Have you ever seen a pancake collapse? Look at photos of earthquake buildings, where the floors are pancaked; it looks like a stack of pancakes.
A pancake collapse would take 90 seconds for the WTC.
William Rodriguez, a 20 year maintenance worker at the WTC and the last person to enter the building alive, felt a huge explosion under his feet (between floors in the sub=basement, B2 and B3), in the basement, before the plane crashed 95 floors above. The floors cracked and the false ceiling collapsed. A coworker ran into his office, with skin damage, yelling “explosion!”
Construction workers Phillip Morelli in North Tower sub=basement4, felt the explosion in the basement, which threw him to the floor. Some people in the basement were killed, got broken legs, from the damage done in the basement. He then ran underground to the South Tower and felt the same explosions again.
Firefighters talked of explosions all over the building, and they were likened more to the sound of bombs.
