Tsunamis

The recent 8.8-magnitude earthquake near Russia’s Kamchatka Peninsula highlights the devastating potential of tsunamis, which can ripple across vast distances and impact coastal regions worldwide.

About Tsunamis:

1. What is a Tsunami?

   • A tsunami is a series of waves caused by the displacement of water usually from a major earthquake below or near the ocean. These waves can travel across entire ocean basins, affecting regions far from the initial point of impact.

   • The term tsunami comes from the Japanese words "tsu" (harbor) and "nami" (wave), reflecting the waves’ devastating effects on coastal areas.

   Causes of Tsunamis:

   • The majority of tsunamis are triggered by earthquakes about 80% of all recorded tsunamis.

   • Other causes can include underwater volcanic activity, landslides, and, more rarely, meteorites.

   • However, not all earthquakes cause tsunamis. To generate a tsunami, the earthquake must be strong (at least 6.5 magnitude) and occur at a shallow depth (less than 70 km from the Earth’s surface), causing a vertical displacement of the seafloor.

   How Tsunamis Travel:

   • Tsunamis radiate outward in all directions, traveling across ocean basins, around islands, and into rivers and bays.

   • In deep ocean waters, tsunami waves may not be noticeable. They move quickly up to 950 km per hour (about the speed of a jet plane) and have relatively small heights (usually less than a meter).

   • As the waves approach the coast, the depth of the ocean decreases, causing the waves to increase in height, sometimes reaching 30 meters (98 feet). This is why tsunamis can be so deadly when they hit coastal regions.

   How to Recognize an Approaching Tsunami:

   • Tsunamis are difficult to predict, but there are some telltale signs. One of the most obvious indicators is the retreat of water from the shoreline, which occurs before the waves arrive. This is actually the trough of the tsunami wave, and it serves as a warning that the larger waves are approaching.

   • Coastal communities are often advised to evacuate if they notice such a retreat or receive official warnings.