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Research on geo-electrical resistivity observation system specially used for earthquake monitoring in China 被引量:7
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作者 Jialiu Zhao Lanwei Wang Jiadong Qian 《Earthquake Science》 CSCD 2011年第6期497-511,共15页
This paper deals with the design and development of the observational system of geo-electrical resistivity on the basis of the demands for exploring the temporal variations of electrical properties of Earth media in t... This paper deals with the design and development of the observational system of geo-electrical resistivity on the basis of the demands for exploring the temporal variations of electrical properties of Earth media in the fixed points of the networks, which would be associated with the earthquake preparation. The observation system is characterized by the high accuracy in measurement, long term stability in operation and high level of rejection to the environmental interference. It consists of three main parts, configuration system measurement system, the calibration and inspection system. 展开更多
关键词 geo-electrical resistivity observation system earthquake monitoring configuration system measurement system calibration and inspection system
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The thermo-electric effect of magnetite and the mechanism of geo-electric abnormalities during earthquakes 被引量:2
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作者 Junfeng Shen Xuhui Shen +1 位作者 Qian Liu Na Ying 《Geoscience Frontiers》 SCIE CAS 2010年第1期99-104,共6页
The thermo-electric coefficients of twenty-six magnetite samples, formed either by magmatism or metamorphism, were tested by the thermo-electric instrument BHET -06. Results showed that the coef- ficient is of a const... The thermo-electric coefficients of twenty-six magnetite samples, formed either by magmatism or metamorphism, were tested by the thermo-electric instrument BHET -06. Results showed that the coef- ficient is of a constant value of about -0.05 mV/℃. It is emphasized that because every magnetite grain was tested randomly, the coefficient is independent of the crystallographic direction. This fact means the thermal voltage generated from a single magnetite crystal can be accumulated, and as a result a new thermo-electric field can arise when a gradient thermal field exists and is active within the earth's crust. Because magnetite is widespread in the earth's crust (generally appearing more in the middle-lower crust), there is more-thanrandom probability that the additional thermo-electric field can be generated when certain thermal conditions are fulfilled. We, therefore, used the thermo-electric effect of magnetite to study the mechanism responsible for the presence of abnormal geo-electric fields during earthquake formation and occurrence, because gradient thermal fields always exist before earthquakes. The possible presence of additional thermo-electric fields was calculated under theoretical seismological conditions, using the following calculation formula:E= - 0.159(σ×△T×Ф×ρ2×[[(h^2 - 2x^2)cos α + 3hxsin α]/ρ1 (h^2 +x^2)^5/2). In the above formula, σ is thermo-electric coefficient of magnetite, △T is the temperature difference acting on it, Ф is a sectional area on a block of magnetite vertically perpendicular to the direction of the thermal current, ρ1 and ρ2 are the respective resistivities of magnetite and the crust, and h, α, and x, respectively, h is the depth of embedded magnetite block. α means the angle created by the horizontal line and ligature of the two poles of magnetite block, and x is the distance from observation point to projective center point of the magnetite block on earth surface. According to simulations calculated with this formula, additional thermo-electric field intensity may reach as high as n to n × 10^2 mV/km. This field is strong enough to cause obvious anomalies in the background geo-electric field, and can be easy probed by earthquake monitoring equipment. Therefore, we hypothesize that geo-electric abnormalities which occur during earthquakes may be caused by the thermo-electric effect of magnetite. 展开更多
关键词 MAGNETITE Thermo-electric Earthquake Abnormal geo-electricity
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Analysis and Study on the Change of the Observed Geo-electric Field Data at Lhasa Geomagnetic Station before and after the Nepal MS8.1 Earthquake
