Search

Coastal regions are becoming increasingly vulnerable to flooding because of accelerating sea-level-rise (SLR), local ground subsidence, and the changes in topography and morphology. Moreover, coastal areas are usually highly urbanized and increased human activities have an effect on the stability and preservation of the environment. For instance, the growing demand for new lands to accommodate the population and the industrial facilities in China has required the design and the deployment of land-reclamation projects from the ocean, with a marked impact on fragile coastal eco-systems. Specifically, the Yangtze River and Pearl River Estuary, two major estuaries of the world, have long been subject to intensive human activities over the past decades. Long-term ground subsidence evolution, topographic changes, and morphological variation of the coastal regions have drawn great attention. This paper provides an overview of well-established Earth Observation (EO) remote sensing (RS) technologies that are employed to continuously monitor the changes of urbanized regions. The combined use of EO-based DInSAR analyses along with the knowledge of the geomorphology of the coastal regions allows a more precise picture of the SLR risk in the investigated coastal regions. In this paper, we will concentrate on remote sensing technologies that allow the gathering of heterogeneous information, such as those based on the use of synthetic aperture radar (SAR), satellite altimeters and tide gauge data. We will underline how human activities trigger changes in the living environment of coastal zones and the associated risks for the population. Observed coastline changes, coastal regions terrain subsidence, and offshore bathymetry have a pronounced effect on the increasing risk of flooding. Accordingly, we also present insights into some inundation model projections employed for evaluating the potential flooding risk in coastal regions.

The increasingly widespread use of space geodesy has resulted in numerous, high-quality surface deformation data sets. DInSAR, for instance, is a well-established satellite technique for investigating tectonically active and volcanic areas characterized by a wide spatial extent of the inherent deformation. These geodetic data can provide important constraints on the involved fault geometry and on its slip distribution as well as on the type and position of an active magmatic source. For this reason, over last years, many researchers have developed robust and semiautomatic methods for inverting suitable models to infer the source type and geometry characteristics from the retrieved surface deformations.In this work we will present a new software we have implemented, named easyGeoModels, that can be used by geophysicists but also by less skilled users who are interested in sources modeling to determine ground deformation in both seismo-tectonic and volcanic contexts. This software is characterized by some innovative aspects compared to existing similar tools, such as (i) the presence of an easy-to-use graphic interface that allows the user, even if not particularly expert, to manage the data to be inverted, the input parameters of one or more sources, the choice of the deformation source (s), effective and simple way; (ii) the possibility of selecting the GPS data to be inverted, simply by selecting the area of interest: in this case the software will automatically consider for the inversion only the GPS stations present in the selected area and will download the relative data from the Nevada Geodetic Laboratory site; (iii) the generation of output files in Geotiff, KMZ and Shapefile format, which allow a faster and more immediate visualization through GIS tools or Google Earth.Finally, as applications, we will show some preliminary results obtained through the easyGeoModels software on areas characterized by huge deformation both in a volcanic context, such as that of the Campi Flegrei caldera, and a seismo-tectonic one, as for the case of the Amatrice earthquake (central Italy) which occurred on 24 August 2016.

Questo documento presenta l'attività di sviluppo dell'applicativo software per la pianificazione automatica e rendicontazione delle attività progettuali. L'attività lavorativa svolta da ricercatori, tecnologi, tecnici ed altro personale ausiliario deve essere dichiarata in sede di rendicontazione economica, attraverso la compilazione di schede di rendicontazione (in seguito denominate timesheet ) in base all'impegno effettivo orario dedicato al progetto. I timesheet sono fogli di lavoro contenenti il dettaglio delle ore complessivamente lavorate dal dipendente, comprensivi delle informazioni di ferie, permessi e trasferte. Si è reso necessario progettare e implementare uno strumento informatico di supporto alle attività amministrative di rendicontazione al fine di rendere più agevole la compilazione di tali prospetti, precedentemente compilati prevalentemente in modo manuale.

