Tsunamis are weird, Heres how they are formed.
Most tsunamis are formed from earthquakes.When I say "Most tsunamis"I mean 80% of all tsunamis are formed from earthquakes.
There are some exceptions though, like glaciers breaking off, under water volcano eruptions, & meteors.
This is a picture of how a tsunami is made from a earthquake.
The big water bump is the tsunami forming.