http://hdl.handle.net/2122/199 2013-05-22T18:15:23Z http://hdl.handle.net/2122/6838 Title: Questo caldo, caldo, caldo mondo Authors: Carapezza, M. L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; D'Addezio, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Ricci, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Barberi, F.; DSG, Univ. Roma Tre; Ranaldi, M.; DSG, Univ. Roma Tre Abstract: La mostra consente fin dal suo inizio di “entrare” nel mondo degli spettacolari fenomeni geotermici. Immagini di geyser, pozze di fango ribollente, fumarole, acque termali dai colori più improbabili, incrostazioni multicolori e affascinanti cristalli, provenienti da varie parti del mondo accompagneranno i visitatori alla scoperta delle caratteristiche naturalistiche del fenomeno. Ad arricchire l'esposizione iniziale curata da Vulcano Esplorazioni, un video con immagini raccolte in varie parti del pianeta, eccezionali campioni di minerali di origine idrotermale provenienti dal Museo di Storia Naturale di Milano e diorami esplicativi, in scala e ridotti. Ricostruzioni, schemi ed exhibit facilitano la comprensione del meccanismo fisico che scatena questi fenomeni. La parte scientifica, curata in particolare dall’INGV, ripercorre anche le esperienze pionieristiche di Larderello, ricostruendo il primo esperimento del 1904 di produzione di energia elettrica da vapore geotermico. Il percorso museale illustra anche il grande potenziale energetico presente soprattutto in Italia, il paese più caldo d'Europa, offerto dal calore della Terra, un’energia rinnovabile e pulita. L'esibizione termina con uno spettacolare filmato in 3D. 2009-10-22T22:00:00Z http://hdl.handle.net/2122/2872 Title: The permanent thermal infrared network for the monitoring of hydrothermal activity at the Solfatara and Vesuvius volcanoes. Authors: Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Augusti, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Minopoli, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Terranova, C. Abstract: In this paper we describe the activities carried out for the realization of an image surveillance systems, in the thermal infrared (TIR) wavelengths range, for the continuous long-term monitoring of the shallow thermal structure of the Solfatara (Campi Flegrei) and Vesuvius volcanoes. The system implementation was pursued by both acquiring and integrating all the technological instruments necessary to operate an instrumental system constituted by: a network of remote monitoring stations; a transmission system for the image data centralization; a control unit for both the remote stations control and the acquired data processing. The analysis of two-years long series of IR images collected at the Solfatara allowed us to evaluate, in the observation period, the main thermal features of the major fumarole field located in the SE inner slope of the Solfatara crater. 2006-12-31T23:00:00Z http://hdl.handle.net/2122/2580 Title: A thermal pressurization model for the spontaneous ...: 2. Traction evolution and dynamic parameters Authors: Bizzarri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Cocco, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: We investigate the dynamic traction evolution during the spontaneous propagation of a 3-D earthquake rupture governed by slip-weakening or rate- and state-dependent constitutive laws and accounting for thermal pressurization effects. The analytical solutions as well as temperature and pore pressure evolutions are discussed in the companion paper by Bizzarri and Cocco. Our numerical experiments reveal that frictional heating and thermal pressurization modify traction evolution. The breakdown stress drop, the characteristic slip-weakening distance, and the fracture energy depend on the slipping zone thickness (2w) and hydraulic diffusivity (w). Thermally activated pore pressure changes caused by frictional heating yield temporal variations of the effective normal stress acting on the fault plane. In the framework of rate- and state-dependent friction, these thermal perturbations modify both the effective normal stress and the friction coefficient. Breakdown stress drop, slip-weakening distance, and specific fracture energy (J/m2) increase for decreasing values of hydraulic diffusivity and slipping zone thickness. We propose scaling relations to evaluate the effect of w and w on these physical parameters. We have also investigated the effects of choosing different evolution laws for the state variable. We have performed simulations accounting for the porosity evolution during the breakdown time. Our results point out that thermal pressurization modifies the shape of the slip-weakening curves. For particular configurations, the traction versus slip curves display a gradual and continuous weakening for increasing slip: in these cases, the definitions of a minimum residual stress and the slip-weakening distance become meaningless. 