Lo scopo di questo rapporto tecnico è la descrizione dell'attività svolta nell'ambito della realizzazione di easyGeoModels, un applicativo per la modellazione analitica delle sorgenti geofisiche a partire da dati DInSAR e GPS. L'Istituto per il Rilevamento Elettromagnetico dell' Ambiente (IREA) del Consiglio Nazionale delle Ricerche (CNR) si era dotato negli anni di codici software per la modellazione geofisica, che prevedevano per il loro utilizzo un continuo intervento dell'operatore. In particolare non era previsto un processo automatico che gestisse i passi dell'elaborazione in modo integrato ed esaustivo. Il presente lavoro ha avuto come obiettivo l'automatizzazione dei processi per la generazione di modelli diretti, di Inversione non lineare e lineare (Slip distribuito), mediante l'utilizzo di applicativi che riproducono la deformazione indotta in super ficie da sorgenti di deformazione ampiamente utilizzate dalla comunità scientifica, come quelle denominate di Okada, Penny-shaped crack, Mogi e Yang, a partire da osservazioni derivanti da dati satellitari. L'applicativo, integralmente realizzato nel linguaggio Interactive Data Language - IDL, corredato da una interfaccia grafica, permette di effettuare le modellazioni in modo agevole e senza intervento da parte dell'operatore, se non nella fase di ingestione delle informazioni di input

An intense volcano-tectonic crisis affected a part of Etna volcano from 24 to 27 December 2018; such event was analyzed and monitored by using the DInSAR technique, taking advantage from Sentinel-1 constellation and COSMO-SkyMed measurements to retrieve the observed deformation pattern.In particular, we used Sentinel-1 datasets acquired by ascending and descending orbits by with a 6 days revisit time and with the Interferometric Wide Swath (IWS) acquisition mode, referred to as Terrain Observation with Progressive Scans (TOPS). This volcano-tectonic crisis generated an intrusion dyke with an intense eruptive activity at summit craters accompanied by explosions and lava flows, modifying also part of the volcanic edifice and on 26 December 2018 an earthquake with M=4.9 localized on the lower part of the southeastern flank. We generated long-term deformation mean deformation velocity maps and the corresponding time series relevant to pre-event (April 2015-24 December 2018) and post-event (28 December 2018-March 2020). We exploited for the crisis two ascending and one descending orbits interferograms acquired from Sentinel-1 undergo to a multilook operation (5 and 20 pixels along the azimuth direction and range, respectively) to finally lead to a ground pixel size of about 70 by 70 meters. Furthermore, we combined ascending and descending orbits to obtain the East-West and Vertical components of the volcano edifice displacements.The main results show that the deformation on Etna summit craters and on eastern flank of edifice astride the eruptive event, causing a vertical deformation of about 50 cm and a jump of about 40 cm on horizontal component. These evidences are confirmed by East-West interferogram, whose maximum values exceed 30 cm towards the West and 40 towards the East on the summit of the volcano. Instead In the area in correspondence of the 26 December main shock, a maximum eastward and westward displacement of 12-14 cm and 15-17 cm is observed, respectively. In general, after December 27th the velocity map vertical and horizontal show a progressive attenuation of movements over time. For the eastern flank, horizontal displacements (eastwards) until to 10 cm were achieved in the months following the seismic-volcanic events of December 2018. In the region south-west of the Fiandaca structure, affected by the 4.9 MW earthquake, there is an almost stationary trend of the movement in the post-event period with a small movement of 1.5 cm towards the west in the last month. Finally, even the deformation of the area around the Elachea island currently shows a positive stationary trend (towards the east). On the western side, the trend of post-event displacement showed increases compared to the period preceding the event, although with generally smaller entities than on the eastern side. he progressive Tattenuation of the extent of the movement towards the west with time reaching about 7 cm in the last year is highlighted.This analysis allowed to Italian Civil Protection to follow the evolution in the last two years of volcano - tectonic crises and the scientific community to take relevant decisions about the level of emergency for the local population.

