We are becoming increasingly aware of natural hazards. These have been defined by Burton and Kates (1964) as 'those elements of the physical environment harmful to man and caused by factors extraneous to him'. Any increases in our awareness of environmental hazards could arise because hazards are becoming more frequent, because hazardous events are affecting more people, or because people are becoming more conscious of the physical environment and so are more sensitive in perceiving hazards. In this article Ken Gregory and Huw Rowlands describe a project undertaken with a group of students to see if any difference could be detected between the incidence of natural hazards reported over time and the way in which such hazards are perceived to occur over time and space. Any difference between the actual occurrence of hazardous events and the way in which they are perceived is potentially important because the latter is the basis for decision making but it is the former which needs to be managed.