Publication Date:
2017-04-04
Description:
The main CO2 diffuse degassing structures (DDS) of Stromboli were identified through extensive CO2 soil flux
investigations, with 3600 measurements by an accumulation chamber. These DDS extend from the nearby
crater area of Pizzo sopra la Fossa (Pizzo) to the coastal area of Pizzillo and are all associated with NE–SW
deep fractures, corresponding to the main volcano-tectonic axis of the island, some of which produced flank
eruptions in prehistoric times. In each of the four main DDS, a target area was defined covering the zone with
the highest CO2 soil flux, where periodic CO2 flux surveys were carried out. The highest CO2 release was
observed during the 2007 eruption and high flux values were recorded at both Pizzo and Pizzillo also in
moments of high prolonged Strombolian activity (high number of daily explosions observed from the craters
and/or high frequency of VLP seismic events). In order to better investigate the rate of diffuse CO2 degassing
in relation to volcanic activity, an automatic station hourly measuring CO2 soil flux and environmental
parameters (atmospheric T, P and humidity, soil moisture and T, wind speed and direction) was installed in
March 2007 at Nel Cannestrà and Rina Grande DDS. Unusual positive correlations were found at Nel
Cannestrà between gas flux and SE wind speed and at Rina Grande between gas flux and soil moisture, which
are explained by the local conditions, which favour respectively a Venturi effect and the increase in gas flux
toward the station during rains. Ten months of continuous recording confirmed the strong influence of
environmental conditions on the CO2 soil flux, but statistical data processing made it possible to recognize
clear positive anomalies expressing high rates of deep magmatic CO2 degassing. Comparison with seismic
data indicates that high CO2 fluxes are apparently correlated with increases in volcanic activity, such as
higher explosion frequency and VLP amplitude. Particularly promising is the temporal coincidence of highest
recorded flux anomaly with a major explosion that occurred during the observation period. Data confirm that
the two continuously monitored DDS are preferentially deep degassing sites, where anomalous increases of
CO2 release could represent a geochemical precursor for either high energy explosions from the craters or the
opening of flank eruptive fissures that might threaten the village of Stromboli.
Description:
In press
Description:
1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
Description:
JCR Journal
Description:
reserved
Keywords:
Stromboli
;
diffuse CO2 fluxes
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
