Social/economic impact studies: what are the impacts overall. It"s not eas to come up with [robability and severity: ex. It is wise to add a margin of safety, but the experts likely have already added margin of safety: concept of safety factor, estimate of probability of failure, ex. Earthquake resistant building - spending too much money to make one safe building. In praise of risk - value for learning about risk, if you go through life afraid of everything likely less sage. So, the perception of risk varies from person to person and the nature of the hazard regardless of expert advice affects people"s perception of it. Have knowledge of the hazard itself in general: how we understand that hazard is also important, determine the risk from that hazard in a particular area (probability of earthquake happening times severity of consequences, general risk management.