Abstract

Estimation of the coherency of ground‐motion records in two horizontal orthogonal directions at single or multiple stations is carried out using records from SMART‐1 array for several seismic events in Taiwan. Empirical coherency function is suggested for the components of records in two horizontal orthogonal directions at single‐ and multiple‐recording stations. It was also found that the coherency for the records along the major and minor principal axes at a recording station is similar to that for two randomly oriented orthogonal directions. The spatial coherency and the spatial correlation of the records are used to establish a procedure for simulating bidirectional horizontal ground motions at multiple stations, considering that the stochastic point‐source method or the stochastic finite‐fault method can be used to define the reference Fourier amplitude spectra for scenario events. Use of the proposed procedure to simulate records is illustrated for a scenario seismic event; the adequacy of the simulated records in approximating the target spatial correlation and coherency is presented.

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