What is a tsunami, and why does it form?

A tsunami is a series of large ocean waves caused by the displacement of water, most commonly due to earthquakes, volcanic eruptions, underwater explosions, and sometimes landslides or meteorite impacts. These waves can travel vast distances across the open ocean, often causing widespread destruction when they reach coastal areas.

A significant factor causing tsunamis is tectonic activity. The movement of Earth's lithosphere (the outer shell of the planet) is divided into plates that float on the hot, semi-fluid asthenosphere. When these plates collide, slide past each other, or separate, they cause earthquakes. The most common and powerful tsunamis are generated from subduction zones, where one plate is forced underneath another.

When an earthquake occurs underwater, the seafloor moves abruptly, causing vertical displacement of the water column above it. This displacement generates an enormous amount of potential energy, which is released into the surrounding water, forming waves. These waves move away from the source of the earthquake in all directions. As the tsunami wave approaches the shore, its speed decreases due to the shallow water, and its height increases. This process is called shoaling. When the tsunami wave reaches the coastline, the massive amount of water can cause extensive flooding and destruction in coastal areas. In summary, a tsunami is a series of large ocean waves caused by the displacement of water due to various events, such as underwater earthquakes. The formation of a tsunami involves tectonic activity leading to the abrupt movement of the seafloor, which displaces the water column above it, generating waves that can cause widespread destruction upon reaching the shore.