The time dimension in the study of mass movements

This paper comprises two parts. The first gives the results of a study of the temporal dimensions of mass movements which was carried out by the European Centre for Geomorphological Risks in 1993. We observed that the time terminology was often inaccurate or incomplete, so we have tried to clarify concepts such as the state and mode of activity, dormancy, the return time and the age of a movement. The second part sets out a few principles which may be helpful in applying these cartographic concepts in maps of various scales and types. Its object is to give greater consideration to temporal aspects which are just as important as intensity for this type of hazard, but which are often harder to recognise and thus often ignored or overlooked, particularly in maps.