Because they are being fractured with explosive, and metal and explosive together cause fragmentation.But why is it needed to assume small parts eject with incredible speed?
Indeed, but why would you need explosives to destroy a building that had suffered an aircraft strike? It certainly was not recoverable and severely increases the risk of discovery.If explosives were used they were used for the core which is deep inside the building.
In appearance, perhaps. But this style of demolition requires significant removal of entire floors of supports down to the minimum required for the building to support itself. I'm not sure how to do this covertly.At the outside it looks relatively Verinage-like except the ejections.