郭凌冬^1,,
付广裕^2,,,
佘雅文^1,3,
王振宇⁴,
杨君妍¹
1. 中国地震局地震预测研究所(地震预测重点实验室), 北京 100036
2. 中国地质大学(北京)地球物理与信息技术学院, 北京 100083
3. 南京大学地球科学与工程学院, 南京 210023
4. 中国地震局地球物理研究所, 北京 100081

基金项目: 国家自然科学基金（41874003）和中国地震局地震预测研究所基本科研业务费（2020IEF0502，2020IEF0508，2020IEF0708）联合资助


详细信息

作者简介: 郭凌冬, 男, 1993年生, 硕士研究生, 主要从事重力观测与解释研究.E-mail: 332458757@qq.com

通讯作者: 付广裕, 男, 教授, 博士生导师, 主要从事地震位错与重力均衡研究.E-mail: fugy@ief.ac.cn

中图分类号: P315

收稿日期:2020-11-06
修回日期:2021-04-09
上线日期:2021-09-10

Lithosphericisostasy and risk of reservoir-induced earthquakes along the Yarlung Zangbo River between Sangri and Mêdog

GUO LingDong^1,,
FU GuangYu^2,,,
SHE YaWen^1,3,
WANG ZhenYu⁴,
YANG JunYan¹
1. Key Laboratory of Earthquake Prediction, Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China
2. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China
3. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
4. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China


More Information

Corresponding author: FU GuangYu,E-mail:fugy@ief.ac.cn

MSC: P315

--> Received Date: 06 November 2020
Revised Date: 09 April 2021
Available Online: 10 September 2021


摘要
摘要:岩石圈均衡状态对于水库建设选址以及诱发地震风险研究具有重要参考价值.本文使用雅鲁藏布江桑日至墨脱段河谷的高精度重力/GNSS联测数据，得到沿河谷的自由空气以及布格重力异常.结果表明，该河谷布格重力异常在-500~-300 mGal之间变化.基于布格重力异常数据反演地壳密度结构，发现雅鲁藏布大峡谷上游自西到东莫霍面深度变化趋势为"深-浅-深"，大峡谷下游莫霍面自东北到西南逐渐变浅.在均一与分层地壳模型假设下，分别依据Airy均衡理论计算该河谷的均衡面深度，通过均衡面与莫霍面之间的差异计算均衡附加力的大小与方向.结果表明，基于均一地壳模型的计算结果存在较大的误差.通过计算得出，米林附近河谷的岩石圈均衡附加力为负值，在该地建设大型水库可能会带来较大的诱发地震风险；朗县附近岩石圈均衡附加力为正值，在该地建设水库诱发地震的风险较低.
关键词: 水库诱发地震/
布格重力异常/
均衡附加力/
地壳密度构造

Abstract:The lithospheric isostasy along the river is important for reservoir site selection and assessment of induced earthquake risk. This paper uses high-precision gravity/GNSS hybrid observation data from the valley of the Yarlung Zangbo River between Sangri and Mêdog to calculate free-air gravity and the Bouguer gravity anomalies. Results show that the Bouguer gravity anomalies vary from -500 mGal to -300 mGal. Then, the crustal density structure is inverted based on Bouguer gravity anomalies. It is found that the Moho in the upper reaches of the Yarlung Zangbo Grand Canyon exhibits a change trend of "deep-shallow-deep" from west to east as a whole, while the Moho in the downstream of the Grand Canyon gradually becomes shallower from northeast to southwest. Then, under the assumption of a homogeneous crust model and layered crust model, the depth of isostatic surface along the valley is calculated respectively according to the Airy isostatic theory. The magnitude and direction of isostatic additional force are calculated based on the difference between the isostatic surface and the Moho. The results show that the calculation based on a homogeneous crustal model yields great errors. It can be found that the lithospheric isostatic additional force of the valley near Miling is negative. The construction of large reservoirs in this area may bring a greater risk of earthquakes. However, the lithospheric isostatic additional force near Langxian is positive. Building large reservoirs in this area has a lower risk of inducing earthquakes.
Key words:Reservoir-induced earthquake/
Bouguer gravity anomaly/
Isostatic additional force/
Crustal density structure



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