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 33.