Strongest tsunamis in the World Ocean and the problem of marine coastal security

We consider the problems of assessing tsunami danger for sea coasts taking into account the risk of the strongest tsunamis of seismic origin. We identify a class of particularly dangerous transoceanic events characterized by extremely high runups (up to 40-50 m) at extended coastal areas (up to 500-1000 km). In most cases these transoceanic tsunamis are caused by underwater mega-earthquakes with a magnitude of 9.0 or more occurring with a period between 200-300 and 1000-1200 years in some areas of subduction zones. The possibility of these earthquakes in subduction zones directly threatening a given coast should be taken into account in creating maps of tsunami zoning of any scale.