Abstract Numerical modelling of Ground Penetrating Radar (GPR) has been widely used for predicting and assessing its performance. Since the transmitter and the receiver are the most essential components of a GPR system, an accurate representation of them should be included in a model. Simulating a real system is particularly challenging, especially when it comes to commercial GPR systems. A three‐dimensional model based on a 2000 MHz “palm” antenna from Geophysical Survey Systems, Inc. (GSSI) is presented in this paper. The geometric features of the transducers were modelled via visual inspection while their unknown dielectric properties were estimated using global optimisers in order to minimise the differences between real and synthetic measurements. In particular, the antenna was calibrated in free space and on top of a metal plate. Subsequently, the resulting model was successfully tested in various case studies to assess its performance. Models of two units of the same transducer were developed, showing that units of the same system in general are not identical. The results, support the premise that global optimisers can be used to provide information on key aspects of the dielectric structure of the transducer and allow us to accurately model its behaviour in various environments. This article is protected by copyright. All rights reserved
{"title":"Developing a Realistic Numerical Equivalent of a GPR Antenna Transducer Using Global Optimisers","authors":"Ourania Patsia, Antonios Giannopoulos, Iraklis Giannakis","doi":"10.1002/nsg.12280","DOIUrl":"https://doi.org/10.1002/nsg.12280","url":null,"abstract":"Abstract Numerical modelling of Ground Penetrating Radar (GPR) has been widely used for predicting and assessing its performance. Since the transmitter and the receiver are the most essential components of a GPR system, an accurate representation of them should be included in a model. Simulating a real system is particularly challenging, especially when it comes to commercial GPR systems. A three‐dimensional model based on a 2000 MHz “palm” antenna from Geophysical Survey Systems, Inc. (GSSI) is presented in this paper. The geometric features of the transducers were modelled via visual inspection while their unknown dielectric properties were estimated using global optimisers in order to minimise the differences between real and synthetic measurements. In particular, the antenna was calibrated in free space and on top of a metal plate. Subsequently, the resulting model was successfully tested in various case studies to assess its performance. Models of two units of the same transducer were developed, showing that units of the same system in general are not identical. The results, support the premise that global optimisers can be used to provide information on key aspects of the dielectric structure of the transducer and allow us to accurately model its behaviour in various environments. This article is protected by copyright. All rights reserved","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135218420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Matthew John Couchman, Brian Barrett, Asger Eriksen
Abstract Ground penetrating radar (GPR) is a commonly used tool for railway trackbed inspection due to its ability to collect information about subsurface materials at high resolution and high speed. Although GPR recording systems allow for the collection of vast quantities of data (hundreds of kilometres per day), accurate ground truth information is difficult to obtain. Models of trackbed can be used to generate synthetic radargrams to provide a better understanding and predictability of GPR responses to a wide range of trackbed conditions. In this research, we produced models of ballast using randomly shaped 3D particles, with a range of particle size distributions to represent various stages of ballast breakdown. Additionally, void spaces are partially filled with a constant dielectric material to represent ballast contamination. We used gprMax to simulate the GPR response for a 2 GHz horn antenna over the trackbed models. These simulations resulted in radargrams that are visually indistinct from real recorded data in known conditions. These radargrams, along with their formative models, have provided valuable insights into how variations in trackbed conditions can impact GPR data.
