Tracking the Endogenous Dynamics of the Solfatara Volcano (Campi Flegrei, Italy) through the Analysis of Ground Thermal Image Temperatures

Abstract

In the last decades, thermal infrared ground-based cameras have become effective tools to detect significant spatio-temporal anomalies in the hydrothermal/volcanic environment, possibly linked to impending eruptions. In this paper, we analyzed the temperature time-series recorded by the ground-based Thermal Infrared Radiometer permanent network of INGV-OV, installed inside the Solfatara-Pisciarelli area, the most active fluid emission zones of the Campi Flegrei caldera (Italy). We investigated the temperatures’ behavior in the interval 25 June 2016–29 May 2020, with the aim of tracking possible endogenous hydrothermal/volcanic sources. We performed the Independent Component Analysis, the time evolution estimation of the spectral power, the cross-correlation and the Changing Points’ detection. We compared the obtained patterns with the behavior of atmospheric temperature and pressure, of the time-series recorded by the thermal camera of Mt. Vesuvius, of the local seismicity moment rate and of the CO2 emission flux. We found an overall influence of exogenous, large scale atmospheric effect, which dominated in 2016–2017. Starting from 2018, a clear endogenous forcing overcame the atmospheric factor, and dominated strongly soil temperature variations until the end of the observations. This paper highlights the importance of monitoring and investigating the soil temperature in volcanic environments, as well as the atmospheric parameters.

Tidal Modulation of Hydrothermal Tremor: Examples From Ischia and Campi Flegrei Volcanoes, Italy

“…Most of these components are related to atmospheric factors, whereas only one was attributed to endogenous processes (Caputo et al, 2020). A similar analysis also evidenced the concomitance of external and internal forcing in modulating the ground temperature time-series in the band 30-50 days (Cusano et al, 2021).…”

“…Our results, together with those from De Lauro et al ( 2013), who evidenced semi-diurnal and diurnal components, indicate a broad tidal spectrum of the hydrothermal tremor. Some of the long-term tidal periodicities have also been detected in other geophysical observables, e.g., ground deformation (De Lauro et al, 2018;Ricco et al, 2019;Petrosino et al, 2020) and temperature time-series (Caputo et al, 2020;Cusano et al, 2021) as well as in rates of VT earthquakes , suggesting that these different tides and, in particular, the monthly and fortnightly constituents influence several manifestations of the caldera activity.…”

“…The influence of Earth tides at the Campi Flegrei volcanic system has been evidenced on different time scales. Periodicities matching short (semidiurnal, diurnal) to long (fortnightly, monthly) term tidal constituents have been detected in several geophysical data: gravity changes (Berrino and Corrado, 1991), ground deformation (De Lauro et al, 2018;Ricco et al, 2019;Petrosino et al, 2020), ground temperature (Caputo et al, 2020;Cusano et al, 2021), LP and VT earthquake rates and energy (De Lauro et al, 2012;, and hydrothermal tremor (De Lauro et al, 2013).…”

Identifying the Fingerprint of a Volcano in the Background Seismic Noise from Machine Learning-Based Approach

“…The sustained hydrothermal tremor, mainly peaked at 1 Hz, is generated by the shallow geothermal aquifer nearby the Solfatara crater [36,41]. Here, there is a consistent flux of hot fluids mixed with meteoric water coming from the boiling mud pools and the Pisciarelli fumaroles [42,43]. Moreover, LP events appear to be the enhancement of the hydrothermal tremor under suitable conditions, sharing the same polarization patterns [15,44]; they are associated with the vibrations of the shallow branched hydrothermal system, induced by well-sustained fluid circulation.…”

Modulation of Ground Deformation and Earthquakes by Rainfall at Vesuvius and Campi Flegrei (Italy)

“…A new episode of ground uplift started in 2005 and it is still ongoing with accelerated rate during 2011-2013 and subsequently since September 2020; to date the overall vertical deformation is about 0.8 m. Uplift episodes are likely related to the pressurization of hot fluids (CO 2 and H 2 O) exsolving from a deep magmatic body towards a shallow hydrothermal system where they mix with meteoric components (Gresse et al, 2017). Hydrothermal fluids and gases are released at the surface of Solfatara crater and Pisciarelli fumarolic field, the most thermally active sites of the caldera (Caputo et al, 2020;Cusano et al, 2021). Uplifts are accompanied by seismicity consisting of both sequences of VT earthquakes and LP events.…”