摘要
本文研究了300个远震事件在中国东部(100°—125°E,20°—45°N)近50个台站的P波到时残差。事件的选择标准如下:(1)地震相对于台网中心有良好的方位覆盖和距离分布,震中距遍布30°—100°;(2)绝对走时残差小于5秒;(3)体波震级大于5级。研究包括:残差的频度分布,台站绝对残差平均值和相对残差平均值,相对残差的方位角-入射角分布。结果表明:(1)中国东部地区的上地幔存在严重的横向不均匀性;(2)似乎有一条北北东走向的深层构造带将中国东部地区分成两部分,西部速度偏高,东部速度偏低,这与由重力资料反演的中国地区上地幔密度分布结果有较好的相关性。
The P-wave travel time residuals of 300 teleseismic events at 50 stations in East China(100°-125°E,20°-45°N)were studied in this paper. The criteria for selecting events are as follows: (1) Events have a good azimuth and epicentral distance distribution to the array center, with the epicentral distance range of 30°-100°; (2)the absolute residuals are less than 5. 0 Sec. ; (S)magnitude Mb is greater than 5. The study includes the frequency distributin of residuals,average absolute residuals and average relative residuals of stations,the azimuth-incidence distribution of relative residuals. The result shows that: (1)There exist considerable lateral velocity anomalies in the upper mantle under East China; (2)there seems to be a tectonic belt with NNE orientation which divides East China into two parts. Velocity is relatively high in the west part and low in the east part, which correlates well with the density distribution of the upper mantle of China from the inversion of gravity data.
出处
《中国地震》
CSCD
北大核心
1990年第4期50-56,共7页
Earthquake Research in China
