用深井观测的地震研究东川地区随rn深度变化的场地放大因子

摘要

The digital seismometers with high accuracy are installed at depths of -200 m, -100 m in deep hole and on the surface in Dongchuan. By analysis of spectra ratio, the local events (with epicentral distances between 8.5 km and 95 km, magnitudes ML =1.3～5.1) recorded are used to calculate site magnification factor at different depths (-100 m and surface) in Dongchuan. Comparing results with that at the depth of -200 m, the site magnification factors at three components of N-S, E-W and U-D corresponding to the depth of -100 m at 8 frequencies ( f = 0.75, 1.0, 1.5, 2, 3, 4, 6, and 12 Hz) are 1.0～1.49 when 0.75 ＜f＜2 Hz and 0.47～0.99 when 2 ＜f＜ 12 Hz. On the surface, site magnification factors at three components are all greater than 1, i.e. between 1.6 and 7.63. The correlation coefficients of site magnification factors for S wave and coda at the depth of -100 m and on surface are 0.82 and 0.81 when 0.75 ＜f＜ 2 Hz, 0.47 and 0.45 when 2 ＜f＜12 Hz, respectively.%采用中日合作，分别布设于东川垂直竖井中地下200 m、 100 m和地面3个位置的高精度数字化地震仪记录的地方震资料（震中距8.5～95 km，震级ML1.3～5.1），用频谱比的分析方法计算了东川地区不同深度(-100 m和地面)的场地放大因子．在8个频率（f=0.75， 1.0， 1.5， 2， 3， 4， 6和12 Hz）上所对应的在-100 m处的3个分向（N-S， E-W， U-D）的场地放大因子（与-200 m处相比），当0.75 Hz≤f≤2 Hz时，为1.0～1.49; 当2 Hz＜f＜12 Hz时，为0.47～0.99；在地面， 3个分向在8个频率上所对应的场地放大因子（与-200 m处相比）均大于1，其值为1.6～7.63． -100 m处的S波和尾波场地放大因子与地面的S波和尾波的场地放大因子的相关系数，当0.75　Hz≤f≤2　Hz频段时，分别为0.82和0.81；当2　Hz＜f＜12　Hz频段时，分别为0.47和0.45．