Comparison between a 20-year terrestrial and satellite gravity data at Mt. Etna volcano (Italy)

Abstract

Gravity measurements are increasingly used for high-precision and high-resolution Earth investigation. Recent times highlight the intention to combine both terrestrial and satellite data in order to reach higher accuracy for several purposes such as geological structures determination and geoid models construction. Here we present results of a comparison between a twenty-year (2002-2022) relative and absolute gravity data collected through the Microg LaCoste FG5#238 absolute gravimeter (AG), in the framework of repeated measurements in one station at about 1750 m above sea level and the satellite gravity data provided by CNES/GRGS RL05 Earth gravity field models, from GRACE and SLR data. The comparison allows to estimate the long-term correlation between the two dataset and a remarkably good fit was found in the long-term trend, revealing gravity changes most likely due to hydrological and volcanological effects. Our study shows how the combination of terrestrial and satellite data can be used to obtain a fuller and more accurate picture of the temporal characteristics of the studied processes. The combined use of these dataset results crucial especially in a harsh, unsteady and changing environment as well as the Etna volcano.