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作者 Xi Jilou Guan Huaping +7 位作者 Liu Chao Zhuang Nan Guan Xinying Yang Xiaoming Zhang Zhiguo Ci Zhuoga Kelsang Drolma Ma Aiming 《Earthquake Research in China》 CSCD 2016年第4期526-541,共16页
In this paper,the main purpose is to analyze and research the characteristics of the geoelectric field observed data with a long time span and large amplitude abnormal change,at the Lhasa geomagnetic station( hereafte... In this paper,the main purpose is to analyze and research the characteristics of the geoelectric field observed data with a long time span and large amplitude abnormal change,at the Lhasa geomagnetic station( hereafter referred to as "Lhasa station "),before and after the Nepal M_S8. 1 strong earthquake,which occurred on April 25,2015. Based on the observation conditions,the observation system,and the observed data of Lhasa station preliminary discussed,the main characteristics of the abnormal change and evolution process are analyzed and studied,using the following two methods; the "synthesis energy accumulation"and the "power as MSA spectrum"analysis,from the two aspects of the"Time Domain"and"Frequency Domain. "The results show that the abnormal change of the geo-electric field observation of Lhasa station experienced a development stage following the process of "trend change- disturbance change- earthquake period-recovery period",and an evolution process of "low frequency change- high frequency change- smooth change- high frequency change ",before and after the Nepal M_S8. 1strong earthquake. Comprehensive analysis shows that the variation characteristics and evolution process of the geo-electric field at Lhasa station are basically consistent with the results of the relevant mechanism and phenomenon research. So far,this is valuable information with certain objectivity,which is typical and representative to reflect the whole process of the gestation, occurrence and complete development of such strongearthquakes. 展开更多
关键词 geo-electric field Nepal Ms8. 1 earthquake Lhasa geomagnetic station Abnormal change Synthesis energy accumulation Power as MSA spectrum
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Geo-electrical Investigation of Mullusi Aquifer, Rutba, Iraq
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作者 Abed Salih Al Dulaymi Emad Abdul Rahman Al-Heety Bayan Muhie Hussien 《International Journal of Geosciences》 2012年第3期549-564,共16页
The geophysical study was performed east of Rutba town due to vertical electrical sounding in a net of forty points between Dhalaa and Dhabaa valleys. Geophysical electrical model applicated using Winsev6 program to d... The geophysical study was performed east of Rutba town due to vertical electrical sounding in a net of forty points between Dhalaa and Dhabaa valleys. Geophysical electrical model applicated using Winsev6 program to determine the geo-electrical layers. Three geo-electrical layers were derived from geophysical survey. These layers are composed of four sediment types, such as clays, marls, marly carbonates, carbonates (dolomitic limestone), characterized by resistivity less than 20 ohm-m, 20 - 100 ohm-m, 100 - 350 ohm-m and more than 350 ohm-m, respectively. The thickness of the geo-electrical horizons are increased in Dhabaa Fault zone which characterized by multi karst shapes reflected as karst topography on the surface, which represents subsurface structural boundary for Mullusi aquifer, where this aquifer considered as main water supply for Rutba people in drinking water throughout 17 water wells located in Dhabaa site. Two empirical relation between Formation Factors (F) and Hydraulic Conductivity (K) obtained using linear and Polynomial regression techniques. The first equation of linear fit (F = 11.82 + 116.45 K;with a Correlation Coefficient of 0.94) represents the contribution between formation factor and hydraulic conductivity of a 2nd layer in Mullusi aquifer. The second equation of 3rd degree Polynomial Fit (F = 20.32 - 203.33 K + 1554.99 K2 -3127.30 K3;with a Correlation Coefficient of 0.75) represents the contribution between formation factor and hydraulic conductivity of a 3rd layer in Mullusi aquifer. 展开更多
关键词 geo-electrical LAYER HYDRAULIC CONDUCTIVITY Mullusi AQUIFER Iraq
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Geo-Electric Models of Primorski Krai, Russia
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作者 T.V.Selivanova O.S.Gorbulya 《Global Geology》 2002年第2期204-209,共6页
