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Castelldefels, Spain

Intrieri E.,University of Florence | Di Traglia F.,University of Florence | Di Traglia F.,University of Pisa | Del Ventisette C.,University of Florence | And 4 more authors.
Geomorphology | Year: 2013

Stromboli is characterized by frequent explosions of variable energy and periodically interrupted by more energetic blasts emitting large volumes of material. The pressurization of a volatile-poor, high-porphyritic magma column that is gas-recharged by the deep-seated, volatile-rich, low-porphyritic magma precedes such events and produces deformations on the NW flank of the volcano, Sciara del Fuoco. By integrating geomorphological observations with long-term displacements from ground-based interferometric radar since December 2007, we identified two landslides whose movements are strongly related with volcanic activity. Movement patterns obtained through a novel long-term analysis of GB-InSAR data permitted us to hypothesize the type of movement and depth for both landslides. Furthermore their position allowed us to affirm that the effusive vent formed in 2007 at 400. m. a.s.l., was the result of the deflection of a feeder dike caused by landslide fractures, thus showing the important role of geomorphological discontinuities in volcanic environments. © 2013 Elsevier B.V. Source

Dalla Via G.,Polytechnic of Milan | Crosetto M.,Institute of Geomatics | Crippa B.,University of Milan
Journal of Geophysical Research: Solid Earth | Year: 2012

Analysis of surface coseismic displacement has already been obtained for the 6 April 2009L'Aquila (central Italy) earthquake from differential interferometric synthetic aperture radar (DInSAR) data. Working jointly on ascending and descending DInSAR data makes for a step forward with respect to published preliminary estimates: we process data in order to retrieve a continuous displacement pattern, both in the vertical and horizontal directions, the latter being limited to the eastward component because of the low sensibility of the SAR images used to resolve northward motion. Our analysis provides new insights on the horizontal component of displacement, obtaining a clear picture of eastward displacement patterns over the epicentral area. This result is noteworthy, as until now little information has been available on horizontal displacement following normal-fault events in the central Apennines (Umbria-Marche, 1997, and L'Aquila, 2009), given the lack of dense GPS networks, the only available source of horizontal displacement data in this area. Inverted fault characteristics from such data also show noteworthy differences compared to previous studies, localizing the Paganica fault as the causative fault for the earthquake. Copyright 2012 by the American Geophysical Union. Source

Blazquez M.,Institute of Geomatics | Colomina I.,Institute of Geomatics
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2012

Over the past two decades, the development of Global Navigation Satellite System (GNSS) technology, inertial navigation technology and Inertial Navigation Systems (INS) and their application to sensor orientation in photogrammetry and remote sensing has led to more precise, accurate, reliable and cost efficient orientation and calibration methods and procedures. Today, most airborne photogrammetric and remote sensing systems are equipped with GNSS receivers and inertial sensors. To a large extent and more or less independently from the imaging geometry and sensor type, orientation is performed with the " direct" and " integrated" methods. In this paper we introduce a new orientation method that we call " Fast AT" for frame images. The new method combines image measurements, ground control and aerial control observations in novel quantitative and qualitative ways. Depending on project specifications, Fast AT can be a robust alternative to direct orientation and, at the very least, a fast quality control tool for any orientation task. We analyze the performance of Fast AT with analogue and digital frame imagery and draw conclusions on its general properties. © 2012 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Source

Blazquez M.,Institute of Geomatics | Colomina I.,Institute of Geomatics
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2012

In this paper we present the models and discuss the performance of relative position and attitude INS/GNSS aerial control observations in integrated sensor orientation. In relative aerial control, we use the relative position and attitude of the IMU at the exposure times of successive images instead of the usual absolute position and attitude for each image. With relative aerial control, the GNSS shift correction parameters and the IMU-to-camera boresight matrix vanish from the functional models and so does the problem of their selection. The presented models are formulated with the usual original INS/GNSS attitude parameterisation (heading, pitch and roll) to avoid unnecessary and error-prone intermediate re-parameterisation steps. Furthermore, we present a rigorous model formulation, for both aerial control and photogrammetric observations, in local mapping coordinate systems that eliminate the need of the so-called height and azimuth corrections and that guarantee geodetic correctness and consistency. The overall resulting modelling scheme allows for a direct incorporation of INS/GNSS aerial control observations into the integrated sensor orientation processing chain in a simple and robust way. The performance of the new models is evaluated with three independent data sets and the results show a comparable to better performance. © 2011 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Source

Crosetto M.,Institute of Geomatics | Monserrat O.,Institute of Geomatics | Iglesias R.,Institute of Geomatics | Crippa B.,University of Milan
Photogrammetric Engineering and Remote Sensing | Year: 2010

This paper is focused on the potential and limits of Persistent Scatterer Interferometry (PSI), a powerful remote sensing technique used to measure deformation phenomena. It only refers to satellite-based PSI techniques, focusing on the most important sources of C-band SAR data: ERS and Envisat. In addition, it compares C- and X-band results, considering data from the high-resolution TerraSAR-X sensor. The paper begins with a description of the main characteristics of PSI. It then discusses the most important PSI products and their performances, analyzing their spatial sampling, the so-called residual topographic error and PSI geocoding, the average displacement rates, and the deformation time series. As C-band products are concerned, the paper reports some relevant PSI validation results, which come from the ESAfunded Terrafirma Validation Project. Regarding the X-band, it describes the results obtained over the City of Barcelona by processing 13 TerraSAR-X images. The last part discusses the main limits of PSI. © 2010 American Society for Photogrammetry and Remote Sensing. Source

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