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}
In underground tunnel constructions, belt conveyors or subway trains can be used as passive sources for time-lapse seismic assessments of surrounding formations. The key technology of passive seismic processes is seismic interferometry (SI), which has the ability to extract the Green's function between any two points in a medium of interest. However, since the process results are typically required to meet certain premise assumptions, the current SI methods cannot be directly used for belt conveyors. In the current study, this type of source is referred to as a near-field thread source and the proposed new SI method is adapted to this type of source. There are mainly two types of SI methods: SI by cross-correlation and SI by multi-dimensional deconvolution. The former requires that the passive source be uniformly distributed in the far field, while the latter relaxes the requirements for uniform distribution yet still requires far field sources. When the first assumptions are violated, the correlation function is proportional to a Green's function with a blurred source. The source blurring is then quantified by what is referred to as an interferometric point-spread function, which can be derived from the observed data. Therefore, using SI by MDD can effectively deblur the source of the Green's function by deconvolving the PSF. In this study, one set of geophones is located in one tunnel as the passive source, and another set is in an adjacent tunnel. However, since the setup almost coincided with the distribution of the passive sources, the spatial (wavenumber) spectrum of the PSF is too broad to be inverted. Therefore, a conventional MDD method is not suitable for this study's experiments. This study found that another PSF could be obtained from the data of the adjacent tunnel. Subsequently, a new MDD formula based on the new PSF is derived and compared with the derivation processes of the conventional MDD formula. Then, the feasibility of the proposed method is verified using numerical simulations.
{"title":"Multi-Dimensional Deconvolution for Near-Field Thread Seismic Sources in Tunnels","authors":"Lu Bin","doi":"10.32389/jeeg20-057","DOIUrl":"https://doi.org/10.32389/jeeg20-057","url":null,"abstract":"In underground tunnel constructions, belt conveyors or subway trains can be used as passive sources for time-lapse seismic assessments of surrounding formations. The key technology of passive seismic processes is seismic interferometry (SI), which has the ability to extract the Green's function between any two points in a medium of interest. However, since the process results are typically required to meet certain premise assumptions, the current SI methods cannot be directly used for belt conveyors. In the current study, this type of source is referred to as a near-field thread source and the proposed new SI method is adapted to this type of source. There are mainly two types of SI methods: SI by cross-correlation and SI by multi-dimensional deconvolution. The former requires that the passive source be uniformly distributed in the far field, while the latter relaxes the requirements for uniform distribution yet still requires far field sources. When the first assumptions are violated, the correlation function is proportional to a Green's function with a blurred source. The source blurring is then quantified by what is referred to as an interferometric point-spread function, which can be derived from the observed data. Therefore, using SI by MDD can effectively deblur the source of the Green's function by deconvolving the PSF. In this study, one set of geophones is located in one tunnel as the passive source, and another set is in an adjacent tunnel. However, since the setup almost coincided with the distribution of the passive sources, the spatial (wavenumber) spectrum of the PSF is too broad to be inverted. Therefore, a conventional MDD method is not suitable for this study's experiments. This study found that another PSF could be obtained from the data of the adjacent tunnel. Subsequently, a new MDD formula based on the new PSF is derived and compared with the derivation processes of the conventional MDD formula. Then, the feasibility of the proposed method is verified using numerical simulations.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"14 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75215533","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}
R. Adams, B. Miller, W. Kress, S. Ikard, Jason D. Payne, Walter H. Killion
Within the State of Arkansas, there is an increasing number of aging dams and levees that have little to no documentation concerning their construction or composition. Surface geophysical surveys offer a non-intrusive method for investigating these structures to describe their lithologic makeup, evaluate the materials constructed upon, and identify potential flow paths through them. Techniques such as electrical resistivity tomography, seismic refraction, and electromagnetic induction have been used to image dams and levees. They require additional information from geologic outcrops, geotechnical borings, or drill cores to make informed geologic interpretations of the geophysical models. These geologic models then allow the owners of these structures to make more informed decisions about their operation and maintenance. Between 2011 and 2018, the U.S. Geological Survey conducted geophysical and geotechnical investigations of three earthen structures in Arkansas. Electrical and electromagnetic geophysical data were used to develop lithologic models of these structures and characterize the underlying geology. Self-potential surveys were utilized to detect the movement of water through these structures and identify any possible seepage pathways. Geotechnical methods such as electric and hydraulic direct-push well logs and cores acted as a control on the geophysical interpretations and a confirmation of anomalies. This integrated approach detected the lack of an impermeable core within a levee, imaged a change in lithology of the bedrock forming the seal beneath a gravity dam, and identified a potential seepage feature within the core of an earthen dam. These results further support that this method of extending known lithologic features via surface and borehole geophysics is a useful approach for characterizing earthen water-control structures.
