Application Of Receiver Function Amplitude In The Study Of Crustal Structure

The study of the upper crustal mantle structure by using the travel time data of the teleseismic waveforms has become a relatively mature technique for studying the deep structure of the earth,and the researchers have little use of the waveform amplitude information.A large part of the reason from the receiver function of the peak amplitude of the resolution and stability is poor,it is difficult to measure.In recent years,with the global broadband digital seismic network construction,broadband mobile seismic array observation technology to improve and seismic instruments more and more accurate,the number and quality of telejective waveforms are greatly improved,Making it possible to recognize more subsurface fine structure information from the telecentric body wave reception function.The first part of this paper is that the shallow velocity structure is analyzed by using the first arrival wave amplitude of the receiver function.The use of the receiver function to analyze the shallow structure is a relatively simple and economical method.The influence of the shallow S wave velocity on the direct wave amplitude of the telephoto receiver function is analyzed by numerical experiments.The absolute amplitude and relative amplitude of the filter function are compared with each other,and the stability and reliability of the shallow S-wave velocity method are studied by using the receiver function amplitude information.The second part of this paper is the study of Moho surface velocity jump and density transition,which is the focus of this paper.The reception function waveform carries a primary converted wave and multiple reflected waves through the Moho plane.The magnitude of these phases is related to the velocity variation and the density change of the upper and lower layers of the Moho interface.Through the derivation of single-layer model reflection and transmission coefficient,(??-??)scanning superposition method for determin ing Moho surface velocity and density transition is proposed by using the receiver function of the primary conversion wave and multiple waves.The seismic response of different models is calculated by using the reflectivity method.The theoretical receiver function is calculated according to the method and process consistent with the actual observation waveform.According to the experimental results of different models,the influence of interface velocity and density jump on the amplitude of the received p hase is analyzed.Numerical experiments are carried out on the theoretical receiver function by using the(scan overlay method,the results show the feasibility of the method.Finally,this paper takes the northeastern margin of the Q inghai-Tibet Plateau as the study area,and the shallow S-wave velocity distribution and the velocity jump and the density transition of the Moho surface are determined by using the tele-seismic data of 36 stations in Gansu Digital Seismograph.The results show that:(1)the S-wave velocity in the Q ilian-Hexi corridor is smaller than that in the Q ilian-Hexi corridor.The S-wave velocity in the Gannan area of the terrain gradient zone is more complicated.It is found that the shallow S wave velocity is negatively correlated with the thickness of the sedimentary layer by comparing with the thickness of the latest deposited layer in the region.(2)The velocity jump of the Moho surface in the Tarim Basin is smaller than that in the eastern region,and the velocity jump in the Gansu Southeast region is complicated,and the velocity jump from southwest to northeast is gradually decreasing.For the Moho surface density jump,only to determine the minimum range of values,the overall regularity is weak.The research area of this paper is the hot area of Chinese mainland dynamics,and the result is helpful to uncover the dynamic mechanism of the Q inghai-Tibet Plateau.The research of this paper is still in the initial stage,the study of shallow velocity and Moho surface also requires the combination of other seismological methods,the main purpose of this paper is to provide some reference fo r the utilization of the receiver function.