Depending on how detailed you need it to be, I would start off experimenting with a combination of blend-shapes.
Create one blend target of the normal ground.
Then create another target from the same ground distorted to look like a meteor slammed into it.
(NOTE: do NOT add or remove verticies from the ground geometry, or the blends wont work.
Then, to add detail:
*Simply instance some rubble to particles emitted from the ground geometry with attenuation set to 0, so they just spawn, then stop where they are born on the ground.
That way, during the blend animation, it looks as though the rubble is trully falling into the new rut made by the meteor.
Also apply gravity to the rubble, and make it collide with the ground AND the meteor if needed.
Then do the same style of dynamics with some building geometry pieces, vehicles, whatever
PS, some added tips are fluid mushroom-cloud smoke, more particle debris, etc.
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS