I think the limit for earthquake induced tsunami’s is about 90 feet or something? (30 meters sounds familiar). But it is based on an earthquake typically has a maximum displacement. Of course the shoreline where it hits factors in as well.
But a tsunami caused by a landslide can be huge as there can be so much more mass displacing the water. There was one up in Alaska on a narrow fiord and a boat was lifted up over a point of land that was hundreds (a thousand??) feet in elevation above the normal water level. The guys lived to tell about it!
Okay - 1700-foot tall wave! The year - 1958.
http://www.sitnews.us/Kiffer/LituyaBay/070808_lituya_bay.html
Interesting article - while the max height of the wave was 1700 feet, it was far less when it hit the boats. Two boats survived. One was carried over the trees and boulders of the point of land - probably 80 feet tall.
spoiler alert to the article....
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The fisherman that made it over the point of land returned to the bay 4 or 5 years later. As soon as he entered the bay, he had a heart attack and died!