The digital seismometers with high accuracy are installed at depths of -200 m, -100 m in borehole and on the surface in Dongchuan. By analysis of spectra ratio, the local events (with epicentral distances between 8.5 ...The digital seismometers with high accuracy are installed at depths of -200 m, -100 m in borehole 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 Hz- [less-than or equal to] f [less-than or equal to] 2 Hz and 0.47-0.99 when 2 Hz less than or equal f less than or equal 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 Hz [less-than or equal to] f [less-than or equal to] 2 Hz, 0.47 and 0.45 when 2 Hz less than or equal f less than or equal 12 Hz, respectively.展开更多
基金Department of International Corporation of Yunnan Province and Tokyo University of Japan.
文摘The digital seismometers with high accuracy are installed at depths of -200 m, -100 m in borehole 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 Hz- [less-than or equal to] f [less-than or equal to] 2 Hz and 0.47-0.99 when 2 Hz less than or equal f less than or equal 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 Hz [less-than or equal to] f [less-than or equal to] 2 Hz, 0.47 and 0.45 when 2 Hz less than or equal f less than or equal 12 Hz, respectively.
