Karst caves are widely distributed in southwest China, causing difficulties and disasters for tunnel construction. To better detect the krast caves in front of the tunnels under construction using the transient electromagnetic method, in this paper we propose a 3-D finite element method to simulate the multi-parameter transient electromagnetic response of unfavorable geological bodies in a whole-space. First, the models of vertical water-filled faults, water-filled caves and complex geological bodies in front of the tunnel face are established. The horizontal electric field component and the vertical magnetic field component at different time in the whole-space are researched. Secondly, the electromagnetic response features of the caves with different resistivity, buried depths and scales are studied. We found that the resistivity of the target body is 10 times larger than that of the surrounding rocks, and the anomaly amplitude increases obviously with the growing distance from the target body. The deeper the buried depth, the later the anomaly appears and the smaller the anomaly amplitude. The larger the target size, the longer the transient electromagnetic response delay and the larger the anomaly amplitude. We arranged a measuring line on the tunnel face. The full-time apparent resistivity section shows the position and characteristics of the low-resistivity anomalous body, indicating that the transient electromagnetic method (TEM) has obvious advantages in detecting the low-resistivity body in front of the tunnel face. Finally, the TEM is successfully applied to the advanced detection of a karst tunnel to get the electrical distribution of the surrounding rocks in front of the tunnel face. According to the geological conditions of the excavated tunnel, the validity of the TEM in the tunnel advanced prediction is verified.
{"title":"The Whole-Space Modeling of the Hazardous Geological Body ahead of the Tunnel Face by the Transient Electromagnetic Method","authors":"Hua-ming Li, Jifeng Zhang, Tian-xin Shang, Zhijian Hu, Yu Shi, Le-jun Cai, Ping Huang","doi":"10.32389/jeeg22-017","DOIUrl":"https://doi.org/10.32389/jeeg22-017","url":null,"abstract":"Karst caves are widely distributed in southwest China, causing difficulties and disasters for tunnel construction. To better detect the krast caves in front of the tunnels under construction using the transient electromagnetic method, in this paper we propose a 3-D finite element method to simulate the multi-parameter transient electromagnetic response of unfavorable geological bodies in a whole-space. First, the models of vertical water-filled faults, water-filled caves and complex geological bodies in front of the tunnel face are established. The horizontal electric field component and the vertical magnetic field component at different time in the whole-space are researched. Secondly, the electromagnetic response features of the caves with different resistivity, buried depths and scales are studied. We found that the resistivity of the target body is 10 times larger than that of the surrounding rocks, and the anomaly amplitude increases obviously with the growing distance from the target body. The deeper the buried depth, the later the anomaly appears and the smaller the anomaly amplitude. The larger the target size, the longer the transient electromagnetic response delay and the larger the anomaly amplitude. We arranged a measuring line on the tunnel face. The full-time apparent resistivity section shows the position and characteristics of the low-resistivity anomalous body, indicating that the transient electromagnetic method (TEM) has obvious advantages in detecting the low-resistivity body in front of the tunnel face. Finally, the TEM is successfully applied to the advanced detection of a karst tunnel to get the electrical distribution of the surrounding rocks in front of the tunnel face. According to the geological conditions of the excavated tunnel, the validity of the TEM in the tunnel advanced prediction is verified.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"11 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75374079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joint inversion of different geophysical methods is a powerful tool to overcome the limitations of individual inversions. Body wave tomography is used to obtain P-wave velocity models by inversion of P-wave travel times. Surface wave tomography is used to obtain S-wave velocity models through inversion of the dispersion curves data. Both methods have inherent limitations. We focus on the joint body and surface waves tomography inversion to reduce the limitations of each individual inversion. In our joint inversion scheme, the Poisson ratio was used as the link between P-wave and S-wave velocities, and the same geometry was imposed on the final velocity models. The joint inversion algorithm was applied to a 2D synthetic dataset and then to two 2D field datasets. We compare the obtained velocity models from individual inversions and the joint inversion. We show that the proposed joint inversion method not only produces superior velocity models but also generates physically more meaningful and accurate Poisson ratio models.