Based on the electrical properties and structural-tectonic principles, several geo-electric models have been established for the hydrogeologic provinces in Primorski Krai. They are mainly two-layered near-horizontally... Based on the electrical properties and structural-tectonic principles, several geo-electric models have been established for the hydrogeologic provinces in Primorski Krai. They are mainly two-layered near-horizontally-layered model with a high-resistivity underlying horizon, multiple-layered model with subhorizontal interfaces, model with an inclined interface and a pinching bed, and model with a local extended inclusion. And these models can provide good basin for searching for ground water in the region. 展开更多
关键词 Primorski Krai Hydrogeologic province geo-electric model Ground WATER
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Two-dimensional regularized inversion of AMT data based on rotation invariant of Central impedance tensor 被引量:4
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作者 XiaoZhong Tong JianXin Liu AiYong Li 《Earth and Planetary Physics》 2018年第5期430-437,共8页
Considering the uncertainty of the electrical axis for two-dimensional audo-magnetotelluric(AMT) data processing, an AMT inversion method with the Central impedance tensor was presented. First, we present a calculatio... Considering the uncertainty of the electrical axis for two-dimensional audo-magnetotelluric(AMT) data processing, an AMT inversion method with the Central impedance tensor was presented. First, we present a calculation expression of the Central impedance tensor in AMT, which can be considered as the arithmetic mean of TE-polarization mode and TM-polarization mode in the twodimensional geo-electrical model. Second, a least-squares iterative inversion algorithm is established, based on a smoothnessconstrained model, and an improved L-curve method is adopted to determine the best regularization parameters. We then test the above inversion method with synthetic data and field data. The test results show that this two-dimensional AMT inversion scheme for the responses of Central impedance is effective and can reconstruct reasonable two-dimensional subsurface resistivity structures. We conclude that the Central impedance tensor is a useful tool for two-dimensional inversion of AMT data. 展开更多
关键词 audio-magnetotelluric/AMT impedance tensor rotation invariants two-dimensional geo-electrical model regularized inversion
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Discussion on several important problems in earthquake-related electromagnetic disturbance monitoring in China
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作者 Lanwei Wang Shizhong Zhang Yu Zhang Dapeng Liu 《Earthquake Science》 CSCD 2011年第6期583-591,共9页
Earthquake-related electromagnetic observation aims at finding abnormal electromagnetic variation associated with earthquake possibly. The existing studies have proved that this method is, to a large extent, effective... Earthquake-related electromagnetic observation aims at finding abnormal electromagnetic variation associated with earthquake possibly. The existing studies have proved that this method is, to a large extent, effective in short-term and impending earthquake predication. This paper summarizes progress and discusses some related problems in this field. Some requirements for observation system have been proposed to improve monitoring level. As a case observation using the reformed observation system in Jinghai seismologie station, Tianjin, some results are given. 展开更多
关键词 earthquake-related electromagnetic disturbance geo-electric field magnetic field elec-tromagnetic disturbance event
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Hydro-Geoelectrical Investigation for the Potential of Underground Water Storage along the lower reaches of King Abdullah Canal-Deir Alla Area/Jordan
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作者 Hani Al-Amoush Elias Salameh Marwan Al-Raggad 《Journal of Water Resource and Protection》 2012年第7期545-559,共15页
In this article the potential stoarativity of groundwater in the alluvial deposits along the King Abdullah Canal (KAC) in Deir Alla-Sulikhat area is studied. In this study geological, geoelectrical and Hydro-geochemic... In this article the potential stoarativity of groundwater in the alluvial deposits along the King Abdullah Canal (KAC) in Deir Alla-Sulikhat area is studied. In this study geological, geoelectrical and Hydro-geochemical methods were used with the aim of storing some water of the Canal during water excess times in the underground to be extracted for use as drinking source for human during shortages in the Canal water and in emergency causes of Canal water pollution. The results show the existence of appropriate underground space in the alluvial deposits for water storage and that the water/ water and water/rock interactions are also be minimal and will not present and detriment to the different groundwater bodies. Implementing groundwater artificial recharge in the Jordan Valley area to create storage for King Abdullah Canal (KAC) water will enhance the drinking water supply during the dry season and it will also serve as a reserve for emergency causes, especially pollution accidents in King Abdullah Canal (KAC), such as those taking place almost every year. 展开更多
