In February 1783, Calabria and Sicily were hit by one of the longest seismic crises in our area. It all began on February 5, with a strong earthquake in Calabria, which was followed by many others in the following three years. Some seismic events caused tsunamis which caused considerable casualties and damage.
The Italian coasts are subject to tsunami risk and these historical events prove it.
To find out more, we interviewed Lorenzo Cugliari and Laura Graziani, researchers from the INGV Tsunami Alert Center who described the events of 1783 and some of the activities carried out by the CAT.
Laura, on February 5, 1783, one of the most serious and longest seismic crises of the last two thousand years began in Calabria and Sicily. What happened during that time?
On February 5, 1783, at 12:00, Calabria was hit by a strong earthquake. This event started one of the longest and most disastrous seismic periods in Italian history which lasted more than three years; in fact, the seismic sequence of 1783-84 is among the most important Italian seismic sequences.
In about two months there were five strong earthquakes - on February 5, February 6, February 7, March 1 and March 28, 1783 - which devastated Calabria, between Reggio Calabria and Catanzaro, and part of north-eastern Sicily .
Seismic events have given rise to tsunamis, albeit of different magnitudes. Certainly the most destructive were those of 5 and 6 February.
The earthquakes were then followed, in some cases, by tsunamis. Do historical sources describe this phenomenon?
Yes, it is interesting to read in the documents that have come down to us how the seismic sequence, and the two consequent tsunamis, aroused great interest in the communities of scientists and scholars, both Italian and foreign, who went to the field to make direct observations and document the effects. The result was a vast amount of reports, chronicles, works and maps representing the devastation and which today constitute a valuable source of information, both for the study of this seismic sequence and for the study of the tsunamis associated with it.
Michele Sarconi (1784) and Giovanni Vivenzio (1788) described with particular detail, in their works, the effects caused by tsunamis on the coasts, in particular the effects produced by the tsunami which hit the stretch of Tyrrhenian coast between Scilla and Bagnara on 6 February Calabra.
The first interventions arrived about ten days after the first earthquakes of February; this due to the poor means of communication, the destruction caused by earthquakes which made the few available communication routes unusable, and the controversial figure of King Ferdinand I of Bourbon who proved to be scarcely effective in managing post-earthquake interventions in what would was shortly thereafter Kingdom of the Two Sicilies. Ferdinand of Bourbon, fleeing to Sicily from the papal territories, on 15 February 1783 (ten days after the first earthquake) appointed Count Francesco Pignatelli di Strongoli as vicar general of Calabria, with the task of responding to the primary needs of the territories.
Which areas were most damaged by the earthquakes? What about tsunamis?
The epicenters of the five major earthquakes were located between the provinces of Reggio Calabria (where the seismic sequence began), Vibo Valentia and Catanzaro.
Extensive and widespread damage was caused by the high magnitude of the earthquakes and favored by the poor quality of the artefacts. Contemporary authors describe impressive effects on the environment: changes in the course of rivers, formation of pools of water, large landslides and soil liquefaction effects.
These effects were mainly observed between the plain of Gioia Tauro and Aspromonte, as described in. Historical illustrations portray natural upheavals extended throughout the Calabrian territory from Reggio Calabria to Cosenza (to the north).
As mentioned were those of 5 and 6 February.
On 5 February the sea began to retreat immediately after the earthquake and, subsequently, the tsunami waves hit the provinces of Messina (in particular the locality of Torre Faro) and Reggio Calabria (between Scilla and Cenidio, today Faro Punta Pezzo in the locality Villa San Giovanni) which were flooded three times within 10/15 minutes.
In the reports we read that in some places the sea withdrew leaving the fish aground, in Messina the water flooded the docks of the port destroying them, even the Maritime Theater and the nearby buildings were flooded.
The earthquake of February 6 occurred during the night, was less strong than the previous day's earthquake, caused serious damage to Messina and Scilla and triggered an enormous landslide along the western cliff of Monte Campallà in Scilla. This, falling into the sea, generated a disastrous tsunami.
In Scylla, most of the population, frightened by the tremors of the previous day, had camped on the beach and was surprised by the tsunami waves during the night. About 1500 people lost their lives. The waves subsequently also hit the coasts adjacent to the Strait of Messina.
