A tsunami is a series of powerful ocean waves caused by the displacement of a large volume of water, usually as a result of an undersea earthquake, volcanic eruption, landslide, or, in rare cases, a meteorite impact. When a tsunami is generated, it propagates outward from its source, traveling across the ocean.
The journey of a tsunami can be divided into three main phases:
Generation: Tsunamis are typically generated by vertical movements of the seafloor, which displace a massive amount of water. This can occur due to tectonic plate movements during an earthquake, causing the seafloor to rise or fall suddenly. As the displaced water seeks to regain equilibrium, it forms the initial tsunami wave.
Propagation: Once formed, the tsunami wave begins to propagate or travel across the ocean. Unlike ordinary ocean waves that have short wavelengths and affect only the water's surface, tsunamis have much longer wavelengths and extend to the full depth of the ocean. As a result, they can travel vast distances across the open ocean with little loss of energy.
Inundation: As the tsunami approaches land, its behavior changes. The leading edge of the tsunami wave starts to slow down due to the interaction with shallow coastal waters, causing the wave to compress and increase in height. This results in the characteristic wall of water associated with tsunamis. When the tsunami reaches shallow water near the coastline, the wave can rapidly rise to great heights and flood the land, causing extensive damage.
It is important to note that tsunamis can travel at high speeds in the open ocean, often exceeding 500 miles per hour (800 kilometers per hour), but their height may be relatively small and inconspicuous. However, as they approach the shore and the water becomes shallower, the energy of the tsunami gets concentrated, leading to a significant increase in wave height and destructive potential.
To monitor and detect tsunamis, an international network of seismic and oceanographic sensors is in place, which helps provide timely warnings to coastal communities in the event of a tsunami threat.