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Breadcrumbs (EN)

The methods and procedures for assessing earthquakes and the associated potential tsunamis and for managing and sending alert messages are particularly complex and difficult, not least because of the uncertainty which characterises the estimates and the extreme urgency of obtaining scientific data as quickly as possible.

It should be remembered that a given seismic event does not always evolve into an actual tsunami, even if the magnitude, depth and location are compatible with generating a tsunami. Given the current state of knowledge, it is in fact impossible to know exactly and within the time required for issuing the alert what the extent of the vertical displacement of the fault is and the length of the stretch concerned, and therefore the volume of the displaced water mass.

Despite the enormous scientific and technological progress, there is room for error in the probabilistic assessments of the timing, intensity and location of the impacts, which translates into the possibility of false alarms or that the phenomena should also be much more intense than initially expected, for example in the event that an earthquake - however modest - should trigger an underwater landslide, thus amplifying the effects of the earthquake itself and the height of the tsunami waves.

Moreover, the impact of the tsunami on the coast does not depend only on the magnitude of the seismic source and on its distance from the coast, but also on the shape of the seabed and the geometry of the coastline, which can lead to very different effects even on nearby stretches of coast, which locally can become particularly intense and dangerous (for example in narrow and long bays).

The need to provide timely information on potentially catastrophic events, allowing citizens and authorities to immediately take all necessary actions to mitigate the impact of the tsunami involves the need to find a reasonable compromise between the accuracy of the estimate and the timeliness of sending messages to the population: waiting until the last moment to have an accurate assessment, in fact, may compromise the ability to take protective measures in good time.

It is for this reason that shift workers and the CAT-INGV officials must be adequately trained, pass specific examinations to assess the skills and knowledge acquired, and continuously monitor earthquakes potentially capable of generating tsunamis even outside their jurisdiction area.