Surface deformation of active volcanic areas retrieved with the SBAS-DInSAR technique: an overview

This paper presents a comprehensive overview of the surface deformation retrieval capability of the Differential Synthetic Aperture Radar Interferometry (DInSAR) algorithm, referred to as Small BAseline Subset (SBAS) technique, in the context of active volcanic areas. In particular, after a brief description of the algorithm some experiments relevant to three selected case-study areas are presented. First, we concentrate on the application of the SBAS algorithm to a single-orbit scenario, thus considering a set of SAR data composed by images acquired on descending orbits by the European Remote Sensing (ERS) radar sensors and relevant to the Long Valley caldera (eastern California) area. Subsequently, we address the capability of the SBAS technique in a multipleorbit context by referring to Mt. Etna volcano (southern Italy) test site, with respect to which two different ERS data set, composed by images acquired both on ascending and descending orbits, are available. Finally, we take advantage of the capability of the algorithm to work in a multi-platform scenario by jointly exploiting two different sets of SAR images collected by the ERS and the Environment Satellite (ENVISAT) radar sensors in the Campi Flegrei caldera (southern Italy) area. The presented results demonstrate the effectiveness of the algorithm to investigate the deformation field in active volcanic areas and the potential of the DInSAR methodologies within routine surveillance scenario

FIFTEEN YEARS OF ERS AND ENVISAT DInSAR OBSERVATIONS AT MT. ETNA (ITALY) BY USING THE SBAS APPROACH

We exploited the Small BAseline Subset (SBAS) technique and computed ground displacement maps and time series by inverting 283 interferograms generated from the ascending and 289 from the descending orbits to reveal Mt. Etna surface deformation from 1992 to 2006. Our analysis shows that the volcano experienced magmatic inflation/deflation and radial spreading of the west, south and east flanks. In particular, the summit area vertical deformation inverted its sign after 2000 and clearly shows a deflation effect related to the 2001 and 2002 eruptive and seismic events. On the contrary, the horizontal signals revealed on the eastern and western flanks present significant and consistent motions toward east and west, respectively, during the investigated interval. Overall, the presented results show the complex and articulated deformation behavior of Mt. Etna and remark the possible coexistence of both gravity and magma forcing

The 2004–2006 uplift episode at Campi Flegrei caldera (Italy): Constraints from SBAS-DInSAR ENVISAT data and Bayesian source inference

We investigate the 2004–2006 uplift phase of Campi Flegrei caldera (Italy) by exploiting the archive of ascending and descending ENVISAT SAR data acquired from November 2002 to November 2006. The SBAS-DInSAR technique is applied to generate displacement mean velocity maps and time series. An appropriate post-processing step is subsequently applied to map the areas whose temporal deformation behavior is correlated with that of the maximum uplift zone. Our results show that the deformation also extends outside the volcanological limits of the Neapolitan Yellow Tuff caldera, without significant discontinuities. The DInSAR data are inverted by considering a finite spheroid and an isotropic pointsource. The inversion results suggest that the new uplift is characterized by a source location similar to the previous small uplift event of 2000 and to the long term subsidence of the 1990’s. In particular, the source is located at a depth of about 3.2 km and very close to the city of Pozzuoli (about 800 m offshore, to the SW); the associated volume variation is about 1.1 106 m3/year.PublishedL073081.10. TTC - TelerilevamentoJCR Journalreserve

Volcanic spreading of Vesuvius, a new paradigm for interpreting its volcanic activity

We integrate geologic, structural, leveling and Differential SAR Interferometry data to show that Vesuvius began to spread onto its sedimentary substratum about 3,600 years ago. Moreover, we model the detected deformation with a solution of the lubrication approximation of the Navier-Stokes equations to show that spreading may continue for about 7,200 years more. Correlation of volcanic spreading with phases of the eruptive activity suggests that Plinian eruptions, which are thought to pose the major hazard, are less likely to occur in the near future.Published1-4partially_ope

MONITORING THE CAMPI FLEGREI CALDERA BY EXPLOITING SAR AND GEODETICAL DATA: RECENT RESULTS AND FUTURE APPLICATIONS

Geodetical monitoring of the Campi Flegrei caldera (Naples, Italy), has been historically carried out by ground networks giving an information related only to a certain number of measuring points; this limitation can be greatly relieved by exploiting the space-borne DInSAR which allows to extract the geodetic information on wide areas, with a good time coverage in comparison with the mean repetition time of the campaign measurements. In this work we will show recent results on Campi Flegrei, obtained by using all the ENVISAT ASAR available data from both ascending and descending orbits. The processed data revealed that the uplift phase of Campi Flegrei, which became very clear in summer 2005 with an average velocity of about 2.8 mm/year, has definitely reduced the uplift velocity since spring 2007. This conclusion is consistent with independent deformation measurements carried out by the Vesuvius Observatory (INGV-OV). Differences, in terms of limits and potentialities of DInSAR with respect to classical geodetic techniques and vice-versa and the way they can be compared/integrated, is still a very interesting matter of debate suggesting, as an optimal solution for monitoring purposes in active volcanic areas, the integration of all the available techniques.UnpublishedFrascati1.10. TTC - Telerilevamentoope

