Is it possible to lose part of the sea to an underground earthquake?

[Diceroller]

What I mean is has/can the ground open up completely draining the water from the sea, if so what then happens to this water?

[Old_Geezer]

There isn't a hole under the surface of the earth for things to fall into; if the ground opens up it tends to be through volcanic action and the lava spils out instead. Holes tend to occur inland where mines or caves collapse. One doesn't tend to get underground caves carved out under the sea.

Or are you thinking of land lifting up and islands appearing ? Of course.

[The-HouseHusband]

Put simply - NO

An earthquake happens when the earth's tectonic plates slip in relation to each other. the movement of the plates is only a few CM's but due to the high pressure against each plate an enormous amount of energy is released in the form of seismic (shock) waves.

The earth's plates float around on top of a molten layer of rock so any water entering any gap created would be immediately turned to vapour and forced back out again