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The Extremely Low Frequency Engineering Project for Underground Exploration

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Engineering 2022年第3期8卷 13-20页

作者： Jianxun Lu Xianjun Zhuo Yong Liu guoze zhao Qingyun Di China Ship Research and Development Academy Beijing 100101China Wuhan Maritime Communication Research Institute Wuhan 430079China Institute of Geology China Earthquake AdministrationBeijing 100029China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

*** Super-low-frequency(SLF)(30-300 Hz)electromagnetic technology was first used in military to submarine deep water *** the 1950s,to strengthen the concealment and survivability of strategic missile nuclear submarines,both the United States and the Soviet Union began to study SLF communications,with the aim of achieving communications between land command centers and submarines at depths of below 100 m and distances of thousands of kilometers.

关键词： missile submarine centers

Relation between electricity structure of the crust and deformation of crustal blocks on the northeastern margin of Qinghai-Tibet Plateau

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Science China Earth Sciences 2005年第10期48卷 1613-1626页

作者： zhao guoze TANG Ji ZHAN Yan CHEN Xiaobin ZHUO Xianjun WANG Jijun XUAN Fei DENG Qianhui zhao Junmeng Institute of Geology China Earthquake AdministrationBeijing 100029China

Study on the electricity structure along a magnetotelluric(MT)sounding profile on the northeastern margin of Qinghai-Tibet Plateau indicates that four crustal blocks can be de-termined from southwest to northeast,namely Bayan Har block(BH),Qin-Qi block(QQ),Hai-yuan block(HY)or the North-South seismotectonic belt and Ordos block(OD).The BH,QQ and OD blocks display a similar electricity structure of the *** upper crust represents a high-resistivity layer and the upper part of lower crust represents a low-resistivity layer with the resis-tivity increasing gradually with depth from the lower part of lower crust to the upper *** electricity structure of the crust in these three blocks is similar to that in the complete blocks on the southern and eastern margins of the Qinghai-Tibet Plateau and belongs to normal electricity layering of the crust in slightly deformed or complete intracontinental *** crust in HY block as a boundary zone has been significantly deformed,hence its electricity layering was de-stroyed and the structure was complex and the block became a recent tectonically active and great seismo-active *** contact belts between the blocks on the northeastern margin of Qinghai-Tibet Plateau exhibit both upthrusting outward and strike-slip movement different from those on the southern and eastern margins of the *** genesis of the low-resistivity layer in the crust is analyzed and the thickness of the lithosphere is estimated in the paper.

关键词： Qinghai-Tibet Plateau crustal block electricity structure of crust tectonic deformation.

Advances in alternating electromagnetic field data processing for earthquake monitoring in China

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Science China Earth Sciences 2015年第1期58卷 172-182页

作者： zhao guoze BI YaXin WANG LiFeng HAN Bing WANG Xiao XIAO QiBin CAI JunTao ZHAN Yan CHEN XiaoBin TANG Ji WANG JiJun State Key Laboratory for Earthquake Dynamics Institute of Geology China Earthquake Administration Computer Science Research Institute Faculty of Computing and Engineering University of UlsterBelfast BT37 0QB United Kingdom Beijing Qilu Institute of Geology and Mineral Resources

The alternating electromagnetic(EM) field is one of the most sensitive physical fields related to earthquakes. There have been a number of publications reporting EM anomalies associated with earthquakes. With increasing applications and research of artificial-source extremely low frequency EM and satellite EM technologies in earthquake studies, the amount of observed data from the alternating EM method increases rapidly and exponentially, so it is imperative to develop suitable and effective methods for processing and analyzing the influx of big data. This paper presents research on the self-adaptive filter and wavelet techniques and their applications to analyzing EM data obtained from ground measurements and satellite observations, respectively. Analysis results show that the self-adaptive filter method can identify both natural- and artificial-source EM signals, and enhance the ratio between signal and noise of EM field spectra, apparent resistivity, and others. The wavelet analysis is capable of detecting possible correlation between EM anomalies and seismic events. These techniques are effective in processing and analyzing massive data obtained from EM observations.

