GROUND-MOTION RELATIONS FOR EASTERN NORTH-AMERICA

Predictive relations are developed for ground motions from eastern Nor th American earthquakes of 4.0 less than or equal to M less than or eq ual to 7.25 at distances of 10 less than or equal to R less than or eq ual to 500 km. The predicted parameters are response. spectra at frequ encies of 0.5 to 20 Hz, and peak ground acceleration and velocity. The predictions are derived from an empirically based stochastic ground-m otion model. The relations differ from previous work in the improved e mpirical definition of input parameters and empirical validation of re sults. The relations are in demonstrable agreement with ground motions from earthquakes of M 4 to 5. There are insufficient data to adequate ly judge the relations at larger magnitudes, although they are consist ent with data from the Saguenay (M 5.8) and Nahanni (M 6.8) earthquake s. The underlying model parameters are constrained by empirical data f or events as large as M 6.8.