Link between major flank slip and 2002–2003 eruption at Mt. Etna (Italy)

Abstract

The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake‐induced surface rupture (sinistral offset ∼0.48 m) occurred along the E‐W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further (∼0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW‐SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (<4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESE‐WNW extension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three‐stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation).