Reconciling deep seismogenic and shallow active faults through analogue modelling: the case of the Messina Straits (southern Italy)

The catastrophic 28 December 1908, M-w 7.1, Messina Straits earthquake was generated by a large, low-angle, SE-dipping, blind normal fault. A number of shallow, high-angle normal faults arranged in a graben-like fashion occur in the same area both on land and offshore, reaching the surface and in some instances affecting recent deposits. These faults are normally interpreted as active and have often been considered potentially seismogenic. We used an analogue modelling approach to simulate the evolution of a large, low-angle normal fault and investigate its relationships with the overlying secondary faults. We find that these faults represent the brittle surface expression of the long-term activity of the underlying master fault, and that all faults mapped by previous workers in the Messina Straits are compatible with sustained slip along the fault responsible for the 1908 earthquake. Our results confirm that analogue modelling provides a useful tool to investigate the evolution and the hierarchical relationships of fault systems, suggesting that this approach is effective in the investigation of complex seismogenic areas.