The plane impact at the Pentagon, which was at ground level, did not register a seismic signal.
Working backwards from a seismic record to determine the time of plane impacts on the towers allows you to fit the data with the events you're looking for. You would automatically attribute the spikes you see to the impacts. Why would the WTC planes hitting high up the buildings register a signal when the much closer to the ground Pentagon hit did not?
http://www.mgs.md.gov/esic/publications/download/911pentagon.pdf
Testimony from firefighter William Walsh:
http://www.nytimes.com/packages/html/nyregion/20050812_WTC_GRAPHIC/9110442.PDF
A: What else I observed in the lobby was that – there’s basically two areas of elevators. There’s elevators off to the left-hand side which are really the express elevators. That would be the elevators that’s facing north. Then on the right-hand side there’s also elevators that are express elevators, and that would be facing south. In the center of these two elevator shafts would be elevators that go to the lower floors. They were blown off the hinges. That’s where the service elevator was also.
Q: Were these elevators that went to the upper floors? They weren’t side lobby elevators?
A: No, no, I’d say that they went through floors 30 and below.
Q: And they were blown off?
A: They were blown off the hinges, and you could see the shafts. The elevators on the extreme north side and the other express elevator on the extreme south side, they looked intact to me from what I could see, the doors anyway…
William Rodriguez
"... there were only one elevator shaft (the 50A car) that went all the way to B6, the operator was inside, Mr. Griffith, and he survived with a broken ankles. He should have died burnt since on this theory the ball of fire went down."
Rich Banaciski -- Firefighter (F.D.N.Y.) [Ladder 22]
... and then I just remember there was just an explosion. It seemed like on television they blow up these buildings. It seemed like it was going all the way around like a belt, all these explosions.
Greg Brady -- E.M.T. (E.M.S.) [Battalion 6]
We were standing underneath and Captain Stone was speaking again. We heard -- I heard 3 loud explosions. I look up and the north tower is coming down now, 1 World Trade Center.
Timothy Burke -- Firefigter (F.D.N.Y.) [Engine 202]
But it seemed like I was going oh, my god, there is a secondary device because the way the building popped. I thought it was an explosion.
Ed Cachia -- Firefighter (F.D.N.Y.) [Engine 53]
...we originally had thought there was like an internal detonation explosives because it went in succession, boom, boom, boom, boom, and then the tower came down.
Frank Campagna -- Firefighter (F.D.N.Y.) [Ladder 11]
You see three explosions and then the whole thing coming down.
Craig Carlsen -- Firefighter (F.D.N.Y.) [Ladder 8]
... you just heard explosions coming from building two, the south tower. It seemed like it took forever, but there were about ten explosions.
Jason Charles -- E.M.T. (E.M.S.)
... and then I heard an explosion from up, from up above, and I froze and I was like, oh, s___, I'm dead because I thought the debris was going to hit me in the head and that was it.
Frank Cruthers -- Chief (F.D.N.Y.) [Citywide Tour Commander]
.. there was what appeared to be at first an explosion. It appeared at the very top, simultaneously from all four sides, materials shot out horizontally. And then there seemed to be a momentary delay before you could see the beginning of the collapse.
Kevin Darnowski -- Paramedic (E.M.S.)
I heard three explosions, and then we heard like groaning and grinding, and tower two started to come down.
Dominick Derubbio -- Battalion Chief (F.D.N.Y.) [Division 8]
It was weird how it started to come down. It looked like it was a timed explosion ...
Karin Deshore -- Captain (E.M.S.)
Somewhere around the middle of the World Trade Center, there was this orange and red flash coming out. Initially it was just one flash. Then this flash just kept popping all the way around the building and that building had started to explode.
Brian Dixon -- Battalion Chief (F.D.N.Y.)
... the lowest floor of fire in the south tower actually looked like someone had planted explosives around it because the whole bottom I could see -- I could see two sides of it and the other side -- it just looked like that floor blew out. I looked up and you could actually see everything blew out on the one floor. I thought, geez, this looks like an explosion up there, it blew out.
Michael Donovan -- Captain (F.D.N.Y.)
I thought there had been an explosion or a bomb that they had blown up there.
James Drury -- Assistant Commissioner (F.D.N.Y.)
I should say that people in the street and myself included thought that the roar was so loud that the explosive - bombs were going off inside the building.
.... As I said I thought the terrorists planted explosives somewhere in the building. That's how loud it was, crackling explosive, a wall.
Thomas Fitzpatrick -- Deputy Commissioner for Administration (F.D.N.Y.)
