The 1693 Sicily earthquake struck parts of southern Italy near Sicily, Calabria, and Malta on January 11 at around 21:00 local time. This earthquake was preceded by a damaging foreshock on January 9. The main quake had an estimated magnitude of 7.4 on the moment magnitude scale, the most powerful in Italian recorded history, and a maximum intensity of XI (Extreme) on the Mercalli intensity scale, destroying at least 70 towns and cities, seriously affecting an area of 5,600 square kilometres (2,200 sq mi) and causing the death of about 60,000 people. The earthquake was followed by tsunamis that devastated the coastal villages on the Ionian Sea and in the Straits of Messina. Almost two-thirds of the entire population of Catania were killed. The epicentre of the disaster was probably close to the coast, possibly offshore, although the exact position remains unknown. The extent and degree of destruction caused by the earthquake resulted in extensive rebuilding of the towns and cities of southeastern Sicily, particularly the Val di Noto, in a homogeneous late Baroque style, described as "the culmination and final flowering of Baroque art in Europe".
According to a contemporary account of the earthquake by Vincentius Bonajutus, published in the Philosophical Transactions of the Royal Society, "It was in this country impossible to keep upon our legs, or in one place on the dancing Earth; nay, those that lay along on the ground, were tossed from side to side, as if on a rolling billow."
Sicily lies on part of the complex convergent boundary where the African Plate is subducting beneath the Eurasian Plate. This subduction zone is responsible for the formation of the stratovolcanoMount Etna and considerable seismic activity. Most damaging earthquakes however, occur on the Siculo-Calabrian rift zone. This zone of extensional faulting runs for about 370 kilometres (230 mi), forming three main segments through Calabria, along the east coast of Sicily and immediately offshore, and finally forming the southeastern margin of the Hyblaean Plateau. Faults in the Calabrian segment were responsible for the 1783 Calabrian earthquakes sequence.
In the southern part of the eastern coast of Sicily, investigations have identified a series of active normal faults, dipping to the east. Most of these lie offshore and some control basins that contain large thicknesses of Quaternary sediments. The two largest faults, known as the western and eastern master faults, border half-grabens with fills of up to 700 metres (2,300 ft) and 800 metres (2,600 ft) respectively. Onshore, two ages of faulting have been recognised, an earlier phase trending NW-SE and a later phase trending SSW-NNE that clearly offsets the first group, including the Avola fault and the Rosolini-Ispica fault system.