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  • 1
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    La Rete Integrata Nazionale GPS (RING): stato dell'arte a due anni dalla nascita (2008)
    Details
    Publication Date: 2017-04-04
    Description: Le reti permanenti GPS costituiscono una importante risorsa per una serie di studi tecnologici e scientifici. La carenza di conoscenze in studi di tettonica attiva, che comprendono anche la parte di sismologia come l'accumulo di deformazione sulle faglie, è stata a lungo frenata dalla mancanza di reti permanenti GPS sufficientemente dense distribuite su tutto il territorio nazionale. In particolare, la definizione di una placca Adriatica e la sua terminazione meridionale sono ancora materia di dibattito (Oldow et al., 2002; Battaglia et al. 2004). Inoltre, di recente, alcuni importanti lavori (Hollenstein, et al. 2004; D'Agostino and Selvaggi; Serpelloni et al. 2005) hanno mostrato che valori di deformazione molto più alti di quanto si pensava prima sono stati effettivamente riscontrati nella nostra regione e che solo l'uso di una rete densa di stazioni, quindi di un campionamento ad alta densità nelle aree dove sono maggiori le velocità relative, permette di osservare in modo corretto il rilascio, o accumulo, di deformazione. Infine, il contributo della geodesia alla sismologia sta diventando sempre più importante sia nella definizione del rilascio cosismico durante un terremoto e sia nell'osservazione e modellazione dell'accumulo intersismico di deformazione elastica su faglie attive. Da qualche anno, l'Istituto Nazionale di Geofisica e Vulcanologia (INGV) ha impiegato notevoli risorse e sforzi per rispondere a tali temi scientifici. Selvaggi et al. (2006) hanno gettato le basi e mostrato i primi sviluppi di una rete GPS permanente, la Rete Integrata Nazionale GPS (RING), creata con l'obiettivo di dare un forte contributo scientifico ai temi sopra citati La rete RING (Fig. 1a), nella sua completezza, rappresenta ad oggi non solo un punto di riferimento per studi di carattere scientifico ma anche una robusta infrastruttura tecnologica e informatica per l'archiviazione dei dati GPS per diverse altre reti locali e regionali (Regione Puglia, Regione Friuli, Leica Geosystems). Tali reti, contribuiscono quotidianamente all'acquisizione, all'interno di un server, di dati per un totale di oltre 300 stazioni distribuite sul territorio nazionale (Fig. 1b). Se, poi, si considera anche l'aspetto del processamento dei dati GPS, l'utilizzo di dati GPS appartenenti ad altre reti (locali, regionali o anche esterne al territorio italiano) fa sì che ogni analista utilizzi i dati, in media, di circa 650 stazioni GPS permanenti al giorno.
    Description: Published
    Description: L'Aquila - Italia
    Description: 1.9. TTC - Rete GPS nazionale
    Description: reserved
    Keywords: Geodesy ; GPS ; RING Network ; Tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 2
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    Data Analysis of Permanent GPS networks in Italy (2009)
    Details
    Publication Date: 2017-04-04
    Description: Starting from 2004, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) set up a dense GPS network, called RING (Rete Integrata Nazionale GPS) in Italy in order to improve the knowledge of the geodynamics and tectonic processes. Due to the complexity of the tectonic behaviour in the area, the INGV also arranged the data analysis of all the permanent sites available in the Italian region. We will present time series and velocity fields obtained with two different processing software (GAMIT and BERNESE), analyzing the complete data set from 1998 to 2008 of over 300 sites. The processing is performed adopting a distributed session approach, with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions are routinely produced for each cluster and the velocity fields are obtained by stacking the daily normal equations rigorously. Residuals and differences between the two solutions will be presented and discussed. The comparison of the two geodetic solutions is an important tool to validate the results and to isolate systematic errors induced by the analysts and it is the first step to obtain a consensus solution of the Italian region.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 1.9. Rete GPS nazionale
    Description: open
    Keywords: GPS ; Italian Permanent Networks ; RING ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 3
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    An algorithm for the search of homogeneous strain-rate fields (2009)
    Details
    Publication Date: 2017-04-04
    Description: The aim of this paper is to describe the theoretical fundamentals and the main features of a software suitably implemented to estimate the strain-rate tensor from continuous GPS data. Current softwares developed for geophysical applications generally estimate or compute bi-dimensional strain, since this is the most requested use. On the contrary, this software allows for a three-dimensional estimate of the strain-rate tensor. It accounts for all the significant GPS velocities and estimates the strain-rate components by the least squares method starting from the hypothesis of one homogeneous strain-rate field. An initial field has to be defined by at least 4 sites which pass the chi-squared test on the strain-rate homogeneity. The developed algorithm automatically searches for sites belonging to this initial homogeneous field, starting from the site nearest to the barycentre of the first 4 sites and proceeding until a user-defined limit distance. Each time a site is added, the homogeneity of the whole field is suitably tested by a number of statistic tests. In this work the algorithm has been also applied to some areas of geophysical interest.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 1.9. Rete GPS nazionale
