Destructive tsunamis are most often generated by large earthquakes occurring at subduction interfaces, but also other “atypical” sources—defined as crustal earthquakes and non-seismic sources altogether—may cause significant tsunami threats. Tsunamis may indeed be generated by different sources, such as earthquakes, submarine or coastal landslides, volcano-related phenomena, and atmospheric perturbations. The consideration of atypical sources is important worldwide, but it is especially prominent in complex tectonic settings such as the Mediterranean, the Caribbean, or the Indonesian archipelago. The recent disasters in Indonesia in 2018, caused by the Palu-Sulawesi magnitude Mw 7.5 crustal earthquake and by the collapse of the Anak-Krakatau volcano, recall the importance of such sources. Dealing with atypical sources represents a scientific, technical, and computational challenge, which depends on the capability of quantifying and managing uncertainty efficiently and of reducing it with accurate physical modelling. Here, we first introduce the general framework in which tsunami threats are treated, and then we review the current status and the expected future development of tsunami hazard quantifications and of the tsunami warning systems in Italy, with a specific focus on the treatment of atypical sources. In Italy, where the memory of historical atypical events like the 1908 Messina earthquake or the relatively recent 2002 Stromboli tsunami is still vivid, specific attention has been indeed dedicated to the progressive development of innovative strategies to deal with such atypical sources. More specifically, we review the (national) hazard analyses and their application for coastal planning, as well as the two operating tsunami warning systems: the national warning system for seismically generated tsunamis (SiAM), whose upstream component—the CAT-INGV—is also a Tsunami Service Provider of the North-eastern Atlantic, the Mediterranean and connected seas Tsunami Warning System (NEAMTWS) coordinated by the Intergovernmental Coordination Group established by the Intergovernmental Oceanographic Commission (IOC) of UNESCO, and the local warning system for tsunamis generated by volcanic slides along the Sciara del Fuoco of Stromboli volcano. Finally, we review the state of knowledge about other potential tsunami sources that may generate significant tsunamis for the Italian coasts, but that are not presently considered in existing tsunami warning systems. This may be considered the first step towards their inclusion in the national tsunami hazard and warning programs.

破坏性海啸通常是由俯冲界面发生的大地震引起的，但其他“非典型”震源（也被定义为地壳地震和非地震震源）也可能造成严重的海啸威胁。实际上，海啸可能是由不同的来源产生的，例如地震，海底或沿海滑坡，与火山有关的现象以及大气扰动。在世界范围内，对非典型来源的考虑非常重要，但在复杂的构造环境中，例如地中海，加勒比海或印度尼西亚群岛，这一点尤为突出。帕卢-苏拉威西7.5级Mw地壳地震和阿纳克-克拉卡托火山的坍塌造成的印度尼西亚最近的灾难在2018年引起人们的回想。处理非典型来源代表科学，技术和计算上的挑战，这取决于有效地量化和管理不确定性以及通过精确的物理建模来减少不确定性的能力。在这里，我们首先介绍处理海啸威胁的总体框架，然后我们回顾意大利海啸危害量化和海啸预警系统的现状以及未来的发展，特别关注非典型来源的治疗。在意大利，对诸如1908年墨西拿地震或相对较新的2002年斯特龙博利海啸等历史性非典型事件的记忆仍然生动，实际上，人们一直特别关注逐步解决这类非典型性事件的创新战略。进一步来说，我们回顾了（国家）灾害分析及其在海岸带规划中的应用，以及两个运行中的海啸预警系统：地震海啸国家预警系统（SiAM），其上游组件CAT-INGV也是海啸。由联合国教科文组织政府间海洋学委员会（IOC）成立的政府间协调小组协调的东北大西洋，地中海及相连海啸海啸预警系统（NEAMTWS）的服务提供商，以及由火山滑坡引起的海啸当地预警系统Stromboli火山的Sciara del Fuoco。最后，我们回顾了有关其他潜在海啸源的知识状况，这些潜在海啸源可能会为意大利海岸带来重大海啸，但目前在现有的海啸预警系统中并未考虑到这些海啸。