{"title":"Evaluation of Electrical and Electromagnetic Geophysical Techniques to Inspect Earthen Dam and Levee Structures in Arkansas","authors":"R. Adams, B. Miller, W. Kress, S. Ikard, Jason D. Payne, Walter H. Killion","doi":"10.32389/jeeg20-063","DOIUrl":"https://doi.org/10.32389/jeeg20-063","url":null,"abstract":"Within the State of Arkansas, there is an increasing number of aging dams and levees that have little to no documentation concerning their construction or composition. Surface geophysical surveys offer a non-intrusive method for investigating these structures to describe their lithologic makeup, evaluate the materials constructed upon, and identify potential flow paths through them. Techniques such as electrical resistivity tomography, seismic refraction, and electromagnetic induction have been used to image dams and levees. They require additional information from geologic outcrops, geotechnical borings, or drill cores to make informed geologic interpretations of the geophysical models. These geologic models then allow the owners of these structures to make more informed decisions about their operation and maintenance. Between 2011 and 2018, the U.S. Geological Survey conducted geophysical and geotechnical investigations of three earthen structures in Arkansas. Electrical and electromagnetic geophysical data were used to develop lithologic models of these structures and characterize the underlying geology. Self-potential surveys were utilized to detect the movement of water through these structures and identify any possible seepage pathways. Geotechnical methods such as electric and hydraulic direct-push well logs and cores acted as a control on the geophysical interpretations and a confirmation of anomalies. This integrated approach detected the lack of an impermeable core within a levee, imaged a change in lithology of the bedrock forming the seal beneath a gravity dam, and identified a potential seepage feature within the core of an earthen dam. These results further support that this method of extending known lithologic features via surface and borehole geophysics is a useful approach for characterizing earthen water-control structures.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"46 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79750072","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}
Pub Date : 2021-12-01DOI: 10.32389/1083-1363-26.4.323
{"title":"Best Reviewers and Authors' Biographies","authors":"","doi":"10.32389/1083-1363-26.4.323","DOIUrl":"https://doi.org/10.32389/1083-1363-26.4.323","url":null,"abstract":"","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"19 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82857987","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}
André C.G. Kowalski, C. Mendonça, U. Ofterdinger, H. Rocha
Groundwater transport in crystalline rocks follows pathways along fractured zones because of low primary porosity and permeability in such formations. Fractured systems encompass an imbricated set of joints and fractures with different lengths, apertures and orientations resulting in complex permeable systems with heterogeneous groundwater transport properties. Geophysical well logging has proved effectiveness in detecting depth levels with denser fracture distributions as well as the apparent aperture of fractures contributing to groundwater flow. In many cases, the extension spanned by a fracture network cannot be directly inferred because it may extend beyond the radius of investigation of common well logging probes, thus preventing quantitative estimation of critical length for lateral extension a connected fractured system may have. Here we apply a percolation theory model to estimate the critical length as inferred from the linear density of fracture distribution observed at the borehole wall with an optical imaging probe. Our results are analyzed with electrical well logging data (normal resistivity and single-point resistance) cross borehole slug tests using a set of three boreholes. A critical length of 3.9 m was inferred with a percolation model which revealed consistency with the cross borehole slug tests from two wells situated 10 m and 30 m in the vicinity of the monitored borehole. Our results suggest the utility of inferring critical percolation lengths from fracture parameters obtained using standard well logging imaging techniques with potential applications to evaluate groundwater resources, characterize contaminated sites and provide geotechnical information for works in fractured formations.