{"title":"Synthetic modelling of railway trackbed for improved understanding of ground penetrating radar responses due to varying conditions","authors":"Matthew John Couchman, Brian Barrett, Asger Eriksen","doi":"10.1002/nsg.12272","DOIUrl":"https://doi.org/10.1002/nsg.12272","url":null,"abstract":"Abstract Ground penetrating radar (GPR) is a commonly used tool for railway trackbed inspection due to its ability to collect information about subsurface materials at high resolution and high speed. Although GPR recording systems allow for the collection of vast quantities of data (hundreds of kilometres per day), accurate ground truth information is difficult to obtain. Models of trackbed can be used to generate synthetic radargrams to provide a better understanding and predictability of GPR responses to a wide range of trackbed conditions. In this research, we produced models of ballast using randomly shaped 3D particles, with a range of particle size distributions to represent various stages of ballast breakdown. Additionally, void spaces are partially filled with a constant dielectric material to represent ballast contamination. We used gprMax to simulate the GPR response for a 2 GHz horn antenna over the trackbed models. These simulations resulted in radargrams that are visually indistinct from real recorded data in known conditions. These radargrams, along with their formative models, have provided valuable insights into how variations in trackbed conditions can impact GPR data.","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Ground penetrating radar (GPR) technology is widely used in tunnel engineering detection. however, various factors, such as environmental interference and low signal‐to‐noise ratio characteristics of the echo data, limit the detection accuracy. A noise and interference suppression algorithm based on improved singular value decomposition is proposed in this paper. Compared with traditional filtering methods, the proposed method has the advantages of thorough denoising, no clutter, efficient improvement of profile resolution, and less dependence on parameters. The main features of the proposed algorithm are as follows: (1) Given the global characteristics of the noise disturbance on the signal space, the minimum mean square error (MMSE) estimation is employed to approximate the effective signal, introducing the correction factor to suppress the larger singular value from the noise output in the reconstructing process of the effective signal subspace, and to eliminate the strong direct wave interference to avoid producing false signals. (2) A positive difference sequence search algorithm (PDS) based on rank order variance, as well as the method of selecting correction factors are proposed to improve the processing accuracy. In order to verify the design, the tunnel lining simulation model and the actual tunnel lining detection data are used. The results show good performance for noise and interference suppression, providing technical support for improving GPR data quality and tunnel detection accuracy. This article is protected by copyright. All rights reserved
{"title":"Noise reduction algorithm of gpr data based on mmse‐pds","authors":"Dejun Ma, Meng Fan, Xianlei Xu, Baode Fan","doi":"10.1002/nsg.12279","DOIUrl":"https://doi.org/10.1002/nsg.12279","url":null,"abstract":"Abstract Ground penetrating radar (GPR) technology is widely used in tunnel engineering detection. however, various factors, such as environmental interference and low signal‐to‐noise ratio characteristics of the echo data, limit the detection accuracy. A noise and interference suppression algorithm based on improved singular value decomposition is proposed in this paper. Compared with traditional filtering methods, the proposed method has the advantages of thorough denoising, no clutter, efficient improvement of profile resolution, and less dependence on parameters. The main features of the proposed algorithm are as follows: (1) Given the global characteristics of the noise disturbance on the signal space, the minimum mean square error (MMSE) estimation is employed to approximate the effective signal, introducing the correction factor to suppress the larger singular value from the noise output in the reconstructing process of the effective signal subspace, and to eliminate the strong direct wave interference to avoid producing false signals. (2) A positive difference sequence search algorithm (PDS) based on rank order variance, as well as the method of selecting correction factors are proposed to improve the processing accuracy. In order to verify the design, the tunnel lining simulation model and the actual tunnel lining detection data are used. The results show good performance for noise and interference suppression, providing technical support for improving GPR data quality and tunnel detection accuracy. This article is protected by copyright. All rights