When a fault at the bottom of the sea suddenly moves, it typically causes a sudden displacement of the seafloor. This abrupt movement can push the overlying water column upward or downward, displacing a large volume of water. This displacement generates waves that propagate outward, potentially causing a tsunami. The process is most common and severe in subduction zones where one tectonic plate slides beneath another, locking and then suddenly slipping, releasing stored energy
. Specifically, the sudden slip on a fault can:
- Push the water above the fault upward, creating a large wave.
- Lower or raise the coastal land adjacent to the fault due to the deformation of the overlying plate, which can increase the vulnerability of the shoreline to tsunami waves
- Trigger underwater landslides, which further displace water and can amplify tsunami risk locally
- Cause seismic shaking felt as an earthquake.
Not every underwater fault movement causes a tsunami; the vertical displacement of the seafloor is a critical factor. Horizontal movements alone typically do not generate significant water displacement or tsunamis
. In summary, a sudden movement of a fault at the bottom of the sea can cause an earthquake and, if there is significant vertical displacement of the seafloor, it can generate a tsunami that may impact coastal areas nearby and even distant shores