{"title":"Physically Constrained 2D Joint Inversion of Surface and Body Wave Tomography","authors":"M. Karimpour, E. Slob, L. Socco","doi":"10.32389/jeeg21-031","DOIUrl":"https://doi.org/10.32389/jeeg21-031","url":null,"abstract":"Joint inversion of different geophysical methods is a powerful tool to overcome the limitations of individual inversions. Body wave tomography is used to obtain P-wave velocity models by inversion of P-wave travel times. Surface wave tomography is used to obtain S-wave velocity models through inversion of the dispersion curves data. Both methods have inherent limitations. We focus on the joint body and surface waves tomography inversion to reduce the limitations of each individual inversion. In our joint inversion scheme, the Poisson ratio was used as the link between P-wave and S-wave velocities, and the same geometry was imposed on the final velocity models. The joint inversion algorithm was applied to a 2D synthetic dataset and then to two 2D field datasets. We compare the obtained velocity models from individual inversions and the joint inversion. We show that the proposed joint inversion method not only produces superior velocity models but also generates physically more meaningful and accurate Poisson ratio models.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"40 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72962152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Roadside MASW survey utilizes traffic-generated surface wave signals for subsurface characterization and, thus, can be a useful geophysical method, especially in urban areas. However, such signals originating from vehicular movements over road surface irregularities, or sources, produce complex field records of multi-source and multi-azimuthal characteristics. Such sources are termed intra-line if they exist within the receiver spread and outer-line when they exist outside the receiver spread. In a roadside survey, the receiver spread is placed outside and parallel to the centreline of the road, thereby creating an offline distance with respect to the sources on the road. In this study, experimental investigations are conducted to determine the influence of the presence of intra-line or outer-line sources and offline distances of source positioning on the dispersion imaging of roadside MASW records. Artificial hurdles were placed deliberately at different positions on an adjacent road to determine the influence of intra-line and outer-line sources. Furthermore, receiver arrays were placed at varying offline distances with respect to the centreline of the adjacent road to assess the effect of offline distance on the dispersion imaging and subsequent shear wave velocity profile. The study finds that the dispersion images obtained from the intra-line source have better resolutions compared to those obtained from the outer-line source. Further, the presence of multiple sources during the data acquisition does not necessarily shed any detrimental influence on dispersion imaging as long as there is no contamination and mutual interferences of the raw wavefield records. As the offline distance increases, the intensity of the traffic-generated source signal diminishes. It is observed typically for the studied site that beyond an offline distance of 15 m, there remains no recognizable energy to obtain a distinct dispersion image. A comparative study of the shear wave velocity profiles obtained from a borehole, roadside, active, and passive remote MASW surveys revealed an agreeable match, thereby indicating the usability of the roadside MASW survey, especially when offline distance is not enormously large.
{"title":"Subsurface Profiling Using Roadside MASW Survey: Influence of Multiple Sources and Offline Distance","authors":"D. Baglari, A. Dey, Jumrik Taipodia","doi":"10.32389/21-010","DOIUrl":"https://doi.org/10.32389/21-010","url":null,"abstract":"Roadside MASW survey utilizes traffic-generated surface wave signals for subsurface characterization and, thus, can be a useful geophysical method, especially in urban areas. However, such signals originating from vehicular movements over road surface irregularities, or sources, produce complex field records of multi-source and multi-azimuthal characteristics. Such sources are termed intra-line if they exist within the receiver spread and outer-line when they exist outside the receiver spread. In a roadside survey, the receiver spread is placed outside and parallel to the centreline of the road, thereby creating an offline distance with respect to the sources on the road. In this study, experimental investigations are conducted to determine the influence of the presence of intra-line or outer-line sources and offline distances of source positioning on the dispersion imaging of roadside MASW records. Artificial hurdles were placed deliberately at different positions on an adjacent road to determine the influence of intra-line and outer-line sources. Furthermore, receiver arrays were placed at varying offline distances with respect to the centreline of the adjacent road to assess the effect of offline distance on the dispersion imaging and subsequent shear wave velocity profile. The study finds that the dispersion images obtained from the intra-line