Natural disasters are a little too easy. Face it; if we asked for people to reel off stories from the past year or so, they'd all go for earthquake in Pakistan, Hurricane Katrina, and the Boxing Day Tsunami before anything else.
Now, look at it from an interviewing perspective. What do you discuss? If they bring up Israel, or avian flu, or Zimbabwe, you can get into a decent debate. What do they think? Who's messed up? What would they change? If you're discussing the tsunami, what do you say? Yes, people died, it was bad. Right, next question...
The questions have to be designed to engender debate and to allow the sort of line of questioning that'll move the applicant out of their comfort zone a bit; let them show how much they know, and make sure it's not too easy.