From surface to intracellular non-invasive nanoscale study of living cells impairments

NASA Astrophysics Data System (ADS)

Ewald, M.; Tetard, L.; Elie-Caille, C.; Nicod, L.; Passian, A.; Bourillot, E.; Lesniewska, E.

2014-07-01

Among the enduring challenges in nanoscience, subsurface characterization of living cells holds major stakes. Developments in nanometrology for soft matter thriving on the sensitivity and high resolution benefits of atomic force microscopy have enabled detection of subsurface structures at the nanoscale. However, measurements in liquid environments remain complex, in particular in the subsurface domain. Here we introduce liquid-mode synthesizing atomic force microscopy (l-MSAFM) to study both the inner structures and the chemically induced intracellular impairments of living cells. Specifically, we visualize the intracellular stress effects of glyphosate on living keratinocytes skin cells. This new approach, l-MSAFM, for nanoscale imaging of living cell in their physiological environment or in presence of a chemical stress agent could resolve the loss of inner structures induced by glyphosate, the main component of a well-known pesticide (RoundUp™). This firsthand ability to monitor the cell’s inner response to external stimuli non-destructively and in liquid, has the potential to unveil critical nanoscale mechanisms of life science.

Identifying future directions for subsurface hydrocarbon migration research

NASA Astrophysics Data System (ADS)

Leifer, I.; Clark, J. F.; Luyendyk, B.; Valentine, D.

Subsurface hydrocarbon migration is important for understanding the input and impacts of natural hydrocarbon seepage on the environment. Great uncertainties remain in most aspects of hydrocarbon migration, including some basic mechanisms of this four-phase flow of tar, oil, water, and gas through the complex fracture-network geometry particularly since the phases span a wide range of properties. Academic, government, and industry representatives recently attended a workshop to identify the areas of greatest need for future research in shallow hydrocarbon migration.Novel approaches such as studying temporal and spatial seepage variations and analogous geofluid systems (e.g., geysers and trickle beds) allow deductions of subsurface processes and structures that remain largely unclear. Unique complexities exist in hydrocarbon migration due to its multiphase flow and complex geometry, including in-situ biological weathering. Furthermore, many aspects of the role of hydrocarbons (positive and negative) in the environment are poorly understood, including how they enter the food chain (respiration, consumption, etc.) and “percolate” to higher trophic levels. But understanding these ecological impacts requires knowledge of the emissions' temporal and spatial variability and trajectories.

3D resistivity survey for shallow subsurface fault investigations

NASA Astrophysics Data System (ADS)

Petrit, Kraipat; Klamthim, Poonnapa; Duerrast, Helmut

2018-03-01

The shallow subsurface is subject to various human activities, and the place of occurrence of geohazards, e.g. shallow active faults. The identification of the location and orientation of such faults can be vital for infrastructure development. The aim of this study was to develop a low-cost 3D resistivity survey system, with reasonable survey time for shallow fault investigations. The study area in Songkhla Province, Thailand is located in an old quarry where faults could be identified in outcrops. The study area was designed to cover the expected fault with 100 electrodes arranged in a 10×10 square grid with an electrode spacing of 3 meters in x and y axis. Each electrode in turn was used as a current and potential electrode using a dipole-dipole array. Field data have been processed and interpreted using 3DResINV. Results, presented in horizontal depth slices and vertical xz- and yz-cross sections, revealed through differences in resistivity down to 8 m depths a complex structural setting with two shallow faults and dipping sedimentary rock layers. In conclusion, this study has shown that a 3D resistivity survey can imagine complex tectonic structures, thus providing a far more insight into the shallow subsurface.

The importance of topographic corrections on magnetotelluric response data from rugged regions of Anatolia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerer, A.; Ilkisik, O.M.

1997-01-01

Topographic irregularities cause some distortions of magnetotelluric (MT) fields. In the vicinity of a topographic feature, the TM-mode distortion increases with the height and inclination of the slope. It is well-known that TM-mode topographic effects are much greater than TE-mode distortions. The authors have made a study of MT anomalies in TM-mode due to two-dimensional topography. In order to reduce these effects, the distortion tensor stripping technique was used. After corrections, the resulting data can be interpreted as if they were obtained over a flat surface and depend only on the subsurface structure. However, this technique sometimes causes some geometricalmore » distortions of the real subsurface structure. One of the aims is to overcome this failure. The authors have modified the correction coefficients by considering the actual one-dimensional geology. Model studies showed that this approach is especially useful in removing the terrain effects on complex 2D subsurface structures. The other purpose of this study is to emphasize the importance of a proper terrain correction for data from sites having mountainous topography over complex geology, e.g., strike-slip faults, suture zones and rift valleys. Some examples of MT data sets collected from the North Anatolian Fault Zone and from the thrust regions of the Western Taurides will be presented.« less

Pragmatic geometric model evaluation

NASA Astrophysics Data System (ADS)

Pamer, Robert

2015-04-01

Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to calculate basically two model variations that can be seen as geometric extremes of all available input data. This does not lead to a probability distribution for the spatial position of geometric elements but it defines zones of major (or minor resp.) geometric variations due to data uncertainty. Both model evaluations are then analyzed together to give ranges of possible model outcomes in metric units.

A novel anisotropic inversion approach for magnetotelluric data from subsurfaces with orthogonal geoelectric strike directions

NASA Astrophysics Data System (ADS)

Schmoldt, Jan-Philipp; Jones, Alan G.

2013-12-01

The key result of this study is the development of a novel inversion approach for cases of orthogonal, or close to orthogonal, geoelectric strike directions at different depth ranges, for example, crustal and mantle depths. Oblique geoelectric strike directions are a well-known issue in commonly employed isotropic 2-D inversion of MT data. Whereas recovery of upper (crustal) structures can, in most cases, be achieved in a straightforward manner, deriving lower (mantle) structures is more challenging with isotropic 2-D inversion in the case of an overlying region (crust) with different geoelectric strike direction. Thus, investigators may resort to computationally expensive and more limited 3-D inversion in order to derive the electric resistivity distribution at mantle depths. In the novel approaches presented in this paper, electric anisotropy is used to image 2-D structures in one depth range, whereas the other region is modelled with an isotropic 1-D or 2-D approach, as a result significantly reducing computational costs of the inversion in comparison with 3-D inversion. The 1- and 2-D versions of the novel approach were tested using a synthetic 3-D subsurface model with orthogonal strike directions at crust and mantle depths and their performance was compared to results of isotropic 2-D inversion. Structures at crustal depths were reasonably well recovered by all inversion approaches, whereas recovery of mantle structures varied significantly between the different approaches. Isotropic 2-D inversion models, despite decomposition of the electric impedance tensor and using a wide range of inversion parameters, exhibited severe artefacts thereby confirming the requirement of either an enhanced or a higher dimensionality inversion approach. With the anisotropic 1-D inversion approach, mantle structures of the synthetic model were recovered reasonably well with anisotropy values parallel to the mantle strike direction (in this study anisotropy was assigned to the mantle region), indicating applicability of the novel approach for basic subsurface cases. For the more complex subsurface cases, however, the anisotropic 1-D inversion approach is likely to yield implausible models of the electric resistivity distribution due to inapplicability of the 1-D approximation. Owing to the higher number of degrees of freedom, the anisotropic 2-D inversion approach can cope with more complex subsurface cases and is the recommended tool for real data sets recorded in regions with orthogonal geoelectric strike directions.

Characterising the Architecture of New Zealand's Geothermal Structural Fluid Flow Networks Using Borehole Images

NASA Astrophysics Data System (ADS)

McNamara, David; Milicich, Sarah; Massiot, Cécile

2017-04-01

Borehole imaging has been used worldwide since the 1950's to capture vital geological information on the lithology, structure, and stress conditions of the Earth's subsurface. In New Zealand both acoustic and resistivity based borehole image logs are utilised to explore the geological nature of the basement and volcanic rocks that contain the country's unique geothermal reservoirs. Borehole image logs in wells from three geothermal fields in the Taupo Volcanic Zone (TVZ) provide the first, direct, subsurface, structural orientation measurements in New Zealand geothermal reservoir lithologies. While showing an overall structural pattern aligned to the regional tectonic trend, heterogeneities are observed that provide insight into the complexity of the structurally controlled, geothermal, fluid flow pathways. Analysis of imaged stress induced features informs us that the stress field orientation in the TVZ is also not homogenous, but is variable at a local scale.

LIPID ANALYSIS TO DETERMINE THE EFFECT OF A SOURCE REMEDIAL TECHNOLOGY IN MICROBIAL ECOLOGY

EPA Science Inventory

Microbial community structures and related changes in the subsurface environment were investigated following in situ chemical oxidation (ISCO) treatment at Launch Complex 34, Cape Canaveral Air Station, Florida. The site has dense non-aqueous phase (DNAPL) concentrations of TCE ...

Idaho National Laboratory Test Area North: Application of Endpoints to Guide Adaptive Remediation at a Complex Site: INL Test Area North: Application of Endpoints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, M. Hope; Truex, Mike; Freshley, Mark

Complex sites are defined as those with difficult subsurface access, deep and/or thick zones of contamination, large areal extent, subsurface heterogeneities that limit the effectiveness of remediation, or where long-term remedies are needed to address contamination (e.g., because of long-term sources or large extent). The Test Area North at the Idaho National Laboratory, developed for nuclear fuel operations and heavy metal manufacturing, is used as a case study. Liquid wastes and sludge from experimental facilities were disposed in an injection well, which contaminated the subsurface aquifer located deep within fractured basalt. The wastes included organic, inorganic, and low-level radioactive constituents,more » with the focus of this case study on trichloroethylene. The site is used as an example of a systems-based framework that provides a structured approach to regulatory processes established for remediation under existing regulations. The framework is intended to facilitate remedy decisions and implementation at complex sites where restoration may be uncertain, require long timeframes, or involve use of adaptive management approaches. The framework facilitates site, regulator, and stakeholder interactions during the remedial planning and implementation process by using a conceptual model description as a technical foundation for decisions, identifying endpoints, which are interim remediation targets or intermediate decision points on the path to an ultimate end, and maintaining protectiveness during the remediation process. At the Test Area North, using a structured approach to implementing concepts in the endpoint framework, a three-component remedy is largely functioning as intended and is projected to meet remedial action objectives by 2095 as required. The remedy approach is being adjusted as new data become available. The framework provides a structured process for evaluating and adjusting the remediation approach, allowing site owners, regulators, and stakeholders to manage contamination at complex sites where adaptive remedies are needed.« less

Controlling Subsurface Fractures and Fluid Flow: A Basic Research Agenda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pyrak-Nolte, Laura J; DePaolo, Donald J.; Pietraß, Tanja

2015-05-22

From beneath the surface of the earth, we currently obtain about 80-percent of the energy our nation consumes each year. In the future we have the potential to generate billions of watts of electrical power from clean, green, geothermal energy sources. Our planet’s subsurface can also serve as a reservoir for storing energy produced from intermittent sources such as wind and solar, and it could provide safe, long-term storage of excess carbon dioxide, energy waste products and other hazardous materials. However, it is impossible to underestimate the complexities of the subsurface world. These complexities challenge our ability to acquire themore » scientific knowledge needed for the efficient and safe exploitation of its resources. To more effectively harness subsurface resources while mitigating the impacts of developing and using these resources, the U.S. Department of Energy established SubTER – the Subsurface Technology and Engineering RD&D Crosscut team. This DOE multi-office team engaged scientists and engineers from the national laboratories to assess and make recommendations for improving energy-related subsurface engineering. The SubTER team produced a plan with the overall objective of “adaptive control of subsurface fractures and fluid flow.”This plan revolved around four core technological pillars—Intelligent Wellbore Systems that sustain the integrity of the wellbore environment; Subsurface Stress and Induced Seismicity programs that guide and optimize sustainable energy strategies while reducing the risks associated with subsurface injections; Permeability Manipulation studies that improve methods of enhancing, impeding and eliminating fluid flow; and New Subsurface Signals that transform our ability to see into and characterize subsurface systems. The SubTER team developed an extensive R&D plan for advancing technologies within these four core pillars and also identified several areas where new technologies would require additional basic research. In response, the Office of Science, through its Office of Basic Energy Science (BES), convened a roundtable consisting of 15 national lab, university and industry geoscience experts to brainstorm basic research areas that underpin the SubTER goals but are currently underrepresented in the BES research portfolio. Held in Germantown, Maryland on May 22, 2015, the round-table participants developed a basic research agenda that is detailed in this report. Highlights include the following: -A grand challenge calling for advanced imaging of stress and geological processes to help understand how stresses and chemical substances are distributed in the subsurface—knowledge that is critical to all aspects of subsurface engineering; -A priority research direction aimed at achieving control of fluid flow through fractured media; -A priority research direction aimed at better understanding how mechanical and geochemical perturbations to subsurface rock systems are coupled through fluid and mineral interactions; -A priority research direction aimed at studying the structure, permeability, reactivity and other properties of nanoporous rocks, like shale, which have become critical energy materials and exhibit important hallmarks of mesoscale materials; -A cross-cutting theme that would accelerate development of advanced computational methods to describe heterogeneous time-dependent geologic systems that could, among other potential benefits, provide new and vastly improved models of hydraulic fracturing and its environmental impacts; -A cross-cutting theme that would lead to the creation of “geo-architected materials” with controlled repeatable heterogeneity and structure that can be tested under a variety of thermal, hydraulic, chemical and mechanical conditions relevant to subsurface systems; -A cross-cutting theme calling for new laboratory studies on both natural and geo-architected subsurface materials that deploy advanced high-resolution 3D imaging and chemical analysis methods to determine the ;rates and mechanisms of fluid-rock processes, and to test predictive models of such phenomena. Many of the key energy challenges of the future demand a greater understanding of the subsurface world in all of its complexity. This greater under- standing will improve the ability to control and manipulate the subsurface world in ways that will benefit both the economy and the environment. This report provides specific basic research pathways to address some of the most fundamental issues of energy-related subsurface engineering.« less

Marine magnetic survey and onshore gravity and magnetic survey, San Pablo Bay, northern California

USGS Publications Warehouse

Ponce, David A.; Denton, Kevin M.; Watt, Janet T.

2016-09-12

IntroductionFrom November 2011 to August 2015, the U.S. Geological Survey (USGS) collected more than 1,000 line-kilometers (length of lines surveyed in kilometers) of marine magnetic data on San Pablo Bay, 98 onshore gravity stations, and over 27 line-kilometers of ground magnetic data in northern California. Combined magnetic and gravity investigations were undertaken to study subsurface geologic structures as an aid in understanding the geologic framework and earthquake hazard potential in the San Francisco Bay Area. Furthermore, marine magnetic data illuminate local subsurface geologic features in the shallow crust beneath San Pablo Bay where geologic exposure is absent.Magnetic and gravity methods, which reflect contrasting physical properties of the subsurface, are ideal for studying San Pablo Bay. Exposed rock units surrounding San Pablo Bay consist mainly of Jurassic Coast Range ophiolite, Great Valley sequence, Franciscan Complex rocks, Miocene sedimentary rocks, and unconsolidated alluvium (Graymer and others, 2006). The contrasting magnetic and density properties of these rocks enable us to map their subsurface extent.

A potential new biosignature of life in iron-rich extreme environments: An iron (III) complex of scytonemin and proposal for its identification using Raman spectroscopy

NASA Astrophysics Data System (ADS)

Varnali, Tereza; Edwards, Howell G. M.

2013-07-01

Scytonemin is a cyanobacterial sheath pigment with potent UV absorbing (UV-A, UV-B and UV-C) properties. The importance of this biomolecule is its photoprotective function which is one of the major survival strategies adopted by extremophiles to combat high energy radiation insolation in environmentally stressed conditions. Also, iron (III) oxides offering an additional UV-protecting facility to subsurface biological colonization as well as banded iron formations with zones of iron depletion in rock matrices have attracted attention with special interest in the mobilisation and transportation of iron compounds through the rock. This study represents a novel proposal that an iron-scytonemin complex could facilitate the movement of iron through the subsurface rock as part of the this extremophilic survival strategy. The predicted Raman wavenumbers for the proposed scytonemin complex of iron(III) are derived computationally using DFT calculations. Comparison of the experimentally observed Raman spectra of scytonemin with the theoretically predicted Raman spectra of the iron-scytonemin complex show that the latter may be discriminated and the expected characteristic bands are reported in relation to structural changes that are effected upon complexation. This information will inform the future search for experimental evidence for an iron-scytonemin complex, which has not been recognised hitherto and which could provide a novel biosignature for the extremophilic colonization of terrestrial iron-rich geological matrices. Such a terrestrial scenario would be potentially of significance for the remote robotic analytical exploration of the iron-rich surface and immediate subsurface of Mars.

Advanced analysis of complex seismic waveforms to characterize the subsurface Earth structure

NASA Astrophysics Data System (ADS)

Jia, Tianxia

2011-12-01

This thesis includes three major parts, (1) Body wave analysis of mantle structure under the Calabria slab, (2) Spatial Average Coherency (SPAC) analysis of microtremor to characterize the subsurface structure in urban areas, and (3) Surface wave dispersion inversion for shear wave velocity structure. Although these three projects apply different techniques and investigate different parts of the Earth, their aims are the same, which is to better understand and characterize the subsurface Earth structure by analyzing complex seismic waveforms that are recorded on the Earth surface. My first project is body wave analysis of mantle structure under the Calabria slab. Its aim is to better understand the subduction structure of the Calabria slab by analyzing seismograms generated by natural earthquakes. The rollback and subduction of the Calabrian Arc beneath the southern Tyrrhenian Sea is a case study of slab morphology and slab-mantle interactions at short spatial scale. I analyzed the seismograms traversing the Calabrian slab and upper mantle wedge under the southern Tyrrhenian Sea through body wave dispersion, scattering and attenuation, which are recorded during the PASSCAL CAT/SCAN experiment. Compressional body waves exhibit dispersion correlating with slab paths, which is high-frequency components arrivals being delayed relative to low-frequency components. Body wave scattering and attenuation are also spatially correlated with slab paths. I used this correlation to estimate the positions of slab boundaries, and further suggested that the observed spatial variation in near-slab attenuation could be ascribed to mantle flow patterns around the slab. My second project is Spatial Average Coherency (SPAC) analysis of microtremors for subsurface structure characterization. Shear-wave velocity (Vs) information in soil and rock has been recognized as a critical parameter for site-specific ground motion prediction study, which is highly necessary for urban areas located in seismic active zones. SPAC analysis of microtremors provides an efficient way to estimate Vs structure. Compared with other Vs estimating methods, SPAC is noninvasive and does not require any active sources, and therefore, it is especially useful in big cities. I applied SPAC method in two urban areas. The first is the historic city, Charleston, South Carolina, where high levels of seismic hazard lead to great public concern. Accurate Vs information, therefore, is critical for seismic site classification and site response studies. The second SPAC study is in Manhattan, New York City, where depths of high velocity contrast and soil-to-bedrock are different along the island. The two experiments show that Vs structure could be estimated with good accuracy using SPAC method compared with borehole and other techniques. SPAC is proved to be an effective technique for Vs estimation in urban areas. One important issue in seismology is the inversion of subsurface structures from surface recordings of seismograms. My third project focuses on solving this complex geophysical inverse problems, specifically, surface wave phase velocity dispersion curve inversion for shear wave velocity. In addition to standard linear inversion, I developed advanced inversion techniques including joint inversion using borehole data as constrains, nonlinear inversion using Monte Carlo, and Simulated Annealing algorithms. One innovative way of solving the inverse problem is to make inference from the ensemble of all acceptable models. The statistical features of the ensemble provide a better way to characterize the Earth model.

Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (~33.5° S), using active seismic and electric methods

NASA Astrophysics Data System (ADS)

Díaz, D.; Maksymowicz, A.; Vargas, G.; Vera, E.; Contreras-Reyes, E.; Rebolledo, S.

2014-08-01

The crustal-scale west-vergent San Ramón thrust fault system, which lies at the foot of the main Andean Cordillera in central Chile, is a geologically active structure with manifestations of late Quaternary complex surface rupture on fault segments along the eastern border of the city of Santiago. From the comparison of geophysical and geological observations, we assessed the subsurface structural pattern that affects the sedimentary cover and rock-substratum topography across fault scarps, which is critical for evaluating structural models and associated seismic hazard along the related faults. We performed seismic profiles with an average length of 250 m, using an array of 24 geophones (Geode), with 25 shots per profile, to produce high-resolution seismic tomography to aid in interpreting impedance changes associated with the deformed sedimentary cover. The recorded travel-time refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both the velocities and the reflections that are interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps were used to construct subsurface resistivity tomographic profiles, which reveal systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, and clearly show well-defined east-dipping resistivity boundaries. These boundaries can be interpreted in terms of structurally driven fluid content change between the hanging wall and the footwall of the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ~55° E in the subsurface beneath the piedmont sediments, with local complexities likely associated with variations in fault surface rupture propagation, fault splays and fault segment transfer zones.

Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (∼33.5° S), using active seismic and electric methods

NASA Astrophysics Data System (ADS)

Díaz, D.; Maksymowicz, A.; Vargas, G.; Vera, E.; Contreras-Reyes, E.; Rebolledo, S.

2014-01-01

The crustal-scale west-vergent San Ramón thrust fault system at the foot of the main Andean Cordillera in central Chile is a geologically active structure with Quaternary manifestations of complex surface rupture along fault segments in the eastern border of Santiago city. From the comparison of geophysical and geological observations, we assessed the subsurface structure pattern affecting sedimentary cover and rock-substratum topography across fault scarps, which is critic for evaluating structural modeling and associated seismic hazard along this kind of faults. We performed seismic profiles with an average length of 250 m, using an array of twenty-four geophones (GEODE), and 25 shots per profile, supporting high-resolution seismic tomography for interpreting impedance changes associated to deformed sedimentary cover. The recorded traveltime refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both velocities and reflections interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps supported subsurface resistivity tomographic profiles, which revealed systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, clearly limited by well-defined east-dipping resistivity boundaries. The latter can be interpreted in terms of structurally driven fluid content-change between the hanging wall and the footwall of a permeability boundary associated with the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ∼55° E at subsurface levels in piedmont sediments, with local complexities being probably associated to fault surface rupture propagation, fault-splay and fault segment transfer zones.

iTOUGH2: A multiphysics simulation-optimization framework for analyzing subsurface systems

NASA Astrophysics Data System (ADS)

Finsterle, S.; Commer, M.; Edmiston, J. K.; Jung, Y.; Kowalsky, M. B.; Pau, G. S. H.; Wainwright, H. M.; Zhang, Y.

2017-11-01

iTOUGH2 is a simulation-optimization framework for the TOUGH suite of nonisothermal multiphase flow models and related simulators of geophysical, geochemical, and geomechanical processes. After appropriate parameterization of subsurface structures and their properties, iTOUGH2 runs simulations for multiple parameter sets and analyzes the resulting output for parameter estimation through automatic model calibration, local and global sensitivity analyses, data-worth analyses, and uncertainty propagation analyses. Development of iTOUGH2 is driven by scientific challenges and user needs, with new capabilities continually added to both the forward simulator and the optimization framework. This review article provides a summary description of methods and features implemented in iTOUGH2, and discusses the usefulness and limitations of an integrated simulation-optimization workflow in support of the characterization and analysis of complex multiphysics subsurface systems.

Stratigraphic and structural characterization of the OU-1 area at the former George Air Force Base, Adelanto, Southern California

USGS Publications Warehouse

Catchings, R.D.; Gandhok, G.; Goldman, M.R.

2001-01-01

The former George Air Force Base (GAFB), now known as the Southern California Logistics Airport (SCLA), is located in the town of Adelanto, approximately 100 km northeast of Los Angeles, California (Fig. 1). In this report, we present acquisition parameters, data, and interpretations of seismic images that were acquired in the OU-1 area of GAFB during July 1999 (Fig. 2). GAFB is scheduled for conversion to civilian use, however, during its years as an Air Force base, trichlorethylene (TCE) was apparently introduced into the subsurface as a result of spills during normal aircraft maintenance operations. To comply with congressional directives, TCE contaminant removal has been ongoing since the early-tomid 1990s. However, only a small percentage of the TCE believed to have been introduced into the subsurface has been recovered, due largely to difficulty in locating the TCE within the subsurface. Because TCE migrates within the subsurface by ground water movement, attempts to locate the TCE contaminants in the subsurface have employed an array of ground-water monitoring and extraction wells. These wells primarily sample within a shallow-depth (~40 m) aquifer system. Cores obtained from the monitoring and extraction wells indicate that the aquifer, which is composed of sand and gravel channels, is bounded by aquitards composed largely of clay and other fine-grained sediments. Based on well logs, the aquifer is about 3 to 5 m thick along the seismic profiles. A more thorough understanding of the lateral variations in the depth and thickness of the aquifer system may be a key to finding and removing the remaining TCE. However, due to its complex depositional and tectonic history, the structural and stratigraphic sequences are not easily characterized. An indication of the complex nature of the structure and stratigraphy is the appreciable variation in stratigraphic sequences observed in some monitoring wells that are only a few tens of meters apart. To better characterize the shallow (upper 100 m) stratigraphy beneath GAFB, the US Environmental Protection Agency (USEPA) contracted the US Geological Survey (USGS) to acquire three seismic reflection/refraction profiles within an area known as Operational Unit #1 (OU-1). The principal objective of the seismic survey was to laterally characterize the subsurface with respect to structure and stratigraphy. In particular, we desired to (1) laterally “map” stratigraphic units (particularly aquifer layers) that were previously identified in monitoring wells within the OU-1 area and (2) identify structures, such as faults and folds, that affect the movement of ground water. Knowledge of lateral variations in stratigraphic units and structures that may affect those units is useful in constructing ground-water flow models, which aid in identifying possible TCE migration paths within the subsurface. Stratigraphic and structural characterization may also be useful in identifying surface locations and target depths for future wells (Catchings et al., 1996). Proper siting of wells is important because a welldefined aquifer is apparently not present in all locations at GAFB, as indicated by lithologic logs from existing wells (Montgomery Watson, 1995). Proper depth placement of monitoring and extraction wells is important because wells that are too shallow will not sample within the aquifer, and wells that are too deep risk puncturing the aquitard and allowing contaminants to flow to deeper levels.

Permeability structure of a highly heterogeneous transgressive-marine complex: Tocito Sandstone, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, M.L.; Cole, R.D.

1996-01-01

The Tocito Sandstone Member of the Mancos Shale is an Upper Cretaceous shallow-marine sandstone and mudrock complex deposited along the western margin of the Western Interior seaway. The Tocito is a major hydrocarbon producer in the San Juan Basin (approximately 117 million barrels of oil and 79 billion cubic feet of gas). Because of reservoir heterogeneity, ultimate Tocito oil recovery factors are low, generally between 10 and 20 percent. To enhance understanding of permeability heterogeneity in the Tocito, we have undertaken a detailed surface and subsurface investigation. A total of 2,697 permeability measurements have been made using minipermeameters. Permeability variationmore » within the Tocito is controlled by two principal factors: lithofacies and burial/diagenetic history. Coarser grained and better sorted lithofacies have the highest permeability. The permeability values from outcrop and shallow subsurface cores are dramatically higher than those from deep subsurface cores. This is due to dissolution of grains and calcite cement, and decompaction that preferentially affected the outcrop and shallow subsurface. Correlation lengths for permeability values along horizontal transacts are typically less than 3 m, whereas those for vertical transacts are usually less than 0.6 m. These data suggest that small grid block sizes should be used during reservoir simulations if the investigator wishes to accurately capture the reservoir heterogeneity.« less

Permeability structure of a highly heterogeneous transgressive-marine complex: Tocito Sandstone, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, M.L.; Cole, R.D.

1996-12-31

The Tocito Sandstone Member of the Mancos Shale is an Upper Cretaceous shallow-marine sandstone and mudrock complex deposited along the western margin of the Western Interior seaway. The Tocito is a major hydrocarbon producer in the San Juan Basin (approximately 117 million barrels of oil and 79 billion cubic feet of gas). Because of reservoir heterogeneity, ultimate Tocito oil recovery factors are low, generally between 10 and 20 percent. To enhance understanding of permeability heterogeneity in the Tocito, we have undertaken a detailed surface and subsurface investigation. A total of 2,697 permeability measurements have been made using minipermeameters. Permeability variationmore » within the Tocito is controlled by two principal factors: lithofacies and burial/diagenetic history. Coarser grained and better sorted lithofacies have the highest permeability. The permeability values from outcrop and shallow subsurface cores are dramatically higher than those from deep subsurface cores. This is due to dissolution of grains and calcite cement, and decompaction that preferentially affected the outcrop and shallow subsurface. Correlation lengths for permeability values along horizontal transacts are typically less than 3 m, whereas those for vertical transacts are usually less than 0.6 m. These data suggest that small grid block sizes should be used during reservoir simulations if the investigator wishes to accurately capture the reservoir heterogeneity.« less

Absorption spectroscopic studies of Np(IV) complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, D. T.

2004-01-01

The complexation of neptunium (IV) with selected inorganic and organic ligands was studied as part of an investigation to establish key subsurface interactions between neptunium and biological systems. The prevalence of reducing environments in most subsurface migation scenarios, which are in many cases induced by biological activity, has increased the role and importance of Np(IV) as a key subsurface neptunium oxidation state. The biodegradation of larger organics that often coexist with actinides in the subsurface leads to the formation of many organic acids as transient products that, by complexation, play a key role in defining the fate and speciation ofmore » neptunium in biologically active systems. These often compete with inorganic complexes e.g. hydrolysis and phosphate. Herein we report the results of a series of complexation studies based on new band formation of the characteristic 960 nm band for Np(IV). Formation constants for Np(IV) complexes with phosphate, hydrolysis, succinate, acetohydroxamic acid, and acetate were determined. These results show the 960 nm absorption band to be very amenable to these types of complexation studies.« less

Tectonosedimentary framework of Upper Cretaceous -Neogene series in the Gulf of Tunis inferred from subsurface data: implications for petroleum exploration

NASA Astrophysics Data System (ADS)

Dhraief, Wissem; Dhahri, Ferid; Chalwati, Imen; Boukadi, Noureddine

2017-04-01

The objective and the main contribution of this issue are dedicated to using subsurface data to delineate a basin beneath the Gulf of Tunis and its neighbouring areas, and to investigate the potential of this area in terms of hydrocarbon resources. Available well data provided information about the subsurface geology beneath the Gulf of Tunis. 2D seismic data allowed delineation of the basin shape, strata geometries, and some potential promising subsurface structures in terms of hydrocarbon accumulation. Together with lithostratigraphic data obtained from drilled wells, seismic data permitted the construction of isochron and isobath maps of Upper Cretaceous-Neogene strata. Structural and lithostratigraphic interpretations indicate that the area is tectonically complex, and they highlight the tectonic control of strata deposition during the Cretaceous and Neogene. Tectonic activity related to the geodynamic evolution of the northern African margin appears to have been responsible for several thickness and facies variations, and to have played a significant role in the establishment and evolution of petroleum systems in northeastern Tunisia. As for petroleum systems in the basin, the Cretaceous series of the Bahloul, Mouelha and Fahdene formations are acknowledged to be the main source rocks. In addition, potential reservoirs (Fractured Abiod and Bou Dabbous carbonated formations) sealed by shaly and marly formations (Haria and Souar formations respectively) show favourable geometries of trap structures (anticlines, tilted blocks, unconformities, etc.) which make this area adequate for hydrocarbon accumulations.

Qualitative analysis of MTEM response using instantaneous attributes

NASA Astrophysics Data System (ADS)

Fayemi, Olalekan; Di, Qingyun

2017-11-01

This paper introduces new technique for qualitative analysis of multi-transient electromagnetic (MTEM) earth impulse response over complex geological structures. Instantaneous phase and frequency attributes were used in place of the conventional common offset section for improved qualitative interpretation of MTEM data by obtaining more detailed information from the earth impulse response. The instantaneous attributes were used to describe the lateral variation in subsurface resistivity and the visible geological structure with respect to given offsets. Instantaneous phase attribute was obtained by converting the impulse response into a complex form using the Hilbert transform. Conversely, the polynomial phase difference (PPD) estimator was favored over the center finite difference (CFD) approximation method in calculating the instantaneous frequency attribute because it is computationally efficient and has the ability to give a smooth variation of the instantaneous frequency over a common offset section. The observed results from the instantaneous attributes were in good agreement with both the subsurface model used and the apparent resistivity section obtained from the MTEM earth impulse response. Hence, this study confirms the capability of both instantaneous phase and frequency attributes as highly effective tools for MTEM qualitative analysis.

Calibration of Complex Subsurface Reaction Models Using a Surrogate-Model Approach

EPA Science Inventory

Application of model assessment techniques to complex subsurface reaction models involves numerous difficulties, including non-trivial model selection, parameter non-uniqueness, and excessive computational burden. To overcome these difficulties, this study introduces SAMM (Simult...

CALIBRATION OF SUBSURFACE BATCH AND REACTIVE-TRANSPORT MODELS INVOLVING COMPLEX BIOGEOCHEMICAL PROCESSES

EPA Science Inventory

In this study, the calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes was systematically evaluated. Two hypothetical nitrate biodegradation scenarios were developed and simulated in numerical experiments to evaluate the perfor...

Real rock-microfluidic flow cell: A test bed for real-time in situ analysis of flow, transport, and reaction in a subsurface reactive transport environment.

PubMed

Singh, Rajveer; Sivaguru, Mayandi; Fried, Glenn A; Fouke, Bruce W; Sanford, Robert A; Carrera, Martin; Werth, Charles J

2017-09-01

Physical, chemical, and biological interactions between groundwater and sedimentary rock directly control the fundamental subsurface properties such as porosity, permeability, and flow. This is true for a variety of subsurface scenarios, ranging from shallow groundwater aquifers to deeply buried hydrocarbon reservoirs. Microfluidic flow cells are now commonly being used to study these processes at the pore scale in simplified pore structures meant to mimic subsurface reservoirs. However, these micromodels are typically fabricated from glass, silicon, or polydimethylsiloxane (PDMS), and are therefore incapable of replicating the geochemical reactivity and complex three-dimensional pore networks present in subsurface lithologies. To address these limitations, we developed a new microfluidic experimental test bed, herein called the Real Rock-Microfluidic Flow Cell (RR-MFC). A porous 500μm-thick real rock sample of the Clair Group sandstone from a subsurface hydrocarbon reservoir of the North Sea was prepared and mounted inside a PDMS microfluidic channel, creating a dynamic flow-through experimental platform for real-time tracking of subsurface reactive transport. Transmitted and reflected microscopy, cathodoluminescence microscopy, Raman spectroscopy, and confocal laser microscopy techniques were used to (1) determine the mineralogy, geochemistry, and pore networks within the sandstone inserted in the RR-MFC, (2) analyze non-reactive tracer breakthrough in two- and (depth-limited) three-dimensions, and (3) characterize multiphase flow. The RR-MFC is the first microfluidic experimental platform that allows direct visualization of flow and transport in the pore space of a real subsurface reservoir rock sample, and holds potential to advance our understandings of reactive transport and other subsurface processes relevant to pollutant transport and cleanup in groundwater, as well as energy recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

Siting of prison complex above abandoned underground coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marino, G.G.

