曹颖^1,,
黄江培^1,,,
钱佳威²,
付虹¹
1. 云南省地震局, 昆明 650224
2. 中国科学技术大学地球和空间科学学院, 合肥 230026

基金项目: 云南省地震局科技专项(2020ZX04)资助


详细信息

作者简介: 曹颖, 女, 1988年生, 工程师, 主要从事地震监测工作和地震层析成像研究.E-mail: 976242105@qq.com

通讯作者: 黄江培, 男, 1984年生, 工程师, 主要从事地震监测工作和大地测量学方面的研究.E-mail: 164909307@qq.com

中图分类号: P315

收稿日期:2020-04-02
修回日期:2021-03-12
上线日期:2021-05-10

Application of time-lapse seismic tomography based on double-difference tomography to reveal P wave velocity changes related to the 2014 Ludian M_S6.5 earthquake

CAO Ying^1,,
HUANG JiangPei^1,,,
QIAN JiaWei²,
FU Hong¹
1. Yunnan Earthquake Agency, Kunming 650224, China
2. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China


More Information

Corresponding author: HUANG JiangPei,E-mail:164909307@qq.com

MSC: P315

--> Received Date: 02 April 2020
Revised Date: 12 March 2021
Available Online: 10 May 2021


摘要
摘要:基于双差层析成像的时移层析成像方法能够获得不同时间段之间的地下介质的速度变化，且不同的数据分布和质量对结果影响较小.在本研究中我们使用云南地震区域台网所记录到的P波绝对到时及相对到时数据，利用时移层析成像方法得到了2014年鲁甸M_S6.5地震发生前后震源区高精度的P波速度变化的时空分布.结果表明：2014年鲁甸地震发生后，震源区同震期P波速度下降，但没有下降至最大，而是在震后1—4个月内下降至最大，接着P波速度开始上升，震源区开始愈合，愈合过程从浅层逐渐发展至深层，逐渐恢复至震前水平.同时发现在空间上P波速度变化与余震分布变化相一致，鲁甸地震同震应力变化与速度变化之间也有较好的一致性，所以认为地震引起的应力变化是造成鲁甸地震速度变化的一个重要原因，余震的动态和静态应力造成了震源区介质物理属性的改变从而影响了P波速度的变化.
关键词: 鲁甸地震/
时移层析成像/
P波速度变化

Abstract:Various studies have reported on temporal changes of seismic velocities in the crust before and after earthquake. New time-lapse seismic tomographic scheme based on double-difference tomography could obtain temporal velocity variations of the subsurface medium in different time periods, and it is less affected by different data distribution and quality in different time periods. In this study, we used the absolute and relative arrival data of P-wave recorded by Yunnan regional seismic network to obtain the high precision spatial-temporal distribution of P-wave velocity changes before and after the 2014 Ludian M_S6.5 earthquake by using tomoTDD method. The results show that after the Ludian Earthquake, the P-wave velocity in the source area decreased during the coseismic period, but did not drop to the minimum. It dropped to its minimum within 1-4 months after the main shock. Then P-wave velocity began to rise and the source area began to heal. The healing process developed from the shallow layer to the deep layer, and finally, restored to the level before the earthquake. At the same time, we found that the spatial change of P-wave velocity is consistent with the change of aftershock distribution. There is a good consistency between the variation of coseismic coulomb stress and P-wave velocity change. Therefore, we consider that the change of static stress caused by the earthquake is an important reason for the change of P-wave velocity. The dynamic and static stress of the aftershock results in the change of physical properties of medium in the source area, which affects the change of P-wave velocity.
Key words:Ludian earthquake/
Time-lapse seismic tomographic scheme/
P-wave velocity variation



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