THE INFLUENCE OF NEAR-SOURCE AND NEAR-RECEIVER STRUCTURE ON THE SPECTRUM OF P WAVES FROM NUCLEAR EXPLOSIONS

摘要

The present paper initiates a sequence of papers on the elucidation of the Earth's crust and mantle structure based on nuclear explosions, as recorded on seismic broadband stations. The teleseismic records of primary P-wave from nuclear explosions contain information about the source, the local structure surrounding the place of explosion, the influence of the mantle structure on the propagation of the wave, and finally, the crustal structure beneath the seismic station. The first arrivals and the mantle reflections generated by nuclear explosions are usually clearly identified on seismo-grams due to the impulsive nature of the source. Therefore, the analysis of traveltimes from nuclear explosions is a useful tool in detailed studies of the mantle velocity structure. The first 10-20 s of the waveform provides constrain on the local crustal velocity structure near the source and beneath the receiver. For the assumed models of the structure, an influence of near-source and near-receiver conditions on teleseismic records of the P waveform is tested. In addition to waveform modelling, spectral seismograms are introduced as a means of investigating the effects. Using the receiver function and the inversion method, the possibility of near-receiver shallow structure determination is tested.