Tsunami

A tsunami is a powerful and fast-moving ocean wave caused by sudden movements in the ocean floor. Tsunamis do not crest and break like regular ocean waves.

Most tsunamis result from undersea earthquakes that abruptly shift the seafloor, displacing a massive amount of water. Less frequently, landslides or even meteorite impacts can generate tsunamis.

In deep water, tsunami waves have small wave heights relative to their long wavelengths, making them difficult to detect. However, as they approach the shore, they are pushed upward. The bottom of the wave slows due to friction with the seafloor, causing the wavelength to shorten and the wave to become unstable.

Because tsunamis have long wavelengths, there can be a significant time gap between wave crests or troughs. Either part of the wave can reach land first, making its arrival unpredictable.

Tsunamis have caused massive loss of life, including recent disasters in the Indian Ocean and Japan. To minimize risk, tsunami warning systems are now in place to help coastal communities prepare for and respond to tsunamis.