1998-10-01

This paper discusses in detail the process undertaken to mitigate the effects of any future mine subsidence on prison structures proposed above old abandoned underground workings. The site for a proposed prison complex purchased by the state of Indiana was located in west-central Indiana and was undermined by an old abandoned room and pillar mine. Based on a study of the mine map and subsurface verification of the extent of mining it was determined that all prison buildings and important structures could be placed above solid coal to the north. However, one masonry building was located within the potential drawmore » zone of mine works that still contained significant mine voids. Based on empirical data the subsidence potential was estimated and the building was designed accordingly to be mine subsidence resistant. It was decided that a phase 2 prison complex should be constructed adjacent to and just south of the phase 1 complex. This complex would be directly above the underground workings. Subsequently, an extensive subsurface investigation program was undertaken to (1) ascertain whether or not mine areas where buildings would be located were already collapsed and thus only nominal, if any, subsidence could occur in the future and (2) verify the presence of solid coal areas within the mine as indicated on the mine map. Based on all the site information gathered subsidence profiles were developed from an empirical database of subsidence events in the Illinois coal basin. As a result of this work many structures on the site required no or nominal subsidence considerations. However, for others that could be affected potentially by future subsidence movement preliminary subsidence resistant designs were completed using the expected level of potential subsidence movement.« less

Subsurface structural interpretation by applying trishear algorithm: An example from the Lenghu5 fold-and-thrust belt, Qaidam Basin, Northern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Pei, Yangwen; Paton, Douglas A.; Wu, Kongyou; Xie, Liujuan

2017-08-01

The application of trishear algorithm, in which deformation occurs in a triangle zone in front of a propagating fault tip, is often used to understand fault related folding. In comparison to kink-band methods, a key characteristic of trishear algorithm is that non-uniform deformation within the triangle zone allows the layer thickness and horizon length to change during deformation, which is commonly observed in natural structures. An example from the Lenghu5 fold-and-thrust belt (Qaidam Basin, Northern Tibetan Plateau) is interpreted to help understand how to employ trishear forward modelling to improve the accuracy of seismic interpretation. High resolution fieldwork data, including high-angle dips, 'dragging structures', thinning hanging-wall and thickening footwall, are used to determined best-fit trishear model to explain the deformation happened to the Lenghu5 fold-and-thrust belt. We also consider the factors that increase the complexity of trishear models, including: (a) fault-dip changes and (b) pre-existing faults. We integrate fault dip change and pre-existing faults to predict subsurface structures that are apparently under seismic resolution. The analogue analysis by trishear models indicates that the Lenghu5 fold-and-thrust belt is controlled by an upward-steepening reverse fault above a pre-existing opposite-thrusting fault in deeper subsurface. The validity of the trishear model is confirmed by the high accordance between the model and the high-resolution fieldwork. The validated trishear forward model provides geometric constraints to the faults and horizons in the seismic section, e.g., fault cutoffs and fault tip position, faults' intersecting relationship and horizon/fault cross-cutting relationship. The subsurface prediction using trishear algorithm can significantly increase the accuracy of seismic interpretation, particularly in seismic sections with low signal/noise ratio.

Effectiveness of Hydraulic Parameterization Strategies for Simulating Moisture Dynamics in a Deep Semi-Arid Vadose Zone

NASA Astrophysics Data System (ADS)

Zhang, Y.; Schaap, M. G.

2012-12-01

Over the past fifteen years, the University of Arizona has carried out four controlled infiltration experiments in a 3600 m2, 15 meter deep vadose zone (Maricopa, Arizona) in which the evolution of moisture content (9 wells, 25 cm resolution), and matric potential (27 locations) was monitored and the subsurface stratigraphy, texture (1042 samples), and bulk density (251 samples) was characterized. In order to simulate the subsurface moisture dynamics it is necessary to define the 3D structure of the subsurface hydraulic characteristics (i.e. moisture retention and hydraulic functions). Several simple to complex strategies are possible ranging from stratigraphy based layering using hydraulic parameters derived from core samples to sophisticated numerical inversions based on 3D geostatistics and site-specific pedotransfer functions. A range of approaches will be evaluated on objective metrics that quantify how well the observed moisture dynamics are matched by simulations. We will evaluate the worth of auxiliary data such as observed matric potentials and quantity the number of texture samples needed to arrive at effective descriptions of subsurface structure. In addition, we will discuss more subjective metrics that evaluate the relative effort involved and estimate monetary cost of each method. While some of the results will only be valid for the studied site, some general conclusions will be possible about the effectiveness of particular methods for other semi-arid sites.

a Comparative Case Study of Reflection Seismic Imaging Method

NASA Astrophysics Data System (ADS)

Alamooti, M.; Aydin, A.

2017-12-01

Seismic imaging is the most common means of gathering information about subsurface structural features. The accuracy of seismic images may be highly variable depending on the complexity of the subsurface and on how seismic data is processed. One of the crucial steps in this process, especially in layered sequences with complicated structure, is the time and/or depth migration of seismic data.The primary purpose of the migration is to increase the spatial resolution of seismic images by repositioning the recorded seismic signal back to its original point of reflection in time/space, which enhances information about complex structure. In this study, our objective is to process a seismic data set (courtesy of the University of South Carolina) to generate an image on which the Magruder fault near Allendale SC can be clearly distinguished and its attitude can be accurately depicted. The data was gathered by common mid-point method with 60 geophones equally spaced along an about 550 m long traverse over a nearly flat ground. The results obtained from the application of different migration algorithms (including finite-difference and Kirchhoff) are compared in time and depth domains to investigate the efficiency of each algorithm in reducing the processing time and improving the accuracy of seismic images in reflecting the correct position of the Magruder fault.

Method of imaging the electrical conductivity distribution of a subsurface

DOEpatents

Johnson, Timothy C.

2017-09-26

A method of imaging electrical conductivity distribution of a subsurface containing metallic structures with known locations and dimensions is disclosed. Current is injected into the subsurface to measure electrical potentials using multiple sets of electrodes, thus generating electrical resistivity tomography measurements. A numeric code is applied to simulate the measured potentials in the presence of the metallic structures. An inversion code is applied that utilizes the electrical resistivity tomography measurements and the simulated measured potentials to image the subsurface electrical conductivity distribution and remove effects of the subsurface metallic structures with known locations and dimensions.

Crystal structure of laser-induced subsurface modifications in Si

NASA Astrophysics Data System (ADS)

Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.; Haberl, B.; Bradby, J. E.; Williams, J. S.; Huis in't Veld, A. J.

2015-08-01

Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this work, we investigate the geometry and crystal structure of laser-induced subsurface modifications in monocrystalline silicon wafers. In addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si -iii/Si -xii occur as a result of the laser irradiation.

The siting of a prison complex above an abandoned underground coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marino, G.G.

1997-12-31

This paper discusses in detail the process undertaken to mitigate the effects of any future mine subsidence on prison structures proposed above old abandoned underground workings. The site for a proposed prison complex purchased by the State of Indiana was located in west-central Indiana and was undermined by an old abandoned room and pillar mine. The original plan for construction consisted of one phase. Based on a study of the mine map and subsurface verification of the extent of mining it was determined that all prison buildings and important structures could be placed above solid coal to the north. Onemore » masonry building, however, was located within the potential draw zone of mine works which still contained significant mine voids. Based on empirical data the subsidence potential was estimated and the building was accordingly designed to be mine subsidence resistant. It was decided that a phase two prison complex should be constructed adjacent to and just south of the Phase I complex. This complex would be directly above the underground workings. The first stage of design was to minimize subsidence potential by positioning the exposure of significant structures to the subjacent mining assuming the mine map was sufficiently accurate. Subsequently, an extensive subsurface investigation program was then undertaken to: (1) ascertain whether or not mine areas where buildings would be located were already collapsed and thus only nominal, if any, subsidence could occur in the future; and (2) verify the presence of solid coal areas within the mine as indicated on the mine map. Based on all the site information gathered subsidence profiles were developed from an empirical data base of subsidence events in the Illinois Coal Basin. As a result of this work many structures on the site required no or nominal subsidence considerations.« less

Crystal structure of laser-induced subsurface modifications in Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.

2015-06-04

Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this paper, we investigate the geometry and crystalmore » structure of laser-induced subsurface modifications in monocrystalline silicon wafers. Finally, in addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si-iii/Si-xii occur as a result of the laser irradiation.« less

Subsurface and terrain controls on runoff generation in deep soil landscapes

NASA Astrophysics Data System (ADS)

Mallard, John; McGlynn, Brian; Richter, Daniel

2017-04-01

Our understanding of runoff generation in regions characterized by deep, highly weathered soils is incomplete despite the prevalence of this setting worldwide. To address this, we instrumented a first-order watershed in the Piedmont of South Carolina, USA. The Piedmont region of the United States extends east of the Appalachians from Maryland to Alabama, and is home to some of the most rapid population growth in the country. Regional and local relief is modest, although the landscape is highly dissected and local slope can be quite variable. The region's soils are ancient, deeply weathered, and characterized by sharp changes in hydrologic properties due to concentration of clay in the Bt horizon. Despite a mild climate and consistent precipitation, seasonally variable energy availability and deciduous tree cover create a strong evapotranspiration mediated seasonal hydrologic dynamic: while moist soils and extended stream networks are typical of the late fall through spring, relatively dry soils and contracting stream networks emerge in the summer and early fall. To elucidate the control of the complex vertical and planform structure of this region, as well as the strongly seasonal subsurface hydrology, on runoff generation, we installed a network of nested, shallow groundwater wells across an ephemeral to first-order watershed to continuously measure internal water levels. We also recorded local precipitation and discharge at the outlet of this watershed, a similar adjacent watershed, and in the second to third order downstream watershed. Subsurface water dynamics varied spatially, vertically, and seasonally. Shallow depths and landscape positions with minimal contributing area exhibited flashier dynamics comparable to the stream hydrographs while positions with more contributing area exhibited relatively muted dynamics. Most well positions showed minimal response to precipitation throughout the summer, and even occasionally observed response rarely co-occurred with streamflow generation. Our initial findings suggest that characterizing the terrain of a watershed must be coupled with the subsurface soil hydrology in order to understand spatiotemporal patterns of streamflow generation in regions possessing both complex vertical structure and terrain.

Preliminary Studies of the Structural Characteristics of the Lubao Fault using 2D High Resolution Shallow Seismic Reflection Profile

NASA Astrophysics Data System (ADS)

Bonus, A. A. B.; Lagmay, A. M. A.; Rodolfo, K. S.

2016-12-01

The Lubao fault, located in the province of Pampanga, Philippines, is part of the Bataan Volcanic Arc Complex (BVAC). Active faults within and around the BVAC include the East Zambales and Iba faults; according to the official active faults map of the Philippine Institute of Volcanology and Seismology (PHIVOLCS) there are no other existing active faults in the area. The Lubao Fault distinctly separates wetlands to the northeast and dry alluvial plains to the northwest of Manila Bay. Long term subsidence and high sedimentation rates were observed in the fault and over the past 1.5 thousand years, the northeastern block has dropped 3.5 meters. Along the southwest flank of Mount Natib, tectonic structures were identified using surface mapping and remote sensing. The Persistent Scattering Interferometric Synthetic Aperture Radar (PSInSAR) data results of Eco et al. in 2015 shows uplifts and subsidence in the BVAC area delineating the Lubao Fault. A 480-meter seismic reflection line was laid down perpendicular to the fault with a recording system consisting of 48 channels of Geometrics geophones spaced 10 meters apart. Acquired data were processed using the standard seismic reflection processing sequence by Yilmaz 2001. This preliminary study produced a high resolution subsurface profile of the Lubao fault in the village of San Rafael, Lubao where it is well manifested. The velocity model integrated by stratigraphic data of drilled core shows subsurface lithology. The depth converted profile reveals clear structures and dipping segments which indicates a history of movement along the Lubao fault. Discontinuity of reflectors, either offsets or breaks, are considered structures along the subsurface of the study area. Additional structural mapping and seismic lines along the projected fault are planned in the future to further detail the characteristics of the Lubao Fault. The surface observations made by other researchers coupled with the subsurface seismic profile mapping of this study hopes to clearly delineate and characterize the Lubao Fault.

How deep can surface signals be traced in the critical zone? Merging biodiversity with biogeochemistry research in a central German Muschelkalk landscape

NASA Astrophysics Data System (ADS)

Küsel, Kirsten; Totsche, Kai; Trumbore, Susan; Lehmann, Robert; Steinhäuser, Christine; Herrmann, Martina

2016-04-01

The Earth's Critical Zone (CZ) is a thin living layer connecting atmosphere and geosphere, including aquifers. Humans live in the CZ and benefit from the vital supporting services it provides. However, the CZ is increasingly impacted by human activities including land and resource use, pollution and climate change. Recent interest in uniting the many disciplines studying this complex domain has initiated an international network of research infrastructure platforms that allow access to the CZ in a range of geologic settings. In this paper a new such infrastructure platform associated with the Collaborative Research Center AquaDiva is described, that uniquely seeks to combine CZ research with detailed investigation of the functional biodiversity of the subsurface. Overall, AquaDiva aims to test hypotheses about how water connects surface conditions set by land cover and land management to the biota and biogeochemical functions in the subsurface. With long-term and continuous observations, hypotheses about how seasonal variations and extreme events at the surface impact subsurface processes, community structure and function, are tested. AquaDiva has established the Hainich Critical Zone Exploratory (CZE) in central Germany in an alkaline geological setting of German Triassic Muschelkalk formations. The Hainich CZE includes specialized monitoring wells to access the vadose zone and two main groundwater complexes in limestone and marlstone parent materials along a ~6 km transect spanning forest, pasture and agricultural land uses. Initial results demonstrate fundamental differences in the biota and biogeochemistry of the two aquifer complexes that trace back to the land uses in their respective recharge areas. They also show the importance of antecedent conditions on the impact of precipitation events on responses in terms of groundwater dynamics, chemistry and ecology. Thus we find signals of surface land use and events can be detected in the subsurface CZ. Future research will expand to a second CZE in contrasting siliciclastic parent rock, to evaluate the relative importance of parent material lithology versus surface conditions for the emergent characteristics of the subsurface CZ and biodiversity. The Hainich CZE is open to researchers who bring new questions that the research platform can help answer.

Preliminary Study of 2-D Time Domain Electromagnetic (TDEM) Modeling to Analyze Subsurface Resistivity Distribution and its Application to the Geothermal Systems

NASA Astrophysics Data System (ADS)

Aji Hapsoro, Cahyo; Purqon, Acep; Srigutomo, Wahyu

2017-07-01

2-D Time Domain Electromagnetic (TDEM) has been successfully conducted to illustrate the value of Electric field distribution under the Earth surface. Electric field compared by magnetic field is used to analyze resistivity and resistivity is one of physical properties which very important to determine the reservoir potential area of geothermal systems as one of renewable energy. In this modeling we used Time Domain Electromagnetic method because it can solve EM field interaction problem with complex geometry and to analyze transient problems. TDEM methods used to model the value of electric and magnetic fields as a function of the time combined with the function of distance and depth. The result of this modeling is Electric field intensity value which is capable to describe the structure of the Earth’s subsurface. The result of this modeling can be applied to describe the Earths subsurface resistivity values to determine the reservoir potential of geothermal systems.

The Dual Role of Vegetation as a Constraint on Mass and Energy Flux into the Critical Zone and as an Emergent Property of Geophysical Critical Zone Structure

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Swetnam, T. L.; Barnard, H. R.; Singha, K.; Harpold, A.; Litvak, M. E.

2017-12-01

Spatial patterns in vegetation long have been used to scale both landsurface-atmosphere exchanges of water and carbon as well as to infer subsurface structure. These pursuits typical proceed in isolation and rarely do inferences gained from one community propagate to related efforts in another. Perhaps more importantly, vegetation often is treated as an emergent property of landscape-climate interactions rather than an active modifier of both critical zone structure and energy fluxes. We posit that vegetation structure and activity are under utilized as a tool towards understanding landscape evolution and present examples that begin to disentangle the role of vegetation as both an emergent property and an active control on critical zone structure and function. As climate change, population growth, and land use changes threaten water resources worldwide, the need for the new insights vegetation can provide becomes not just a basic science priority, but a pressing applied science question with clear societal importance. This presentation will provide an overview of recent efforts to address the dual role of vegetation in both modifying and reflecting critical zone structure in the western North American forests. For example, interactions between topography and stand scale vegetation structure influence both solar radiation and turbulence altering landscape scale partitioning of evaporation vs transpiration with major impacts of surface water supply. Similarly, interactions between topographic shading, lateral redistribution of plant available water, and subsurface storage create a mosaic of drought resistance and resilience across complex terrain. These complex interactions between geophysical and vegetation components of critical zone structure result in predictable patterns in catchment scale hydrologic partitioning within individual watersheds while simultaneously suggesting testable hypotheses for why catchments under similar climate regimes respond so differently to drought stress.

Vertical Subsurface Flow Mixing and Horizontal Anisotropy in Coarse Fluvial Aquifers: Structural Aspects

NASA Astrophysics Data System (ADS)

Huggenberger, P.; Huber, E.

2014-12-01

Detailed descriptions of the subsurface heterogeneities in coarse fluvial aquifer gravel often lack in concepts to distinguish between the essence and the noise of a permeability structure and the ability to extrapolate site specific hydraulic information at the tens to several hundred meters scale. At this scale the heterogeneity strongly influences the anisotropies of the flow field and the mixing processes in groundwater. However, in many hydrogeological models the complexity of natural systems is oversimplified. Understanding the link between the dynamics of the surface processes of braided-river systems and the resulting subsurface sedimentary structures is the key to characterizing the complexity of horizontal and vertical mixing processes in groundwater. From the different depositional elements of coarse braided-river systems, the largest permeability contrasts can be observed in the scour-fills. Other elements (e.g. different types of gravel sheets) show much smaller variabilities and could be considered as a kind of matrix. Field experiments on the river Tagliamento (Northeast Italy) based on morphological observation and ground-penetrating radar (GPR) surveys, as well as outcrop analyses of gravel pit exposures (Switzerland) allowed us to define the shape, sizes, spatial distribution and preservation potential of scour-fills. In vertical sections (e.g. 2D GPR data, vertical outcrop), the spatial density of remnant erosional bounding surfaces of scours is an indicator for the dynamics of the braided-river system (lateral mobility of the active floodplain, rate of sediment net deposition and spatial distribution of the confluence scours). In case of combined low aggradation rate and low lateral mobility the deposits may be dominated by a complex overprinting of scour-fills. The delineation of the erosional bounding surfaces, that are coherent over the survey area, is based on the identification of angular discontinuities of the reflectors. Fence diagrams and horizontal time-slices from GPR data are used to construct simplified 3D hydraulic properties distribution models and to derive anisotropy patterns. On the basis of this work, conceptual models could be designed and implemented into numerical models to simulate the flow field and mixing in heterogeneous braided-river deposits.

The thermal impact of subsurface building structures on urban groundwater resources - A paradigmatic example.

PubMed

Epting, Jannis; Scheidler, Stefan; Affolter, Annette; Borer, Paul; Mueller, Matthias H; Egli, Lukas; García-Gil, Alejandro; Huggenberger, Peter

2017-10-15

Shallow subsurface thermal regimes in urban areas are increasingly impacted by anthropogenic activities, which include infrastructure development like underground traffic lines as well as industrial and residential subsurface buildings. In combination with the progressive use of shallow geothermal energy systems, this results in the so-called subsurface urban heat island effect. This article emphasizes the importance of considering the thermal impact of subsurface structures, which commonly is underestimated due to missing information and of reliable subsurface temperature data. Based on synthetic heat-transport models different settings of the urban environment were investigated, including: (1) hydraulic gradients and conductivities, which result in different groundwater flow velocities; (2) aquifer properties like groundwater thickness to aquitard and depth to water table; and (3) constructional features, such as building depths and thermal properties of building structures. Our results demonstrate that with rising groundwater flow velocities, the heat-load from building structures increase, whereas down-gradient groundwater temperatures decrease. Thermal impacts on subsurface resources therefore have to be related to the permeability of aquifers and hydraulic boundary conditions. In regard to the urban settings of Basel, Switzerland, flow velocities of around 1 md -1 delineate a marker where either down-gradient temperature deviations or heat-loads into the subsurface are more relevant. Furthermore, no direct thermal influence on groundwater resources should be expected for aquifers with groundwater thicknesses larger 10m and when the distance of the building structure to the groundwater table is higher than around 10m. We demonstrate that measuring temperature changes down-gradient of subsurface structures is insufficient overall to assess thermal impacts, particularly in urban areas. Moreover, in areas which are densely urbanized, and where groundwater flow velocities are low, appropriate measures for assessing thermal impacts should specifically include a quantification of heat-loads into the subsurface which result in a more diffuse thermal contamination of urban groundwater resources. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluating Predictive Uncertainty of Hyporheic Exchange Modelling

NASA Astrophysics Data System (ADS)

Chow, R.; Bennett, J.; Dugge, J.; Wöhling, T.; Nowak, W.

2017-12-01

Hyporheic exchange is the interaction of water between rivers and groundwater, and is difficult to predict. One of the largest contributions to predictive uncertainty for hyporheic fluxes have been attributed to the representation of heterogeneous subsurface properties. This research aims to evaluate which aspect of the subsurface representation - the spatial distribution of hydrofacies or the model for local-scale (within-facies) heterogeneity - most influences the predictive uncertainty. Also, we seek to identify data types that help reduce this uncertainty best. For this investigation, we conduct a modelling study of the Steinlach River meander, in Southwest Germany. The Steinlach River meander is an experimental site established in 2010 to monitor hyporheic exchange at the meander scale. We use HydroGeoSphere, a fully integrated surface water-groundwater model, to model hyporheic exchange and to assess the predictive uncertainty of hyporheic exchange transit times (HETT). A highly parameterized complex model is built and treated as `virtual reality', which is in turn modelled with simpler subsurface parameterization schemes (Figure). Then, we conduct Monte-Carlo simulations with these models to estimate the predictive uncertainty. Results indicate that: Uncertainty in HETT is relatively small for early times and increases with transit times. Uncertainty from local-scale heterogeneity is negligible compared to uncertainty in the hydrofacies distribution. Introducing more data to a poor model structure may reduce predictive variance, but does not reduce predictive bias. Hydraulic head observations alone cannot constrain the uncertainty of HETT, however an estimate of hyporheic exchange flux proves to be more effective at reducing this uncertainty. Figure: Approach for evaluating predictive model uncertainty. A conceptual model is first developed from the field investigations. A complex model (`virtual reality') is then developed based on that conceptual model. This complex model then serves as the basis to compare simpler model structures. Through this approach, predictive uncertainty can be quantified relative to a known reference solution.

Shallow Subsurface Structures of Volcanic Fissures

NASA Astrophysics Data System (ADS)

Parcheta, C. E.; Nash, J.; Mitchell, K. L.; Parness, A.

2015-12-01

Volcanic fissure vents are a difficult geologic feature to quantify. They are often too thin to document in detail with seismology or remote geophysical methods. Additionally, lava flows, lava drain back, or collapsed rampart blocks typically conceal a fissure's surface expression. For exposed fissures, quantifying the surface (let along sub0surface) geometric expression can become an overwhelming and time-consuming task given the non-uniform distribution of wall irregularities, drain back textures, and the larger scale sinuosity of the whole fissure system. We developed (and previously presented) VolcanoBot to acquire robust characteristic data of fissure geometries by going inside accessible fissures after an eruption ends and the fissure cools off to <50 C. Data from VolcanoBot documents the fissure conduit geometry with a near-IR structured light sensor, and reproduces the 3d structures to cm-scale accuracy. Here we present a comparison of shallow subsurface structures (<30 m depth) within the Mauna Ulu fissure system and their counterpart features at the vent-to-ground-surface interface. While we have not mapped enough length of the fissure to document sinuosity at depth, we see a self-similar pattern of irregularities on the fissure walls throughout the entire shallow subsurface, implying a fracture mechanical origin similar to faults. These irregularities are, on average, 1 m across and protrude 30 cm into the drained fissure. This is significantly larger than the 10% wall roughness addressed in the engineering literature on fluid dynamics, and implies that magma fluid dynamics during fissure eruptions are probably not as passive nor as simple as previously thought. In some locations, it is possible to match piercing points across the fissure walls, where the dike broke the wall rock in order to propagate upwards, yet in other locations there are erosional cavities, again, implying complex fluid dynamics in the shallow sub-surface during fissure eruptions.

Complex carbonate and clastic stratigraphy of the inner shelf off west-central Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Locker, S.D.; Doyle, L.J.; Hine, A.C.

1990-05-01

The near surface stratigraphy (< 30 m) of the inner shelf off the west coast of Florida was investigated using high-resolution seismic, side-scan sonar, and continuous underwater video camera coverage. The simultaneous operation of all three systems provided a unique opportunity to calibrate acoustic data with actual video images of the sea floor in a geologically complex area characterized by limestone dissolution structures, hard-bottom exposures, and overlain by a limited supply of terrigenous clastics. Three principle bottom types, grass, sand, and hard-bottom mapped using video and side-scan sonographs, show a correlation with two subsurface stratigraphic zones. The nearshore subsurface zonemore » extending to 6-7 m water depth is characterized by flat or rolling strata and sinkholes that increase in size (200-1,200 m in diameter) and become more numerous further offshore. This zone is truncated by a major erosional unconformity overlain by a thin (<3 m) sequence of Holocene sediment, which together form a terrace upon which the Anclote Key barrier island formed. The offshore subsurface zone (7-11 m water depth) exhibits irregular and discontinuous high-amplitude flat or inclined reflections and few sinkholes. Offshore, extensive hard-bottom exposures are common with discontinuous sediment that occur as lenses or sand waves. The complex stratigraphy of the west Florida shelf includes outcropping Neogene limestones that have undergone dissolution during sea level lowstands. Carbonates and clastics dispersed during multiple sea level changes overlie the Neogene limestones. Dissolution styles and erosional unconformities produced bedrock topography and now control modern geological and biological processes.« less

Investigation of lunar maria structure from cross-analysis of GRAIL gravity and Kaguya radar data

NASA Astrophysics Data System (ADS)

Zuber, M. T.; Ermakov, A.; Smith, D. E.; Mastroguiseppe, M.; Raguso, M.

2016-12-01

The Lunar Radar Sounder (LRS) on JAXA's Kaguya spacecraft investigated the subsurface structure of the Moon to a depth of a few km. GRAIL gravity models are potentially sensitive to subsurface structure at such depths. GRAIL gravity and LRS radar data are complementary since both are sensitive to density/compositional heterogeneities. Cross-correlation of GRAIL and LRS data has the potential to produce new constraints on the structure and evolution of the lunar maria. Originally, subsurface reflections within the lunar maria were detected with Lunar Sounder Experiment aboard Apollo 17. Subsurface layering was attributed to multiple episodes of volcanism. Later, Kaguya's LRS produced similar measurements but with global-scale coverage. Laboratory measurements show that density variations among mare basalts can be up to 200 kg m-3 or 7%. The LRS measurements have detected subsurface reflection in the upper 1 km of the crust. Combining these two estimates and using the Bouguer slab approximation, we estimate that anomalies of order 1-10 mGal are expected due to potentially varying density of surface and/or subsurface horizons. This accuracy is achievable with the latest GRAIL gravity models. The LRS surface backscattering power is indicative of surface and near sub-surface dielectric properties, which are sensitive to target density and roughness. We investigate the northwestern part of the Procellarum basin because it is the region with the strongest signal-to-noise ratios in gravity models within maria. To examine shallow subsurface structure, we map the surface received power by tracking the first return of radar echoes and compare it with gravity gradients, which are particularly sensitive to small-scale structures.

Geological Structures Mapping of Bukit Bunuh using 2-D Resistivity Imaging Method

NASA Astrophysics Data System (ADS)

Nur Amalina, M. K. A.; Nordiana, M. M.; Rahman, Nazrin; Saidin, Mokhtar; Masnan, S. S. K.

2018-04-01

The geological area of Bukit Bunuh is very complex due to the meteorite impact that has occurred millions years ago at Lenggong, Perak. The lithology of the study area consists of alluvium, tephra dust, and granitic rock. The geological contact, fault and fracture zone were found at the study area may indicate the geological process that undergoes at a place locally or regionally. These important features have led to the further research on 2-D resistivity imaging method (2-D RIM) to study the geological features. This method can provide the subsurface image that will delineate the geological structures. The surveys include three separate lines of different length which depend on the accessibility. The surveys were done by using Pole-Dipole array and 10 m of electrodes spacing. The objectives of this research are to determine the subsurface geological contact and to determine the existence of fault/fracture zones at the contact zone. The results from 2-D inversion profiles have successfully signified the types of geological structural such as fault, contact, and fractures. Hence, the results from 2-D RIM were used to draw the geological lineaments of Bukit Bunuh. The discontinuity of the lineaments may indicate the structures present.

A 3D visualization of spatial relationship between geological structure and groundwater chemical profile around Iwate volcano, Japan: based on the ARCGIS 3D Analyst

NASA Astrophysics Data System (ADS)

Shibahara, A.; Ohwada, M.; Itoh, J.; Kazahaya, K.; Tsukamoto, H.; Takahashi, M.; Morikawa, N.; Takahashi, H.; Yasuhara, M.; Inamura, A.; Oyama, Y.

2009-12-01

We established 3D geological and hydrological model around Iwate volcano to visualize 3D relationships between subsurface structure and groundwater profile. Iwate volcano is a typical polygenetic volcano located in NE Japan, and its body is composed of two stratovolcanoes which have experienced sector collapses several times. Because of this complex structure, groundwater flow around Iwate volcano is strongly restricted by subsurface construction. For example, Kazahaya and Yasuhara (1999) clarified that shallow groundwater in north and east flanks of Iwate volcano are recharged at the mountaintop, and these flow systems are restricted in north and east area because of the structure of younger volcanic body collapse. In addition, Ohwada et al. (2006) found that these shallow groundwater in north and east flanks have relatively high concentration of major chemical components and high 3He/4He ratios. In this study, we succeeded to visualize the spatial relationship between subsurface structure and chemical profile of shallow and deep groundwater system using 3D model on the GIS. In the study region, a number of geological and hydrological datasets, such as boring log data and groundwater chemical profile, were reported. All these paper data are digitized and converted to meshed data on the GIS, and plotted in the three dimensional space to visualize spatial distribution. We also inputted digital elevation model (DEM) around Iwate volcano issued by the Geographical Survey Institute of Japan, and digital geological maps issued by Geological Survey of Japan, AIST. All 3D models are converted into VRML format, and can be used as a versatile dataset on personal computer.

WISDOM, a polarimetric GPR for the shallow subsurface characterization

NASA Astrophysics Data System (ADS)

Ciarletti, V.; Plettemeier, D.; Hassen-Kodja, R.; Clifford, S. M.; Wisdom Team

2011-12-01

WISDOM (Water Ice and Subsurface Deposit Observations on Mars) is a polarimetric Ground Penetrating Radar (GPR) that has been selected to be part of the Pasteur payload onboard the Rover of the 2018 ExoMars mission. It will perform large-scale scientific investigations of the sub-surface of the landing site and provide precise information about the subsurface structure prior to drilling. WISDOM has been designed to provide accurate information on the sub-surface structure down to a depth in excess to 2 meters (commensurate to the drill capacities) with a vertical resolution of a several centimetres. It will give access to the geological structure, electromagnetic nature, and, possibly, to the hydrological state of the shallow subsurface by retrieving the layering and properties of the layers and buried reflectors. The data will also be used to determine the most promising locations to collect underground samples with the drilling system mounted on board the rover. Polarimetric measurements have been recently acquired on perfectly known targets as well as in natural environments. They demonstrated the ability to provide a better understanding of sub-surface structure and significantly reduce the ambiguity associated with identifying the location of off-nadir reflectors, relative to the rover path. This work describes the instrument and its operating modes with particular emphasis on its polarimetric capacities.

On the relative role of meridional convergence and downwelling motion during the heat buildup leading to El Niño events

NASA Astrophysics Data System (ADS)

Ballester, Joan; Bordoni, Simona; Petrova, Desislava; Rodó, Xavier

2015-04-01

Despite steady progress in the understanding of El Niño-Southern Oscillation (ENSO) in the past decades, questions remain on the exact mechanisms leading to the onset of El Niño (EN) events. Several authors have highlighted how the subsurface heat buildup in the western tropical Pacific and the recharged phase in equatorial heat content are intrinsic elements of ENSO variability, leading to those changes in zonal wind stress, sea surface temperature and thermocline tilt that characterize the growing and mature phases of EN. Here we use an ensemble of ocean and atmosphere assimilation products to identify the mechanisms contributing to the heat buildup that precedes EN events by about 18-24 months on average. Anomalous equatorward subsurface mass convergence due to meridional Sverdrup transport is found to be an important mechanism of thermocline deepening near and to the east of the dateline. In the warm pool, instead, surface horizontal convergence and downwelling motion have a leading role in subsurface warming, since equatorward mass convergence is weaker and counterbalanced by subsurface zonal divergence. The picture emerging from our results highlights the complexity of the three dimensional dynamic and thermodynamic structure of the tropical Pacific during the heat buildup leading to EN events.

