More explosive evidence comes from the seismographs at Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York, 21 miles north of the WTC. This facility recorded strange seismic activity on September 11 that has still not been explained.

The above image is a seismographical readout at the time of the attacks and collapse of the WTC. You can clearly see on the top line the small peaks of the planes impacts.

But here is where it gets interesting, check out those two really BIG spikes on the 3rd and 4th lines. Those spikes represent the collapse of the towers. Notice the shape of these spikes, the highest peak is actually at the beginning. A strange anomaly when you consider the nature of a collapse is more gradual than explosive, with the vibrations becoming
more and more intense as each floor collapses onto the next.

But this isnt the case in the seismograph.

The Palisades seismic data recorded a 2.1 magnitude earthquake during the 10-second collapse of the South Tower at 9:59:04 and a 2.3 quake during the 8-second collapse of the North Tower at 10:28:31.

While the aircraft crashes caused minimal earth shaking, significant earthquakes with unusual spikes occurred at the beginning of each collapse.
Not only that, but these two unexplained spikes are more than twenty times the amplitude of the other seismic waves associated with the collapses!

This seismic record shows that as the collapses began - a huge seismic spike marked the moment the greatest energy went into the ground. The strongest jolts were all registered at the beginning of the collapses, well before the falling debris struck the earth.

THE EXPERTS SPEAK OUT

Asked about these spikes seismologist Arthur Lerner-Lam, director of Columbia University's Center for Hazards and Risk Research told the American Free Press, "This is an element of current research and discussion. It is still being investigated." According to Lerner-Lam, "The ground shaking that resulted from the collapse of the towers was extremely small."

A "sharp spike of short duration" is how seismologist Thorne
Lay of Univ. of California at Santa Cruz told AFP an underground explosion appears on a seismograph. Another seismologist, Won-Young Kim, stated that the Palisades seismographs register daily underground explosions from a quarry 20 miles away. These blasts are caused by 80,000 lbs.
of ammonium nitrate and cause local earthquakes between Magnitude 1and 2.

Evidently, the energy source that shook the ground beneath the towers was many times more powerful than the total potential energy released by the falling mass of the huge towers.