Friday, November 29, 2013

(Geophysical Research Letters, Vol. 40, 
1–5, doi:10.1002/2013GL058132, 2013)

Giancarlo Ciotoli, Giuseppe Etiope, Fabio Florindo, 
Fabrizio Marra, Livio Ruggiero and Peter E. Sauer

An interesting article, recently published, on gas emissions near the Rome's international airport, showing the importance of the knowledge of the geological features of the subsoil before its use for man-made works.
This is the final remark of the paper (thanks to Fabio Florindo, IAPG member):

"...In the absence of deformation in the Holocene cover, however, the gas emissions may be triggered by drilling operations, disrupting the impermeable cover and allowing the pressured gas to reach the surface. Future drilling and ground excavations in the Tiber delta (including the airport) should be based on accurate knowledge of gas distribution in the geologic substrate...".

On 24 August 2013 a sudden gas eruption from the ground occurred in the Tiber river delta, nearby Rome’s international airport of Fiumicino. We assessed that this gas, analogous to other minor vents in the area, is dominantly composed of deep, partially mantle-derived CO2, as in the geothermal gas of the surrounding Roman Comagmatic Province. Increased amounts of thermogenic CH4 are likely sourced from Meso-Cenozoic petroleum
systems, overlying the deep magmatic fluids. We hypothesize that the intersection of NE-SW and N-S fault systems, which at regional scale controls the location of the Roman volcanic edifices, favors gas uprising through the impermeable Pliocene and deltaic Holocene covers. Pressurized gas may temporarily be stored below these covers or within shallower sandy, permeable layers. The eruption, regardless the triggering cause—natural or man-made, reveals the potential hazard of gas-charged sediments in the delta, even at distances far from the volcanic edifices.