PropBase Query Layer: a single portal to UK subsurface physical property databases

NASA Astrophysics Data System (ADS)

Kingdon, Andrew; Nayembil, Martin L.; Richardson, Anne E.; Smith, A. Graham

2013-04-01

Until recently, the delivery of geological information for industry and public was achieved by geological mapping. Now pervasively available computers mean that 3D geological models can deliver realistic representations of the geometric location of geological units, represented as shells or volumes. The next phase of this process is to populate these with physical properties data that describe subsurface heterogeneity and its associated uncertainty. Achieving this requires capture and serving of physical, hydrological and other property information from diverse sources to populate these models. The British Geological Survey (BGS) holds large volumes of subsurface property data, derived both from their own research data collection and also other, often commercially derived data sources. This can be voxelated to incorporate this data into the models to demonstrate property variation within the subsurface geometry. All property data held by BGS has for many years been stored in relational databases to ensure their long-term continuity. However these have, by necessity, complex structures; each database contains positional reference data and model information, and also metadata such as sample identification information and attributes that define the source and processing. Whilst this is critical to assessing these analyses, it also hugely complicates the understanding of variability of the property under assessment and requires multiple queries to study related datasets making extracting physical properties from these databases difficult. Therefore the PropBase Query Layer has been created to allow simplified aggregation and extraction of all related data and its presentation of complex data in simple, mostly denormalized, tables which combine information from multiple databases into a single system. The structure from each relational database is denormalized in a generalised structure, so that each dataset can be viewed together in a common format using a simple interface. Data are re-engineered to facilitate easy loading. The query layer structure comprises tables, procedures, functions, triggers, views and materialised views. The structure contains a main table PRB_DATA which contains all of the data with the following attribution: • a unique identifier • the data source • the unique identifier from the parent database for traceability • the 3D location • the property type • the property value • the units • necessary qualifiers • precision information and an audit trail Data sources, property type and units are constrained by dictionaries, a key component of the structure which defines what properties and inheritance hierarchies are to be coded and also guides the process as to what and how these are extracted from the structure. Data types served by the Query Layer include site investigation derived geotechnical data, hydrogeology datasets, regional geochemistry, geophysical logs as well as lithological and borehole metadata. The size and complexity of the data sets with multiple parent structures requires a technically robust approach to keep the layer synchronised. This is achieved through Oracle procedures written in PL/SQL containing the logic required to carry out the data manipulation (inserts, updates, deletes) to keep the layer synchronised with the underlying databases either as regular scheduled jobs (weekly, monthly etc) or invoked on demand. The PropBase Query Layer's implementation has enabled rapid data discovery, visualisation and interpretation of geological data with greater ease, simplifying the parametrisation of 3D model volumes and facilitating the study of intra-unit heterogeneity.

Generalized effective-mass theory of subsurface scanning tunneling microscopy: Application to cleaved quantum dots

NASA Astrophysics Data System (ADS)

Roy, M.; Maksym, P. A.; Bruls, D.; Offermans, P.; Koenraad, P. M.

2010-11-01

An effective-mass theory of subsurface scanning tunneling microscopy (STM) is developed. Subsurface structures such as quantum dots embedded into a semiconductor slab are considered. States localized around subsurface structures match on to a tail that decays into the vacuum above the surface. It is shown that the lateral variation in this tail may be found from a surface envelope function provided that the effects of the slab surfaces and the subsurface structure decouple approximately. The surface envelope function is given by a weighted integral of a bulk envelope function that satisfies boundary conditions appropriate to the slab. The weight function decays into the slab inversely with distance and this slow decay explains the subsurface sensitivity of STM. These results enable STM images to be computed simply and economically from the bulk envelope function. The method is used to compute wave-function images of cleaved quantum dots and the computed images agree very well with experiment.

Fibre optic confocal imaging (FOCI) for subsurface microscopy of the colon in vivo.

PubMed Central

Delaney, P M; King, R G; Lambert, J R; Harris, M R

1994-01-01

Fibre optic confocal imaging (FOCI) is a new type of microscopy which has been recently developed (Delaney et al. 1993). In contrast to conventional light microscopy, FOCI and other confocal techniques allow clear imaging of subsurface structures within translucent objects. However, unlike conventional confocal microscopes which are bulky (because of a need for accurate alignment of large components) FOCI allows the imaging end to be miniaturised and relatively mobile. FOCI is thus particularly suited for clear subsurface imaging of structures within living animals or subjects. The aim of the present study was to assess the suitability of using FOCI for imaging of subsurface structures within the colon, both in vitro (human and rat biopsies) and in vivo (in rats). Images were obtained in fluorescence mode (excitation 488 nm, detection above 515 nm) following topical application of fluorescein. By this technique the glandular structure of the colon was imaged. FOCI is thus suitable for subsurface imaging of the colon in vivo. Images Fig. 2 Fig. 3 PMID:8157487

Illuminating the Voluminous Subsurface Structures of Old Faithful Geyser, Yellowstone National Park

NASA Astrophysics Data System (ADS)

Hurwitz, Shaul; Shelly, David R.

2017-10-01

Old Faithful geyser in Yellowstone National Park has attracted scientific research for almost a century and a half. Temperature and pressure measurements and video recordings in the geyser's conduit led to proposals of many quantitative eruption models. Nevertheless, information on the processes that initiate the geyser's eruption in the subsurface remained limited. Two new studies, specifically Wu et al. (2017) and Ward and Lin (2017), take advantage of recent developments in seismic data acquisition technology and processing methods to illuminate subsurface structures. Using a dense array of three-component nodal geophones, these studies delineate subsurface structures on a scale larger than previously realized, which exert control on the spectacular eruptions of Old Faithful geyser.

Potential of Probing the Lunar Regolith using Rover-Mounted Ground Penetrating Radar: Moses Lake Dune Field Analog Study

NASA Technical Reports Server (NTRS)

Horz, F.; Heggy, E.; Fong, T.; Kring, D.; Deans, M.; Anglade, A.; Mahiouz, K.; Bualat, M.; Lee, P.; Bluethmann, W.

2009-01-01

Probing radars have been widely recognized by the science community to be an efficient tool to explore lunar subsurface providing a unique capability to address several scientific and operational issues. A wideband (200 to 1200 MHz) Ground Penetrating Radar (GPR) mounted on a surface rover can provide high vertical resolution and probing depth from few tens of centimeters to few tens of meters depending on the sounding frequency and the ground conductivity. This in term can provide a better understand regolith thickness, elemental iron concentration (including ilmenite), volatile presence, structural anomalies and fracturing. All those objectives are of important significance for understanding the local geology and potential sustainable resources for future landing sites in particular exploring the thickness, structural heterogeneity and potential volatiles presence in the lunar regolith. While the operation and data collection of GPR is a straightforward case for most terrestrial surveys, it is a challenging task for remote planetary study especially on robotic platforms due to the complexity of remote operation in rough terrains and the data collection constrains imposed by the mechanical motion of the rover and limitation in data transfer. Nevertheless, Rover mounted GPR can be of great support to perform systematic subsurface surveys for a given landing site as it can provide scientific and operational support in exploring subsurface resources and sample collections which can increase the efficiency of the EVA activities for potential human crews as part of the NASA Constellation Program. In this study we attempt to explore the operational challenges and their impact on the EVA scientific return for operating a rover mounted GPR in support of potential human activity on the moon. In this first field study, we mainly focused on the ability of GPR to support subsurface sample collection and explore shallow subsurface volatiles.

Solfatara volcano subsurface imaging: two different approaches to process and interpret multi-variate data sets

NASA Astrophysics Data System (ADS)

Bernardinetti, Stefano; Bruno, Pier Paolo; Lavoué, François; Gresse, Marceau; Vandemeulebrouck, Jean; Revil, André

2017-04-01

The need to reduce model uncertainty and produce a more reliable geophysical imaging and interpretations is nowadays a fundamental task required to geophysics techniques applied in complex environments such as Solfatara Volcano. The use of independent geophysical methods allows to obtain many information on the subsurface due to the different sensitivities of the data towards parameters such as compressional and shearing wave velocities, bulk electrical conductivity, or density. The joint processing of these multiple physical properties can lead to a very detailed characterization of the subsurface and therefore enhance our imaging and our interpretation. In this work, we develop two different processing approaches based on reflection seismology and seismic P-wave tomography on one hand, and electrical data acquired over the same line, on the other hand. From these data, we obtain an image-guided electrical resistivity tomography and a post processing integration of tomographic results. The image-guided electrical resistivity tomography is obtained by regularizing the inversion of the electrical data with structural constraints extracted from a migrated seismic section using image processing tools. This approach enables to focus the reconstruction of electrical resistivity anomalies along the features visible in the seismic section, and acts as a guide for interpretation in terms of subsurface structures and processes. To integrate co-registrated P-wave velocity and electrical resistivity values, we apply a data mining tool, the k-means algorithm, to individuate relationships between the two set of variables. This algorithm permits to individuate different clusters with the objective to minimize the sum of squared Euclidean distances within each cluster and maximize it between clusters for the multivariate data set. We obtain a partitioning of the multivariate data set in a finite number of well-correlated clusters, representative of the optimum clustering of our geophysical variables (P-wave velocities and electrical resistivities). The result is an integrated tomography that shows a finite number of homogeneous geophysical facies, and therefore permits to highlight the main geological features of the subsurface.

Detailed 3D Geophysical Model of the Shallow Subsurface (Zancara River Basin, Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Carbonell, R.; Marzán, I.; Martí, D.; Lobo, A.; Jean, K.; Alvarez-Marrón, J.

2016-12-01

Detailed knowledge of the structure and lithologies of the shallow subsurface is required when designing and building singular geological storage facilities this is the case of the study area in Villar de Cañas (Cuenca, Central Spain). In which an extensive multidisciplinary data acquisition program has been carried out. This include studies on: geology, hydrology, geochemistry, geophysics, borehole logging, etc. Because of this data infrastructure, it can be considered a subsurface imaging laboratory to test and validate indirect underground characterization approaches. The field area is located in a Miocene syncline within the Záncara River Basin (Cuenca, Spain). The sedimentary sequence consists in a transition from shales to massive gypsums, and underlying gravels. The stratigraphic succession features a complex internal structure, diffused lithological boundaries and relatively large variability of properties within the same lithology, these makes direct geological interpretation very difficult and requires of the integration of all the measured physical properties. The ERT survey, the seismic tomography data and the logs have been used jointly to build a 3-D multi-parameter model of the subsurface in a surface of 500x500 m. The Vp model (a 10x20x5 m grid) is able to map the high velocities of the massive gypsum, however it was neither able to map the details of the shale-gypsm transition (low velocity contrast) nor to differentiate the outcropping altered gypsum from the weathered shales. The integration of the electrical resistivity and the log data by means of a supervised statistical tools (Linear Discriminant Analysis, LDA) resulted in a new 3D multiparametric subsurface model. This new model integrates the different data sets resolving the uncertainties characteristic of the models obtained independently by the different techniques separately. Furthermore, this test seismic dataset has been used to test FWI approaches in order to study their capacities. (Research supports: CGL2014-56548-P, 2009-SGR-1595, CGL2013-47412-C2-1-P).

Geoelectrical image of the subsurface for CO2 geological storage in the Changhua site, Taiwan

NASA Astrophysics Data System (ADS)

Chiang, C. W.; Chiao, C. H.; Yang, M. W.; Yu, C. W.; Yang, C. H.; Chen, C. C.

2016-12-01

Global warming has recently become an important worldwide issue. Reduction of carbon dioxide (CO2) emission is recommended by Intergovernmental Panel on Climate Change, which geological storage is one of possible way to reduce the CO2 issue. The Taichung Power Plant is a coal-fired power plant operated by the Taiwan Power Company in Taichung, Taiwan, which is the largest coal-fired power station in the world. The power plant emits approximately 40 million tons annually which is also the world's largest CO2 emitter. Geophysical techniques are presented as the most useful tool to characterize the reservoir. The electrical resistivity tool was carried out applying audio-magnetotelluric (AMT) method, which could provide the depth resolution for evaluating the subsurface. A first survey of 20 AMT soundings was acquired to study the viability of the method to characterize the subsurface. Stations were deployed at approximately 500 m intervals and the data were recorded in the frequency range of 104-100 Hz. The dimensionality analysis proved the validity of the 1-D or 2-D assumption. The visualized model shows a layered electrical resistivity structure from shallow to depth of 3000 m. The preliminary result corresponds to seismic reflection and geological investigations that suggests a simple geological structure without complex geological processes in the area. It could be a suitable site for geological storage.

Pattern-Based Inverse Modeling for Characterization of Subsurface Flow Models with Complex Geologic Heterogeneity

NASA Astrophysics Data System (ADS)

Golmohammadi, A.; Jafarpour, B.; M Khaninezhad, M. R.

2017-12-01

Calibration of heterogeneous subsurface flow models leads to ill-posed nonlinear inverse problems, where too many unknown parameters are estimated from limited response measurements. When the underlying parameters form complex (non-Gaussian) structured spatial connectivity patterns, classical variogram-based geostatistical techniques cannot describe the underlying connectivity patterns. Modern pattern-based geostatistical methods that incorporate higher-order spatial statistics are more suitable for describing such complex spatial patterns. Moreover, when the underlying unknown parameters are discrete (geologic facies distribution), conventional model calibration techniques that are designed for continuous parameters cannot be applied directly. In this paper, we introduce a novel pattern-based model calibration method to reconstruct discrete and spatially complex facies distributions from dynamic flow response data. To reproduce complex connectivity patterns during model calibration, we impose a feasibility constraint to ensure that the solution follows the expected higher-order spatial statistics. For model calibration, we adopt a regularized least-squares formulation, involving data mismatch, pattern connectivity, and feasibility constraint terms. Using an alternating directions optimization algorithm, the regularized objective function is divided into a continuous model calibration problem, followed by mapping the solution onto the feasible set. The feasibility constraint to honor the expected spatial statistics is implemented using a supervised machine learning algorithm. The two steps of the model calibration formulation are repeated until the convergence criterion is met. Several numerical examples are used to evaluate the performance of the developed method.

Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

NASA Astrophysics Data System (ADS)

Hare, Danielle K.; Boutt, David F.; Clement, William P.; Hatch, Christine E.; Davenport, Glorianna; Hackman, Alex

2017-11-01

Peatland environments provide important ecosystem services including water and carbon storage, nutrient processing and retention, and wildlife habitat. However, these systems and the services they provide have been degraded through historical anthropogenic agricultural conversion and dewatering practices. Effective wetland restoration requires incorporating site hydrology and understanding groundwater discharge spatial patterns. Groundwater discharge maintains wetland ecosystems by providing relatively stable hydrologic conditions, nutrient inputs, and thermal buffering important for ecological structure and function; however, a comprehensive site-specific evaluation is rarely feasible for such resource-constrained projects. An improved process-based understanding of groundwater discharge in peatlands may help guide ecological restoration design without the need for invasive methodologies and detailed site-specific investigation. Here we examine a kettle-hole peatland in southeast Massachusetts historically modified for commercial cranberry farming. During the time of our investigation, a large process-based ecological restoration project was in the assessment and design phases. To gain insight into the drivers of site hydrology, we evaluated the spatial patterning of groundwater discharge and the subsurface structure of the peatland complex using heat-tracing methods and ground-penetrating radar. Our results illustrate that two groundwater discharge processes contribute to the peatland hydrologic system: diffuse lower-flux marginal matrix seepage and discrete higher-flux preferential-flow-path seepage. Both types of groundwater discharge develop through interactions with subsurface peatland basin structure, often where the basin slope is at a high angle to the regional groundwater gradient. These field observations indicate strong correlation between subsurface structures and surficial groundwater discharge. Understanding these general patterns may allow resource managers to more efficiently predict and locate groundwater seepage, confirm these using remote sensing technologies, and incorporate this information into restoration design for these critical ecosystems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Glenn Edward; Bao, J; Huang, M

Hyporheic exchange is a critical mechanism shaping hydrological and biogeochemical processes along a river corridor. Recent studies on quantifying the hyporheic exchange were mostly limited to local scales due to field inaccessibility, computational demand, and complexity of geomorphology and subsurface geology. Surface flow conditions and subsurface physical properties are well known factors on modulating the hyporheic exchange, but quantitative understanding of their impacts on the strength and direction of hyporheic exchanges at reach scales is absent. In this study, a high resolution computational fluid dynamics (CFD) model that couples surface and subsurface flow and transport is employed to simulate hyporheicmore » exchanges in a 7-km long reach along the main-stem of the Columbia River. Assuming that the hyporheic exchange does not affect surface water flow conditions due to its negligible magnitude compared to the volume and velocity of river water, we developed a one-way coupled surface and subsurface water flow model using the commercial CFD software STAR-CCM+. The model integrates the Reynolds-averaged Navier-Stokes (RANS) equation solver with a realizable κ-ε two-layer turbulence model, a two-layer all y + wall treatment, and the volume of fluid (VOF) method, and is used to simulate hyporheic exchanges by tracking the free water-air interface as well as flow in the river and the subsurface porous media. The model is validated against measurements from acoustic Doppler current profiler (ADCP) in the stream water and hyporheic fluxes derived from a set of temperature profilers installed across the riverbed. The validated model is then employed to systematically investigate how hyporheic exchanges are influenced by surface water fluid dynamics strongly regulated by upstream dam operations, as well as subsurface structures (e.g. thickness of riverbed and subsurface formation layers) and hydrogeological properties (e.g. permeability). The results suggest that the thickness of riverbed alluvium layer is the dominant factor for reach-scale hyporheic exchanges, followed by the alluvium permeability, the depth of the underlying impermeable layer, and the assumption of hydrostatic pressure.« less

Upper crustal structures beneath Yogyakarta imaged by ambient seismic noise tomography

NASA Astrophysics Data System (ADS)

Zulfakriza, Saygin, E.; Cummins, P.; Widiyantoro, S.; Nugraha, Andri Dian

2013-09-01

Delineating the upper crustal structures beneath Yogyakarta is necessary for understanding its tectonic setting. The presence of Mt. Merapi, fault line and the alluvial deposits contributes to the complex geology of Yogyakarta. Recently, ambient seismic noise tomography can be used to image the subsurface structure. The cross correlations of ambient seismic noise of pair stations were applied to extract the Green's function. The total of 27 stations from 134 seismic stations available in MERapi Amphibious EXperiment (MERAMEX) covering Yogyakarta region were selected to conduct cross correlation. More than 500 Rayleigh waves of Green's functions could be extracted by cross-correlating available the station pairs of short-period and broad-band seismometers. The group velocities were obtained by filtering the extracted Green's function between 0.5 and 20 s. 2-D inversion was applied to the retrieved travel times. Features in the derived tomographic images correlate with the surface geology of Yogyakarta. The Merapi active volcanoes and alluvial deposit in Yogyakarta are clearly described by lower group velocities. The high velocity anomaly contrasts which are visible in the images obtained from the period range between 1 and 5 s, correspond to subsurface imprints of fault that could be the Opak Fault.

Theoretical aspects of studies of high coverage oxidation of the Cu(100) surface using low energy positrons

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Maddox, W. B.; Reed, J. A.

2011-03-01

The study of adsorption of oxygen on transition metal surface is important for the understanding of oxidation, heterogeneous catalysis, and metal corrosion. The structures formed on transition metal surfaces vary from simple adlayers of chemisorbed oxygen to more complex structures which results from diffusion of oxygen into the sub-surface regions. In this work we present the results of an ab-initio investigation of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the Cu(100) missing row reconstructed surface under conditions of high oxygen coverage. Calculations are performed for various surface and subsurface oxygen coverages ranging from 0.50 to 1.50 monolayers. Calculations are also performed for the on-surface adsorption of oxygen on the unreconstructed Cu(001) surface for coverages up to one monolayer to use for comparison. Estimates of the positron binding energy, positron work function, and annihilation characteristics reveal their sensitivity to atomic structure of the topmost layers of the surface and charge transfer. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy.

Niobrara Discrete Fracture Network: From Outcrop Surveys to Subsurface Reservoir Models

NASA Astrophysics Data System (ADS)

Grechishnikova, Alena

Heterogeneity of an unconventional reservoir is one of the main factors affecting production. Well performance depends on the size and efficiency of the interconnected fracture "plumbing system", as influenced by multistage hydraulic fracturing. A complex, interconnected natural fracture network can significantly increase the size of stimulated reservoir volume, provide additional surface area contact and enhance permeability. In 2013 the Reservoir Characterization Project (RCP) at the Colorado School of Mines began Phase XV to study Niobrara shale reservoir management. Anadarko Petroleum Corporation and RCP jointly acquired time-lapse multicomponent seismic data in Wattenberg Field, Denver Basin. Anadarko also provided RCP with a regional 3D seismic survey and a rich well dataset. The purpose of this study is to characterize the natural fracture patterns occurring in the unconventional Niobrara reservoir and to determine the drivers that influenced fracture trends and distributions. The findings are integrated into a reservoir model though DFN (Discrete Fracture Network) for further prediction of reservoir performance using reservoir simulations. Aiming to better understand the complexity of the natural fracture system I began my fracture analysis work at an active mine site that provides a Niobrara exposure. Access to a "fresh" outcrop surface created a perfect natural laboratory. Ground-based LIDAR and photogrammetry facilitated construction of a geological model and a DFN model for the mine site. The work was carried into subsurface where the information gained served to improve reservoir characterization at a sub-seismic scale and can be used in well planning. I then embarked on a challenging yet essential task of outcrop-to-subsurface data calibration and application to RCP's Wattenberg Field study site. In this research the surface data was proven to be valid for comparative use in the subsurface. The subsurface fracture information was derived from image logs run within the horizontal wellbores and augmented with microseismic data. Limitations of these datasets included the potential to induce biased interpretations; but the data collected during the outcrop study aided in removing the bias. All four fracture sets observed at the quarry were also interpreted in the subsurface; however there was a limitation on statistical validity for one of the four sets due to a low frequency of observed occurrence potentially caused by wellbore orientation. Microseismic data was used for identification of one of the reactivated natural fracture sets. An interesting phenomenon observed in the microseismic data trends was the low frequency of event occurrence within dense populations of open natural fracture swarms suggesting that zones of higher natural fracture intensities are capable of absorbing and transmitting energy resulting in lower levels of microseismicity. Thus currently open natural fractures could be challenging to detect using microseismic. Through this study I identified a significant variability in fracture intensity at a localized scale due to lithological composition and structural features. The complex faulting styles observed at the outcrop were utilized as an analog and verified by horizontal well log data and seismic volume interpretations creating a high resolution structural model for the subsurface. A lithofacies model was developed based on the well log, core, and seismic inversion analysis. These models combined served to accurately distribute fracture intensity information within the geological model for further use in DFN. As a product of this study, a workflow was developed to aid in fracture network model creation allowing for more intelligent decisions to be made during well planning and completion optimization aiming to improve recovery. A high resolution integrated discrete fracture network model serves to advance dynamic reservoir characterization in the subsurface at a sub-seismic scale resulting in improved reservoir characterization.

Application of model abstraction techniques to simulate transport in soils

USDA-ARS?s Scientific Manuscript database

Successful understanding and modeling of contaminant transport in soils is the precondition of risk-informed predictions of the subsurface contaminant transport. Exceedingly complex models of subsurface contaminant transport are often inefficient. Model abstraction is the methodology for reducing th...

Adaptive Wavelet Modeling of Geophysical Data

NASA Astrophysics Data System (ADS)

Plattner, A.; Maurer, H.; Dahmen, W.; Vorloeper, J.

2009-12-01

Despite the ever-increasing power of modern computers, realistic modeling of complex three-dimensional Earth models is still a challenging task and requires substantial computing resources. The overwhelming majority of current geophysical modeling approaches includes either finite difference or non-adaptive finite element algorithms, and variants thereof. These numerical methods usually require the subsurface to be discretized with a fine mesh to accurately capture the behavior of the physical fields. However, this may result in excessive memory consumption and computing times. A common feature of most of these algorithms is that the modeled data discretizations are independent of the model complexity, which may be wasteful when there are only minor to moderate spatial variations in the subsurface parameters. Recent developments in the theory of adaptive numerical solvers have the potential to overcome this problem. Here, we consider an adaptive wavelet based approach that is applicable to a large scope of problems, also including nonlinear problems. To the best of our knowledge such algorithms have not yet been applied in geophysics. Adaptive wavelet algorithms offer several attractive features: (i) for a given subsurface model, they allow the forward modeling domain to be discretized with a quasi minimal number of degrees of freedom, (ii) sparsity of the associated system matrices is guaranteed, which makes the algorithm memory efficient, and (iii) the modeling accuracy scales linearly with computing time. We have implemented the adaptive wavelet algorithm for solving three-dimensional geoelectric problems. To test its performance, numerical experiments were conducted with a series of conductivity models exhibiting varying degrees of structural complexity. Results were compared with a non-adaptive finite element algorithm, which incorporates an unstructured mesh to best fit subsurface boundaries. Such algorithms represent the current state-of-the-art in geoelectrical modeling. An analysis of the numerical accuracy as a function of the number of degrees of freedom revealed that the adaptive wavelet algorithm outperforms the finite element solver for simple and moderately complex models, whereas the results become comparable for models with spatially highly variable electrical conductivities. The linear dependency of the modeling error and the computing time proved to be model-independent. This feature will allow very efficient computations using large-scale models as soon as our experimental code is optimized in terms of its implementation.

Imaging of Subsurface Corrosion Using Gradient-Field Pulsed Eddy Current Probes with Uniform Field Excitation

PubMed Central

Ren, Shuting; Yan, Bei; Zainal Abidin, Ilham Mukriz; Wang, Yi

2017-01-01

A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size. PMID:28758985

Imaging of Subsurface Corrosion Using Gradient-Field Pulsed Eddy Current Probes with Uniform Field Excitation.

PubMed

Li, Yong; Ren, Shuting; Yan, Bei; Zainal Abidin, Ilham Mukriz; Wang, Yi

2017-07-31

A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size.

Deformation and kinematic evolution of the subsurface structures: Zagros foreland fold-and-thrust belt, northern Dezful Embayment, Iran

NASA Astrophysics Data System (ADS)

Sarkarinejad, Khalil; Pash, Raana Razavi; Motamedi, Hossein; Yazdani, Mohammad

2018-06-01

The Dezful Embayment is located in the foreland part of the Zagros fold-and-thrust belt. Structural style of folding and thrusting vary in the Dezful Embayment. In this study, balanced cross sections and subsurface data including 2D seismic profiles and wells data decoded structural style of the subsurface structures in the northern Dezful Embayment. Presence of the multiple décollement horizons is the main controlling factor of the structural style in this area. The subsurface anticlines have been formed between two main décollement horizons, which include the Miocene Gachsaran Formation as upper decollement and Permian Dashtak evaporites and Lower Cretaceous Garau shales as the middle décollement horizons. Geometry of the subsurface anticlines differs much vertically and horizontally. Growth strata indicate folding is started in Middle Miocene time in this region. Anticlines formed as open, wide and disharmonic structures. Active processes in the evolution of anticlines are limb rotation and hinge migration, which was resulted in increase of inhomogeneous shortening rate. More shortening rate indicates more structural relief in anticlines. These anticlines are formed as a detachment folds in initiation and then during their evolution converted to fault propagation fold and fault-bend fold. Final geometric shape of these anticlines depends on the geometry of thrusts propagation that formed in the forelimb.

Three-dimensional geoelectric modelling with optimal work/accuracy rate using an adaptive wavelet algorithm

NASA Astrophysics Data System (ADS)

Plattner, A.; Maurer, H. R.; Vorloeper, J.; Dahmen, W.

2010-08-01

Despite the ever-increasing power of modern computers, realistic modelling of complex 3-D earth models is still a challenging task and requires substantial computing resources. The overwhelming majority of current geophysical modelling approaches includes either finite difference or non-adaptive finite element algorithms and variants thereof. These numerical methods usually require the subsurface to be discretized with a fine mesh to accurately capture the behaviour of the physical fields. However, this may result in excessive memory consumption and computing times. A common feature of most of these algorithms is that the modelled data discretizations are independent of the model complexity, which may be wasteful when there are only minor to moderate spatial variations in the subsurface parameters. Recent developments in the theory of adaptive numerical solvers have the potential to overcome this problem. Here, we consider an adaptive wavelet-based approach that is applicable to a large range of problems, also including nonlinear problems. In comparison with earlier applications of adaptive solvers to geophysical problems we employ here a new adaptive scheme whose core ingredients arose from a rigorous analysis of the overall asymptotically optimal computational complexity, including in particular, an optimal work/accuracy rate. Our adaptive wavelet algorithm offers several attractive features: (i) for a given subsurface model, it allows the forward modelling domain to be discretized with a quasi minimal number of degrees of freedom, (ii) sparsity of the associated system matrices is guaranteed, which makes the algorithm memory efficient and (iii) the modelling accuracy scales linearly with computing time. We have implemented the adaptive wavelet algorithm for solving 3-D geoelectric problems. To test its performance, numerical experiments were conducted with a series of conductivity models exhibiting varying degrees of structural complexity. Results were compared with a non-adaptive finite element algorithm, which incorporates an unstructured mesh to best-fitting subsurface boundaries. Such algorithms represent the current state-of-the-art in geoelectric modelling. An analysis of the numerical accuracy as a function of the number of degrees of freedom revealed that the adaptive wavelet algorithm outperforms the finite element solver for simple and moderately complex models, whereas the results become comparable for models with high spatial variability of electrical conductivities. The linear dependence of the modelling error and the computing time proved to be model-independent. This feature will allow very efficient computations using large-scale models as soon as our experimental code is optimized in terms of its implementation.

Influence of cutting parameters on the depth of subsurface deformed layer in nano-cutting process of single crystal copper.

PubMed

Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Su, Hao; Wang, Zhiguo; Xie, Wenkun

2015-12-01

Large-scale molecular dynamics simulation is performed to study the nano-cutting process of single crystal copper realized by single-point diamond cutting tool in this paper. The centro-symmetry parameter is adopted to characterize the subsurface deformed layers and the distribution and evolution of the subsurface defect structures. Three-dimensional visualization and measurement technology are used to measure the depth of the subsurface deformed layers. The influence of cutting speed, cutting depth, cutting direction, and crystallographic orientation on the depth of subsurface deformed layers is systematically investigated. The results show that a lot of defect structures are formed in the subsurface of workpiece during nano-cutting process, for instance, stair-rod dislocations, stacking fault tetrahedron, atomic clusters, vacancy defects, point defects. In the process of nano-cutting, the depth of subsurface deformed layers increases with the cutting distance at the beginning, then decreases at stable cutting process, and basically remains unchanged when the cutting distance reaches up to 24 nm. The depth of subsurface deformed layers decreases with the increase in cutting speed between 50 and 300 m/s. The depth of subsurface deformed layer increases with cutting depth, proportionally, and basically remains unchanged when the cutting depth reaches over 6 nm.

Geophysics applications in critical zone science: emerging topics

USDA-ARS?s Scientific Manuscript database

Geophysical studies have resulted in remarkable advances in characterization of critical zone. The geophysics applications uncover the relationships between structure and function in subsurface as they seek to define subsurface structural units with individual properties of retention and trans...

Microbial populations in contaminant plumes

USGS Publications Warehouse

Haack, S.K.; Bekins, B.A.

2000-01-01

Efficient biodegradation of subsurface contaminants requires two elements: (1) microbial populations with the necessary degradative capabilities, and (2) favorable subsurface geochemical and hydrological conditions. Practical constraints on experimental design and interpretation in both the hydrogeological and microbiological sciences have resulted in limited knowledge of the interaction between hydrogeological and microbiological features of subsurface environments. These practical constraints include: (1) inconsistencies between the scales of investigation in the hydrogeological and microbiological sciences, and (2) practical limitations on the ability to accurately define microbial populations in environmental samples. However, advances in application of small-scale sampling methods and interdisciplinary approaches to site investigations are beginning to significantly improve understanding of hydrogeological and microbiological interactions. Likewise, culture-based and molecular analyses of microbial populations in subsurface contaminant plumes have revealed significant adaptation of microbial populations to plume environmental conditions. Results of recent studies suggest that variability in subsurface geochemical and hydrological conditions significantly influences subsurface microbial-community structure. Combined investigations of site conditions and microbial-community structure provide the knowledge needed to understand interactions between subsurface microbial populations, plume geochemistry, and contaminant biodegradation.

Integration of Electrical Resistivity and Seismic Refraction using Combine Inversion for Detecting Material Deposits of Impact Crater at Bukit Bunuh, Lenggong, Perak

NASA Astrophysics Data System (ADS)

Yusoh, R.; Saad, R.; Saidin, M.; Muhammad, S. B.; Anda, S. T.

2018-04-01

Both electrical resistivity and seismic refraction profiling has become a common method in pre-investigations for visualizing subsurface structure. The encouragement to use these methods is that combined of both methods can decrease the obscure inherent to the distinctive use of these methods. Both method have their individual software packages for data inversion, but potential to combine certain geophysical methods are restricted; however, the research algorithms that have this functionality was exists and are evaluated personally. The interpretation of subsurface were improve by combining inversion data from both method by influence each other models using closure coupling; thus, by implementing both methods to support each other which could improve the subsurface interpretation. These methods were applied on a field dataset from a pre-investigation for archeology in finding the material deposits of impact crater. There were no major changes in the inverted model by combining data inversion for this archetype which probably due to complex geology. The combine data analysis shows the deposit material start from ground surface to 20 meter depth which the class separation clearly separate the deposit material.

Anisotropy of Single-Crystal Silicon in Nanometric Cutting.

PubMed

Wang, Zhiguo; Chen, Jiaxuan; Wang, Guilian; Bai, Qingshun; Liang, Yingchun

2017-12-01

The anisotropy exhibited by single-crystal silicon in nanometric cutting is very significant. In order to profoundly understand the effect of crystal anisotropy on cutting behaviors, a large-scale molecular dynamics model was conducted to simulate the nanometric cutting of single-crystal silicon in the (100)[0-10], (100)[0-1-1], (110)[-110], (110)[00-1], (111)[-101], and (111)[-12-1] crystal directions in this study. The simulation results show the variations of different degrees in chip, subsurface damage, cutting force, and friction coefficient with changes in crystal plane and crystal direction. Shear deformation is the formation mechanism of subsurface damage, and the direction and complexity it forms are the primary causes that result in the anisotropy of subsurface damage. Structurally, chips could be classified into completely amorphous ones and incompletely amorphous ones containing a few crystallites. The formation mechanism of the former is high-pressure phase transformation, while the latter is obtained under the combined action of high-pressure phase transformation and cleavage. Based on an analysis of the material removal mode, it can be found that compared with the other crystal direction on the same crystal plane, the (100)[0-10], (110)[-110], and (111)[-101] directions are more suitable for ductile cutting.

