Design Earthquake Based on Probabilistic Seismic Hazard Analyses

The solutions of many earthquake engineering problems involve dynamic analyses using time series. It is often desirable to base the selection of such motions on a probabilistic estimate of the seismic hazard. Probabilistic seismic hazard analyses (PSHA) is a technique for estimating the annual rate of exceedance of a specified ground motion at a site due to known and suspected earthquake sources. The disadvantage of PSHA is that the concept of a “design earthquake” is lost; i.e. there is no single event that for design or retrofit. The relative contributions of the various sources to the total seismic hazard are determined as a function of their occurrence rates and their ground-motion potential. This study describes a method wherein a design earthquake can be obtained that accurately represents the uniform Fourier hazard spectrum from a PSHA. Seismic hazard can be deaggregated to show the contribution by magnitude, distance and ground motion uncertainty.