[1] The Aeolian volcanoes are located between the Southern Tyrrhenian Sea back arc and the Calabrian Arc forearc region. Structural, geochemical and seismological data indicate that the early phases of volcanic activity (1.3 Myr) developed in the western sector along WNW-ESE tear faults controlling the southeastward migration of the forearc -back arc system. This magmatism ceased when delamination processes affected the Calabrian Arc. At 0.8 Myr, the volcanism migrated southeastward and concentrated on the ''new'' formed NNW-SSE tear faults related to the postsubduction extensional strain. The compressive strain deduced by focal mechanism of earthquakes in the western sector explains the volcanism ending. The still active volcanism in the central and eastern sectors develops on a NNW-SSE striking lithospheric discontinuity that crosses the ring-shaped volcanic belt. Moho upwelling occurs in the area of active volcanism. Fault-slip data and focal mechanisms from M > 5 earthquakes indicate that the NNW-SSE discontinuity moves in response to an oblique (strikeslip/normal) stress related to a WNW-ESE extension. This direction of extension is consistent with that of the forearc region, where thrust-type events are lacking and the last compressive phases occurred during Pliocene. The later phases of the Aeolian volcanism are related to the melting of shallower source(s) consistent with a continental rift magmatism. The Aeolian Islands represent a postcollisional, rift-type volcanism emplaced in an older collision zone.

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A two-dimensional active seismic experiment was performed on Mount Vesuvius: Explosive charges were set off at three sites, and the seismic signal along a dense line of 82 seismometers was recorded. A high-velocity basement, formed by Mesozoic carbonates, was identified 2 to 3 kilometers beneath the volcano. A slower ( P -wave velocity V P ≃ 3.4 to 3.8 kilometers per second) and shallower high-velocity zone underlies the central part of the volcano. Large-amplitude late arrivals with a dominant horizontal wave motion and low-frequency content were identified as a P to S phase converted at a depth of about 10 kilometers at the top of a low-velocity zone ( V P < 3 kilometers per second), which might represent a melting zone.

Despite their importance for eruption forecasting the causes of seismic rupture processes during caldera unrest are still poorly reconstructed from seismic images. Seismic source locations and waveform attenuation analyses of earthquakes in the Campi Flegrei area (Southern Italy) during the 1983–1984 unrest have revealed a 4–4.5 km deep NW-SE striking aseismic zone of high attenuation offshore Pozzuoli. The lateral features and the principal axis of the attenuation anomaly correspond to the main source of ground uplift during the unrest. Seismic swarms correlate in space and time with fluid injections from a deep hot source, inferred to represent geochemical and temperature variations at Solfatara. These swarms struck a high-attenuation 3–4 km deep reservoir of supercritical fluids under Pozzuoli and migrated towards a shallower aseismic deformation source under Solfatara. The reservoir became aseismic for two months just after the main seismic swarm (April 1, 1984) due to a SE-to-NW directed input from the high-attenuation domain, possibly a dyke emplacement. The unrest ended after fluids migrated from Pozzuoli to the location of the last caldera eruption (Mt. Nuovo, 1538 AD). The results show that the high attenuation domain controls the largest monitored seismic, deformation, and geochemical unrest at the caldera.

Mefite d'Ansanto, southern Apennines, Italy is the largest natural emission of low temperature CO2 rich gases, from non‐volcanic environment, ever measured in the Earth. The emission is fed by a buried reservoir, made up of permeable limestones and covered by clayey sediments. We estimated a total gas flux of ∼2000 tons per day. Under low wind conditions, the gas flows along a narrow natural channel producing a persistent gas river which has killed over a period of time people and animals. The application of a physical numerical model allowed us to define the zones which potentially can be affected by dangerous CO2 concentration at breathing height for humans. The geometry of the Mefite gas reservoir is similar to those designed for sequestering CO2 in geological storage projects where huge amounts of CO2 should be injected in order to reduce atmospheric CO2 concentration. The approach which we have used at Mefite to define hazardous zones for the human health can be applied also in case of large CO2 leakages from storage sites, a phenomena which, even if improbable, can not be ruled out.

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