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Di Maio, Rosa
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Di Maio, Rosa
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- PublicationOpen AccessGeophysical study of the hydrothermal reservoir in the Panza area (Ischia, Italy)(2007-04-15)
; ; ; ; ; ; ; ;Aiuppa, Alessandro ;Cosentino, Pietro ;D'Alessandro, Antonino; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Di Maio, R. ;Luzio, Dario ;Martorana, Raffaele ;Messina, Nicola ; ;; ; ; ;The aim of the present work is the reconstruction of the main geometric pattern and the characterisation with geophysical parameters of geological structures lying at small and medium depths in an area of the Ischia island (Italy), where a sensible hydrothermal activity is present.198 85 - PublicationOpen AccessApplication of electric and electromagnetic methods to the definition of the Campi Flegrei caldera (Italy)(2000-04)
; ; ; ; ; ; ;Di Maio, R.; Dipartimento di Scienze Fisiche, Università «Federico II», Napoli, Italy ;Patella, D.; Dipartimento di Scienze Fisiche, Università «Federico II», Napoli, Italy ;Petrillo, Z.; Osservatorio Vesuviano, Ercolano, Napoli, Italy ;Siniscalchi, A.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Cecere, G.; Dipartimento di Scienze Fisiche, Università «Federico II», Napoli, Italy ;De Martino, P.; Osservatorio Vesuviano, Ercolano, Napoli, Italy; ; ; ; ; The results of an analysis of Dipolar Geoelectrical (DG), Magnetotelluric (MT) and Self-Potential (SP) data collected over the emerged portion of the Campi Flegrei (CF) caldera (South Italy) are presented. The DG and MT data are from previous surveys, while the SP data have been recently collected during a survey consisting of 265 pickup land sites. Although the emerged part of the CF caldera appears as a highly inhomogeneous structure, a few simple features have been highlighted through an integrated analysis of subsets of consistent data. A well resolved feature is the structural pattern of the caldera depression along a roughly E-W profile, deduced from a 2D combined interpretation of the MT and DG soundings. Resistivity dispersion effects have also been observed at both ends of this profile. They have been ascribed to the presence of hydrothermally altered zones related to the main fracture systems bordering the caldera. A pressure/temperature source body at a mean depth of about 5 km bsl under the Bay of Pozzuoli has been inferred from the analysis of the 3D SP tomography imaging.302 568 - PublicationOpen AccessSelf-potential anomalies in some Italian volcanic areas(1996-01)
; ; ; ; ; ; ;Di Maio, R.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy ;Di Sevo, V.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy ;Giammetti, S.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy ;Patella, D.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy ;Piscitelli, S.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy ;Silenziario, C.; Dipartimento di Geofisica e Vulcanologia, Università «Federico II», Napoli, Italy; ; ; ; ; The study of Self-Potential (SP) space and time variations in volcanic areas may provide useful information on both the geometrical structure of the volcanic apparatuses and the dynamical behaviour of the feeding and uprising systems. In this paper, the results obtained on the islands of Vulcano (Eolian arc) and Ponza (Pontine archipelago) and on the Mt. Somma-Vesuvius complex are shown. On the island of Vulcano and on the Mt. Somma-Vesuvius apparatus areal SP surveys were performed with the aim of evidencing anomalies closely associated to the zones of major volcanic activity. On the island of Vulcano a profile across the fumaroles along the crater rim of the Fossa Cone was also carried out in order to have a direct relationship between fumarolic fracture migration and flow rate and SP anomaly space and time variations. The areal survey on the island of Ponza, which is considered an inactive area, is assumed as a reference test with which to compare the amplitude and pattern of the anomalies in the active areas. A tentative interpretation of the SP anomalies in volcanic areas is suggested in terms of electrokinetic phenomena, related to the movement of fluids of both volcanic and non-volcanic origin.201 10641 - PublicationOpen AccessJoint analysis of electric and gravimetric data for volcano monitoring. Application to data acquired at Vulcano Island (southern Italy) from 1993 to 1996Understanding the dynamics of volcanic-hydrothermal systems is a key factor for discriminating between magmatic and hydrothermal nature of the sources responsible for the unrest phenomena observed in active volcanic areas. Numerous studies of geophysical data monitoring in volcano-geothermal districts has indeed proven that close relationships exist between the volcanic and hydrothermal fluid circulation and the anomalous geophysical signals observed at the ground surface. In this paper, a simultaneous analysis that integrates resistivity and gravity data is suggested as a useful tool to infer a consistent conceptual model of hydrothermal volcanic systems and their evolution. An application of the proposed analysis to repeated resistivity and gravity measurements performed on Vulcano Island (Aeolian Archipelago, Sicily, southern Italy) is presentedwith the aimof gaining information on the dynamics of the volcanic-hydrothermal system. The examined period ranges fromDecember 1993 to September 1996,when significant changes in chemical properties, temperatures and emission rates of La Fossa crater fumaroles were observed, all indicating an increase in the flux of hot deep magmatic gases. The results of our analysis, which refers to a profile located at the foot of the northwest flank of La Fossa cone, suggest that underground cyclicwater-to-vapour transformations govern the shallowhydrothermal systemdynamics, generally described by a negative correlation between the monitored resistivity and gravity data. The occurrence of positive correlations between the two analysed parameters could be ascribed to volcanic dynamics, which would mask the normal hydrological and hydrothermal system behaviour.