A Channel Network Evolution Model with Subsurface Saturation Mechanism and Analysis of the Chaotic Behavior of the Model

DTIC Science & Technology

1990-09-01

between basin shapes and hydrologic responses is fundamental for the purpose of hydrologic predictions , especially in ungaged basins. Another goal is...47] studied this model and showed analitically how very small differences in the c field generated completely different leaf vein network structures... predictability impossible. Complexity is by no means a requirement in order for a system to exhibit SIC. A system as simple as the logistic equation x,,,,=ax,,(l

Complex landslides in the Trans-Mexican Volcanic Belt - a case study in the State of Veracruz

NASA Astrophysics Data System (ADS)

Wilde, M.; Terhorst, B.; Schwindt, D.; Rodriguez Elizarrarás, S. R.; Morales Barrera, W. V.; Bücker, M.; Flores Orozco, A.; García García, E.; Pita de la Paz, C.

2017-12-01

The State of Veracruz (Mexico) is a region which is highly affected by landslides, therefore detailed studies on triggering factors and process dynamics of landslides are required. Profound insights are essential for further hazard assessments and compilation of susceptibility maps. Exemplary landslide sites were investigated in order to determine characteristic features of specific regions. In the Chiconquiaco Mountain Range numerous damaging landslide events occurred in the year of 2013 and our case study corresponds to a deep-seated landslide originating from this slide-intensive year. The main scientific aspects are placed on the reconstruction of the landslides geometry and its process dynamics. Therefore, surface and subsurface analysis form the base of a multimethodological approach. In order to perform surface analysis, aerial photographs were collected by an unmanned aerial vehicle (UAV) aiming at the generation of a 3D model with the Structure from Motion (SfM) work routine. Ground control points (GCP) were used to ensure the geometric accuracy of the model. The obtained DEM of the 2013 slide mass as well as an elevation model representing the topographic situation before the event (year 2011) were used to detect surface changes. The data enabled determination of the most affected areas as well as areas characterized by secondary movements. Furthermore, the volume of the slide mass could be calculated. Geophysical methods, as electrical resistivity tomography (ERT) as well as seismic refraction tomography (SRT), were applied for subsurface analysis. Differences in subsurface composition, respectively density, allowed for separation of the slide mass and the underlying unit. Most relevant for our studies is the detection of an earlier landslide leading to the assumption that the 2013 landslide event corresponds to a reactivation process. This multimethodological approach enables a far-reaching visualization of complex landslides and strongly supports the reconstruction of interior structures and process dynamics.

Nematoda from the terrestrial deep subsurface of South Africa.

PubMed

Borgonie, G; García-Moyano, A; Litthauer, D; Bert, W; Bester, A; van Heerden, E; Möller, C; Erasmus, M; Onstott, T C

2011-06-02

Since its discovery over two decades ago, the deep subsurface biosphere has been considered to be the realm of single-cell organisms, extending over three kilometres into the Earth's crust and comprising a significant fraction of the global biosphere. The constraints of temperature, energy, dioxygen and space seemed to preclude the possibility of more-complex, multicellular organisms from surviving at these depths. Here we report species of the phylum Nematoda that have been detected in or recovered from 0.9-3.6-kilometre-deep fracture water in the deep mines of South Africa but have not been detected in the mining water. These subsurface nematodes, including a new species, Halicephalobus mephisto, tolerate high temperature, reproduce asexually and preferentially feed upon subsurface bacteria. Carbon-14 data indicate that the fracture water in which the nematodes reside is 3,000-12,000-year-old palaeometeoric water. Our data suggest that nematodes should be found in other deep hypoxic settings where temperature permits, and that they may control the microbial population density by grazing on fracture surface biofilm patches. Our results expand the known metazoan biosphere and demonstrate that deep ecosystems are more complex than previously accepted. The discovery of multicellular life in the deep subsurface of the Earth also has important implications for the search for subsurface life on other planets in our Solar System.

Lunar and Martian Sub-surface Habitat Structure Technology Development and Application

NASA Technical Reports Server (NTRS)

Boston, Penelope J.; Strong, Janet D.

2005-01-01

NASA's human exploration initiative poses great opportunity and great risk for manned missions to the Moon and Mars. Subsidace structures such as caves and lava tubes offer readily available and existing in-situ habitat options. Sub-surface dwellings can provide complete radiation, micro-meteorite and exhaust plume shielding and a moderate and constant temperature environment; they are, therefore, excellent pre-existing habitat risk mitigation elements. Technical challenges to subsurface habitat structure development include surface penetration (digging and mining equipment), environmental pressurization, and psychological environment enhancement requirements. Lunar and Martian environments and elements have many beneficial similarities. This will allow for lunar testing and design development of subsurface habitat structures for Martian application; however, significant differences between lunar and Martian environments and resource elements will mandate unique application development. Mars is NASA's ultimate exploration goal and is known to have many very large lava tubes. Other cave types are plausible. The Moon has unroofed rilles and lava tubes, but further research will, in the near future, define the extent of Lunar and Martian differences and similarities. This paper will discuss Lunar and Martian subsurface habitation technology development challenges and opportunities.

Geophysical characterization of the role of fault and fracture systems for recharging groundwater aquifers from surface water of Lake Nasser

NASA Astrophysics Data System (ADS)

Mansour, Khamis; Omar, Khaled; Ali, Kamal; Abdel Zaher, Mohamed

2018-06-01

The role of the fracture system is important for enhancing the recharge or discharge of fluids in the subsurface reservoir. The Lake Nasser is consider one of the largest artificial lakes all over the world and contains huge bulk of storage water. In this study, the influence of fracture zones on subsurface fluid flow in groundwater reservoirs is investigated using geophysical techniques including seismicity, geoelectric and gravity data. These data have been utilized for exploring structural structure in south west Lake Nasser, and subsurface discontinuities (joints or faults) notwithstanding its related fracture systems. Seismicity investigation gave us the comprehension of the dynamic geological structure sets and proposing the main recharging paths for the Nubian aquifer from Lake Nasser surface water. Processing and modelling of aerogravity data show that the greater thickness of sedimentary cover (700 m) is located eastward and northward while basement outcrops occur at Umm Shaghir and Al Asr areas. Sixty-nine vertical electrical soundings (VES's) were used to delineate the subsurface geoelectric layers along eight profiles that help to realize the subsurface geological structure behind the hydrogeological conditions of the studied area.

Studies Based on Lunar Global Subsurface Radar Sounding Data Obtained by SELENE (Kaguya)

NASA Astrophysics Data System (ADS)

Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Haruyama, J.; Miyamoto, H.; Nishibori, T.; Tsuchiya, F.; Ohtake, M.

2018-04-01

Several studies based on lunar global subsurface radar sounding data obtained by SELENE/LRS will be reviewed. From the subsurface structures of the buried regolith layers, we can discuss the evolution of tectonic and volcanic processes in the maria.

Anatomy of terminal moraine segments and implied lake stability on Ngozumpa Glacier, Nepal, from electrical resistivity tomography (ERT).

PubMed

Thompson, Sarah S; Kulessa, Bernd; Benn, Douglas I; Mertes, Jordan R

2017-04-20

Moraine-dammed lakes at debris-covered glaciers are becoming increasingly common and pose significant outburst flood hazards if the dam is breached. While moraine subsurface structure and internal processes are likely to influence dam stability, only few sites have so far been investigated. We conducted electrical resistivity tomography (ERT) surveys at two sites on the terminal moraine complex of the Ngozumpa Glacier, Nepal, to aid assessment of future terminus stability. The resistivity signature of glacier ice at the site (100-15 kΩ m) is more consistent with values measured from cold glacier ice and while this may be feasible, uncertainties in the data inversion introduce ambiguity to this thermal interpretation. However, the ERT data does provide a significant improvement to our knowledge of the subsurface characteristics at these sites, clearly showing the presence (or absence) of glacier ice. Our interpretation is that of a highly complex latero-terminal moraine, resulting from interaction between previous glacier advance, recession and outburst flooding. If the base-level Spillway Lake continues to expand to a fully formed moraine-dammed glacial lake, the degradation of the ice core could have implications for glacial lake outburst risk.

Anatomy of terminal moraine segments and implied lake stability on Ngozumpa Glacier, Nepal, from electrical resistivity tomography (ERT)

NASA Astrophysics Data System (ADS)

Thompson, Sarah S.; Kulessa, Bernd; Benn, Douglas I.; Mertes, Jordan R.

2017-04-01

Moraine-dammed lakes at debris-covered glaciers are becoming increasingly common and pose significant outburst flood hazards if the dam is breached. While moraine subsurface structure and internal processes are likely to influence dam stability, only few sites have so far been investigated. We conducted electrical resistivity tomography (ERT) surveys at two sites on the terminal moraine complex of the Ngozumpa Glacier, Nepal, to aid assessment of future terminus stability. The resistivity signature of glacier ice at the site (100-15 kΩ m) is more consistent with values measured from cold glacier ice and while this may be feasible, uncertainties in the data inversion introduce ambiguity to this thermal interpretation. However, the ERT data does provide a significant improvement to our knowledge of the subsurface characteristics at these sites, clearly showing the presence (or absence) of glacier ice. Our interpretation is that of a highly complex latero-terminal moraine, resulting from interaction between previous glacier advance, recession and outburst flooding. If the base-level Spillway Lake continues to expand to a fully formed moraine-dammed glacial lake, the degradation of the ice core could have implications for glacial lake outburst risk.

SUB-SURFACE MERIDIONAL FLOW, VORTICITY, AND THE LIFETIME OF SOLAR ACTIVE REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurya, R. A.; Ambastha, A., E-mail: ramajor@prl.res.i, E-mail: ambastha@prl.res.i

Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic fields. Using the Doppler data obtained by the Global Oscillation Network Group project for a sample of 74 ARs, we have discovered the presence of steep gradients in meridional velocity at depths ranging from 1.5 to 5 Mm in flare productive ARs. The sample of these ARs is taken from the Carrington rotations 1980-2052 covering the period 2001 August-2007 January. The gradients showed an interesting hemisphericmore » trend of negative (positive) signs in the northern (southern) hemisphere, i.e., directed toward the equator. We have discovered three sheared layers in the depth range of 0-10 Mm, providing evidence of complex flow structures in several ARs. An important inference derived from our analysis is that the location of the deepest zero vertical vorticity is correlated with the remaining lifetime of ARs. This new finding may be employed as a tool for predicting the life expectancy of an AR.« less

Anatomy of terminal moraine segments and implied lake stability on Ngozumpa Glacier, Nepal, from electrical resistivity tomography (ERT)

PubMed Central

Thompson, Sarah S.; Kulessa, Bernd; Benn, Douglas I.; Mertes, Jordan R.

2017-01-01

Moraine-dammed lakes at debris-covered glaciers are becoming increasingly common and pose significant outburst flood hazards if the dam is breached. While moraine subsurface structure and internal processes are likely to influence dam stability, only few sites have so far been investigated. We conducted electrical resistivity tomography (ERT) surveys at two sites on the terminal moraine complex of the Ngozumpa Glacier, Nepal, to aid assessment of future terminus stability. The resistivity signature of glacier ice at the site (100–15 kΩ m) is more consistent with values measured from cold glacier ice and while this may be feasible, uncertainties in the data inversion introduce ambiguity to this thermal interpretation. However, the ERT data does provide a significant improvement to our knowledge of the subsurface characteristics at these sites, clearly showing the presence (or absence) of glacier ice. Our interpretation is that of a highly complex latero-terminal moraine, resulting from interaction between previous glacier advance, recession and outburst flooding. If the base-level Spillway Lake continues to expand to a fully formed moraine-dammed glacial lake, the degradation of the ice core could have implications for glacial lake outburst risk. PMID:28425458

Local Helioseismology of Emerging Active Regions: A Case Study

NASA Astrophysics Data System (ADS)

Kosovichev, Alexander G.; Zhao, Junwei; Ilonidis, Stathis

2018-04-01

Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the forming sunspots. These flows are most prominent in the depth range 1-3 Mm, and remain converging after the formation process is completed. On the larger scale converging flows around active region appear as a diversion of the zonal shearing flows towards the active region, accompanied by formation of a large-scale vortex structure. This process occurs when a substantial amount of the magnetic flux emerged on the surface, and the converging flow pattern remains stable during the following evolution of the active region. The Carrington synoptic flow maps show that the large-scale subsurface inflows are typical for active regions. In the deeper layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath some active regions. In addition, the synoptic maps reveal a complex evolving pattern of large-scale flows on the scale much larger than supergranulation

4D ground penetrating radar measurements as non-invasive means for hydrological process investigation

NASA Astrophysics Data System (ADS)

Jackisch, Conrad; Allroggen, Niklas

2017-04-01

The missing vision into the subsurface appears to be a major limiting factor for our hydrological process understanding and theory development. Today, hydrology-related sciences have collected tremendous evidence for soils acting as drainage network and retention stores simultaneously in structured and self-organising domains. However, our present observation technology relies mainly on point-scale sensors, which integrate over a volume of unknown structures and is blind for their distribution. Although heterogeneity is acknowledged at all scales, it is rarely seen as inherent system property. At small scales (soil moisture probe) and at large scales (neutron probe) our measurements leave quite some ambiguity. Consequently, spatially and temporally continuous measurement of soil water states is essential for advancing our understanding and development of subsurface process theories. We present results from several irrigation experiments accompanied by 2D and 3D time-lapse GPR for the development of a novel technique to visualise and quantify water dynamics in the subsurface. Through the comparison of TDR, tracer and gravimetric measurement of soil moisture it becomes apparent that all sensor-based techniques are capable to record temporal dynamics, but are challenged to precisely quantify the measurements and to extrapolate them in space. At the same time excavative methods are very limited in temporal and spatial resolution. The application of non-invasive 4D GPR measurements complements the existing techniques and reveals structural and temporal dynamics simultaneously. By consequently increasing the density of the GPR data recordings in time and space, we find means to process the data also in the time-dimension. This opens ways to quantitatively analyse soil water dynamics in complex settings.

Using dye tracing to establish groundwater flow paths in a limestone marble aquifer, University of California, Santa Cruz, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, J.; Bertschinger, V.; Aley, T.

1993-04-01

Areas underlain by karst aquifers are characterized by soluble rock with sinkholes, caves, and a complex underground drainage network. Groundwater issues such as flow direction, well pumping impacts, spring recharge areas, and potential contamination transport routes are greatly complicated by the unique structure of karst aquifers. Standard aquifer analysis techniques cannot be applied unless the structure of the karst aquifer is understood. Water soluble fluorescent dyes are a powerful tool for mapping the irregular subsurface connections and flow paths in karst aquifers. Mapping the subsurface connections allows reasonable estimates of the hydrologic behavior of the aquifer. Two different fluorescent dyesmore » were injected at two points in a limestone karst aquifer system beneath the University of California, Santa Cruz campus. Flow paths in the marble were thought to be closely tied to easily recognized geomorphic alignments of sinkholes associated with fault and fracture zones. The dye tests revealed unexpected and highly complex interconnections. These complex flow paths only partially corresponded to previous surface mapping and aerial photo analysis of fracture systems. Several interfingering but hydrologically unconnected flow paths evidently exist within the cavernous aquifer. For example, dye did not appear at some discharge springs close to the dye injection points, but did appear at more distant springs. This study shows how a dye tracing study in a small, well-defined limestone body can shed light on a variety of environmental and hydrological issues, including potential well pumping impact areas, wellhead protection and recharge areas, parking lot runoff injection to aquifers, and drainage routes from hazardous materials storage areas.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sentis, Manuel Lorenzo; Gable, Carl W.

Furthermore, there are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools willmore » provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. Here in this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.« less

Influence of subsurface defects on damage performance of fused silica in ultraviolet laser

NASA Astrophysics Data System (ADS)

Huang, Jin; Zhou, Xinda; Liu, Hongjie; Wang, Fengrui; Jiang, Xiaodong; Wu, Weidong; Tang, Yongjian; Zheng, Wanguo

2013-02-01

In ultraviolet pulse laser, damage performance of fused silica optics is directly dependent on the absorptive impurities and scratches in subsurface, which are induced by mechanical polishing. In the research about influence of subsurface defects on damage performance, a series of fused silica surfaces with various impurity concentrations and scratch structures were created by hydrofluoric (HF) acid solution etching. Time of Flight secondary ion mass spectrometry and scanning probe microprobe revealed that with increasing etching depth, impurity concentrations in subsurface layers are decreased, the scratch structures become smoother and the diameter:depth ratio is increased. Damage performance test with 355-nm pulse laser showed that when 600 nm subsurface thickness is removed by HF acid etching, laser-induced damage threshold of fused silica is raised by 40 percent and damage density is decreased by over one order of magnitude. Laser weak absorption was tested to explain the cause of impurity elements impacting damage performance, field enhancement caused by change of scratch structures was calculated by finite difference time domain simulation, and the calculated results are in accord with the damage test results.

Interpretive geologic cross sections for the Death Valley regional flow system and surrounding areas, Nevada and California

USGS Publications Warehouse

Sweetkind, D.S.; Dickerson, R.P.; Blakely, R.J.; Denning, Paul

2001-01-01

This report presents a network of 28 geologic cross sections that portray subsurface geologic relations within the Death Valley regional ground-water system, a ground-water basin that encompasses a 3? x 3? area (approximately 70,000 km2) in southern Nevada and eastern California. The cross sections transect that part of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain. The specific geometric relationships portrayed on the cross sections are discussed in the context of four general sub-regions that have stratigraphic similarities and general consistency of structural style: (1) the Nevada Test Site vicinity; (2) the Spring Mountains, Pahrump Valley and Amargosa Desert region; (3) the Death Valley region; and (4) the area east of the Nevada Test Site. The subsurface geologic interpretations portrayed on the cross sections are based on an integration of existing geologic maps, measured stratigraphic sections, published cross sections, well data, and geophysical data and interpretations. The estimated top of pre-Cenozoic rocks in the cross sections is based on inversion of gravity data, but the deeper parts of the sections are based on geologic conceptual models and are more speculative. The region transected by the cross sections includes part of the southern Basin and Range Province, the northwest-trending Walker Lane belt, the Death Valley region, and the northern Mojave Desert. The region is structurally complex, where a locally thick Tertiary volcanic and sedimentary section unconformably overlies previously deformed Proterozoic through Paleozoic rocks. All of these rocks have been deformed by complex Neogene ex-tensional normal and strike-slip faults. These cross sections form a three-dimensional network that portrays the interpreted stratigraphic and structural relations in the region; the sections form part of the geologic framework that will be incorporated in a complex numerical model of ground-water flow in the Death Valley region.

Subsurface Mapping: A Question of Position and Interpretation

ERIC Educational Resources Information Center

Kellie, Andrew C.

2009-01-01

This paper discusses the character and challenges inherent in the graphical portrayal of features in subsurface mapping. Subsurface structures are, by their nature, hidden and must be mapped based on drilling and/or geophysical data. Efficient use of graphical techniques is central to effectively communicating the results of expensive exploration…

Investigating the complex structural integrity of the Zeit Bay Field, Gulf of Suez, Egypt, using interpretation of 3D seismic reflection data

NASA Astrophysics Data System (ADS)

Afife, M.; Salem, M.; Aziz, M. Abdel

2017-07-01

Zeit Bay Field is one of the most important oil-bearing fields in the Gulf of Suez, Egypt, producing oil from the fractured basement rocks. Due to the complex structural setting of the area and the classical exploration concept that was based mainly on 2D seismic survey data, the area suffered from limited hydrocarbon interest for several years. During this time, most of the drilled wells hit structural highs and resulted in several dry holes. The present study is based on the interpretation of more recently acquired 3D seismic survey data as, matched with the available well logs, used to understand the complex structural setting of the Zeit Bay Field and provide insight into the entrapment style of the implied hydrocarbons. Several selected seismic cross sections were constructed, to extract subsurface geologic information, using available seismic profiles and wells. In addition, structure contour maps (isochronous maps, converted to depth maps) were constructed for the peaks of the basement, Nubian Sandstone, Kareem and Belayim Formations. Folds (anticlines and synclines) and faults (dip-slip) are identified on these maps, both individually and in groups, giving rise to step-like belts, as well as graben and horst blocks.

Device and nondestructive method to determine subsurface micro-structure in dense materials

DOEpatents

Sun, Jiangang [Westmont, IL

2006-05-09

A method and a device to detect subsurface three-dimensional micro-structure in a sample by illuminating the sample with light of a given polarization and detecting light emanating from the sample that has a different direction of polarization by means of a confocal optical system.

Seismic sensitivity to sub-surface solar activity from 18 yr of GOLF/SoHO observations

NASA Astrophysics Data System (ADS)

Salabert, D.; García, R. A.; Turck-Chièze, S.

2015-06-01

Solar activity has significantly changed over the last two Schwabe cycles. After a long and deep minimum at the end of Cycle 23, the weaker activity of Cycle 24 contrasts with the previous cycles. In this work, the response of the solar acoustic oscillations to solar activity is used in order to provide insights into the structural and magnetic changes in the sub-surface layers of the Sun during this on-going unusual period of low activity. We analyze 18 yr of continuous observations of the solar acoustic oscillations collected by the Sun-as-a-star GOLF instrument on board the SoHO spacecraft. From the fitted mode frequencies, the temporal variability of the frequency shifts of the radial, dipolar, and quadrupolar modes are studied for different frequency ranges that are sensitive to different layers in the solar sub-surface interior. The low-frequency modes show nearly unchanged frequency shifts between Cycles 23 and 24, with a time evolving signature of the quasi-biennial oscillation, which is particularly visible for the quadrupole component revealing the presence of a complex magnetic structure. The modes at higher frequencies show frequency shifts that are 30% smaller during Cycle 24, which is in agreement with the decrease observed in the surface activity between Cycles 23 and 24. The analysis of 18 yr of GOLF oscillations indicates that the structural and magnetic changes responsible for the frequency shifts remained comparable between Cycle 23 and Cycle 24 in the deeper sub-surface layers below 1400 km as revealed by the low-frequency modes. The frequency shifts of the higher-frequency modes, sensitive to shallower regions, show that Cycle 24 is magnetically weaker in the upper layers of Sun. Appendices are available in electronic form at http://www.aanda.orgThe following 68 GOLF frequency tables are available and Table A.1 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A137

Research Performed at NETL on the Subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Deep below our feet, lies the unique and complex world of the subsurface. A world that is improving the lives of Americans and brimming with the potential to generate even greater benefits through NETL research. NETL research supports industry by improving resource extraction while also helping to make carbon storage safe and more effective.

Radar Soundings of the Subsurface of Mars

NASA Technical Reports Server (NTRS)

Picardi, Giovanni; Plaut, Jeffrey J.; Biccari, Daniela; Bombaci, Ornella; Calabrese, Diego; Cartacci, Marco; Cicchetti, Andrea; Clifford, Stephen M.; Edenhofer, Peter; Farrell, William M.;

Subsurface architecture of a strike-slip collapse structure: insights from Ilopango caldera, El Salvador

NASA Astrophysics Data System (ADS)

Saxby, Jennifer; Gottsmann, Joachim; Cashman, Katherine; Gutierrez, Eduardo

2016-04-01

While most calderas are created by roof collapse along ring-like faults into an emptying magma reservoir during a large and violent explosive eruption, an additional condition for caldera formation may be tectonically induced extensional stresses. Here we provide geophysical insights into the shallow sub-volcanic plumbing system of a collapse caldera in a major strike-slip tectonic setting by inverting Bouguer gravity data from the Ilopango caldera in El Salvador. Despite a long history of catastrophic eruptions with the most recent in 500 A.D., the internal architecture of the caldera has not been investigated, although studies of the most recent eruption have not identified the ring faults commonly associated with caldera collapse. The gravity data show that low-density material aligned along the principal stress orientations of the El Salvador Fault Zone (ESFZ) forms a pronounced gravity low beneath the caldera. Extending to around 6 km depth, the low density structure likely maps a complex stacked shallow plumbing system composed of magmatic and fractured hydrothermal reservoirs. A substantial volume of the plumbing system must be composed of a vapour phase to explain the modeled negative density contrasts. We use these constraints to map the possible multi-phase parameter space contributing to the subsurface architecture of the caldera and propose that the local extension along the complex ESFZ controls accumulation, ascent and eruption of magma at Ilopango. The data further suggest that future eruptions at Ilopango could be facilitated by rapid rise of magma along conjugate fault damage zones through a mechanically weak crust under tension. This may explain the absence of clear ring fault structures at the caldera.

Subsurface geologic features of the 2011 central Virginia earthquakes revealed by airborne geophysics

USGS Publications Warehouse

Shah, Anjana K.; Horton, J. Wright; Burton, William C.; Spears, David B; Gilmer, Amy K

2014-01-01

Characterizing geologic features associated with major earthquakes provides insights into mechanisms contributing to fault slip and assists evaluation of seismic hazard. We use high-resolution airborne geophysical data combined with ground sample measurements to image subsurface geologic features associated with the 2011 moment magnitude (Mw) 5.8 central Virginia (USA) intraplate earthquake and its aftershocks. Geologic mapping and magnetic data analyses suggest that the earthquake occurred near a complex juncture of geologic contacts. These contacts also intersect a >60-km-long linear gravity gradient. Distal aftershocks occurred in tight, ~1-km-wide clusters near other obliquely oriented contacts that intersect gravity gradients, in contrast to more linearly distributed seismicity observed at other seismic zones. These data and corresponding models suggest that local density contrasts (manifested as gravity gradients) modified the nearby stress regime in a manner favoring failure. However, along those gradients seismic activity is localized near structural complexities, suggesting a significant contribution from variations in associated rock characteristics such as rheological weakness and/or rock permeability, which may be enhanced in those areas. Regional magnetic data show a broader bend in geologic structures within the Central Virginia seismic zone, suggesting that seismic activity may also be enhanced in other nearby areas with locally increased rheological weaknesses and/or rock permeability. In contrast, away from the Mw5.8 epicenter, geophysical lineaments are nearly continuous for tens of kilometers, especially toward the northeast. Continuity of associated geologic structures probably contributed to efficient propagation of seismic energy in that direction, consistent with moderate to high levels of damage from Louisa County to Washington, D.C., and neighboring communities.

High-resolution seismic profiling reveals faulting associated with the 1934 Ms 6.6 Hansel Valley earthquake (Utah, USA)

USGS Publications Warehouse

Bruno, Pier Paolo G.; Duross, Christopher; Kokkalas, Sotirios

2017-01-01

The 1934 Ms 6.6 Hansel Valley, Utah, earthquake produced an 8-km-long by 3-km-wide zone of north-south−trending surface deformation in an extensional basin within the easternmost Basin and Range Province. Less than 0.5 m of purely vertical displacement was measured at the surface, although seismologic data suggest mostly strike-slip faulting at depth. Characterization of the origin and kinematics of faulting in the Hansel Valley earthquake is important to understand how complex fault ruptures accommodate regions of continental extension and transtension. Here, we address three questions: (1) How does the 1934 surface rupture compare with faults in the subsurface? (2) Are the 1934 fault scarps tectonic or secondary features? (3) Did the 1934 earthquake have components of both strike-slip and dip-slip motion? To address these questions, we acquired a 6.6-km-long, high-resolution seismic profile across Hansel Valley, including the 1934 ruptures. We observed numerous east- and west-dipping normal faults that dip 40°−70° and offset late Quaternary strata from within a few tens of meters of the surface down to a depth of ∼1 km. Spatial correspondence between the 1934 surface ruptures and subsurface faults suggests that ruptures associated with the earthquake are of tectonic origin. Our data clearly show complex basin faulting that is most consistent with transtensional tectonics. Although the kinematics of the 1934 earthquake remain underconstrained, we interpret the disagreement between surface (normal) and subsurface (strike-slip) kinematics as due to slip partitioning during fault propagation and to the effect of preexisting structural complexities. We infer that the 1934 earthquake occurred along an ∼3-km wide, off-fault damage zone characterized by distributed deformation along small-displacement faults that may be alternatively activated during different earthquake episodes.

Method of installing subsurface barrier

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2007-10-09

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Subsurface materials management and containment system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kosteinik, Kevin M.; Sloan, Paul A.

2004-07-06

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Subsurface materials management and containment system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2006-10-17

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Differential Dynamic Engagement within 24 SH3 Domain: Peptide Complexes Revealed by Co-Linear Chemical Shift Perturbation Analysis

PubMed Central

Stollar, Elliott J.; Lin, Hong; Davidson, Alan R.; Forman-Kay, Julie D.

2012-01-01

There is increasing evidence for the functional importance of multiple dynamically populated states within single proteins. However, peptide binding by protein-protein interaction domains, such as the SH3 domain, has generally been considered to involve the full engagement of peptide to the binding surface with minimal dynamics and simple methods to determine dynamics at the binding surface for multiple related complexes have not been described. We have used NMR spectroscopy combined with isothermal titration calorimetry to comprehensively examine the extent of engagement to the yeast Abp1p SH3 domain for 24 different peptides. Over one quarter of the domain residues display co-linear chemical shift perturbation (CCSP) behavior, in which the position of a given chemical shift in a complex is co-linear with the same chemical shift in the other complexes, providing evidence that each complex exists as a unique dynamic rapidly inter-converting ensemble. The extent the specificity determining sub-surface of AbpSH3 is engaged as judged by CCSP analysis correlates with structural and thermodynamic measurements as well as with functional data, revealing the basis for significant structural and functional diversity amongst the related complexes. Thus, CCSP analysis can distinguish peptide complexes that may appear identical in terms of general structure and percent peptide occupancy but have significant local binding differences across the interface, affecting their ability to transmit conformational change across the domain and resulting in functional differences. PMID:23251481

Geophysical interpretations west of and within the northwestern part of the Nevada Test Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grauch, V.J.; Sawyer, D.A.; Fridrich, C.J.

1997-12-31

This report focuses on interpretation of gravity and new magnetic data west of the Nevada Test Site (NTS) and within the northwestern part of NTS. The interpretations integrate the gravity and magnetic data with other geophysical, geological, and rock property data to put constraints on tectonic and magmatic features not exposed at the surface. West of NTS, where drill hole information is absent, these geophysical data provide the best available information on the subsurface. Interpreted subsurface features include calderas, intrusions, basalt flows and volcanoes, Tertiary basins, structurally high pre-Tertiary rocks, and fault zones. New features revealed by this study includemore » (1) a north-south buried tectonic fault east of Oasis Mountain, which the authors call the Hogback fault; (2) an east striking fault or accommodation zone along the south side of Oasis Valley basin, which they call the Hot Springs fault; (3) a NNE striking structural zone coinciding with the western margins of the caldera complexes; (4) regional magnetic highs that probably represent a thick sequence of Tertiary volcanic rocks; and (5) two probable buried calderas that may be related to the tuffs of Tolicha Peak and of Sleeping Butte, respectively.« less

Assessment of integrated electrical resistivity data on complex aquifer structures in NE Nuba Mountains - Sudan

NASA Astrophysics Data System (ADS)

Mohamed, N. E.; Yaramanci, U.; Kheiralla, K. M.; Abdelgalil, M. Y.

2011-07-01

Two geophysical techniques were integrated to map the groundwater aquifers on complex geological settings, in the crystalline basement terrain in northeast Nuba Mountains. The water flow is structurally controlled by the northwest-southeast extensional faults as one of several in-situ deformational patterns that are attributed to the collision of the Pan-African oceanic assemblage of the Nubian shield against the pre-Pan African continental crust to the west. The structural lineaments and drainage systems have been enhanced by the remote sensing technique. The geophysical techniques used are: vertical electrical soundings (VES) and electrical resistivity tomography (ERT), in addition to hydraulic conductivity measurements. These measurements were designed to overlap in order to improve the producibility of the geophysical data and to provide a better interpretation of the hydrogeological setting of the aquifer complex structure. Smooth and Block inversion schemes were attempted for the observed ERT data to study their reliability in mapping the different geometries in the complex subsurface. The VES data was conducted where ERT survey was not accessible, and inverted smoothly and merged with the ERT in the 3D resistivity grid. The hydraulic conductivity was measured for 42 water samples collected from the distributed dug wells in the study area; where extremely high saline zones were recorded and have been compared to the resistivity values in the 3D model.

Near-Field Resonance Microwave Tomography and Holography

NASA Astrophysics Data System (ADS)

Gaikovich, K. P.; Smirnov, A. I.; Yanin, D. V.

2018-02-01

We develop the methods of electromagnetic computer near-field microwave tomography of distributed subsurface inhomogeneities of complex dielectric permittivity and of holography (shape retrieval) of internally homogeneous subsurface objects. The methods are based on the solution of the near-field inverse scattering problem from measurements of the resonance-parameter variations of microwave probes above the medium surface. The capabilities of the proposed diagnostic technique are demonstrated in the numerical simulation for sensors with a cylindrical capacitor as a probe element, the edge capacitance of which is sensitive to subsurface inhomogeneities.

Complex crustal structures: their 3D grav/mag modelling and 3D printing

NASA Astrophysics Data System (ADS)

Götze, Hans-Jürgen; Schmidt, Sabine; Menzel, Peter

2017-04-01

Our new techniques for modelling and visualization are user-friendly because they are highly interactive, ideally real-time and topology conserving and can be used for both flat and spherical models in 3D. These are important requirements for joint inversion for gravity and magnetic modelling of fields and their derivatives, constrained by seismic and structural input from independent data sources. A borehole tool for magnetic and gravity modelling will also be introduced. We are already close to satisfying the demand of treating several geophysical methods in a single model for subsurface evaluation purposes and aim now for fulfilling most of the constraints: consistency of modelling results and measurements and geological plausibility as well. For 3D modelling, polyhedrons built by triangles are used. All elements of the gravity and magnetic tensors can be included. In the modelling interface, after geometry changes the effect on the model is quickly updated because only the changed triangles have to be recalculated. Because of the triangular model structure, our approach can handle complex structures very well and flexible (e.g. overhangs of salt domes or plumes). For regional models, the use of spherical geometries and calculations is necessary and available. 3D visualization is performed with a 3D-printer (Ultimaker 2) and gives new insights into even rather complicated Earth subsurface structures. Inversion can either be run over the whole model, but typically it is used in smaller parts of the model, helping to solve local problems and/or proving/disproving local hypotheses. The basic principles behind this interactive approach are high performance optimized algorithms (CMA-ES: Covariance-matrix-adoption-evolution-strategy). The efficiency of the algorithm is rather good in terms of stable convergence due to topological model validity. Potential field modelling is always influenced by edge effects. To avoid this, a simple but very robust method has been developed: Derive a density/susceptibility-depth function by taking the mean value of the borders of depth slices through the model. The focus of the presentation is set on two practical examples: From the international KTB - Project, Germanýs deep continental borehole as well as a very complex salt structure in the Northwest German Basin.

