I need a run-idea... Options

[Machiavelli]

....ok, basically that´s false. I already have the idea of putting my team in some serious trouble.^^ No, for real: i planned to give them a little sparetime simply because their fixers and johnsons don´t have any job for them. At some time they will walk into a bar and will see that 2 female guests are in trouble. After they hopefully help them, a massive rumble shakes the whole surrounding and everybody is streaming out on the streets. I want to create a natural desaster scenario (maybe a volcano in the near breaks out) that causes a cloud of acidic and hot cloud rushing down the streets. Additionally the spreading of contaminated earth around seattle, causes a temporarily background-count of 2 or 3 that hinders all common mages, but attracts (not aids) astral hazards. So this is going to be some kind of survival-horror thing.^^ But i don´t know if i really place it in seattle or simply somewhere the runners are at the moment, i don´t know what goal they should have (do the want to reach a not-influenced zone? already thought about looking for your loved ones - but they don´t have some^^) and i don´t know if the things i intend them to do, is really so locical that other people would think of it.

So maybe you are a little bit inspired by this basic-idea and give me some help how to go further, what you would change on the idea itself etc. Every comment is welcome. Thanks in advance.