137 45 - PublicationOpen AccessStatistical moments of power spectrum: a fast tool for the classification of seismic events recorded on volcanoes(2020)
; ; ; ; ; ; ; ; ; ; ; Spectral analysis has been applied to almost thou-sand seismic events recorded at Vesuvius volcano (Naples,southern Italy) in 2018 with the aim to test a new tool fora fast event classification. We computed two spectral pa-rameters, central frequency and shape factor, from the spec-tral moments of order 0, 1, and 2, for each event at sevenseismic stations taking the mean among the three compo-nents of ground motion. The analyzed events consist ofvolcano-tectonic earthquakes, low frequency events and un-classified events (landslides, rockfall, thunders, quarry blasts,etc.). Most of them are of low magnitude, and/or low maxi-mum signal amplitude, therefore the signal to noise ratio isvery different between the low noise summit stations andthe higher noise stations installed at low elevation aroundthe volcano. The results of our analysis show that volcano-tectonic earthquakes and low frequency events are easily dis-tinguishable through the spectral moments values, particu-larly at seismic stations closer to the epicenter. On the con-trary, unclassified events show the spectral parameters valuesdistributed in a broad range which overlap both the volcano-tectonic earthquakes and the low frequency events. Since thecomputation of spectral parameters is extremely easy and fastfor a detected event, it may become an effective tool for eventclassification in observatory practice.422 18 - PublicationOpen AccessCaratterizzazione geofisica dell'acquifero idrotermale dell'area di Panza (Ischia)(2007-11-13)
; ; ; ; ; ; ; ; ; ; ;Aiuppa, Alessandro ;Cosentino, Pietro ;D'Alessandro, Antonino; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Di Maio, R. ;Fiandaca, G. ;Luzio, Dario ;Martorana, Raffaele ;Messina, Nicola ;Roberti, N. ;Soldovieri, M.G. ; ;; ; ; ; ; ; ;Gli obiettivi di questo lavoro sono quelli di ricostruire, con metodologie geofisiche integrate, le principali geometrie tettoniche ed idrogeologiche del territorio di Panza nell’isola di Ischia. La zona è stata scelta in quanto caratterizzata da un’intensa attività idrotermale e deformativa connessa con la presenza di un reservoir geotermico.210 377 - PublicationOpen AccessModelling earth current precursors in earthquake prediction(1997-03)
; ; ; ;Patella, D.; Dipartimento di Geofisica e Vulcanologia, Università di Napoli «Federico II», Napoli, Italy ;Tramacere, A.; Dipartimento di Geologia e Geofisica, Università di Bari, Italy ;Di Maio, R.; Dipartimento di Geofisica e Vulcanologia, Università di Napoli «Federico II», Napoli, Italy; ; This paper deals with the theory of earth current precursors of earthquake. A dilatancy-diffusion-polarization model is proposed to explain the anomalies of the electric potential, which are observed on the ground surface prior to some earthquakes. The electric polarization is believed to be the electrokinetic effect due to the invasion of fluids into new pores, which are opened inside a stressed-dilated rock body. The time and space variation of the distribution of the electric potential in a layered earth as well as in a faulted half-space is studied in detail. It results that the surface response depends on the underground conductivity distribution and on the relative disposition of the measuring dipole with respect to the buried bipole source. A field procedure based on the use of an areal layout of the recording sites is proposed, in order to obtain the most complete information on the time and space evolution of the precursory phenomena in any given seismic region.188 377 - PublicationRestrictedThe 847 CE earthquake in central-southern Italy: New hints from archaeosismological and geophysical investigations in the Volturno River Valley area(2020-01-05)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Integration of archaeoseismic observations, geological and geophysical surveys and a critical review of historical written sources contributed to shed light on the effects of the 847 earthquake AD that struck a large area of Southern-Central Italy. New archaeoseismic evidence of a strong earthquake comes from two Medieval archaeological sites along the Volturno Valley, between Campania and Molise regions, which occurred around the middle of the ninth century AD. Evidence includes the tilting of pillars in the Basilica of Santa Maria near Alvignano (northern Campania) and a collapsed masonry wall in