76 FR 70057 - National Oil and Hazardous Substance Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-10

... surface soils, subsurface soils, structures and groundwater within the boundaries of these parcels. In... soils, subsurface soils, structures and groundwater within the boundaries of the non-ETA part of PIN 05... additional contaminated groundwater and soil within the Site. On November 25, 2005 EPA partially deleted the...

Beacon Hill end moraine, Boston: new explanation of an important urban feature

USGS Publications Warehouse

Kaye, Clifford A.; Coates, Donald R.

1976-01-01

The usefulness of geology to engineers is in direct proportion to how well it helps us predict the subsurface; these predictions, in turn, depend on our knowledge of the geomorphic processes that molded the terrain. The uncertainties of interpretation are particularly great in glaciated terrain because our understanding of both glacial processes and history is so incomplete, a fact well illustrated in Beacon Hill. Recent construction activities in the eastern part of the hill, until now classified as a drumlin, have shown that it is better interpreted as an end moraine formed by a Wisconsonian glacial readvance. Instead of the firm till that was anticipated as foundation material, excavations exposed a complex of sand, gravel, and clay, with only minor zones of till. The structure of these deposits strongly suggests that originally they were plates of the glacial bed that froze to the glacier and were transported englacially. Thrust faulting and other deformations are glacial structures formed within the ice in the glacier's terminal zone. In spite of the complex englacial history, these deposits lost little of their original appearance and intergranular relationships. Upon deglaciation, the frozen moraine thawed, and slumping formed complex secondary structures on the ridge's lower flanks.

Modeling the effects of structure on seismic anisotropy in the Chester gneiss dome, southeast Vermont

NASA Astrophysics Data System (ADS)

Saif, S.; Brownlee, S. J.

2017-12-01

Compositional and structural heterogeneity in the continental crust are factors that contribute to the complex expression of crustal seismic anisotropy. Understanding deformation and flow in the crust using seismic anisotropy has thus proven difficult. Seismic anisotropy is affected by rock microstructure and mineralogy, and a number of studies have begun to characterize the full elastic tensors of crustal rocks in an attempt to increase our understanding of these intrinsic factors. However, there is still a large gap in length-scale between laboratory characterization on the scale of centimeters and seismic wavelengths on the order of kilometers. To address this length-scale gap we are developing a 3D crustal model that will help us determine the effects of rotating laboratory-scale elastic tensors into field-scale structures. The Chester gneiss dome in southeast Vermont is our primary focus. The model combines over 2000 structural data points from field measurements and published USGS structural data with elastic tensors of Chester dome rocks derived from electron backscatter diffraction data. We created a uniformly spaced grid by averaging structural measurements together in equally spaced grid boxes. The surface measurements are then projected into the third dimension using existing subsurface interpretations. A measured elastic tensor for the specific rock type is rotated according to its unique structural input at each point in the model. The goal is to use this model to generate artificial seismograms using existing numerical wave propagation codes. Once completed, the model input can be varied to examine the effects of different subsurface structure interpretations, as well as heterogeneity in rock composition and elastic tensors. Our goal is to be able to make predictions for how specific structures will appear in seismic data, and how that appearance changes with variations in rock composition.

Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy

USDA-ARS?s Scientific Manuscript database

The dual beam scanning electron microscope, equipped with both a focused ion- and scanning electron- beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB is capable of removing small cross sections to view the subsurface features and may be s...

Method of sealing casings of subsurface materials management system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2007-02-06

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Subsurface Optical Microscopy of Coarse Grain Spinels. Phase 1

DTIC Science & Technology

2013-12-01

A 456 nm LED line bar illuminated in figure 15 and a Xenon fiber optic bar illuminator is shown for figure 16. The optical in situ or subsurface ... imaging of coarse grain spinels and AlONs is optically more complex than expected. An overhead view of the side illumination field is shown in figure 20

Possible Habilability of Martian Regolity and Research of Ancient Life "Biomarkers"

NASA Astrophysics Data System (ADS)

Pavlov, A. K.

2017-05-01

We consider environments of modern subsurface martian regolith layer as possible habitats of the terrestrial like microorganisms. Recent experimental studies demonstrate that low atmospheric pressure, low temperature and high level of cosmic rays ionizing radiation are not able to sterilize the subsurface layer of Mars. Even nonextremofile microorganisms can reproduce in martian regolith using films of liquid water which are produced by absorption of water vapor of subsurface ice sublimation. Areas of possible seasonal subsurface water flow (recurring slope lineae, dark dune spots) and methane emission regions are discussed as perspective sites for discovering of modern life on Mars. Degradation of "biomarkers" (complex organic molecules and isotopic ratio 13C/12C) in martian soil under high level of cosmic rays radiation is analyzed. We show the ancient biomarkers are effectively destroyed within period 108 -109 years. As result, probability of its discovering in shallow subsurface martian layer is low.

Anatomy of Old Faithful From Subsurface Seismic Imaging of the Yellowstone Upper Geyser Basin

NASA Astrophysics Data System (ADS)

Wu, Sin-Mei; Ward, Kevin M.; Farrell, Jamie; Lin, Fan-Chi; Karplus, Marianne; Smith, Robert B.

2017-10-01

The Upper Geyser Basin in Yellowstone National Park contains one of the highest concentrations of hydrothermal features on Earth including the iconic Old Faithful geyser. Although this system has been the focus of many geological, geochemical, and geophysical studies for decades, the shallow (<200 m) subsurface structure remains poorly characterized. To investigate the detailed subsurface geologic structure including the hydrothermal plumbing of the Upper Geyser Basin, we deployed an array of densely spaced three-component nodal seismographs in November of 2015. In this study, we extract Rayleigh wave seismic signals between 1 and 10 Hz utilizing nondiffusive seismic waves excited by nearby active hydrothermal features with the following results: (1) imaging the shallow subsurface structure by utilizing stationary hydrothermal activity as a seismic source, (2) characterizing how local geologic conditions control the formation and location of the Old Faithful hydrothermal system, and (3) resolving a relatively shallow (10-60 m) and large reservoir located 100 m southwest of Old Faithful geyser.

Long-term in situ oxidation of biogenic uraninite in an alluvial aquifer: impact of dissolved oxygen and calcium.

PubMed

Lezama-Pacheco, Juan S; Cerrato, José M; Veeramani, Harish; Alessi, Daniel S; Suvorova, Elena; Bernier-Latmani, Rizlan; Giammar, Daniel E; Long, Philip E; Williams, Kenneth H; Bargar, John R

2015-06-16

Oxidative dissolution controls uranium release to (sub)oxic pore waters from biogenic uraninite produced by natural or engineered processes, such as bioremediation. Laboratory studies show that uraninite dissolution is profoundly influenced by dissolved oxygen (DO), carbonate, and solutes such as Ca(2+). In complex and heterogeneous subsurface environments, the concentrations of these solutes vary in time and space. Knowledge of dissolution processes and kinetics occurring over the long-term under such conditions is needed to predict subsurface uranium behavior and optimize the selection and performance of uraninite-based remediation technologies over multiyear periods. We have assessed dissolution of biogenic uraninite deployed in wells at the Rifle, CO, DOE research site over a 22 month period. Uraninite loss rates were highly sensitive to DO, with near-complete loss at >0.6 mg/L over this period but no measurable loss at lower DO. We conclude that uraninite can be stable over decadal time scales in aquifers under low DO conditions. U(VI) solid products were absent over a wide range of DO values, suggesting that dissolution proceeded through complexation and removal of oxidized surface uranium atoms by carbonate. Moreover, under the groundwater conditions present, Ca(2+) binds strongly to uraninite surfaces at structural uranium sites, impacting uranium fate.

Aggregating todays data for tomorrows science: a geological use case

NASA Astrophysics Data System (ADS)

Glaves, H.; Kingdon, A.; Nayembil, M.; Baker, G.

2016-12-01

Geoscience data is made up of diverse and complex smaller datasets that, when aggregated together, build towards what is recognised as `big data'. The British Geological Survey (BGS), which acts as a repository for all subsurface data from the United Kingdom, has been collating these disparate small datasets that have been accumulated from the activities of a large number of geoscientists over many years. Recently this picture has been further complicated by the addition of new data sources such as near real-time sensor data, and industry or community data that is increasingly delivered via automatic donations. Many of these datasets have been aggregated in relational databases to form larger ones that are used to address a variety of issues ranging from development of national infrastructure to disaster response. These complex domain-specific SQL databases deliver effective data management using normalised subject-based database designs in a secure environment. However, the isolated subject-oriented design of these systems inhibits efficient cross-domain querying of the datasets. Additionally, the tools provided often do not enable effective data discovery as they have problems resolving the complex underlying normalised structures. Recent requirements to understand sub-surface geology in three dimensions have led BGS to develop new data systems. One such solution is PropBase which delivers a generic denormalised data structure within an RDBMS to store geological property data. Propbase facilitates rapid and standardised data discovery and access, incorporating 2D and 3D physical and chemical property data, including associated metadata. It also provides a dedicated web interface to deliver complex multiple data sets from a single database in standardised common output formats (e.g. CSV, GIS shape files) without the need for complex data conditioning. PropBase facilitates new scientific research, previously considered impractical, by enabling property data searches across multiple databases. Using the Propbase exemplar this presentation will seek to illustrate how BGS has developed systems for aggregating `small datasets' to create the `big data' necessary for the data analytics, mining, processing and visualisation needed for future geoscientific research.

Subsurface materials management and containment system, components thereof and methods relating thereto

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2006-04-18

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Fold-Thrust mapping using photogrammetry in Western Champsaur basin, SE France

NASA Astrophysics Data System (ADS)

Totake, Y.; Butler, R.; Bond, C. E.

2016-12-01

There is an increasing demand for high-resolution geometric data for outcropping geological structures - not only to test models for their formation and evolution but also to create synthetic seismic visualisations for comparison with subsurface data. High-resolution 3D scenes reconstructed by modern photogrammetry offer an efficient toolbox for such work. When integrated with direct field measurements and observations, these products can be used to build geological interpretations and models. Photogrammetric techniques using standard equipment are ideally suited to working in the high mountain terrain that commonly offers the best outcrops, as all equipment is readily portable and, in the absence of cloud-cover, not restricted to the meteorological and legal restrictions that can affect some airborne approaches. The workflows and approaches for generating geological models utilising such photogrammetry techniques are the focus of our contribution. Our case study comes from SE France where early Alpine fore-deep sediments have been deformed into arrays of fold-thrust complexes. Over 1500m vertical relief provides excellent outcrop control with surrounding hillsides providing vantage points for ground-based photogrammetry. We collected over 9,400 photographs across the fold-thrust array using a handheld digital camera from 133 ground locations that were individually georeferenced. We processed the photographic images within the software PhotoScan-Pro to build 3D landscape scenes. The built photogrammetric models were then imported into the software Move, along with field measurements, to map faults and sedimentary layers and to produce geological cross sections and 3D geological surfaces. Polylines of sediment beds and faults traced on our photogrammetry models allow interpretation of a pseudo-3D geometry of the deformation structures, and enable prediction of dips and strikes from inaccessible field areas, to map the complex geometries of the thrust faults and deformed strata in detail. The resultant structural geometry of the thrust zones delivers an exceptional analogue to inaccessible subsurface fold-thrust structures which are often challenging to obtain a clear seismic image.

Bahía de Banderas, Mexico: Morphology, Magnetic Anomalies and Shallow Structure

NASA Astrophysics Data System (ADS)

Mortera Gutiérrez, Carlos A.; Bandy, William L.; Ponce Núñez, Francisco; Pérez Calderón, Daniel A.

2016-10-01

The Bahía de Banderas lies within a tectonically complex area at the northern end of the Middle America Trench. The structure, morphology, subsurface geology and tectonic history of the bay are essential for unraveling the complex tectonic processes occurring in this area. With this focus, marine geophysical data (multi-beam bathymetry, high resolution seismic reflection and total field magnetic data) were collected within the bay and adjacent areas during four campaigns aboard the B.O. EL PUMA conducted in 2006 and 2009. These data image the detailed morphology of, and sedimentation patterns within, the Banderas Canyon (a prominent submarine canyon situated on the south side of the bay) as well as the shallow subsurface structure of the northern part of the bay and the submarine Marietas Ridge, which bounds the bay to the west. We find that the Marietas Ridge is presently a transtensional feature; the course of the Banderas Canyon is controlled by extensive turbidite fan sedimentation in its eastern extremity and by structural lineaments to the west; the canyon floor is filled by sediments and exhibits almost no evidence for recent tectonic movements; the southern canyon wall is quite steep and a few sediments are deposited as submarine fans at the base of the southern wall; and extensive turbidite fans form the lower part of the northern canyon wall, producing a gently sloping lower northern wall. We find no evidence for a regional east-west striking lineament between the bay and the Middle America Trench, which casts doubts on the previous assertion that the Banderas Canyon is unequivocally related to the presence of a regional half-graben. Finally, a N71°E oriented normal fault offsets the seafloor reflector by 15 m within the central part of the bay, suggesting that the bay is currently being subjected to NNW-SSE extension.

Working Smarter Not Harder - Developing a Virtual Subsurface Data Framework for U.S. Energy R&D

NASA Astrophysics Data System (ADS)

Rose, K.; Baker, D.; Bauer, J.; Dehlin, M.; Jones, T. J.; Rowan, C.

2017-12-01

The data revolution has resulted in a proliferation of resources that span beyond commercial and social networking domains. Research, scientific, and engineering data resources, including subsurface characterization, modeling, and analytical datasets, are increasingly available through online portals, warehouses, and systems. Data for subsurface systems is still challenging to access, discontinuous, and varies in resolution. However, with the proliferation of online data there are significant opportunities to advance access and knowledge of subsurface systems. The Energy Data eXchange (EDX) is an online platform designed to address research data needs by improving access to energy R&D products through advanced search capabilities. In addition, EDX hosts private, virtualized computational workspaces in support of multi-organizational R&D. These collaborative workspaces allow teams to share working data resources and connect to a growing number of analytical tools to support research efforts. One recent application, a team digital data notebook tool, called DataBook, was introduced within EDX workspaces to allow teams to capture contextual and structured data resources. Starting with DOE's subsurface R&D community, the EDX team has been developing DataBook to support scientists and engineers working on subsurface energy research, allowing them to contribute and curate both structured and unstructured data and knowledge about subsurface systems. These resources span petrophysical, geologic, engineering, geophysical, interpretations, models, and analyses associated with carbon storage, water, oil, gas, geothermal, induced seismicity and other subsurface systems to support the development of a virtual subsurface data framework. The integration of EDX and DataBook allows for these systems to leverage each other's best features, such as the ability to interact with other systems (Earthcube, OpenEI.net, NGDS, etc.) and leverage custom machine learning algorithms and capabilities to enhance user experience, make access and connection to relevant subsurface data resources more efficient for research teams to use, analyze and draw insights. Ultimately, the public and private resources in EDX seek to make subsurface energy research more efficient, reduce redundancy, and drive innovation.

Structural evolution of Cenozoic basins in northeastern Tunisia, in response to sinistral strike-slip movement on the El Alia-Teboursouk Fault

NASA Astrophysics Data System (ADS)

Bejaoui, Hamida; Aïfa, Tahar; Melki, Fetheddine; Zargouni, Fouad

2017-10-01

This paper resolves the structural complexity of Cenozoic sedimentary basins in northeastern Tunisia. These basins trend NE-SW to ∼ E-W, and are bordered by old fracture networks. Detailed descriptions of the structural features in outcrop and in subsurface data suggest that the El Alia-Teboursouk Fault zone in the Bizerte area evolved through a series of tectonic events. Cross sections, lithostratigraphic correlations, and interpretation of seismic profiles through the basins show evidence for: (i) a Triassic until Jurassic-Early Cretaceous rifting phase that induced lateral variations of facies and strata thicknesses; (ii) a set of faults oriented NE-SW, NW-SE, N-S, and E-W that guided sediment accumulation in pull-apart basins, which were subject to compressive and transpressive deformation during Eocene (Lutetian-Priabonian), Miocene (Tortonian), and Pliocene-Quaternary; and (iii) NNW-SSE to NS contractional events that occurred during the Late Pliocene. Part of the latest phase has been the formation of different synsedimentary folded structures with significant subsidence inversion. Such events have been responsible for the reactivation of inherited faults, and the intrusion of Triassic evaporites, ensuring the role of a slip layer. The combined effects of the different paleoconstraints and halokinetic movements are at the origin of the evolution of these pull-apart basins. The subsurface data suggest that an important fault displacement occurred during the Mesozoic-Cenozoic. The patterns of sediment accumulation in the different basins reflect a high activity of deep ancient faults.

Uncertainty analysis of multi-rate kinetics of uranium desorption from sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiaoying; Liu, Chongxuan; Hu, Bill X.

2014-01-01

A multi-rate expression for uranyl [U(VI)] surface complexation reactions has been proposed to describe diffusion-limited U(VI) sorption/desorption in heterogeneous subsurface sediments. An important assumption in the rate expression is that its rate constants follow a certain type probability distribution. In this paper, a Bayes-based, Differential Evolution Markov Chain method was used to assess the distribution assumption and to analyze parameter and model structure uncertainties. U(VI) desorption from a contaminated sediment at the US Hanford 300 Area, Washington was used as an example for detail analysis. The results indicated that: 1) the rate constants in the multi-rate expression contain uneven uncertaintiesmore » with slower rate constants having relative larger uncertainties; 2) the lognormal distribution is an effective assumption for the rate constants in the multi-rate model to simualte U(VI) desorption; 3) however, long-term prediction and its uncertainty may be significantly biased by the lognormal assumption for the smaller rate constants; and 4) both parameter and model structure uncertainties can affect the extrapolation of the multi-rate model with a larger uncertainty from the model structure. The results provide important insights into the factors contributing to the uncertainties of the multi-rate expression commonly used to describe the diffusion or mixing-limited sorption/desorption of both organic and inorganic contaminants in subsurface sediments.« less

Estimation of subsurface thermal structure using sea surface height and sea surface temperature

NASA Technical Reports Server (NTRS)

Kang, Yong Q. (Inventor); Jo, Young-Heon (Inventor); Yan, Xiao-Hai (Inventor)

2012-01-01

A method of determining a subsurface temperature in a body of water is disclosed. The method includes obtaining surface temperature anomaly data and surface height anomaly data of the body of water for a region of interest, and also obtaining subsurface temperature anomaly data for the region of interest at a plurality of depths. The method further includes regressing the obtained surface temperature anomaly data and surface height anomaly data for the region of interest with the obtained subsurface temperature anomaly data for the plurality of depths to generate regression coefficients, estimating a subsurface temperature at one or more other depths for the region of interest based on the generated regression coefficients and outputting the estimated subsurface temperature at the one or more other depths. Using the estimated subsurface temperature, signal propagation times and trajectories of marine life in the body of water are determined.

Extrapolating surface structures to depth in transpressional systems: the role of rheology and convergence angle deduced from analogue experiments

NASA Astrophysics Data System (ADS)

Hsieh, S. Y.; Neubauer, F.; Willingshofer, E.; Sokoutis, D.

2014-12-01

The internal structure of major strike-slip faults is still poorly understood, particularly how the deep structure could be inferred from its surface expression (Molnar and Dayem, 2011). Previous analogue experiments suggest that the convergence angle is the most influential factor (Leever et al., 2011). Further analogue modeling may allow a better understanding how to extrapolate surface structures to the subsurface geometry of strike-slip faults. Various scenarios of analogue experiments were designed to represent strike-slip faults in nature from different geological settings. As such key parameters, which are investigated in this study include: (a) the angle of convergence, (b) the thickness of brittle layer, (c) the influence of a rheological weak layer within the crust, and (d) influence of a thick and rheologically weak layer at the base of the crust. The latter aimed to simulate the effect of a hot metamorphic core complex or an alignment of uprising plutons bordered by a transtensional/transpressional strike-slip fault. The preliminary results show that convergence angle significantly influences the overall geometry of the transpressive system with greater convergence angles resulting in wider fault zones and higher elevation. Different positions, densities and viscosities of weak rheological layers have not only different surface expressions but also affect the fault geometry in the subsurface. For instance, rheological weak material in the bottom layer results in stretching when experiment reaches a certain displacement and a buildup of a less segmented, wide positive flower structure. At the surface, a wide fault valley in the middle of the fault zone is the reflection of stretching along the velocity discontinuity at depth. In models with a thin and rheologically weaker layer in the middle of the brittle layer, deformation is distributed over more faults and the geometry of the fault zone below and above the weak zone shows significant differences. This latter experiment has significantly similar phenomena in reality, such as few pressure ridges along Altyn fault. The experimental results underline the need to understand the role of the convergence angle and the influence of rheology on fault evolution, in order to connect between surface deformation and subsurface geometry.

Subsurface geology of the Lusi region: preliminary results from a comprehensive seismic-stratigraphic study.

NASA Astrophysics Data System (ADS)

Moscariello, Andrea; Do Couto, Damien; Lupi, Matteo; Mazzini, Adriano

2016-04-01

We investigate the subsurface data of a large sector in the Sidoarjo district (East Java, Indonesia) where the sudden catastrophic Lusi eruption started the 26th May 2006. Our goal is to understand the stratigraphic and structural features which can be genetically related to the surface manifestations of deep hydrothermal fluids and thus allow us to predict possible future similar phenomena in the region. In the framework of the Lusi Lab project (ERC grant n° 308126) we examined a series of densely spaced 2D reflection commercial seismic lines This allowed the reconstruction of the lateral variability of key stratigraphic horizons as well as the main tectonic features. In particular, we shed light on the deep structure of the Watukosek fault system and the associated fracture corridors crossing the entire stratigraphic successions. To the South-West, when approaching the volcanic complex, we could identify a clear contrast in seismic facies between chaotic volcanoclastic wedges and clastic-prone sedimentary successions as well as between the deeper stratigraphic units consisting of carbonates and lateral shales units. The latter show possible ductile deformation associated to fault-controlled diapirism which control in turns deformation of overlying stratigraphic units and deep geo-fluids circulation. Large collapse structures recognized in the study area (e.g. well PRG-1) are interpreted as the results of shale movement at depth. Similarly to Lusi, vertical deformation zones ("pipes"), likely associated with deeply rooted strike-slip systems seem to be often located at the interface between harder carbonate rocks forming isolated build ups and the laterally nearby clastic (shale-prone)-units. The mechanisms of deformation of structural features (strike vs dip slip systems) which may affect either the basement rock or the overlying deeper stratigraphic rocks is also being investigated to understand the relationship between deep and shallower (i.e. meteoric) fluid circulation. Seismic stratigraphic study of the basin margin (closer to volcanic accumulations) will also allow reconstructing the relationships between present and past volcanic activity recorded in the deep subsurface with the genesis of piercement structures and development of vertical deformation zones

Application of field geophysics in geomorphology: Advances and limitations exemplified by case studies

NASA Astrophysics Data System (ADS)

Schrott, Lothar; Sass, Oliver

2008-01-01

During the last decade, the use of geophysical techniques has become popular in many geomorphological studies. However, the correct handling of geophysical instruments and the subsequent processing of the data they yield are difficult tasks. Furthermore, the description and interpretation of geomorphological settings to which they apply can significantly influence the data gathering and subsequent modelling procedure ( e.g. achieving a maximum depth of 30 m requires a certain profile length and geophone spacing or a particular frequency of antenna). For more than three decades geophysical techniques have been successfully applied, for example, in permafrost studies. However, in many cases complex or more heterogeneous subsurface structures could not be adequately interpreted due to limited computer facilities and time consuming calculations. As a result of recent technical improvements, geophysical techniques have been applied to a wider spectrum of geomorphological and geological settings. This paper aims to present some examples of geomorphological studies that demonstrate the powerful integration of geophysical techniques and highlight some of the limitations of these techniques. A focus has been given to the three most frequently used techniques in geomorphology to date, namely ground-penetrating radar, seismic refraction and DC resistivity. Promising applications are reported for a broad range of landforms and environments, such as talus slopes, block fields, landslides, complex valley fill deposits, karst and loess covered landforms. A qualitative assessment highlights suitable landforms and environments. The techniques can help to answer yet unsolved questions in geomorphological research regarding for example sediment thickness and internal structures. However, based on case studies it can be shown that the use of a single geophysical technique or a single interpretation tool is not recommended for many geomorphological surface and subsurface conditions as this may lead to significant errors in interpretation. Because of changing physical properties of the subsurface material ( e.g. sediment, water content) in many cases only a combination of two or sometimes even three geophysical methods gives sufficient insight to avoid serious misinterpretation. A "good practice guide" has been framed that provides recommendations to enable the successful application of three important geophysical methods in geomorphology and to help users avoid making serious mistakes.

Evaluating the effectiveness of the MASW technique in a geologically complex terrain

NASA Astrophysics Data System (ADS)

Anukwu, G. C.; Khalil, A. E.; Abdullah, K. B.

2018-04-01

MASW surveys carried at a number of sites in Pulau Pinang, Malaysia, showed complicated dispersion curves which consequently made the inversion into soil shear velocity model ambiguous. This research work details effort to define the source of these complicated dispersion curves. As a starting point, the complexity of the phase velocity spectrum is assumed to be due to either the surveying parameters or the elastic properties of the soil structures. For the former, the surveying was carried out using different parameters. The complexities were persistent for the different surveying parameters, an indication that the elastic properties of the soil structure could be the reason. In order to exploit this assumption, a synthetic modelling approach was adopted using information from borehole, literature and geologically plausible models. Results suggest that the presence of irregular variation in the stiffness of the soil layers, high stiffness contrast and relatively shallow bedrock, results in a quite complex f-v spectrum, especially at frequencies lower than 20Hz, making it difficult to accurately extract the dispersion curve below this frequency. As such, for MASW technique, especially in complex geological situations as demonstrated, great care should be taken during the data processing and inversion to obtain a model that accurately depicts the subsurface.

Imaging Saltwater Intrusion Along the Coast of Monterey Bay Using Long-Offset Electrical Resistivity Tomography

NASA Astrophysics Data System (ADS)

Goebel, M.; Knight, R. J.; Pidlisecky, A.

2016-12-01

Coastal regions represent a complex dynamic interface where saltwater intrusion moves seawater landward and groundwater discharge moves freshwater seaward. These processes can have a dramatic impact on water quality, affecting both humans and coastal ecosystems. The ability to map the subsurface distribution of fresh and salt water is a critical step in predicting and managing water quality in coastal regions. This is commonly accomplished using wells, which are expensive and provide point information, which may fail to capture the spatial complexity in subsurface conditions. We present an alternate method for acquiring data, long-offset Electrical Resistivity Tomography (ERT), which is non-invasive, cost effective, and can address the problem of poor spatial sampling. This geophysical method can produce continuous profiles of subsurface electrical resistivity to a depth of 300 m, with spatial resolution on the order of tens of meters. Our research focuses on the Monterey Bay region, where sustained groundwater extraction over the past century has led to significant saltwater intrusion. ERT was acquired along 40 kilometers of the coast using the roll along method, allowing for continuous overlap in data acquisition. Electrodes were spaced every 22.2 m, with a total of 81 electrodes along the 1.8 km active cable length. The data show a complex distribution of fresh and salt water, influenced by geology, groundwater pumping, recharge, and land-use. While the inverted ERT resistivity profiles correspond well with existing data sets and geologic interpretations in the region, the spatial complexity revealed through the ERT data goes beyond what is known from traditional data sources alone. This leads us to conclude that this form of data can be extremely useful in informing and calibrating groundwater flow models, making targeted management decisions, and monitoring changes in subsurface salinities over time.

Stretchable ultrasonic transducer arrays for three-dimensional imaging on complex surfaces

PubMed Central

Zhu, Xuan; Li, Xiaoshi; Chen, Zeyu; Chen, Yimu; Lei, Yusheng; Li, Yang; Nomoto, Akihiro; Zhou, Qifa; di Scalea, Francesco Lanza

2018-01-01

Ultrasonic imaging has been implemented as a powerful tool for noninvasive subsurface inspections of both structural and biological media. Current ultrasound probes are rigid and bulky and cannot readily image through nonplanar three-dimensional (3D) surfaces. However, imaging through these complicated surfaces is vital because stress concentrations at geometrical discontinuities render these surfaces highly prone to defects. This study reports a stretchable ultrasound probe that can conform to and detect nonplanar complex surfaces. The probe consists of a 10 × 10 array of piezoelectric transducers that exploit an “island-bridge” layout with multilayer electrodes, encapsulated by thin and compliant silicone elastomers. The stretchable probe shows excellent electromechanical coupling, minimal cross-talk, and more than 50% stretchability. Its performance is demonstrated by reconstructing defects in 3D space with high spatial resolution through flat, concave, and convex surfaces. The results hold great implications for applications of ultrasound that require imaging through complex surfaces. PMID:29740603

The Development of 3d Sub-Surface Mapping Scheme and its Application to Martian Lobate Debris Aprons

NASA Astrophysics Data System (ADS)

Baik, H.; Kim, J.

2017-07-01

The Shallow Subsurface Radar (SHARAD), a sounding radar equipped on the Mars Reconnaissance Orbiter (MRO), has produced highly valuable information about the Martian subsurface. In particular, the complicated substructures of Mars such as polar deposit, pedestal crater and the other geomorphic features involving possible subsurface ice body has been successfully investigated by SHARAD. In this study, we established a 3D subsurface mapping strategy employing the multiple SHARAD profiles. A number of interpretation components of SHARAD signals were integrated into a subsurface mapping scheme using radargram information and topographic data, then applied over a few mid latitude Lobate Debris Aprons (LDAs). From the identified subsurface layers of LDA, and the GIS data base incorporating the other interpretation outcomes, we are expecting to trace the origin of LDAs. Also, the subsurface mapping scheme developed in this study will be further applied to other interesting Martian geological features such as inter crater structures, aeolian deposits and fluvial sediments. To achieve higher precision sub-surface mapping, the clutter simulation employing the high resolution topographic data and the upgraded clustering algorithms assuming multiple sub-surface layers will be also developed.

Effect of subsurface drainage on the structural capacity of flexible pavement.

DOT National Transportation Integrated Search

2005-01-01

Following the recommendation of the Virginia Transportation Research Council's Pavement Research Advisory Committee, this project was initiated to determine the effectiveness of including subsurface drainage systems in pavements in Virginia. The rese...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoak, T.E.; Klawitter, A.L.

Fractured production trends in Piceance Basin Cretaceous-age Mesaverde Group gas reservoirs are controlled by subsurface structures. Because many of the subsurface structures are controlled by basement fault trends, a new interpretation of basement structure was performed using an integrated interpretation of Landsat Thematic Mapper (TM), side-looking airborne radar (SLAR), high altitude, false color aerial photography, gas and water production data, high-resolution aeromagnetic data, subsurface geologic information, and surficial fracture maps. This new interpretation demonstrates the importance of basement structures on the nucleation and development of overlying structures and associated natural fractures in the hydrocarbon-bearing section. Grand Valley, Parachute, Rulison, Plateau,more » Shire Gulch, White River Dome, Divide Creek and Wolf Creek fields all produce gas from fractured tight gas sand and coal reservoirs within the Mesaverde Group. Tectonic fracturing involving basement structures is responsible for development of permeability allowing economic production from the reservoirs. In this context, the significance of detecting natural fractures using the intergrated fracture detection technique is critical to developing tight gas resources. Integration of data from widely-available, relatively inexpensive sources such as high-resolution aeromagnetics, remote sensing imagery analysis and regional geologic syntheses provide diagnostic data sets to incorporate into an overall methodology for targeting fractured reservoirs. The ultimate application of this methodology is the development and calibration of a potent exploration tool to predict subsurface fractured reservoirs, and target areas for exploration drilling, and infill and step-out development programs.« less

Quantitative Subsurface Atomic Structure Fingerprint for 2D Materials and Heterostructures by First-Principles-Calibrated Contact-Resonance Atomic Force Microscopy.

PubMed

Tu, Qing; Lange, Björn; Parlak, Zehra; Lopes, Joao Marcelo J; Blum, Volker; Zauscher, Stefan

2016-07-26

Interfaces and subsurface layers are critical for the performance of devices made of 2D materials and heterostructures. Facile, nondestructive, and quantitative ways to characterize the structure of atomically thin, layered materials are thus essential to ensure control of the resultant properties. Here, we show that contact-resonance atomic force microscopy-which is exquisitely sensitive to stiffness changes that arise from even a single atomic layer of a van der Waals-adhered material-is a powerful experimental tool to address this challenge. A combined density functional theory and continuum modeling approach is introduced that yields sub-surface-sensitive, nanomechanical fingerprints associated with specific, well-defined structure models of individual surface domains. Where such models are known, this information can be correlated with experimentally obtained contact-resonance frequency maps to reveal the (sub)surface structure of different domains on the sample.

Modeling the Hydrologic Response to Changes in Groundcover Conditions Caused by Fire Disturbances

NASA Astrophysics Data System (ADS)

Kikinzon, E.; Atchley, A. L.; Coon, E.; Middleton, R. S.

2016-12-01

Climate change and fire suppression increase wildfire activity, which alters ecosystem functions and can significantly impact hydrological response. Both wildfire and prescribed burns reduce groundcover, affect top layers of subsurface, and change the structure of overland flow pathways. To understand respective effects on surface and subsurface hydrology, it is imperative to accurately represent surface-subsurface interface pre and post-fire, and to model physical processes in groundcover components. We show mechanistic models used to describe physics in two key types of groundcover, litter and duff, in Advanced Terrestrial Simulator (ATS). Litter is considered to be a part of vegetative canopy covering the surface. It has associated water storage capacity, which allows simulating interception and drainage, and its thickness is used to evaluate surface roughness with potential effect of slowing overland flow compared to bare soil. Duff on the other hand is incorporated into the subsurface, thus requiring meshing and discretization capability to support complex geometries including pinchouts, which is necessary both for achieving desired mesh resolution and portraying bare soil patches without adversely affecting the time scale. As part of the subsurface, duff has its own hydrologic and water retention properties used to resolve infiltration and saturation limited runoff generation, run on, and infiltration processes. This enables the use of ATS for fine scale modeling of integrated hydrology with adequate representation of groundcover influence. To isolate the impact of changing groundcover, we consider a simple hill slope and study the hydrological response to varying amount and geometries of groundcover. To cover landscape characteristics produced by a wide variety of fire conditions, from high intensity to low intensity fire impacts, we simulate hydrologic response to precipitation events over a number of typical geometries and with fine control over amounts of two described types of groundcover. We then analyze hydrological sensitivity to presence or absence of particular groundcover types, their respective patchiness, and possible changes in overland flow pathways.

