Quick clay is normally solid, as long as it is left undisturbed. If it is overburdened and agitated, it becomes liquid. Slides of agitated quick clay can erode the ground under houses and other buildings. In contrast to e.g. rock slides and avalanches, quick clay slides have no warning signs such as cracking or fissures.
Safety considerations have been mapped
Quick clay slides can have dramatic consequences in developed areas. Safety considerations have been mapped in the most important clay areas in Norway. This information can reduce the risk of major accidents in the future.
Most extensively in Trøndelag and Eastern Norway
Zones of quick clay are found in areas containing marine clay. Marine clay occurs in areas which were previously under water, but which are now above sea level. Marine clay is found most extensively in Trøndelag and in Eastern Norway, but it is also common in some places in Western and Southern Norway.
Human impact such as construction and excavation is normally the cause of such slides, although natural causes can also trigger quick clay slides.