a section of the crust moves under another section of crust without changing the land above from the surface the process would seem to be
It's called a tectonic shift.
These plates are always shifting, and they can either grind in opposite directions, pull away from one another, or collide to create a fault-line.
Plate tectonic movement
Earth is composed of numerous small and large plates and is commonly called the lithospheric plate. These plates are of two types, namely the continental crust and the oceanic crust. These lithospheric plates move over the viscous asthenosphere layer due to the convection current generated at the mantle. This mechanism is possible because a huge amount of heat energy is radiated towards the surface from the core of the earth.
his plate motion takes place in three different ways-
1) Convergent plate motion- here crust get destroyed.
2) Divergent plate motion- here new crust is formed.
3) Transform plate motion- here neither crust is destroyed nor created.