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http://hdl.handle.net/2122/13457
Authors: | Carapezza, Maria Luisa* Barberi, Franco* Ranaldi, Massimo* Tarchini, Luca* Pagliuca, Nicola Mauro* |
Title: | Faulting and Gas Discharge in the Rome Area (Central Italy) and Associated Hazards | Journal: | Tectonics | Series/Report no.: | 3/38 (2019) | Issue Date: | 11-Feb-2019 | DOI: | 10.1029/2018TC005247 | Keywords: | Rome region contains several zones with anomalous and hazardous emission of endogenous gas brought to the surface by deep‐reaching faults At least 10 dangerous gas blowouts from shallow wells have occurred in the Rome area in the last 30 years Alignment of soil gas anomalies and vents indicates that gas raises along faults controlled by buried Mesozoic carbonate structure |
Subject Classification: | 04.08. Volcanology 04.06. Seismology |
Abstract: | The area of Central Italy around Rome contains natural gas discharging zones and severalothers where quarrying or mining excavation removed the impervious superficial layers allowing a freehazardous discharge to the surface of endogenous gas. These gas manifestations are mostly located aboveburied structural highs of fractured Mesozoic limestones hosting the main regional aquifer and revealed bygravity anomalies. In the last decades, many gas blowouts occurred in this area, from wells whose depthranged from 10–15 to 350 m. The main component of the emitted gas is CO2with minor H2S; only in ablowout offshore of Fiumicino CH4prevailed. Several animals even of large size and two persons were killedby the emitted gas (mostly by H2S), and nearby houses were evacuated because of dangerous indoor CO2concentrations. He and CO2‐carbon isotopes suggest that gas has a deep mantle signature, as indicatedfor Fiumicino gas by N2isotopic composition and N2/36Ar ratios. Gas rising from depthfirst accumulates inthe buried Mesozoic limestone reservoir, and from there it escapes along deep‐reaching faults. On its way tothe surface, the gas dissolves into and pressurizes any encountered confined aquifer, which may thenproduce a gas blowout when reached by wells. The main direction of the gas feeding faults was estimatedthrough the alignment of visible gas emissive points, the shape of the positive anomalies in soil CO2fluxmaps, and new structural‐geological observations,finding that they correspond mostly to the mainorientation of the underlying limestone structural high. |
Appears in Collections: | Article published / in press |
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Blowouts_Carapezza_et_al-2019-Tectonics.pdf | 8.23 MB | Adobe PDF | View/Open | |
LicenseCopy_TECT21054_2019-02-11.pdf | AGU Permission to Deposit an Article in an Institutional Repository | 37.35 kB | Adobe PDF | View/Open |
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