温扬茂^1,2,3,,
高松¹,
许才军^1,2,3
1. 武汉大学测绘学院, 武汉 430079
2. 地球空间信息技术协同创新中心, 武汉 430079
3. 武汉大学地球空间环境与大地测量教育部重点实验室, 武汉 430079

基金项目: 国家重点研发计划项目（2018YFC1503604），国家自然科学基金（41431069，41774011，41721003），地震监测运维项目（2240504-01），地震监测预报领域项目（2018010103），川滇国家地震监测预报实验场项目（2017CESE0103）联合资助


详细信息

作者简介: 温扬茂, 男, 1982年生, 副教授, 主要从事地球物理大地测量学研究.E-mail:ymwen@sgg.whu.edu.cn

中图分类号: P315

收稿日期:2018-05-11
修回日期:2018-09-12
上线日期:2019-08-05

Seismic wave velocity change in hypocentral region of 2017 M_W7.1 Mexico earthquake from ambient noise of two stations

WEN YangMao^1,2,3,,
GAO Song¹,
XU CaiJun^1,2,3
1. School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
2. Collaborative Innovation Center of Geospatial Technology, Wuhan 430079, China
3. Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, Wuhan 430079, China


MSC: P315

--> Received Date: 11 May 2018
Revised Date: 12 September 2018
Available Online: 05 August 2019


摘要
摘要:背景噪声中包含有丰富的地球内部结构信息，可以用来监测地震波速度变化.基于墨西哥中部G.UNM和MX.TLIG两个地震台站2016年4月1日至2018年4月1日的连续波形资料，本文首先对其进行不同频带下的背景噪声互相关处理，然后采用小波变换对获取到的互相关函数进行滤波来解决台站间距过长所引起的互相关函数不稳定问题，最后分别通过Stretching方法和MWCS方法测量得到的走时偏移来提取地震波速度变化.结果表明：利用小波变换能有效提高互相关信噪比和结果精度；采用Stretching方法发现震源区浅部5~10 km的地震波速在地震中上升约0.07%，而在2~5 km的地震波速则有约0.05%的下降趋势；MWCS方法计算结果稳定性稍差，但变化趋势与Stretching结果相同.造成该地震波速变化的主要原因可能是2017年地震所引起的脆性岩层结构破裂.
关键词: 2017年墨西哥地震/
背景噪声/
Stretching方法/
MWCS方法/
地震波速变化

Abstract:Ambient noise has abundant information of the internal structure of the earth, which can be used to monitor the change of seismic wave velocity. Here, continuous waveform records from two seismic stations (G.UNM and MX.TLIG) between April 1, 2016 and April 1, 2018 were used to study the seismic wave velocity change in hypocentral region of September 19, 2017 M_W7.1 Mexico earthquake. Firstly, ambient noise at different frequency range was cross-correlated to derive Green's functions. Then the functions were filtered by wavelet transform to reduce correlation instability caused by long distance between stations. Finally, regional seismic wave velocity changes were calculated with travel time offsets determined from MWCS and Stretching method, respectively. The results indicate that the wavelet transform can improve signal to noise ratio of the cross-correlation and accuracy of results. The seismic wave velocity in the shallow crust at 5~10 km of hypocentral region raised about 0.07% but dropped about 0.05% at 2~5 km revealed by stretching method. The results from MWCS method show slightly poor stability but same trend with Stretching method. This seismic wave velocity change may be related to the damage from fault rupture caused by the earthquake.
Key words:2017 Mexico earthquake/
Ambient noise/
Stretching Method/
MWCS/
Seismic wave velocity change



PDF全文下载地址:

http://www.geophy.cn/data/article/export-pdf?id=dqwlxb_15123