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Borgia, Andrea
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Borgia, Andrea
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- PublicationRestrictedSeismogenic potential of withdrawal-reinjection cycles: Numerical modelling and implication on induced seismicity(2020)
; ; ; ; ; ; ; ; ; ; ; Induced seismicity can be associated to the activity of fluid withdrawal and injection from/into the shallow crust (fracking, wastewater disposal into the deep crust, Enhanced Geothermal Systems technology, fluid extraction in oil fields and geothermal power plants). Long-term injection of large volumes of fluids is normally associated with induced seismicity, but the effect of withdrawal-reinjection in the same reservoir is less known, at least regarding its relation to simple injection. However, it is common experience worldwide that small (i.e. 10 MW or less) geothermal plants with withdrawal and re-injection of fluids in the same reservoir are mostly not associated with significant induced/triggered seismicity. This paper aims at understanding how to discriminate, on a numerical modelling basis, the seismogenic potential of withdrawal-reinjection with respect to injection only. With this aim, we analysed the induced pressure changes, the perturbed volumes of rocks and the potential for induced seismicity due to these operations. A set of simulations of injection or withdrawal-reinjection cycles, obtained by using the numerical code TOUGH2®, is applied to simple models of geothermal reservoirs, with varying permeability and lateral boundary constraints. For each permeability model, we then compare the time growth of perturbed volumes obtained with withdrawal-reinjection cycles to those obtained during simple injection, using the same flow rates. The size of perturbed volumes is then related to the maximum magnitude of induced/triggered seismicity, using models accredited in recent literature. Our results show that, for all models, withdrawal-reinjection is by far less critical than simple injection, because the perturbed volumes are remarkably smaller and remain constant over the simulated time, so minimizing the likelihood of interference with seismogenic faults. These results have significant implications for geothermal projects, and in the assessment of the potential risk related to fluid stimulation and induced seismicity.475 2 - PublicationOpen AccessVolcanic spreading forcing and feedback in geothermal reservoir development, Amiata Volcano, Italia(2014)
; ; ; ; ; ; ; ; ;Borgia, A.; EDRA ;Mazzoldi, A.; UMSNH-IIM, Instituto de Investigaciones en Ciencias de la Tierra, Edif. "U" Ciudad Universitaria CP 58060, Morelia, Mich., México ;Brunori, C. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Allocca, C.; EDRA via di Fioranello 31, 00134 Roma, Italia ;Delcroix, C.; EDRAvia di Fioranello 31, 00134 Roma, Italia ;Micheli, L.; Regione Toscana, via di Novoli 26, Firenze, 50127 Italia. ;Vercellino, A.; Dipartimento di Scienze della Terra, Università degli Studi di Milano, via Botticelli 23, Milano, 20133 Italia. ;Grieco, G.; Dipartimento di Scienze della Terra, Università degli Studi di Milano, via Botticelli 23, Milano, 20133 Italia.; ; ; ; ; ; ; We made a stratigraphic, structural and morphologic study of Amiata Volcano in Italy. We find that the edifice is dissected by intersecting grabens that accommodate the collapse of the higher sectors of the volcano. In turn, a number of compressive structures and diapirs exist all around the margin of the volcano. These structures create an angular drainage pattern, with stream damming and captures, and a set of lakes within and around the volcano. We interpret these structures as the result of volcanic spreading of the edifice of Amiata onto its weak substratum, formed by the late Triassic evaporites (Anidriti of Burano) and the Middle-Jurassic to Early-Cretaceous clayey chaotic complexes (Ligurian Complex). Regional doming created a slope in the basement forcing the outward flow and spreading of the ductile layers below the volcano. We model the dynamics of spreading with a scaled lubrication approximation of the Navier Stokes equations, and numerically study a solution. In the model we include simple functions for volcanic deposition and surface erosion that change the topography over time. Scaling indicates that spreading at Amiata could still be active. The numerical solution shows that, as the central part of the edifice sinks into the weak basement, diapiric structures of the underlying formations form around the base of the volcano. Deposition of volcanic rocks within the volcano and surface erosion away from it both enhance spreading. In addition, a sloping basement may constitute a trigger for the formation of trains of adjacent diapirs. Finally, we observe that volcanic spreading has created ideal heat traps that constitute todays’ exploited geothermal fields at Amiata. Normal faults generated by volcanic spreading, volcanic conduits, and direct contact between volcanic rocks (which host an extensive fresh-water aquifer) and the rocks of the geothermal field, constitute ideal pathways for water recharge during vapour extraction for geothermal energy production. We think that volcanic spreading could maintain faults in a critically stressed state, facilitating the occurrence of triggered seismicity.244 617 - PublicationOpen AccessThe growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics(2011-04-15)
; ; ; ; ; ; ;Bemis, K.; Department of Earth and Planetary Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08855, USA ;Walker, J.; Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, USA ;Borgia, A.; Department of Earth and Planetary Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08855, USA ;Turrin, B.; Department of Earth and Planetary Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08855, USA ;Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Swisher III, C.; Department of Earth and Planetary Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08855, USA; ; ; ; ; Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto- radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of morphologies encompasses almost all of those observed worldwide for cinder cones. Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of those studied) is there clear evidence of degradation with age. Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of eruption.243 331 - PublicationRestrictedVolcanic spreading of Vesuvius, a new paradigm for interpreting its volcanic activity(2005)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Borgia, A.; European Development and Research Agency ;Tizzani, P.; Istituto Nazionale di Geofisica e Vulcanologica, Osservatorio Vesuviano ;Solaro, G.; Universita` Federico II, Dipartimento di Geofisica e Vulcanologia ;Manzo, M.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente ;Casu, F.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente ;Luongo, G.; Universita` Federico II, Dipartimento di Geofisica e Vulcanologia ;Pepe, A.; Universita` Federico II, Dipartimento di Ingegneria Elettronica e delle Telecomunicazioni ;Berardino, P.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente ;Fornaro, G.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente ;Sansosti, E.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente ;Ricciardi, G. P.; Istituto Nazionale di Geofisica e Vulcanologica, Osservatorio Vesuviano ;Fusi, N.; Universita Milano-Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie ;Di Donna, G.; Comune di Torre del Greco,Vesuvius Information Office ;Lanari, R.; Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente; ; ; ; ; ; ; ; ; ; ; ; ; We integrate geologic, structural, leveling and Differential SAR Interferometry data to show that Vesuvius began to spread onto its sedimentary substratum about 3,600 years ago. Moreover, we model the detected deformation with a solution of the lubrication approximation of the Navier-Stokes equations to show that spreading may continue for about 7,200 years more. Correlation of volcanic spreading with phases of the eruptive activity suggests that Plinian eruptions, which are thought to pose the major hazard, are less likely to occur in the near future.223 110