Where do tsunamis mainly occur, and why?


Considering California gets many earthquakes, I’m confused why a tsunami hasn’t hit the US west coast.

In: Earth Science

That earthquakes are common in california may well be part of why the word “tsunami” comes from Japanese. Tsunami need a certain amount of space from the earthquakes in order to build up a significant amount of height, I believe.

Also, 28 tsunami (waves with a runup [height above sea level] above 1 meter) have hit the west coast of the US since 1812, according to the official US Geological Survey website, so it’s not unheard of, just not common:


It’s hard to tell whether they consider Hawai’i or Alaska to be “west coast”, which would inflate the numbers, but Cali has definitely been hit by tsunami before.

Most of the tectonic movement outside of Florida comes from lateral movement. Think of this as rubbing your hands togheter while submerged in a bowl of water.

Most tsunamis are caused when tectonic plates gets pushed under or over eachother – causing vertical movement. Think of this like clapping your hands while submerged in a bowl of water.

One of those movements cause way bigger waves than the other, although both can technically displace the same amount of water.

Another factor has to do with how the coastline looks under the water. But I don’t know too much about that part. Just wanted to throw something in here in case no one else got you covered with an answer 🙂