The Strait of Messina Fault is a normal fault system running along the narrow channel that separates the island of Sicily from the toe of the Italian mainland in Calabria. It is part of the extensional tectonics tearing apart southern Italy, where the crust is being pulled open and the strait itself is a subsiding graben bounded by active faults.
Because the fault lies directly beneath a densely populated strait, its ruptures threaten the cities of Messina and Reggio Calabria on opposite shores. Normal faulting here can also displace the sea floor and trigger tsunamis, adding a second hazard to the already violent ground shaking.
The 1908 Messina earthquake (magnitude ~7.1) is among the deadliest in European history, killing an estimated 80,000 people or more when it flattened both cities. A tsunami with waves several metres high struck moments after the shock, drowning survivors along the coast and cementing the strait's reputation as one of Italy's most dangerous seismic zones.