利用深源远震记录波形研究新疆准噶尔盆地边缘台站区域的地下介质分层结构

THE STUDY OF MULTILAYER-MEDIA BENEATH THE RECORDING STATIONS AT ZHUNGEER BASIN EDGE IN XINGJIANG REGION BY MEANS OF TELESEISMIC P WAVEFORMS

摘要:

为了研究新疆准噶尔盆地深部地壳和上地幔介质分层结构,本文根据Delta矩阵分解形式,按波场基本传播项进行有效组合,使得深源远震P波的综合地震图的计算变得十分简洁。
本文以该盆地边缘五个地震台的短周期地震仪记录的十个深源远震波形作为资料,通过不断调整地壳和上地幔介质模型的方式,获得了与观测波形可相比拟的综合地震图。结果表明,准噶尔盆地地下介质具有多层结构,地壳厚度深达52-60公里。同时,对深源远震P波综合地震图的研究,证实了该区地壳中上部存在低速层,Q_α值居于欧亚大陆的正常值范围内。

Abstract:

In this paper, we propose a method for the study of crust and upper mantle structure beneath the seismic recording station at Zhungeer Basin edge in Xingjiang Region. The delta matrix of separational form is recomposed by basic propagation term of wave field, resulting in a simplier computational process for the synthetic seismograms of teleseismic P wave.
Using ten teleseismic P waveforms recorded by the short-period seis mographs at stations, Aleitai, Fuyun, Kelamayi, Ganhezi and Urumqi in this basin edge, we have obtained the synthetic P waveforms in good agreement with observed P waveforms by gradually adjusting the crust and upper mantle model. Our results show that the crust of Zhungeer Basin is of multilayers; the crustal thickness is 52-60 kin, with a low velocity layer in the middle of the crust. The Q_α values for this basin are within the normal range of the Eurasian continent, It indicates the attenuation for seismic wave through this region is not very strong.