Inverse scattering pre-stack depth imaging and it's comparison to some depth migration methods for imaging rich fault complex structure

NASA Astrophysics Data System (ADS)

Nurhandoko, Bagus Endar B.; Sukmana, Indriani; Mubarok, Syahrul; Deny, Agus; Widowati, Sri; Kurniadi, Rizal

2012-06-01

Migration is important issue for seismic imaging in complex structure. In this decade, depth imaging becomes important tools for producing accurate image in depth imaging instead of time domain imaging. The challenge of depth migration method, however, is in revealing the complex structure of subsurface. There are many methods of depth migration with their advantages and weaknesses. In this paper, we show our propose method of pre-stack depth migration based on time domain inverse scattering wave equation. Hopefully this method can be as solution for imaging complex structure in Indonesia, especially in rich thrusting fault zones. In this research, we develop a recent advance wave equation migration based on time domain inverse scattering wave which use more natural wave propagation using scattering wave. This wave equation pre-stack depth migration use time domain inverse scattering wave equation based on Helmholtz equation. To provide true amplitude recovery, an inverse of divergence procedure and recovering transmission loss are considered of pre-stack migration. Benchmarking the propose inverse scattering pre-stack depth migration with the other migration methods are also presented, i.e.: wave equation pre-stack depth migration, waveequation depth migration, and pre-stack time migration method. This inverse scattering pre-stack depth migration could image successfully the rich fault zone which consist extremely dip and resulting superior quality of seismic image. The image quality of inverse scattering migration is much better than the others migration methods.

Representing spatial and temporal complexity in ecohydrological models: a meta-analysis focusing on groundwater - surface water interactions

NASA Astrophysics Data System (ADS)

McDonald, Karlie; Mika, Sarah; Kolbe, Tamara; Abbott, Ben; Ciocca, Francesco; Marruedo, Amaia; Hannah, David; Schmidt, Christian; Fleckenstein, Jan; Karuse, Stefan

2016-04-01

Sub-surface hydrologic processes are highly dynamic, varying spatially and temporally with strong links to the geomorphology and hydrogeologic properties of an area. This spatial and temporal complexity is a critical regulator of biogeochemical and ecological processes within the interface groundwater - surface water (GW-SW) ecohydrological interface and adjacent ecosystems. Many GW-SW models have attempted to capture this spatial and temporal complexity with varying degrees of success. The incorporation of spatial and temporal complexity within GW-SW model configuration is important to investigate interactions with transient storage and subsurface geology, infiltration and recharge, and mass balance of exchange fluxes at the GW-SW ecohydrological interface. Additionally, characterising spatial and temporal complexity in GW-SW models is essential to derive predictions using realistic environmental conditions. In this paper we conduct a systematic Web of Science meta-analysis of conceptual, hydrodynamic, and reactive and heat transport models of the GW-SW ecohydrological interface since 2004 to explore how these models handled spatial and temporal complexity. The freshwater - groundwater ecohydrological interface was the most commonly represented in publications between 2004 and 2014 with 91% of papers followed by marine 6% and estuarine systems with 3% of papers. Of the GW-SW models published since 2004, the 52% have focused on hydrodynamic processes and <15% covered more than one process (e.g. heat and reactive transport). Within the hydrodynamic subset, 25% of models focused on a vertical depth of <5m. The primary scientific and technological limitations of incorporating spatial and temporal variability into GW-SW models are identified as the inclusion of woody debris, carbon sources, subsurface geological structures and bioclogging into model parameterization. The technological limitations influence the types of models applied, such as hydrostatic coupled models and fully intrinsic saturated and unsaturated models, and the assumptions or simplifications scientists apply to investigate the GW-SW ecohydrological interface. We investigated the type of modelling approaches applied across different scales (site, reach, catchment, nested catchments) and assessed the simplifications in environmental conditions and complexity that are commonly made in model configuration. Understanding the theoretical concepts that underpin these current modelling approaches is critical for scientists to develop measures to derive predictions from realistic environmental conditions at management relevant scales and establish best-practice modelling approaches for improving the scientific understanding and management of the GW-SW interface. Additionally, the assessment of current modelling approaches informs our proposed framework for the progress of GW-SW models in the future. The framework presented aims to increase future scientific, technological and management integration and the identification of research priorities to allow spatial and temporal complexity to be better incorporated into GW-SW models.

SST Control by Subsurface Mixing During Indian Ocean Monsoons

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. SST Control by Subsurface Mixing during Indian Ocean ...quantify the variability in upper ocean mixing associated with changes in barrier layer thickness and strength across the BoB and under different...These objectives directly target the fundamental role that upper ocean dynamics play in the complex air-sea interactions of the northern Indian Ocean

Microbial community structure in a shallow hydrocarbon-contaminated aquifer associated with high electrical conductivity

NASA Astrophysics Data System (ADS)

Duris, J. W.; Rossbach, S.; Atekwana, E. A.; Werkema, D., Jr.

2003-04-01

Little is known about the complex interactions between microbial communities and electrical properties in contaminated aquifers. In order to investigate possible connections between these parameters a study was undertaken to investigate the hypothesis that the degradation of hydrocarbons by resident microbial communities causes a local increase in organic acid concentrations, which in turn cause an increase in native mineral weathering and a concurrent increase in the bulk electrical conductivity of soil. Microbial community structure was analyzed using a 96-well most probable number (MPN) method and rDNA intergenic spacer region analysis (RISA). Microbial community structure was found to change in the presence of hydrocarbon contaminants and these changes were consistently observed in regions of high electrical conductivity. We infer from this relationship that geophysical methods for monitoring the subsurface are a promising new technology for monitoring changes in microbial community structure and simultaneous changes in geochemistry that are associated with hydrocarbon degradation.

Identification and characterization of natural pipe systems in forested tropical soils

NASA Astrophysics Data System (ADS)

Bovi, Renata Cristina; Moreira, Cesar Augusto; Stucchi Boschi, Raquel; Cooper, Miguel

2017-04-01

Erosive processes on soil surface have been well studied and comprehended by several researchers, however little is known about subsurface erosive processes (piping). Piping is a type of subsurface erosion caused by water flowing in the subsurface and is still considered one of the most difficult erosive processes to be studied. Several processes have been considered as resposible for subsurface erosion and their interaction is complex and difficult to be studied separately. Surface investigations on their own may underestimate the erosion processes, due to the possible occurrence of subsurface processes that are not yet exposed on the surface. The network of subsurface processes should also be understood to better control erosion. Conservation practices that focus on water runoff control may be inefficient if the subsurface flow is not considered. In this study, we aimed to identify and characterize subsurface cavities in the field, as well as understand the network of these cavities, by using geophysical methods (electrical tomography). The study area is situated at the Experimental Station of Tupi, state of São Paulo, Brazil. The soil of the area was classified as Hapludults. The area presents several erosive features, ranging from laminar to permanent gullies and subsurface erosions. The geophysical equipment used was the Terrameter LS resistivity meter, manufactured by ABEM Instruments. The method of electrical tomography was efficient to detect collapsed and non-collapsed pipes. The results presented valuable information to detect areas of risk.

Identifying structural styles in Colombia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, W.P.; Van Nieuwenhuise, R.E.; Steuer, M.R.

1996-08-01

Much of our understanding of the Earth is from the study of surface geology and seismic, but many surface structures are responses to deformation which occurred below sedimentary layers. The practice within the petroleum industry is to use top-down processes of analyzing the surface to understand the subsurface, and observed surface structural styles tend to influence seismic interpretations. Yet many conditions which influenced the structural styles seen at the surface are different at depth. Since seismic is a time representation of the Earth, many interpretation pitfalls may exist within areas of complex geology. Also, its reliability decreases with depth andmore » with increasing geologic complexity. Forward modeling and pre-stack depth migration technologies are used to provide true depth images of the seismic data. Even with these advances in seismic imaging technology, the interpreter needs to incorporate additional data into the interpretation. Accurate structural identification requires the interpreter to integrate seismic with surface geology, remote sensing, gravity, magnetic data, geochemistry, fault-plane solutions from earthquakes, and regional tectonic studies. Incorporating these types of data into the interpretation will help us learn how basement is involved in the deformation of overlying sediments. A study of the Eastern Cordillera of Colombia shows the deformation to be dominantly transpressional in style. Euler deconvolution of the areomagnetic data shows a highly fractured basement, steep fault lineaments, en echelon structures, and complex fault patterns, all of which would be typical of wrench-type deformation. Available surface geology, regional studies, earthquake data, and forward modeling support this interpretation.« less

Employing 2D Forward Modeling of Gravity and Magnetic Data to Further Constrain the Magnitude of Extension Recorded by the Caetano Caldera, Nevada

NASA Astrophysics Data System (ADS)

Ritzinger, B. T.; Glen, J. M. G.; Athens, N. D.; Denton, K. M.; Bouligand, C.

2015-12-01

Regionally continuous Cenozoic rocks in the Basin and Range that predate the onset of major mid-Miocene extension provide valuable insight into the sequence of faulting and magnitude of extension. An exceptional example of this is Caetano caldera, located in north-central Nevada, that formed during the eruption of the Caetano Tuff at the Eocene-Oligocene transition. The caldera and associated deposits, as well as conformable caldera-filling sedimentary and volcanic units allow for the reconstruction of post Oligocene extensional faulting. Extensive mapping and geochronologic, geochemical and paleomagnetic analyses have been conducted over the last decade to help further constrain the eruptive and extensional history of the Caetano caldera and associated deposits. Gravity and magnetic data, that highlight contrasts in density and magnetic properties (susceptibility and remanence), respectively, are useful for mapping and modeling structural and lithic discontinuities. By combining existing gravity and aeromagnetic data with newly collected high-resolution gravity data, we are performing detailed potential field modeling to better characterize the subsurface within and surrounding the caldera. Modeling is constrained by published geologic map and cross sections and by new rock properties for these units determined from oriented drill core and hand samples collected from outcrops that span all of the major rock units in the study area. These models will enable us to better map the margins of the caldera and more accurately determine subsurface lithic boundaries and complex fault geometries, as well as aid in refining estimates of the magnitude of extension across the caldera. This work highlights the value in combining geologic and geophysical data to build an integrated structural model to help characterize the subsurface and better constrain the extensional tectonic history if this part of the Great Basin.

Extraction of Seabed/Subsurface Features in a Potential CO2 Sequestration Site in the Southern Baltic Sea, Using Wavelet Transform of High-resolution Sub-Bottom Profiler Data

NASA Astrophysics Data System (ADS)

Tegowski, J.; Zajfert, G.

2014-12-01

Carbon Capture & Storage (CCS) efficiently prevents the release of anthropogenic CO2 into the atmosphere. We investigate a potential site in the Polish Sector of the Baltic Sea (B3 field site), consisting in a depleted oil and gas reservoir. An area ca. 30 x 8 km was surveyed along 138 acoustic transects, realised from R/V St. Barbara in 2012 and combining multibeam echosounder, sidescan sonar and sub-bottom profiler. Preparation of CCS sites requires accurate knowledge of the subsurface structure of the seafloor, in particular deposit compactness. Gas leaks in the water column were monitored, along with the structure of upper sediment layers. Our analyses show the shallow sub-seabed is layered, and quantified the spatial distribution of gas diffusion chimneys and seabed effusion craters. Remote detection of gas-containing surface sediments can be rather complex if bubbles are not emitted directly into the overlying water and thus detectable acoustically. The heterogeneity of gassy sediments makes conventional bottom sampling methods inefficient. Therefore, we propose a new approach to identification, mapping, and monitoring of potentially gassy surface sediments, based on wavelet analysis of echo signal envelopes of a chirp sub-bottom profiler (EdgeTech SB-0512). Each echo envelope was subjected to wavelet transformation, whose coefficients were used to calculate wavelet energies. The set of echo envelope parameters was input to fuzzy logic and c-means algorithms. The resulting classification highlights seafloor areas with different subsurface morphological features, which can indicate gassy sediments. This work has been conducted under EC FP7-CP-IP project No. 265847: Sub-seabed CO2 Storage: Impact on Marine Ecosystems (ECO2).

Seismoelectric Effects based on Spectral-Element Method for Subsurface Fluid Characterization

NASA Astrophysics Data System (ADS)

Morency, C.

2017-12-01

Present approaches for subsurface imaging rely predominantly on seismic techniques, which alone do not capture fluid properties and related mechanisms. On the other hand, electromagnetic (EM) measurements add constraints on the fluid phase through electrical conductivity and permeability, but EM signals alone do not offer information of the solid structural properties. In the recent years, there have been many efforts to combine both seismic and EM data for exploration geophysics. The most popular approach is based on joint inversion of seismic and EM data, as decoupled phenomena, missing out the coupled nature of seismic and EM phenomena such as seismoeletric effects. Seismoelectric effects are related to pore fluid movements with respect to the solid grains. By analyzing coupled poroelastic seismic and EM signals, one can capture a pore scale behavior and access both structural and fluid properties.Here, we model the seismoelectric response by solving the governing equations derived by Pride and Garambois (1994), which correspond to Biot's poroelastic wave equations and Maxwell's electromagnetic wave equations coupled electrokinetically. We will show that these coupled wave equations can be numerically implemented by taking advantage of viscoelastic-electromagnetic mathematical equivalences. These equations will be solved using a spectral-element method (SEM). The SEM, in contrast to finite-element methods (FEM) uses high degree Lagrange polynomials. Not only does this allow the technique to handle complex geometries similarly to FEM, but it also retains exponential convergence and accuracy due to the use of high degree polynomials. Finally, we will discuss how this is a first step toward full coupled seismic-EM inversion to improve subsurface fluid characterization. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Radar soundings of the ionosphere of Mars.

PubMed

Gurnett, D A; Kirchner, D L; Huff, R L; Morgan, D D; Persoon, A M; Averkamp, T F; Duru, F; Nielsen, E; Safaeinili, A; Plaut, J J; Picardi, G

2005-12-23

We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere to a wide variety of oblique and diffuse echoes. The oblique echoes are believed to arise mainly from ionospheric structures associated with the complex crustal magnetic fields of Mars. Echoes at the electron plasma frequency and the cyclotron period also provide measurements of the local electron density and magnetic field strength.

Global Nonlinear Optimization for the Interpretation of Magnetic Anomalies Over Idealized Geological Bodies for Ore Exploration - An Insight about Uncertainty

NASA Astrophysics Data System (ADS)

Biswas, A.

2016-12-01

A Very Fast Simulated Annealing (VFSA) global optimization code is produced for elucidation of magnetic data over various idealized bodies for mineral investigation. The way of uncertainty in the interpretation is additionally analyzed in the present study. This strategy fits the watched information exceptionally well by some straightforward geometrically body in the confined class of Sphere, horizontal cylinder, thin dyke and sheet type models. The consequences of VFSA improvement uncover that different parameters demonstrate various identical arrangements when state of the objective body is not known and shape factor "q" is additionally advanced together with other model parameters. The study uncovers that amplitude coefficient k is firmly subject to shape factor. This demonstrates there is multi-model sort vulnerability between these two model parameters. Be that as it may, the assessed estimations of shape factor from different VFSA runs without a doubt show whether the subsurface structure is sphere, horizontal cylinder, and dyke or sheet type structure. Thus, the precise shape element (2.5 for sphere, 2.0 for horizontal cylinder and 1.0 for dyke and sheet) is settled and improvement procedure is rehashed. Next, altering the shape factor and investigation of uncertainty as well as scatter-plots demonstrates a very much characterized uni-model characteristics. The mean model figured in the wake of settling the shape factor gives the highest dependable results. Inversion of noise-free and noisy synthetic data information and additionally field information shows the adequacy of the methodology. The procedure has been carefully and practically connected to five genuine field cases with the nearness of mineralized bodies covered at various profundities in the subsurface and complex geological settings. The method can be to a great degree appropriate for mineral investigation, where the attractive information is seen because of mineral body established in the shallow/deeper subsurface and the calculation time for the entire procedure are short. Keywords: Magnetic anomaly, idealized body, uncertainty, VFSA, multiple structure, ore exploration.

[Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

PubMed

Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

2014-02-01

The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

Subsurface structures of the active reverse fault zones in Japan inferred from gravity anomalies.

NASA Astrophysics Data System (ADS)

Matsumoto, N.; Sawada, A.; Hiramatsu, Y.; Okada, S.; Tanaka, T.; Honda, R.

2016-12-01

The object of our study is to examine subsurface features such as continuity, segmentation and faulting type, of the active reverse fault zones. We use the gravity data published by the Gravity Research Group in Southwest Japan (2001), the Geographical Survey Institute (2006), Yamamoto et al. (2011), Honda et al. (2012), and the Geological Survey of Japan, AIST (2013) in this study. We obtained the Bouguer anomalies through terrain corrections with 10 m DEM (Sawada et al. 2015) under the assumed density of 2670 kg/m3, a band-pass filtering, and removal of linear trend. Several derivatives and structural parameters calculated from a gravity gradient tensor are applied to highlight the features, such as a first horizontal derivatives (HD), a first vertical derivatives (VD), a normalized total horizontal derivative (TDX), a dip angle (β), and a dimensionality index (Di). We analyzed 43 reverse fault zones in northeast Japan and the northern part of southwest Japan among major active fault zones selected by Headquarters for Earthquake Research Promotion. As the results, the subsurface structural boundaries clearly appear along the faults at 21 faults zones. The weak correlations appear at 13 fault zones, and no correlations are recognized at 9 fault zones. For example, in the Itoigawa-Shizuoka tectonic line, the subsurface structure boundary seems to extend further north than the surface trace. Also, a left stepping structure of the fault around Hakuba is more clearly observed with HD. The subsurface structures, which detected as the higher values of HD, are distributed on the east side of the surface rupture in the north segments and on the west side in the south segments, indicating a change of the dip direction, the east dipping to the west dipping, from north to south. In the Yokote basin fault zone, the subsurface structural boundary are clearly detected with HD, VD and TDX along the fault zone in the north segment, but less clearly in the south segment. Also, Di implies the existence of 3D-like structure with E-W trend around the segment boundary. The distribution of dip angle β along the fault zone implies a reverse faulting, corresponding to the faulting type of this fault zone reported by previous studies.

Determining the 3D Subsurface Density Structure of Taurus Littrow Valley Using Apollo 17 Gravity Data

NASA Technical Reports Server (NTRS)

Urbancic, N.; Ghent, R.; Stanley, S,; Johnson, C. L.; Carroll, K. A.; Hatch, D.; Williamson, M. C.; Garry, W. B.; Talwani, M.

2016-01-01

Surface gravity surveys can detect subsurface density variations that can reveal subsurface geologic features. In 1972, the Apollo 17 (A17) mission conducted the Traverse Gravimeter Experiment (TGE) using a gravimeter that measured the local gravity field near Taurus Littrow Valley (TLV), located on the south-eastern rim of the Serenitatis basin. TLV is hypothesized to be a basaltfilled radial graben resulting from the impact that formed Mare Serenitatis. It is bounded by both the North and South Massifs (NM and SM) as well as other smaller mountains to the East that are thought to be mainly composed of brecciated highland material. The TGE is the first and only successful gravity survey on the surface of the Moon. Other more recent satellite surveys, such as NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission (2011- 2012), have produced the best global gravity field to date (approx. 13km resolution). However, these satellite surveys are not sensitive enough to detect fine-scale (<1km) lunar subsurface structures. This underscores the value of the data collected at the surface by A17. In the original analysis of the data a 2D forward-modelling approach was used to derive a thickness of the subsurface basalt layer of 1.0 km by assuming a simple flat-faced rectangular geometry and using densities derived from Apollo lunar samples. We are investigating whether modern 3D modelling techniques in combination with high-resolution topographical and image datasets can reveal additional fine-scale subsurface structure in TLV.

Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) after nine years of operation: A summary

NASA Astrophysics Data System (ADS)

Orosei, R.; Jordan, R. L.; Morgan, D. D.; Cartacci, M.; Cicchetti, A.; Duru, F.; Gurnett, D. A.; Heggy, E.; Kirchner, D. L.; Noschese, R.; Kofman, W.; Masdea, A.; Plaut, J. J.; Seu, R.; Watters, T. R.; Picardi, G.

2015-07-01

Mars Express, the first European interplanetary mission, carries the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to search for ice and water in the Martian subsurface. Developed by an Italian-US team, MARSIS transmits low-frequency, wide-band radio pulses penetrating below the surface and reflected by dielectric discontinuities linked to structural or compositional changes. MARSIS is also a topside ionosphere sounder, transmitting a burst of short, narrow-band pulses at different frequencies that are reflected by plasma with varying densities at different altitudes. The radar operates since July 2005, after the successful deployment of its 40 m antenna, acquiring data at altitudes lower than 1200 km. Subsurface sounding (SS) data are processed on board by stacking together a batch of echoes acquired at the same frequency. On ground, SS data are further processed by correlating the received echo with the transmitted waveform and compensating de-focusing caused by the dispersive ionosphere. Ground processing of active ionospheric sounding (AIS) data consists in the reconstruction of the electron density profile as a function of altitude. MARSIS observed the internal structure of Planum Boreum outlining the Basal Unit, an icy deposit lying beneath the North Polar Layered Deposits thought to have formed in an epoch in which climate was markedly different from the current one. The total volume of ice in polar layered deposits could be estimated, and parts of the Southern residual ice cap were revealed to consist of ≈ 10 m of CO2 ice. Radar properties of the Vastitas Borealis Formation point to the presence of large quantities of ice buried beneath the surface. Observations of the ionosphere revealed the complex interplay between plasma, crustal magnetic field and solar wind, contributing to space weather studies at Mars. The presence of three-dimensional plasma structures in the ionosphere was revealed for the first time. MARSIS could successfully operate at Phobos, becoming the first instrument of its kind to observe an asteroid-like body. The main goal pursued by MARSIS, the search for liquid water beneath the surface, remains elusive. However, because of the many factors affecting detection and of the difficulties in identifying water in radar echoes, a definitive conclusion on its presence cannot yet be drawn.

The advantages of complementing MT profiles in 3-D environments with geomagnetic transfer function and interstation horizontal magnetic transfer function data: results from a synthetic case study

NASA Astrophysics Data System (ADS)

Campanyà, Joan; Ogaya, Xènia; Jones, Alan G.; Rath, Volker; Vozar, Jan; Meqbel, Naser

2016-12-01

As a consequence of measuring time variations of the electric and the magnetic field, which are related to current flow and charge distribution, magnetotelluric (MT) data in 2-D and 3-D environments are not only sensitive to the geoelectrical structures below the measuring points but also to any lateral anomalies surrounding the acquisition site. This behaviour complicates the characterization of the electrical resistivity distribution of the subsurface, particularly in complex areas. In this manuscript we assess the main advantages of complementing the standard MT impedance tensor (Z) data with interstation horizontal magnetic tensor (H) and geomagnetic transfer function (T) data in constraining the subsurface in a 3-D environment beneath a MT profile. Our analysis was performed using synthetic responses with added normally distributed and scattered random noise. The sensitivity of each type of data to different resistivity anomalies was evaluated, showing that the degree to which each site and each period is affected by the same anomaly depends on the type of data. A dimensionality analysis, using Z, H and T data, identified the presence of the 3-D anomalies close to the profile, suggesting a 3-D approach for recovering the electrical resistivity values of the subsurface. Finally, the capacity for recovering the geoelectrical structures of the subsurface was evaluated by performing joint inversion using different data combinations, quantifying the differences between the true synthetic model and the models from inversion process. Four main improvements were observed when performing joint inversion of Z, H and T data: (1) superior precision and accuracy at characterizing the electrical resistivity values of the anomalies below and outside the profile; (2) the potential to recover high electrical resistivity anomalies that are poorly recovered using Z data alone; (3) improvement in the characterization of the bottom and lateral boundaries of the anomalies with low electrical resistivity; and (4) superior imaging of the horizontal continuity of structures with low electrical resistivity. These advantages offer new opportunities for the MT method by making the results from a MT profile in a 3-D environment more convincing, supporting the possibility of high-resolution studies in 3-D areas without expending a large amount of economical and computational resources, and also offering better resolution of targets with high electrical resistivity.

Coupling LaGrit unstructured mesh generation and model setup with TOUGH2 flow and transport: A case study

DOE PAGES

Sentis, Manuel Lorenzo; Gable, Carl W.

2017-06-15

Furthermore, there are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools willmore » provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. Here in this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.« less

Geologic structure of the Yucaipa area inferred from gravity data, San Bernardino and Riverside Counties, California

USGS Publications Warehouse

Mendez, Gregory O.; Langenheim, V.E.; Morita, Andrew; Danskin, Wesley R.

2016-09-30

In the spring of 2009, the U.S. Geological Survey, in cooperation with the San Bernardino Valley Municipal Water District, began working on a gravity survey in the Yucaipa area to explore the three-dimensional shape of the sedimentary fill (alluvial deposits) and the surface of the underlying crystalline basement rocks. As water use has increased in pace with rapid urbanization, water managers have need for better information about the subsurface geometry and the boundaries of groundwater subbasins in the Yucaipa area. The large density contrast between alluvial deposits and the crystalline basement complex permits using modeling of gravity data to estimate the thickness of alluvial deposits. The bottom of the alluvial deposits is considered to be the top of crystalline basement rocks. The gravity data, integrated with geologic information from surface outcrops and 51 subsurface borings (15 of which penetrated basement rock), indicated a complex basin configuration where steep slopes coincide with mapped faults―such as the Crafton Hills Fault and the eastern section of the Banning Fault―and concealed ridges separate hydrologically defined subbasins.Gravity measurements and well logs were the primary data sets used to define the thickness and structure of the groundwater basin. Gravity measurements were collected at 256 new locations along profiles that totaled approximately 104.6 km (65 mi) in length; these data supplemented previously collected gravity measurements. Gravity data were reduced to isostatic anomalies and separated into an anomaly field representing the valley fill. The ‘valley-fill-deposits gravity anomaly’ was converted to thickness by using an assumed, depth-varying density contrast between the alluvial deposits and the underlying bedrock.To help visualize the basin geometry, an animation of the elevation of the top of the basement-rocks was prepared. The animation “flies over” the Yucaipa groundwater basin, viewing the land surface, geology, faults, and ridges and valleys of the shaded-relief elevation of the top of the basement complex.

Coupling LaGrit unstructured mesh generation and model setup with TOUGH2 flow and transport: A case study

NASA Astrophysics Data System (ADS)

Sentís, Manuel Lorenzo; Gable, Carl W.

2017-11-01

There are many applications in science and engineering modeling where an accurate representation of a complex model geometry in the form of a mesh is important. In applications of flow and transport in subsurface porous media, this is manifest in models that must capture complex geologic stratigraphy, structure (faults, folds, erosion, deposition) and infrastructure (tunnels, boreholes, excavations). Model setup, defined as the activities of geometry definition, mesh generation (creation, optimization, modification, refine, de-refine, smooth), assigning material properties, initial conditions and boundary conditions requires specialized software tools to automate and streamline the process. In addition, some model setup tools will provide more utility if they are designed to interface with and meet the needs of a particular flow and transport software suite. A control volume discretization that uses a two point flux approximation is for example most accurate when the underlying control volumes are 2D or 3D Voronoi tessellations. In this paper we will present the coupling of LaGriT, a mesh generation and model setup software suite and TOUGH2 (Pruess et al., 1999) to model subsurface flow problems and we show an example of how LaGriT can be used as a model setup tool for the generation of a Voronoi mesh for the simulation program TOUGH2. To generate the MESH file for TOUGH2 from the LaGriT output a standalone module Lagrit2Tough2 was developed, which is presented here and will be included in a future release of LaGriT. In this paper an alternative method to generate a Voronoi mesh for TOUGH2 with LaGriT is presented and thanks to the modular and command based structure of LaGriT this method is well suited to generating a mesh for complex models.

Continuous monitoring of the lunar or Martian subsurface using on-board pattern recognition and neural processing of Rover geophysical data

NASA Technical Reports Server (NTRS)

Mcgill, J. W.; Glass, C. E.; Sternberg, B. K.

1990-01-01

The ultimate goal is to create an extraterrestrial unmanned system for subsurface mapping and exploration. Neural networks are to be used to recognize anomalies in the profiles that correspond to potentially exploitable subsurface features. The ground penetrating radar (GPR) techniques are likewise identical. Hence, the preliminary research focus on GPR systems will be directly applicable to seismic systems once such systems can be designed for continuous operation. The original GPR profile may be very complex due to electrical behavior of the background, targets, and antennas, much as the seismic record is made complex by multiple reflections, ghosting, and ringing. Because the format of the GPR data is similar to the format of seismic data, seismic processing software may be applied to GPR data to help enhance the data. A neural network may then be trained to more accurately identify anomalies from the processed record than from the original record.

Assessment of DInSAR Potential in Simulating Geological Subsurface Structure

NASA Astrophysics Data System (ADS)

Fouladi Moghaddam, N.; Rudiger, C.; Samsonov, S. V.; Hall, M.; Walker, J. P.; Camporese, M.

2013-12-01

High resolution geophysical surveys, including seismic, gravity, magnetic, etc., provide valuable information about subsurface structuring but they are very costly and time consuming with non-unique and sometimes conflicting interpretations. Several recent studies have examined the application of DInSAR to estimate surface deformation, monitor possible fault reactivation and constrain reservoir dynamic behaviour in geothermal and groundwater fields. The main focus of these studies was to generate an elevation map, which represents the reservoir extraction induced deformation. This research study, however, will focus on developing methods to simulate subsurface structuring and identify hidden faults/hydraulic barriers using DInSAR surface observations, as an innovative and cost-effective reconnaissance exploration tool for planning of seismic acquisition surveys in geothermal and Carbon Capture and Sequestration regions. By direct integration of various DInSAR datasets with overlapping temporal and spatial coverage we produce multi-temporal ground deformation maps with high resolution and precision to evaluate the potential of a new multidimensional MSBAS technique (Samsonov & d'Oreye, 2012). The technique is based on the Small Baseline Subset Algorithm (SBAS) that is modified to account for variation in sensor parameters. It allows integration of data from sensors with different wave-band, azimuth and incidence angles, different spatial and temporal sampling and resolutions. These deformation maps then will be used as an input for inverse modelling to simulate strain history and shallow depth structure. To achieve the main objective of our research, i.e. developing a method for coupled InSAR and geophysical observations and better understanding of subsurface structuring, comparing DInSAR inverse modelling results with previously provided static structural model will result in iteratively modified DInSAR structural model for adequate match with in situ observations. The newly developed and modified algorithm will then be applied in another part of the region where subsurface information is limited.

Influence of bedrock topography on the runoff generation under use of ERT data

NASA Astrophysics Data System (ADS)

Kiese, Nina; Loritz, Ralf; Allroggen, Niklas; Zehe, Erwin

2017-04-01

Subsurface topography has been identified to play a major role for the runoff generation in different hydrological landscapes. Sinks and ridges in the bedrock can control how water is stored and transported to the stream. Detecting the subsurface structure is difficult and laborious and frequently done by auger measurements. Recently, the geophysical imaging of the subsurface by Electrical Resistivity Tomography (ERT) gained much interest in the field of hydrology, as it is a non-invasive method to collect information on the subsurface characteristics and particularly bedrock topography. As it is impossible to characterize the subsurface of an entire hydrological landscape using ERT, it is of key interest to identify the bedrock characteristics which dominate runoff generation to adapt and optimize the sampling design to the question of interest. For this study, we used 2D ERT images and auger measurements, collected on different sites in the Attert basin in Luxembourg, to characterize bedrock topography using geostatistics and shed light on those aspects which dominate runoff generation. Based on ERT images, we generated stochastic bedrock topographies and implemented them in a physically-based 2D hillslope model. With this approach, we were able to test the influence of different subsurface structures on the runoff generation. Our results highlight that ERT images can be useful for hydrological modelling. Especially the connection from the hillslope to the stream could be identified as important feature in the subsurface for the runoff generation whereas the microtopography of the bedrock seemed to be less relevant.

Subsurface Hydrology: Data Integration for Properties and Processes

NASA Astrophysics Data System (ADS)

Hyndman, David W.; Day-Lewis, Frederick D.; Singha, Kamini

Groundwater is a critical resource and the PrinciPal source of drinking water for over 1.5 billion people. In 2001, the National Research Council cited as a "grand challenge" our need to understand the processes that control water movement in the subsurface. This volume faces that challenge in terms of data integration between complex, multi-scale hydrologie processes, and their links to other physical, chemical, and biological processes at multiple scales. Subsurface Hydrology: Data Integration for Properties and Processes presents the current state of the science in four aspects: • Approaches to hydrologie data integration • Data integration for characterization of hydrologie properties • Data integration for understanding hydrologie processes • Meta-analysis of current interpretations Scientists and researchers in the field, the laboratory, and the classroom will find this work an important resource in advancing our understanding of subsurface water movement.

Lateral, vertical, and longitudinal connectivity of runoff source areas drive stream hydro-biogeochemical signals across a low relief drainage network

NASA Astrophysics Data System (ADS)

Zimmer, M. A.; McGlynn, B. L.

2017-12-01

Our understanding of the balance between longitudinal, lateral, and vertical expansion and contraction of reactive flowpaths and source areas in headwater catchments is limited. To address this, we utilized an ephemeral-to-perennial stream network in the Piedmont region of North Carolina, USA to gain new understanding about critical zone mechanisms that drive runoff generation and biogeochemical signals in both groundwater and stream water. Here, we used chemical and hydrometric data collected from zero through second order catchments to characterize spatial and temporal runoff and overland, shallow soil, and deep subsurface flow across characteristic landscape positions. Our results showed that the active stream network was driven by two superimposed runoff generation regimes that produced distinct hydro-biogeochemical signals at the catchment outlet. The baseflow runoff generation regime expanded and contracted the stream network seasonally through the rise and fall of the seasonal water table. Superimposed on this, event-activated source area contributions were driven by surficial and shallow subsurface flowpaths. The subsurface critical zone stratigraphy in this landscape coupled with the precipitation regime activated these shallow flowpaths frequently. This drove an increase in dissolved organic carbon (DOC) concentrations with increases in runoff across catchment scales. DOC-runoff relationship variability and spread was driven by the balance between runoff regimes as well as a seasonal depletion of DOC from shallow subsurface flowpath activation and annual replenishment from litterfall. From this, we suggest that the hydro-biogeochemical signals at larger catchment outlets can be driven by a balance of longitudinal, lateral, and vertical source area contributions, critical zone structure, and complex hydrological processes.

