Why do only some earth quakes form a tsunami?

Not all earthquakes generate tsunamis because only those occurring under specific conditions can displace a significant volume of water. Earthquakes associated with underwater tectonic plate movements, particularly those that cause vertical shifts in the ocean floor, are most likely to trigger tsunamis. Additionally, the earthquake's magnitude, depth, and location play crucial roles; shallow, powerful quakes near Coastlines are more likely to result in a tsunami than deeper or distant ones.