The area affected by this sequence of phenomena (earthquakes and tsunamis) is not new to such events. Why?
The area that includes Calabria and eastern Sicily is a very seismically active area. In the past it has been affected by numerous strong earthquakes, some of which are capable of generating tsunamis. It is precisely in this area that the most destructive Italian tsunamis occurred, that of 1908, 1905, 1693, as well as those we have just mentioned in 1783, all generated by strong earthquakes.
Lorenzo, the numerous historical tsunamis remind us that there is a seaquake risk for the Italian coasts. Do you think the population is aware of it?
Unfortunately not enough. This emerges from the survey on the perception of tsunami risk, which began in 2018 and reached its third survey in 2021, which allowed us to deepen the various aspects of knowledge of the topic and to understand how much and how the population living in coastal municipalities perceives the tsunami risk.
The results of the survey show a lack of knowledge of tsunamis both as a phenomenon and as a type of risk.
The factors that come into play when we talk about knowledge of a phenomenon like tsunamis are: information, learning and experience. These three aspects are directly connected to the sources through which the individual learns (direct or mediated, institutional or informal) and to experience (direct or indirect).
For this reason, one of the objectives of the research is to collect data that will help to undertake civil protection and tsunami risk communication actions, giving due importance to the communicative language.
We hope that the path taken will lead to a better understanding of the phenomenon and to understanding that even "smaller" tsunamis can pose a risk that cannot be underestimated.
Laura, the INGV Tsunami Warning Center is also engaged in the study of the perception of tsunami risk. What are the populations studied and the main results?
The survey on tsunami risk perception provides methodologically reliable and retraceable statistical data on various issues concerning the population.
The sections that make up the questionnaire place the interviewee in the territorial and socio-demographic context of belonging; this allows us to explore macro and micro issues such as knowledge of the tsunami phenomenon, the contextualized perception of this risk, the social representations connected to the sources of information and the cultural attitudes related to the tsunami risk.
This is the first survey of this type in the reference Euro-Mediterranean context and, due to the size of the sample reached in the last survey, one of the most important community based on the topic internationally.
In three phases of administration of the questionnaire we collected 5.842 telephone interviews and, in the last survey, an adapted version of the questionnaire was administered to a representative sample of the entire national population made up of 1.500 respondents (TelePanel). By choice we decided to administer the questionnaire starting from the regions that have a greater danger from tsunamis: Sicily, Calabria and Puglia, and then move on to Basilicata, Campania, Molise, Lazio and Sardinia.
Summarizing, without wanting to minimize any aspect, the survey outputs have shown that the perception of residents in the coastal municipalities under study is widespreadly low, while the Tyrrhenian and Ionian sides show higher percentages of perception.
Lawrence, finally. Do you envisage activities aimed at citizens to mitigate the tsunami risk?
Certainly. In recent years, much attention has been paid to initiatives involving the direct involvement of citizens, both internationally and nationally.
The Tsunami Alert Center was born as a service closely connected to the Civil Protection activities, for this reason the community is the fulcrum around which the modus operandi of the CAT revolves.
A population aware of the tsunami risk is a population that has acquired the correct information and knowledge through a multidisciplinary process and is able to independently implement them in an emergency situation. In this regard, the CAT is engaged, in coordination with the national Civil Protection Department, in the development of strategies that implement the last-mile (last-mile strategies) not only from the technological point of view for the dissemination of the alert to citizens, but from the point of view of the preparation of the same who, through repeated training and information activities, decode the alert message by adopting appropriate behaviours.
First among the initiatives that directly involve citizens in the tsunami risk mitigation process is Tsunami Ready. A program, born under the aegis of UNESCO, aimed at promoting the preparation of coastal communities for tsunami risk as an active collaboration between government organizations for emergency management, local administrations and citizens. The program envisages the voluntary involvement of the coastal Municipalities, which, through the achievement of 12 indicators, will lead the Municipality to obtain recognition from UNESCO as a Tsunami Ready community.
For further information – Link to the article on the INGVterremoti Blog