    Description: open
    Keywords: Strain-Rate ; GPS ; Statistical Tests ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 4
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    Coseismic deformation of the destructive April 6, 2009 L’Aquila earthquake (central Italy) from GPS data (2010)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: On April 6, 2009, 01:32:39 GMT, the city of L’Aquila was struck by a Mw 6.3 earthquake that killed 307 people, causing severe destruction and ground cracks in a wide area around the epicenter. Four days before the main shock we augmented the existing permanent GPS network with five GPS stations of the Central Apennine Geodetic Network (CaGeoNet) bordering the L’Aquila basin. The maximum horizontal and vertical coseismic surface displacements detected at these stations was 10.39 ± 0.45 cm and 15.64 ± 1.55 cm, respectively. Fixing the strike direction according to focal mechanism estimates, we estimated the source geometry with a non linear inversion of the geodetic data.Our best fitting fault model is a 13 15.7 km2 rectangular fault,SW-dipping at 55.3 ± 1.8 , consistent with the position of observed surface ruptures. The estimated slip (495 ± 29 mm) corresponds to a 6.3 moment magnitude, in excellent agreement with seismological data.
    Description: Published
    Description: L17307
    Description: 1.9. Rete GPS nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: L'Aquila Earthquake ; GPS ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Current geodetic deformation in the South Africa region (2009)
    Details
    Publication Date: 2017-04-04
    Description: We present a preliminary velocity field of the African continent derived from continuous GPS observations from 2004 to 2008. The aim of our work is to investigate the strain-rate pattern along the East Africa rift, in particular along the boundary of the two African plates (the Nubian and the Somalian) and in the South Africa region. We have processed GPS data in a time window spanning four years, i.e. from 2004 to 2008, involving IGS, TrigNet (a network of permanent GPS stations distributed throughout South Africa) and other sporadic sites. The GPS data have been processed by means of the Bernese software version 5.0 dividing the entire African network into two clusters. The combination of daily loosely constrained solutions provides the time series of about a hundred of permanent GPS sites mainly located in the African continent. Site velocities together with periodic signals, eventual steps, have been estimated simultaneously using the complete covariance matrices. Finally the velocity field has been expressed in the ITRF2005 reference frame. This investigation gives a preliminary idea of the velocity field and strain-rate pattern we can expect in the South-East Africa region, the observed deformations being barely measurable, below a few mm/year.
    Description: Unpublished
    Description: Vienna - Austria
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: open
    Keywords: GPS ; TrigNet Network ; South Africa ; Deformation ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 6
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    Modeling ground deformations of Panarea volcano hydrothermal/geothermal system (Aeolian Islands, Italy) from GPS data. (2009)
    Details
    Publication Date: 2017-04-04
    Description: Panarea volcano (Aeolian Islands, Italy) was considered extinct until November 3, 2002 when a submarine gas eruption began in the area of the islets of Lisca Bianca, Bottaro, Lisca Nera, Dattilo and Panarelli, about 2.5 km east of Panarea Island. The gas eruption decreased to a state of low degassing by July 2003. Before 2002 the activity of Panarea volcano was characterized by mild degassing of hydrothermal fluid. The compositions of the 2002 gases and their isotopic signatures suggested that the emissions originated from a hydrothermal/geothermal reservoir fed by magmatic fluids. We investigate crustal deformation of Panarea volcano using the GPS velocity field obtained by the combination of continuous and episodic site observations of the Panarea GPS network in the time span 1995-2007. We present a combined model of Okada sources which explains the GPS results acquired in the area after December 2002. The kinematics of Panarea volcano show two distinct active crustal domains characterized by different styles of horizontal deformation, supported also by volcanological and structural evidences. A subsidence in the order of several mm/yr is affecting the entire Panarea volcano and a shortening of 10-6 yr-1 has been estimated in the Islets area. Our model reveals that the degassing intensity and distribution are strongly influenced by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes in the regional stress field as suggested by the geophysical and volcanological events that occurred on 2002 in the Southern Tyrrhenian area.
