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Di Giuseppe, Maria Giulia
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Di Giuseppe, Maria Giulia
Email
mariagiulia.digiuseppe@ingv.it
Staff
staff
ORCID
Researcher ID
A-2421-2012
33 results
Now showing 1 - 10 of 33
- PublicationOpen AccessSeismically Induced Soft‐Sediment Deformation Phenomena During the Volcano‐Tectonic Activity of Campi Flegrei Caldera (Southern Italy) in the Last 15 kyr(2019-06)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We report, for the first time, evidence of seismically induced soft‐sediment deformations in the central area of the active Campi Flegrei caldera (southern Italy). We analyzed the marine‐transitional and continental sequences located along the coastal La Starza cliffs and several stratigraphic logs exposed during the excavation of a 1‐km‐long tunnel in the Pozzuoli area. The successions host several soft‐sediment structures including sand dikes and sand volcanoes, which are largely dated within the 4.55‐ to 4.28‐kyr BP interval. The volcano‐sedimentary sequence, deposited within the Campi Flegrei caldera in the last 15 kyr, is schematically formed by the superposition of three layers with different rheological behaviors; from the base progressing upward we recognize (1) a massive tuff, (2) marine‐transitional sands of the La Starza unit, and (3) a dominance of continental volcanoclastics. We envisage that during unrest episodes of the volcano, which included ground deformation and seismic activity, the whole volcano‐sedimentary pile was deformed through brittle mechanisms with the formation of normal faults. However, the intermediate layer, when subject to seismic shaking, behaved locally as a viscous material facilitating liquefaction processes and lateral spreading deformation. Furthermore, new geophysical, stratigraphic, and structural surveys allowed us to model the deformation evolution of this area over the last 15 kyr. The evidence of seismically induced soft‐sediment deformation within the volcano‐sedimentary record suggests that moderate earthquakes could occur during future volcano‐seismic unrests. Consequently, liquefaction and related gravitational mass movements must be considered as a hazard during these unrest and volcanic crises.90 55 - PublicationRestrictedFluid injection in Enhanced Geothermal Systems: a study on the detectability of self-potential effects and on their correlation with induced seismicity(2017)
; ; ; ; ; ; ; ; ; ; ; We present a numerical modeling aimed at investigating nature and role of the self-potential (SP) anoma- lies induced by water injection in boreholes at the Soultz-sous-Forêts (SsF) hot dry rock enhanced geothermal field. The overpressure due to the fluid stimulation is considered as source of the streaming potential effects in rocks, responsible on their turn of the SP anomalies observed at the ground surface. The numerical simulations have been realized by a combined application of the TOUGH2 and Comsol Mul- tiphysics codes, which had already been successfully used to predict Coulomb stress changes in rocks induced by a fluid injection cycle. Two synthetic cases are investigated. At first, a simulated injection cycle in a single borehole has been modeled, consisting in the reconstruction of the overpressure and SP temporal and spatial evolutions induced by the hydraulic stimulation of the rock. The main result is that the front of the SP anomaly follows the overpressure front, with the time delay between the two fronts decreasing at increasing distance from the well. The second case takes into consideration a real injection experiment performed in 2003 at SsF, which has allowed to examine the induced seismicity. The simulated SP response to this real injection cycle shows that the SP temporal evolution is essentially a post-seismic effect. The conclusion from the simulations is that SP measurements can be used to localize the main features of the fluid flow into the reservoir.246 27 - PublicationOpen AccessStratigraphy, structure, and volcano-tectonic evolution of Solfatara maar-diatreme (Campi Flegrei, Italy)(2015)
; ; ; ; ; ; ; ;; ; ;This study focuses on the Solfatara volcano within Campi Flegrei, a volcanic eld located on the Tyrrhenian coast of southern Italy. Volcanism at the Campi Flegrei caldera has included phreatic to phreatomagmatic explosions and both magmatic (ranging from small scoria-producing events to those with Plinian columns) and effusive eruptions. These eruptions have formed tuff cones, tuff rings, minor scoria cones, and lava domes. A detailed stratigraphic, structural, and geo- physical study of the area indicates that the Solfatara volcano is a maar-diatreme structure previously not recognized within the Campi Flegrei caldera. It is characterized by a crater cut into earlier volcanic deposits, a small rim of ejecta, and a deep structure (down to 2–3 km). This maar-diatreme has allowed the gases and uids to ow up to the surface over a long time. A new geological map and cross sections show a complex architecture of different volcano-tectonic features including scoria cones, lavas, crypto- domes, feeder dikes, pipes, ring and regional faults, and explosive craters. Volcanological data were collected with the main aim of characterizing the eruptive activity in a lim- ited sector of the caldera. Fault and fracture analyses, using the scan line methodology, highlight the role of the main structures that accompanied the volcanic evolution within this sector of the Campi Flegrei caldera. To better constrain the subsurface structure of the Solfatara crater, electrical resistivity tomography investigations were integrated with the volcano-tectonic information. All data suggest that the Solfatara area is dominated by a maar-diatreme evolution. Pres- ently, the Solfatara area shows widespread hydrothermal and fumarolic activity that is localized along the major faults. The results allow us to de ne a particular type of vol- canic activity in the recent past, in what is still considered today an area with a higher probability of opening new vents, particu- larly for possible phreatic activity.116 105 - PublicationOpen AccessVolcano‐Tectonic Setting of the Pisciarelli Fumarole Field, Campi Flegrei Caldera, Southern Italy: Insights Into Fluid Circulation Patterns and Hazard Scenarios(2021-04-21)
