1908 Messina earthquake

A devastating earthquake occurred on 28 December 1908 in Sicily and Calabria, southern Italy, with a moment magnitude of 7.1 and a maximum Mercalli intensity of XI (Extreme). The epicentre was in the Strait of Messina which separates Sicily from the Italian mainland. The cities of Messina and Reggio Calabria were nearly destroyed and around 120,000 people died, making it the deadliest earthquake in the history of Europe.

According to Italy's National Institute of Geophysics and Vulcanology, the earthquake was caused by a large, low-angle SE-dipping, blind normal fault, lying mainly offshore in the Strait of Messina, between plates. Its upper projection intersects the Earth's surface on the western, Sicilian side of the Strait. In 2019 researchers at Birkbeck, University of London, discovered the active fault responsible for the earthquake. The study, led by Marco Meschis, identified the fault as the previously mapped but little-studied Messina-Taormina Fault which lies off the Sicilian coast and runs the length of the Strait of Messina. The team used data from 1907–1908 to examine the pattern of uplifts and subsidence observed in the Messina and Calabria area which bore a strong resemblance to those resulting from other powerful earthquakes triggered by normal faults. After comparing the direction and size of movements on well-known faults with the surface movements seen in Messina and Calabria, the researchers identified the probable active fault which caused the catastrophic earthquake as well as the direction and size of the movements.

Italy sits along the boundary zone of the African plate, and this plate is pushing against the sea floor underneath Europe at a rate of 25 millimetres (0.98 inches) per year. This causes vertical displacement, which can cause earthquakes. The earthquake was recorded by 110 seismographic stations around the world, and was one of the first to be recorded by instruments.

The Strait of Messina is part of the regional tectonic feature known as the Calabrian Arc, an area of differential uplift deriving from the dynamics of the Ionian and South Tyrrhenian tectonic units, two of the lithosphere blocks of microplates recognized in the highly fragmented Italian portion of the Africa-Eurasia contact. Some of the strongest earthquakes of the last centuries occurred in the Calabrian Arc, such as the 1783 and 1905 Calabrian earthquakes, as well as the more catastrophic 1908 Messina earthquake.

Records indicate that considerable seismic activity occurred in the areas around the Strait of Messina for several months prior to 28 December; it increased in intensity beginning on 1 November. On 10 December, a magnitude 4 earthquake caused damage to a few buildings in Novara di Sicilia and Montalbano Elicona, both in the Province of Messina.

A total of 293 aftershocks took place between 28 December 1908 and 11 March 1909.

In 2008, it was proposed that the concurrent tsunami was not generated by the earthquake, but rather by a large undersea landslide it had triggered. The probable source of the tsunami was off Giardini Naxos (40 km south of Messina), on the Sicilian coast, where a large submarine landslide body with a headwall scarp was visible on a bathymetric map of the Ionian seafloor. Another study attributed the source of the tsunami to having been a landslide which took place off of north-eastern Sicily and southern Calabria, most likely offshore between San Leo and Bocale in Calabria.

On Monday, 28 December 1908, at 5:20:27 an earthquake of 7.1 on the moment magnitude scale occurred. Its epicentre was in the Strait of Messina which separates the busy Sicilian port city of Messina from Reggio Calabria on the Italian mainland. Its precise epicentre has been pinpointed in the northern Ionian Sea area close to the narrowest section of the Strait, the location of Messina. It had a depth of around 9 km (5.6 mi).