    Description: In press
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: Panarea ; GPS ; Modelling ; gas eruption ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Co-seismic displacements associated to the Molise (Southern Italy)earthquake sequence of October–November 2002 inferred from GPS measurements (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2002 earthquake sequence of October 31 and November 1 (main shocks Mw=5.7) struck an area of the Molise region in Southern Italy. In this paper we analyzed the co-seismic deformation related to the Molise seismic sequence, inferred from GPS data collected before and after the earthquake, that ruptured a rather deep portion of crust releasing a moderate amount of seismic energy with no surface rupture. The GPS data have been reduced using two different processing strategies and softwares (Bernese and GIPSY) to have an increased control over the result accuracy, since the expected surface displacements induced by the Molise earthquake are in the order of the GPS reliability. The surface deformations obtained from the two approaches are statistically equivalent and show a displacement field consistent with the expected deformation mechanism and with no rupture at the surface. In order to relate this observation with the seismic source, an elastic modeling of fault dislocation rupture has been performed using seismological parameters as constraints to the model input and comparing calculated surface displacements with the observed ones. The sum of the seismic moments (8.9×1017 Nm) of the two main events have been used as a constraint for the size and amount of slip on the model fault while its geometry has been constrained using the focal mechanisms and aftershocks locations. Since the two main shocks exhibit the same fault parameters (strike of the plane, dip and co-seismic slip), we modelled a single square fault, size of 15 km×15 km, assumed to accommodate the whole rupture of both events of the seismic sequence. A vertical E–W trending fault (strike=266°) has been modeled, with a horizontal slip of 120 mm. Sensitivity tests have been performed to infer the slip distribution at depth. The comparison between GPS observations and displacement vectors predicted by the dislocation model is consistent with a source fault placed between 5 and 20 km of depth with a constant pure right-lateral strike-slip in agreement with fault slip distribution analyses using seismological information. The GPS strain field obtained doesn't require a geodetic moment release larger than the one inferred from the seismological information ruling out significant post-seismic deformation or geodetic deformation released at frequencies not detectable by seismic instruments. The Molise sequence has a critical seismotectonic significance because it occurred in an area where no historical seismicity or seismogenic faults are reported. The focal location of the sequence and the strike-slip kinematics of main shocks allow to distinguish it from the shallower and extensional seismicity of the southern Adriatic block from the northern one.
    Description: Published
    Description: 21-35
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; molise earthquake ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 1535914 bytes
    Format: application/pdf
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  • 8
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    Volcanic unrest of the Colli Albani (central Italy) detected by GPS monitoring test (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Colli Albani volcanic complex, located in central Italy about 15km SE of Rome, has been dominated by periodic eruptive histories started about 561 ka and ending with the most recent and voluminous activity of the Albano maar (〈70 ka) phase. Earthquakes of moderate intensity, gas emissions and significant ground deformations are the recent evidences of a residual activity. We decided to start a monitoring test by installing as first step three GPS permanent stations on the volcanic structure, in sites easily accessible. The analysis of about 2 years of GPS observations has evidenced a peculiar velocity pattern of the Colli Albani stations with respect to those located nearby, but outside the volcano edifice. With respect to Eurasia, the horizontal velocities are NE directed with magnitudes of 2.2±1.4mm/year (RDPI), 3.0±0.8mm/year (RMPO) and 3.3±1.2mm/year (NEMI). The uplift rates are determined with minor accuracy and range from 3.3 and 6.0mm/year. We used a non-linear inversion algorithm to determine the best-fit parameters for a Mogi spherical source based on the Levenberg–Marquardt least squares approach. The best-fit is obtained with a source at 4.6km depth beneath thewestern flank of the volcano and a volume variation of 3.6×10−4 km3/year. This result is in agreement with the volume rate retrieved by PS-InSAR technique and rather different from the rate inferred from leveling surveys. Consequently, non-linear trends of the hydrothermal system charge cannot be excluded apriori and the continuous GPS monitoring should be considered a priority in assessing the hazard of the Colli Albani.
