Abstract
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 and Vesuvius during 2004–2005 (Scarpa et al., 2007), and in 2008 these instruments were supplemented by two arrays of 28–280 m long water-tube tiltmeters in underground tunnels. Relevant strainmeter and tiltmeter data have been collected and analysed from the instruments installed near Campi Flegrei caldera during the recent unrest episodes. In the period 2004–2005 strain, tilt and GPS data from Campi Flegrei indicate the onset of surface deformation that accompanied a low rate of vertical displacement that continued to 2006, corresponding to an increase of CO2 emission. This strain episode preceded caldera microseismic activity by a few months, as was observed also during a significant inflation episode in 1982. Other transient strain episodes occurred in October 2006, which were accompanied by a swarm of VT (Volcano-Tectonic) and LP (Long Period) events, in 2009, at the time of renewed gas emission activity at Solfatara, and again in March 2010, several minutes before a seismic swarm. The time scale of these transient strain events ranges from some hours to several days, putting tight constraints on the origin of ground uplifts at Campi Flegrei. Their location is compatible with a source inferred from long term deformation signals, located about 4 km beneath Pozzuoli. A proposed mechanism for these aseismic strain episodes is that they are associated with magma growth in reservoirs with occasional pressure relief associated with the leakage of gas.
Highlights
Campi Flegrei is an active caldera, with a diameter exceeding 10 km, located close to the city of Naples in southern Italy
74 cm of uplift occurred between 1950 and 1952 (Del Gaudio et al, 2010), but without any report or record of associated seismic activity. Slow subsidence followed this period of uplift interrupted in 1970–1972 and in 1982–1984 by rapid (≈ 1.5 m) inflation episodes, the first accompanied by moderate low seismicity (Corrado et al, 1977) with only few events felt by residents, whereas the second was accompanied by relatively intense swarms of volcano tectonic (VT) earthquakes (Barberi et al, 1986)
Subsidence has been recorded for several years, interrupted by some small mini-uplift episodes, each with a duration of several weeks, all accompanied by seismic swarms of low magnitude VT events
Summary
Campi Flegrei is an active caldera, with a diameter exceeding 10 km, located close to the city of Naples in southern Italy. 74 cm of uplift occurred between 1950 and 1952 (Del Gaudio et al, 2010), but without any report or record of associated seismic activity Slow subsidence followed this period of uplift interrupted in 1970–1972 and in 1982–1984 by rapid (≈ 1.5 m) inflation episodes, the first accompanied by moderate low seismicity (Corrado et al, 1977) with only few events felt by residents, whereas the second was accompanied by relatively intense swarms of volcano tectonic (VT) earthquakes (Barberi et al, 1986). This seismic activity caused alarm in the population and a spontaneous partial evacuation of the city of Pozzuoli (44 000 residents). The last mini-uplift episode had an unusual duration, starting from 2004 and continuing until 2013, with a total
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
