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.