    Description: This work has been partially supported by the Dept. of Civil Protection, Project DPC115 V3 Colli Albani.
    Description: Published
    Description: 79-87
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Colli Albani ; GPS ; Volcano monitoring ; Mogi source ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Present day kinematics of Italy (2012)
    Details
    Publication Date: 2017-04-03
    Description: We present the velocity field of Italy derived from the analysis of continuous GPS observations collected during 1998-2009 from 287 sites. The GPS networks analyzed cover the whole country with a mean inter-site distance of about 50 km. The processing is performed using two software programs, BERNESE and GAMIT, adopting in both cases a distributed session approach with more than 10 clusters, sharing common stations, each of them consisting of about 40 stations. Daily loosely constrained solutions (saved as SINEX files) are routinely produced for each cluster by two data analysis centres and the velocity field is obtained by stacking the daily normal equations. The rigorous combination of independent solutions allows the cross-validation of the velocity field. We have analyzed the time series of the entire area referenced to a common frame (ITRF2005 with respect to Eurasian Plate) and have estimated the velocity field providing an updated detailed picture of the kinematics (velocity map) and deformation pattern (strain rate map) of the Italian area. Additionally, we have combined the two velocity fields obtained from the two software programs obtaining the average velocity field of the Italian area. The two velocity fields agree at the level of 0.2-0.3 mm/yr consistent with their standard deviations. The deformation patterns (strain-rates) do have significant features, showing a distinctive extension along the Apennines on the order of 50-80 10-9 yr-1 and less pronounced areas of compressive tectonic behaviour at the level of 30-50 10-9 yr-1. The GPS kinematic description of the crustal deformation shows a high coherence with the seismotectonic setting of the Italian area.
    Description: This research has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) within the INGVDPC 2007-2009 agreement (project S1)
    Description: Published
    Description: paper 2
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: N/A or not JCR
    Description: restricted
    Keywords: Italian area ; GPS ; velocity field ; kinematics ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    Recent terrestrial and satellite observations to model deformations at Colli Albani volcano (central Italy) (2012)
    Springer Verlag New York Inc
    Details
    Publication Date: 2017-04-04
    Description: The Colli Albani volcanic complex (Rome, Italy) has been dominated by episodic eruptions commencing around 561 ka and ending with the most recent activity of the Albano maar phase (\70 ka). Earthquakes of moderate intensity, gas emissions and significant ground deformations are the recent evidences of a residual activity. Former geodetic data from leveling surveys, GPS stations and InSAR observations tracked ongoing significant uplift of the order of few mm/year near the Colli Albani western flank. Different uplift rates were detected by each technique in different time spans, suggesting also the possibility of sporadic recharge of the hydrothermal system. The renewed high precision leveling data from IGMI survey carried out in 1997/1999 and the last leveling survey carried out in 2006 show that the uplift along the route is currently significant at an average rate of *3 mm/year. Radar interferograms from ALOS satellite show uplift rate of *6 mm/year, southwest of the central sector of the leveling route. We have undertaken a joint inversion of the various geodetic data (vertical rates from leveling surveys, GPS site velocities and InSAR observations acquired by ALOS satellite) using a nonlinear inversion technique to estimate the parameters of a point-pressure source, possibly capable of explaining the ongoing deformation at Colli Albani volcano.
    Description: Published
    Description: 1661-1671
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Colli Albani ; GPS ; Leveling ; InSAR ; Volcano monitoring ; Mogi source ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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