The Sentinel-1 constellation of the Copernicus Program already represents a big revolution within the Earth Observation (EO) scenario. This result is mainly due to the capability of this constellation to acquire huge volumes of SAR data all over the globe, with a wide spatial coverage, a short revisit time (12 or 6 days in the case of one or two operating satellites, respectively), and a free and open access data policy. In particular, the availability of such a large amount of SAR data acquired through the TOPS mode, characterized by a short “orbital tube” (with a 200m nominal diameter) and a specific design for ensuring differential SAR interferometry (DInSAR) applications, has opened the possibility to investigate Earth surface deformation phenomena at unprecedented spatial scale and with a high temporal rate. Among several advanced DInSAR algorithms, a widely used approach is the Small BAseline Subset (SBAS) technique, which has already proven its effectiveness to investigate surface displacements with centimeter- to millimeter-level accuracy in different scenarios. Moreover, a parallel algorithmic solution for the SBAS approach, referred to as Parallel Small BAseline Subset (P-SBAS), has been recently developed. This approach permits to generate, in an automatic and unsupervised way, advanced DInSAR products by taking full benefit from parallel computing architectures, such as cluster, grid and, above all, cloud computing infrastructures. In this work we present the results of a DInSAR experiment, based on the P-SBAS approach, carried out at the European scale. In particular, we exploited the entire available Sentinel-1 dataset collected through the TOPS acquisition mode between March 2015 and September 2018 from descending orbits over large part of Europe. Moreover, the overall analysis wasbcarried out by using the Copernicus Data and Information Access Services (DIAS) and, in particular, those provided by the ONDA DIAS platform, which was selected through a public tender. This activity, carried out as stress test of the EPOSAR service included in the Satellite Data Thematic Core Service of the EPOS infrastructure, permitted to investigate the DIAS capacity to operationally serve systematic and automatic DInSAR processing services, such as the one based on the P-SBAS approach. Our experiment was successfully completed, allowing the retrieval of the deformation time-series of the overall investigated area with the final products having the main characteristics summarized in the following: Exploited Sentinel-1 data: ~72.000 Covered Area: ~4.500.000 km2 Coherent (multilook) SAR pixels: ~120.000.000 Final products pixel dimension: ~80 m Time elapsed: ~6 months The presented discussion will highlight the main pros and cons of the exploited solution for such wide area DInSAR experiment. Moreover, the analysis of the achieved results will also show the high quality of the retrieved DInSAR results, that can be of interest for the Solid Earth scientific community, and the potentially positive impact of the presented solution for what concerns the future development of the European Ground Motion Service.This work is supported by: the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement; the H2020 EPOS-SP project (GA 871121); the I-AMICA (PONa3_00363) project; and the IREA-CNR/DGSUNMIG agreement.

We present an efficient tool for managing, visualizing, analysing, and integrating with other data sources, Earth Observation (EO) data for the analysis of surface deformation phenomena. In particular, we focused on specific EO data that are those obtained by an advanced-processing of Synthetic Aperture Radar (SAR) data for monitoring wide areas of the Earth's surface. More specifically, we refer to the SAR technique called advanced differential interferometric synthetic aperture radar (DInSAR) that have demonstrated its capabilities to detect, to map and to analyse the on-going surface displacement phenomena, both spatially and temporally, with centimetre to millimetre accuracy thanks to the generation of deformation maps and time-series. Currently, the DInSAR scenario is characterized by a huge availability of SAR data acquired during the last 25 years, now with a massive and ever-increasing data flow supplied by the C-band Sentinel-1 (S1) constellation of the European Copernicus program.Considering this big picture, the Spatial Data Infrastructures (SDI) becomes a fundamental tool to implement a framework to handle the informative content of geographic data. Indeed, an SDI represents a collection of technologies, policies, standards, human resources, and related activities permitting the acquisition, processing, distribution, use, maintenance, and preservation of spatial data. We implemented an SDI, extending the functionalities of GeoNode, which is a web-based platform, providing an open-source framework based on the Open Geospatial Consortium (OGC) standards. OGC makes easier interoperability functionalities, that represent an extremely important aspect because allow the data producers to share geospatial information for all types of cooperative processes, avoiding duplication of efforts and costs. Our implemented GeoNode-Based Platform extends a Geographic Information System (GIS) to a web-accessible resource and adapts the SDI tools to DInSAR-related requirements. Our efforts have been dedicated to enabling the GeoNode platform to effectively analyze and visualize the spatial/temporal characteristics of the DInSAR deformation time-series and their related products. Moreover, the implemented multi-thread based new functionalities allow us to efficiently upload and update large data volumes of the available DInSAR results into a dedicated geodatabase. We demonstrate the high performance of implemented GeoNode-Based Platform, showing DInSAR results relevant to the acquisitions of the Sentinel-1 constellation, collected during 2015-2018 over Italy.This work is supported by the 2019-2021 IREA CNR and Italian Civil Protection Department agreement; the H2020 EPOS-SP project (GA 871121); the I-AMICA (PONa3_00363) project; and the IREA-CNR/DGSUNMIG agreement.