source have better resolutions compared to those obtained from the outer-line source. Further, the presence of multiple sources during the data acquisition does not necessarily shed any detrimental influence on dispersion imaging as long as there is no contamination and mutual interferences of the raw wavefield records. As the offline distance increases, the intensity of the traffic-generated source signal diminishes. It is observed typically for the studied site that beyond an offline distance of 15 m, there remains no recognizable energy to obtain a distinct dispersion image. A comparative study of the shear wave velocity profiles obtained from a borehole, roadside, active, and passive remote MASW surveys revealed an agreeable match, thereby indicating the usability of the roadside MASW survey, especially when offline distance is not enormously large.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"67 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85730951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhihai Jiang, Wenchuang Wang, Gongjin Zang, Zhaotao Yan
In reality, the spatial distribution of geological anomalies is extremely complex. In the process of numerical simulation of transient electromagnetic method, limited to the modeling level, regular sphere, cylinder, cuboid and other simple models are often used to replace the complex actual geological model. As a result, there is a large deviation between the numerical simulation results and the real transient electromagnetic response of the actual geological model, which affects the reliability of the data interpretation. In order to solve the problem of transient electromagnetic numerical simulation of complex geoelectric model, we established complex geological anomalies model based on a variety of modeling platforms, and integrated the spatial combination information of nodes, lines and surfaces of the model with the spatial information of the observation system. Then gained the unstructured mesh discrete space of the integrated model according to the Delaunay tetrahedral subdivision principle. Finally, we realized the simulation of the transient electromagnetic responses of ultra-complex models by using vector finite element method.
{"title":"Ultra-complex Geological Anomalies Modeling on Transient Electromagnetic Response","authors":"Zhihai Jiang, Wenchuang Wang, Gongjin Zang, Zhaotao Yan","doi":"10.32389/jeeg22-010","DOIUrl":"https://doi.org/10.32389/jeeg22-010","url":null,"abstract":"In reality, the spatial distribution of geological anomalies is extremely complex. In the process of numerical simulation of transient electromagnetic method, limited to the modeling level, regular sphere, cylinder, cuboid and other simple models are often used to replace the complex actual geological model. As a result, there is a large deviation between the numerical simulation results and the real transient electromagnetic response of the actual geological model, which affects the reliability of the data interpretation. In order to solve the problem of transient electromagnetic numerical simulation of complex geoelectric model, we established complex geological anomalies model based on a variety of modeling platforms, and integrated the spatial combination information of nodes, lines and surfaces of the model with the spatial information of the observation system. Then gained the unstructured mesh discrete space of the integrated model according to the Delaunay tetrahedral subdivision principle. Finally, we realized the simulation of the transient electromagnetic responses of ultra-complex models by using vector finite element method.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"34 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82615438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Persova, Y. Soloveichik, D. Vagin, A. P. Sivenkova, A. S. Kiseleva, D. S. Kiselev, M. G. Tokareva
We present two approaches to solving the airborne electromagnetic (AEM) problems given the induced polarization (IP) effect: with calculating the field in a polarizable medium directly in the time domain (TD) and with calculating the EM+IP field in the frequency domain (FD) followed by a transition to the time domain. The first approach is based on calculating the field at each time step given the sources that depend on the currents excited in the medium at previous time steps. This approach allows us to use any IP decay functions. The frequency domain approach is based on the Fourier series expansion of a non-stationary source and the Cole-Cole model. In order to reduce the computational cost, we use the Hermite spline interpolation. Both approaches allow modeling EM + IP processes in complex media with topography and the curved boundaries of layers containing 3D heterogeneities. 3D modeling is performed on non-conforming hexahedral meshes generated fully automatically. The analysis of computational efficiency and verification of the developed approaches are presented in comparison with the results from other researchers. Moreover, we compare the results obtained in the time and frequency domains. The results of 3D modeling the IP effects, which are obtained for some geoelectrical models typical for AEM exploration problems, are demonstrated.
