The vertical stabilizer is located on the runway threshold, right before the piano keys, along with a lot of small debris. Runway will be out of action for many hours even though the bulk of the wreckage is on the grass. Aviation expert Jim Tilmon on CNN says this points to a short landing and possible control problem in the final phase of flight.
I would add that the BA 777 incident at LHR also involved a control / sink rate problem in the final phase of flight.