Very shallow earthquakes and brittle deformation in active volcanic areas: The Eatnean region as an example

Abstract

Some aspects of the stress field acting in active volcanic areas were investigated by studying the relationship between surficial seismicity ( h ⩽ 1–2 km) and the brittle deformation pattern of the Etna volcano. The magmatic composition and structural character of Mt. Etna are described, together with its geodynamic regional context, after a discussion of the problem of the state of stress in active volcanoes and a definition of very shallow seismicity. The high level of surficial seismicity, the morphology of the sedimentary basement and the kinematic behaviour of the faults suggest that the eastern flank of Mt. Etna is a shallow seismotectonic domain, structurally decoupled from the rest of the volcanic body. This flank shows a tendency to slide in an eastern direction and is bound to the north by a left-lateral, oblique-slip, normal fault trending E-W, and in the south by an arcuate fault system with right-lateral features (right-lateral, oblique slip normal faults).