why is the seismic data questionable?
It was recorded on nuclear time using very good seismic equipment which measured the impact to a hundredth of a second. The plane impacts were witnessed by the world and there can be zero dispute on what time the planes hit (you have everything from the FDR boxes to every camera in the world focused upon it).
There were massive blasts below ground some 14-17 seconds before each building was hit. Call it what you want. it's in the 911 COmmission's own report. And they "didn't have the resources to figure out just why the blasts were recorded early".
Also, you should know from military training that a plane hitting a building shouldn't measure a 2.4 magnitude earthquake on the richter scale. The WTC 1993 bomb blast was on ground level, a huge bomb, and it didn't even register. This was a subterrainin blast, it occurred before the planes hit, and it was reinforced by witness statements.
You don't have to believe it. I know it would make for a shitty day of dodging IEDs and bullets to think all day about just who had the capability to not only set off bombs in the basement, but also convince the 911 commission to avoid that topic. I think you know, homie

But you keep on waiting for CNN to tell you what to believe.