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

Within a general volcanic unrest in the densely urbanized area of Campi Flegrei caldera (Italy)
an increase in the activity of Pisciarelli hydrothermal area is occurring. The seismic amplitude of
Pisciarelli fumarolic tremor is a proxy for the fluid emission rate of the entire Solfatara‐Pisciarelli
hydrothermal system. The long‐term analysis indicates a significant increase, by a factor of ~3 of the
fumarolic tremor amplitude since May 2017. This increment matches with the trend of geochemical and
seismic parameters observed in Campi Flegrei, therefore highlighting that Pisciarelli is a key site to
monitor the volcanic unrest underway in this high‐risk caldera. The analysis of data from three closely
spaced seismic stations provided new clues about the source mechanism of the tremor. Analyzing the
fumarolic tremor amplitude we could also identify an episode of enlargement of the emission area close
to the main fumarole of Pisciarelli. We propose a monitoring system based on the fumarolic tremor
analysis, which provides real‐time information on the Pisciarelli hydrothermal activity and therefore on
the current unrest in Campi Flegrei caldera.