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Riguzzi, Federica
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Riguzzi, Federica
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federica.riguzzi@ingv.it
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120 results
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- PublicationOpen AccessThe absolute gravity network of Italy in the framework of the ITGRS/ITGRF(2024-09-04)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The activities for establishing the Italian Reference Gravity Network started in 2022. This is in line with the actions promoted by the International Association of Geodesy that during its 2015 General Assembly approved a resolution on the establishment of the new global gravity network the so-called International Terrestrial Gravity Reference System/Frame that will replace IGSN71. An initial set of 30 stations has been defined over the peninsular part of Italy and the two main islands of Sicily and Sardinia. Particularly, the GGOS core station of Matera (the Agenzia Spaziale Italiana Center for Space Geodesy “Bepi” Colombo) is one of the network points as required in the documents of the GGOS-Bureau of Networks and Observations. Thus, this station will provide one link between the Italian national absolute gravity network and the GGOS observation system of IAG. In order to ensure the measurements traceability, as required by the international standards on gravity measurements, the absolute gravimeters used in the measurements participated in international comparison campaigns. Absolute gravity measurements have been supplemented with direct measurements of the local value of the vertical gravity gradient, in order to reduce the absolute values, measured by different instruments at different heights, to an intermediate and common reference height and to the ground reference level to transport it to an external associated station. The gravity field campaigns have been assisted by topographic survey campaigns, allowing a centimetric georeferencing of the gravity stations to the current ITRF. The collected data will be then validated and reduced following the internationally accepted standards and finally published through a dedicate web page of the project. These data will also be submitted to the absolute gravity database maintained by the Bureau Gravimétrique International/Bundesamt fuer Kartographie und Geodaesie where the absolute gravity data that will contribute to the new global absolute gravity reference system are collected.39 16 - PublicationOpen Access
58 80 - PublicationEmbargoHydrology Drives Crustal Deformation and Modulates Seismicity in the Matese Massif (Italy)(2024)
; ; ; ; ; We analyze the interplay between hydrology, deformation and seismicity in the Matese massif, located in the Italian Southern Apennines. We find that this area is characterized by the concurrent action of two hydrologically-driven processes: the first is the deformation detected by GNSS data in the shallowest part (above the elevation of the major springs) of the Earth crust, in phase with the hydrological forcing; the second is the triggering of seismicity at depth with a delay suggesting a downward diffusive process. We study the first process by applying a Principal Component Analysis to the GNSS displacements time series, aiming to identify a common signal describing the largest data variance. We find that the maximum horizontal displacements associated with the first principal component (PC1) are larger than 1 cm in two GNSS sites and the PC1 temporal evolution is well correlated and in phase with the flow of the largest spring of the region, which we consider as proxy of the water content of the massif. This suggests that the main source of horizontal deformation is the water content fluctuations in the shallow portion of the Matese aquifer, in particular within fractures located in correspondence of the main mapped faults. The deformation rates caused by this process are one order of magnitude larger than the tectonic ones. Finally, we infer the second process by observing the correlation between the background seismicity and the spring discharge with a time lag of 121 days. In our interpretation, downward diffusive processes, driven by aquifer water content variations, propagate pore pressure waves that affect the faults strength favoring the occurrence of micro-earthquakes. This is supported by the values of hydraulic diffusivity (1.5 m^2/s) and rock permeability (3.2-3.8⋅10^−13 m^2), which are compatible with what is observed in karstified limestones.53 59 - PublicationOpen AccessAbsolute gravity and deformation measurements for a multi-disciplinary study in Central Italy(2023-02-07)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Since 2018, INGV funded 3 projects aimed to detect ground deformations and gravity variations over different timescale in the area where the recent seismic events of L’Aquila (2009, Mw 6.3) and Amatrice-Norcia (2016, Mw 6.1 and 6.5) took place. The consequent static deformation field reached several centimetres and the modelled impact of such events could have modified the gravity field up to 170 μGal. Furthermore, the medium-long-term gravity and ground deformation variations related to post-seismic relaxation are expected as consequence of vertical deformation of the Earth surface and/or of the internal boundaries separating layers at depth with different densities. In addition, the L’Aquila area is affected by deformations induced by ground water level changes in the aquifers. Therefore, a multidisciplinary approach carrying out joint measurements of deformation and gravity is fundamental to understand the role of each geophysical process. To this aim, a network of 3 (Terni, Popoli, Sant’Angelo Romano) new