How does liquefaction occur and what dangers are associated with it?
Soil beneath us stays steady unless there is no force acting to it. If there is a force, seismic waves, acts to soil near the surface, soil will start to shake and lose its rest position. All kinds of soil have different durability. Seismic waves try to destory soil's durability by shaking it. When there is an underground water in around, soil durability decreases rapidly. In a such moment that seismic waves destory the soil durability by the help of underground water, soil acts like an liquid. This situation is called liquefaction.
If there is a building above this soil, it will basicly sink. Settlements
above such enviroments would collapse easily.
There are some examples in 1999 Turkey earthquake:
Half of the first floor sink into ground
Building did not collapse but tilted