Japan’s location on the “Ring of Fire” makes it one of the most tsunami-prone nations in the world. Because the waves have such long wavelengths, they are almost invisible in the deep sea; fishermen would be out in the ocean and not notice anything unusual, only to return home and find their coastal villages destroyed. This led to the specific name “harbor wave.” The term was adopted into English and international scientific communities in the 20th century to distinguish these seismically triggered waves from “tidal waves,” which are caused by the gravitational pull of the moon and sun.