reserved","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136079760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seismic interferometry (SI) retrieves the Green's function between two receiver locations using their recordings from a boundary of sources. When using sources and receivers only at the surface, the virtual‐source gathers retrieved by SI contain pseudo‐physical reflections as well as ghost (non‐physical) reflections. These ghost reflections are the results of the cross‐correlation or auto‐correlation of primary reflections from two different depth levels, and they contain information about the seismic properties of specific layers in the subsurface. We investigated the application of ghost reflections for layer‐specific characterisation of the shallow subsurface using SI by auto‐correlation. First, we showed the technique's potential using synthetic data for a subsurface model with a lateral change in velocity, a gradient in depth for velocity, a thickness change, and a velocity change of the target layer. Then, we applied the technique to shallow subsurface field data. We also focused on improving the retrieval of ghost reflections by removing the free‐surface multiples and muting undesired events in active‐source gathers before applying SI. Our results demonstrate that the ghost reflections can be used advantageously to characterise the layer that causes them to appear in the results of SI. Consequently, they can also provide valuable information for imaging and monitoring shallow subsurface structures.This article is protected by copyright. All rights reserved
{"title":"The utilisation of ghost reflections retrieved by seismic interferometry for layer‐specific characterisation of the shallow subsurface","authors":"Faezeh Shirmohammadi, Deyan Draganov, Ranajit Ghose","doi":"10.1002/nsg.12275","DOIUrl":"https://doi.org/10.1002/nsg.12275","url":null,"abstract":"Seismic interferometry (SI) retrieves the Green's function between two receiver locations using their recordings from a boundary of sources. When using sources and receivers only at the surface, the virtual‐source gathers retrieved by SI contain pseudo‐physical reflections as well as ghost (non‐physical) reflections. These ghost reflections are the results of the cross‐correlation or auto‐correlation of primary reflections from two different depth levels, and they contain information about the seismic properties of specific layers in the subsurface. We investigated the application of ghost reflections for layer‐specific characterisation of the shallow subsurface using SI by auto‐correlation. First, we showed the technique's potential using synthetic data for a subsurface model with a lateral change in velocity, a gradient in depth for velocity, a thickness change, and a velocity change of the target layer. Then, we applied the technique to shallow subsurface field data. We also focused on improving the retrieval of ghost reflections by removing the free‐surface multiples and muting undesired events in active‐source gathers before applying SI. Our results demonstrate that the ghost reflections can be used advantageously to characterise the layer that causes them to appear in the results of SI. Consequently, they can also provide valuable information for imaging and monitoring shallow subsurface structures.This article is protected by copyright. All rights reserved","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135252793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Indresh Kumar, V. Ramesh Babu, B. V. L. Kumar, J. K. Dash, A. K. Chaturvedi
Abstract Induced polarization (IP) effect is widely used in the search of disseminated minerals all over the world. Spectral parameters computed from time‐domain IP data play a significant role in characterizing the sources, but mineral identification still remains a challenge. In this paper, the Levenberg–Marquardt method of inversion is adopted in estimating the spectral parameters from time‐domain IP data to identify the polarizable sources. The algorithm is tested on synthetic time‐domain IP data for its robustness to variable noise levels. Model sensitivity analyses on synthetic data were also studied with respect to acquisition time and each individual model parameter. Error analyses on extracted parameters indicated that these are well resolved and correlated if the relaxation time is within the range of acquisition time. The parameters remain poorly resolved/unresolved for smaller values of chargeability and frequency dependence. The algorithm has also been tested over known case histories of time‐domain IP data and compared the estimated spectral parameters with those of published results. The inferences drawn from computed spectral parameters on field‐observed IP transients are in good correlation with other data sets and borehole information. The methodology has successfully shown its usefulness in identifying large polarizable sources occurring at shallow levels from time‐domain IP data.