; ; ; ; ; ; ; ; ; ; ; Phreatic and hydrothermal eruptions are small energetic explosive events that generally have few to no precursors and represent a considerable hazard in tourist and urban areas. At the Campi Flegrei caldera, these events have occurred at the Solfatara volcano and have likely occurred at the nearby Pisciarelli site, where the most powerful hydrothermal phenomena are located. Here, increased hydrothermal activity has caused relevant morphological changes that has led local authorities to deny access to the site. Stratigraphic, structural, and geophysical investigations have allowed us to reconstruct the volcano-tectonic setting of the area. In particular, we have recognized a fault system and related damage zones that act as the preferred pathway for hydrothermal fluids in the caldera. At the surface, these faults control the migration and/or accumulation of deep-seated gases into the subsoil and the formation of fumaroles and mud pools. We have recognized two main fault systems with different ages that show variable displacements. The electrical anomalies identified by electrical resistivity tomography further highlight the main fault pattern and show the interplay between volcano-tectonic structures and fluid circulation. Host rocks and fault zones may be involved in self-sealing processes and/or rock failure phenomena capable of modifying the fluid pathways and establishing favorable conditions, leading to overpressure and/or rapid decompression of fluids and triggering an explosive event. Furthermore, stratigraphic mapping shows fossil mud pool sediments embedded in an old debris flow located above the modern hydrothermal system. This implies that they were at a higher elevation when they formed. The morphotectonic evolution and intense rock alterations in the area could promote further landslide episodes, producing debris-flow deposits that can cover the active area and possibly trigger hydrothermal/ phreatic events.81 100 - PublicationRestrictedGeothermal Investigations of Active Volcanoes: The Example of Ischia Island and Campi Flegrei Caldera (Southern Italy)(2015)
; ; ; ; ; ; ; ; ; ; ; The active volcanic zone of Ischia Island and Campi Flegrei caldera (Campania) have been the site of many geothermal investigations, since the early 20th century. These areas are characterized by very high geothermal gradient and heat flow as consequence of upward migration of magmatic sources coupled with vigorous hydrothermal circulation. After the increment of installed geothermal power in Larderello (Tuscany), the extensive geothermal exploration of Campania was not followed by exploitation projects. In recent time, the attention on the possibility to exploit electric energy has been drawn by the new Italian regulation for exploitation leases. The larger geothermal potential of Campi Flegrei caldera and Ischia Island, located west to the Bay of Naples, makes these areas as possible sites of new geothermal plants installation. We present here the results of recent geothermal researches of Campi Flegrei caldera and Ischia Island, which integrate and improve the information obtained during the exploration performed by SAFEN and AGIP-ENEL companies from the earlier 1940 to 1985. These data are useful to characterize the geothermal reservoirs of this active volcanoes and also to increase the knowledge of volcanic processes and related risk.120 9 - PublicationOpen AccessThe role of stress-dependent permeability in enhanced geothermal systems modelling(2014-07-02)
; ; ; ; ; ; ; We present a procedure for testing the interpretation of the induced seismicity. The procedure is based on Coulomb stress changes induced by deep fluid injection during well stimulation, providing a way to estimate how the potential for seismic failure in different volumes of a geothermal reservoir might change due to the water injection. It was successfully applied to reproduce the observations collected during and after the complex stimulation cycle of the GPK2 and GPK3 wells at the Soultz sous Foret Enhanced Geothermal System EGS site (Alsace, France). In this paper, a conceptual model that links the induced stress tensor and the permeability modifications is considered, with the aim to estimate the permeability change induced during the water injection. In this way, we can adapt the medium behaviour to mechanical changes, in order to better evaluate the effectiveness of the stimulation process for the enhancement of the reservoir permeability, while also refining the reconstruction of the Coulomb stress change patterns. Numerical tests have been developed that consider a physical medium comparable with the granitic basement of the Soultz EGS site, and a geometry of the system that is compatible with that of the GPK2-GPK3 wells. In such a way, the forecasting of the areas of higher likelihood for induced seismicity results in a good agreement between Coulomb stress change patterns and induced seismicity.89 37 - PublicationOpen AccessAbout the shallow resistivity structure of Vesuvius volcano(2008-02)
