Europhysics News Indeed, neither before nor since 9/11 have fires caused
the total collapse of a steel-framed high-rise—nor has
any other natural event, with the exception of the 1985
Mexico City earthquake, which toppled a 21-story office
building. Otherwise, the only phenomenon capable of
collapsing such buildings completely has been by way
of a procedure known as controlled demolition, whereby
explosives or other devices are used to bring down a
structure intentionally. Although NIST finally concluded
after several years of investigation that all three collapses
on 9/11 were due primarily to fires, fifteen years after
the event a growing number of architects, engineers, and
scientists are unconvinced by that explanation.
