Geophysical and geological evidence of a previously undetected NW-trending fault crossing the historical centre of Messina (Sicily, south Italy)

Extensive ambient noise measurements have been carried out in the historical centre of Messina (Sicily, South Italy) and the related HVSR results showed a clear variation of the fundamental peak frequency in the range between 0.4 Hz and 1.6 Hz. This frequency variation is detected across a NW-SE segment, and it can be imputed to a strong lateral heterogeneity of the sediment cover going from southwest to northeast of the study area. Moreover, we carried out a detailed geological field survey and analysis of land surface morphology based on topographic maps and DTM data that allowed us to detect the NW-trending fault, never documented in literature, crossing the historical centre of Messina. Geologic observations indicate clearly normal faulting and activity of this fault is documented at least until Middle Pleistocene, with likely prosecution during Upper Pleistocene.

The detected NW-trending fault is roughly perpendicular to the strike of the main structural system of the Straits of Messina framework to which the major earthquake of 1908 (M 7.1) is imputed. Therefore, deeper future investigations for appropriate framing into the local geodynamic context and for evaluation of its eventual prosecution in the offshore area are necessary.

In this preliminary study we identify structural discontinuities and faults which may represent new sources of hazard in a town exposed to very high seismic risk in Italy.