王健^1,,
张广伟¹,
李春峰^2,3,,,
梁姗姗⁴
1. 中国地震局地壳应力研究所(地壳动力学重点实验室), 北京 100085
2. 浙江大学海洋科学系, 浙江舟山 316021
3. 青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室, 山东青岛 266237
4. 中国地震台网中心, 北京 100045

基金项目: 国家自然科学基金（41704086，41776057）和中央级公益性科研院所基本科研专项（ZDJ2016-01和ZDJ2017-04）联合资助


详细信息

作者简介: 王健, 男, 助理研究员, 主要从事海洋地球物理与地震活动研究. E-mail: wangjianhydz@163.com

通讯作者: 李春峰, 男, 教授, 博士生导师, 主要从事海洋地球物理与地球动力学研究. E-mail: cfli@zju.edu.cn

中图分类号: P315

收稿日期:2018-03-06
修回日期:2018-04-18
上线日期:2018-05-05

Correlating seismicity to Curie-point depths in the eastern margin of the Tibetan Plateau

WANG Jian^1,,
ZHANG GuangWei¹,
LI ChunFeng^2,3,,,
LIANG ShanShan⁴
1. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China
2. Department of Marine Sciences, Zhejiang University, Zhejiang Zhoushan 316021, China
3. Laboratory of Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Shandong Qingdao 266237, China
4. China Earthquake Networks Center, Beijing 100045, China


More Information

Corresponding author: LI ChunFeng,E-mail:cfli@zju.edu.cn

MSC: P315

--> Received Date: 06 March 2018
Revised Date: 18 April 2018
Available Online: 05 May 2018


摘要
摘要:本文选取不同的地壳速度分区模型，应用双差定位法对2008—2017年发生在青藏高原东缘的地震进行了重新定位，共得到4921个精确定位结果.重定位后的地震更加集中分布于龙门山断裂带、鲜水河断裂以及四川盆地南缘，震源深度多为5~20 km.根据NGDC-720地磁场模型计算了青藏高原东缘的三分量磁异常及其梯度张量，重定位后的大多数地震位于负磁异常区域以及四川盆地西南缘的强-弱磁异常边界.基于三维分形磁化模型获得了青藏高原东缘的居里点深度，并计算了磁性层的平均地温梯度，进而利用一维稳态热传导方程获得了其地壳温度结构.结果显示青藏高原东缘大多数地震均发生在居里点深度较大、地温梯度较低的区域.大多数M≥2.0地震震源区温度为100~500℃，M≥4.0地震震源区温度多为200~400℃.2008年汶川M_S8.0、2013岷县M_S6.6、2014年鲁甸M_S6.5以及2017九寨沟M_S7.0地震震源区温度均为300℃左右，而2013年芦山M_S7.0地震震源区温度接近约400℃，更多地受控于龙门山断裂带与鲜水河断裂交汇处的局部构造应力场异常.
关键词: 双差定位法/
地震活动/
NGDC-720磁异常/
居里点深度/
地壳温度结构/
青藏高原/
四川盆地

Abstract:We relocate 4921 earthquakes in the eastern margin of the Tibetan Plateau during 2008 to 2017 using two different crustal velocity models and the double-difference relocation algorithm. Our relocated earthquakes are more concentrated around the Longmenshan, Xianshuihe fault zones and southern Sichuan Basin, with most focal depths ranging 5 and 20 km. We calculate the vector and gradient tensor magnetic anomalies based on the NGDC-720 model and find that most earthquakes are located in the regions of negative anomalies, and along the southwestern margin of the Sichuan Basin as a strong-weak anomaly boundary. Curie-point depths are estimated using the centroid spectral approach based on 3D fractal magnetization model, and the average thermal gradients of the magnetic layer are calculated. Crustal temperature structures are then calculated using the 1D steady thermal conduction equation. The results show that most of the earthquakes occurred in the regions with large Curie depths and low thermal gradients. The evaluated crustal temperatures for most earthquakes hypocenters with M≥2.0 and M≥4.0 are between 100 and 500 ℃ and between 200 and 400 ℃, respectively. The 2008 M_S8.0 Wenchuan, 2013 M_S6.6 Minxian, 2014 M_S6.5 Ludian and 2017 M_S7.0 Jiuzhaigou earthquakes all occurred in the regions with estimated hypocenter temperature of about 300 ℃, whereas the hypocenter's temperature estimated for the 2013 M_S7.0 Lushan earthquake is ca. 400 ℃, more controlled by regional tectonic stress anomalies in the junction area of the Longmenshan and Xianshuihe fault zones.
Key words:Double-difference earthquake relocation/
Seismicity/
NGDC-720 magnetic anomaly/
Curie-point depth/
Crustal temperature structure/
Tibetan Plateau/
Sichuan Basin



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