Monitoring Actives Volcanoes by Using of Envisat and Ers Data: First Results of the Eurorisk-Preview Project

In the framework of the Eurorisk-Preview project, funded by the European Union, a task is dedicated to the assessment, prevention and management of volcanic risk. We are developing a multidisciplinary approach, integrating the geophysical prospecting at local scale and large scale remote sensing data. To achieve this task, two volcanic test sites have been identified: Mt. Etna, in Sicily (Italy), and Tenerife, in Canary Islands (Spain). We investigate the surface deformation and the volcanic emission in the atmosphere by using SAR series and multispectral data, requested in the ESA Category 1 (n. 3560). For Mt. Etna data from historical to recent eruptions (1992 – 2006) has been analysed while for Tenerife archived SAR data from 1992 to 2005 has been analysed, individuating anomaly ground deformations in Pico de Teide and surrounding areas as suggested by GPS campaigns

A QUANTITATIVE ASSESSMENT OF DInSAR TIME SERIES ACCURACY IN VOLCANIC AREAS: FROM THE FIRST TO SECOND GENERATION SAR SENSORS

We perform a quantitative assessment of the accuracy of Differential SAR Interferometry (DInSAR) time series in volcanic areas, retrieved through “first” and “second generation” SAR data. In particular, we analyze the impact that the wavelengths and looking geometries may have in the DInSAR measurement retrieval depending on the radar system. To this aim, we focus on the DInSAR algorithm referred to as Small BAseline Subset (SBAS) to generate mean deformation velocity maps and corresponding time series starting from sequences of SAR images. Moreover, we consider collections of SAR data acquired by the ERS-1/2 and ENVISAT (C-band), and COSMO-SkyMed (Xband) sensors over the volcanic area of the Campi Flegrei caldera, Southern Italy. We invert these SAR data sequences through the SBAS-DInSAR technique, thus obtaining C- and X- band deformation time series that we compare to continuous GPS measurements, the latter assumed as reference. The achieved results provide, in addition to a clear picture of the surface deformation phenomena already occurred and occurring in the selected case study, relevant indications for the analysis of the SBAS-DInSAR time series accuracies in volcanic areas passing from the first to second generation SAR sensors.PublishedMünich1IT. Reti di monitoraggio e Osservazionirestricte

Western Diet-Fed, Aortic-Banded Ossabaw Swine: A Preclinical Model of Cardio-Metabolic Heart Failure.

The development of new treatments for heart failure lack animal models that encompass the increasingly heterogeneous disease profile of this patient population. This report provides evidence supporting the hypothesis that Western Diet-fed, aortic-banded Ossabaw swine display an integrated physiological, morphological, and genetic phenotype evocative of cardio-metabolic heart failure. This new preclinical animal model displays a distinctive constellation of findings that are conceivably useful to extending the understanding of how pre-existing cardio-metabolic syndrome can contribute to developing HF

The VELISAR initiative for the measurement of ground velocity in italian seismogenic areas

VELISAR (Ground VELocity in Italian Seismogenic Areas) is a scientific research initiative aimed at producing a map of the ground deformation over most of the seismogenic areas of Italy, using the space-based technique of multitemporal Synthetic Aperture Radar Interferometry (InSAR). The ground velocities derived from InSAR data will be validated by means of ground based data obtained from GPS, optical leveling, seismological and neotectonic studies. The scope of the project is to produce a high-resolution ground deformation dataset useful to model the seismic cycle of strain accumulation and release at the scale of the single faults. The main objective of VELISAR is to produce maps of ground velocity with the following characteristics: - A ground resolution better than 100 m. - Average uncertainty of LoS velocity measurements smaller than 2 mm/yr . - Temporal coverage of at least 7 years. - Retrieval of East and Up components from ascending and descending LoS. VELISAR will exploit the potential of the long time series (1992-2000) of ERS InSAR data maintained in the ESA archives; over 4000 ERS images will have to be processed to accomplish its objectives. Presently, two InSAR techniques for the measurement of slow ground deformation are used in VELISAR: the Permanent Scatterers (PS) technique developed by the Politecnico of Milano (POLIMI), and the Small Baseline Subset (SBAS) technique, developed by the Institute for Remote Sensing of Environment (IREA-CNR), in Napoli. The PS technique is applied by TRE preferably over areas characterised by diffuse temporal decorrelation due to, for instance, erodible lithologies, agricultural land use and strong vegetation cover. In these areas we expect to obtain good temporal coherence mainly on sparse point scatterers. The SBAS technique is applied by IREA and INGV mostly over areas where limited temporal decorrelation is expected: urban areas, scarcely vegetated areas. The ground resolution at which these data are originally processed is 80 m. An important goal of the VELISAR initiative is to disseminate the information on the InSAR-derived ground velocity measurements, to the scientific community and to the public in general. Such goal is accomplished through a dedicated web site, where the velocity maps of the italian seismogenic areas will be progressively published. We will present the initiative, its scope and objectives, the technical details and the data processing strategies, and some examples of ground velocity maps.PublishedVienna, Austriaope