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The S wave velocity structure of the earth below Eastern Southeast Asia has been investigated by analyzing the seismogram from surface wave to multiple depth waves in the time domain and three Cartesian components simultaneously.The wave passes across the front area of subduction zone between the Philippine plate and the Asian plate.The main data are waveform comparisons,instead of the arrival times.The synthetic seismogram is calculated using the GEMINI method.The synthetic seismogram constructed by PREMAN global earth model deviates greatly from the measured one.To solve this problem,corrections are needed for the β speed structure.Corrections cover the gradient change of β_h,which turns from negative to positive in upper mantle layers as in the PREMAN,change of earth crust depth and change of zero order coefficients of β velocity function in all earth mantle layers.So,the fitting is obtained,as well as the arrival time or the waveform of Love and Rayleigh surface waves,the S wave and the repetitive depth waves ScS_2 and ScS_3.This result reveals that the Southeast Asia,being stretched due to tectonic release,has a mantle in some parts with negative anomaly of S wave velocity and vertical anisotropy in all earth mantle layers.
The S wave velocity structure of the earth below Eastern Southeast Asia has been analyzed by the seismogram from surface wave to multiple depth waves in the time domain and three Cartesian component simultaneously. The wave passes across the front area of subduction zone between the Philippine plate and the Asian plate. main data are waveform comparisons, instead of the arrival times. The synthetic seismogram is calculated using the GEMINI method. synthetic syntheticism constructed by PREMAN global earth model deviates greatly from the measured one.To solve this problem, corrections are needed for the β speed structure. Correa cover the gradient change of β_h, which turns from negative to positive in upper mantle layers as in the PREMAN, change of earth crust depth and change of zero order coefficients of β velocity function in all earth mantle layers.So, the fitting is obtained, as well as the arrival time or the waveform of Love and Rayleigh surface waves, the S wave and the repetitive depth waves ScS_2 and ScS_3.This result reveals that the Southeast Asia, being stretched due to tectonic release, has a mantle in some parts with negative anomaly of S wave velocity and vertical anisotropy in all earth mantle layers.