And building collapses such as this 30-story building in Brazil (Jan 2011) 'Neighbours reported hearing a loud rumbling sound followed by what resembled an explosion.'
http://www.bbc.co.uk/news/world-latin-america-12317450
No doubt building collapses make loud sounds, but nothing we've ever seen on videos of WTC collapses is like any explosive controlled demolition. They sound just as we'd expect giant buildings to sound when they collapse.
ETA Does anybody think the Brazilian authorities should be testing for explosive residues in this case? They have no reason to. Nor did NIST have any reason to. Nor would NIST or FEMA do an arson investigation for building 7.
The building in question was under construction and fell during winds and heavy rain.
http://poleshift.ning.com/profiles/blogs/central-brazil-building

