New Video Shows that Demolitions are Sometimes Top-Down
However, a new video shows an example of a top-down demolition of another building:
Moreover, there were numerous reports of huge explosions in the basement and other locations well below the collapse zones in the Twin Towers. For example, a stationary engineer who worked in the basement of one of the towers testified that an entire below-level garage and a 50-ton hydraulic press were demolished long before the tower collapsed.
Therefore, the demolition of the Twin Towers was, arguably, not that dissimilar from the video of many demolitions -- such as Seattle's King Dome -- where explosions and squibs are seen at the bottom of the building before the top comes down.
Because the Twin Towers were occupied, and their basements solid (buildings are usually abandoned -- and often times gutted, as in the building shown in the video above -- prior to demolition), explosions in the basement and core of the Twin Towers would not necessarily have been visible from the outside of the building. In other words, the building was still occupied, and the cores largely hidden from view, so they would not necessarily have been visible on video. In any event, some explosions were visible prior to the collapse of the Twin Towers, as the video record shows.
Prior to the final demolition sequence, the core supports were cut throughout the Twin Towers, and the basements of the Towers were apparently "hollowed out" so that the Towers could drop into the newly-created holes.
Sure, they were top-down demolitions -- like the video above. But the explosions at the base of the towers may have been much greater than those seen before the tops of buildings come down in most conventional demolitions.