The near surface shear wave velocity structure under a portable seismic rray inverted by genetic algorithm

• Main Authors: Shen-Chen Sheng, 沈振勝
• Other Authors: Wen, Kuo-Liang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/09666019626909440041

碩士 === 國立中央大學 === 地球物理研究所 === 90 === Follow Japan and United States seismologists' experience, We developed a method to estimate the near surface sediment's shear wave velocity structure by using microtremor data which measured from a portable seismic array. This method includes the data acquisition procedures for the field works and the analysis in the laboratory. The analysis procedures can be categorized as (1) Frequency-Wavenumber analysis to get the dispersion curve, (2) to search the good velocity models using genetic algorithm, and (3) to refine the GA searched model using traditional surface wave inversion technique. In this study, we applied our method to Guendu, Taipei and Puli basin. Puli basin is seriously damaged the 921 chi-chi earthquake. From our analysis, we found that the velocity is gradually increasing for the near surface sediments. The results show that the high speed basement appear in the depth of 400-700m for Guendu, and roughly about 10-25m deep for Puli basin.