Some reflections on tsunami Early Warning Systems and their impact, with a look at the NEAMTWS

This paper discusses some features of Early Warning Systems (EWSs), with a particular focus on those dealing with tsunamis. First, a description is presented of what the international organisations have suggested on the matter, starting from the Sendai Framework 2015-2030, in which several useful arguments are outlined. For tsunamis, a wide literature is available, thanks to the efforts of UNESCO-IOC (Intergovernmental Oceanographic Commission) and of many Tsunami Warning Systems (TWSs) operating worldwide since the half of 20th century. Then, some aspects of the recently established Tsunami Alert Centre (CAT) of INGV in Italy are described, focusing on the warning procedures and on the issue of the uncertainties in the real time estimates, which has been recently discussed within the Intergovernmental Coordination Group for the Tsunami Early Warning and Mitigation System in the north-eastern Atlantic, the Mediterranean and connected seas (ICG/NEAMTWS). Finally, an analysis of the status of the NEAMTWS after almost 15 years of implementation is proposed, underlining the key achievements obtained in the upstream component (the technological part of monitoring and alerting), but also the strong limitations of the downstream part, that in many countries, including Italy, is still the weakest part of the alerting chain, as also seen in recent events affecting the Mediterranean.