GNGTS 2016 - Atti del 35° Convegno Nazionale

258 GNGTS 2016 S essione 1.3 Reynold number. (Keszthelyi and Self, 1998; Costa and Macedonio, 2005). In this work, using a variable Reynolds number, we can conclude that the transition from laminar flow to turbulent flow can take place locally within the channel near the solid boundary, where the temperature gradient rises, in correspondence of which the Reynold number can assume values much higher than the channel isothermal center. References Baloga, S., Spudis, P., and Guest, J.; 1995: The dynamics of rapidly emplaced terrestrial lava flows and implications for planetary volcanism, J. Geophys. Res., 100 , 24 509–24 519,. Costa, A., Macedonio, G.; 2003: Viscous heating in fluids with temperature-dependent viscosity: implications formagma flows . Nonlinear Process. Geophys., 10 , (6), 545-555. Costa, A., and G. Macedonio; 2005: Numerical simulation of lava flows based on depth-averaged equations , Geophys. Res. Lett., 32 , L05304, doi:10.1029/2004GL021817. Filippucci, M., A. Tallarico, and M. Dragoni; 2010: A three-dimensional dynamical model for channeled lava flow with nonlinear rheology , J Geophys Res, 115 , B05,202, doi:10.1029/2009JB006335. Filippucci, M., A.~Tallarico, and M.~Dragoni; 2013: Role of heat advection in a channeled lava flow with power law , J Geophys Res, 118 , 6, 2764–2776, doi:10.1002/jgrb.50136. Keszthely, L. and Self, S.; 1998: Some physical requirements for the emplacement of long basaltic lava flows , J. Geophys. Res., 103 , 27 447–27 464. Patankar, S.; 1980: Numerical heat transfer and fluid flow, series in computational methods in mechanics and thermal sciences , MAC Graw Hill. Piombo, A., and M. Dragoni; 2011: Role of viscous dissipation in the dynamics of lava flows with power-law rheology , J Volcanol Geoth Res, 206 , 88-95, doi:10.1016/j.jvolgeores.2011.06.014. Array detection of hydrothermal tremor in Campi Flegrei volcanic area D. Galluzzo 1 , M. La Rocca 2 1 Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy 2 Università della Calabria, Cosenza, Italy Introduction. Campi Flegrei caldera is an active volcanic area located in southern Italy, west of Naples. Two caldera collapses (Campanian Ignimbrite, 39 ka; Neapolitan Yellow Tuff (NYT), 15 ka) defined its present structural setting (Selva et al. , 2011). In the past 15 ka, volcanic activity has been concentrated within NYT caldera and the last eruption occurred in 1538 (Mt. Nuovo eruption) after a long period of quiescence. Campi Flegrei caldera is one of the highest risk volcanic area in the world. A large ground inflation in 1982–1984 was followed by a subsidence period lasting about 20 years, until a new uplift phase started in 2006. Geochemical data collected during the last two decades indicate that a change in the hydrothermal system is ongoing (Chiodini et al. , 2012). Low magnitude volcano tectonic seismic events mostly characterized the seismicity of the last fifteen years (Galluzzo et al. , 2016), while Low Frequency events (hereafter LF) were detected only during the year 2006 (Saccorotti et al. , 2007). Since the current status of the volcano is considered as “unrest”, the local seismic network was improved in order to detect seismic signals associated with volcanic activity reawakening (La Rocca and Galluzzo, 2016). LF events and volcanic tremor are observed at hundreds of active volcanoes worldwide (McNutt, 2005) but, due to the high background noise (Del Pezzo et al. , 2013), the detection of signals characterized by emergent onset and low amplitude like volcanic tremor is a very difficult task in the investigated area. To further improve the detection of coherent signals a dense short period array named ARF was installed in 2010 in an underground environment (La Rocca and Galluzzo, 2012). Nowadays, the seismic network is composed by more than 30 digital seismic stations equipped with broad band, short period and accelerometric sensors and