It's an idea which can't be dismissed out of hand, but in general we know what causes major earthquakes in the particular places they occur. Localised water pile-ups are generally sea surface-only phenomena (unlike tsunamis) caused by wind or changes in air pressure. The energy generated in those events in the sea is minuscule compared to that of the long-term build-up and release of stresses that lead to major earthquakes. It's also worth remembering that most major earthquakes happen several, or many, kilometres below the actual epicentres, well away from the influence of what might be going on on top.

Phreatic volcanic eruptions are a different matter...