When performing oceanography measurements, it is critical to assess the presence of the noise sources that could affect the measured data and lead to wrong interpretation of the results. This paper report the result of an oceanography survey conducted by ISMAR-CNR, Naples, in the north-eastern marine sector of the Ischia Island and assess the influence of EMI on the measured results. The analyzed measurements of the Electric and Magnetic fields showed values of the E up to 0.82 V/m and of B up to 85 μT. By assuming a standard conductor, an inductance L up to 47 Ω on the cable corresponding to an induced electromotive force of 1184 mV was calculated. Also the experimental data show the EMI increase in site where the Pearson index correlation is higher. The results demonstrate that in an oceanographic survey planning, a preliminary electromagnetic screening is advisable to optimize the measurement setup.

This work intends to present the main activities and the most significant results that the Institute for Electromagnetic Sensing of the Environment (IREA) of the National Research Council (CNR) has retrieved within the framework of its collaboration with the Ministry of Economic Development (MiSE) - Directorate-General for Safety of Mining and Energy Activities National Mining Office for Hydrocarbons and Georesources (DGS-UNMIG). In particular, the IREA-CNR/MiSE-DGS-UNMIG agreement aims at investigating surface deformation affecting the areas of the Italian territory of particular interest for the DGS-UNMIG through space-borne Differential SAR (Synthetic Aperture Radar) Interferometry (DInSAR) analysis and multi-parameters and multi-physics modelling. To this aim, we exploit SAR data acquired from the first- and second-generation sensors, processed via the advanced DInSAR technique known as SBAS (Small BAseline Subset) approach, to detect and follow the temporal evolution of the surface displacements via the generation of mean deformation velocity maps and corresponding time-series. More specifically, we focus on the SAR data collected along ascending and descending orbits by the Sentinel-1 constellation of the Copernicus Program of the European Union to map the whole Italian Peninsula during the 2015-2018 time interval, thus providing information on the spatial distribution of the retrieved ground displacements and their temporal evolution. Moreover, we model the geological and geophysical processes that characterize the geothermal reservoir of Casaglia site (Northern Italy), which is the selected study area. In particular, we proceed to the definition and implementation of a geological / structural database and the building of a 3D stratigraphic-structural model of the Casaglia area. This model represents the basis from which a model of circulation of fluids will be developed with the Finite Element method, which will mainly concern the study of spatio-temporal variations of stress and strain in the region outside the reservoir, and the evaluation of any correlations between seismicity and the circulation of fluids.

We are writing this comment because many aspects of the analysis presented by Nappi et al. (2018) are debatable. In particular, a major issue is relevant to the conclusion suggested by Nappi el al. (2018) about a seismogenic normal fault with northward dip. This finding is not well-founded because the authors do not really present a causative source model. In addition, their statement is clearly not consistent with the Differential Interferometric Synthetic Aperture Radar (DInSAR), Global Positioning System (GPS) and seismological measurements presented in the article previously published by De Novellis et al. (2018). Moreover, we also report an evident error in the geologic map proposed by Nappi et al. (2018, their fig. 3).

