Why do tsunamis (20~ft) cause more damage and flooding than the waves that surfers surf (world record 86ft)?
In: 2
There was some amazing side-on footage of the japanese tsunami, where in front of the wave the water looked at a roughly normal level. The wave itself was probably only 1-2m high. But behind the wave, the water was totally flat…. just at the new increased height of 1-2m.
And the whole lot, that went as far as the eye could see, was all rolling towards land at speed.
Imagine that hitting land, and just having so much moving weight it just wouldn’t stop.
AN ocean wave is “[a circular motion caused by energy passing through water](https://oceanservice.noaa.gov/facts/wavesinocean.html)” which is really just a surface ripple of a relatively small amount of energy. The fact that it is a circular motion (bobbing up and down / back and forth) is why it laps gently against the dock or any large structure.
[This -“Ocean Waves: Energy, Movement, and the Coast”](https://www.thoughtco.com/what-are-waves-1435368) goes into more detail on the energy involved like wind friction at the surface etc.
A tsunami is a shock wave caused by displacement of a large amount of water, usually by a large amount of land (earthquake or undersea landslide).
The The total amount of energy is transferred quite efficiently to the water (because water is hard to compress) compared to an earthquake above the water (the air easily compresses so the shockwave in air is small).
Think of it like the game croquet. This (https://youtu.be/sQMA6Db6gvU?t=238). This transfer of energy moves the water into a powerful moving wave that travels long distances with huge energy.
Surfing waves have vertical (up and down) energy, but little forward momentum to even get inland, much less damage things inland.
Latest Answers