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The Red Alert Level (Watch) indicates that the coasts of one or more regions may be affected by a tidal wave with a height of more than 0.5 metres in open sea and/or a run-up (R) of more than 1 m, i.e. that the flood may exceed the topographic height of one metre above sea level.

When the tidal wave has these characteristics, there is a real danger not only for the people closest to the coast but also for anyone who is in areas which are not much above sea level.

In order to calculate the areas which may be flooded, reference is made to a probabilistic estimate of the maximum expected height of the wave, which is described in the document issued by the Head of the Civil Protection Department in 2018.

To better understand the meaning of the Red Alert (watch) we must remember two things: the first is that even a wave of a single metre can generate dangerous floods, able to go hundreds of metres inland, and strong currents which can drag even adults into the sea. The second is that the Red Alert (Watch) can announce the arrival of much higher and more dangerous waves, and that these can continue for several hours after the initial wave.

When a Red Alert Message (Watch) is issued, it is necessary to immediately move away from coastal areas lower than sea level, moving in an orderly but fast manner to higher places. The areas to be evacuated will be indicated in the municipal emergency plans, and are currently available for some regions on the website. Evacuation must be carried out in all regions indicated in the message.

For the definition of the thresholds of the alert levels according to the magnitude, the depth and the distance from the epicentre, see the Decision Matrix table.