stuffs on demolitions.........

http://www.controlled-
demolition.com/images/client/villa_panamericanas.mpg

EXCERPT:

CDI's design called for the 17 structures to fail
asymmetrically to one another, across the site, to help dampen
vibration from the fall of debris. This, coupled with CDI's carefully
timed detonation sequence, would allow the vibration "waves" created
by the fall of the individual structures to "cancel one another out"
to the extent possible. CDI's design proved successful, and no damage
was caused as a result of CDI's operations. During the 19 second
implosion sequence, the highest seismic readings recorded (less than
100' away at adjacent properties to remain) were less than ½" per
second peak particle velocity.

http://www.roadstothefuture.com/Coleman_Bridge.html

http://www.controlled-demolition.com/