As Rosenfeld (2004, p. 423) wrote, ‘A significant practical contribution of geomorphology is the identification of stable landforms and sites with a low probability of catastrophic or progressive involvement with natural or man-induced processes adverse to human occupance or use. Hazards exist when landscape developing processes conflict with human activity, often with catastrophic results.’ Geomorphic events can kill people and damage property. Although high-magnitude, low-frequency catastrophic events, such as hurricanes or earthquakes, gain attention because of the immediacy of large numbers of casualties and great financial losses, there are many more pervasive geomorphological changes that are also of great significance for human welfare. These may have a slower speed of onset, a longer duration, a wider spatial extent and a greater frequency of occurrence. Examples include weathering phenomena and soil erosion. In this volume we discuss both types of geomorphological hazard: the catastrophic and the pervasive.

Indeed, there is a great diversity of geomorphological hazards. One major category is mass movements, such as rockfalls, debris flows, landslides and avalanches. There are also various fluvial hazards, such as floods and river channel changes (e.g. avulsion). In volcanic areas there are disasters caused by eruptions, lava flows, ash falls and lahars. Seismic activity is another type of hazard associated with tectonic activity. In coastal environments one has inundation and erosion caused by storm surges, rapid coastal erosion and siltation, sand and dune encroachment, shoreline retreat and sea-level rise.