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Riccardi, Umberto
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Riccardi, Umberto
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- PublicationRestrictedNon-isothermal momentum transfer and ground displacements rate at Campi Flegrei caldera (Southern Italy)We propose a thermo-fluid-dynamics model to study some recent uplift episodes occurred in the period 2008–2013 at Campi Flegrei caldera (Italy). Accounting for eight overpressure sources (from 5 to 40 MPa) in the hydrothermal system, our model solves for heat and momentum balances to obtain fluid velocities responsible for the observed ground displacement. For a validation of the model we use a dataset from seven continuous GNSS stations of the Neapolitan Volcanoes Continuous GPS network (NeVoCGPS), belonging to a geodetic monitoring system covering the Neapolitan volcanic area, and operated by the Istituto Nazionale di Geofisica e Vulcanologia. We compare the observed and modelled vertical displacements to assess “threshold” values for the vertical ground accelerations below which ground displacements could be described with the classic fluid-dynamics equations applied to the hydrothermal system without invoking a direct magmatic contribution. We find out that below 280 mm/yr2 the observed ground acceleration can be explained as just due to the interaction between the deep magmatic and hydrothermal systems. On the contrary, for values exceeding the modelled “threshold”, the direct magmatic contribution can be likely invoked as source of the ground deformations. Through this study, we target to contribute to the debate on the origin of the observed ground deformation, mainly to separate the effects of hydrothermal perturbations, caused by the injection of deep magmatic fluids into the aquifer, from the direct magma intrusion.
198 2 - PublicationRestrictedEvaluation of the atmospheric precipitable water at local scale during extreme weather using groundbased CGPS measurements(2013-09)
; ; ; ;Riccardi, U.; Università di Napoli Federico II ;Tammaro, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Capuano, P.; Università di Salerno; ; Global Positioning System (GPS) has demonstrated its ability to monitor the atmospheric water vapor content with an accuracy comparable to other techniques and means of measurements (e.g. radio soundings, microwave radiometers), even with good time resolution and under all meteorological conditions. The nowadays extensive use of permanent GPS stations, operating for geodetic purposes, offers a tool for a dense and reliable remote sensing of atmospheric water vapor. Here the tropospheric delay observed on some continuous GPS (CGPS) stations of the Italian GPS network (RING) is analyzed and its time evolution is discussed. We focus mainly on the study of the wet component of the atmospheric delay of the GPS signals and the computation of the precipitable water by using co-located GPS and meteorological stations. The results are described and discussed in comparison with different meteorological observations collected during extreme weather conditions impacting the Campania region.209 59 - PublicationRestrictedExploring deformation scenarios in Timanfaya volcanic area (Lanzarote, Canary Islands) from GNSS and ground based geodetic observationsWe report on a detailed geodetic continuous monitoring in Timanfaya volcanic area (TVA), where the most intense geothermal anomalies of Lanzarote Island are located. Weanalyze about three years of GNSS data collected on a small network of five permanent stations, one ofwhich at TVA, deployed on the island, and nearly 20 years of tiltmeter and strainmeter records acquired at Los Camelleros site settled in the facilities of the Geodynamics Laboratory of Lanzarote within TVA. This study is intended to contribute to understanding the active tectonics on Lanzarote Island and its origin, mainly in TVA. After characterizing and filtering out the seasonal periodicities related to “non-tectonic” sources from the geodetic records, a tentative ground deformation field is reconstructed through the analysis of both tilt, strain records and the time evolution of the baselines ranging the GNSS stations. The joint interpretation of the collected geodetic data showthat the area of the strongest geothermal anomaly in TVA is currently undergoing a SE trending relative displacement at a rate of about 3mm/year. This area even experiences a significant subsidence with a maximum rate of about 6 mm/year. Moreover, we examine the possible relation between the observed deformations and atmospheric effects bymodelling the response functions of temperature and rain recorded in the laboratory. Finally, fromthe retrieval of the deformation patterns and the joint analysis of geodetic and environmental observations, we propose a qualitative model of the interplaying role between the hydrological systems and the geothermal anomalies. Namely, we explain the detected time correlation between rainfall and ground deformation because of the enhancement of the thermal transfer fromthe underground heat sourcedriven by the infiltration of meteoric water.