{"title":"3D Modeling of Time-domain AEM Fields with IP Effect in Complex Media with Topography","authors":"M. Persova, Y. Soloveichik, D. Vagin, A. P. Sivenkova, A. S. Kiseleva, D. S. Kiselev, M. G. Tokareva","doi":"10.32389/jeeg21-027","DOIUrl":"https://doi.org/10.32389/jeeg21-027","url":null,"abstract":"We present two approaches to solving the airborne electromagnetic (AEM) problems given the induced polarization (IP) effect: with calculating the field in a polarizable medium directly in the time domain (TD) and with calculating the EM+IP field in the frequency domain (FD) followed by a transition to the time domain. The first approach is based on calculating the field at each time step given the sources that depend on the currents excited in the medium at previous time steps. This approach allows us to use any IP decay functions. The frequency domain approach is based on the Fourier series expansion of a non-stationary source and the Cole-Cole model. In order to reduce the computational cost, we use the Hermite spline interpolation. Both approaches allow modeling EM + IP processes in complex media with topography and the curved boundaries of layers containing 3D heterogeneities. 3D modeling is performed on non-conforming hexahedral meshes generated fully automatically. The analysis of computational efficiency and verification of the developed approaches are presented in comparison with the results from other researchers. Moreover, we compare the results obtained in the time and frequency domains. The results of 3D modeling the IP effects, which are obtained for some geoelectrical models typical for AEM exploration problems, are demonstrated.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"20 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89928429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Standoff electromagnetic induction (EMI) measurements of complex conductivity and complex permittivity for engineering soil properties have the potential to revolutionize the way the US Army handles route planning and infrastructure assessment. An unmanned aerial system (UAS) based EM platform for soil interrogation would have wide reaching impact in a variety of applications including: civil infrastructure inspection, in-theater ingress and egress routing, reduction of false positives in IED detection, and permafrost mapping, among many others. Traditional frequency domain EMI instruments assess conductivity at low-frequencies, generally in the range of 1–20 kHz; however, recent advancements have resulted in instrumentation targeting a broadband range of frequencies, from 10 kHz through 20 MHz. This advancement, known as high-frequency electromagnetic induction (HFEMI) allows the potential to evaluate frequency domain relaxation effects in soils by acquiring both the in phase and quadrature response of the secondary field from the soil. Relaxation phenomena such as induced polarization and dielectric permittivity are related to important soil properties that can potentially be exploited using this HFEMI system. While conductivity measurements using the quadrature component of the EMI response are well established in EMI instrumentation, understanding of the relationship between direct electrical measurements and standoff HFEMI measurements is lacking. In an effort to illuminate this relationship between various electrical and electromagnetic methods at a scale suitable for soil property estimation, we perform side-by-side measurements using galvanic geoelectrical methods (ERT, IP), electromagnetics, time-domain reflectometry (TDR) and ground penetrating radar (GPR). We compare HFEMI obtained quadrature and in-phase responses to ERT, IP, TDR and GPR measurements. A tank-scale test cell was developed for comparison of the above methods and allowed assessment of sand at varying saturation levels. Further, the HFEMI response at varying heights above the sand surface was also assessed. Qualitative observations are reported in an initial attempt to relate the HFEMI response to important soil parameters.
