Probabilistic earthquake hazard computations is done, using the EQRISK program [McGuire, 1976] or the CRISIS2012 program [Ordaz, 1991,1999]. EQRISK computes seismic hazard in terms of probabilities of exceedence vs earthquake intensity measures such as peak ground acceleration (PGA), for a given site or a grid of sites for up to eight different return periods. The site amplification is calculated with the SPEC program. This is used for making spectra of many seismic signals in a semiautomatic manner. The program is intended for two purposes: (1) making relative spectra for a series of pairs of stations terminated by the average spectra, (2) Making a series of spectra for a number of stations and events. The spectra can be corrected for distance, q, and instrument response.
This section involves a large number of programs and a more detailed description is given in section 34.