by André Rousseau
January 20, 2012
[Updated 1/21/12 to correct figures 1a, 1b, 2a, 2b and 2c, originally uploaded without study author’s notations.]
When major shocks occur at the Earth’s surface or at depth, waves of different types, magnitudes and speeds may move out from the source location. Such waves can be detected by seismometers located at recording stations, and the data from the recordings can be analyzed to learn many details of the source events. Seismic signals were recorded at stations in New York and four neighboring states on September 11, 2001 during the period when the North and South Towers (WTC1 and WTC2, respectively) were struck by airliners and collapsed, as well as during the collapse of Building 7 of the WTC, which had not been hit by a plane.
Data from the Palisades, NY recording station, located 34 km north-north-east of Manhattan, published by the Lamont-Doherty Earth Observatory of Columbia University (LDEO), provide the most detailed seismic waveforms for analysis, particularly for the determination of the locations (aerial, surface, or subsurface) and timing of the events that created the seismic waves.
Seismologists have been puzzled in their analysis of signals recorded for the events at the World Trade Center, as the contradictions are significant. They are particularly intrigued by the presence of seismic “peaks” before the collapses. This text focuses on the study of the seismic signals from Palisades. The new interpretation presented here renders the assertions of the seismic analysis of the events at the WTC, presented by the government, null and void.
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