{"title":"Standoff High-Frequency Electromagnetic Induction Response of Unsaturated Sands: A Tank-Scale Feasibility Study","authors":"D. Glaser, F. Shubitidze, B. Barrowes","doi":"10.32389/jeeg21-030","DOIUrl":"https://doi.org/10.32389/jeeg21-030","url":null,"abstract":"Standoff electromagnetic induction (EMI) measurements of complex conductivity and complex permittivity for engineering soil properties have the potential to revolutionize the way the US Army handles route planning and infrastructure assessment. An unmanned aerial system (UAS) based EM platform for soil interrogation would have wide reaching impact in a variety of applications including: civil infrastructure inspection, in-theater ingress and egress routing, reduction of false positives in IED detection, and permafrost mapping, among many others. Traditional frequency domain EMI instruments assess conductivity at low-frequencies, generally in the range of 1–20 kHz; however, recent advancements have resulted in instrumentation targeting a broadband range of frequencies, from 10 kHz through 20 MHz. This advancement, known as high-frequency electromagnetic induction (HFEMI) allows the potential to evaluate frequency domain relaxation effects in soils by acquiring both the in phase and quadrature response of the secondary field from the soil. Relaxation phenomena such as induced polarization and dielectric permittivity are related to important soil properties that can potentially be exploited using this HFEMI system. While conductivity measurements using the quadrature component of the EMI response are well established in EMI instrumentation, understanding of the relationship between direct electrical measurements and standoff HFEMI measurements is lacking. In an effort to illuminate this relationship between various electrical and electromagnetic methods at a scale suitable for soil property estimation, we perform side-by-side measurements using galvanic geoelectrical methods (ERT, IP), electromagnetics, time-domain reflectometry (TDR) and ground penetrating radar (GPR). We compare HFEMI obtained quadrature and in-phase responses to ERT, IP, TDR and GPR measurements. A tank-scale test cell was developed for comparison of the above methods and allowed assessment of sand at varying saturation levels. Further, the HFEMI response at varying heights above the sand surface was also assessed. Qualitative observations are reported in an initial attempt to relate the HFEMI response to important soil parameters.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"31 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75259391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Hu, Mei Liu, Yaxun Wang, Maosheng Ye, Shengxuan Li
Reservoir leakage can cause a waste of precious water resources and even severe environmental consequences. In this study, we use continuous resistivity profiling to evaluate the leakage problem of the Shuangwangcheng reservoir along the east route of the South-to-North Water Diversion Project. A numerical example was first built to validate the method's effectiveness in a saline aquifer environment. Thirty-five waterborne survey lines were then conducted with a total length of 74 km, and two ground survey lines had a length of 1.27 km each. We evaluated the quality of the overall data with the apparent resistivity of intersection points. Based on ground survey results, the resistivity value larger than 2 Ω.m at the bottom of the reservoir is regarded as leakage areas. Therefore, we divide resistivity survey results into three zones: freshwater reservoir, leakage zone, and saline aquifer. The distribution of freshwater intrusion is evaluated by fence diagram and interpolated horizontal resistivity contour maps. The delineated leakage zone is consistent with the lack of a low permeable loam layer on the north and east parts of the reservoir. The results prove that the waterborne resistivity survey method can efficiently and effectively assess leakage distribution inside a reservoir.
{"title":"Geophysical Assessment of Freshwater Intrusion into Saline Aquifers Beneath Plain Reservoirs","authors":"Z. Hu, Mei Liu, Yaxun Wang, Maosheng Ye, Shengxuan Li","doi":"10.32389/jeeg21-012","DOIUrl":"https://doi.org/10.32389/jeeg21-012","url":null,"abstract":"Reservoir leakage can cause a waste of precious water resources and even severe environmental consequences. In this study, we use continuous resistivity profiling to evaluate the leakage problem of the Shuangwangcheng reservoir along the east route of the South-to-North Water Diversion Project. A numerical example was first built to validate the method's effectiveness in a saline aquifer environment. Thirty-five waterborne survey lines were then conducted with a total length of 74 km, and two ground survey lines had a length of 1.27 km each. We evaluated the quality of the overall data with the apparent resistivity of intersection points. Based on ground survey results, the resistivity value larger than 2 Ω.m at the bottom of the reservoir is regarded as leakage areas. Therefore, we divide resistivity survey results into three zones: freshwater reservoir, leakage zone, and saline aquifer. The distribution of freshwater intrusion is evaluated by fence diagram and interpolated horizontal resistivity contour maps. The delineated leakage zone is consistent with the lack of a low permeable loam layer on the north and east parts of the reservoir. The results prove that the waterborne resistivity survey method can efficiently and effectively assess leakage distribution inside a reservoir.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"29 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81475022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Costard, T. Wunderlich, Katja Grüneberg-Wehner, F. Wolf, E. Erkul, M. Gräber, W. Rabbel
