"Something I've been meaning to ask," said Jack. "Who organised the evacuation of Sunnydale? The police? The national guard? Army?"
"Try none of the above. The way it happened, over the course of a few days everyone in that town seemed to get kinda frightened, started evacuating the place by themselves. Eventually there weren't enough people there to keep the power and phones running, and that spooked the rest."
"Some scientists think it was caused by infrasound," said one of the crime scene investigators working on the Winnebago.
"Ever been at a rock concert or a political rally, stood close to the speakers when they were playing a low note?"
"Sure. What about it?"
"If the note's loud but too low a frequency to hear it can still affect your body and your inner ear. Some of the really low notes, a cycle every couple of seconds, can make people feel paranoid, dizzy, nauseous. It's one of the things they have to watch out for when they're designing cars and concert halls."
"What's that got to do with Sunnydale?"
"The theory is that there was a natural resonant chamber, part of the cave system under the town. As the caves started to collapse steam or escaping gas made it vibrate in a really low note, and that set the whole place shaking. Enough people were affected to start the stampede."
"Any proof of that?"