The causative source of the first damaging earthquake instrumentally recorded in the Island of Ischia, occurred on 21 August 2017, has been studied through a multiparametric geophysical approach. In order to investigate the source geometry and kinematics we exploit seismological, Global Positioning System, and Sentinel-1 and COSMO-SkyMed differential interferometric synthetic aperture radar coseismic measurements. Our results indicate that the retrieved solutions from the geodetic data modeling and the seismological data are plausible; in particular, the best fit solution consists of an E-W striking, south dipping normal fault, with its center located at a depth of 800 m. Moreover, the retrieved causative fault is consistent with the rheological stratification of the crust in this zone. This study allows us to improve the knowledge of the volcano-tectonic processes occurring on the Island, which is crucial for a better assessment of the seismic risk in the area.

La Campagna Oceanografica Sismica Magnetica Elettrica Ischia (denominata "COSMEI") è nata a seguito dell'evento sismico verificatosi alle 20:57 del 21 agosto 2017 Mw 3.9 con epicentro nell'area di Casamicciola, con lo scopo di fornire ulteriori contributi nell'individuazione di strutture vulcano-tettoniche attive nel settore nord marino dell'isola d'Ischia. Il CNR-DTA nell'ambito di tali attività ed in concomitanza delle attività del Centro per la Microzonazione Sismica e delle sue applicazioni (centro MS), ha disposto un piano di indagini a mare necessarie per la ricostruzione di strutture tettoniche e vulcaniche potenzialmente origine di eventi sismici. La campagna oceanografica COSMEI dell'IAMC-CNR di Napoli, ha predisposto rilievi geofisici di tipo sismico multicanale, magnetico differenziale, di resistività elettrica, Chirp e Multibeam nel settore marino nord-orientale dell'isola d'Ischia. Le attività di acquisizione sono state condotte utilizzando la N/O Minerva Uno del Consiglio Nazionale delle Ricerche (CNR). L'obiettivo finale di tale studio è quello di fornire nuovi elementi geofisici finalizzati a migliorare la conoscenza dell'evoluzione geologica di questo settore dell'isola. In tale contesto, l'interpretazione geologico-strutturale dei profili sismici multicanale combinata col dato magnetometrico e di resistività elettrica ha lo scopo di migliorare la conoscenza dell'area nord-orientale dell'isola che risulta controllata da complessi vulcano-tettonici.

The advanced DInSAR technique referred to as Small BAseline Subset (SBAS) algorithm has already largely demonstrated its effectiveness to carry out multi-scale and multi-platform surface deformation analyses relevant to both natural and man-made hazards. Thanks to its capability to generate displacement maps and long-term deformation time series at both regional (low resolution analysis) and local (full resolution analysis) spatial scales, it allows to get more insights on the spatial and temporal patterns of localized displacements relevant to single buildings and infrastructures over extended urban areas, with a key role in supporting risk mitigation and preservation activities. The extensive application of the multi-scale SBAS-DInSAR approach in many scientific contexts has gone hand in hand with new SAR satellite mission development, characterized by different frequency bands, spatial resolution, revisit times and ground coverage. This brought to the generation of huge DInSAR data stacks to be efficiently handled, processed and archived, with a strong impact on both the data storage and the computational requirements needed for generating the full resolution SBAS-DInSAR results. Accordingly, innovative and effective solutions for the automatic processing of massive SAR data archives and for the operational management of the derived SBAS-DInSAR products need to be designed and implemented, by exploiting the high efficiency (in terms of portability, scalability and computing performances) of the new ICT methodologies. In this work, we present a novel parallel implementation of the full resolution SBAS-DInSAR processing chain, aimed at investigating localized displacements affecting single buildings and infrastructures relevant to very large urban areas, relying on different granularity level parallelization strategies. The image granularity level is applied in most steps of the SBAS-DInSAR processing chain and exploits the multiprocessor systems with distributed memory. Moreover, in some processing steps very heavy from the computational point of view, the Graphical Processing Units (GPU) are exploited for the processing of blocks working on a pixel-by-pixel basis, requiring strong modifications on some key parts of the sequential full resolution SBAS-DInSAR processing chain. GPU processing is implemented by efficiently exploiting parallel processing architectures (as CUDA) for increasing the computing performances, in terms of optimization of the available GPU memory, as well as reduction of the Input/Output operations on the GPU and of the whole processing time for specific blocks w.r.t. the corresponding sequential implementation, particularly critical in presence of huge DInSAR datasets. Moreover, to efficiently handle the massive amount of DInSAR measurements provided by the new generation SAR constellations (CSK and Sentinel-1), we perform a proper re-design strategy aimed at the robust assimilation of the full resolution SBAS-DInSAR results into the web-based Geonode platform of the Spatial Data Infrastructure, thus allowing the efficient management, analysis and integration of the interferometric results with different data sources.

