Forensic seismology analysis of the terrorist attacks on the pentagon

At approximately 9:38 am EDT (13:38 GMT) American Airlines flight 77 from Dulles to Los Angeles struck west side of the Pentagon. The jet, which was a Boeing 757, penetrated through several of the rings in the Pentagon and started a tremendous fire. A search for seismic records from the impact proved difficult. This is likely due to the nearly horizontal approach to the building; prelimary analysis indicated that the impact might have produced a seismic signal that was recorded at the USGS station CBN, but later work showed this not to be the case. The best work on the forensic seismology of the impact is by Dr. Kim, and can be found at this link.

Location of the pentagon and the USGS seismic station CBN.

A satellite image of the damage at the pentagon from the IKONOS satellite and Space Imaging is available here

Seismogram 1: Recording of energy orignally thought to be from the collision of Flight 77 with the Pentagon at USGS seismic station CBN. The energy is dominately surface wave energy, and gives a back azimuth roughly consistent with the pentagon, later work showed that this is an unrelated event.



This is preliminary analysis, and may change with further work.
Questions?
Email to Terry Wallace (University of Arizona) wallace@geo.arizona.edu
or Professor Keith Koper (St. Louis University) koper@eas.slu.edu
Originally posted on Sept 12, 2001
Updated August 9, 2002

Links to information on the World Trade Center collapse