Monitoring diffuse volcanic degassing during volcanic unrests: the case of Campi Flegrei (Italy)

Abstract

In volcanoes with active hydrothermal systems, diffuse CO2 degassing may constitute the primary mode of volcanic degassing. The monitoring of CO2 emissions can provide important clues in understanding the evolution of volcanic activity especially at calderas where the interpretation of unrest signals is often complex. Here, we report eighteen years of CO2 fluxes from the soil at Solfatara of Pozzuoli, located in the restless Campi Flegrei caldera. The entire dataset, one of the largest of diffuse CO2 degassing ever produced, is made available for the scientific community. We show that, from 2003 to 2016, the area releasing deep-sourced CO2 tripled its extent. This expansion was accompanied by an increase of the background CO2 flux, over most of the surveyed area (1.4 km2), with increased contributions from non-biogenic source. Concurrently, the amount of diffusively released CO2 increased up to values typical of persistently degassing active volcanoes (up to 3000 t d−1). These variations are consistent with the increase in the flux of magmatic fluids injected into the hydrothermal system, which cause pressure increase and, in turn, condensation within the vapor plume feeding the Solfatara emission.

Reservoir Structure and Hydraulic Properties of the Campi Flegrei Geothermal System Inferred by Audiomagnetotelluric, Geochemical, and Seismicity Study

“…We interpret such gaps in the clay cap as due to fracture zones within which pressurized gas escapes from a deeper reservoir as observed in other geothermal system (Rodriguez et al, ). This interpretation is supported by two lines of observations: (i) gas emissions correlate to NW‐SE trending fault/fracture systems crossing the eastern side of the Solfatara crater and the Pisciarelli area (Cardellini et al, ; Isaia et al, ); (ii) the presence of subvertical faults disrupting the crater volcanoclastic filling inferred down to 200–300 m bsl by seismic reflection shallow profiles (Bruno et al, ).…”

“…The data acquired at Solfatara, 403 measurements, were already published in a specific work together with the data of other 29 diffuse CO 2 flux surveys performed in the same area from 1998 to 2016 (Cardellini et al, ). According to Cardellini et al (), in the spring 2006 Solfatara crater emitted 1,242 ± 135 tons per day of CO 2 by soil diffuse degassing.…”

Insight Into Campi Flegrei Caldera Unrest Through Seismic Tremor Measurements at Pisciarelli Fumarolic Field

“…Regardless of this interpretation, after a brief period of quiet, in 2014, inflation resumed and started a period characterized by low magnitude shallow earthquakes (<2 km). At the time of writing this article the deformation measurements indicate a maximum caldera ground uplift (starting from 2004) of about 57 cm (Tamburello et al, ) and measurements of the fluxes of CO 2 in the hydrothermal areas of Pisciarelli and Solfatara (Figure ) point to a progressive escalation of the degassing rate (e.g., Aiuppa et al, ; Cardellini et al, ; Chiodini et al, ; Queißer et al, ; Tamburello et al, ).…”

“…Starting from 2004, changes in seismicity (Chiodini et al, ; D'Auria et al, ; Saccorotti et al, ), deformation (Troise et al, ; Trasatti et al, ; D'Auria et al, ; De Martino et al, ; Giudicepietro et al, ; Iannaccone et al, ), and degassing activity (Cardellini et al, ; Chiodini et al, ; Chiodini et al, ; Tamburello et al, ) became evident in the Campi Flegrei caldera. These changes were the subject of scientific investigations that resulted in a remarkable production of articles over the recent years (Amoruso et al, ; De Siena et al, ; Di Luccio et al, ; Giudicepietro et al, ; Kilburn et al, ; Zaccarelli & Bianco, ; Zollo et al, ).…”

Noble Gas and Carbon Isotope Systematics at the Seemingly Inactive Ciomadul Volcano (Eastern‐Central Europe, Romania): Evidence for Volcanic Degassing

“…The chemical and isotopic composition of the emitted fluids in active volcanoes is primarily controlled by magmatic processes, such as the injection of new magma into the plumbing system or degassing of deep mafic magma in the lower crust, or interaction with the volcanic hydrothermal systems, among others (e.g., Caracausi et al, 2003Caracausi et al, , 2013Christopher et al, 2010;Edmonds, 2008;Paonita et al, 2012Paonita et al, , 2016Sano et al, 2015). Furthermore, compositional change of the fluids may also correlate with the seismicity at regional scale (e.g., Bräuer et al, 2008Bräuer et al, , 2018Cardellini et al, 2017;Chiodini et al, 2004;Melián et al, 2012). …”