The tsunami which hit Fukushima was 43-49 feet tall. For seismic originated tsunamis, this is near the upper limit. Not all tsunamis are caused by earthquakes

The tsunami which hit Fukushima was 43-49 feet tall. For seismic originated tsunamis, this is near the upper limit. Not all tsunamis are caused by earthquakes though. On July 9th, 1958, there was a rockfall in Lituya Bay, Alaska. A cliff face broke off, and fell 3000 feet into the ocean. This resulting in a tsunami which stripped vegetation at up to 1720 feet in the surrounding areas. https://geology.com/records/biggest-tsunami.shtml https://geology.com/records/biggest-tsunami.shtml