<p>A hybrid method that combines the finite element method in the field of explosive dynamics and the frequency wavenumber method in the field of seismology is proposed in this study to simulate the seismic displacement generated by a 3-D explosive source in a multilayered Earth medium appropriate for any source-receiver distances based on the representation theorem. The performance of the hybrid method is demonstrated by two numerical tests. The first numerical test compares the simulated results obtained by the hybrid method with the basic theory of seismic propagation. The simulated results obtained from the hybrid method imply that the amplitudes of the P waves and Rayleigh waves produced by a 3-D cuboid explosive source lack directivity and that the particle of Rayleigh waves moves counterclockwise along an ellipse, which conforms to the basic theory of seismic propagation. The second numerical test compares the hybrid method with the traditional moment tensor-based method across synthetic scenarios. The results shows that although the amplitude and phase of the synthetic seismograms calculated by the hybrid method using the 3-D cuboid explosive model were consistent with those calculated by the traditional moment tensor-based method using an isotropic source, there were slight numerical differences indicated that the 3-D cuboid explosion source was not entirely isotropic. To verify the practicability of the proposed hybrid method, we compared between the hybrid method and the traditional moment tensor-based method via waveform simulations of underground explosions conducted by the Democratic People’s Republic of Korea (DPRK) in January 2016. For the period of 8–30 s, which is used in most seismic waveform inversions, a comparison of the observed and synthetic waveforms calculated by these two methods proves that the proposed hybrid method can better explain the real observations of the radial components (R components) and vertical components (Z components) than the moment tensor-based simulation. More importantly, this hybrid method can directly associate the far-field seismic effects with the yield of the explosion and can be coupled with a more complex explosive process. This function is not available in traditional moment tensor-based methods.</p>