How does a tsunami behave as it approaches land?
When the waves of a tsunami approach land, their appearance and behavior become dependent on several local factors. Two of the most important factors are the topography of the seafloor (bathymetry) and the actual shape of the shoreline. As a tsunami encounters shallow waters surrounding the shoreline, its height can increase from a meter (three feet) or less to over 15 meters (50 ft.). Wave heights can also be increased when concentrated on headlands or when traveling into bays having wide entrances that become progressively more narrow. The presence of an offshore coral reef can dissipate the energy of a tsunami, decreasing the impact on the shoreline. Normal wind swell may ride atop of a tsunami wave thereby increasing wave height. The image most people have of a tsunami is a large, steep wave breaking on the shore. This image is seldom the case. Most tsunamis appear as an advancing tide without having a developed wave face, resulting in rapid flooding of low-lying coastal areas. Som
