Abstract. Since 1981, relative gravity measurements have routinely carried
out at the Campi Flegrei caldera, a densely populated area. The gravity
network also includes two absolute stations periodically measured with a
laboratory absolute gravimeter, which does not permit field measurements. At the end of 2014, the Osservatorio Vesuviano, Section of Napoli of the
Istituto Nazionale di Geofisica e Vulcanologia (INGV-OV), acquired a
portable absolute gravimeter that allows field operations on outdoor sites.
Therefore, in 2015 a dense absolute gravity network was established in Campi
Flegrei. This will permit an advanced approach for volcano monitoring. The
net consists of 36 stations, 34 of which located inside the caldera and
placed upon or very close to gravity stations belonging to the relative
network. Five surveys were carried out on June 2015, on February and
November 2017, on October 2018 and on October 2019. The comparison with
height changes suggests that significant Δg are partly due to the
uplift occurred over the same time intervals and mostly to shallow processes
associated to the dynamic of the local hydrothermal system. The comparison
with the gradients observed during the last large uplift (1982–1984) and the
following subsidence (1985–2003) confirms this observation. These results
suggest that the present activity may be due to a transient or pulsating
phenomenon as the alternating recharge/discharge of fluids in the surface
hydrothermal system. Gravity changes detected by absolute measurements are
in good agreement with those obtained by relative ones, and confirms the
feasibility of this methodology for volcano monitoring. Finally, they also
encourage replacing the relative networks with absolute ones, with all the
consequent advantages.
Gsolve, a Python computer program with a graphical user interface to transform relative gravity survey measurements to absolute gravity values and gravity anomalies