Manors are an important component of the cultural-economic history of Northern Germany and Southern Scandinavia. We present the results of a geophysical prospection that led to the identification of a previously unknown manor near the village of Noer, Schleswig-Holstein, Northern Germany. Although magnetic gradiometry provides a fast way to cover large areas, it does not provide accurate depth estimates, is affected by magnetic blanking and is unable to detect differences in water content. Therefore, we applied a combination of different geophysical methods to optimize the non-invasive reconstruction of the target and its surroundings not only with respect to building structures but also in relation to the surrounding landscape. In particular, a combination of magnetics, ground-penetrating radar (GPR), electromagnetic induction (EMI), electrical resistivity tomography (ERT), and soil samples were carried out to determine: (1) the object's exact location; (2) the building structure and state of preservation; and (3) any additional structures in the surrounding area. We detected a tripartite building of 22 by 27 m, with several inner walls, which was located underneath a topographic high on the surveyed field. The bulk structure is identifiable most clearly in the magnetic and EMI inphase component maps. GPR profiles and soil samples indicate flooring or foundations in part of the building. Their shallow depths of less than 2 m below the surface and debris clusters close to the surface indicate at least partial demolition. A surrounding wall was found about 5 m outside the building. The area in between shows no magnetic anomalies, lower resistivities in EMI and ERT, and low GPR reflection amplitudes. Soil samples suggest a moat or other water feature. Archaeological artifacts found at the location characterize the building as a 16th to 17th century brick manor. Other objects, like a suspected farmyard and access path could not be found. A comparison with historical sources suggest that the mansion is in relation to the manor Grönwohld. After a change of the owner it was degraded to a Meierhof, and subsequently the building decayed and was forgotten.
{"title":"The Deserted Manor of Noer, Schleswig-Holstein, Germany. Geophysical Prospection Methods in Comparison","authors":"L. Costard, T. Wunderlich, Katja Grüneberg-Wehner, F. Wolf, E. Erkul, M. Gräber, W. Rabbel","doi":"10.32389/jeeg21-023","DOIUrl":"https://doi.org/10.32389/jeeg21-023","url":null,"abstract":"Manors are an important component of the cultural-economic history of Northern Germany and Southern Scandinavia. We present the results of a geophysical prospection that led to the identification of a previously unknown manor near the village of Noer, Schleswig-Holstein, Northern Germany. Although magnetic gradiometry provides a fast way to cover large areas, it does not provide accurate depth estimates, is affected by magnetic blanking and is unable to detect differences in water content. Therefore, we applied a combination of different geophysical methods to optimize the non-invasive reconstruction of the target and its surroundings not only with respect to building structures but also in relation to the surrounding landscape. In particular, a combination of magnetics, ground-penetrating radar (GPR), electromagnetic induction (EMI), electrical resistivity tomography (ERT), and soil samples were carried out to determine: (1) the object's exact location; (2) the building structure and state of preservation; and (3) any additional structures in the surrounding area. We detected a tripartite building of 22 by 27 m, with several inner walls, which was located underneath a topographic high on the surveyed field. The bulk structure is identifiable most clearly in the magnetic and EMI inphase component maps. GPR profiles and soil samples indicate flooring or foundations in part of the building. Their shallow depths of less than 2 m below the surface and debris clusters close to the surface indicate at least partial demolition. A surrounding wall was found about 5 m outside the building. The area in between shows no magnetic anomalies, lower resistivities in EMI and ERT, and low GPR reflection amplitudes. Soil samples suggest a moat or other water feature. Archaeological artifacts found at the location characterize the building as a 16th to 17th century brick manor. Other objects, like a suspected farmyard and access path could not be found. A comparison with historical sources suggest that the mansion is in relation to the manor Grönwohld. After a change of the owner it was degraded to a Meierhof, and subsequently the building decayed and was forgotten.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"30 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75759853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Baoqing Tian, X. Lei, Huazhong Jiang, Chenlu Xu, Mingpeng Song
Geothermal resources are a clean and renewable energy source that can play a critical role in drastically reducing air pollution. The utilization of geothermal resources requires technical support to decrease the developing risk by applying an integrated interpretation of geophysical methods. In this study, we used geophysical methods in the Langfang region of China to design a workflow for the safe yield of geothermal resources. To do so, we conducted controlled-source audio-frequency magnetotelluric (CSAMT) soundings, shallow soil temperature surveys, radon gas measurements, and the microtremor survey method (MSM) at the geothermal exploration and development site. These geophysical analyses identified a geothermal reservoir and a buried channel in the region. The dominant fault developing in the area was identified as the best channel for heat and water based on the developed geothermal wells. In areas with relatively little geothermal exploration, this study provides a reference and demonstration for geothermal development.
