Sunnydale evacuation theory

As part of The Key to Byzantium I've been trying to come up with a "rational" theory to explain the evacuation of Sunnydale that doesn't involve hallucinogenic gases. How does this sound?

( Story fragment - serious scientific stuff. )

The Key to Byzantium - IV

Here's the next part of The Key to Byzantium, all comments very gratefully received. I'll be making corrections and posting to archives tomorrow evening. I hope that there are no factual or spelling errors, but if I'm wrong PLEASE let me know.

( The Key to Byzantium - IV )