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地球物理学报 2003
AN APPLICATION OF WAVELET MULT-RESOLUTION ANALYSIS IN THE STUDY OF CRUST-MANTLE HETEROGENEOUS SCALE
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Abstract:
Using "zoom" multi-resolution characteristics of wavelets, we developed a method of varying scale phase analysis used to complicated waveforms of crust-mantle transitional zone (CMTZ). The method is applied to the study of heterogeneous scale of CMTZ, making the conventional phase identification from "static" into "dynamic". On the basis of Pm waveform of CMTZ along Maqin-Lanzhou-Jingbian profile, two continent-continent collision zones were reveal with the complexity coefficient method. The two zones correspond to the Maqin fault and the region of M8.5 Haiyuan earthquake, respectively. The multi-layer Pm phase under the Maqin fault and Haiyuan earthquake was obtained with the varying scale phase analysis method. The result shows that CMTZ under Haiyuan earthquake is about 20km thick, with distinguishable layers. It consists at least of 3 layers of high and low velocity alternatively, whereas CMTZ corresponding to the Maqin fault is composed of 2 thin layers. This difference in stratification and thickness shows that the contact zone between Ordos block and Qilian block differs obviously from the contact zone between Bayanhar block and Qaidam block in the present distinguishable heterogeneous scale of CMTZ, because the continent-continent collisions happened at different times and the continents interacted in different ways.