Geodynamic implications of new geodetic measurements in the Messina Straits Area

Abstract

Th Messina Straits (southern Italy) on December 28, 1908 was struck by a Ms=7.5, seismic event, that was the largest earthquake occurred in Italy during the last 100 years. The earthquake and the related tsunami caused thousands of victims and severe destruction in a wide area along the Sicilian and Calabrian coasts. After that time many geophysical and geological studies were developed to evaluate the seismic characteristics of the 1908 earthquake, the seismic risk and the geological evolution of the region in the framework of the Mediterranean geodynamics, characterized by the collision between the African and Eurasian plates. With the aim to evaluate the present crustal motion of this area, that undergone a recent tectonic evolution that produced an important uplift during the last 125 Kyears, since 1970 was started a geodetic research. A geodetic network was set up across the Straits and repeatedly measured with terrestrial techniques till 1980. In 1987, a 7 vertices network (4 vertices in common with the already existent network) was surveyed for the first time by the GPS space technique, improving the accuracy of the coordinate determinations. Finally, in 1994 a wider network was established and surveyed again to collect additional GPS observations about a larger area across the Straits. In this paper we provide a general geophysical description of the Area and the results obtained by the analysis of two GPS surveys (1987 and 1994) with respect to those achieved by the terrestrial surveys (from 1970 to 1980). Our analysis leads to exclude the occurrence of significant crustal horizontal deformations across the Straits in ha last 15 years; this conclusion is in agreement with current geophysical models that exclude any aseismic deformations acting in this area.