2005-12-31T23:00:00Z http://hdl.handle.net/2122/2579 Title: A thermal pressurization model for the spontaneous dynamic rupture propagation on a three-dimensional fault: 1. Methodological approach Authors: Bizzarri, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Cocco, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: We investigate the role of frictional heating and thermal pressurization on earthquake ruptures by modeling the spontaneous propagation of a three-dimensional (3-D) crack on a planar fault governed by assigned constitutive laws and allowing the evolution of effective normal stress. We use both slip-weakening and rate- and state-dependent constitutive laws; in this latter case we employ the Linker and Dieterich evolution law for the state variable, and we couple the temporal variations of friction coefficient with those of effective normal stress. In the companion paper we investigate the effects of thermal pressurization on the dynamic traction evolution. We solve the 1-D heat conduction equation coupled with Darcy’s law for fluid flow in porous media. We obtain a relation that couples pore fluid pressure to the temperature evolution on the fault plane. We analytically solve the thermal pressurization problem by considering an appropriate heat source for a fault of finite thickness. Our modeling results show that thermal pressurization reduces the temperature increase caused by frictional heating. However, the effect of the slipping zone thickness on temperature changes is stronger than that of thermal pressurization, at least for a constant porosity model. Pore pressure and effective normal stress evolution affect the dynamic propagation of the earthquake rupture producing a shorter breakdown time and larger breakdown stress drop and rupture velocity. The evolution of the state variable in the framework of rate- and state-dependent friction laws is very different when thermal pressurization is active. In this case the evolution of the friction coefficient differs substantially from that inferred from a slip-weakening law. This implies that the traction evolution and the dynamic parameters are strongly affected by thermal pressurization. 2005-12-31T23:00:00Z http://hdl.handle.net/2122/536 Title: Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems Authors: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Costa, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Werner, C.; Institute of Geological and Nuclear Sciences, Taupo, New Zealand Abstract: We present a reliable methodology to estimate the energy associated with the subaerial diffuse degassing of volcanic-hydrothermal fluids. The fumaroles of 15 diffuse degassing structures (DDSs) located in eight volcanic systems in the world were sampled and analyzed. Furthermore, each area was measured for soil temperature gradients and for soil CO2 fluxes. The results show that each hydrothermal or volcanic system is characterized by a typical source fluid which feeds both the fumaroles and diffuse degassing through the soil. Experimental data and the results of physical numerical modeling of the process demonstrate that the heat released by condensation of steam at depth is almost totally transferred by conduction in the uppermost part of the soil. A linear relationship is observed between the log of the steam/gas ratio measured in the fumaroles and the log of the ratio between soil thermal gradient and soil-gas flux. The main parameter controlling this relation is the thermal conductivity of the soil (Kc). For each area, we computed the values of Kc which range from 0.4 to 2.3 W m 1 C 1. Using the CO2 soil fluxes as a tracer of the deep fluids, we estimated that the total heat released by steam condensation in the systems considered varies from 1 to 100 MW. 2004-12-31T23:00:00Z http://hdl.handle.net/2122/376 Title: Active geodynamics of the central Mediterranean Sea: Tensional tectonic evidences in western Sicily from mantle-derived helium Authors: Caracausi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Favara, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Nuccio, P. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Paonita, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Rizzo, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: We report results on the measured high 3He/4He isotope ratio in western Sicily, interpreted together with the heat data. The study of this sector of the Europe-Africa interaction is crucial to a better understanding of the tectonics and the geodynamical evolution of the central Mediterranean area. The estimated mantle-derived helium fluxes in the investigated areas are up to 2–3 orders of magnitude greater than those of a stable continental area. The highest flux, found in the southernmost area near the Sicily Channel, where recent eruptions of the Ferdinandea Island occurred 20 miles out to sea off Sciacca, has been associated with a clear excess of heat flow. Our results indicate that there is an accumulation of magma below the continental crust of western Sicily that is possibly intruding and out-gassing through roughly N-S trending deep fault systems linked to the mantle, that have an extensional component. Although the identification of these faults is not sufficiently constrained by our data, they could possibly be linked to the pre-existing faults that originated during the Mesozoic extensional-transtensional tectonic phases. 2004-12-31T23:00:00Z