吴萍萍^1,,
丁志峰^1,,,
谭捍东²,
杨歧焱³,
王兴臣¹
1. 中国地震局地球物理研究所, 北京 100081
2. 中国地质大学(北京)地球物理与信息技术学院, 北京 100083
3. 河北地质大学地球科学学院, 石家庄 050031

基金项目: 国家重点研发计划（2017FYC1500200），国家自然科学基金项目（41704055，41830429），第67批中国博士后科学基金面上项目（2020M670395）资助


详细信息

作者简介: 吴萍萍, 女, 博士, 主要从事地震学和电磁学联合反演算法理论及应用研究.E-mail: wupingping2010@163.com

通讯作者: 丁志峰, 男, 中国地震局地球物理研究所, 研究员, 主要从事地球深部结构探测与研究.E-mail: dingzf@cea-igp.ac.cn

中图分类号: P315;P631

收稿日期:2020-08-05
修回日期:2021-05-19
上线日期:2021-08-10

Inversion MT data for the electrical structure beneath the Zhangbo seismic belt based on constraint of the V_P/V_S model

WU PingPing^1,,
DING ZhiFeng^1,,,
TAN HanDong²,
YANG QiYan³,
WANG XingChen¹
1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
2. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China
3. Hebei GEO University, Shijiazhuang 050031, China


More Information

Corresponding author: DING ZhiFeng,E-mail:dingzf@cea-igp.ac.cn

MSC: P315;P631

--> Received Date: 05 August 2020
Revised Date: 19 May 2021
Available Online: 10 August 2021


摘要
摘要:张渤地震带是中国东部地区一条重要的北西向地震活动带，获取深部精细的电性结构有助于探究该区域深部孕震环境及动力学机制等科学问题.为了提高大地电磁法深度分辨率，本文提出基于V_P/V_S波速比地震学模型约束的二维大地电磁反演法，通过理论模型合成数据检验了算法的可靠性.将算法应用于张渤地震带大地电磁测深资料，对比分析大地电磁无约束和有约束反演结果，检验算法在张渤地震带应用的有效性和实用性.最后结合已有的地质-地球物理资料，发现：反演获取的电阻率模型的电阻率梯度带与断层的空间分布吻合；唐山断裂带中上地壳表现为高阻特征，在下地壳底部有上涌的高导异常体，推测该区域深部高导区域与幔源物质侵入有关；三河—平谷断裂带浅部低阻异常与深部低阻异常不连续，地震主要分布于不连续区域；太行山山前断裂电阻率结构上表现为明显的电阻率变化梯度带，高阻异常体规模大、延伸到下地壳；张家口断裂带中下地壳高导异常区域比怀来盆地深部高导异常区域规模大，这可能暗示张家口断裂带的深部物质作用更为强烈.
关键词: 张渤地震带/
大地电磁法/
V_P/V_S波速比/
电性结构/
约束反演

Abstract:The Zhangjiakou-Bohai (Zhangbo) seismic belt is one of the major NW trending feature in eastern China. Probing the electrical structure beneath this seismic belt can help to explore the seismogenic environment and the dynamic mechanism in this region. In this paper, we present a 2-D MT inversion algorithm based on constraint of the V_P/V_S model. The validity of this constrained inversion method is verified by the synthetic model test. The inversion results by the non-constrained and constrained methods are compared and analyzed to verify the practicability of the algorithm. Finally, combined with the existing geological and geophysical data, the MT data inversion suggests that the resistivity gradient zone in the inverted model is consistent with the fault distribution. The middle and upper crust of the Tangshan fault zone shows a high resistivity anomaly. There exists an upwelling low-resistivity anomaly at the bottom of the lower crust. It is speculated that the deep low-resistivity upwelling anomaly is related to the intrusion of mantle material. The low-resistivity anomalies in the shallow and lower crust are discontinuity beneath the Sanhe-Pinggu fault zone. Earthquakes mainly occurred in the discontinuous areas, which might be caused by the upwelling of mantle material. At the piedmont fault of the Taihang Mountains, there is an apparent resistivity gradient zone, where the high resistivity anomaly body is large in scale and extends to the lower crust. The scales of low-resistivity anomalies in the middle and lower crust beneath the Zhangjiakou fault zone are larger than that of the Huailai basin, which may indicate that the upwelling mantle activity beneath Zhangjiakou is stronger than that of the Huailai basin.
Key words:Zhangbo seismic belt/
Magnetotellurics/
V_P/V_S model/
Electrical Structure/
Constrained inversion



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