{"title":"Computation of spectral parameters from time‐domain induced polarization data for mineral identification","authors":"Indresh Kumar, V. Ramesh Babu, B. V. L. Kumar, J. K. Dash, A. K. Chaturvedi","doi":"10.1002/nsg.12276","DOIUrl":"https://doi.org/10.1002/nsg.12276","url":null,"abstract":"Abstract Induced polarization (IP) effect is widely used in the search of disseminated minerals all over the world. Spectral parameters computed from time‐domain IP data play a significant role in characterizing the sources, but mineral identification still remains a challenge. In this paper, the Levenberg–Marquardt method of inversion is adopted in estimating the spectral parameters from time‐domain IP data to identify the polarizable sources. The algorithm is tested on synthetic time‐domain IP data for its robustness to variable noise levels. Model sensitivity analyses on synthetic data were also studied with respect to acquisition time and each individual model parameter. Error analyses on extracted parameters indicated that these are well resolved and correlated if the relaxation time is within the range of acquisition time. The parameters remain poorly resolved/unresolved for smaller values of chargeability and frequency dependence. The algorithm has also been tested over known case histories of time‐domain IP data and compared the estimated spectral parameters with those of published results. The inferences drawn from computed spectral parameters on field‐observed IP transients are in good correlation with other data sets and borehole information. The methodology has successfully shown its usefulness in identifying large polarizable sources occurring at shallow levels from time‐domain IP data.","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sophie Marie Stephan, Niklas Allroggen, Jens Tronicke
ABSTRACT Cost‐effective computing capabilities have paved the road for the use of numerical modelling to develop advanced methods and applications of ground‐penetrating radar (GPR). Realistic synthetic data and the corresponding modelling techniques, respectively, should consider all subsurface and above‐ground aspects that influence GPR wave propagation and the characteristics of recorded signals. Critical aspects that can be realized in modern GPR modelling tools include heterogeneous and frequency‐dependent material properties, complex structures and interface geometries as well as three‐dimensional antenna models, including the interaction between the antenna and the subsurface. However, realistic noise related to the electronic components of a GPR system or ambient electromagnetic noise is often not considered, or simplified by assuming a white Gaussian noise model which is added to the modelled data. We present an approach to include realistic noise scenarios as typically observed in GPR field data into the flow of modelling synthetic GPR data. In our approach, we extract the noise from recorded GPR traces and add it to the modelled GPR data via a convolution‐based process. We illustrate our methodology using a modelling exercise, where we contaminate a synthetic two‐dimensional GPR dataset with frequency‐dependent noise recorded in an urban environment. Comparing our noise‐contaminated synthetic data with field data recorded in a similar environment illustrates that our method allows the generation of synthetic GPR with realistic noise characteristics and further highlights the limitations of assuming pure white Gaussian noise models.
{"title":"Adding realistic noise models to synthetic ground‐penetrating radar data","authors":"Sophie Marie Stephan, Niklas Allroggen, Jens Tronicke","doi":"10.1002/nsg.12273","DOIUrl":"https://doi.org/10.1002/nsg.12273","url":null,"abstract":"ABSTRACT Cost‐effective computing capabilities have paved the road for the use of numerical modelling to develop advanced methods and applications of ground‐penetrating radar (GPR). Realistic synthetic data and the corresponding modelling techniques, respectively, should consider all subsurface and above‐ground aspects that influence GPR wave propagation and the characteristics of recorded signals. Critical aspects that can be realized in modern GPR modelling tools include heterogeneous and frequency‐dependent material properties, complex structures and interface geometries as well as three‐dimensional antenna models, including the interaction between the antenna and the subsurface. However, realistic noise related to the electronic components of a GPR system or ambient electromagnetic noise is often not considered, or simplified by assuming a white Gaussian noise model which is added to the modelled data. We present an approach to include realistic noise scenarios as typically observed in GPR field data into the flow of modelling synthetic GPR data. In our approach, we extract the noise from recorded GPR traces and add it to the modelled GPR data via a convolution‐based process. We illustrate our methodology using a modelling exercise, where we contaminate a synthetic two‐dimensional GPR dataset with frequency‐dependent noise recorded in an urban environment. Comparing our noise‐contaminated synthetic data with field data recorded in a similar environment illustrates that our method allows the generation of synthetic GPR with realistic noise characteristics and further highlights the limitations of assuming pure white Gaussian noise models.","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135648621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nelson Ricardo Coelho Flores Zuniga, Deyan Draganov, Ranajit Ghose
Abstract Using post‐critical reflection data, it is possible to obtain useful information that allows more reliable geological characterization of the subsurface. However, the strong distortion caused by the phase shift in post‐critical wavelets makes the use of post‐critical reflections rather challenging. For this reason, an approach which is capable of estimating the phase shift of each wavelet of a reflection event in a data‐driven manner is desirable. In this vein, in case the frequency spectrum of a wavelet can be correctly estimated, it is possible to estimate the instantaneous phase shift. In this work, we propose an approach which can perform such estimation based on spectral recomposition of seismic data. We design an inversion approach in order to reconstruct the seismic spectrum of the wavelets of a reflection event, which subsequently allows us to estimate the instantaneous phase of each wavelet of the near‐surface reflection events without performing prior velocity analysis and/or critical‐angle estimation. After finding the instantaneous phase for each wavelet of a reflection event, we show next how one can find the respective phase shifts that can then be corrected.
