There are two alert levels for the SiAM (National Seaquake Alert System), the Advisory level (Orange Alert) and the Watch level (Red Alert) which are consistent with the national Civil Protection legislation and are defined on the basis of a decision matrix approved by the international tsunami monitoring and alert bodies. For full information purposes, the Information message should be added to these two alert levels; this is not an alert level, but should be considered as a message sent for appropriate information purposes, after an earthquake of magnitude equal to or greater than 5.5, to the subjects of the national civil protection system identified in the annexes attached to the SiAM directive and to the other Countries of the Euro-Mediterranean area which have signed up to the CAT-INGV services.
Each of the two alert levels must be associated with a flood area, which could be reached by the tsunami and must therefore be evacuated before the arrival of the first wave, according to the emergency plans developed by the municipalities.
As regards Italy, the coastal areas which could be flooded have been determined with a criterion based on the estimated hazard for the various zones. Details of this procedure are given in the "Indications for... emergency plans..." and in the document attached to the latter, drawn up by the INGV. The definition of the contours of the evacuation zones is currently based on the results of the TSUMAPS-NEAM project, funded by the E.U. and coordinated by the INGV which estimated for the first time the tsunami hazard for the whole NEAMTWS area. On the basis of this hazard model, which was determined on a probabilistic basis and limited to tsunamis of seismic origin, the Civil Protection Department established the level of protection to be adopted by the evacuation areas, as described in the cited document.
The maps are available on the ISPRA website for nearly all of the most dangerous regions in Italy, and will soon be available for all coastal areas. This information has a twofold objective: to prepare municipal emergency plans for the risk of a tsunami, identifying escape routes and safe areas to be reached in the event of an alert, and to inform citizens whether they are inside or outside the evacuation zone for each alert level.