{"title":"Fracture Critical Length Estimative Using Percolation Theory and Well Logging Data","authors":"André C.G. Kowalski, C. Mendonça, U. Ofterdinger, H. Rocha","doi":"10.32389/jeeg21-019","DOIUrl":"https://doi.org/10.32389/jeeg21-019","url":null,"abstract":"Groundwater transport in crystalline rocks follows pathways along fractured zones because of low primary porosity and permeability in such formations. Fractured systems encompass an imbricated set of joints and fractures with different lengths, apertures and orientations resulting in complex permeable systems with heterogeneous groundwater transport properties. Geophysical well logging has proved effectiveness in detecting depth levels with denser fracture distributions as well as the apparent aperture of fractures contributing to groundwater flow. In many cases, the extension spanned by a fracture network cannot be directly inferred because it may extend beyond the radius of investigation of common well logging probes, thus preventing quantitative estimation of critical length for lateral extension a connected fractured system may have. Here we apply a percolation theory model to estimate the critical length as inferred from the linear density of fracture distribution observed at the borehole wall with an optical imaging probe. Our results are analyzed with electrical well logging data (normal resistivity and single-point resistance) cross borehole slug tests using a set of three boreholes. A critical length of 3.9 m was inferred with a percolation model which revealed consistency with the cross borehole slug tests from two wells situated 10 m and 30 m in the vicinity of the monitored borehole. Our results suggest the utility of inferring critical percolation lengths from fracture parameters obtained using standard well logging imaging techniques with potential applications to evaluate groundwater resources, characterize contaminated sites and provide geotechnical information for works in fractured formations.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"75 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87007720","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}
Surface wave methods have increased in popularity as a means to acquire rapid and accurate shear wave velocity ( VS) profiles for engineering applications. Use of the multichannel analysis of surface waves (MASW) method, in particular, has proliferated due to multiple factors, including the ease with which strong signal-to-noise ratio can be achieved and the increased dispersion resolution offered by multichannel acquisitions. However, typical MASW processing to extract dispersion information assumes the surface waves propagate through a layered model. Errors can arise when significant lateral variability is present in the underlying stratigraphy as encountered in certain geologic settings such as residual deposits. This study investigated the effects of such variability on the dispersion information acquired with MASW. In particular, a spatially-correlated Gaussian random field was used to model the natural fluctuations in stiffness introduced by depositional processes, which differs from the approach in other studies where more specific anomalous features have been explored. Numerical modeling was subsequently performed to simulate surface wave propagation in the representative geotechnical site condition. The recovered surface waves were used to develop a subsurface stiffness profile using a dispersion-based pseudo-2D MASW approach and a tomographic approach using full waveform inversion (FWI). The results demonstrate that considerable natural spatial variability significantly complicates interpretation of dispersion information in two primary ways: (1) uncertainty can arise regarding what the dispersion curve exactly quantifies since none of the underlying VS profiles nor the average VS profile are obtained; and (2) the dispersion images exhibit evidence of false depth-related dispersion information indicative of multiple “fundamental” modes from the superposition of multiple stratigraphic units. The FWI procedure that bypasses extraction of dispersion information was found to better recover the underlying subsurface conditions when compared to the pseudo-2D MASW results at the cost of additional computational efforts.