关键词 JORDAN VALLEY geo-electrical KING Abdullah CANAL (KAC)
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Model Design for AMT Data Inversion
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作者 Shancong Yao Ruliang Zhang +2 位作者 Baoqiang Qiao Hanping Wan Xiang Yu 《Open Journal of Geology》 2017年第3期420-428,共9页
By analyzing the characters of the mainstream commercial magnetotelluric inversion softwares in dealing with audio magnetotelluric data, a dynamic model-making method for inversion has been developed based on the obse... By analyzing the characters of the mainstream commercial magnetotelluric inversion softwares in dealing with audio magnetotelluric data, a dynamic model-making method for inversion has been developed based on the observed AMT data. This method focusing on model domain can adjust mesh’s scale and model’s dimension depending on the field data just with a few parameters. By this, it is convenient to study the geo-electrical anomalies variations of different scale or dimensional models. Applying such model-making technique into the known hardrock geological setting, it is easy to obtain a new geo-electrical model which agrees with the resistivity curves of core samples better than before. It is demonstrated that this can increase the recognition of the resistivity contrast and deserves studying further. 展开更多
关键词 AMT EXPLORATION Making-Model Based on AMT Data geo-electric STRUCTURE
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Application of Coefficient of Anisotropy to the Geophysical Prospecting of Campo—Ma’an Area of the Ntem Complex in Cameroon
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作者 Njingti-Nfor   Owona Angue Marie Louise +2 位作者 Kue Petou Rokis Malquaire Bisso Dieudonné Lando Tsakou Julyo Achille 《Open Journal of Geology》 2017年第12期1801-1818,共18页
Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determin... Audiomagnetotelluric data were acquired for 10 sounding stations in open fields and roads along the main highways from Campo to Ma’an in Cameroon. An application of the coefficients of anisotropy was used to determine the tectonic settings and the nature of the contacts between the sedimentary formation of the Kribi-Campo basin and the cratonic Ntem Complex. The results of this study show that apart from the sedimentary formation, the metamorphic formation in this area comprises two metamorphic blocks: a regional metamorphic block which might be igneous or granitic in nature and composition and seem to be Precambrian and plutonic in origin and a contact or transitional metamorphic block, which might represent schist or gneiss rocks. The contact or transitional metamorphic block might be as a result of a long period of contact between regional metamorphic rocks and rocks of sedimentary formation. These contact/transitional metamorphic rocks which are found sandwiched between rocks of sedimentary formation and rocks of the regional metamorphic block and at varied depths confirm the existence of vertical and sub-vertical contacts between the Kribi-Campo basin and the cratonic Ntem complex. Two types of rock contacts have been identified: a sedimentary-schist contact which is found at the boundary between the sedimentary formation and the transitional metamorphic block and a schist-granite contact between the transitional and regional metamorphic blocks. Two main formations: a sedimentary formation, which is found in the Kribi-Campo sub-basin and the Ntem River bed and its flood plains and the metamorphic formation which includes both the transitional and regional metamorphic rocks have also been identified in the area of study. Subsurface rocks and rock materials have been observed to be highly resistive and occupying almost the entire subsurface in the area of study confirming the high vertical tectonic stability of the Ntem Complex even at contact with the sedimentary Kribi-Campo basin. 展开更多
关键词 ANISOTROPY Telluric geo-electric SUBSIDENCE ISOTROPIC Vertical FAULTS TECTONICS
