In my opinion: The same that goes for natural disasters (earthquakes, volcano's, tsunami's etc) goes for riots. At this moment in time we see everything on television, reporters are everywhere and if something happens, it's broadcasted all over the world.
That and the fact that a person lives on every square inch of this world makes it that alot of stuff is happening. Earthquakes that wouldn't have caused anyone any harm are now devastating, and a few people disagreeing with their leaders turn into riots. In the meantime, we get to see everything through television.
btw. good luck over there in Egypt etc.