Soil Liquefaction - Quick Clay

Quick Clay

Quick clay, also known as Leda Clay in Canada, is a unique form of highly sensitive clay, with the tendency to change from a relatively stiff condition to a liquid mass when it is disturbed. Undisturbed quick clay resembles a water-saturated gel. When a block of clay is held in the hand and struck, however, it instantly turns into a flowing ooze, a process known as spontaneous liquefaction. Quick clay behaves this way because, although it is solid, it has a very high water content, up to 80%. The clay retains a solid structure despite the high water content, because surface tension holds water-coated flakes of clay together in a delicate structure. When the structure is broken by a shock, it reverts to a fluid state.

Quick clay is only found in the northern countries such as Russia, Canada, Alaska in the U.S., Norway, Sweden, and Finland, which were glaciated during the Pleistocene epoch.

Quick clay has been the underlying cause of many deadly landslides. In Canada alone, it has been associated with more than 250 mapped landslides. Some of these are ancient, and may have been triggered by earthquakes.