Sicily and Southern Calabria focal mechanism database: a valuable tool for local and regional stress field determination

Abstract

In this paper, we present a new catalogue of focal mechanisms calculated for earthquakes recorded in Sicily and southern Calabria; it comprises about 300 solutions, for events with a magnitude ranging between 2.7 and 4.8, occurring between 1999 and 2011. We used P-wave polarities to compute the fault plane solutions . Two main goals were achieved: the first is that the catalogue allowed depicting the stress regime and kinematics characterizing the studied area at a regional and more local scale. In particular, moving along the tectonic lineament extending from the Aeolian Islands to the Ionian Sea, we observed a change between a regime characterised by sub-horizontal P-axes, ca. NW-SE directed, to an extensive one in the Calabro-Peloritan Arc, where T-axes striking in NW-SE direction prevail. Our results also show that part of the seismicity is clustered along main active seismogenic structures, of which the focal mechanisms indicate the kinematics. Finally, in the Etna volcano area, we found different stress fields acting at different depths, due to the combination of the regional tectonics, the strong pressurization of the deep magmatic system and the dynamics of the shallower portion of the volcano. As a second outcome, we highlight that the catalogue also represents a valuable tool, by the data distribution on the internet, for further studies directed toward improving the understanding of the geodynamic complexity of the region and for a better characterization of the seismogenic sources.