At the 121 seconds after Take-Off did buffetting occur?
As a collegue earlier stated, rupture of the vertical stab is not very likely due to large manual deflections, but what in a case of an actuator-runaway or rupture of the aft-bulkhead (referring to an earlier accident of a JAL 747, this will result in a clean rip-off of the tail..)
The first does not explain engine-involvement, but what if the engine exploded without containment, and debris of that explosion hit the tail of the aircraft just in front of the aft bulkhead, and damaging this bulkhead??
Clearly a large flock of birds -as media state- does not seem to me a cause to this....
My condolances go out to the people involved.
D