TCS Satellite Data is devoted to provide Earth Observation (EO) services, transversal with respect to the large EPOS community, suitable to be used in several application scenarios. In particular, the main goal is to contribute with mature services that have already well demonstrated their effectiveness and relevance in investigating the physical processes controlling earthquakes, volcanic eruptions and unrest episodes as well as those driving tectonics and Earth surface dynamics. The TCS Satellite Data will provide two kinds of services: satellite products/services, and Value-added satellite products/services. The satellite products/services are composed of three (EPOSAR, GDM and COMET) well- identified and partly already operational elements for delivering Level 1 products. Such services will be devoted to the generation of SAR interferograms, DTM and ground displacement maps through the exploitation of different advanced EO techniques for InSAR and optical data analysis. The Value-added satellite products/services are composed of 4 elements (EPOSAR, 3D-Def, Mod and COMET) of Level 2 and 3 products. Such services integrate satellite and in situ measurements and observations to retrieve information on source mechanism, such as the geometry (spatial location, depth, volume changes) and the physical parameters of the deformation sources, through the exploitation of modelling approaches. The TCS Satellite Data will provide products in two different processing and delivery modes: 1- surveillance mode - routinely product generation; 2- on demand mode - product generation performed on demand by the user. Concerning the surveillance mode, the goal is providing continuous satellite measurements in areas of par- ticular interest from a geophysical perspective (supersites). The objective is the detection of displacement patterns changing along time and their geophysical explanation. This is a valid approach for inter-seismic movements and volcanic unrest, post-seismic and post-eruptive displacements, urban subsidence, coastal movements. The on demand mode will allow users to process available satellite data-stack by selecting the scenes and the area of interest, and properly setting some processing parameters or to perform modelling analyses. This processing mode will guarantee the possibility to analyse areas of interest for the users, thus exploiting as much as possible the global coverage strategy of satellites, as well as performing user-driven processing, benefiting from the knowledge of the characteristics of the particular investigated area and/or deformation phenomenon.

We investigate the surface deformation of the eastern California area that includes Long Valley caldera and Mono Basin. We apply the SAR Interferometry (InSAR) algorithm referred to as Small BAseline Subset (SBAS) approach that allows us to generate mean deformation velocity maps and displacement time series for the investigated area. The results presented in this work represent an advancement of previous InSAR studies of the area that are mostly focused on the deformation affecting the caldera. In particular, the proposed analysis is based on 21 SAR data acquired by the ERS-1/2 sensors during the 1992–2000 time interval, and demonstrates the capability of the SBAS procedure to identify and analyze displacement patterns at different spatial scales for the overall area spanning approximately 5000 km2. Two previously unreported localized deformation effects have been detected at Paoha Island, located within the Mono Lake, and in the McGee Creek area within the Sierra Nevada mountains, a zone to the south of the Long Valley caldera. In addition a spatially extended uplift effect, which strongly affects the caldera, has been identified and analyzed in detail. The InSAR results clearly show that the displacement phenomena affecting the Long Valley caldera have a maximum in correspondence of the resurgent dome and are characterized by the sequence of three different effects: a 1992–1997 uplift background, a 1997–1998 unrest phenomenon and a 1998–2000 subsidence phase. Moreover, the analysis of the retrieved displacement time series allows us to map the extent of the zone with a temporal deformation behavior highly correlated with the detected three-phases deformation pattern: background uplift-unrest-subsidence. We show that the mapped area clearly extends outside the northern part of the caldera slopes; accordingly, we suggest that future inversion models take this new evidence into account. The final discussion is dedicated to a comparison between the retrieved InSAR measurements and a set of GPS and leveling data, confirming the validity of the results achieved through the SBAS-InSAR analysis.

