Soil response to seismic motion (cyclic dynamic loading) depends on the mechanical properties of the soil. Soil behavior under various conditions of loading is defined by one or the other of its mechanical properties. In conditions of heavy loading, soils can exhibit dynamic instability, when their deformability and the probability of destruction increase.
Dynamic properties of soils have been investigated since the 1900s and addressed in a number of renowned studies of K. Terzaghi, N.M. Gersevanov, V.A. Florin, Ya.I. Frenkel, M. Biot, and others. A qualitatively higher level of the research has been reached in the late 1960s and early 1970s after the catastrophic earthquakes of 1964 in Anchorage (Alaska) and Niigata (Japan) and the 1971 earthquake in California.