Are you prepared? - Tsunami risk


Sei preparato Rischio Maremoto

Learning how to prevent and reduce the effects of tsunamis is a responsibility that concerns everyone. Share your knowledge with your family, school, friends and colleagues: spread information about tsunami risk is a collective responsibility for all of us.

What is a tsunami?
A seaquake, tsunami in Japanese, is a series of waves produced by the rapid displacement of a large mass of water. In open water, the waves propagate very quickly over large distances, with an almost imperceptible height (at times less than one meter) but the wavelength (the distance between one wave and the next) can be tens of kilometers. As the wave approaches the coast, its speed decreases while its height increases rapidly, even by tens of meters. The first wave may not be the largest, and several minutes may pass between the arrival of one wave and the next one.

What causes a tsunami?
It is generally caused by strong earthquakes with epicenter at sea or near the coast. Tsunamis can also be generated by submarine or coastal landslides, by volcanic activity in the sea or near the coast and, much more rarely, from meteorites that fall into the sea.

Is Italy exposed to tsunami risk?
All the Mediterranean coasts are exposed to tsunami risk, due to the high seismicity and to the presence of numerous active volcanoes, both emerged and submerged. Over the past thousand years, dozens of tsunamis have been documented along the Italian coasts – only some of which destructive. Eastern Sicily, Calabria, Puglia and the Aeolian archipelago are the most affected coastal areas. However, minor tsunamis have also been registered along Liguria coasts, and in the Tyrrhenian and Adriatic seas. We must also consider that the Italian coasts can be reached by tsunamis generated in areas of the Mediterranean far away from our country.

What happens along the coasts?
A tsunami appears as a rapid rise in sea level or a wall of water that hits the coast, causing a flood. Sometimes we observe an initial and sudden retreat of the sea, which leaves dry ports and beaches. Tsunami waves have much more strength than sea storms and can penetrate hundreds of meters inland (and, if the coast is very low, even kilometers), dragging everything in their path: vehicles, boats, trees, tanks and other materials, which increase their destructive potential.

When will the next tsunami occur?
It is not possible to predict: it can occur at any time. We know many things about tsunamis, but it is not yet possible to predict when and where they will occur.

Is there an Italian alert system?

In 2017, the SiAM - Sistema di Allertamento Nazionale per i Maremoti Generati da Sisma was instituted in Italy. Three organizations cooperate in this system: the Ingv - National Institute of Geophysics and Volcanology, which operates through the Cat - Tsunami Warning Center; Ispra - Superior Institute for Environmental Protection and Research; and the Department of Civil Protection.
The Ingv's Cat assesses the possibility that an earthquake with an epicenter at sea or near the coast could trigger a tsunami. On the basis of these assessments, the Civil Protection Department broadcasts alert messages with the aim of activating, as quickly as possible, the National Civil Protection Service and informing the population. Finally, the maritime data provided by Ispra allows for the confirmation or non-confirmation of a possible tsunami.
SiAM is part of the international warning system that was established in the Mediterranean on the model of those active in the Caribbean Sea and the Pacific and Indian oceans. Compared to these, however, it has limitations because in a shallow sea like the Mediterranean, wave arrival times are very short, which reduces the possibility of alerting the population. It is therefore important to be well aware of the rules of conduct, while remembering that tsunami risk inevitably involves false alarms.

What to do to reduce the risk?

The use of monitoring networks, the study of past events and of wave propagation models are just a few of the actions that allow to reduce the tsunami risk. Such knowledge contribute to improve territorial planning and to carry out interventions to make areas exposed to the risk safer, and also to elaborate emergency plans.
Being aware and being prepared are the best ways to prevent and reduce the consequences of a tsunami.

What to know

In a shallow sea as the Mediterranean, wave arrival times are very short. Authorities may not have time to issue an alert. So if you live, work or travel in a coastal area it is even more important to recognize phenomena that may indicate the arrival of a tsunami:

  • a strong earthquake you have felt or heard about
  • a deep and increasing noise coming from the sea, like that of a train or a low flying aircraft
  • a sudden and unusual retreat of the sea, a rapid rise in sea level or a big wave extended over the whole horizon

Remember that houses and buildings close to the coast aren’t always safe.

  • the degree of safety of a building depends on various factors, for example the typology and quality of materials used, the altitude, the distance from the shore, the number of floors, the degree to which it is exposed to the impact of the wave
  • generally, the highest floors of a concrete reinforced building, if properly built, offer adequate protection.

It is important to know the environment you live, work or stay in to better prepare for an emergency:

  • ask local Civil Protection officials about the municipal emergency plan, dangerous areas, evacuation routes and times, signals to follow and waiting areas to reach in case of emergency;
  • be informed about the safety of your home and the places surrounding it;
  • be sure that your school or workplace has an evacuation plan and that regular drills are held;
  • prepare for the emergency with your family and have a plan on how to reach escape routes and waiting areas;
  • have a first-aid kit and supplies of food and water ready at home.
  • learn the correct behavior to adopt during and after a tsunami.



During a tsunami

If you are at the beach or in a coastal area and receive an alert message that indicated the possible arrival of a tsunami wave, or recognize at least one of these phenomena:

  • a strong earthquake you have felt yourself or that you have heard about
  • a sudden and unusual retreat of the sea, a rapid rise in sea level or a big wave extending across the whole horizon
  • a deep and increasing noise coming from the sea, like that of a train or a low flying aircraft

Move away from the water and quickly reach the nearest elevated area (such as a hill or the upper floors of a building). Warn those around you of imminent danger.

Run following the fastest escape route. Do not go by car, it could become a trap.

If you are at sea, you may not be aware of the phenomena accompanying the arrival of a tsunami, so it is important to always listen to the radio:

If you are in a boat and you get news of an earthquake on the coast or at sea, move further offshore.

If you are in a port, leave the boat in port and move to safety in a higher place.

What to do after a tsunami

Stay in the area you have reached and discourage anyone from going back to the coast: the first wave might be followed by more dangerous ones.

Check the health conditions of the people around you and, if possible, give first aid assistance.

Listen to the authorities to find out when it’s safe to leave and what you need to do.

Use the phone only for emergencies.

Do not drink tap water.

Do not eat foods that have come into contact with the water and materials transported by the tsunami: they may be contaminated.

If your home has been affected by the tsunami, do not return without permission.

A tsunami can be generated by an earthquake or volcanic activity: be informed, therefore, about what to do in case of an earthquake or eruption