Buried active faults in the Zafferana Etnea territory (south-eastern flank of Mt. Etna): geometry and kinematics by earthquake relocation and focal mechanisms

Abstract

We relocated seismicity that occurred from 2000 to 2005 inside a sector of Mt. Etna, comprising the town of Zafferana Etnea, using the double-difference technique. This approach revealed some spatial clusters of events at depths of 3.0 km to 5.5 km b.s.l., which suggested NE-SW-oriented and NNW-SSE-oriented active structures located west and north-west with respect to Zafferana Etnea. We also calculated 64 fault plane solutions, and azimuth and dip distributions of maximum compression P axes. The data include eight events with magnitudes between 3.1 and 3.7 that caused damage to Zafferana Etnea. This approach has allowed the definition of the geometry of structures that show no surface evidence, but are potentially hazardous for this territory. These faults might be linked to the regional tectonics, although they were activated by stress changes related to a general pressurizing of the Mt. Etna magma system between 2000 and 2005.