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Integrated Geophysical and Geotechnical Investigations for Earth Dam along Dansak River, Upper Shemankar River Basin, Jos Plateau, Central Nigeria
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作者 Longpia Cedric Bernard Dakwo Philip Datsok Pam Bulus Gwom 《Journal of Earth Science and Engineering》 2014年第8期470-483,共14页
A total of 60 VES (geo-electrical resistivity soundings) and ten exploratory core holes (boreholes) were carried out along the axis of a proposed earth dam site as part of an overall geotechnical investigation for... A total of 60 VES (geo-electrical resistivity soundings) and ten exploratory core holes (boreholes) were carried out along the axis of a proposed earth dam site as part of an overall geotechnical investigation for the design and construction of an earth dam along Dansak River, Shemankar River Basin, Jos Plateau, Nigeria. The geophysical interpretation revealed four to five geo-electric layers corresponding to lithologic units (1) topsoil from 0-2 m with a resistivity value of 〈 100-320 ohm-m, (2) weathered/slightly weathered basalt fi'om 0.6 m to 20 m characterized by resistivity value of 27-130 ohm-m, followed by (3) basalt/fractured basalts with resistivity value of 130-400 ohm-m and (4) the basement rocks with resistivity value 〉 320 ohm-m to 3,021 ohm-m. Exploratory borehole drilling encountered a series of lithologic units viz: overburden (clay, silt and sand) weathered basalt, slightly weathered basalt, fresh/fractured basalts, weathered migmatite and migmatites/migmatite gneiss. Exploratory core analysis in terms of CR (core recovery) and RQD (rock quality designation) revealed an average of 70%-90% and 75%-90%, respectively. Lugeon test gave Lugeon values of 1-5 for the ten core holes. However, fractures with Lugeon value from 〉 5-15 lugeon were encountered on borehole numbers BH 1, 7, 8, 9 and 10. Grouting is recommended to seal this shallow to medium depth (0-15 m) fractures to reduce or eliminate possible seepage when the dam is constructed. The rock mass index grading for the dam axis ranges from good to excellent. 展开更多
关键词 geo-electrical resistivity GEOTECHNICAL Dansak River rock quality designation rock mass index Lugeon test.
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Integrated Landsat Imagery and Geophysical Exploration for Groundwater Potential Evaluation of Okene and Its Environs, Southwestern Nigeria
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作者 John Olurotimi Amigun Richard Ajibola Faruwa Akinola Adesuji Komolafe 《International Journal of Geosciences》 2015年第3期209-229,共21页
In this study, an integrated remote sensing and geophysical (aeromagnetic and geo-electric) methods was employed to assess the potential of groundwater in a basement complex terrain of Okene and its environs, Southwes... In this study, an integrated remote sensing and geophysical (aeromagnetic and geo-electric) methods was employed to assess the potential of groundwater in a basement complex terrain of Okene and its environs, Southwestern, Nigeria. Landsat imagery acquired over the study area was processed in the Geographic Information Systems (GIS) environment to delineate the surface lineaments, drainage networks and their orientations. Aeromagnetic data over the area were analyzed and its derivative maps were interpreted to further map the structures and the geology in the subsurface;depths to magnetic sources were determined using spectral analysis. Vertical Electrical Sounding (VES) of geo-electric method was interpreted to map the subsurface geology layers. The results of the integrated data were correlated with borehole yield data of the area for effective interpretation. Delineated lineaments from the azimuth, frequency plot showed dominant trends in the NE-SW and NNE-SSW directions. Radial average power spectrum revealed the depth to magnetic sources between 100 and 2500 m and the interpreted VES data characterized the area into three to four subsurface layers. In correlating the results with borehole yield data, the zones with high lineament density and low/negative magnetic anomaly were categorized as high groundwater potential zones while areas with low lineament density and high/positive magnetic anomaly as low groundwater potential zones. This study will guide efficiently subsequent groundwater drilling program in the study area. 展开更多
关键词 GROUNDWATER BASEMENT Complex AEROMAGNETIC geo-electrics REMOTE Sensing GIS
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