non-permanent GNSS stations was realized outside the buildings hosting the absolute gravity stations. At L’Aquila, a permanent GNSS station managed by the Italian Space Agency (AQUI) is continuously working on the rooftop terrace of the Science Faculty, and positioned vertically with respect to the gravimetric station (AQUIg), which is located 4 floors below. Since 4 absolute gravimetric sites are located indoor, the precise coordinates of the gravity benchmark have been obtained by classical topographic surveys, connecting the indoor site to the outdoor GNSS reference point. Here we present the gravity and ground deformation variations observed in the period 2018-2022 after five measurement campaigns.65 43 - PublicationOpen AccessThe first absolute gravity and height reference network in Sicily(2023-02-07)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In this poster we present the realization and the surveys performed to establish a new reference gravity and elevation network in Sicily with the aim to provide new reference systems useful for all the scientific and technological activities related to the gravity field and to the proper definition of a modern height system in this region. This network belongs to the under construction new Italian Reference Gravity Network (G0) that is part of the INGV Project Pianeta Dinamico, Task S2, during the period 2019-2022. The Sicilian network encloses 5 stations (Catania, Centuripe, Milazzo, Noto, and Palermo), evenly distributed forming a large mesh network which roughly covers the entire Sicily (Fig.1). All absolute stations are hosted inside structures that guarantee protection for the instrumentation during the measurements and the necessary power supply. In addition to the absolute gravity value, at each station, the vertical gravity gradient and the gravity difference (Δg) between the indoor absolute gravity and an outdoor satellite station were also measured. Gravity measurements were carried out between the end of 2021 and the 2022 with the Microg LaCoste FG5#238 and the Scintrex CG-6 gravimeters for absolute and relative measurements, respectively. Gravity data have been corrected for known effects ensuring the reliability and accuracy at the µGal level. The coordinates and the orthometric heights were at the same time measured with mixed terrestrial and satellite local networks at each site. The precise coordinates obtained after the adjustments were useful to post-process the absolute gravity data and to refer all the gravity measurements presented in this work to the equipotential surface of the gravity field. Since three of the five selected stations were measured in the past, it was also possible to evaluate the long-term stability of the gravity values at these stations.100 93 - PublicationOpen AccessGNSS and absolute gravity measurements for a multi-disciplinary study of natural risks in Central Italy(2022-09-19)
; ; ; ; ; ; ; ; ; ; ; ; ; Crustal deformations are widely studied in Italy by analyzing data from GNSS permanent networks. However, deformations can be generated by very different geophysical processes related to tectonics but also to fluid circulation and density variations. Therefore, it is very important to understand if the detected deformations are connected to gravity variations (Greco et al., 2021a). Since 2018, INGV funded 3 projects aimed to detect ground deformations and gravity variations over different timescale in the area where the recent seismic events of L’Aquila (2009, Mw 6.3) and Amatrice-Norcia (2016, Mw 6.1 and 6.5) took place. The consequent static deformation field reached several centimetres and the modelled impact of such events could have modified the gravity field up to 170 μGal (Riguzzi et al., 2019). Furthermore, the medium-long-term gravity and ground deformation variations related to post-seismic relaxation are expected as consequence of vertical deformation of the Earth surface and/or of the internal boundaries separating layers at depth with different densities. In addition, the L’Aquila area is affected by deformations induced by ground water level changes in the aquifers (Devoti et al., 2018). Therefore, a multidisciplinary approach carrying out joint measurements of deformation and gravity is fundamental to understand the role of each geophysical process. To this aim, a network of 3 (Terni, Popoli, Sant’Angelo Romano) new non-permanent GNSS stations was realized outside the buildings hosting the absolute gravity stations (Greco et al., 2021b). At L’Aquila, a permanent GNSS station managed by the Italian Space Agency (AQUI) is continuously working on the rooftop terrace of the Science Faculty, and positioned vertically with respect to the gravimetric station (AQUIg), which is located 4 floors below (Fortunato et al., 2020). Since 4 absolute gravimetric sites are located indoor, the precise coordinates of the gravity benchmark have been obtained by classical topographic surveys, connecting the indoor site to the outdoor GNSS reference point. In the poster we describe the procedure and results followed to achieve the coordinates of both the GNSS and the absolute gravimetric sites. Furthermore, we also present the results over the short and the medium-long-term obtained by repetitive combined GNSS and integrated absolute and relative gravity measurements.73 46 - PublicationOpen AccessInsights into Seismogenetic Areas in Central Italy from Combined Absolute Gravity and GNSS Measurements(2021-11-18)
