What theory explains the causes of earthquakes and volcanoes? continental drift hydrologics plate tectonics weathering

It's plate tectonics, Earthquakes can be cause by ...

Destructive boundaries (where an oceanic plate goes under a continental plate which causes pressure to build up by friction, and when is released, causes an earthquake)

Or Conservative boundaries where 2 plates rub against each other causing pressure to build up and be released as an earthquake.

Volcanos can be made by ...

constructive plate boundaries where 2 plates pull away from each other, leaving large cracks in the earth for magma to erupt.

As well as ...

Hotspots which are on the plate itself not a boundary.

Continental drift causes volcanoes to be formed and obviously causes earthquakes