Why are tsunamis so different from other waves? Here's how.
While ocean waves are typically generated by wind and are relatively shallow, Tsunamis, often triggered by earthquakes, move the entire depth of the ocean.
Tsunami means “harbor wave” in Japanese, but they differ from other waves that are generated by the wind or solar system.
Tsunami waves move the entire depth of the ocean, down to the floor, which is why they create such a huge "wall" of water.
Tsunamis are generated by large disturbances, such as earthquakes, underwater landslides or volcanic eruptions. This includes the July 29 magnitude 8.8 earthquake off of Russia.
They are also faster than wind waves, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). Other waves slow as they approach land, their wave lengths decrease and their height and steepness increase. These changes usually result in them breaking, forming a typical curling wave. They then quickly recede seaward.
Tsunamis − with more energy, volume and longer wave lengths — don't break the same way, according to NOAA. Often, a tsunami's water rushes onto land, like a flood, overwhelming low-lying areas.
Tidal waves, which people used to confuse with tsunamis, are defined by gravitational interactions between the sun, moon and planet Earth, according to the U.S. Geological Survey.
When tsunamis arrive at the coastline, the first wave usually isn’t the largest, and wave periods ‒ the time between waves ‒ can last from 5 minutes to 2 hours, whereas wind waves have periods between 5 and 20 seconds.
Tsunami waves can look like a wall of water that can be upwards of 98 feet, creating dangerous conditions for hours with several waves.
Then, the water near the shoreline can recede, leaving the seafloor exposed until the next wave charges to land.