2.5 Ground Motion Characteristics

Several earthquake parameters are reported in the literature for quantitatively describing the various characteristics of the ground motion. These cover characteristics such as amplitude of motion, frequency content of motion, duration of motion, etc. Loading effect of earthquake ground motion at a site is generally represented by three ground motion (GM) parameters viz. peak ground acceleration, response spectrum and acceleration time history. The combined influence of the amplitude of ground accelerations, their frequency content and the duration of the ground shaking on different structures is represented by means of response spectrum.

The three ground motion parameters i.e. peak ground acceleration (PGA) value, response spectrum and acceleration time history of a site, commonly used in the design of structure, are known as design basis ground motion parameters (DBGM).