SeismicEvents

From 911Encyclopedia:

Scientific website, which analysed the seismic data of the Flight93-crash event. From this website: "...released a letter by a NASA researcher: I was able to retrieve the SSPA data. Bottom line, I don't think what this seismograph measured on 9/11/2001 in Pennsylvania is a sonic boom. First, for reference, see: http://www.galcit.caltech.edu/SonicBoom/f-18 especially the last plot. This is a known sonic boom, from a known aircraft, hitting a seismograph. 1) Notice that in all three directions, U(p), N(orth), and E(ast), the first downward peak happens simultaneously. It also shows the ground initially moving down, south, and east, which is consistent with the direction of the sonic boom from the F-18. 2) The time difference between the first downward peak and the first maximum peak is on the order of 0.15 seconds. This is consistent with the first plot of the website above showing 0.13 seconds for a pressure measurement of the sonic boom. The pressure plot is the same shape as the initial part of the seismograph displacement plot, just flipped vertically. 3) Prior to the sonic boom, the seismograph data is very flat, and there is oscillations after the boom that dampen out in a few seconds. Now referring to the SSPA data, I looked at the three axes of displacement of the earth. Plots are attached to this email. 1) In the closeup plot, sspa20sec.gif, the event does not happen simultaneously in all three axes. The Z axis on the bottom plot has the event occuring a full second after the north and east axes events, which is an eternity as far as a sonic boom is concerned. 2) The duration of the event is much greater than one would expect of a sonic boom. The shape of the event is not consistent with the "N" shape of a sonic boom. 3) In the plot sspa2min.gif, ere is a considerable amount of oscillations before the event in question. I don't know what caused these wiggles, but it doesn't look like a sonic boom to me. Sincerely, Ed Haering Seismicevent was created in mid2002 by Robb Magley, who later became member at democraticunderground-member (->). http://members.fortunecity.com/seismicevent/ http://members.fortunecity.com/seismicevent/update913.html Contact: mailto:rmagley@independence.net