[UCANSEE2]

I think that the moon’s gravity is ONE of the factors, not only of Earthquakes, but of Volcanoes.

As you said, the water movement also causes movement of the ground below it. Beaches rise and fall with the tides. The ground in your yard moves, albeit very slowly.

[ETL]

As you said, the water movement also causes movement of the ground below it.

That was only a guess. I don't know for sure. I do know that water places a significant role in plate tectonics, both at the spreading centers, and even more so, at the subduction zones, where one plate is diving beneath another. Lots of seawater goes down with the subducting plate and acts as a catalyst for lowering the melting point of the rock as it reaches the hot mantle. This results in explosive volcanic activity along the margins of colliding plates.