关键词: 地震层析技术, 首波, 断裂带, 海南岛

Abstract: Seismic tomography has been applied to seismology as a new technique. The application of the technique,however,is sometimes limited by the incomplete projection and parameter coupling of the models used in geosciences. In this paper,a method of reconstructing the velocity image of sedimentary basement or Moho discontinuity based on head wave data is developed.This method can also be used to correct further the depth of hypocenter. In the computation,the algebraic reconstruction technique (ART) is adopted and modified. In order to improve the computation stability and convergence of ART and SIRT algorithms,a reasonable weighting factor is suggested. The corresponding resolution and variance of different algebraic reconstruction algorithms are also analysed through numerical estimation.Using P₈ wave data from Profile Ⅰ and Ⅱ of deep seismic sounding in Hainan Island,the velocity image of the basement in the region is reconstructed. The result shows that two low velocity zones are well consistent with the important Chunjiang-Zhonghe and Ganchong-Mutang surficial fault zones,indicating that the two fault zones cut through the sedimentary basement. In addition,the segmentation features of the fault zones are well reflected on the basement velocity image.

Key words: Seismic Tomography technique, Head wave, Fault zone, Hainan Island