Ground-Penetrating Radar technique to investigate historic eruptions on the Mt. Etna volcano (Sicily, Italy)

In the present paper we demonstrate the capability of different remote sensing techniques to reconstruct the evolutionary history of the lava flows on the Mt. Etna volcano. A preliminary approach to the sites, based on aerial photogrammetry, DEM, and topographic analyses, supports an intense GPR (Ground Penetrating Radar) survey in several sites with different stratigraphical characteristics. The GPR measurements are performed with a bistatic system equipped with both 500 and 1000 MHz antennas. The use of different polarizations (TE, TM, Cross-Tx, and Cross-Rx) allow to extract subsurface features information having 3D geological structure reconstruction, electromagnetic nature information and properties of buried reflectors. This preliminary study highlights how the GPR technique provides, non-destructively, useful data to study the mechanisms of emplacement and the correlated hazard. Furthermore, if an inactive lava tubes can only be detected after the collapse of their vault, the use of GPR, on the contrary, could help to locate buried undamaged lava tubes and to measure their dimensions, providing useful structural information. Lava tubes, also, strongly influences the development of lava fields and the hazard connected with them, because they keep the lava thermally isolated causing a propagation longer than it would have done in an open channel. Additionally, the combined use of different remote sensing techniques can be useful to better estimate the thickness of the lava fields, giving precious data about the nature of the flow. Finally, the results highlight the importance of this combined approach to evaluate different physical parameters at the same time.