三峡库区上地壳速度结构初步研究

doi:10.3969/j.issn.0253-4967.2016.02.008

摘要/Abstract

摘要：

文中利用三峡加密观测台网记录的2009年3月到2010年12月高精度地震数据，使用双差层析成像方法，联合反演了三峡库区上地壳的震源位置参数和三维上地壳P波和S波速度结构。研究结果显示，三峡库区上地壳P波速度和S波速度区域出现2个高V_P值、上低下高V_S值区，分别在巴东北部神农溪两岸-泄滩西区域和仙女山断裂带北段香溪河口附近。巴东北部神农溪两岸-泄滩西区域，较小地震的平面分布呈3条近EW向的条带，剖面陡立、向N倾，沿着P波和S波高、低速过渡带分布；香溪河口附近地震沿NNW向的仙女山断裂带分布，地质剖面显示出地震陡立线性分布，沿着高V_P值、上低下高V_S值区的过渡带展布，联合反演得到的微震面与断裂构造分布具有较好的一致性。

关键词: 双差层析成像, P波速度, S波速度, 上地壳构造, 三峡水库

Abstract:

In this paper, using the double difference tomography method, the P wave and S wave velocity structures of the earth's crust beneath the Three Gorges Reservoir are inversed based on the high-resolution seismic data of seismological stations recorded from March 2009 to December 2010. According to the research results, the P wave and S wave crust velocity zones in the Three Gorges Reservoir area show a high V_P value area and a V_S value area with value low in the lower part and high in the upper part, distributing respectively at both sides of Shennongxi River to western Xietan in the north of Badong and near the outlet of the Xiangxi River at the northern section on Xiannvshan Fault. In the region from the two sides of Shennong River in the north of Badong to the western Xietan, microseisms are distributed in three zones in near east-west direction, with steep and north-dipping sections, spreading along the high-to-low velocity transition zone of the P and S wave. On the northern section of Xiannvshan Fault, small earthquakes are distributed along the NNW-trending Xiannvshan Fault, and the geological section reveals a steep and linear distribution along the transitional zone between the high V_P value area and the V_S value that is low in the upper and high in the lower part. Joint inversion results show a good consistency of the planes of the microseisms with the distribution of active faults.

Key words: double difference tomography, P and S-wave velocity structure, upper crust structure, Three Gorges Reservoir

中图分类号:

P313.3

罗佳宏, 马文涛. 三峡库区上地壳速度结构初步研究[J]. 地震地质, 2016, 38(2): 329-341.

LUO Jia-hong, MA Wen-tao. A PRELIMINARY STUDY ON UPPER CRUSTAL VELOCITY STRUCTURE IN THE THREE GORGES RESERVOIR AREA[J]. SEISMOLOGY AND GEOLOGY, 2016, 38(2): 329-341.

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