摘要
天然电磁波不仅沿着深度方向衰减,而且沿着水平横向方向也有同样的效应,这是大地电磁测深产生体积效应的原因之一,其分辨率随着深度的增加急剧下降.对于较低的频率范围,地表布设过于密集的测点并不能提高深部探测分辨率.在进行野外数据观测时,随着频率的降低,采集所需时间成本成指数增长,野外施工成本也随之大大增加.因此,利用疏密不同的测点分布分别约束深浅结构更为经济.本文提出一种大地电磁多尺度、多时段探测方法.在该方法中,按照探测深度将测点分为疏密不同的几组,对于小间距组别的测点,采用短的观测时间获得较高频率范围数据;对于大间距组别的测点,采用长的观测时间获得较低频率范围数据.通过合成数据和实测数据的检验,这种方式可以在节省一倍至两倍总体观测时间的条件下取得与传统观测方式等同的探测结果.论文详细阐述了多尺度、多时段探测方法的原理和实现步骤,同时利用二维、三维理论模型响应和实测数据反演验证该方法的有效性.
The magnetotelluric method(MT)realizes according to the principle that electromagnetic waves of different frequencies have different skin depths in the earth medium.The attenuation of electromagnetic waves has the same effect not only along the depth direction,but also in the horizontal lateral direction,which causes the volume effect in MT method.The resolution decreases sharply with the increase of depth.For low frequency range,the too dense observation sites have no benefits on improving the resolution and strengthening detection constraints.During field observation,with the increase of data period,both the cost of acquisition time and field construction increase exponentially and greatly.Therefore,it is more economical to use the distribution of different density observation sites to constrain the depth structure separately.In this paper,a magnetotelluric multi-scale and multi-period exploration method is proposed.Among the method,observation sites are divided into groups with different density according to the detection depth.To the sites in the small spacing group,a short observation time is designed getting the data in high frequency range,while for the sites in the large spacing groups,a long observation time is used for the low frequency data.Through the test of synthetic and real data,a equivalent detection result can be obtained under the new method with much lesser observation time totally compared to traditional observation method.This paper expounds the principle and implementation steps of the multi-scale and multi-period exploration method in detail.Meanwhile,the validity of the method is verified by the inversion of 2D and 3D synthetic data and real data.
作者
刘钟尹
陈小斌
蔡军涛
张赟昀
王培杰
LIU ZhongYin;CHEN XiaoBin;CAI JunTao;ZHANG YunYun;WANG PeiJie(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;National Institute of Natural Hazards,Ministry of Emergency Management of People's Republic of China,Beijing 100085,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第9期3761-3773,共13页
Chinese Journal of Geophysics
基金
中央级公益性科研院所基本科研业务专项(ZDJ2020-13)
中国地震局地质研究所所长基金重点项目(JB-18-02)
国家自然科学基金重大专项(41941016-01)资助。
关键词
大地电磁
野外观测
多尺度
多时段
Magnetotelluric
Field observation
Multi-scale
Multi-period
