1,721,195 research outputs found
Surface displacements associated with the L'Aquila 2009 Mw 6.3 earthquake (central Italy): New evidence from SBAS-DInSAR time series analysis
No full textWe investigate the surface displacements in the area affected by the April 2009 L'Aquila earthquake (Central Italy) through an advanced DInSAR analysis. In particular, we apply the SBAS approach to retrieve deformation maps and displacement time series from ENVISAT data acquired between February 2003 and October 2009 and from COSMO-SkyMed data relevant to the six-month interval following the earthquake. Our analysis shows no evidence of pre-seismic surface deformation at the 35-day temporal sampling of the ENVISAT sensor. On the other hand, by benefiting of the high spatial resolution and temporal sampling of the COSMO-SkyMed satellites, we measure post-seismic displacements at an unprecedented level of detail for a DInSAR analysis. This allows us to identify three main areas continuing to deform after the earthquake. In addition, our modeling shows that post-seismic displacements are very likely related to the fault afterslip, since their decay times are on the order of 10(1)-10(2) days. Citation: Lanari, R., et al. (2010), Surface displacements associated with the L'Aquila 2009 Mw 6.3 earthquake (central Italy): New evidence from SBAS-DInSAR time series analysis, Geophys. Res. Lett., 37, L20309, doi:10.1029/2010GL044780. RI Manconi, Andrea/B-8367-2009; Sansosti, Eugenio/F-7297-2011; Casu, Francesco/H-3793-201
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On the capability of the SBAS-DInSAR technique to investigate deformation phenomena of large areas with low resolution data
No full textThe Extended SBAS Technique For Generating Long Term Full Resolution Ers/Envisat Deformation Time-Series
No full textOn the Exploitation of spaceborne Radar Interferometry for the Earth Surface Deformation Analysis: the Cagliari area case study
No full textLong-term ERS/ENVISAT deformation time-series generation at full spatial resolution via the extended SBAS technique
No full textWe extend the small baseline subset (SBAS) differential synthetic aperture radar (SAR) interferometry (DInSAR) approach to allow the generation of deformation time-series by processing, at the full spatial resolution scale, long sequences of European Remote Sensing (ERS-1 and ERS-2) and Environmental Satellite (ENVISAT) SAR data acquired with the same illumination geometry. In particular, we avoid the generation of ERS/ENVISAT cross-interferograms, which are severely affected by noise phenomena due to the carrier frequency separation of the two SAR systems, and we focus on single-platform interferograms only (i.e. ERS/ERS and ENVISAT/ENVISAT interferograms) that are properly combined by applying the singular value decomposition (SVD)-based SBAS approach. Moreover, we exploit the Doppler centroid variations of the post-2000 acquisitions of the ERS-2 sensor and the carrier frequency difference between the ERS-1/2 and the ENVISAT systems, in order to maximize the number of investigated SAR pixels and to improve their geocoding. The presented results, achieved on two data sets relevant to the Napoli Bay area and to the Murge region, both located in southern Italy, confirm the effectiveness of the extended SBAS technique and demonstrate the relevance of deformation analysis carried out at the scale of single buildings or human-made structures with more than 15 years of ERS and ENVISAT acquisitions
The extended SBAS technique for generating full resolution ERS/ENVISAT deformation time-series
No full textMETODO DI PRE-ELABORAZIONE AZIMUTALE DEI SEGNALI ACQUISITI DA UN RADAR AD APERTURA SINTETICA IN MODALITA' AD INQUADRAMENTO DI UNA SCENA
No full textL'invenzione riguarda un metodo per elaborare i dati Radar ad Apertura Sintetica (SAR) acquisiti in modalità ad inquadramento di una scena fissa, o spotlight. Tali dati consentono di ottenere immagini radar ad alta risoluzione della scena inquadrata. La tecnologia sviluppata consiste essenzialmente in una tecnica di pre-elaborazione (azimutale) che consente il successivo impiego (con modifiche marginali) dei già esistenti ed efficienti metodi di focalizzazione di dati acquisiti in modalità convenzionale (detta stripmap). La suddetta pre-elaborazione è realizzata in maniera efficiente poiché prevede solo moltiplicazioni complesse e Trasformate di Fourier
- …