We present an overview of the Differential SAR Interferometry algorithm referred to as Small BAseline Subset (SBAS) technique, that allows us to detect surface deformation and to analyze their space-time characteristics. Following the description of the main theoretical aspects of the algorithm, we present several results obtained by applying the SBAS approach in selected case studies relevant to phenomena affecting volcanic areas (Campi Flegrei caldera and Somma-Vesuvio complex, Italy), aquifers (Santa Clara area within the San Francisco bay, California) and landslides (Maratea Valley, Italy). The overall analysis is carried out by using multilook DInSAR interferograms with a spatial resolution of the order of 100 × 100 m, computed from SAR data acquired by the ERS-1 and ERS-2 sensors. In particular, we highlight the peculiarities of the SBAS technique and its surface deformation retrieval capability for what concerns both large-scale deformation phenomena and more localized displacement effects.

In this study Differential Interferometric Synthetic Aperture Radar (DInSAR) is used to investigate the effects of a subsidence phenomenon – related to groundwater withdrawal –on ancient low‐rise masonry buildings located in the urban area of Sarno, Italy. ERS‐1/2 SAR data from 1992 to 2002 were analysed and results were validated with geodetic data. The results encourage future developments for study and use of the multi‐temporal DInSAR technique in the mitigation of subsidence risk.

The island of Ischia, located at the northwestern end of the Gulf of Napoli (Italy), is a volcanic area that is historically active (the Arso eruption, in 1302 and the Casamicciola earthquake, in 1883) and has diffuse hydrothermal phenomena. We present in this work a study of the surface deformation occurring in the island, which is based on applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) algorithm referred to as Small BAseline Subset (SBAS) technique. This study is focused on the 1992–2003 time interval and SAR data acquired by the European Remote Sensing (ERS) satellites from ascending and descending orbits have been used, thus allowing us to discriminate the vertical and east–west components of the displacements. A validation of the DInSAR results has been carried out first by comparing the vertical deformations estimated from the SAR data with those measured from the spirit leveling network that is present in the area. In particular, we computed the difference between the mean vertical deformation velocities estimated from the SAR and the corresponding geodetic measurements along three main leveling lines; the maximum value of the root mean square difference is of about 1 mm/yr. The final discussion is dedicated to the interpretation of the detected displacements, benefiting from the overall information extracted from the ascending and descending DInSAR measurements. In particular, DInSAR data relative to the vertical deformation component show that the present-day subsidence of Ischia mainly develops in areas characterized by active landsliding and along faults; moreover, the deflation of the island, which is recorded by the horizontal displacement component, is probably related to the de-pressurization of the hydrothermal system.

Differential Interferometric Synthetic Aperture Radar (DIFSAR) data have been integrated in a Geographic Information System (GIS) for investigating deformations occurring in urban areas. The proposed approach is based on an extension of the Small Baseline Subset (SBAS) method that allows a proper combination of a large number of DIFSAR data. The obtained deformation measurements are accurately geocoded to achieve an easy merging of DIFSAR products relative to different acquisition geometries and the integration of such products into a GIS. This allows the detection and analysis of displacements of single structures and buildings in the investigated zone. The effectiveness of the approach has been tested on the SAR data acquired by the European Remote Sensing (ERS) satellites relative to the Vomero hill, a district of the city of Naples, Italy.

