From Hurricane Irma to the Northern California wildfires, this year has seen its fair share of natural disasters. These disasters may have you thinking about what you should do in the eventuality one hits your city - how do you prepare and should you think about leaving? According to an expert, a lot of what drives large-scale evacuations is mass hysteria and fear, and most natural disasters don't require an immediate evacuation because they can be predicted, for example hurricanes.