Some people thought it was an explosion. I don't think I remember that. I remember seeing it, it looked like sparkling around one specific layer of the building.... exactly the way it looks when they show you those implosions on TV.
Gary Gates -- Lieutenant (F.D.N.Y.)
So the explosion, what I realized later, had to be the start of the collapse. It was the way the building appeared to blowout from both sides. I'm looking at the face of it, and all we see is the two sides of the building just blowing out and coming apart like this, as I said, like the top of a volcano.
Kevin Gorman -- Firefighter (F.D.N.Y.) [Ladder 22]
... I thought that when I looked in the direction of the Trade Center before it came down, before No. 2 came down, that I saw low-level flashes.
Gregg Hansson -- Lieutenant (F.D.N.Y.)
Then a large explosion took place. In my estimation that was the tower coming down, but at that time I did not know what that was. I thought some type of bomb had gone off.
Timothy Julian -- Firefighter (F.D.N.Y.) [Ladder 118]
You know, and I just heard like an explosion and then cracking type of noise, and then it sounded like a freight train, rumbling and picking up speed, and I remember I looked up, and I saw it coming down.
John Malley -- Firefighter (F.D.N.Y.) [Ladder 22]
I felt the rumbling, and then I felt the force coming at me. I was like, what the hell is that? In my mind it was a bomb going off.
James McKinley -- E.M.T. (E.M.S.)
After that I heard this huge explosion, I thought it was a boiler exploding or something. Next thing you know this huge cloud of smoke is coming at us, so we're running.
Joseph Meola -- Firefighter (F.D.N.Y.) [Engine 91]
As we are looking up at the building, what I saw was, it looked like the building was blowing out on all four sides. We actually heard the pops. Didn't realize it was the falling -- you know, you heard the pops of the building. You thought it was just blowing out.
Kevin Murray -- Firefighter (F.D.N.Y.) [Ladder 18]
When the tower started -- there was a big explosion that I heard and someone screamed that it was coming down...
Janice Olszewski -- Captain (E.M.S.)
I thought it was an explosion or a secondary device, a bomb, the jet -- plane exploding, whatever.
Daniel Rivera -- Paramedic (E.M.S.) [Battalion 31]
At first I thought it was -- do you ever see professional demolition where they set the charges on certain floors and then you hear "Pop, pop, pop, pop, pop"? That's exactly what -- because I thought it was that.
Angel Rivera -- Firefighter (F.D.N.Y.)
[in the Marriott:] So we walk all the way up, no problem. Then we hear the explosion and debris falling. We were looking out of the windows and see body parts all over the place. It was scary. It was very sad.
We searched 14, 15, went in one lobby, we came out the other way, we went in one stairway, came up -- when we hit the 19th floor, something horrendous happened. It was like a bomb went off. We thought we were dead. The whole building shook. The brick coming out of -- the door to the hallway into the hotel blew off like somebody had thrown it all over the place. It shook all over the place. We were thrown on the floor. We looked inside the lobby after everything calmed down, and everything was collapsed. The building was still shaking and we're still hearing explosions going on everywhere, so we decided let's get out of here.
Kenneth Rogers -- Firefighter (F.D.N.Y.)
I figured it was a bomb, because it looked like a synchronized deliberate kind of thing. I was there in '93.
Patrick Scaringello -- Lieutenant (E.M.S.)
I started to treat patients on my own when I heard the explosion from up above. I looked up, I saw smoke and flame and then I saw the top tower tilt, start to twist and lean.
Mark Steffens -- Division Chief (E.M.S.)
Then there was another it sounded like an explosion and heavy white powder...
John Sudnik -- Battalion Chief (F.D.N.Y.)
Then we heard a loud explosion or what sounded like a loud explosion and looked up and I saw tower two start coming down. Crazy.
Jay Swithers -- Captain (E.M.S.)
I took a quick glance at the building and while I didn't see it falling, I saw a large section of it blasting out, which led me to believe it was just an explosion. I thought it was a secondary device, but I knew that we had to go.
David Timothy -- E.M.T. (E.M.S.)
The next thing I knew, you started hearing more explosions. I guess this is when the second tower started coming down.
Albert Turi -- Deputy Assistant Chief (F.D.N.Y.)
And as my eyes traveled up the building, and I was looking at the south tower, somewhere about halfway up, my initial reaction was there was a secondary explosion, and the entire floor area, a ring right around the building blew out.
Thomas Turilli -- Firefighter (F.D.N.Y.)
... it almost actually that day sounded like bombs going off, like boom, boom, boom, like seven or eight, and then just a huge wind gust just came.
. Those claims (to coin a new phrase) proved to be lulzworthy.