{"title":"Full Waveform Tomography to Address Challenges with Surface Wave Dispersion Information Caused by Significant Stochastic Variability of Subsurface Stiffness","authors":"J. Coe, Siavash Mahvelati","doi":"10.32389/jeeg21-013","DOIUrl":"https://doi.org/10.32389/jeeg21-013","url":null,"abstract":"Surface wave methods have increased in popularity as a means to acquire rapid and accurate shear wave velocity ( VS) profiles for engineering applications. Use of the multichannel analysis of surface waves (MASW) method, in particular, has proliferated due to multiple factors, including the ease with which strong signal-to-noise ratio can be achieved and the increased dispersion resolution offered by multichannel acquisitions. However, typical MASW processing to extract dispersion information assumes the surface waves propagate through a layered model. Errors can arise when significant lateral variability is present in the underlying stratigraphy as encountered in certain geologic settings such as residual deposits. This study investigated the effects of such variability on the dispersion information acquired with MASW. In particular, a spatially-correlated Gaussian random field was used to model the natural fluctuations in stiffness introduced by depositional processes, which differs from the approach in other studies where more specific anomalous features have been explored. Numerical modeling was subsequently performed to simulate surface wave propagation in the representative geotechnical site condition. The recovered surface waves were used to develop a subsurface stiffness profile using a dispersion-based pseudo-2D MASW approach and a tomographic approach using full waveform inversion (FWI). The results demonstrate that considerable natural spatial variability significantly complicates interpretation of dispersion information in two primary ways: (1) uncertainty can arise regarding what the dispersion curve exactly quantifies since none of the underlying VS profiles nor the average VS profile are obtained; and (2) the dispersion images exhibit evidence of false depth-related dispersion information indicative of multiple “fundamental” modes from the superposition of multiple stratigraphic units. The FWI procedure that bypasses extraction of dispersion information was found to better recover the underlying subsurface conditions when compared to the pseudo-2D MASW results at the cost of additional computational efforts.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"20 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90459524","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}
Raytracing is a fast and effective numerical simulation method of the seismic wavefield. It plays an important role in field data acquisition design, wavefield analysis, identification, and tomography. In raytracing, pseudo-bending (PB) is a fast and efficient method, but it is unsuitable for complex media with sudden velocity changes. An improved pseudo-bending raytracing method is presented in this paper, which can be applied to any complex medium. The proposed method first decomposes complex medium into multi-scale velocity components and then applies the pseudo-bending approach to the velocity components of different scales. The numerical simulation of seismic wavefield from models shows that the improved multi-scale pseudo-bending (MSPB) method can be applied to a medium with continuous velocity variation and any complex medium with abrupt velocity change.
{"title":"Multi-Scale Pseudo-Bending Raytracing for Arbitrary Complex Media","authors":"Zhang Huan-lan, Wang Bao-Li","doi":"10.32389/jeeg19-007","DOIUrl":"https://doi.org/10.32389/jeeg19-007","url":null,"abstract":"Raytracing is a fast and effective numerical simulation method of the seismic wavefield. It plays an important role in field data acquisition design, wavefield analysis, identification, and tomography. In raytracing, pseudo-bending (PB) is a fast and efficient method, but it is unsuitable for complex media with sudden velocity changes. An improved pseudo-bending raytracing method is presented in this paper, which can be applied to any complex medium. The proposed method first decomposes complex medium into multi-scale velocity components and then applies the pseudo-bending approach to the velocity components of different scales. The numerical simulation of seismic wavefield from models shows that the improved multi-scale pseudo-bending (MSPB) method can be applied to a medium with continuous velocity variation and any complex medium with abrupt velocity change.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"71 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85879602","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}
Zhengyu Liu, Yongheng Zhang, Xinxin Zhang, Huaihong Wang, L. Nie, Xinji Xu, Ning Wang, Ningbo Li
In recent decades, the DC resistivity method has been applied to geophysical monitoring because of its sensitivity to hydrogeological properties. However, existing inversion algorithms cannot give a reasonable image if fluid migration is sudden and unpredictable. Additionally, systematic or measurement errors can severely interfere with accurate object location. To address these issues, we propose an improved time series inversion method for cross-hole electrical resistivity tomography (cross-hole ERT) based on the Extended Kalman Filter (EKF). Traditional EKF includes two steps to obtain the current model state: prediction and correction. We improved the prediction step by introducing the grey time series prediction method to create a new regular model sequence that can infer the potential trend of underground resistivity changes and provide a prior estimation state for reference during the next moment. To include more current information in the prior estimation state and decrease the non-uniqueness, the prediction model needs to be further updated by the least-squares method. For the correction step, we used single time-step multiple filtering to better deal with the case of sudden and rapid changes. We designed three different numerical tests simulating rapid changes in a fluid to validate the proposed method. The proposed method can capture rapid changes in the groundwater transport rate and direction of the groundwater movement for real-time imaging. Model and field experiments were performed. The inversion results of the model experiment were generally consistent with the results of dye tracing, and the groundwater behavior in the field experiment was consistent with the predicted groundwater evolution process.
