Physical Models for Transmission of Seismic Waves
The wide variety of soil column descriptions means that it is not easy to characterize sites using simple amplification factors derived from regression of strong motion data. Accordingly, geophysicists create computer models which allow examination of likely behavior—amplification as a function of ground motion amplitude and frequency.
These more specific models are useful for predicting particular amplification at specific sites for major structures. For hazard analysis these models make it easier to approximate amplification for several standard site conditions for either high-frequency or low-frequency ground motions. These simplified factors are used in building codes.