the Abbey of San Vincenzo al Volturno near Isernia (northern Molise). At Alvignano, a site so far unrecorded in seismic catalogues for the 847 earthquake, geoelectrical and georadar investigations were used to explore the subsoil and study local site conditions, which could have influenced coseismic ground motion. Integrated interpretation of geophysical surveys and borehole logs document the presence of altered pyroclastic deposits, which certainly enhanced site effects at Alvignano. Analysis of damage descriptions and of archaeological reports indicate that the 847 seismic event documented by historical sources damaged a wide area between Latium, Campania and Molise, with destruction of the town of Isernia. Although historical sources did not explicitly mention damage in Rome, seismic effects attributed to the 847 event are recorded in the archaeological and seismological literature. Because the damaged area for this medieval earthquake is loosely defined due to the scanty documentation, the present study represents an important contribution to better define the shaking area and provide new hints on the extent and location of the possible seismogenic source.347 2 - PublicationRestrictedShear wave velocity and attenuation structure of Ischia island using broad band seismic noise records(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; In volcanic areas, accurate localization of earthquakes requires detailed velocity and, possibly, attenuation models, taking into account wide lithological variability and high geothermal gradients. Ischia island (Campania region, Italy) is a seismically-active volcano recently affected by a Mw 3.9 event (Casamicciola, August 21, 2017, 1 km depth). Due to the lack of a specific velocity model, the earthquakes occurred on the island were localized using the one developed for the nearby Campi Flegrei caldera. The aim of this work is the definition of a mean representative 1D shear-wave velocity (Vs) and attenuation (Q) model of the shallower crust (up to 2 km depth) of Ischia. Seismic noise array and spectral ratios techniques were applied to broad band seismic signals recorded by temporary and permanent networks updated after the August 2017 earthquake. The values of both shear-wave velocity (Vs) and quality factor (Q) are realistic, with Q values comparable with those obtained for Campi Flegrei and Stromboli volcanic areas. By taking into account stratigraphic information from deep wells and ultrasonic measurements of velocity on granite and trachytic lava samples, a geological interpretation of the resulting velocity model is provided. Such a model can have significant implications for understanding the dynamics of a volcano, mainly those leading to seismic activity.651 15 - PublicationOpen AccessSource analysis of low frequency seismicity at Mt. Vesuvius by a hybrid moment tensor inversionSeismicity at Mt. Vesuvius has been relatively weak in the last decades. While the occurrence of shallow volcanotectonic (VT) events at Mt. Vesuvius is well known, the occurrence of deeper low frequency events (LF) was only recently recognized. Previous source studies only targeted VT events, which were found to have quite heterogeneous focal mechanisms. In this paper, we perform for the first time the source inversion of LF seismicity at Mt. Vesuvius, analysing 27 LF events recorded from 2012 to 2021 with the aim to investigate their source processes. Given the challenges of analysing weak LF earthquakes, we implement a specific moment tensor (MT) inversion approach that combines the fit of displacement seismograms in the time domain and amplitude spectra in the frequency domain. The inversion is simultaneously performed for the source depth and moment tensor components in the 2–7 and 2–5 Hz frequency band, assuming either a full or deviatoric MT representation. Source parameter uncertainties are estimated by using a Bayesian bootstrapping scheme. Our results confirm a larger depth of LF events compared to VTs and show a strong heterogeneity of the LF seismic sources, which present various rupture types, different orientations and heterogeneous, whilst poorly resolved, non-double-couple components. The MT variability is qualitatively confirmed by significant differences among the recorded waveforms. The heterogeneity of both VT and LF source processes is attributed to complex source processes in a highly fractured seismogenic volume submitted to a heterogeneous stress field
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