The Ground Shake Preceding the Collapse of WTC 2

I lost track of time. You start to hear this rumble. You hear this rumble. Everything is shaking. Now I'm like, what the hell could that be. I'm thinking we're going to get bombed. This is an air raid. You hear this thunder, this rumbling. Then you see the building start to come down. Everybody's like, "Run for your lives! The building is coming down!" [Jody Bell, E.M.T. (E.M.S.)]

"We felt the ground shake. You could see the towers sway and then it just came down and I never looked back once I started running." [Lonnie Penn, E.M.T. (E.M.S.)]

"...all of a sudden the ground just started shaking. It felt like a train was running under my feet. ... The next thing we know, we look up and the tower is collapsing." [Paul Curran, Firefighter (F.D.N.Y.)]

"At around 9:50 AM, Michael and his colleague were only a block and a half a way from the WTC, when there was an ominous rumbling that grew into a roar, shaking the ground "like a thousand trains." It took them a moment to realize that the South Tower was starting to fall." [backroadsofvermont]

"I made it up onto the -- I guess you call it the concourse level, the mezzanine level, and onto the foot bridge when I started to hear -- I thought I heard an explosion of some sort, but I kind of dismissed it. I figured, ah, it's just something burning upstairs. I really didn't think of what was going on. Okay. I start going across this pedestrian bridge. I'm the only one on this bridge. I'm walking across it, and then I just remember feeling a rumble and hearing this rumbling sound that was really intense. It actually shook my bones." [Louis Cook -- Paramedic (E.M.S.)]

"Shortly before the first tower came down I remember feeling the ground shaking. I heard a terrible noise, and then debris just started flying everywhere. People started running...." [Bradley Mann, Lieutenant (E.M.S.)]

Eyewitness on the Brooklyn Bridge: "...at mid-point in the bridge, we felt a rumble like faraway thunder and turned. The impossible was happening. The south tower of the World Trade Center shook, and in what resembled an elemental act, fell to earth in a mighty shout." [Architectural Record]

Firefighters in WTC 1 stairwell as WTC 2 collapsed:

"We felt -- our whole building that we were in, when World Trade Center 2 collapsed, that was the first one to collapse. We were in World Trade Center 1. It was a tremendous explosion and tremendous shaking of our building. We thought it was our building maybe collapsed, there was a collapse above us occurring. It was tremendous shaking and like everybody dove into this stairwell and waited for, I guess, 20, 30 seconds until it settled, and that was our experience of the other building collapsing." [Brian Becker, Lieutenant (F.D.N.Y.)]

"At that point our building started to shake like an earthquake, just like shook, you wouldn't believe being in a building this size that it could shake literally this much. The lights went out, and the shaking stopped. During the shaking, which lasted it could've been 15 to 30 seconds, which is a pretty long time." [mrbellersneighborhood]

The above estimates of the shake's time period is far longer than the 10 seconds it took for WTC 2 to collapse. The video on this page shows a ground shake occurred ~13 seconds before the collapse of WTC 1. If you add the collapse time to this then the ground shake associated with the collapse of this building would have totalled ~22 seconds, therefore the above time estimates of WTC 2's ground shake may well be correct.