Predicting an earthquake is still impossible, but if we can accurately understand the mechanisms behind earthquakes, then it will become easier to protect ourselves and avoid the worst damage.
More than 113 years after the most devastating European earthquake in terms of human lives, science seems to have finally found an answer, identifying the “smoking gun” at the origin of the Messina Strait disaster of 28 December 1908. The earthquake, which reached magnitude 7.1 on the Richter scale, it has been the strongest in Europe since instrumental measurements have existed.
Europe had already witnessed at least two destructive earthquakes, but their magnitude could not be estimated instrumentally: the great earthquake that devastated Catania, Syracuse and Noto, in eastern Sicily on 11 January 1693 – the official statistics of the time reported 54,000 victims. Later, the 1755 Lisbon (Portugal) earthquake caused even greater clamor, originating from the movement of a large fault in the Atlantic Ocean. The deadly coupled earthquake-tsunami, on the morning of All Saints, killed tens of thousands of victims in the capital of Portugal.
CultureApocalypse in Messina, the most dramatic earthquake in the history of Italy
The structure of the Earth and the motions of the mantle, highlighted by the arrows. The arrows indicate the direction of motion of the mantle, which cools near the crust and partly exits the oceanic ridges and partly returns to the depths. The movement raises and lowers the oceanic crust by up to 2 kilometers. To learn more: what is the velocity of magma in the Earth’s mantle?
But the Messina earthquake of 1908 is undoubtedly a milestone in European history, as it happened when seismology was beginning to take its first steps. It was thus possible to measure the magnitude, in addition to the intensity of the earthquake – corresponding to the XI degree of the Mercalli scale, equivalent to almost absolute destruction. Again, the earthquake was followed by a tsunami that overwhelmed the citizens who had managed to escape the collapses. The tragic accounting of the victims reached 100,000 lives lost on that cold December morning.
The national and international scientific community, in over a century of studies, has tried to locate the fault responsible for the shaking, without however reaching a certain answer. But now a study published in Earth-Science Reviewsseems to have finally solved the mystery. The publication, the result of an international collaboration between the universities of Catania and Kiel (Germany) and the Etneo Observatory of the National Institute of Geophysics and Volcanology , documents the outcome of a campaign of observations based on a series of geophysical prospects for very high resolution (which provided a sort of ultrasound of the seabed of the Strait), on the analysis of seismological data and on the study of the dislocations of ancient Quaternary marine terraces (from the Quaternary , the most recent geological period).
The research highlights the great geodynamic complexity of the Strait of Messina, a depression that follows a very elongated S-shaped path, with a width varying between 3 and 16 km and 40 km in length. The depression, which began to form from the Middle Pleistocene , is located at the core of an active subduction zone, where the Ionian oceanic lithosphere subducts under the European continent.
«The study is of considerable importance because, for the first time, it reveals the location and geometric characteristics of the fault that at the first light of 28 December 1908 caused the most serious seismic catastrophe in Europe. The fault has a length of 34.5 km and is potentially capable of triggering earthquakes of a magnitude close to 7, an energy very similar to the one released more than 100 years ago “, says Giovanni Barreca, first author of the article on Earth -Science Reviews.i
The deep rift along the Strait of Messina, revealed by ultrasound techniques, shows evidence of recent activity, with seabed unevenness with escarpments up to 80 meters high. At Messina the fault deviates sharply in the Calabrian hinterland, along the course of the Catona river ( see illustration above ). “The discovery has significant implications for the populations bordering the Strait of Messina: knowing where the fault is located will allow in the future to be able to reduce the risk through monitoring with modern technology such as fiber optic cables already used experimentally by our group research off the coast of Catania and Syracuse ”, concludes Barreca.
