Publication Date:
2023-12-04
Description:
Early in the morning of 24 August, 2013, following by hours the drilling of a shallowborehole in the same spot, a
new fumarole producing emissions of CO2-rich gas, water, and mud suddenly appeared at a crossroad along the
fenced area of the Fiumicino international airport of Rome, Italy. Similar episodes have been scientifically documented
or simply reported in recent and past years. To understandwhy gases are easily entrapped in the shallow
subsurface of the Fiumicino area, we used five borehole cores drilled by us, analyzed the stratigraphy of these and
other nearby cores, acquired a 2D seismic refraction tomogram, and performed chemical and isotopic analyses of
water samples collected from aquifers intercepted by two drilled boreholes. Our boreholes were realized with
proper anti-gasmeasures as,while drilling, we recorded the presence of pressurized gases at a specific permeable
gravel level. Results showthat, in the study area, gases become mainly entrapped in a mid-Pleistocene gravel horizon
at about 40–50 m depth. This horizon contains a confined aquifer that stores the endogenous upwelling
gases. The gravel is interposed between two silty–clayey units. The lower unit, very hard and overconsolidated,
is affected by fractures that allow ascending gases to bypass the otherwise impermeable shale, permeate the
gravel, and dissolve into the aquifer. In contrast, the upper unit is impermeable to fluids and seals the gaspressurized
aquifer, which therefore constitutes a source of hazard during human activities such as well drilling,
quarrying, and various building-related excavations. As the stratigraphy of the Fiumicino area is very common in
large portions of the densely populated Roman area and as the adjacent volcanic districts are hydrothermally
active, we conclude that phenomena similar to that observed at Fiumicino could again occur both at Fiumicino
and elsewhere in the surrounding region. As a prompt confirmation of our conclusion, we signal that, while
writing this paper, new artificially-triggered degassing phenomena occurred off Fiumicino in connection with
the construction of the new harbor.
Description:
Published
Description:
53-66
Description:
4V. Vulcani e ambiente
Description:
JCR Journal
Description:
restricted
Keywords:
Mud volcano
;
gas hazard
;
drilling
;
03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
