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本文根据华中、华东地区5次人工爆破时164个观测点上的首波P_n的记录资料,对P_n走时经过高程校正后采用时间项法研究该地区莫霍界面的形态。 为了节省计算机内存,提高计算速度和精度,便于在小型机上计算。本文采用了按一定规则形成的特征量数组T(i,j)和矩阵分块求逆的方法。计算得到英霍界面首波的速度v_(pn)=8.005±0.028公里/秒以及164个观测点的时间项a_i。根据本地区M—面反射波的结果。取M—面上覆介质的平均波速v_0=6.25公里/秒。反演得到各点的莫霍界面深度,并且给出该地区莫霍界面等深线轮廓图。由该图可见,区内大别山和我国南北重力梯级带以西,M—面显著变深,分别达到36公里和45公里;而盆地和大湖区,M—面变浅,一般为30公里深。莫霍界面变化的总趋势是,从东部沿海往西逐步加深,变化范围为30—45公里,平均深度为33.6公里。
Based on the recorded data of the first wave P_n at 164 observation points in five artificial explosions in Central China and East China, this paper studies the morphology of the Moho interface in the region by time-term method after elevation of P_n travel time. In order to save computer memory, improve calculation speed and accuracy, easy to calculate in the minicomputer. In this paper, we use the method of forming an array T (i, j) of features and inverting the matrix according to certain rules. The velocity v_ (pn) = 8.005 ± 0.028 km / s and the time term a_i of 164 observation points are calculated. According to the region M-surface reflection wave results. Take the M-plane covered medium average velocity v_0 = 6.25 km / sec. The Moho interface depth of each point is obtained by inversion, and the isobolographic contour of the Moho interface is given. It can be seen from the figure that the Dabie Mountain in the area and the west and M-plane to the north and south of China’s gravity cascade belonged to a depth of 36 km and 45 km, respectively. In the basin and the Great Lakes region, the M-plane became shallower, generally 30 km deep. The general trend of the Moho interface change is that it gradually deepens from the east coast to the west, with a variation range of 30-45 km and an average depth of 33.6 km.