Ground tilt monitoring at Phlegraean Fields (Italy): a methodological approach

Among geodetic methods used for monitoring ground deformation in volcanic areas, tiltmetry represents the
most rapid technique and therefore it is used by almost all the volcanological observatories in the world. The deformation
of volcanic building is not only the result of endogenous causes (i.e. dykes injection or magma rising),
but also non-tectonic environmental factors. Such troubles cannot be removed completely but they can be
reduce. This article outlines the main source of errors affecting the signals recorded by Phlegraean tilt, network,
such as the dependence of the tilt response on temperature and to the thermoelastic effect on ground deformation.
The analytical procedure used to evaluate about such errors and their reduction is explained. An application
to data acquired from the tilt network during two distinct phases of ground uplift and subsidence of the Phlegraean
Fields is reported.