Some kinds of natural deposit can collapse, i.e. they undergo a rapid reduction in volume, when a load (such as a building) is placed on them and they become saturated with water. Such collapse can cause damage to property.
If the material below a building collapses it may cause the building foundations to rapidly subside. If the ground collapses unevenly, the resulting damage may be more severe than that caused by a uniform collapse.
A property affected by collapse of even a few millimetres may experience the following kinds of problem:
The potential for collapsible ground to be a hazard has been assessed using 1:50 000 scale digital maps of superficial deposits. These have been combined with information from scientific and engineering reports. The detailed digital data illustrated in the map are available as attributed vector polygons, as raster grids and in spreadsheet format.