Abstract
Abstract. The Campi Flegrei caldera is located in the metropolitan area of Naples (Italy) and has been undergoing different stages of unrest since 1950, evidenced by episodes of significant ground uplift followed by minor subsidence, increasing and fluctuating emission strengths of water vapor and CO2 from fumaroles, and periodic seismic crises. We deployed a scanning laser remote-sensing spectrometer (LARSS) that measured path-integrated CO2 concentrations in the Pisciarelli area in May 2017. The resulting mean CO2 flux is 578 ± 246 t d−1. Our data suggest a significant increase in CO2 flux at this site since 2015. Together with recent geophysical observations, this suggests a greater contribution of the magmatic source to the degassing and/or an increase in permeability at shallow levels. Thanks to the integrated path soundings, LARSS may help to give representative measurements from large regions containing different CO2 sources, including fumaroles, low-temperature vents, and degassing soils, helping to constrain the contribution of deep gases and their migration mechanisms towards the surface.
Highlights
Of all the volcanic calderas in the world the ∼ 12 km wide Campi Flegrei (CF) in southern Italy is arguably the one with the highest destructive potential, since it is in a state of unrest and located within an urban area of over 2 million residents, with Naples being the largest urban nucleus in the area (Fig. 1a)
The CO2 concentrations needed to estimate the CO2 flux are commonly sampled at individual points, which may miss out particular sources, such as smaller fumarolic discharges (Chiodini et al, 2015)
Given the slow, almost halted ground uplift since 2016, our result could indicate a release of deep magmatic gases towards the hydrothermal system, possibly accompanied by an increased bulk permeability of the shallow crust
Summary
Of all the volcanic calderas in the world the ∼ 12 km wide Campi Flegrei (CF) in southern Italy is arguably the one with the highest destructive potential, since it is in a state of unrest and located within an urban area of over 2 million residents, with Naples being the largest urban nucleus in the area (Fig. 1a). The amount of water vapor has increased visibly and the strongly degassing area has been considerably enlarged in the past few years (Chiodini et al, 2015). Given these major signs as well as other signs, mainly related to fluid geochemical variations at the fumaroles of Solfatara (Chiodini et al, 2015, 2016), national civil protection authorities have changed the state of CF from green (quiet) to yellow (scientific attention)
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