11:01 a.m.-12:10 p.m., September 11, 2001: Five Shocks Occur at Ground Zero, according to Seismological Data

The seismic record at Palisades, NY, 34 km north of the World Trade Center. [Source: Lamont-Doherty Earth Observatory] (click image to enlarge)According to a seismographical study conducted by Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York, five distinct shocks occur at the World Trade Center site. They occur at 11:01 a.m., 11:15 a.m., 11:29 a.m., 12:07 p.m., and 12:10 p.m. According to the study, the five resulting seismic signals “may have been generated by additional collapses.” [Earth Institute at Columbia University, 11/16/2001; Kim et al., 11/20/2001 ]