长白山天池火山区上地壳Q值结构

同天然地震资料相比，人工地震剖面观测资料具有震源球对称且位置已知，观测点位密集、震源和观测点呈直线排列、速度结构已知等突出优点。本文提出了一种利用人工地震振幅资料反演分层介质中Q值的新方法。在利用该方法得到Q值深度函数的基础上，综合各炮点的结果，可研究Q值沿剖面的横向变化。利用上述方法计算了长白山L1剖面上地壳的Q值值结构。发现长白山天池火山区下方Q值明显低于邻近地区，该区域位于天池地区壳内低速异常体的上部，对应于已往的火山喷发通道。

Q-VALUE STRUCTURE OF THE UPPER CRUST IN CHANGBAISHAN Mt.VOLCANIC REGION

Compared with earthquake data,artificial earthquake profiling data have a lot of advantages,such as that source is spherically symmetrical and their position is known;observational points are very dense;sources and observing points are in a straight line;and the velocity structure of the studied area can be determined exactly.In this paper,a new model to inverse the Q-values in layered medium with artificial earthquake data has been proposed.Based on the function of Q-value in depth,combining the results of each explosion points we can study the lateral variation of Q-value along the profile. Using the method above mentioned the Q-value structure of the upper crust along profile L1 in Changbaishan Mt.Region was calculated.It is found that the Q-value under the Tianci Volcano region is much smaller than that in adjacent regions.This low Q-value region locates just above the low velocity anomalous body in Tianci Region,which corresponds to the magma eruption channel in the past.