|Seismographic stations||Shanksville, PA|
|Station Code||Station Name||Distance (kms)|
|SDMD||Soldier's Delight, MD||190.6|
|SSPA||Standing Stone, PA||107.6|
|MCWV||Mont Chateau, WV||92.1|
In the spring of 2002, earth scientists Won-Young Kim and G. R. Baum published Seismic Observations during September 11, 2001, Terrorist Attack in a report to the Maryland Department of Natural Resources. In that paper they established the time of the crash of Flight 93 at 10:06:05, plus or minus five seconds. Their conclusion was based on the analysis of the seismic records from the four seismic recording stations listed in the table on the right.
Kim and Baum quantified the signal-to-noise ratios (SNRs) of the relevant parts of the signals from the four stations. They found that whereas the SNRs from MCWV and SDMD signals were low, those from SSPA and MVL were about 2.5:1 and 2:1, respectively. The authors examined the three-component records from the SSPA station (vertical, North-South, and East-West), noting that "Short-period surface waves, Rg and Lg waves, are quite clear."
|This illustrations from Kim and Baum's paper shows the locations of the four seismic stations whose records they used to establish the time of Flight 93's crash.|
The authors also note that the features of the signals are consistent with an airliner crash.
The authors state with confidence their conclusion that Flight 93 crashed at 10:06.
According to the 9/11 Commission Won-Young Kim later retracted his conclusion that Flight 93 crashed at 10:06. The Commission Report states that Flight 93 crashed at 10:03, and provides the following footnote.
All of the sources that the Report cites to support its claim of a crash time of 10:03 are apparently unavailable for public inspection, including Kim's 2004 paper, for which one will search in vain on the web. The " FDR, CVR, ATC, radar, and impact site data sets" cited by the Report all remain unavailable to the public. This contrasts with Kim and Baum's 2002 paper, which documents its case for the 10:06 crash time.
2. Investigators locate 'black box' from Flight 93; widen search area in Somerset crash, post-gazette.com, 9/13/01
3. A Bell Tolls In Shanksville, CBS News, 9/11/02
4. 'America is grateful' to Flight 93 heroes, CNN.com, 9/11/02
5. , September 11 News, Heroes - Flight 93