{"title":"Time Series Data Inversion and Monitoring Method for Cross-Hole ERT Based on an Improved Extended Kalman Filter","authors":"Zhengyu Liu, Yongheng Zhang, Xinxin Zhang, Huaihong Wang, L. Nie, Xinji Xu, Ning Wang, Ningbo Li","doi":"10.32389/jeeg20-051","DOIUrl":"https://doi.org/10.32389/jeeg20-051","url":null,"abstract":"In recent decades, the DC resistivity method has been applied to geophysical monitoring because of its sensitivity to hydrogeological properties. However, existing inversion algorithms cannot give a reasonable image if fluid migration is sudden and unpredictable. Additionally, systematic or measurement errors can severely interfere with accurate object location. To address these issues, we propose an improved time series inversion method for cross-hole electrical resistivity tomography (cross-hole ERT) based on the Extended Kalman Filter (EKF). Traditional EKF includes two steps to obtain the current model state: prediction and correction. We improved the prediction step by introducing the grey time series prediction method to create a new regular model sequence that can infer the potential trend of underground resistivity changes and provide a prior estimation state for reference during the next moment. To include more current information in the prior estimation state and decrease the non-uniqueness, the prediction model needs to be further updated by the least-squares method. For the correction step, we used single time-step multiple filtering to better deal with the case of sudden and rapid changes. We designed three different numerical tests simulating rapid changes in a fluid to validate the proposed method. The proposed method can capture rapid changes in the groundwater transport rate and direction of the groundwater movement for real-time imaging. Model and field experiments were performed. The inversion results of the model experiment were generally consistent with the results of dye tracing, and the groundwater behavior in the field experiment was consistent with the predicted groundwater evolution process.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"73 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81012474","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}
N. Yurkevich, S. Bortnikova, V. Olenchenko, Tanya Fedorova, Y. Karin, A. Edelev, P. Osipova, O. Saeva
Mine tailings are a very active system in which the processes of oxidation, dissolution, and the re-deposition of substances occur in real-time. Time-lapse electrical resistivity tomography and soil-gas measurements have been used on abandoned mine tailings under a highly continental climate, Western Siberia, Russia. The electrical resistivity tomography method allows the structure of the tailings to be determined, namely, its electrophysical parameters, which are related to the chemical composition and geochemical characteristics of the subsurface substance. The aim of this work is to determine the variations in the geoelectrical zoning of sulfide-bearing mine tailings depending on fluctuations in environmental conditions, i.e., ground and air temperature, in conjunction with volatile compounds of environmental concern emanating from the tailings (SO2, CS2, C2H6S). The hourly observations revealed that the configuration of the geoelectrical section varies during the day. The concentration of gases in the surface air layer varied in accordance with the ambient temperature conditions. In general, the minimum gas concentrations were determined at night, and the increase in gas concentrations began when the temperature increased. The dependence of gas formation on temperature conditions differed during the daytime and nighttime. In warmer hours, gas concentrations are highest. At night, when there was a decrease in the temperature of air and then in the ground temperature, a local increase in the concentration of all measured gases occurred at the maximum temperature difference in the air (14.1 °C), and the ground remained relatively warm (20.8 °C). There is a close relationship between ground temperature, electrical resistivity, and the rate of gas production. Local anomalies with the greatest variation in electrical resistivity are associated with the zones that have the most active gas emanations.