Dynamics of nonreactive solute transport in the permafrost environment

NASA Astrophysics Data System (ADS)

Svyatskiy, D.; Coon, E. T.; Moulton, J. D.

2017-12-01

As part of the DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic, researchers are developing process-rich models to understand and predict the evolution of water sources and hydrologic flow pathways resulting from degrading permafrost. The sources and interaction of surface and subsurface water and flow paths are complex in space and time due to strong interplay between heterogeneous subsurface parameters, the seasonal to decadal evolution of the flow domain, climate driven melting and release of permafrost ice as a liquid water source, evolving surface topography and highly variable meteorological data. In this study, we seek to characterize the magnitude of vertical and lateral subsurface flows in a cold, wet tundra, polygonal landscape characteristic of the Barrow Peninsula, AK. To better understand the factors controlling water flux partitioning in these low gradient landscapes, NGEE researchers developed and are applying the Advanced Terrestrial Simulator (ATS), which fully couples surface and subsurface flow and energy processes, snow distribution and atmospheric forcing. Here we demonstrate the integration of a new solute transport model within the ATS, which enables the interpretation of applied and natural tracer experiments and observations aimed at quantifying water sources and flux partitioning. We examine the role of ice wedge polygon structure, freeze-thaw processes and soil properties on the seasonal transport of water within and through polygons features, and compare results to tracer experiments on 2D low-centered and high-centered transects corresponding to artificial as well as realistic topographical data from sites in polygonal tundra. These simulations demonstrate significant difference between flow patterns between permafrost and non-permafrost environments due to active layer freeze-thaw processes.

Using Downhole Probes to Locate and Characterize Buried Transuranic and Mixed Low Level Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinman, Donald K; Bramblett, Richard L; Hertzog, Russel C

2012-06-25

Borehole logging probes were developed and tested to locate and quantify transuranic elements in subsurface disposal areas and in contaminated sites at USDOE Weapons Complex sites. A new method of measuring very high levels of chlroine in the subsurface was developed using pulsed neutron technology from oilfield applications. The probes were demonstrated at the Hanford site in wells containing plutonium and other contaminants.

Guidelines for the design of subsurface drainage systems for highway structural sections

DOT National Transportation Integrated Search

1972-06-01

Design criteria and a design method for pavement subsurface drainage systems include inflow-outflow method of analysis, open graded drainage layers, collector drains, pipe outlets and markers. Design examples are given for embankment sections, cut se...

Active Region Formation and Subsurface Structure

NASA Astrophysics Data System (ADS)

Stein, F.; Nordlund, Robert A.

2016-10-01

We present results from emerging magnetic flux simulations showing how several different active regions form and their very different subsurface structures. The simulations assumed an infinite sheet of uniform, untwisted, horizontal field advected into the computational domain by inflows at a depth of 20 Mm. Results from two different horizontal field strengths, 1 and 5 kG, will be presented. Convective up and down flows buckle the horizontal field into Omega and U loops. Upflows and magnetic buoyancy carry the field toward the surface, while fast downflows pin down the field. Small (granular) convective motions, near the surface, shred the emerging field into fine filaments that emerge as the observed "pepper and salt" pattern. The large (supergranular) motions, at depth, keep the overall loop structure intact, so that as the overall omega-loop emerges through the surface the opposite polarity fields counter-stream into large unipolar flux concentrations producing first pores which then coalesce into spots. These tend to be located over the supergranular downflow lanes near the bottom of the domain. The pores and spots exhibit a great variety of subsurface field structures - from monolithic but twisted bundles to intertwined separate spaghetti sturctures. We will show movies of the surface evolution of the field and emergent continuum intensity and of the subsurface evolution of the magnetic field lines.

In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface.

PubMed

Müller, Katharina; Gröschel, Annett; Rossberg, André; Bok, Frank; Franzen, Carola; Brendler, Vinzenz; Foerstendorf, Harald

2015-02-17

Hematite plays a decisive role in regulating the mobility of contaminants in rocks and soils. The Np(V) reactions at the hematite-water interface were comprehensively investigated by a combined approach of in situ vibrational spectroscopy, X-ray absorption spectroscopy and surface complexation modeling. A variety of sorption parameters such as Np(V) concentration, pH, ionic strength, and the presence of bicarbonate was considered. Time-resolved IR spectroscopic sorption experiments at the iron oxide-water interface evidenced the formation of a single monomer Np(V) inner-sphere sorption complex. EXAFS provided complementary information on bidentate edge-sharing coordination. In the presence of atmospherically derived bicarbonate the formation of the bis-carbonato inner-sphere complex was confirmed supporting previous EXAFS findings.1 The obtained molecular structure allows more reliable surface complexation modeling of recent and future macroscopic data. Such confident modeling is mandatory for evaluating water contamination and for predicting the fate and migration of radioactive contaminants in the subsurface environment as it might occur in the vicinity of a radioactive waste repository or a reprocessing plant.

Adsorption of uranium(VI) to manganese oxides: X-ray absorption spectroscopy and surface complexation modeling.

PubMed

Wang, Zimeng; Lee, Sung-Woo; Catalano, Jeffrey G; Lezama-Pacheco, Juan S; Bargar, John R; Tebo, Bradley M; Giammar, Daniel E

2013-01-15

The mobility of hexavalent uranium in soil and groundwater is strongly governed by adsorption to mineral surfaces. As strong naturally occurring adsorbents, manganese oxides may significantly influence the fate and transport of uranium. Models for U(VI) adsorption over a broad range of chemical conditions can improve predictive capabilities for uranium transport in the subsurface. This study integrated batch experiments of U(VI) adsorption to synthetic and biogenic MnO(2), surface complexation modeling, ζ-potential analysis, and molecular-scale characterization of adsorbed U(VI) with extended X-ray absorption fine structure (EXAFS) spectroscopy. The surface complexation model included inner-sphere monodentate and bidentate surface complexes and a ternary uranyl-carbonato surface complex, which was consistent with the EXAFS analysis. The model could successfully simulate adsorption results over a broad range of pH and dissolved inorganic carbon concentrations. U(VI) adsorption to synthetic δ-MnO(2) appears to be stronger than to biogenic MnO(2), and the differences in adsorption affinity and capacity are not associated with any substantial difference in U(VI) coordination.

Geomorphic factors related to the persistence of subsurface oil from the Exxon Valdez oil spill

USGS Publications Warehouse

Nixon, Zachary; Michel, Jacqueline; Hayes, Miles O.; Irvine, Gail V.; Short, Jeffrey

2013-01-01

Oil from the 1989 Exxon Valdez oil spill has persisted along shorelines of Prince William Sound, Alaska, for more than two decades as both surface and subsurface oil residues. To better understand the distribution of persistent subsurface oil and assess the potential need for further restoration, a thorough and quantitative understanding of the geomorphic factors controlling the presence or absence of subsurface oil is required. Data on oiling and geomorphic features were collected at 198 sites in Prince William Sound to identify and quantify the relationships among these geomorphic factors and the presence and absence of persistent subsurface oil. Geomorphic factors associated with the presence of subsurface oil were initial oil exposure, substrate permeability, topographic slope, low exposure to waves, armoring on gravel beaches, tombolos, natural breakwaters, and rubble accumulations. Geomorphic factors associated with the absence of subsurface oil were impermeable bedrock; platforms with thin sediment veneer; fine-grained, well-sorted gravel beaches with no armor; and low-permeability, raised bay-bottom beaches. Relationships were found between the geomorphic and physical site characteristics and the likelihood of encountering persistent subsurface oiling at those sites. There is quantitative evidence of more complex interactions between the overall wave energy incident at a site and the presence of fine-scale geomorphic features that may have provided smaller, local wave energy sheltering of oil. Similarly, these data provide evidence for interactions between the shoreline slope and the presence of angular rubble, with decreased likelihood for encountering subsurface oil at steeply sloped sites except at high-angle sheltered rubble shoreline locations. These results reinforce the idea that the interactions of beach permeability, stability, and site-specific wave exposure are key drivers for subsurface oil persistence in exposed and intermittently exposed mixed gravel beach and rocky shoreline environments.

Hydrology of vernal pools at three sites, southern Sacramento Valley

DOT National Transportation Integrated Search

2005-04-01

The subsurface hydrology of vernal pools at three vernal pool complexes was investigated during three wet seasons in 2002- : 2004. The complexes were at Gridley Ranch, Valensin Ranch, and the Mather Field in northern California. The selected : comple...

Probing the surface of γ-Al2O3 by oxygen-17 dynamic nuclear polarization enhanced solid-state NMR spectroscopy.

PubMed

Li, Wenzheng; Wang, Qiang; Xu, Jun; Aussenac, Fabien; Qi, Guodong; Zhao, Xingling; Gao, Pan; Wang, Chao; Deng, Feng

2018-06-14

γ-Al2O3 is an important catalyst and catalyst support of industrial interest. Its acid/base characteristics are correlated to the surface structure, which has always been an issue of concern. In this work, the complex (sub-)surface oxygen species on surface-selectively labelled γ-Al2O3 were probed by 17O dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP-SENS). Direct 17O MAS and indirect 1H-17O cross-polarization (CP)/MAS DNP experiments enable observation of the (sub-)surface bare oxygen species and hydroxyl groups. In particular, a two-dimensional (2D) 17O 3QMAS DNP spectrum was for the first time achieved for γ-Al2O3, in which two O(Al)4 and one O(Al)3 bare oxygen species were identified. The 17O isotropic chemical shifts (δcs) vary from 56.7 to 81.0 ppm and the quadrupolar coupling constants (CQ) range from 0.6 to 2.5 MHz for the three oxygen species. The coordinatively unsaturated O(Al)3 species is characterized by a higher field chemical shift (56.7 ppm) and the largest CQ value (2.5 MHz) among these oxygen sites. 2D 1H → 17O HETCOR DNP experiments allow us to discriminate three bridging (Aln)-μ2-OH and two terminal (Aln)-μ1-OH hydroxyl groups. The structural features of the bare oxygen species and hydroxyl groups are similar for the γ-Al2O3 samples isotopically labelled by 17O2 gas or H217O. The results presented here show that the combination of surface-selective labelling and DNP-SENS is an effective approach for characterizing oxides with complex surface species.

The stratigraphic record of Khawr Al Maqta, Abu Dhabi, United Arab Emirates

NASA Astrophysics Data System (ADS)

Lokier, S. W.; Herrmann, S.

2012-04-01

Well-constrained modern depositional analogues are vital to the development of accurate geological reservoir models. The development of realistic hydrocarbon reservoir models requires the application of high-precision, well-constrained outcrop and sub-surface data sets with accurately-documented facies geometries and depositional sequence architectures. The Abu Dhabi coastline provides the best modern analogue for the study of ramp-style carbonate depositional facies akin to those observed in the sub-surface reservoirs of the United Arab Emirates (UAE). However, all previous studies have relied on temporally limited surface datasets. This study employed thirty five shallow subsurface cores spanning the width of the Khawr Al Maqta - the narrow shallow tidal channel that separates Abu Dhabi Island from the mainland. The cores were taken over a transect measuring 1.2 km in length by 50 m wide thus providing a high-resolution record of sub-surface facies geometries in a stratigraphically complex setting. Geometries in these Pleistocene to Holocene facies are complex with interdigitating, laterally heterogeneous carbonate, siliciclastic and evaporite units represented throughout the area of the study. Carbonate facies range from molluscan rudstones to marls and are all indicative of deposition in a shallow, relatively low energy marine setting akin to that seen in the environs of Abu Dhabi Island today. Texturally mature quartz sands occur as thin lenses and as thin cross bedded or laminated horizons up to twenty five centimetres thick. Glauconitic mudstones are common and locally exhibit evidence of rootlets and desiccation cracks. Evaporites are present in the form of gypsum occurring as isolated crystals and nodules or as massive chicken-wire units in excess of three metres thick. All of these textures are consistent with evaporite development in the shallow subsurface. Early, shallow-burial diagenesis has been important. Bioclasts are pervasively leached throughout the stratigraphic sequence thereby resulting in a significant enhancement in porosity in the carbonate lithologies. This pervasive mouldic porosity is locally occluded by the precipitation of gypsum cements. The displacive precipitation of significant quantities of gypsum has resulted in the deformation of primary sedimentary structures. This complex sequence of mixed carbonate-siliciclastic-evaporite lithofacies is interpreted to record repeated episodes of flooding and sub-aerial exposure associated with the waxing and waning of the Pleistocene ice-sheets. During periods of relative sea-level fall carbonate sequences entered the meteoric realm with the consequent dissolution of unstable bioclasts. Transgression and reflooding once again isolated Abu Dhabi Island from the mainland, thus permitting the precipitation of shallow-water carbonate lithofacies. During sea-level highstands the north-westerly Shamal wind transported carbonate sediments into the lee-of the island resulting in the south-easterly shore-wards development of a tombolo. However, the strong tidal currents of the Khawr Al Maqta prevented final connection to the mainland, thus ensuring the isolation of Abu Dhabi until the subsequent regression.

Optimal Electromagnetic (EM) Geophysical Techniques to Map the Concentration of Subsurface Ice and Adsorbed Water on Mars and the Moon

NASA Astrophysics Data System (ADS)

Stillman, D. E.; Grimm, R. E.

2013-12-01

Water ice is ubiquitous in our Solar System and is a probable target for planetary exploration. Mapping the lateral and vertical concentration of subsurface ice from or near the surface could determine the origin of lunar and martian ice and quantify a much-needed resource for human exploration. Determining subsurface ice concentration on Earth is not trivial and has been attempted previously with electrical resistivity tomography (ERT), ground penetrating radar (GPR), airborne EM (AEM), and nuclear magnetic resonance (NMR). These EM geophysical techniques do not actually detect ice, but rather the absence of unfrozen water. This causes a non-unique interpretation of frozen and dry subsurface sediments. This works well in the arctic because most locations are not dry. However, for planetary exploration, liquid water is exceedingly rare and subsurface mapping must discriminate between an ice-rich and a dry subsurface. Luckily, nature has provided a unique electrical signature of ice: its dielectric relaxation. The dielectric relaxation of ice creates a temperature and frequency dependence of the electrical properties and varies the relative dielectric permittivity from ~3.1 at radar frequencies to >100 at low frequencies. On Mars, sediments smaller than silt size can hold enough adsorbed unfrozen water to complicate the measurement. This is because the presence of absorbed water also creates frequency-dependent electrical properties. The dielectric relaxation of adsorbed water and ice can be separated as they have different shapes and frequency ranges as long as a spectrum spanning the two relaxations is measured. The volume concentration of ice and adsorbed water is a function of the strength of their relaxations. Therefore, we suggest that capacitively-coupled dielectric spectroscopy (a.k.a. spectral induced polarization or complex resistivity) can detect the concentration of both ice and adsorbed water in the subsurface. To prove this concept we have collected dielectric spectroscopy at the Cold Regions Research and Engineering Laboratory (CRREL) permafrost tunnel in Fox, AK. We were able to detect the ice relaxation in the subsurface despite the considerable amount of subsurface unfrozen water due to the presence of montmorillonite clay and much warmer temperatures than Mars or permanently shadowed regions of the Moon. While dielectric spectroscopy can be used to determine ice and adsorbed water content it does not possess the high resolution mapping capability of a GPR. Moreover, GPR cannot detect subsurface ice content in ice-sediment mixtures as evidenced in the interpretation of the Medusae Fossae Formation. Orbital radar surveys show this unit has a low attenuation and a dielectric permittivity near 4. This allows the formation to be interpreted as ice-rich or a dry high-porosity volcanic tuff unit. Therefore, combining GPR and dielectric spectroscopy will enable high-resolution structural and volatile mapping of the subsurface. Furthermore, the addition of neutron spectroscopy would add total hydrogen abundance in the top meter. This could lead to the determination of how much hydrogen resides in ice, adsorbed water, and minerals.

76 FR 35511 - Decommissioning Planning

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-17

..., which includes the site's subsurface soil and groundwater. Licensees also may be required to perform... structures, materials, soils, groundwater, and other media at a site resulting from activities under the.... Certain operational events (e.g., slow, long-term leaks), particularly those that cause subsurface soil...

Fiber Optic Bragg Grating Sensors for Thermographic Detection of Subsurface Anomalies

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Winfree, William P.; Wu, Meng-Chou

2009-01-01

Conventional thermography with an infrared imager has been shown to be an extremely viable technique for nondestructively detecting subsurface anomalies such as thickness variations due to corrosion. A recently developed technique using fiber optic sensors to measure temperature holds potential for performing similar inspections without requiring an infrared imager. The structure is heated using a heat source such as a quartz lamp with fiber Bragg grating (FBG) sensors at the surface of the structure to detect temperature. Investigated structures include a stainless steel plate with thickness variations simulated by small platelets attached to the back side using thermal grease. A relationship is shown between the FBG sensor thermal response and variations in material thickness. For comparison, finite element modeling was performed and found to agree closely with the fiber optic thermography results. This technique shows potential for applications where FBG sensors are already bonded to structures for Integrated Vehicle Health Monitoring (IVHM) strain measurements and can serve dual-use by also performing thermographic detection of subsurface anomalies.

Applications of Surface Penetrating Radar for Mars Exploration

NASA Astrophysics Data System (ADS)

Li, H.; Li, C.; Ran, S.; Feng, J.; Zuo, W.

2015-12-01

Surface Penetrating Radar (SPR) is a geophysical method that uses electromagnetic field probe the interior structure and lithological variations of a lossy dielectric materials, it performs quite well in dry, icy and shallow-soil environments. The first radar sounding of the subsurface of planet was carried out by Apollo Lunar Sounder Experiment (ALSE) of the Apollo 17 in 1972. ALSE provided very precise information about the moon's topography and revealed structures beneath the surface in both Mare Crisium and Mare Serenitatis. Russian Mars'92 was the first Mars exploration mission that tried to use SPR to explore martian surface, subsurface and ionosphere. Although Mars'96 launch failed in 1996, Russia(Mars'98, cancelled in 1998; Phobos-Grunt, launch failed in 2011), ESA(Mars Express, succeeded in 2003; Netlander, cancelled in 2003; ExoMars 2018) and NASA(MRO, succeeded in 2005; MARS 2020) have been making great effects to send SPR to Mars, trying to search for the existence of groundwater and life in the past 20 years. So far, no Ground Penetrating Radar(GPR) has yet provided in situ observations on the surface of Mars. In December 2013, China's CE-3 lunar rover (Yuto) equipped with a GPR made the first direct measurement of the structure and depth of the lunar soil, and investigation of the lunar crust structure along the rover path. China's Mars Exploration Program also plans to carry the orbiting radar sounder and rover GPR to characterize the nature of subsurface water or ices and the layered structure of shallow subsurface of Mars. SPR can provide diversity of applications for Mars exploration , that are: to map the distribution of solid and liquid water in the upper portions of the Mars' crust; to characterize the subsurface geologic environment; to investigate the planet's subsurface to better understand the evolution and habitability of Mars; to perform the martain ionosphere sounding. Based on SPR's history and achievements, combined with the development of radar technology, SPR's technological trends applied in moon and deep space exploration are summarized in the following: Technological convergence in SPR and SAR(Synthetic Aperture Radar); Muliti-frequency and Multi-polarization; Bistatic or multistatic SPRs for geophysical network; Tomography.

Dune advance into a coastal forest, equatorial Brazil: A subsurface perspective

NASA Astrophysics Data System (ADS)

Buynevich, Ilya V.; Filho, Pedro Walfir M. Souza; Asp, Nils E.

2010-06-01

A large active parabolic dune along the coast of Pará State, northern Brazil, was analyzed using aerial photography and imaged with high-resolution ground-penetrating radar (GPR) to map the subsurface facies architecture and point-source anomalies. Most high-amplitude (8-10 dB) subsurface anomalies are correlated with partially buried mangrove trees along the leading edge (slipface) of the advancing dune. Profiles along a 200-m long basal stoss side of the dune reveal 66 targets, most of which lie below the water table and are thus inaccessible by other methods. Signal amplitudes of point-source anomalies are substantially higher than those associated with the reflections from continuous subsurface features (water table, sedimentary layers). When complemented with exposures and excavations, GPR provides the best means of rapid continuous imaging of the geological record of complex interactions between vegetation and aeolian deposition.

Fault linkages and activities in a transition zone of compression to transpression in Hsinchu area, northwestern Taiwan based on 3-D structural geometry

NASA Astrophysics Data System (ADS)

Huang, H.; Hu, J.; Huang, S.; Huang, C.

2010-12-01

The Taiwan orogenic belt is resulted from the convergence between Philippine Sea plate and Eurasian plate. Serious earthquakes occurred in west and northwest flanks of main mountain belt of the island in 1935 and 1999, caused more than 5000 deaths in total. In addition, Hsinchu Science and Industrial Park (HSIP) located in northwest Taiwan is one of the world's most important areas for semiconductor manufacturing. There are more than 400 technology companies in this park, and accounted for 10% of Taiwan's GDP. Consequently, active Hsincheng and Hsinchu faults in study area become the major threat of the industrial park, thus the understanding of complex subsurface seismogenic structures are crucial issue of earthquake hazard assessment and mitigation in Hsinchu area. Several geological cross sections have been constructed and discussed to suggest possible deep structures of these two major faults in previous study. However, how subsurface fault system and folding intersect still remains unclear and the evolution of fault and fold geometry in Hsinchu area is not fully understood. The main purpose of this study is to clarify the spatial linkage between the major thrust faults, folds, and adjacent transverse structures. In this study, we first construct the NW-SE trending cross-section which is sub-parallel to the regional shortening direction, and then balance this cross section to derive the structure evolution in Hsinchu area. We also incorporate several cross-sections and relocated seismicity to get detail 3D fault geometry for the numerical modeling in order to assess the interseismic strain accumulation and seismic potential based on geodetic measurements.

Fiber Optic Thermographic Detection of Flaws in Composites

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.

2009-01-01

Optical fibers with multiple Bragg gratings bonded to surfaces of structures were used for thermographic detection of subsurface defects in structures. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The obtained data were analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with the simulation results.

Empirical relationship between electrical resistivity and geotechnical parameters: A case study of Federal University of Technology campus, Akure SW, Nigeria

NASA Astrophysics Data System (ADS)

Akintorinwa, O. J.; Oluwole, S. T.

2018-06-01

For several decades, geophysical prospecting method coupled with geotechnical analysis has become increasingly useful in evaluating the subsurface for both pre and post engineering investigations. Shallow geophysical tool is often used alongside geotechnical method to evaluate subsurface soil for engineering study to obtain information which may include the subsurface lithology and their thicknesses, competence of the bedrock and depths to its upper interface, and competence of the material that make up the overburden, especially the shallow section which serves as host for foundations of engineering structures (Aina et al., 1996; Adewumi and Olorunfemi, 2005; and Idornigie et al., 2006). This information helps the engineers to correctly locate and design the foundation of engineering structures. The information also serves as guide to the choice of design and suitable materials needed for road construction (Akinlabi and Adeyemi, 2014). Lack of knowledge of the properties of subsurface may leads to the failure of most engineering structures. Therefore, it is of great importance to carry out a pre-construction investigation of a proposed site in order to ascertain the fitness of the host earth material.

Pd surface and Pt subsurface segregation in Pt1-c Pd c nanoalloys

NASA Astrophysics Data System (ADS)

De Clercq, A.; Giorgio, S.; Mottet, C.

2016-02-01

The structure and chemical arrangement of Pt1-c Pd c nanoalloys with the icosahedral and face centered cubic symmetry are studied using Monte Carlo simulations with a tight binding interatomic potential fitted to density-functional theory calculations. Pd surface segregation from the lowest to the highest coordinated sites is predicted by the theory together with a Pt enrichment at the subsurface, whatever the structure and the size of the nanoparticles, and which subsists when increasing the temperature. The onion-shell chemical configuration is found for both symmetries and is initiated from the Pd surface segregation. It is amplified in the icosahedral symmetry and small sizes but when considering larger sizes, the oscillating segregation profile occurs near the surface on about three to four shells whatever the structure. Pd segregation results from the significant lower cohesive energy of Pd as compared to Pt and the weak ordering tendency leads to the Pt subsurface segregation. The very weak size mismatch does not prevent the bigger atoms (Pt) from occupying subsurface sites which are in compression whereas the smaller ones (Pd) occupy the central site of the icosahedra where the compression is an order of magnitude higher.

Geophysical framework of the southwestern Nevada volcanic field and hydrogeologic implications

USGS Publications Warehouse

Grauch, V.J.; Sawyer, David A.; Fridrich, Chris J.; Hudson, Mark R.

1999-01-01

Gravity and magnetic data, when integrated with other geophysical, geological, and rock-property data, provide a regional framework to view the subsurface geology in the southwestern Nevada volcanic field. The region has been loosely divided into six domains based on structural style and overall geophysical character. For each domain, the subsurface tectonic and magmatic features that have been inferred or interpreted from previous geophysical work has been reviewed. Where possible, abrupt changes in geophysical fields as evidence for potential structural lithologic control on ground-water flow has been noted. Inferred lithology is used to suggest associated hydrogeologic units in the subsurface. The resulting framework provides a basis for investigators to develop hypotheses from regional ground-water pathways where no drill-hole information exists.

Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

USGS Publications Warehouse

Brooks, G.A.; Olyphant, G.A.; Harper, D.

1991-01-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine. ?? 1991 Springer-Verlag New York Inc.

Application of electromagnetic techniques in survey of contaminated groundwater at an abandoned mine complex in southwestern Indiana, U.S.A.

NASA Astrophysics Data System (ADS)

Brooks, Glenn A.; Olyphant, Greg A.; Harper, Denver

1991-07-01

In part of a large abandoned mining complex, electromagnetic geophysical surveys were used along with data derived from cores and monitoring wells to infer sources of contamination and subsurface hydrologic connections between acidic refuse deposits and adjacent undisturbed geologic materials. Electrical resistivity increases sharply along the boundary of an elevated deposit of pyritic coarse refuse, which is highly contaminated and electrically conductive, indicating poor subsurface hydrologic connections with surrounding deposits of fine refuse and undisturbed glacial material. Groundwater chemistry, as reflected in values of specific conductance, also differs markedly across the deposit's boundary, indicating that a widespread contaminant plume has not developed around the coarse refuse in more than 40 yr since the deposit was created. Most acidic drainage from the coarse refuse is by surface runoff and is concentrated around stream channels. Although most of the contaminated groundwater within the study area is concentrated within the surficial refuse deposits, transects of apparent resistivity and phase angle indicate the existence of an anomalous conductive layer at depth (>4 m) in thick alluvial sediments along the northern boundary of the mining complex. Based on knowledge of local geology, the anomaly is interpreted to represent a subsurface connection between the alluvium and a flooded abandoned underground mine.

Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development

NASA Astrophysics Data System (ADS)

Korteniemi, J.; Kukkonen, S.

2018-04-01

Outflow channel formation on the eastern Hellas rim region is traditionally thought to have been triggered by activity phases of the nearby volcanoes Hadriacus and Tyrrhenus Montes: As a result of volcanic heating subsurface volatiles were mobilized. It is, however, under debate, whether eastern Hellas volcanism was in fact more extensive, and if there were volcanic centers separate from the identified central volcanoes. This work describes previously unrecognized structures in the Niger-Dao Valles outflow channel complex. We interpret them as volcanic edifices: cones, a shield, and a caldera. The structures provide evidence of an additional volcanic center within the valles and indicate volcanic activity both prior to and following the formation of the outflow events. They expand the extent, type, and duration of volcanic activity in the Circum-Hellas Volcanic Province and provide new information on interaction between volcanism and fluvial activity.

Aeromagnetic and aeromagnetic-based geologic maps of the Coastal Belt, Franciscan Complex, northern California

USGS Publications Warehouse

Langenheim, V.E.; Jachens, R.C.; McLaughlin, R.J.

2011-01-01

The Coastal belt of the Franciscan Complex represents a Late Cretaceous to Miocene accretionary prism and overlying slope deposits. Its equivalents may extend from the offshore outer borderland of southern California to north of the Mendocino Triple Junction under the Eel River Basin and in the offshore of Cascadia. The Coastal belt is exposed on land in northern California, yet its structure and stratigraphy are incompletely known because of discontinuous exposure, structural disruption, and lithologically non-distinctive clastic rocks. The intent of this report is to make available, in map form, aeromagnetic data covering the Coastal belt that provide a new dataset to aid in mapping, understanding, and interpreting the incompletely understood geology and structure in northern California.The newly merged aeromagnetic data over the Coastal belt of the Franciscan Complex reveal long, linear anomalies that indicate remarkably coherent structure within a terrane where mapping at the surface indicates complex deformation and that has been described as "broken formation" and, even locally as "mélange". The anomalies in the Coastal belt are primarily sourced by volcanic-rich graywackes and exotic blocks of basalt. Some anomalies along the contact of the Coastal belt with the Central belt are likely caused by local interleaving of components of the Coast Ranges ophiolite. These data can be used to map additional exotic blocks within the Coastal belt and to distinguish lithologically indistinct graywackes within the Coastal terrane. Using anomaly asymmetry allows projection of these "layers" into the subsurface. This analysis indicates predominant northeast dips consistent with tectonic interleaving of blocks within a subduction zone.

Evaluating the Competitive Use of the Subsurface: The Influence of Energy Storage and Production in Groundwater

NASA Astrophysics Data System (ADS)

Helmig, R.; Becker, B.; Flemisch, B.

2015-12-01

The natural subsurface is gaining in importance for a variety of engineering applications related to energy supply. At the same time it is already utilized in many ways. On the one hand, the subsurface with its groundwater system represents the most important source of drinking water; on the other hand, it contains natural resources such as petroleum, natural gas and coal. In recent years, the subsurface has been gaining importance as a resource of energy and as an energy and waste repository. It can serve as a short-, medium- or long-term storage medium for energy in various forms, e.g. in the form of methane (CH4), hydrogen (H2) or compressed air. The subsurface is also attracting increasing interest as a natural source of energy, regarding, for instance, the extraction of fossil methane by hydraulic fracturing or the utilization of geothermal energy as a renewable energy source. As a result, with increasing exploitation, resource conflicts are becoming more and more common and complex. Modeling concepts for simulating multiphase flow that can reproduce the high complexity of the underlying processes in an efficient way need to be developed. The application of these model concepts is of great importance with respect to feasibility, risk analysis, storage capacity and sensitivity issues. This talk will give an overview on possible utilization conflicts in subsurface systems and how the groundwater is affected. It will focus on presenting fundamental properties and functions of a compositional multiphase system in a porous medium and introduce basic multiscale and multiphysics concepts as well as formulate conser­vation laws for simulating energy storage in the subsurface. Large-scale simulations that show the general applicability of the modeling concepts of such complicated natural systems, especially the impact on the groundwater of simultaneously using geothermal energy and storing chemical and thermal energy, and how such real large-scale systems provide a good environment for balancing the efficiency potential and possible weaknesses of the approaches will be discussed.

Effects of mesoscale structures on the distribution of cephalopod paralarvae in the Gulf of California and adjacent Pacific

NASA Astrophysics Data System (ADS)

Ruvalcaba-Aroche, Erick D.; Sánchez-Velasco, Laura; Beier, Emilio; Godínez, Victor M.; Barton, Eric D.; Pacheco, Ma. Rocío

2018-01-01

Vertical distribution of the cephalopod paralarvae was investigated in relation to a system of two cyclonic and three anticyclonic eddies in the southern Gulf of California and a front in the adjacent Pacific Ocean. Results showed that the preferential habitat for the Sthenoteuthis oualaniensis - Dosidicus gigas "SD-complex" in both regions was the oxygenated surface mixed layer and the thermocline. The highest abundances occurred in of one of the anticyclonic eddies and a frontal zone, which are convergent structures. Enoploteuthid and Pyroteuthid paralarvae both displayed their highest abundances in the thermocline. Pyroteuthids dominated in the cyclonic eddy whereas Enoploteuthidae were less evident in the eddy system. Pyroteuthids were observed on the western (California Current) side of the frontal zone, and Enoploteuthids on its eastern (Gulf of California) side. The octopods and the complex of Ommastrephes-Eucleoteuthis-Hyaloteuthis paralarvae were present below the thermocline. Both groups had a scarce presence in the eddy system and high abundance near the frontal zone. The octopods abounded on the eastern side in association with the low dissolved oxygen concentrations (< 44 μmol kg-1) of Subtropical-Subsurface Water; the complex on the western front side was immersed in California Current Water. It may be concluded that the spawning and early stages of development of these cephalopod groups are associated with particular mesoscale structures of the water masses. For example, the "SD complex" inhabits the surface water masses, preferentially in convergence zones generated by mesoscale activity.

Numerical modeling of Gaussian beam propagation and diffraction in inhomogeneous media based on the complex eikonal equation

NASA Astrophysics Data System (ADS)

Huang, Xingguo; Sun, Hui

2018-05-01

Gaussian beam is an important complex geometrical optical technology for modeling seismic wave propagation and diffraction in the subsurface with complex geological structure. Current methods for Gaussian beam modeling rely on the dynamic ray tracing and the evanescent wave tracking. However, the dynamic ray tracing method is based on the paraxial ray approximation and the evanescent wave tracking method cannot describe strongly evanescent fields. This leads to inaccuracy of the computed wave fields in the region with a strong inhomogeneous medium. To address this problem, we compute Gaussian beam wave fields using the complex phase by directly solving the complex eikonal equation. In this method, the fast marching method, which is widely used for phase calculation, is combined with Gauss-Newton optimization algorithm to obtain the complex phase at the regular grid points. The main theoretical challenge in combination of this method with Gaussian beam modeling is to address the irregular boundary near the curved central ray. To cope with this challenge, we present the non-uniform finite difference operator and a modified fast marching method. The numerical results confirm the proposed approach.

Transport of Chemical Vapors from Subsurface Sources to Atmosphere as Affected by Shallow Subsurface and Atmospheric Conditions

NASA Astrophysics Data System (ADS)

Rice, A. K.; Smits, K. M.; Hosken, K.; Schulte, P.; Illangasekare, T. H.