{"title":"Phase‐shift correction of seismic reflections by means of spectral recomposition","authors":"Nelson Ricardo Coelho Flores Zuniga, Deyan Draganov, Ranajit Ghose","doi":"10.1002/nsg.12271","DOIUrl":"https://doi.org/10.1002/nsg.12271","url":null,"abstract":"Abstract Using post‐critical reflection data, it is possible to obtain useful information that allows more reliable geological characterization of the subsurface. However, the strong distortion caused by the phase shift in post‐critical wavelets makes the use of post‐critical reflections rather challenging. For this reason, an approach which is capable of estimating the phase shift of each wavelet of a reflection event in a data‐driven manner is desirable. In this vein, in case the frequency spectrum of a wavelet can be correctly estimated, it is possible to estimate the instantaneous phase shift. In this work, we propose an approach which can perform such estimation based on spectral recomposition of seismic data. We design an inversion approach in order to reconstruct the seismic spectrum of the wavelets of a reflection event, which subsequently allows us to estimate the instantaneous phase of each wavelet of the near‐surface reflection events without performing prior velocity analysis and/or critical‐angle estimation. After finding the instantaneous phase for each wavelet of a reflection event, we show next how one can find the respective phase shifts that can then be corrected.","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135647981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Santin Ilaria, Roncoroni Giacomo, Forte Emanuele, Gutgesell Pietro, Pipan Michele
Abstract Scattering is often detected when ground‐penetrating radar (GPR) surveys are performed on glaciers at different latitudes and in various environments. This event is often seen as an undesirable feature on data, but it can be exploited to quantify the debris content in mountain glaciers through a dedicated scattering inversion approach. At first, we considered the possible variables affecting the scattering mechanisms, namely the dielectric properties of the scatterers, their size, shape and quantity, as well as the wavelength of the electromagnetic (EM) incident field to define the initial conditions for the inversion. Each parameter was independently evaluated with forward modelling tests to quantify its effect in the scattering mechanism. After extensive tests, we found that the dimension and the amount of scatterers are the crucial parameters. We further performed modelling randomizing the scatterer distribution and dimension, critically evaluating the stability of the approach and the complexity of the models. After the tests on synthetic data, the inversion procedure was applied to field datasets, acquired on the Eastern Gran Zebrù glacier (Central Italian Alps). The results show that even a low percentage of debris can produce high scattering. The proposed methodology is quite robust and able to provide quantitative estimates of the debris content within mountain glaciers in different conditions.
