this method fits well with the real geology of the eroded landscape. This provides an actualistic example that can be useful for a quantitative provenance approach to the study of ancient sediments fed by recycled sedimentary thrust–fold belts.

Rainfall-Triggered Shallow Landslides Mapping Through Pleiades Images

This paper presents the analysis of Pleiades images for the detection and the mapping of rainfall-induced shallow landslides in an area located in the Northern Apennines of Italy. The high resolution of the used images allowed to efficiently recognize also the landslides with small size and to quickly create an inventory map of these phenomena. Field investigations carried up for checking the real presence of the mapped landslides showed a good agreement with the detected through Pleiades images landslides, also in terms of appearance and size of these phenomena. For these reasons Pleiades images can be an useful device for identifying landslides events and to create a complete database of susceptible areas.

Land cover changes in an abandoned agricultural land in the Northern Apennine (Italy) between 1954 and 2008: Spatio-temporal dynamics

We report the spatio-temporal dynamics of land cover changes from 1954 to 2008 in a hilly mountainous area in the Italian northern Apennine, and ecological factors and processes associated with these dynamics. Land cover patches were mapped and analysed at three time periods (1954, 1980 and 2008). Changes over time were detected by analysing a combination of multitemporal source data from airborne images and from field surveys. Relationships between cover classes and environmental variables were analysed for the year 2008. Grasslands and scrublands (corresponding to the Natura 2000 Habitats 6210 and 5130, respectively) were found to be the most threatened communities; they occupy small portions of the studied area and are subject to a marked dynamic towards the higher stages of the vegetation successions including a mesophilous and a thermophilous succession. The ability to estimate persistence times and evolution trends of vegetation types following land abandonment is an important tool in land management. Our combined approach yielded a good picture of the vegetation involved in biodiversity loss consequent to land abandonment, as well as estimation of the expected time for this loss to occur.

Ten-years sediment dynamics in Northern Adriatic sea investigated through optical remote sensing observations

Understanding the factors influencing sediment fluxes is a key issue to interpret the evolution of coastal sedimentation under natural and human impact and relevant for the natural resources management. Despite river plumes represent one of the major gain in sedimentary budget of littoral cells, complex behavior of coastal plumes, like river discharge characteristics, wind stress and hydro-climatic variables, has not been yet fully investigated. Use of Earth Observation data allows the identification of spatial and temporal variations of suspended sediments related to river runoff, seafloor erosion, sediment transport and deposition processes. The objective of this study is to investigate superficial processes in sedimentary depositional marine environment integrating in-situ data and remote sensing data. The developed innovative approach allow quantitative evaluation of sediment dynamics using Earth Observation data, by relating spatial and temporal patterns of sediment dispersal with climatic forcings.

PS InSAR Integrated with Geotechnical GIS: Some Examples from Southern Lombardia

The Oltrepo Pavese, which extends for almost 1100 km2 in Lombardia Region (Northern Italy), has a complex geological-structural setting resulting from overthrusting of different tectonic units made up mainly of clays. All these characteristics make the Oltrepo Pavese particularly vulnerable to hydrogeological risk: shallow and deep landslides in the hill, swelling/shrinkage of the clayey soils and subsidence in the plain. In order to understand more about the hydrogeological hazard (related to landslides and other phenomena) and related risk in the Oltrepo Pavese area the Regione Lombardia decided to test the use of the Permanent Scatterers Technique.