For marketing to work well, to really grab you and force you to take action, it has to be disruptive. Most marketers have seen the frightening stat about the number of ads a typical person sees over the course of a day (was it 3,000 I think?). So the cliche of "breaking through the clutter" really does ring true.
This execution of a faux-earthquake crack recently appeared in a popular San Francisco tourist spot. It was done for the American Red Cross of the Bay Area to grab people's attention and make them aware of how bad a disaster could be. And that they needed to donate blood.
Very disruptive, very effective. And the great thing about outdoor advertising is that you can't skip it with your Tivo or block it with a Spam filter or pop-up blocker.
(See a bigger photo of people encountering this crack here.)