{"title":"GPR modelling and inversion to quantify the debris content within ice","authors":"Santin Ilaria, Roncoroni Giacomo, Forte Emanuele, Gutgesell Pietro, Pipan Michele","doi":"10.1002/nsg.12274","DOIUrl":"https://doi.org/10.1002/nsg.12274","url":null,"abstract":"Abstract Scattering is often detected when ground‐penetrating radar (GPR) surveys are performed on glaciers at different latitudes and in various environments. This event is often seen as an undesirable feature on data, but it can be exploited to quantify the debris content in mountain glaciers through a dedicated scattering inversion approach. At first, we considered the possible variables affecting the scattering mechanisms, namely the dielectric properties of the scatterers, their size, shape and quantity, as well as the wavelength of the electromagnetic (EM) incident field to define the initial conditions for the inversion. Each parameter was independently evaluated with forward modelling tests to quantify its effect in the scattering mechanism. After extensive tests, we found that the dimension and the amount of scatterers are the crucial parameters. We further performed modelling randomizing the scatterer distribution and dimension, critically evaluating the stability of the approach and the complexity of the models. After the tests on synthetic data, the inversion procedure was applied to field datasets, acquired on the Eastern Gran Zebrù glacier (Central Italian Alps). The results show that even a low percentage of debris can produce high scattering. The proposed methodology is quite robust and able to provide quantitative estimates of the debris content within mountain glaciers in different conditions.","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135323898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Onyebueke, M. Manzi, M. Rapetsoa, T. Kgarume, M. Westgate, R. Durrheim, Michelle Pienaar, M. Sihoyiya, Mvikeli Mpofu, M. Schoor, Phumlani Kubeka
Improving the exploration of deep‐seated mineral deposits and assessing the stability of the mine pillars require that geophysical techniques are deployed in a fast and cost‐effective manner with minimal environmental impact. This research presents results from in‐mine reflection seismic experiments and a Ground Penetrating Radar (GPR) survey conducted at Maseve platinum mine, South Africa. The research aims to develop and implement methods to image Platinum Group Metal (PGM) deposits and geological structures near mine tunnels and assess the stability of pillars. The seismic experiments were conducted using a sledgehammer source (10 lb), conventional cabled geophones (14 Hz), and a landstreamer with 4.5 Hz vertical component geophones. The GPR survey was conducted using a Noggin 500 GPR system with 500 MHz centre frequency. An image of the underlying orebody and geological structures down to 100 m from the mine tunnel floor (∼ 500 m below ground surface) was produced. We correlated the coherent reflections beneath the tunnel floor with a known Upper Group (UG2) PGM orebody. The final seismic section shows that the UG2 mineralisation is dissected by near‐vertical dykes, faults and fractures. These structures, faults in particular, are interpreted to have been active post‐mineralisation, implying that they may have contributed to the current complex geometry of the deposit. Four GPR profiles were collected around a stability pillar adjacent to the seismic lines. The radargram sections were processed to improve the S/N. The results show different patterns of fracturing and stress‐ induced structures. Perhaps, these fracturing were shown to be subvertical and constituted complex micro‐structures within the pillar, which could compromise the pillar stability and integrity. The study demonstrates that in‐mine seismic and GPR surveys can be cost‐effective and valuable for mineral exploration.This article is protected by copyright. All rights reserved
{"title":"Integration of In‐mine Seismic and GPR Surveys to Gain Advanced Knowledge of Bushveld Complex Orebodies","authors":"E. Onyebueke, M. Manzi, M. Rapetsoa, T. Kgarume, M. Westgate, R. Durrheim, Michelle Pienaar, M. Sihoyiya, Mvikeli Mpofu, M. Schoor, Phumlani Kubeka","doi":"10.1002/nsg.12270","DOIUrl":"https://doi.org/10.1002/nsg.12270","url":null,"abstract":"Improving the exploration of deep‐seated mineral deposits and assessing the stability of the mine pillars require that geophysical techniques are deployed in a fast and cost‐effective manner with minimal environmental impact. This research presents results from in‐mine reflection seismic experiments and a Ground Penetrating Radar (GPR) survey conducted at Maseve platinum mine, South Africa. The research aims to develop and implement methods to image Platinum Group Metal (PGM) deposits and geological structures near mine tunnels and assess the stability of pillars. The seismic experiments were