福建及其邻区背景噪声面波群速度层析成像

地震 ›› 2018, Vol. 38 ›› Issue (3): 134-143.

福建及其邻区背景噪声面波群速度层析成像

张丽娜¹, 罗艳², 陈智勇³, 谢志招¹, 周蓝捷¹, 曾祥方⁴

1.福建省地震局厦门地震勘测研究中心, 福建厦门 361021;
2.中国地震局地震预测研究所, 北京 100036;
3.福建省地震局, 福建福州 350003;
4.中国科学院测量与地球物理研究所, 湖北武汉 430077

收稿日期:2017-10-31 发布日期:2019-08-15
通讯作者: 曾祥方,研究员。Email:zengxf@whigg.ac.cn
作者简介:张丽娜(1986-),女,黑龙江鸭山人,博士,工程师,主要从事地震学研究
基金资助:
福建省地震局青年基金项目(Y201710), 中国地震局地震预测研究所基本科研业务费专项(2015IES0
10302)

Surface Wave Group Velocity Tomography Imaging for Fujian Area from Ambient Noise

ZHANG Li-na¹, LUO Yan², CHEN Zhi-yong³, XIE Zhi-zhao¹, ZHOU Lan-jie¹, ZENG Xiang-fang⁴

1.Xiamen Seismic Survey Research Center, Earthquake Administration of Fujian Province, Xiamen 361021, China;
2.Institute of Earthquake Forecasting, CEA, Beijing 100036, China;
3.Earthquake Administration of Fujian Province, Fuzhou 350003, China;
4.State Key Laboratory of Geodesy and Earth’s dynamics, Institute of Geodesy and Geophysics, CAS, Wuhan 430077, China

Received:2017-10-31 Published:2019-08-15

摘要/Abstract

摘要： 基于福建及邻区108个宽频带地震台站2016年6月到7月两个月垂直和水平分量波形连续记录, 利用相位加权叠加算法提高信噪比, 计算得到108个台站对的高质量经验格林函数。对所获取的经验格林函数, 采用时频分析的方法在1~20 s频段内量取了大量高质量的Rayleigh波和Love波群速度频散数据。在此基础上, 采用基于射线追踪的二维层析成像方法反演得到了福建及其邻区1~20 s的Rayleigh波和Love波群速度分布。分辨率测试结果表明群速度分布的分辨率能达50 km。成像结果显示1~10 s的群速度分布与地壳中上部地质特征有很好的一致性, 区内的福州盆地和漳州盆地在浅层结构中表现出明显的低速异常。长周期的群速度则揭示了漳州西北的高地热区内中下地壳低速体, 政和-大埔断裂两侧的速度差异, 表明其可能是一个深大断裂, 并呈现明显的东西差异。

关键词: 背景噪声, 面波群速度, 层析成像, 福建地区

Abstract: Based on continuous waveform recording of vertical and horizontal component of broadband stations in June and July of 2016 in Fujian and its adjacent areas, we used the phase-weight stack algorithm to improve the signal to noise ratio (SNR). We obtain high quality Empirical Green Functions (EGF) of 108 stations. Applying time-frequency analysis technique from symmetrical component of EGF, we measured a large number of high quality Rayleigh and Love wave group velocity dispersion curves in the 1~20 s. To reduce error of straight ray-path assumption in 2D tomography of group velocity map, the travel-time field was computed with a finite-difference scheme and the ray-path was tracing on the travel-time field. The checkerboard test suggests the resolution of 2D tomography is up to 50 km. We obtain the Rayleigh and Love wave group velocity map of Fujian province and adjacent areas in the 1~20 s. The results show that the group velocity distribution of 1~10 s is consistent with the upper and middle geological features of the crust, and the Fuzhou and Zhangzhou basins are imaged as obvious low velocity bodies at the periods. The long period group velocity results suggest a high geothermal region at the northwest of Zhangzhou in the middle and lower crust, and the velocity difference between the two sides of Zhenghe—Dapu fault that suggest it maybe a deep and large fault and have an obvious velocity difference between east and west. The general pattern of our model crust is consistent with geological units in this region.

Key words: Tomography imaging, Ambient noise, Surface wave group velocity, Fujian area

中图分类号:

P315.7

张丽娜, 罗艳, 陈智勇, 谢志招, 周蓝捷, 曾祥方. 福建及其邻区背景噪声面波群速度层析成像[J]. 地震, 2018, 38(3): 134-143.

ZHANG Li-na, LUO Yan, CHEN Zhi-yong, XIE Zhi-zhao, ZHOU Lan-jie, ZENG Xiang-fang. Surface Wave Group Velocity Tomography Imaging for Fujian Area from Ambient Noise[J]. EARTHQUAKE, 2018, 38(3): 134-143.

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