First arriving wave of a tsunami. In some cases, the leading wave produces an initial depression or drop in sea level, and in other cases, an elevation or rise in sea level. When a drop in sea level occurs, sea level recession is observed.

A tsunami from a nearby source for which its destructive effects are confined to coasts within 100 km of the source (or, alternatively, less than 1 hour travel tsunami travel time). A local tsunami is usually generated by an earthquake, but can also be caused by a landslide or a pyroclastic flow from a volcanic eruption.