As noted many times elsewhere, the breaking is just one event among 5 distinct events duting the collapse initiation sequence:
WTC2 Collapse initiation sequence:
The 5 stages of collapse initiation
1) 81, 82nd fl spandrels pull in sharply (along green and blue lines)......................inward bowing
2) 78th fl ejections.....................east wall separates into upper and lower parts
this allows tilting to begin
3) Tilting
whole upper part drops with this action
4) 75th fl east face row of ejections
5) 75th fl west wall north and south quarter of
MER panels ejected from building with flooring. NW and SW MER corners are destroyed.
The first 2 stages allow tilting to begin. Stages 4 and 5 finish the tilt and begin the fall.
The first 2 stages initiate tilt. The final 2 stages terminate tilt.
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The first visible movement is the pull in of the spandrels along the green lines and along the blue line. Then, before tilting begins, 7 ejections are seen along the low points of the staggered purple line.
The 7 78th fl ejections mark the beginning of tilting.
The hinged tilt ends with a sharp row of ejections along the 75th fl spandrel and the ejection of the corners of the west MER perimeter with beam flooring attached.
If you look at the breaking of the purple line in sequence qith the other observables, it is easier to understand.
If you look at the events in sequence, one can clearly see the distinct 78th row ejections and 75th row ejections in this gif:
Note how the emergence of the first row of ejections corresponds the the beginning of visible tilt. Note how the sharp row of ejections from the 75th fl emerges as the "hinge" breaks. After that there is a continous flow of ejections down the building.
The earliest ejections along the east face are.....
Discontinuous >>>>> discontinuous >>>> smooth ROOSD progression
This pattern is visible for anyone to see.
Therefore, both the beginning and end of tilting is marked by the emergence of distinct rows of ejections and these rows of ejections are separated by 3 floors and are noticably discontinuous. After these 2 discontinuous rows of ejections is when the smoother ejections associated with a continuous ROOSD process begins.