; ; ; ; ; ; ; ; ;Troiano, A.; Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy ;Petrillo, Z.; Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy ;Di Giuseppe, M. G.; Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy ;Balasco, M.; Istituto di Metodologie per l’Analisi Ambientale (IMAA, CNR), Tito Scalo (Pz), Italy ;Diaferia, I.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, Italy ;Di Fiore, B.; Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy ;Siniscalchi, A.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, Italy ;Patella, D.; Dipartimento di Fisica, Università degli Studi di Napoli «Federico II», Napoli, Italy; ; ; ; ; ; ; Magnetotelluric (MT) soundings performed in the past in the volcanic area of Mt. Vesuvius by two independent research groups showed in the same places MT apparent resistivity curves with very similar shape, but statically shifted by one order of magnitude, at least. To try to resolve this ambiguity new controlled source audio-magnetotelluric (CSAMT) measurements have been carried out in the same MT sites. The interpretation of the CSAMT dataset, combined with that of two shallow dipole-dipole geoelectrical resistivity tomographies previously carried out in the area have allowed a reliable electrical structure to be recovered down to a few km of depth, which will next be used for a best constrained re-interpretation of the deep MT soundings.449 746 - PublicationRestrictedThe geothermal system of Ischia Island (southern Italy): Critical review and sustainability analysis of geothermal resource for electricity generation(2014)
; ; ; ; ; ; ; ; ; ; ; In this paper we analyze the main available data related to the geothermal system of Ischia Island, starting from the first geothermal exploration in 1939. Our aim is to define a conceptual model of the geothermal reservoir, according to geological, geochemical, geophysical and stratigraphic data. In recent times, the interest on geothermal exploitation for electricity generation in Italy is rapidly increasing and the Ischia Island is one of the main targets for future geothermal exploitation. Nowadays, one of the main economic resources of the island is the tourism, mainly driven by the famous thermal springs; so, it is crucial to study the possible interaction between geothermal exploitation and thermal spring activities. To this aim, we also analyze the possible disturbance on temperature and pressure in the shallow geothermal reservoir, due to the heat withdrawal for electric production related to small power plant size (1e5 MWe). Such analysis has been performed by using numerical simulations based on a well known thermofluid-dynamical code (TOUGH2!). Obtained results show that such geothermal exploitation generates a perturbation of temperature and pressure field which, however, is confined in a small vol- ume around the well. At shallow level (0e100 m) the exploitation does not produce any appreciable disturbance, and can be made compatible with thermal spring exploitation. Moreover, such results are crucial both for the evaluation of volcanological processes in the island and for the general assessment of geothermal resource sustainability.300 5 - PublicationOpen AccessA geophysical k-means cluster analysis of the Solfatara-Pisciarelli volcano-geothermal system, Campi Flegrei (Naples, Italy)(2018)
; ; ; ; ; ; ; ;; We present an application of the k-means cluster analysis technique to a trivariate geophysical parameter set dis- tributed over a 3 km thick and 1.2 km long section through the geothermally active Solfatara-Pisciarelli area of the Campi Flegrei caldera (Italy). The data set consists of resistivity, P-wave velocity and density parameters, ex- tracted from previously modeled univariate sections through the selected profile and mapped in a joint param- eter 3D space. Six compact and separated clusters have been identified. A subsequent linear regression statistics has allowed two distinct branches of clusters to be recognized, each represented in the joint parameter space by the equation of a plane. Each equation and its partial derivatives define the peculiar combinations among the used parameters. Once mapped back to the space domain, the final image has provided a grouping of the struc- tures in two superimposed blocks with an irregular interface located at 2 km mean depth. Based on drilling data, subsurface stratigraphy and recent seismic activity, the interface between the two blocks has been interpreted in terms of a substantial change in the rocks rheology inside the Solfatara-Pisciarelli volcano-geothermal system, namely the brittle-to-ductile transition.332 520 - PublicationOpen AccessDeep Electrical Resistivity Tomography for a 3D picture of the most active sector of Campi Flegrei caldera(2019-10-22)
; ; ; ; ; ; ; ; ; The central sector of the Campi Flegrei volcano, including the Solfatara maar and Pisciarelli fumarole field, is currently the most active area of the caldera as regards seismicity and gaseous emissions and it plays a significant role in the ongoing unrest. However, a general volcano-tectonic reconstruction of the entire sector is still missing. This work aims to depict, for the first time, the architecture of the area through the application of deep Electrical Resistivity Tomography. We reconstructed a three-dimensional resistivity model for the entire sector. Results provide useful elements to understand the present state of the system and the possible evolution of the volcanic activity and shed solid bases for any attempt to develop physical-mathematical models investigating the ongoing phenomena.77 41