Publication Date:
2021-07-14
Description:
Volcanic risk at Vesuvius is one of the highest in the world due to the ~670,000 inhabitants living
in the Red Zone, the area exposed to both pyroclastic flows and tephra fallout, to be evacuated
before renewal of any eruptive activity. The national emergency plan for Vesuvius builds its risk
zonation on a scenario similar to the last sub-Plinian eruption, which occurred in 1631. This study
aims at providing new insights on the geometry of the caldera associated with this historical
eruption. The impact of past Vesuvius eruptions on present-day soil CO2 concentration has been
investigated by means of an extended geochemical survey carried out for identifying the circulation
pathways of hydrothermal fluids inside the volcano. We performed 4,018 soil CO2 concentration
measurements over the whole Somma-Vesuvius volcanic complex, covering an area of 50 km2.
Besides relatively low values, the results show a significant spatial CO2 concentration
heterogeneity over Somma-Vesuvius ranging from the atmospheric value (~400 ppm) up to ~24,140 ppm. The summit of Vesuvius shows an area with anomalous CO2 concentrations well
matching the crater rim of the 1906 eruption. Along the cone flanks, secondary CO2 anomalies
highlight a roughly circular preferential pathway detected along 8 radial profiles at distances
between ~840 m and ~1,150 m from the bottom of the present-day crater resulting from the last
eruption in 1944. In depth review of the available literature highlights an agreement between this
circle-like shaped anomaly and the 1631 sub-Plinian eruption caldera boundary. Indeed, based on
the historical chronicles the depression produced by the 1631 eruption had a diameter of 1,686 m,
whereas the CO2 circular anomaly indicates a diameter of 1,956 m. Finally, the results were
compared with a 3-D density model obtained from a recent gravity survey that corroborates both
the literature and the CO2 data in terms of potential buried structure at the base of the Vesuvius
cone.
Description:
Published
Description:
43-56
Description:
1V. Storia eruttiva
Description:
JCR Journal
Keywords:
Somma-Vesuvius
;
soil CO2 concentration
;
1631 sub-Plinian eruption.
;
carbon dioxide
;
caldera.
;
04.08. Volcanology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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