From what I remember, the bombs all used a similar type of timer. the Wadsworth bomb was accidentally set off by a survey team. The story was, the crew was surveying the plot of land for a new store, and one of the workers disturbed the bomb. It then made a "whirring" noise and detonated, but it did not cause any injuries to the crew or others. This leads me to believe that their timed detonator might have malfunctioned and only went off when it was disturbed. Even then, it was only a partial detonation of the pipe bomb that was intended to damage the propane tank and make it explode.
The problem with using propane tanks as a bomb is that propane tanks are rather hard to puncture. Even when Eric was shooting directly at the one of the bombs in the cafeteria, it only partially exploded. This is good, because otherwise every backyard BBQ would have the potential to become a Michael Bay movie : )
Really, the biggest mistake the boys made was filling the propane tanks all full. That would leave very little room for the gas to vaporize in the tank. The vaporized gas is what ignites and expands quickly to create the explosive force. A full tank of any combustible fuel source is usually a lot safer than an almost empty one.
I remember there was a theory on the YUKU forum that the bomb detonator may have been made from a radio controlled car, which would create the whirring noise. But, if that were the case, then it would mean that someone would have to be close by to trigger the bomb via radio control. This would also lend credence to the impression that the diversion bomb might have had a motion trigger of some kind The report states that an unidentified person was found in a nearby drainage culvert, questioned and released. The report does not give an identity for this person though. I imagine there would have been more details about this, but the shooting was probably gathering attention by then.
Subject: Wadsworth Boulevard diversion bomb. Why did it go off? 
Thu May 07, 2015 5:54 pm
