- This study presents a methodology to rank the possible earthquake events through the estimation of a reliability importance parameter, which is a function of each event's magnitude M and site-to-source distance R. This allows one to rank the importance of each design earthquake not in terms of the acceleration of a single-degree-of-freedom oscillator, but rather in terms of the displacement-based reliability of a multiple-degree-of-freedom representation of the structure. A simulation procedure is introduced that couples a technique similar to seismic hazard analysis with performance-based reliability estimates that consider interstory drift criteria. The simulation procedure allows for the inclusion of response spectra uncertainty and structural resistance uncertainties in the mass, stiffness, and damping at each story level. The reliability importance factor leads to the definition of a cumulative earthquake hazard function. This function may be used as a basis in selecting the number of design earthquakes one wishes to use depending upon the desired complexity of the analysis. Two illustrative examples are presented.