{"title":"Multi-Method Geophysical Mapping of a Geothermal Reservoir and Buried Channel in Langfang, Northern Part of China","authors":"Baoqing Tian, X. Lei, Huazhong Jiang, Chenlu Xu, Mingpeng Song","doi":"10.32389/jeeg20-068","DOIUrl":"https://doi.org/10.32389/jeeg20-068","url":null,"abstract":"Geothermal resources are a clean and renewable energy source that can play a critical role in drastically reducing air pollution. The utilization of geothermal resources requires technical support to decrease the developing risk by applying an integrated interpretation of geophysical methods. In this study, we used geophysical methods in the Langfang region of China to design a workflow for the safe yield of geothermal resources. To do so, we conducted controlled-source audio-frequency magnetotelluric (CSAMT) soundings, shallow soil temperature surveys, radon gas measurements, and the microtremor survey method (MSM) at the geothermal exploration and development site. These geophysical analyses identified a geothermal reservoir and a buried channel in the region. The dominant fault developing in the area was identified as the best channel for heat and water based on the developed geothermal wells. In areas with relatively little geothermal exploration, this study provides a reference and demonstration for geothermal development.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83107695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A dryland critical-zone observatory is planned on a piedmont setting of the Jornada Experimental Range northeast of Las Cruces, New Mexico, near a ∼10-yr eddy flux covariance tower and vegetation monitoring experiment and a 2-yr old water-uptake rainfall infiltration experiment. We carried out several geophysical surveys to help select sites that minimize geologic complexity for follow up hydrologic and biogeochemical studies that will be conducted by other researchers. First, we conducted a review of regional topography, gravity, and magnetics prior to a site visit and then collected reconnaissance magnetic and electromagnetic data to aid in planning more detailed geophysical site characterization surveys. Our initial topographic analysis using 1/3 arc-second digital elevation models (DEMs) showed the proposed area had an out-of-equilibrium curvature pointing to active erosion and possible faulting. Short-wavelength step-like topographic anomalies in the DEMs were confirmed in LiDAR elevations, and are consistent with erosionally resistant soil horizons in the old alluvial fan deposits. Comparison of 2-D density and susceptibility models based on nearby (3-8 km) hydrostratigraphic studies established that the observed regional gravity and magnetic anomalies were larger than could be modeled with the 2-D structural constraints, and established the station spacing our reconnaissance surveys would require to sample shallow soil variations. Our first site visit confirmed the general fault locations and we identified three outcropping caliche horizons distinct to alluvial channel, proximal splay and distal splay deposits in a several hundred-meter traverse that are consistent with the short-wavelength topographic features. In order to plan additional seismic, radar, gravity, and electrical surveys within a region of such high potential variability, we collected magnetic field and magnetic susceptibility measurements along two profiles at 10-50 m spacing. We found anomalies consistent with two projected faults, as well as other bedrock structures, a result significantly more complex than prior regional hydrostratigraphic mapping had suggested. We also conducted a more limited 0.5 km long ground conductivity survey with 5 m spacing that traversed the rainfall infiltration experiment site and found anomalies that aligned with one of the projected faults. The results showed deep (>6 m) 50 mS/m (milliSiemens/meter) values, indicating moister soils, on the footwall side, dropping to 20 mS/m after crossing the fault, consistent with previous observations that normal faults in the Rio Grande Valley asymmetrically influence fluid flow.
