Abstract: The Doppler effect in earthquakes can be used to determine the rupture surfaces of earthquakes,which implies that the study of Doppler effect has practical significance. However, the method to determine whether there is a Doppler effect in earthquakes is not yet mature. On the basis of studying the spatial distribution of Doppler effect, a wavelet transform method is proposed to determine whether a Doppler effect exists in earthquakes. In this study, some stations located in front of the fault slip of Wenchuan earthquake were selected for wavelet transform on the seismic records in the initial period, it was found that with the increase of epicenter distance, the high frequency amplitude of wavelet spectrum was obviously larger than the low frequency amplitude of wavelet spectrum,which indicates that although there was the effect of the media on the absorption and attenuation of seismic waves, the high frequency amplitude of the wavelet spectrum increased due to the existence of a Doppler effect. Several stations located in the vertical direction to the Wenchuan earthquake were selected for wavelet transform on the seismic records in the initial period, it was found that with the increase of epicenter distance, the high frequency amplitude of wavelet spectrum decreased rapidly. When the epicenter distance was large to a certain extent, the amplitude of wavelet spectrum in the low frequency part was obviously larger than that in the high frequency part. In this direction, the medium played a major role in the high frequency absorption and attenuation of seismic wave, and the Doppler effect did not occur.

Key words: Doppler effect, earthquake, frequency, wavelet transform, Wenchuan earthquake