Why does the water retract from the shoreline before a tsunami?

An earthquake pushes the water away from the land. The tsunami is when the water returns. An earthquake is caused by the movement of the earth. If the earthquake is caused by an uplift near the shore then it can push the water. If the land drops in the ocean it can pull the water down. Sooner or later the water will reach a point of equilibrium.

https://www.reddit.com/r/askscience/comments/aal64w/why_does_the_water_retract_from_the_shoreline/