计划在新墨西哥州拉斯克鲁塞斯东北部Jornada实验范围的山前设置一个旱地临界区观测站，靠近一个约10年的涡流通量相关塔和植被监测实验以及一个2年的吸水量降雨入渗实验。我们进行了几次地球物理调查，以帮助选择地质复杂性最小的地点，以便其他研究人员进行后续的水文和生物地球化学研究。首先，在实地考察之前，我们对区域地形、重力和磁学进行了回顾，然后收集了侦察磁和电磁数据，以帮助规划更详细的地球物理场地特征调查。我们使用1/3弧秒数字高程模型(dem)进行的初步地形分析显示，拟建区域有一个不平衡的曲率，指向活跃的侵蚀和可能的断层。在LiDAR高程中证实了dem的短波长阶梯状地形异常，并且与旧冲积扇沉积物的抗侵蚀土壤层位一致。基于邻近(3-8 km)水文地层研究的二维密度和敏感性模型的对比表明，观测到的区域重磁异常比二维结构约束所能模拟的要大，并确定了我们的侦察调查需要采样浅层土壤变化的站间距。我们的第一次实地考察确认了一般的断层位置，并在数百米的横截面上确定了三个不同于冲积河道，近展斜和远展斜矿床的露头层，这与短波长的地形特征相一致。为了在这样一个高电位变异性的区域内规划更多的地震、雷达、重力和电测量，我们沿着10-50米的两条剖面收集了磁场和磁化率测量数据。我们发现了与两条预测断层以及其他基岩结构一致的异常，结果比之前的区域水文地层填图所显示的要复杂得多。我们还进行了一个更有限的0.5 km长的地面电导率调查，间隔5 m，穿越降雨入渗实验场地，发现了与预测断层之一对齐的异常。结果显示，深部(>6 m) 50 mS/m(毫西门/米)，表明下盘土壤较湿润，穿过断层后降至20 mS/m，这与以往的观测结果一致，即里奥格兰德河谷正断层不对称影响流体流动。
{"title":"Geophysical Reconnaissance for Siting Dryland Critical-Zone Monitoring Experiments in Southern New Mexico, USA","authors":"D. Doser, M. Baker","doi":"10.32389/jeeg21-022","DOIUrl":"https://doi.org/10.32389/jeeg21-022","url":null,"abstract":"A dryland critical-zone observatory is planned on a piedmont setting of the Jornada Experimental Range northeast of Las Cruces, New Mexico, near a ∼10-yr eddy flux covariance tower and vegetation monitoring experiment and a 2-yr old water-uptake rainfall infiltration experiment. We carried out several geophysical surveys to help select sites that minimize geologic complexity for follow up hydrologic and biogeochemical studies that will be conducted by other researchers. First, we conducted a review of regional topography, gravity, and magnetics prior to a site visit and then collected reconnaissance magnetic and electromagnetic data to aid in planning more detailed geophysical site characterization surveys. Our initial topographic analysis using 1/3 arc-second digital elevation models (DEMs) showed the proposed area had an out-of-equilibrium curvature pointing to active erosion and possible faulting. Short-wavelength step-like topographic anomalies in the DEMs were confirmed in LiDAR elevations, and are consistent with erosionally resistant soil horizons in the old alluvial fan deposits. Comparison of 2-D density and susceptibility models based on nearby (3-8 km) hydrostratigraphic studies established that the observed regional gravity and magnetic anomalies were larger than could be modeled with the 2-D structural constraints, and established the station spacing our reconnaissance surveys would require to sample shallow soil variations. Our first site visit confirmed the general fault locations and we identified three outcropping caliche horizons distinct to alluvial channel, proximal splay and distal splay deposits in a several hundred-meter traverse that are consistent with the short-wavelength topographic features. In order to plan additional seismic, radar, gravity, and electrical surveys within a region of such high potential variability, we collected magnetic field and magnetic susceptibility measurements along two profiles at 10-50 m spacing. We found anomalies consistent with two projected faults, as well as other bedrock structures, a result significantly more complex than prior regional hydrostratigraphic mapping had suggested. We also conducted a more limited 0.5 km long ground conductivity survey with 5 m spacing that traversed the rainfall infiltration experiment site and found anomalies that aligned with one of the projected faults. The results showed deep (>6 m) 50 mS/m (milliSiemens/meter) values, indicating moister soils, on the footwall side, dropping to 20 mS/m after crossing the fault, consistent with previous observations that normal faults in the Rio Grande Valley asymmetrically influence fluid flow.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"7 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74873478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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