1693, Sicily earthquake, the most powerful in Italy
This earthquake has 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.
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 has 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 has died. 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 the 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 up on our legs, or in one place on the dancing Earth; nay, those that lay along on the ground were tossing from side to side, as if on a rolling billow.”
January 9 foreshock
A destructive earthquake occurred two days before the mainshock at 21:00 local time, centered in the Val di Noto. It had an estimated magnitude of 6.2 and a maximum perceived intensity of VIII–XI on the Mercalli intensity scale. Intensities of VIII or higher estimated for Augusta, Avola Vecchia, Floridia, Melilli, Noto Antica, Catania, Francofonte, Lentini, Scicli, Sortino and Vizzini. Augusta lies well outside the main zone of severe shaking; its extensive damage is probably due to its construction on unconsolidated sediments.
January 11 mainshock
The earthquake lasted for four minutes, according to contemporary accounts. The estimated magnitude of 7.4 is taken from the extent. A degree of the recorded damage, with a very large area that reached more on the Mercalli scale. The maximum shaking reached XI in the towns of Buscemi, Florida, Melilli, Occhiola, and Sortino.
The tsunami triggered by the earthquake affected most of the Ionian Sea coast of Sicily, about 230 kilometres in all. Meanwhile, the first thing that was noted at all localities affected was a withdrawal of the sea. The strongest effects have concentrated around Augusta. The initial withdrawal left the harbor dry, followed by a wave of at least 2.4 metres in height. A possibly as much as 8 metres, that inundated part of the town. The maximum inundation of about 1.5 kilometres was recorded at Mascali.