Aseismic strain episodes at Campi Flegrei Caldera, Italy

Abstract. Since 2004 a research project has been developed to monitor subsurface deformation of Italian volcanoes using borehole strainmeters and long-baseline tiltmeters. Six Sacks-Evertson dilatometers were installed around Campi Flegrei caldera Vesuvius during 2004–2005 (Scarpa et al., 2007), in 2008 these instruments supplemented by two arrays 28–280 m long water-tube tiltmeters underground tunnels. Relevant strainmeter tiltmeter data have collected analysed from the near recent unrest episodes. In period strain, tilt GPS indicate onset surface that accompanied low rate vertical displacement continued 2006, corresponding an increase CO2 emission. This strain episode preceded microseismic activity few months, as was observed also significant inflation 1982. Other transient episodes occurred October which swarm VT (Volcano-Tectonic) LP (Long Period) events, 2009, at time renewed gas emission Solfatara, again March 2010, several minutes before seismic swarm. The scale events ranges some hours days, putting tight constraints on origin ground uplifts Flegrei. Their location is compatible with source inferred term signals, located about 4 km beneath Pozzuoli. A proposed mechanism for aseismic they are associated magma growth reservoirs occasional pressure relief leakage gas.