A deposit formed when loose sediment or soil is transformed into a fluid state as a result of liquefaction. The pressures generated during large earthquakes can cause the liquefied soil (usually sand) and excess water to force its way to the surface from several metres below the ground. This is often observed as 'sand boils' also called 'sand blows' or 'sand volcanoes' (as they appear to form small volcanic craters). The phenomenon may incorporate both flow of already liquefied sand from a layer below ground, and a quicksand effect whereby upward flow of water initiates liquefaction in overlying non-liquefied sandy deposits. Another observed phenomenon is land instability-cracking and movement of the ground down slope or towards unsupported margins of rivers, streams, or the coast. The failure of ground in this manner is called 'lateral spreading', and may occur on very shallow slopes of angles of only 1-2 degrees from the horizontal