Comment on the article “Propagation of a lithospheric tear fault (STEP) through the western boundary of the Calabrian accretionary wedge offshore eastern Sicily (Southern Italy)” by Gallais et al., 2013 Tectonophysics

The oceanic lithosphere of the Ionian Sea is subducted under the Calabrian Arc, and it has been proposed that the Ionian lithosphere has been torn apart (STEP fault sensu Govers and Wortel, 2005) on its western side, close to the Malta escarpment, a major morphological feature inherited from the Mesozoic palaeogeography. In a recent paper Gallais et al. (Tectonophysics, 2013) have traced a right-lateral strike-slip fault that extends from south of the Alfeo Seamount all the way to the Tyrrhenian Sea. They also argue that the position of the STEP fault is distinct from, and located ca. 50 km east of, the Malta escarpment. Gallais et al. document with some additional details a fault segment that was already reported in the literature and that is located south of the Alfeo Seamount. However, Gallais et al. have little constraints to trace the STEP fault further to the north; in this sector a belt of surface deformation that can be related to the STEP fault has been mapped from a denser grid of seismic profiles, and is located west-ward, close to the Malta escarpment (Argnani and Bonazzi, 2005).This undermines the conclusion of Gallais et al. that the lithospheric tear is distinct from the Malta escarpment. It is therefore likely that surface deformation associated with the lithospheric tear fault is more complex and is not represented by a single strike-slip fault.