; ; ; ; ; In this study we present and discuss gravity and ground deformation variations, at different time scales, observed in a wide mesh absolute gravity and GNSS network set up in central Italy. The network was installed in the area affected by the 2009 (L’Aquila; Mw 6.1) and 2016 (Amatrice-Norcia; Mw 6.0 and 6.5) seismic activity, in order to verify if gravity and ground deformation variations could be related to seismic effects. The new network includes 5 stations distributed between the Lazio, Umbria, and Abruzzo regions. From 2018 to 2020 three campaigns were carried out using the transportable Micro-g LaCoste FG5#238 and the portable Micro-g LaCoste A10#39 absolute gravimeters and completed with two simultaneous GNSS measurements. Topographic instruments, measurement and analysis techniques enabling accurate measurements in the positioning of the stations and to control their variations over time were applied. The high reliability and accuracy of the absolute gravity data gathered, after being corrected for known effects, showed a negative short-term (2018–2020) pattern throughout the area, up to +30 microGal. Since some stations of the new network coincided with benchmarks already measured in the past, an analysis of long-term gravity changes was carried out and a fair degree of stability was observed in two stations, while positive large variations, of approximately 70 and 157 microGal, were recorded in the other two stations in the time intervals 1954–2020 and 2005–2010, respectively. On the other hand, variations highlighted by GNSS height measurements were all below 3 cm. Here, the first long-lasting gravity measurements carried out with absolute gravimeters in a seismic area in Italy are presented, providing meaningful geophysical information. The obtained results, in terms of availability of a combined absolute gravity and GNSS network, definition of data acquisition and analysis procedures, as well as creation of a high quality data archive, lay the foundations for a multidisciplinary approach towards improving the knowledge of this seismogenetic area of Italy.374 25 - PublicationOpen AccessGNSS data provide unexpected insights in hydrogeologic processes(2021)
; ; ; ; ; The analysis of long time series of Global Navigation Satellite System (GNSS) observations has recently evidenced that the slow tectonic processes are not the only ones producing the observed slow deformations, but the Earth’s crust reacts also to stresses induced by pressure variations and water circulation. The basic mechanisms are substantially of two kinds: deformations induced by the elastic response of the loaded surface and deformations due to the poroelastic properties of the ground. These mechanisms are quite different, in the first case the water load causes subsidence, in the second uplift; both create horizontal deformations moving away from the centre of deformation. Under anisotropic conditions, water pressure changes in poroelastic soils can induce large horizontal deformations especially where highly fractured rocks may provide permeability for fluid flow. Both elastic and poroelastic phenomena are observable and measurable by continuous GNSS monitoring of ground deformations. Both can be triggered by periodical atmospheric processes but also by extreme events, like heavy rainfalls. We will show a few case studies, observed in the Italian area, that demonstrate how the deformation patterns, at different repeating periods, clearly correlate with groundwater circulation in different environmental condition.276 87 - PublicationOpen AccessThe first combined absolute gravity and GNSS network in Central Italy(2021)
; ; ; ; ; ; ; ; ; ; ; A first combined absolute gravity and GNSS network of 5 stations distributed between Lazio, Umbria and Abruzzo regions, was realized in 2018 in order to lay the basics for a multidisciplinary approach to natural risk assessment in the area of Central Italy, affected by the 2009 and 2016 seismic activity. Up to now, two absolute gravity campaigns were carried out using the transportable Microg LaCoste FG5#238 and the portable A10#39 absolute gravimeters. The locations of gravimetric sites have been chosen indoor to allow optimal condition of measure; therefore, the heights of the indoor sites have been determined by joining the outdoor GNSS with classical topographic surveys. The good results obtained after the campaigns and data processing lay the foundations for a new multidisciplinary approach to study also seismogenetic areas. In this paper, we present the gravity and GNSS station monographs, together with the absolute gravity values and the coordinates resulting from the first field surveys.497 106 - PublicationOpen AccessGeopositioning time series from offshore platforms in the Adriatic Sea(2020-11-04)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We provide a dataset of 3D coordinate time series of 37 continuous GNSS stations installed for stability monitoring purposes on onshore and offshore industrial settlements along a NW-SE-oriented and ~100-km-wide belt encompassing the eastern Italian coast and the Adriatic Sea. The dataset results from the analysis performed by using different geodetic software (Bernese, GAMIT/GLOBK and GIPSY) and consists of six raw position time series solutions, referred to IGb08 and IGS14 reference frames. Time series analyses and comparisons evidence that the different solutions are consistent between them, despite the use of different software, models, strategy processing and frame realizations. We observe that the offshore stations are subject to significant seasonal oscillations probably due to seasonal environmental loads, seasonal temperature-induced platform deformation and hydrostatic pressure variations. Many stations are characterized by non-linear time series, suggesting a complex interplay between regional (long-term tectonic stress) and local sources of deformation (e.g. reservoirs depletion, sediment compaction). Computed raw time series, logs files, phasor diagrams and time series comparison plots are distributed via PANGAEA ( https://www.pangaea.de ).1129 23