{"title":"Time-Lapse Electrical Resistivity Tomography and Soil-Gas Measurements on Abandoned Mine Tailings Under a Highly Continental Climate, Western Siberia, Russia","authors":"N. Yurkevich, S. Bortnikova, V. Olenchenko, Tanya Fedorova, Y. Karin, A. Edelev, P. Osipova, O. Saeva","doi":"10.32389/jeeg21-004","DOIUrl":"https://doi.org/10.32389/jeeg21-004","url":null,"abstract":"Mine tailings are a very active system in which the processes of oxidation, dissolution, and the re-deposition of substances occur in real-time. Time-lapse electrical resistivity tomography and soil-gas measurements have been used on abandoned mine tailings under a highly continental climate, Western Siberia, Russia. The electrical resistivity tomography method allows the structure of the tailings to be determined, namely, its electrophysical parameters, which are related to the chemical composition and geochemical characteristics of the subsurface substance. The aim of this work is to determine the variations in the geoelectrical zoning of sulfide-bearing mine tailings depending on fluctuations in environmental conditions, i.e., ground and air temperature, in conjunction with volatile compounds of environmental concern emanating from the tailings (SO2, CS2, C2H6S). The hourly observations revealed that the configuration of the geoelectrical section varies during the day. The concentration of gases in the surface air layer varied in accordance with the ambient temperature conditions. In general, the minimum gas concentrations were determined at night, and the increase in gas concentrations began when the temperature increased. The dependence of gas formation on temperature conditions differed during the daytime and nighttime. In warmer hours, gas concentrations are highest. At night, when there was a decrease in the temperature of air and then in the ground temperature, a local increase in the concentration of all measured gases occurred at the maximum temperature difference in the air (14.1 °C), and the ground remained relatively warm (20.8 °C). There is a close relationship between ground temperature, electrical resistivity, and the rate of gas production. Local anomalies with the greatest variation in electrical resistivity are associated with the zones that have the most active gas emanations.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"45 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74188248","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}
Groundwater is a nearly exclusive water resource, specifically for the communities which are part of the Chicago metropolitan area. However, water shortage is predicted for many communities in this region, and demand for locating and delineating groundwater is increasing to fulfill the water supply. Shallow sand and gravel aquifers within the glacial deposits of the area specifically are high volume aquifer and less stressed compare to deeper bedrock aquifer. Yet, these aquifers are poorly understood in terms of their extent and lateral variability. This study applied the shear-wave seismic reflection method to delineate the thickness, lateral extent, and internal variability of these aquifers. We acquired horizontally polarized shear-wave (SH-waves) reflection data along five profiles of a total length of 11 km using the land streamer technology in McHenry County in northern Illinois to delineate sand and gravel aquifers. As shear waves propagate through the rock matrix and less sensitive to the presence of water, information from nearby borings and water wells aided the interpretation of the acquired SH-wave seismic profiles. We delineated multiple sand and gravel units of potential aquifers of different thicknesses and lateral extent along with the seismic profiles. The relatively higher vertical and lateral resolution of the shear-waves reflection method and its insensitivity to water saturation or chemistry made it an ideal method to resolve sand and gravel units of potential aquifers within the complex geological environment if aided by water-well information.
{"title":"Seismic Shear-Wave Characterization of Sand and Gravel Groundwater Aquifers in Northern Illinois","authors":"Zonaed Sazal, A. Ismail, J. Thomason","doi":"10.32389/jeeg21-015","DOIUrl":"https://doi.org/10.32389/jeeg21-015","url":null,"abstract":"Groundwater is a nearly exclusive water resource, specifically for the communities which are part of the Chicago metropolitan area. However, water shortage is predicted for many communities in this region, and demand for locating and delineating groundwater is increasing to fulfill the water supply. Shallow sand and gravel aquifers within the glacial deposits of the area specifically are high volume aquifer and less stressed compare to deeper bedrock aquifer. Yet, these aquifers are poorly understood in terms of their extent and lateral variability. This study applied the shear-wave seismic reflection method to delineate the thickness, lateral extent, and internal variability of these aquifers. We acquired horizontally polarized shear-wave (SH-waves) reflection data along five profiles of a total length of 11 km using the land streamer technology in McHenry County in northern Illinois to delineate sand and gravel aquifers. As shear waves propagate through the rock matrix and less sensitive to the presence of water, information from nearby borings and water wells aided the interpretation of the acquired SH-wave seismic profiles. We delineated multiple sand and gravel units of potential aquifers of different thicknesses and lateral extent along with the seismic profiles. The relatively higher vertical and lateral resolution of the shear-waves reflection method and its insensitivity to water saturation or chemistry made it an ideal method to resolve sand and gravel units of potential aquifers within the complex geological environment if aided by water-well information.","PeriodicalId":15748,"journal":{"name":"Journal of Environmental and Engineering Geophysics","volume":"20 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79860245","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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