Ground deformation patterns on Mt Etna, 1992 to 1994, inferred from GPS data

In this paper, ground deformation that occurred on Mount etna from 1992-1994 is studied using GPS data. First, problems relating to data processing of the 1993 and 1994 surveys carried out on the whole of the Mount Etna GPS network are considered. Care has been paid to the network-adjustment step, particularly in evaluating effects of the reference frame stability in finding final solutions. Comparison between survey results allows us to invert the strain tensor and to compute displacement vectors, the latter when fully constrained solutions are available. The comparisons lead to the conclusion that, during the 1992-1994 period, at least two sources were active. The first was related to a shallow dyke that produced the 1991-1993 eruptive fissures. The second deeper source was depleted during the 1991-1993 eruption and recharged between 1993 and 1994. Local ground movements correlate spatially and temporally with seismic phenomena.