4. Formation of seismically induced liquefaction features such as dikes is optimized by the following conditions: (1) liquefiable sediment (preferably a clean sand that has a thickness 1 m or more), (2) an overlying thin, low-permeability cap -- generally a cap of silt and clay at least 1 or 2 m in thickness (optimally about 2 to 5 m) and less than 10 m in thickness, and (3) a shallow water table (the shallower the better, and preferably less than 5 m deep). Liquefaction-induced features can form even where the top of the cap is submerged by many meters of water.