In Italy, seismic activity has left deep traces over time and, unfortunately, continues to affect towns and populations. Knowledge of past earthquakes makes it possible to evaluate the seismic hazard of certain areas, allowing for the elaboration of defense and protection strategies. And it is not to forget that we spoke to Dante Mariotti about the terrible earthquake - tidal wave that hit Sicily and Calabria on December 28, 1908. An INGV researcher since 2007, Dante deals with studies of historical seismology and volcanology and collaborated in the creation of the Catalog of Strong Earthquakes, the analytical tool that provides all the information available for each earthquake in an easily accessible format, allowing the smallest details of the impacts on the territory.
The earthquake that struck the shores of the Strait of Messina in 1908 can be considered one of the greatest catastrophes that the Italian state had to face. What happened at dawn on that December 28th?
The earthquake of 28 December 1908 was one of the strongest in Italian seismic history, a real catastrophe. Known by the name with which it is now defined from the point of view of the effects both for the very high number of deaths and for the destruction of two important cities such as Reggio Calabria and Messina. The shock was recorded at 05:20:27 with a magnitude value of 7.1 and lasted about forty seconds. Over seventy localities in the province of Reggio Calabria and fourteen in the province of Messina suffered devastating destruction, extending from 70 to 100% of the building. In Messina the earthquake completely destroyed the urban fabric: homes, civil and ecclesiastical public buildings, infrastructures. According to data from the Ministry of Public Works, only two houses were unharmed, the others collapsed completely or only the external walls remained standing, while roofs, attics, partition walls and stairs collapsed. It must be said that the damages of this earthquake overlapped in many cases those of the seismic events of 1894, 1905 and 1907. No adequate repairs had been carried out and the disaster was caused not only by the great violence of the earthquake but also by structural weakness of the building industry, both in the cities of major centers and in rural villages.
Following the earthquake, a tsunami hit both coasts of the Strait. What was the extent of the tidal wave?
According to witnesses, the tsunami occurred five to ten minutes after the earthquake. It was also of extraordinary violence and probably, at least in historical times, the most important found in Italy. It struck both coasts of the Strait of Messina and aggravated the destruction of the earthquake in various locations, causing other victims among the people who had escaped the collapses. On the eastern coast of Sicily, the height reached by the waves was between six and nine and a half meters and was measured in the stretch between the mouth of the Portalegni river, south of the port of Messina, and Giardini Naxos, with an extreme point of over eleven meters in Sant'Alessio Siculo. As far as Calabria is concerned, the tsunami was more serious in the stretch from Gallico Marina to Lazzaro and the maximum height of the waves was between six and eleven metres, with a maximum of about thirteen meters south of the town of Pellaro. To the north of this area, the tsunami was still significant on the Reggio coast of the Strait up to Punta Pezzo, while it was much smaller along the Tyrrhenian coast of Calabria.
And the impact of events on man and the environment?
As far as deaths are concerned, the most reliable estimate for the whole affected area is around eighty thousand dead. The victims were therefore very numerous, there were heavy social repercussions also due to the severely damaged building heritage. The earthquake - tidal wave aggravated the isolation of some areas and there were repercussions for decades. The impact of the catastrophic event on the environment led to major upheavals that marked the landscape, especially in the area of the Strait where the upheaval was greater. Land subsidence was recorded in Messina, Reggio Calabria and Villa San Giovanni. Considerable variations of the coastline were found in numerous Calabrian localities, where the earthquake and tsunami accelerated a phase of immersion of the coast already in progress. At Pellaro the coast retreated in some points by about fifty meters while at Gallico Marina the beach lost ten meters in width. Finally, a large area of Calabria and Sicily suffered landslides, mudslides and landslides triggered by the earthquake with partial displacements and landslides.
The disastrous earthquake - tidal wave has been reconstructed thanks to precious scientific sources. Which?
As far as scientific sources are concerned, some of the greatest Earth science scholars dealt with the earthquake and produced hundreds of works that investigated the event from various disciplinary points of view, from the methods of propagation of seismic waves, to the analysis of the geological aspects, to the effects in the engineering field. The most detailed investigations on the effects were conducted by three illustrious scientists: the abbot Giuseppe Mercalli, who gave his name to the well-known intensity scale for classifying the effects of earthquakes; Mario Baratta, founder of Italian historical seismology; Giovanni Platania, professor of terrestrial physics at the University of Catania, who thoroughly studied the effects of the tsunami. Mario Baratta was the author of the most complete and authoritative work for knowing the 1908 earthquake from direct observations. His great work, La catastrofe seismica calabro messinese (1910), is a methodological point of reference in the field of seismology studies and still today it commands the attention of scholars for the quality and systematic nature of the information, combined with a great clarity of exposition, motivated by the intention of divulging that data as much as possible. Baratta carried out two missions to the places devastated by the earthquake and subsequently worked for about a year on organizing the data collected, also making use of numerous reports from mayors, parish priests and other authorities in the affected areas. Giuseppe Mercalli also visited in April 1909 Messina, Reggio and other affected Calabrian localities. He drew up a report full of observations, he elaborated a list of places classified with degrees of intensity, using his macroseismic scale, to which on this occasion, faced with the immense dimensions of the destruction, he added the degree XI "catastrophe". As regards the tsunami that hit the banks of the Strait, the most important information on the effects was collected by Giovanni Platania who disclosed it in a study published in the Bulletin of the Italian Seismological Society. The author visited all the affected sites on the eastern coast of Sicily and some of the most devastated localities on the Calabrian coast, collecting the accounts of direct witnesses of the incident and estimating the height reached by the waves by measuring the marks left on the walls and on the terrain through the use of precise optical instruments.
What about historical sources?
The most reliable historical sources are administrative sources and institutional documentation. conserved in particular in the state archives of Messina and Reggio Calabria. The central state archive is also an important source of information. It is necessary to point out the extensive report of the General Directorate of Special Services of the Ministry of Public Works of 1912, published at the end of the emergency phase, which traces the final balance of the activity carried out by the government in the affected municipalities for the safety of unsafe buildings and for the construction of barracks for the homeless and public offices left without site. Attached to this report is a detailed summary table of the damages and victims relating to all the municipalities in the most affected provinces. Equally relevant for the analysis of the effects is a vast photographic documentation, the result of the many Italian and foreign photographers who went to the site. The most important contribution from this point of view is a publication by the Italian Photographic Society which put together over six hundred photographs that document in a realistic and effective way the "before" and "after" of the cities of Messina, Reggio and many towns in the Calabria. Conceived at the time as a means of transmitting the memory of the original appearance of the localities and monumental buildings destroyed by the earthquake, this collection is today an extraordinary tool for studying the effects of earthquakes and tsunamis on towns and buildings. There are also some very rare cinematographic footage documenting the damages of the destructive event and the extreme emergency situation in which the populations found themselves immediately after the catastrophe.
6) Why is it so important to keep the memory of events like this alive?
Natural events continue to cause loss of life and economic resources and this should not happen in a country like Italy where the tradition of scientific research in the field of earth sciences is excellent. Continuing to research historical earthquakes and disseminating the results obtained helps to improve seismic hazard and vulnerability study maps, thus promoting the technical ability to defend against earthquakes. When it comes to defense against the destruction caused by events, individual responsibility must also come into play: we must be the first to worry about our safety, delegating the skills to the experts but not the awareness of the risks to which we are exposed. We need to build a culture of safety that is not only academic but popular, belonging to the people. This is why it is so important to keep the memory of past events alive.
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