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《地震研究》[ISSN:1000-0666/CN:53-1062/P]

卷:

44

期数:

2021年04期

页码:

529-540

栏目:

出版日期:

2021-11-10

文章信息/Info

Title:

Study of the Wave Velocity Changes in the Focal Area of the Tonghai M_S5.0 Earthquake and the Mojiang M_S5.9 Earthquake by Ambient Noise

作者:

杨建文¹; 2; 叶 泵¹; 2; 高 琼¹; 2; 王 军¹; 2; 陈 佳¹; 2

(1.中国地震科学实验场大理中心,云南 大理671000; 2.云南大理滇西北地壳构造活动野外科学观测研究站,云南 大理671000)

Author(s):

YANG Jianwen¹; 2; YE Beng¹; 2; GAO Qiong¹; 2; WANG Jun¹; 2; CHEN Jia¹; 2

(1.Dali Center of China Earthquake Science Experimental Site,Dali 671000,Yunnan,China;2.Field Scientific Observation and Research Station on Crustal Tectonic Activities in Dali,Northwest Yunnan,Dali 671000,Yunnan,China)

关键词:

背景噪声;  波形互相关;  经验格林函数;  波速变化

Keywords:

ambient noise;  waveform cross-correlation;  the empirical Green’s function;  wave velocity change

分类号:

P315.3

DOI:

-

摘要:

利用2017年1月31日—2019年12月1日云南数字地震台网的宽频带连续波形资料,基于背景噪声互相关方法,提取了14个台站对当天经验格林函数与参考经验格林函数的直达瑞利波走时偏移来研究2018年通海5.0级、墨江5.9级地震震源区的波速变化特征。结果表明,通海5.0级和墨江5.9级地震都在一定程度上造成了震源区地壳介质速度的变化。地震发生前后,穿过地震震中和震中附近的部分台站对的瑞利波走时偏移在地震发生前的20余天表现出明显的异常特征,且短期内走时变化具有较好的同步性,但异常幅度大小和异常持续时间存在一定差异,异常台站对走时偏移变化形态为“V”或双“V”型结构,两次地震都发生在了第1个“V”型的前端。多台站对组合的平均走时偏移结果显示,两次地震造成的震源区波速的异常持续时间大概都为260 d(通海地震略长于墨江地震),但墨江地震造成的最初的走时偏移变化量和持续时间均高于通海地震。

Abstract:

Based on the ambient noise cross-correlation method,we extract the travel time shift of the direct Rayleigh-wave of the daily empirical Green’s function and the referential empirical Green’s function of 14 station pairs to study the characteristics of the wave velocity changes in the source region of the Tonghai M_S5.0 earthquake and the Mojiang M_S5.9 earthquake by using continuous seismic data recorded by the broadband stations of the Yunnan Digital Seismic Network from January 2017 to December 2019.The results show that the seismic velocity are changed in the source region by the Tonghai M_S5.0 earthquake and the Mojiang M_S5.9 earthquake in 2018 to a certain extent.Before and after the two earthquakes,the travel time shift of the Rayleigh wave of the station pairs passing through the epicenters and their vicinity shows obvious abnormal characteristics about 20 days before the earthquakes,and the travel-time changes are synchronous in the short term but there are some differences between the amplitude and the lasting-time of the anomaly of the two earthquakes.The abnormal travel-time shift of the station pairs is V-shaped or double V-shaped,and both earthquakes occurred before the appearance of the first V-shape.The average travel-time shift of multi-station pairs show that the seismic velocity changes in the source region caused by the Tonghai M_S5.0 and the Mojiang M_S5.9 earthquakes both last about 260 days.The anomaly of the Tonghai earthquake last longer than the one of the Mojiang earthquake,but in the early stage the travel-time shift is more obvious and the lasting-time of the anomaly caused by the Mojiang earthquake is longer than those caused by the Tonghai earthquake.

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备注/Memo

备注/Memo:

收稿日期:2021-05-07
基金项目:中国地震局地震监测、预报、科研三结合课题(3JH-2021045),中国地震局2021年度震情跟踪定向工作任务(2021010105)和云南省陈颙院士工作站(2014IC007)联合资助.

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更新日期/Last Update: 2021-11-10