We studied the Yellowstone caldera geological unrest between 1977 and 2010 by investigating temporal changes in differential Interferometric Synthetic Aperture Radar (InSAR), precise spirit leveling and gravity measurements. The analysis of the 1992–2010 displacement time series, retrieved by applying the SBAS InSAR technique, allowed the identification of three areas of deformation: (i) the Mallard Lake (ML) and Sour Creek (SC) resurgent domes, (ii) a region close to the Northern Caldera Rim (NCR), and (iii) the eastern Snake River Plain (SRP). While the eastern SRP shows a signal related to tectonic deformation, the other two regions are influenced by the caldera unrest. We removed the tectonic signal from the InSAR displacements, and we modeled the InSAR, leveling, and gravity measurements to retrieve the best fitting source parameters. Our findings confirmed the existence of different distinct sources, beneath the brittle-ductile transition zone, which have been intermittently active during the last three decades. Moreover, we interpreted our results in the light of existing seismic tomography studies. Concerning the SC dome, we highlighted the role of hydrothermal fluids as the driving force behind the 1977–1983 uplift; since 1983–1993 the deformation source transformed into a deeper one with a higher magmatic component. Furthermore, our results support the magmatic nature of the deformation source beneath ML dome for the overall investigated period. Finally, the uplift at NCR is interpreted as magma accumulation, while its subsidence could either be the result of fluids migration outside the caldera or the gravitational adjustment of the source from a spherical to a sill-like geometry.

We have illustrated the key results of the Differential SAR Interferometry (DInSAR) analysis focused on the ground deformation of Long Valley caldera and Mono Basin, eastern California. In particular, we have applied the DInSAR algorithm referred to as Small BAseline Subset (SBAS) approach and processed 21 SAR images, spanning the time interval from 1992 to 2000, acquired from descending arbits by the ERS-1 and ERS-2 sensors of the European Space Agency (ESA). The deformation affecting the resurgent dome of Long Valley caldera has been highlighted as well as the previously unreported subsidence of the Pahoa island, located in Mono Lake.

We present an enhanced version of the SBAS-DInSAR processing chain, which complements the conventional SBAS codes with a simple noise-filtering procedure that allows us to mitigate noise artifacts affecting the sequence of multi-look (multi-temporal) small baseline interferograms used within the SBAS inversion. We demonstrate that the use of such a noise-filtering algorithm permits to significantly improve the quality of the mean deformation velocity maps and displacement time-series retrieved via the SBAS-DInSAR processing chain, thus promoting more detailed analyses of the detected deformation phenomena. The overall effectiveness of the enhanced SBAS-DInSAR approach is confirmed by the experimental results achieved by applying the proposed method to two sets of SAR data collected by the ERS-1/2 and ENVISAT sensors over the Mt. Etna volcano (Southern Italy) and Yellowstone caldera (Wyoming, U.S.).

Advanced techniques of multi-pass space-borne Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) represent a valuable tool in landslide studies allowing to remotely investigate the behavior of mass movements on long time intervals by benefiting of large datasets of SAR images covering the same area and acquired at different epochs. Among these techniques, we apply the Small BAseline Subset (SBAS) approach for analyzing surface deformation at two spatial scales, i.e., regional and local scale.

This work shows a methodological approach for the joint use of geological and geomorphological studies and conventional/innovative monitoring data in densely urbanized areas at landslide risk. The methodology is applied to a test area in the Calabria region (southern Italy) extensively affected by several active landslides involving urban areas. These landslides have been studied and monitored via ground-based techniques for many years. In the study area the comparison and interpretation of DInSAR data with geomorphological studies and inclinometric monitoring has been carried out. The results obtained, thanks to the validation of remote sensed data via ground-truths, provide a further step towards the integrated use of DInSAR data within landslide risk mitigation strategies. © Springer-Verlag Berlin Heidelberg 2013.