thinksnow and I were having this friendly little debate last night. Through some process I don’t fully understand, we were discussing when explosives are used to bring down a building, like the Kingdome in Seattle. thinksnow’s take was that the building was imploded. My opinion was that it was exploded, since the explosives detonate outward, but the building systematically collapses inward. An implosion, I told him, is a naturally-occuring phenomenon that cannot, so far as I am aware, be 100% duplicated artificially. We discussed this for several minutes, and finally decided to let the Teeming Millions™ settle this once and for all.
thinksnow is right on this one. Here is a definition of implosion and it implying to buildings. It’s definition # 3.
Ahem. From the dictionary:
im·plo·sion n.
[ul]1.A violent collapse inward, as of a highly evacuated glass vessel.
2.Violent compression.
3.The inward collapse of a building that is being demolished in a controlled fashion by the weakening and breaking of structural members by explosives.
4.Linguistics. The pronunciation of a stop consonant with the breath drawn in.[/ul]Note definition 3, particularly. I think you were mixing up definitions 1 and 3. A building may be imploded using explosives because the explosives are not destroying the building directly, they are used to destroy key supports, which weaken the building, allowing it to collapse in a controlled way.
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I think it’s a matter of semantics. One definition of implode is “collapse inward” (Webster’s Ninth New Collegiate). The macro view is that the building implodes. The micro view is that the building collapses inward because explosives destroy structural supports.
According to my dictionary, implode means:
The “as if” in def #2 allows for other causes, so I think both your descriptions fit.
While we’re discussing proper English, it should be “Settle a debate between thinksnow and me”. 
Good thing it wasn’t a grammar thread then, huh? 
Put me down for: Building demolition uses small scale explosions to create the large scale implosion.
It would be most reasonable to refer to it as an implosion.
Hehe. Told you.
To be fair, it is somewhat a matter of semantics. Explosions start the effect, but, in general, buildings implode in upon themselves. Unless it’s a Hollywood building, in which case you’ll find pieces of it all over the damn place following a huge-mongus fiery explosion.
George Carlin’s view was that the use of imploded is incorrect, but that common usage is otherwise. (From “Brain Droppings”)
I believe the building supports are destroyed by explosives, then the building collapses… but I’m not particularly offended by the us of imploded in that context (Carlin is ;))
If anybody’s interested…