What Is a Tsunami?
A tsunami is a series of extremely long ocean waves caused by a large, sudden displacement of water. Unlike normal waves generated by wind, tsunamis are typically triggered by underwater geological events like earthquakes, volcanic eruptions, or landslides.
Section 2: How Tsunamis Are Formed
The most common cause of a tsunami is a powerful undersea earthquake. When a tectonic plate abruptly moves upward or downward, it displaces a massive column of water above it. This energy travels outward from the epicenter in all directions, creating waves with very long wavelengths in the deep ocean.
Section 3: A Practical Example
Imagine an earthquake occurs at a subduction zone, where one tectonic plate is forced under another. The overriding plate can get stuck, building up pressure. When it suddenly snaps back into place, the seafloor is thrust upward, lifting the entire column of water above it. This creates a massive bulge of water at the surface that collapses under gravity, generating the initial tsunami waves.
Section 4: Why Tsunamis Are So Destructive
In the deep ocean, a tsunami might only be a few feet high and can travel as fast as a jet plane. Its destructive power is unleashed as it approaches a coastline. The shallowing seafloor causes the wave to slow down, but its energy compresses, causing its height to increase dramatically in a process called wave shoaling. This results in a powerful surge of water that can flood far inland.