Tsunamis are not all the same size along a coastline. The size and impact of tsunami waves can vary significantly along different parts of a coast due to a variety of factors including underwater coastal features like reefs, bays, slopes of the beach, and the shape of the sea floor. When a tsunami approaches coastal shallow waters, it undergoes transformation with wave heights typically increasing but not uniformly — some areas can experience much larger, more destructive waves due to amplification effects such as funneling in bays or inlets. Additionally, one coastal area may experience minimal effects while another nearby area sees large and violent waves. The first wave may not even be the largest in the series. These variations are influenced by local geography, wave shoaling, wave refraction, and other complex interactions of the tsunami with the coastal environment.

Therefore, the height and destructiveness of a tsunami are not consistent across a coastline but can differ widely depending on many local factors that shape and amplify the wave differently along the shore.