关键词： wavelet alternating detecting capable exponentially captured apparent publications extremely processed

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Electromagnetic anomaly before earthquakes measured by electromagnetic experiments

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Earthquake Science 2009年第4期22卷 395-402页

作者： guoze zhao Yan Zhan Lifeng Wang Jijun Wang Ji Tang Qibin Xiao Xiaobin Chen Institute of Geology China Earthquake Administration Beijing 100029 China

Three experiments are carried out for earthquake monitoring using electromagnetic （EM） methods in recent years. Some earthquakes occurred in chance of the measurement time period for each experiment and the anomalies were recorded before the shocks. The observation at a site 20 km away from the epicenter of Zhangbei Ms6.2 earthquake in 1998 shows that the apparent resistivity decreases in the strike direction before and/or during the earthquake and the resistivity increases in the decline direction. This anomalous variation in apparent resistivity accounts for about 20%. The apparent resistivities at a site in the epicentral area decrease in the strike and decline directions before and/or during the earthquake and increase after shocks. The experiments using artificial electromagnetic signals with super low frequency carried out in 1999 show that the resolution and stability of electric and magnetic spectra are improved. The spectra of electric and magnetic fields and apparent resistivity at the Baodi station began to anomalously change two days before the Qian＇an earthquake with 120 km distant to the station. The anomalous variation of electric and magnetic spectra is about twice as great as normal variation and the apparent resistivity changes by about 20%. The measurements in active seismic area of Yunnan province in the year 2005 indicate that the electric and magnetic spectra anomalously change by one order before the Taoyuan earthquake about 100 km away from the observatories. But the measurements at the sites in Beijing area 2 000 km away from the epicenter do not show any anomaly.

关键词： electromagnetic anomaly apparent resistivity artificial SLF method EM experiment magnctotellurics

Evidence of crustal ‘channel flow’ in the eastern margin of Tibetan Plateau from MT measurements

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Chinese Science Bulletin 2008年第12期53卷 1887-1893页

作者： zhao guoze CHEN XiaoBin WANG LiFeng WANG JiJun TANG Ji WAN ZhanSheng ZHANG JiHong ZHAN Yan XIAO QiBin Institute of Geology China Earthquake Administration Beijing 100029 China Earthquake Administration of Shandong Province Jinan 250014 China

Magnetotelluric (MT) survey has been carried out in the eastern margin of the Tibetan Plateau and its neighboring Shimian-Leshan area, Sichuan Province. Analysis of this MT data reveals that the electric structure of the Tibetan Plateau differ much from that of the Sichuan block. In general, the electric re-sistivity of crust beneath the Sichuan block in the east is larger than that of the eastern margin of the Tibetan Plateau in the west. The crust of the plateau is divided into upper, middle, and lower layers. The middle crust is a low resistivity layer with minimum down to 3―10 Ωm about 10―15 km thick. It pre-sumably contains partial melt and/or salt-bearing fluids with low viscosity, prone to deform and flow, producing a "channel flow" under the southeastward squeeze of the eastern Tibetan Plateau. This low-resistivity layer makes the upper crust decoupled mechanically from the lower crust. In the brittle upper crust, faults are dominated by left-lateral strike-slip and thrust motions, leading to surface rising and shallow earthquakes. The low-resistivity layer also cut the Xianshuihe-Anninghe fault zone into two sections vertically. In this region, the thicknesses of upper, middle, and lower crust vary laterally, pro-ducing a transitional zone in the eastern margin of the Tibetan Plateau characterized by thicker crust and higher elevation in the west and thinner crust and lower elevation in the east.

关键词：地壳西藏高原 MT测量方法电磁场

Deep electrical structure of the Sulu orogen and neighboring areas

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Science China Earth Sciences 2009年第3期52卷 420-430页

作者： XIAO QiBin zhao guoze WANG JiJun ZHAN Yan CHEN XiaoBin TANG Ji CAI JunTao WAN ZhanSheng WANG LiFeng MA Wei ZHANG JiHong Institute of Geology China Earthquake AdministrationBeijing 100029China Earthquake Administration of Shandong Province Jinan 250014China

Because of the discovery of ultrahigh pressure metamorphic (UHPM) belt beneath the Sulu (Jiangsu Province-Shandong Province) orogen, this area has become a focused subject of current geoscience, as it has a close relationship with the evolution of the orogen and the neighboring North China craton. Probing the deep structure beneath this area would be of great significance for the geological interpretation of this issue. In this study, we make an analysis of magnetotelluric (MT) data along a profile across the Sulu orogen to provide evidence of deep structure below this region. The profile begins in west from the North China block, extending in S129°E, across the Tan-Lu fault, Sulu UHPM zone, and Sulu high pressure metamorphic (HPM) zone, and terminates in the Yangtze block in east. We use the nonlinear conjugate gradient method and TE-TM combined mode to perform inversion and interpretation of the MT data, and obtain an electrical structure image above depth of 150 km along the profile. It shows that the structure can be divided into seven sections in lateral direction, between which the electric boundaries coincide well with the major faults, such as the Tan-Lu, Haizhou-Siyang, and Jiashan-Xiangshui faults. In vertical direction the electrical structure can be subdivided into six layers of different resistivities. It is noted that there exist high-conductivity areas in crust below the North China block and Yangtze block, while such a feature is not present beneath the Sulu orogen, which is very different from the Dabie orogen. It is also observed that a fairly continuous zone of relatively low-resistivity exists at depths of 50–90 km of the electrical structure image, which is presumably a weak zone in the uppermost mantle. Just below this low-resistivity zone are the relatively high- resistivity layer of the North China block, relatively low-resistivity layer of the Sulu orogen, and relatively high-resistivity layer of the Yangtze block, all in the shallow upper m