201 5 - PublicationOpen AccessContinuous Gravity Observations at Mt. Somma-Vesuvius with a gPhoneX Gravimeter: In-Depth Instrumental Response Characterization and Tidal Model(2023)
; ; ; ; ; ; ;; ; ; ;We report on the results of about 9 months of gravimetric recordings acquired at Mt. Somma-Vesuvius (SV) volcano (Southern Italy) with the new generation relative gravimeter gPhoneX#116 (gPh#116), which is a gravimeter specifically designed for continuous gravity recording. We also present the outcomes of an intercomparison experiment of the gPhone#116 conducted at the J9 gravity observatory in Strasbourg (France). In this intercomparison, we were able to check the scale factor of the meter with a high degree of precision by means of an intercomparison with 2 superconducting gravimeters (SGs) and a FG5-type absolute ballistic gravimeter. Multiple calibration approaches allowed us to validate the manufacturer's original calibration constants to a level of 1% accuracy and 0.1% precision. Moreover, we carried out a comparative study of the noise level of the gPh#116 with respect to the SGs and other spring meters routinely used in both prospecting and time-lapse gravimetry. It turns out that gPh#116 exhibits lower levels at hourly time-scales than other compared spring gravimeters (Graviton, gPhone#054, Scintrex-CG5). It was also possible to carry out a detailed study of the instrumental drift, a crucial topic for reliable monitoring of the long-term gravity variations in active volcanic areas. In fact, a challenge in time-lapse gravimetry is the proper separation of the instrumental variations from real gravity changes eventually attributable to recharge or drainage processes of magma or fluids in the feeding systems of active volcanoes. A negative finding coming out from the intercomparison is that, even when applying the tilt correction, the gravimetric residuals obtained with the gPh#116 are an order of magnitude larger and quite inconsistent with those obtained with co-located superconducting gravimeters. We guess this problem could be overcome by installing the gravimeter on an auto-levelling platform. From the analysis of the gravity records, a reliable tidal gravity model was derived, which we believe will help to improve the accuracy of volcano monitoring, as it will allow appropriate correction of tidal effects for both relative and absolute gravity measurements acquired in the area. Two further interesting elements arose from our study: (1) a peculiar cavity effect of the SV underground laboratory that seems to influence the tilt change; (2) the small residual gravity signals are time correlated with the rainfall peaks and are compatible with gravity decreases induced by increases in soil moisture above the gravimeter.57 9 - PublicationOpen AccessContinuous record of the gravity changes at Mt. Vesuvius(1997-10)
; ; ; ; ;Berrino, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Corrado, G,; Dipartimento di Geofisica e Vulcanologia, Università di Napoli «Federico II», Napoli, Italy ;Magliulo, R.; Dipartimento di Geofisica e Vulcanologia, Università di Napoli «Federico II», Napoli, Italy ;Riccardi, U.; Dipartimento di Geofisica e Vulcanologia, Università di Napoli «Federico II», Napoli, Italy; ; ; High precision relative and absolute gravity measurements are periodically carried out at Mt. Vesuvius (Southern Italy) to monitor the changes in the gravity field caused by the internal dynamics of the volcano. Moreover, a recording gravity station is also operating at the Osservatorio Vesuviano (Old Building) aimed at measuring in continuous mode the time variations of the gravity and the tidal parameters, possibly due to changes in the physical state of the volcano. The analysis carried out on an hourly data set spanning the 1994-1996 time interval and a comparison of the results with those previously obtained, exhibit a change in the tidal parameters which occurred between 1991 and 1994. A gravity decrease of about 60 µGal was observed during the same time interval in the same area. Consistent with relative and absolute gravity observations, no significant variations have been detected since 1994 in the tidal parameters and gravity residuals.196 322 - PublicationOpen AccessTopography and structural heterogeneities in surface ground deformation: a simulation test for Somma-Vesuvius volcano(2021-03-19)
; ; ; ; ; ; ; ; ; We simulate the deformation of Somma-Vesuvius volcano due to some overpressure sources by means of a finite element 3D code. The main goal of these simulations is to investigate the influence of topography and structural heterogeneity on ground deformation. In our model the sources of deformation are embedded in an elastic linear isotropic medium and located at various depths. Geometry (shape and lateral extension) of the sources is mainly constrained by the results coming from recent seismic tomography studies. The structural heterogeneity has been modelled in terms of dynamic elastic parameters (Young’s modulus) retrieved from previous seismic tomography and gravity studies. A highresolution digital terrain model is used for the topography of the volcano subaerial edifice. Evidences from our results suggest that real topography and structural heterogeneities are key factors governing the ground deformation, which often turns being one of the most relevant problems in volcano monitoring. A large deviation from the axially symmetrical model of the displacement field is the main result of our modelling. Such an asymmetry is routinely unaccounted for when Mogi’s simplistic modelling in a homogeneous medium with simplified topography is used. Our study clearly demonstrate that a better knowledge of deformation patterns can significantly help in the location of monitoring sensors as well as in the design of an efficient geodetic network.117 8 - PublicationOpen AccessGravity tide in the Neapolitan volcanic area(2009-10)
