I'm running a D&D campaign and, well, the players had blown up a cave filled with explosives under a 40-metr cliff. I told them the cliff cracked and fell into the ocean. 40 meters tall, 30 meters into the land, around 60 meters along the coastline from start to finish of a crack. How would it affect the marina in a city nearby? How tall would a wave be? The cliff, I'm assuming would just slide into the water quite fast.
A tsunami with a record run-up height of 1720 feet occurred in Lituya Bay, Alaska. On the night of July 9, 1958, an earthquake along the Fairweather Fault in the Alaska Panhandle loosened about 40 million cubic yards (30.6 million cubic meters) of rock high above the northeastern shore of Lituya Bay.
Your cliff face (dimensions and size) is like icebergs calving off the glaciers around the world. Cruise ships carry passengers up to the face for pictures and occasionally they are gifted with a new iceberg breaking off the face. It makes a small wave. Your wave might be a bit bigger but not catastrophic.