关键词： ultrahigh pressure metamorphic belt deep electrical structure magnetotelluric sounding Sulu orogen and its neighboring areas

Automatic Anomaly Detection for Swarm Observations

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Journal of Geodesy and Geoinformation Science 2021年第1期4卷 94-108页

作者： Yaxin BI Vyron CHRISTODOULOU George WILKIE guoze zhao Peter NICHOLL Mingjun HUANG Bin HAN Ji TANG School of Computing Faculty of ComputingEngineering and the Built EnvironmentUlster UniversityNewtownabbeyBT367UK School of Architecture and the Built Environment Ulster UniversityNewtownabbeyBT367UK Institute of Geology China Earthquake AdministrationBeijing 100029China

The Swarm satellite mission was launched on 22 November 2013,it is the first European Space Agency’s constellation of three satellites,dedicated to monitoring geomagnetic field *** measurements delivered by the three satellites are very valuable for a range of applications,including the earthquake prediction ***,for more than 5 years,relatively little advancement has been achieved in establishing a systematic approach for detecting anomalies from the satellite measurements for predicting *** paper presents the challenges of developing a pragmatic framework for automatic anomaly detection and highlights innovative features of functional components *** a case study we demonstrate a functionality pipeline of the system in detecting anomalies,and present our solutions to coping with data sparsity and parameter tuning as well as insights into the differences between discovering seismic anomalies from periodic and non-periodic data observed by the Swarm satellites.

关键词： anomaly detection Swarm satellites earthquake prediction study

Earthquake Electromagnetic Precursor Anomalies Detected by a New Ground-based Observation Network

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Journal of Geodesy and Geoinformation Science 2021年第1期4卷 116-123页

作者： Bing HAN guoze zhao Lifeng WANG Ji TANG Yaxin BI Yan ZHAN Xiaobin CHEN Qibin XIAO Jihong ZHANG The State Key Laboratory of Earthquake Dynamics.Institute of Geology China Earthquake AdministrationBeijing 100029China Computer Science Research Institute Faculty of Computing and EngineeringUniversity of UlsterBelfast BT370QBU.K. Shandong Earthquake Administration Jinan 250014China

It is a debated topic if there are any observable precursor anomalies prior to the earthquake(EQ hereafter)and if the stronger EQ can be successfully *** last few decades quite a lot of observable electromagnetic(EM)precursors were published by using techniques equipped in either satellites or on ground-based *** there are only a few cases that the shortterm precursor anomalies of EM field before earthquakes were observed by using alternate EM fields on *** paper will present a new EM observation network built in recent years and show a new finding of EM field with the variation of a one-year cycle observed using the *** an example,the short-term precursor anomalies of apparent resistivity before the Yangbi EQ(Ms 5.1)occurred on March 27,2017 in Yunnan Province will be *** observed anomalous phenomena indicate that the anomaly before the EQ can be captured only if reasonable effective methods including sophisticated analytical techniques are used,and it is believed that continuously observed data on the fixed observation network for a long time is an effective means for studying anomalies that appeared before *** network can also play an important role in studying the EM environment from space.

关键词： electromagnetic observation network natural EM phenomena precursor anomaly apparent resistivity space EM environment

Study of the Structure of the Shenzhen Fault Zone with the Magnetotelluric Method

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Earthquake Research in China 2011年第2期25卷 135-147页

作者： Chen Panglong Xiao Qibin zhao guoze Ma Haoming Earthquake Administration of Guangdong Province Guangzhou 510070 China Institute of Geology China Earthquake Administration Beijing 100029 China

The magnetotelluric sounding method was used to study the active fault in Shenzhen *** magnetotelluric profiles with a dense station interval were laid out across the Shenzhen fault *** remote reference technique was used in both data observation and processing to eliminate the electromagnetic noise near the survey sites,and relatively smooth apparent resistivity curves were *** mode data and two-dimensional inversion method as NLCG were used to obtain the electrical structures *** to the surficial geology survey results on regional strata and distribution of magmatic bodies and faults,the electrical structures at depths less than 2000m of each profile were *** regional faults,the Henggang-Luohu fault and the Liantang fault,and seven local faults consistent with the electrical boundaries were verified or *** strata in the survey area were then related with the change of *** horizontal slices of depths less than 5000m indicate that the Henggang-Luohu fault and the Liantang fault bifurcate at the shallow part but tend to merge in the deep part.

关键词： Magnetotellurics Two-dimensional inversion Structure Shenzhen fault zone