; ; ; ; ; ;Riccardi, U.; Dipartimento di Scienze della Terra, Università “Federico II” di Napoli ;Berrino, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Corrado, G.; Dipartimento di Scienze della Terra, Università “Federico II” di Napoli ;Albano, A.; Dipartimento di Scienze della Terra, Università “Federico II” di Napoli ;Esposito, T.; Dipartimento di Scienze della Terra, Università “Federico II” di Napoli; ; ; ; Recording gravity stations are operating in the Neapolitan volcanic areas aimed at the geophysical monitoring of the volcanic activity. The availability of reliable models of the gravity tide in a volcanic area is the main condition to extract from the gravity records the signal possibly associated to volcanic sources...140 129 - PublicationOpen AccessNeapolitan volcanic area Tide Gauge Network (Southern Italy): Ground Displacements and Sea-Level Oscillations(2021-02-02)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In this study, we investigate the oscillations of relative sea level through the analysis of tide gauge records about 10-year long collected in the Gulfs of Pozzuoli and Napoli (Southern Italy). The main goal of this study is to provide a suitable resolution model of the sea tides including low frequency (seiches), tidal bands and non-linear tides. The spectral analyses of the tide gauge records lead us to identify a number of seiche periods some of them already known from the literature and some other unknown. Furthermore, we target a non-conventional purpose of the tidal analysis, namely extracting from the tide gauge records the volcanotectonic signal (vertical ground displacement) in the resurgent Campi Flegrei caldera. We suggest a method to filter out the volcano-tectonic signal (bradyseism) from the tide gauge records by deconvolving it from two records, one collected in the active volcanic area (Pozzuoli) and the other one collected in a tectonically stable station (Napoli), located beyond the caldera rim. Finally, we retrieve the relative mean sea level change in the Gulf of Naples and compare it with the trend found in five tide gauges spread along the Italian coast.291 8 - PublicationRestrictedAtmospheric Precipitable Water in Somma-Vesuvius Area During Extreme Weather Events from Ground-Based GPS Measurements(Springer, 2016)
; ; ; ; ; ; ; ; ; In this paper, we analyze the tropospheric delay observed on some ground-based CGPS stations in a dense small regional network and its time evolution during extreme weather conditions. In particular, we studied two severe weather events occurring in the Campanian Region (Italy) on October 12, 2012 and December 2, 2014, reaching 42 and 28 mm rainfall during about 1 h at Naples (MAFE) and Gragnano (GRAG) stations respectively. The main concern of this study is the retrieval of the precipitable water (PW) from co-located GPS and meteorological stations. We investigate the correlation between PW and rain amount at ground level. We analyse phase residuals for each visible GPS satellite using sky plots of the phase residuals along the GPS satellites tracks, showing that the two phenomena are shown in the phase residual plots. Moreover, we compare PWdata retrieved from observed meteorological data and from models (GPT2 and ECMWF), evidencing that there is a need for co-located CGPS and weather stations to improve the assessment of water content in the troposphere.100 9 - PublicationRestrictedNon-geodetic” approaches in the analysis of terrestrial CDGPS data for the retrieval of the atmospheric precipitable water at local scale during severe weather phenomena(2014-09)
; ; ; ; ; ;Tammaro, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Riccardi, U.; Università di Napoli Federico II ;Sorrentino, V.; Università di Salerno ;Forte, I.; Università di Salerno ;Capuano, P.; Università di Salerno; ; ; ; Precipitable water (PW) derived from the CDGPS (Continuous Differential Global Positioning System) zenith tropospheric delay (ZTD) is evaluated through comparison of three procedures: using GPT (Global Pressure and Temperature) and GPT2 global models as well as observed data. The results show that the difference between PW retrieved from models (GPT and GPT2) and PW obtained by observed meteorological data, at least for sites and period observed in this paper, is also a function of the position of the station. The short period considered does not allow for any consideration of possible intra-annual or annual periodicity. The analysis of the residuals between observed PW and modeled PW shows a peak before the rain event.155 18