conducted using a sledgehammer source (10 lb), conventional cabled geophones (14 Hz), and a landstreamer with 4.5 Hz vertical component geophones. The GPR survey was conducted using a Noggin 500 GPR system with 500 MHz centre frequency. An image of the underlying orebody and geological structures down to 100 m from the mine tunnel floor (∼ 500 m below ground surface) was produced. We correlated the coherent reflections beneath the tunnel floor with a known Upper Group (UG2) PGM orebody. The final seismic section shows that the UG2 mineralisation is dissected by near‐vertical dykes, faults and fractures. These structures, faults in particular, are interpreted to have been active post‐mineralisation, implying that they may have contributed to the current complex geometry of the deposit. Four GPR profiles were collected around a stability pillar adjacent to the seismic lines. The radargram sections were processed to improve the S/N. The results show different patterns of fracturing and stress‐ induced structures. Perhaps, these fracturing were shown to be subvertical and constituted complex micro‐structures within the pillar, which could compromise the pillar stability and integrity. The study demonstrates that in‐mine seismic and GPR surveys can be cost‐effective and valuable for mineral exploration.This article is protected by copyright. All rights reserved","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41815583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Papadopoulou Myrto, Malehmir Alireza, Markovic Magdalena, Berglund Johan
Seismic investigations were performed at a site in the southwest of Sweden where major quick‐clay landslides have occurred in the past. Given the potential high risk of the area and the presence of medium‐sized infrastructures, the site posed a need for detailed investigations in a wide depth range and in high resolution. A high‐fold seismic survey was designed and conducted along two profiles using 1–2 m receiver and shot spacing in order to retrieve both P‐ and S‐wavefield seismic images from vertical component data. The data were analyzed combining first‐break traveltime tomography and surface‐wave analysis as well as P‐ and S‐wavefield reflection seismic imaging. Using the first breaks, P‐wave velocity (VP) models were estimated, indicating the bedrock topography along the profiles and the sediment characteristics. The S‐wave velocity (Vs) models were estimated from the surface waves and indicated areas of low shear strength. Combined with VP and Vs models, this permits the estimation of VP/VS, a parameter that can indicate areas with high water content, significant for the detection of quick clays and possible liquefaction issues. The results are integrated with the P‐ and S‐wave reflection seismic images and compared with other geophysical investigations such as magnetic and gravity data that were collected along the profiles.This article is protected by copyright. All rights reserved
{"title":"High‐resolution P‐ and S‐wavefield seismic investigations of a quick‐clay site in southwest of Sweden","authors":"Papadopoulou Myrto, Malehmir Alireza, Markovic Magdalena, Berglund Johan","doi":"10.1002/nsg.12269","DOIUrl":"https://doi.org/10.1002/nsg.12269","url":null,"abstract":"Seismic investigations were performed at a site in the southwest of Sweden where major quick‐clay landslides have occurred in the past. Given the potential high risk of the area and the presence of medium‐sized infrastructures, the site posed a need for detailed investigations in a wide depth range and in high resolution. A high‐fold seismic survey was designed and conducted along two profiles using 1–2 m receiver and shot spacing in order to retrieve both P‐ and S‐wavefield seismic images from vertical component data. The data were analyzed combining first‐break traveltime tomography and surface‐wave analysis as well as P‐ and S‐wavefield reflection seismic imaging. Using the first breaks, P‐wave velocity (VP) models were estimated, indicating the bedrock topography along the profiles and the sediment characteristics. The S‐wave velocity (Vs) models were estimated from the surface waves and indicated areas of low shear strength. Combined with VP and Vs models, this permits the estimation of VP/VS, a parameter that can indicate areas with high water content, significant for the detection of quick clays and possible liquefaction issues. The results are integrated with the P‐ and S‐wave reflection seismic images and compared with other geophysical investigations such as magnetic and gravity data that were collected along the profiles.This article is protected by copyright. All rights reserved","PeriodicalId":49771,"journal":{"name":"Near Surface Geophysics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48948154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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