[JohnBovenmyer]

I was watching a TV program ( history channel ) that a mountain avalanche in Alaska created a tidal wave over 100 feet. but, the wave was more localized in that area.

If you were watching the program I'm thinking of they found evidence of a splash line within one narrow Alaskan inlet 1400 feet high. Now that's one monster wave. On the high seas tidal waves are fast, but quite short, gaining height in shallows. They used to be thought mythic, but they have recently shown that waves over 100 feet high can occur on the high seas, likely through some other mechanism than tsunamis.

[Prophet in the wilderness]

Well,, from what I see, and saw on TV,, mountains or volcanoes that fall into the sea, can produce huge tidal waves.