How far away from a continent does an earthquake have to be to generate a huge tsunami?
Usually big tsunamis happen in subduction zones, which are located on the rim of fire around the Pacific Ocean. Unfortunately, those subduction zones are pretty close to the continents. The three biggest tsunamis: the Indonesian Tsunami, the Alaskan Tsunami, and the Chilean Tsunami occurred along the coastlines. There are usually no earthquakes in the middle of the ocean because nothing happens in the middle of the ocean. All the action happens where the subduction plate goes underneath the continent plate; all that happens at the coastlines.
