For most of the Tsunamis, a seismic undersea earthquake is responsible. Seismologists say only earthquakes measuring greater than 7.0 on the Richter scale can produce a major tsunami.
Some studies also say that Global Warming effects Earth’s crust due to which an earthquake takes place, giving rise to a Tsunami.
Image: https://www.voanews.com/a/what-causes-a-tsunami-117813908/167170.html
Tsunami in Indonesia is also the result of an earthquake. The magnitude of the earthquake on the Richter scale is 7.5. See here the video that the Tsunami has caused:
Video: https://www.youtube.com/watch?v=F05edMisEJE
