Towards the simultaneous generation of the three components of the seismic acceleration on rock surface

The simulation of the three components of seismic motion at a point are often needed in earthquake engineering risk studies. In addition, synthetic accelerograms should be compatible with all known features of the causative fault. In the paper, a procedure to simultaneously generate the two horizontal and the vertical components of the acceleration-time-history of a seismic event is proposed. Base functions, which may appear in the three components, are defined in terms of frequency, time of arrival and duration, regarded as random variables. These variables are related to the geometric fault parameters and to the velocities of wave propagation. The unknown amplitudes are finally determined by matching the resulting spectra to specified target functions. Although in its present stage of development the approach requires additional research, it is shown that satisfactory results have already been obtained. (orig.)