Terminology
During the rupture, one side of the fault is pushed upwards relative to the other, and it is this type of movement that is known as thrust. They are one type of dip-slip faults. A thrust fault is a reverse fault with a dip of 45° or less. Oblique-slip faults have significant components of different slip styles. The term megathrust does not have a widely accepted rigorous definition, but is used to refer to an extremely large thrust fault, typically formed at the plate interface along a subduction zone such as the Sunda megathrust.
Read more about this topic: Megathrust Earthquake