2012-12-01

Understanding the movement and modeling of chemical vapor through unsaturated soil in the shallow subsurface when subjected to natural atmospheric thermal and mass flux boundary conditions at the land surface is of importance to applications such as landmine detection and vapor intrusion into subsurface structures. New, advanced technologies exist to sense chemical signatures at the land/atmosphere interface, but interpretation of these sensor signals to make assessment of source conditions remains a challenge. Chemical signatures are subject to numerous interactions while migrating through the unsaturated soil environment, attenuating signal strength and masking contaminant source conditions. The dominant process governing movement of gases through porous media is often assumed to be Fickian diffusion through the air phase with minimal or no quantification of other processes contributing to vapor migration, such as thermal diffusion, convective gas flow due to the displacement of air, expansion/contraction of air due to temperature changes, temporal and spatial variations of soil moisture and fluctuations in atmospheric pressure. Soil water evaporation and interfacial mass transfer add to the complexity of the system. The goal of this work is to perform controlled experiments under transient conditions of soil moisture, temperature and wind at the land/atmosphere interface and use the resulting dataset to test existing theories on subsurface gas flow and iterate between numerical modeling efforts and experimental data. Ultimately, we aim to update conceptual models of shallow subsurface vapor transport to include conditionally significant transport processes and inform placement of mobile sensors and/or networks. We have developed a two-dimensional tank apparatus equipped with a network of sensors and a flow-through head space for simulation of the atmospheric interface. A detailed matrix of realistic atmospheric boundary conditions was applied in a series of experiments. Water saturation, capillary pressure, air and soil temperature, and relative humidity were continuously monitored. Aqueous TCE was injected into the tank below the water table and allowed to volatilize. TCE concentration exiting the tank head space was measured through interval sampling by direct injection into a gas chromatograph. To quantify the transient concentration of TCE vapor in the soil pore space a novel use of Solid Phase Micro-Extraction (SPME) was developed. Results from our numerical simulations were compared with the experimental data, which demonstrated the importance of considering the interaction of the atmosphere with the subsurface in conceptualization and numerical model development. Results also emphasize that soil saturation and transient sorption have a significant effect on vapor transport through the vadose zone. Follow-up tests and detailed analyses are still underway. Additional applications of this work include carbon sequestration leakage, methane contamination in the shallow subsurface and environmental impact of hydraulic fracturing.

Subsurface flow and vegetation patterns in tidal environments

NASA Astrophysics Data System (ADS)

Ursino, Nadia; Silvestri, Sonia; Marani, Marco

2004-05-01

Tidal environments are characterized by a complex interplay of hydrological, geomorphic, and biological processes, and their understanding and modeling thus require the explicit description of both their biotic and abiotic components. In particular, the presence and spatial distribution of salt marsh vegetation (a key factor in the stabilization of the surface soil) have been suggested to be related to topographic factors and to soil moisture patterns, but a general, process-based comprehension of this relationship has not yet been achieved. The present paper describes a finite element model of saturated-unsaturated subsurface flow in a schematic salt marsh, driven by tidal fluctuations and evapotranspiration. The conditions leading to the establishment of preferentially aerated subsurface zones are studied, and inferences regarding the development and spatial distribution of salt marsh vegetation are drawn, with important implications for the overall ecogeomorphological dynamics of tidal environments. Our results show that subsurface water flow in the marsh induces complex water table dynamics, even when the tidal forcing has a simple sinusoidal form. The definition of a space-dependent aeration time is then proposed to characterize root aeration. The model shows that salt marsh subsurface flow depends on the distance from the nearest creek or channel and that the subsurface water movement near tidal creeks is both vertical and horizontal, while farther from creeks, it is primarily vertical. Moreover, the study shows that if the soil saturated conductivity is relatively low (10-6 m s-1, values quite common in salt marsh areas), a persistently unsaturated zone is present below the soil surface even after the tide has flooded the marsh; this provides evidence of the presence of an aerated layer allowing a prolonged presence of oxygen for aerobic root respiration. The results further show that plant transpiration increases the extent and persistence of the aerated layer, thereby introducing a strong positive feedback: Pioneer plants on marsh edges have the effect of increasing soil oxygen availability, thus creating the conditions for the further development of other plant communities.

A Benchmarking Initiative for Reactive Transport Modeling Applied to Subsurface Environmental Applications

NASA Astrophysics Data System (ADS)

Steefel, C. I.

2015-12-01

Over the last 20 years, we have seen the evolution of multicomponent reactive transport modeling and the expanding range and increasing complexity of subsurface environmental applications it is being used to address. Reactive transport modeling is being asked to provide accurate assessments of engineering performance and risk for important issues with far-reaching consequences. As a result, the complexity and detail of subsurface processes, properties, and conditions that can be simulated have significantly expanded. Closed form solutions are necessary and useful, but limited to situations that are far simpler than typical applications that combine many physical and chemical processes, in many cases in coupled form. In the absence of closed form and yet realistic solutions for complex applications, numerical benchmark problems with an accepted set of results will be indispensable to qualifying codes for various environmental applications. The intent of this benchmarking exercise, now underway for more than five years, is to develop and publish a set of well-described benchmark problems that can be used to demonstrate simulator conformance with norms established by the subsurface science and engineering community. The objective is not to verify this or that specific code--the reactive transport codes play a supporting role in this regard—but rather to use the codes to verify that a common solution of the problem can be achieved. Thus, the objective of each of the manuscripts is to present an environmentally-relevant benchmark problem that tests the conceptual model capabilities, numerical implementation, process coupling, and accuracy. The benchmark problems developed to date include 1) microbially-mediated reactions, 2) isotopes, 3) multi-component diffusion, 4) uranium fate and transport, 5) metal mobility in mining affected systems, and 6) waste repositories and related aspects.

Design and Evaluation of a Fiber Optic Probe as a means of Subsurface Planetary Exploration

NASA Astrophysics Data System (ADS)

Pilgrim, Robert Paul

The Optical Probe for Regolith Analysis (OPRA) is an instrumentation concept designed to provide spectroscopic analysis of the near subsurface of unconsolidated regolith on bodies such as moons, asteroids and planets. Below a chemically altered surface may lay the geological history in the form of stratigraphy that is shielded from degradation due to harsh external environments. Most of what we know about our solar system comes from remote platforms, such as satellites that are deployed into orbit around the target body. In the case of Mars, we have had several successful landers and rovers however, with the exception of the Mars Science Laboratory that just drilled its first hole, the complexity of subsurface excavation has limited the extent of subsurface exploration to simple scoops deployed on the ends of robotic arms which, by their very nature, will erase any stratigraphy that it may be digging into. The OPRA instrumentation concept allows for an integrated, lightweight and simple apparatus for subsurface exploration via a small, spike like structure which contains integrated optical fibers coupled to small windows running down the length of the probe. Each window is connected to a spectrometer housed onboard the deploying spacecraft. Each window is separately interrogated via the spectrometer over the wavelength range 1-2.5 nm to produce a spectroscopic profile as a function of depth. This project takes the Technology Readiness Level (TRL) of the OPRA instrumentation concept to level 3, which is defined by NASA to be the demonstration either analytically or experimentally of the proof of concept for critical functions of the proposed instrument. Firstly, to demonstrate that optical fibers are feasible for this type of application, we report on the techniques used by NASA to space qualify optical fibers. We investigate the optical performance of several fiber optic bundle configurations, both experimentally and numerically, to help optimize bundle performance. Optical bundles were then spectrally validated via a series of spectral comparisons between standardized reflectance spectroscopy targets and spectra obtained with the bundles. We also report on the integration of fiber optical bundles into other research and experimental results from several other groups within our research teams to obtain spectra under a more "space like" environment. Finally, the probe housing structural performance was investigated via finite element analysis, using probe penetration forces derived from data analysis of experimentation conducted by the Apollo lunar missions, and investigations into a mechanical analogue for the Martian regolith.

3D Geological Mapping - uncovering the subsurface to increase environmental understanding

NASA Astrophysics Data System (ADS)

Kessler, H.; Mathers, S.; Peach, D.

2012-12-01

Geological understanding is required for many disciplines studying natural processes from hydrology to landscape evolution. The subsurface structure of rocks and soils and their properties occupies three-dimensional (3D) space and geological processes operate in time. Traditionally geologists have captured their spatial and temporal knowledge in 2 dimensional maps and cross-sections and through narrative, because paper maps and later two dimensional geographical information systems (GIS) were the only tools available to them. Another major constraint on using more explicit and numerical systems to express geological knowledge is the fact that a geologist only ever observes and measures a fraction of the system they study. Only on rare occasions does the geologist have access to enough real data to generate meaningful predictions of the subsurface without the input of conceptual understanding developed from and knowledge of the geological processes responsible for the deposition, emplacement and diagenesis of the rocks. This in turn has led to geology becoming an increasingly marginalised science as other disciplines have embraced the digital world and have increasingly turned to implicit numerical modelling to understand environmental processes and interactions. Recent developments in geoscience methodology and technology have gone some way to overcoming these barriers and geologists across the world are beginning to routinely capture their knowledge and combine it with all available subsurface data (of often highly varying spatial distribution and quality) to create regional and national geological three dimensional geological maps. This is re-defining the way geologists interact with other science disciplines, as their concepts and knowledge are now expressed in an explicit form that can be used downstream to design process models structure. For example, groundwater modellers can refine their understanding of groundwater flow in three dimensions or even directly parameterize their numerical models using outputs from 3D mapping. In some cases model code is being re-designed in order to deal with the increasing geological complexity expressed by Geologists. These 3D maps contain have inherent uncertainty, just as their predecessors, 2D geological maps had, and there remains a significant body of work to quantify and effectively communicate this uncertainty. Here we present examples of regional and national 3D maps from Geological Survey Organisations worldwide and how these are being used to better solve real-life environmental problems. The future challenge for geologists is to make these 3D maps easily available in an accessible and interoperable form so that the environmental science community can truly integrate the hidden subsurface into a common understanding of the whole geosphere.

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE PAGES

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

2018-04-11

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

Monitoring microbial growth and activity using spectral induced polarization and low-field nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Zhang, Chi; Keating, Kristina; Revil, Andre

2015-04-01

Microbes and microbial activities in the Earth's subsurface play a significant role in shaping subsurface environments and are involved in environmental applications such as remediation of contaminants in groundwater and oil fields biodegradation. Stimulated microbial growth in such applications could cause wide variety of changes of physical/chemical properties in the subsurface. It is critical to monitor and determine the fate and transportation of microorganisms in the subsurface during such applications. Recent geophysical studies demonstrate the potential of two innovative techniques, spectral induced polarization (SIP) and low-field nuclear magnetic resonance (NMR), for monitoring microbial growth and activities in porous media. The SIP measures complex dielectric properties of porous media at low frequencies of exciting electric field, and NMR studies the porous structure of geologic media and characterizes fluids subsurface. In this laboratory study, we examined both SIP and NMR responses from bacterial growth suspension as well as suspension mixed with silica sands. We focus on the direct contribution of microbes to the SIP and NMR signals in the absence of biofilm formation or biomineralization. We used Zymomonas mobilis and Shewanella oneidensis (MR-1) for SIP and NMR measurements, respectively. The SIP measurements were collected over the frequency range of 0.1 - 1 kHz on Z. mobilis growth suspension and suspension saturated sands at different cell densities. SIP data show two distinct peaks in imaginary conductivity spectra, and both imaginary and real conductivities increased as microbial density increased. NMR data were collected using both CPMG pulse sequence and D-T2 mapping to determine the T2-distribution and diffusion properties on S. oneidensis suspension, pellets (live and dead), and suspension mixed with silica sands. NMR data show a decrease in the T2-distribution in S. oneidensis suspension saturated sands as microbial density increase. A clear distinction in the T2-distribution and D-T2 plots between live and dead cell pellets was also observed. These results will provide a basis for understanding the effect of microbes within geologic media on SIP and low-field NMR measurements. This research suggests that both SIP and NMR have the potential to monitor microbial growth and activities in the subsurface and could provide spatiotemporal variations in bacterial abundance in porous media.

The nature and function of microbial enzymes in subsurface marine sediments

NASA Astrophysics Data System (ADS)

Steen, A. D.; Schmidt, J.

2016-02-01

Isotopic and genomic evidence indicates that marine sediments contain populations of active heterotrophic microorganisms which appear to metabolize old, detrital, apparently recalcitrant organic matter. In surface communities, heterotrophs use extracellular enzymes to access complex organic matter. In subsurface sediments, in which microbial doubling times can be on the order of hundreds or thousands of years, it is not clear whether extracellular enzymes could remain stable and active long enough to constitute a 'profitable' stragtegy for accessing complex organic carbon. Here we present evidence that a wide range of extracellular enzyme are active in subsurface sediments from two different environments: the White Oak River, NC, and deep (up to 80 m) sediments of the Baltic Sea Basin recovered from IODP Expedition 347. In the White Oak River, enzymes from deeper sediments appear to be better-adapted to highly-degraded organic matter than enzymes from surface sediments. In the Baltic Sea, preliminary data suggest that enzymes related to nitrogen acquisition are preferentially expressed. By characterizing the extracellular enzymes present in marine sediments, we hope to achieve a better understanding of the mechanisms that control sedimentary organic matter remineralization and preservation.

Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

DOEpatents

Ellingson, William A.; Brada, Mark P.

1995-01-01

A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser's wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known "feature masks" of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects.

Subsurface damage detection in non-ferrous systems using 3D synchronous magnetic inspection

NASA Astrophysics Data System (ADS)

Gray, David; Berry, David

2018-04-01

Prime Photonics is developing a non-destructive inspection (NDI) technology, 3-D synchronous magnetic imaging system (3-D SMIS), that uses synchronous detection of magnetic signatures resulting from ultrasonic excitation to measure both surface and subsurface flaws in conductive structures. 3-D SMIS is showing promise in a wide range of NDI/NDE uses including characterizing surface-breaking cracks in ferrous and non-ferrous materials, locating and characterizing subsurface cracks within nonferrous conductive materials (Ti 6-4 and carbon fiber composites), and characterization of subsurface residual stresses. The technology offers a non-contact, high resolution inspection technique that does not require austere environments, and can accommodate non-planar specimen geometries.

Evaluation of field methods for vertical high resolution aquifer characterization

NASA Astrophysics Data System (ADS)

Vienken, T.; Tinter, M.; Rogiers, B.; Leven, C.; Dietrich, P.

2012-12-01

The delineation and characterization of subsurface (hydro)-stratigraphic structures is one of the challenging tasks of hydrogeological site investigations. The knowledge about the spatial distribution of soil specific properties and hydraulic conductivity (K) is the prerequisite for understanding flow and fluid transport processes. This is especially true for heterogeneous unconsolidated sedimentary deposits with a complex sedimentary architecture. One commonly used approach to investigate and characterize sediment heterogeneity is soil sampling and lab analyses, e.g. grain size distribution. Tests conducted on 108 samples show that calculation of K based on grain size distribution is not suitable for high resolution aquifer characterization of highly heterogeneous sediments due to sampling effects and large differences of calculated K values between applied formulas (Vienken & Dietrich 2011). Therefore, extensive tests were conducted at two test sites under different geological conditions to evaluate the performance of innovative Direct Push (DP) based approaches for the vertical high resolution determination of K. Different DP based sensor probes for the in-situ subsurface characterization based on electrical, hydraulic, and textural soil properties were used to obtain high resolution vertical profiles. The applied DP based tools proved to be a suitable and efficient alternative to traditional approaches. Despite resolution differences, all of the applied methods captured the main aquifer structure. Correlation of the DP based K estimates and proxies with DP based slug tests show that it is possible to describe the aquifer hydraulic structure on less than a meter scale by combining DP slug test data and continuous DP measurements. Even though correlations are site specific and appropriate DP tools must be chosen, DP is reliable and efficient alternative for characterizing even strongly heterogeneous sites with complex structured sedimentary aquifers (Vienken et al. 2012). References: Vienken, T., Leven, C., and Dietrich, P. 2012. Use of CPT and other direct push methods for (hydro-) stratigraphic aquifer characterization — a field study. Canadian Geotechnical Journal, 49(2): 197-206. Vienken, T., and Dietrich, P. 2011. Field evaluation of methods for determining hydraulic conductivity from grain size data. Journal of Hydrology, 400(1-2): 58-71.

Peatland Structural Controls on Spring Distribution

NASA Astrophysics Data System (ADS)

Hare, D. K.; Boutt, D. F.; Hackman, A. M.; Davenport, G.

2013-12-01

The species richness of wetland ecosystems' are sustained by the presence of discrete groundwater discharge, or springs. Springs provide thermal refugia and a source of fresh water inflow crucial for survival of many wetland species. The subsurface drivers that control the spatial distribution of surficial springs throughout peatland complexes are poorly understood due to the many challenges peatlands pose for hydrologic characterization, such as the internal heterogeneities, soft, dynamic substrate, and low gradient of peat drainage. This has previously made it difficult to collect spatial data required for restoration projects that seek to support spring obligate and thermally stressed species such as trout. Tidmarsh Farms is a 577-acre site in Southeastern Massachusetts where 100+ years of cranberry farming has significantly altered the original peatland hydrodynamics and ecology. Farming practices such as the regular application of sand, straightening of the main channel, and addition of drainage ditches has strongly degraded this peatland ecosystem. Our research has overlain non-invasive geophysical, thermal, and water isotopic data from the Tidmarsh Farms peatland to provide a detailed visualization of how subsurface peat structure and spring patterns correlate. Ground penetrating radar (GPR) has proven particularly useful in characterizing internal peat structure and the mineral soil interface beneath peatlands, we interpolate the peatland basin at a large scale (1 km2) and compare this 3-D surface to the locations of springs on the peat platform. Springs, expressed as cold anomalies in summer and warm anomalies in winter, were specifically located by combining fiber-optic and infrared thermal surveys, utilizing the numerous relic agricultural drainage ditches as a sampling advantage. Isotopic signatures of the spring locations are used to distinguish local and regional discharge, differences that can be explained in part by the peat basin structure delineated with GPR. The study expands our understanding of complex peat systems and will be used to inform wetland restoration based on hydrodynamic processes; yielding a more successful, resilient restoration and desired ecologic function. Our research demonstrates how the use of GPR in combination with thermal imagery and isotopic analysis can help characterize degraded peatlands, informing a process-based approach to ecological restoration of the site with the ability to monitor changes through time.

Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

NASA Astrophysics Data System (ADS)

Annewandter, Robert

2014-05-01

The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite volume method. The parabolic and hyperbolic problem can be solved separately by operator-splitting. The resulting system of linear equations is solved by the algebraic multigrid library SAMG, developed at the Fraunhofer Institute for Algorithms and Scientific Computing, Germany. CSMP++ is developed at Montan University of Leoben, ETH Zuerich, Imperial College London and Heriot-Watt University in Edinburgh. This study examines barometric pumping-driven subsurface transport of Xe-135, Xe-133m, Xe-133, Xe-131m including I-131, I-133 and I-135 on arrival times and isotopic activity ratios. This work was funded by the CTBTO Research Award for Young Scientist and Engineers (2013).

Exposed Fractured Bedrock in the Central Pit of a Crater

NASA Image and Video Library

2016-11-09

This HiRISE image shows the central pit feature of an approximately 20-kilometer diameter complex crater in located at 304.480 degrees east, -11.860 degrees south, just north of the Valles Marineris. Here we can observe a partial ring of light-toned, massive and fractured bedrock, which has been exposed by the impact-forming event, and via subsequent erosion that typically obscure the bedrock of complex central features. Features such as this one are of particular interest as they provide scientists with numerous exposures of bedrock that can be readily observed from orbit and originate from the deep Martian subsurface. Unlike on Earth, plate tectonics do not appear to be active on Mars. Thus, much of the Martian subsurface is not directly observable through uplift, erosion and exposure of mountain chains, which provide the majority of bedrock exposures on Earth. Exposures of subsurface materials generated by these features provides us with some of the only "windows" into the subsurface geology. This makes the study of impact craters an invaluable source of information when trying to understand, not only the impact process, but also the composition and history of Mars. Although much of what we see here is composed of massive and fractured bedrock, there are zones of rock fragmentation, called "brecciation." These fragmented rocks (a.k.a., breccias) are best viewed in the eastern portion of the central pit, which was captured in a previous HiRISE image. Additionally, we see some occurrences of impact melt-bearing deposits that surround and coat the bedrock exposed within the central pit. Several dunes are on the surface throughout the central pit and surrounding crater floor. The mechanisms behind the formation of central features, particularly central pits, are not completely understood. Geologic mapping of these circumferential "mega" blocks of bedrock indicate radial and concentric fracturing that is consistent with deformation through uplift. The exposed bedrock shows well-expressed lineament features that are likely fractures and faults formed during the uplift process. Studies of the bedrock, and such structures in this image, allows us better to understand the formative events and physical processes responsible for their formation. Current research suggests that their formation is the result of some component of uplift followed by collapse. http://photojournal.jpl.nasa.gov/catalog/PIA21205

Tracer transport in soils and shallow groundwater: model abstraction with modern tools

USDA-ARS?s Scientific Manuscript database

Vadose zone controls contaminant transport from the surface to groundwater, and modeling transport in vadose zone has become a burgeoning field. Exceedingly complex models of subsurface contaminant transport are often inefficient. Model abstraction is the methodology for reducing the complexity of a...

Realizing 2D magnetotelluric inversion in the case of divergent geoelectric strike directions in the crust and mantle - Case study using synthetic models and real data from the Tajo Basin (Spain)

NASA Astrophysics Data System (ADS)

Schmoldt, J.; Jones, A. G.; Muller, M. R.; Kiyan, D.; Hogg, C.; Rosell, O.

2010-12-01

Two-dimensional (2D) inversions of magnetotelluric (MT) data are presently far more commonly used than three-dimensional (3D) inversions as they still significantly outperform 3D inversions in terms of speed, thus allowing for much better resolution of the subsurface through a larger feasible number of grid cells. The suitability of 2D inversion needs thereby to be tested for cases where the electric resistivity structure of the subsurface is potentially 3D to some extent. One particular case of a 3D subsurface structure consists of lateral interfaces with varying orientations at crustal and mantle depths. Such a case might emerge, for instance, where crustal faulting, originating from present day tectonics, is situated above a mantle where structures are dominated by earlier or current plate tectonic processes. Those plate tectonic processes could comprise continental collision from an oblique direction, or lattice preferred orientation in the lithosphere-asthenosphere transition zone due to an oblique relative motion between lithosphere and asthenosphere. Whereas recovery of crustal structures can usually be achieved in a straightforward manner by confining the modelled frequency range to the crustal depths, deriving mantle structures is more challenging. Different approaches for this case have been investigated here using synthetic model studies as well as inversion of a real MT dataset collected in southern Spain as part of the PICASSO fieldwork campaign. The PICASSO project intends to enhance knowledge about the geological setting of the Alboran Domain beneath the western Mediterranean Sea and its surrounding regions, and through that knowledge to understand processes related to continent-continent collision. The Iberian Peninsula is the focus of the first phase of DIAS’s PICASSO efforts, and comprised a magnetotelluric profile crossing the Tajo Basin and Betics Cordillera. Analyses of MT responses and seismic tomography data indicate varying geologic strike direction with depth and along the profile. Geoelectric strike direction in the Tajo Basin crust is approximately NW-SE, coinciding with the direction of the Iberian Range and Neogene faults, whereas at mantle depths a dominant NNE-SSW direction is determined; the Betics region on the contrary exhibits a highly 3D structure originating from its complex tectonic orogeny. This circumstance motivated separate inversions for crustal and mantle structures of the Tajo Basin, as well as for the Betics region. Inversion results of the Tajo Basin subsurface indicate a relatively conducting upper crust underlain by more resistive structures in the lower crust and mantle. The most noticeable features of the models are the apparent upward extension of an electrical resistive lower crustal layer beneath the centre of the basin and the presence of a resistive mantle region that coincides with an area of low seismic velocity. The later indicates an unusual geological situation since typical causes for decreased seismic velocity, e.g. higher temperature, fluids, and less depleted rock chemistry, are commonly thought to decrease electric resistivity.

Cretaceous biostratigraphy in the Wyoming thrust belt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nichols, D.J.; Jacobson, S.R.

Biostratigraphy is essential to exploration for oil and gas in the Wyoming thrust belt because fossils provide a temporal framework for interpretation of events of faulting, erosion, sedimentation, and the development of hydrocarbon traps and migration pathways. In the Cretaceous section, fossils are especially useful for dating and correlating repetitive facies of different ages in structurally complex terrain. The biostratigraphic zonation for the region is based on megafossils (chiefly ammonites), which permit accurate dating and correlation of outcrop sections, and which have been calibrated with the radiometric time scale for the Western Interior. Molluscan and vertebrate zone fossils are difficultmore » to obtain from the subsurface, however, and ammonities are restricted to rocks of margin origin. Palynomorphs (plant microfossils) have proven to be the most valuable fossils in investigations of stratigraphy and structures in the subsurface of the thrust belt because palynomorphs can be recovered from drill cuttings. Palynomorphs also are found in both marine and nonmarine rocks and can be used for correlation between facies. In this paper, stratigraphic ranges of selected Cretaceous marine and nonmarine palynomorphs in previously designated reference sections in Fossil Basin, Wyoming, are correlated with the occurrence of ammonities and other zone fossils in the same sections. These correlations can be related to known isotopic ages, and they contribute to the calibration of palynomorph ranges in the Cretaceous of the Western Interior.« less

Capturing 3D resistivity of semi-arid karstic subsurface in varying moisture conditions using a wireless sensor network

NASA Astrophysics Data System (ADS)

Barnhart, K.; Oden, C. P.

2012-12-01

The dissolution of soluble bedrock results in surface and subterranean karst channels, which comprise 7-10% of the dry earth's surface. Karst serves as a preferential conduit to focus surface and subsurface water but it is difficult to exploit as a water resource or protect from pollution because of irregular structure and nonlinear hydrodynamic behavior. Geophysical characterization of karst commonly employs resistivity and seismic methods, but difficulties arise due to low resistivity contrast in arid environments and insufficient resolution of complex heterogeneous structures. To help reduce these difficulties, we employ a state-of-the-art wireless geophysical sensor array, which combines low-power radio telemetry and solar energy harvesting to enable long-term in-situ monitoring. The wireless aspect removes topological constraints common with standard wired resistivity equipment, which facilitates better coverage and/or sensor density to help improve aspect ratio and resolution. Continuous in-situ deployment allows data to be recorded according to nature's time scale; measurements are made during infrequent precipitation events which can increase resistivity contrast. The array is coordinated by a smart wireless bridge that continuously monitors local soil moisture content to detect when precipitation occurs, schedules resistivity surveys, and periodically relays data to the cloud via 3G cellular service. Traditional 2/3D gravity and seismic reflection surveys have also been conducted to clarify and corroborate results.

Constraining the Dynamical Formation and the Size of the Primordial Building Blocks for Comet 67P/Churyumov-Gerasimenko Using the CONSERT Observations

NASA Astrophysics Data System (ADS)

Heggy, E.; Palmer, E. M.; Kofman, W. W.; Herique, A.; El Maarry, M. R.

2017-12-01

Rosetta's two-year orbital mission at comet 67P/Churyumov-Gerasimenko significantly improved our understanding of the Radar properties of cometary bodies and how they can be used to constrain the ambiguities associated to the dynamical formation of 67P by setting an upper limit on the size of the comet's initial building blocks using the CONSERT, VIRTIS and OSIRIS observations. We present here in an updated post-rendezvous three-dimensional dielectric, textural and structural model of the comet's surface and subsurface at VHF-, X- and S-band radar frequencies. We assess the radar properties of potential structural heterogeneities observed in the upper meters of the shallow subsurface as well as deeper structures across the comet head. We use CONSERT's bistatic radar sounding measurements of the nucleus `head' interior to constrain the dielectric properties and structure of the interior; VIRTIS' multi-spectral observations to constrain the surface mineralogy and the distribution of water-ice on the surface and the implications of the above on the spatial variability of the surface and shallow subsurface dielectric properties. Surface and shallow subsurface structural elements are derived from the OSIRIS' images of exposed outcrops and pit walls. Our dielectric analysis showing the lack of sufficient dielectric contrast correlated with the lack of signal broadening in the 90-MHz radar echoes observed by CONSERT suggests that the the apparent meter-sized inhomogeneities in the walls of deep pits originally interpreted as cometesimals forming the comet's primordial blocks, could be localized evolutionary features of high centered polygons caused by seasonal modifications to the near-subsurface ice formed through thermal expansion and contraction and may not be continuous through the head. Considering the three-dimensional dielectric variability of 67P as derived from CONSERT, VIRTIS, Arecibo observations and laboratory measurement we set an upper limit on the size of the comet's initial building blocks.

3D Seismic Imaging over a Potential Collapse Structure

NASA Astrophysics Data System (ADS)

Gritto, Roland; O'Connell, Daniel; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

2016-04-01

The Middle-East has seen a recent boom in construction including the planning and development of complete new sub-sections of metropolitan areas. Before planning and construction can commence, however, the development areas need to be investigated to determine their suitability for the planned project. Subsurface parameters such as the type of material (soil/rock), thickness of top soil or rock layers, depth and elastic parameters of basement, for example, comprise important information needed before a decision concerning the suitability of the site for construction can be made. A similar problem arises in environmental impact studies, when subsurface parameters are needed to assess the geological heterogeneity of the subsurface. Environmental impact studies are typically required for each construction project, particularly for the scale of the aforementioned building boom in the Middle East. The current study was conducted in Qatar at the location of a future highway interchange to evaluate a suite of 3D seismic techniques in their effectiveness to interrogate the subsurface for the presence of karst-like collapse structures. The survey comprised an area of approximately 10,000 m2 and consisted of 550 source- and 192 receiver locations. The seismic source was an accelerated weight drop while the geophones consisted of 3-component 10 Hz velocity sensors. At present, we analyzed over 100,000 P-wave phase arrivals and performed high-resolution 3-D tomographic imaging of the shallow subsurface. Furthermore, dispersion analysis of recorded surface waves will be performed to obtain S-wave velocity profiles of the subsurface. Both results, in conjunction with density estimates, will be utilized to determine the elastic moduli of the subsurface rock layers.

The influence of subsurface hydrodynamics on convective precipitation

NASA Astrophysics Data System (ADS)

Rahman, A. S. M. M.; Sulis, M.; Kollet, S. J.

2014-12-01

The terrestrial hydrological cycle comprises complex processes in the subsurface, land surface, and atmosphere, which are connected via complex non-linear feedback mechanisms. The influence of subsurface hydrodynamics on land surface mass and energy fluxes has been the subject of previous studies. Several studies have also investigated the soil moisture-precipitation feedback, neglecting however the connection with groundwater dynamics. The objective of this study is to examine the impact of subsurface hydrodynamics on convective precipitation events via shallow soil moisture and land surface processes. A scale-consistent Terrestrial System Modeling Platform (TerrSysMP) that consists of an atmospheric model (COSMO), a land surface model (CLM), and a three-dimensional variably saturated groundwater-surface water flow model (ParFlow), is used to simulate hourly mass and energy fluxes over days with convective rainfall events over the Rur catchment, Germany. In order to isolate the effect of groundwater dynamics on convective precipitation, two different model configurations with identical initial conditions are considered. The first configuration allows the groundwater table to evolve through time, while a spatially distributed, temporally constant groundwater table is prescribed as a lower boundary condition in the second configuration. The simulation results suggest that groundwater dynamics influence land surface soil moisture, which in turn affects the atmospheric boundary layer (ABL) height by modifying atmospheric thermals. It is demonstrated that because of this sensitivity of ABL height to soil moisture-temperature feedback, the onset and magnitude of convective precipitation is influenced by subsurface hydrodynamics. Thus, the results provide insight into the soil moisture-precipitation feedback including groundwater dynamics in a physically consistent manner by closing the water cycle from aquifers to the atmosphere.

3D mapping of buried rocks by the GPR WISDOM/ExoMars 2020

NASA Astrophysics Data System (ADS)

Herve, Yann; Ciarletti, Valerie; Le Gall, Alice; Quantin, Cathy; Guiffaut, Christophe; Plettemeier, Dirk

2017-04-01

The main objective of ExoMars 2020 is to search for signs of past and/or present life on Mars. Because these signs may be beneath the inhospitable surface of Mars, the ExoMars Rover has on board a suite of instruments aiming at characterizing the subsurface. In particular, the Rover payload includes WISDOM (Water Ice Subsurface Deposits Observation on Mars), a polarimetric ground penetrating radar designed to investigate the shallow subsurface. WISDOM is able to probe down to a depth of few meters with a resolution of few centimeters; its main objective is to provide insights into the geological context of the investigated Martian sites and to determine the most promising location to collect samples for the ExoMars drill. In this paper, we demonstrate the ability of WISDOM to locate buried rocks and to estimate their size distribution. Indeed, the rock distribution is related to the geological processes at play in the past or currently and thus provides clues to understand the geological context of the investigated site. Rocks also represent a hazard for drilling operations that WISDOM is to guide. We use a 3D FDTD code called TEMSI-FD (which takes into account the radiation pattern of the antenna system) to simulate WISDOM operations on a realistic (both in terms of dielectric properties and structure) ground. More specifically, our geoelectrical models of the Martian subsurface take into account realistic values of the complex permittivity relying on published measurements performed in laboratory on Martian analogues. Further, different distributions of buried rocks are considered based on the size-frequency distribution observed at the Mars Pathfinder landing site and on Oxia Planum, the landing site currently selected for ExoMars 2020. We will describe the algorithm we developed to automatically detect the signature of the buried rocks on radargrams. The radargrams are obtained simulating WISDOM operations along parallel and perpendicular profiles as planned for the ExoMars mission. Our ultimate goal is to show that WISDOM observations can be used to build a 3D map of the subsurface. We will also present experimental data obtained with a prototype of WISDOM to test our method.

Deconstructing the shallow internal structure of the Moon using GRAIL gravity and LOLA topography

NASA Astrophysics Data System (ADS)

Zuber, M. T.

2015-12-01

Globally-distributed, high-resolution gravity and topography observations of the Moon from the Gravity Recovery and Interior Laboratory (GRAIL) mission and Lunar Orbiter Laser Altimeter (LOLA) instrument aboard the Lunar Reconnaissance Orbiter (LRO) spacecraft afford the unprecedented opportunity to explore the shallow internal structure of the Moon. Gravity and topography can be combined to produce Bouguer gravity that reveals the distribution of mass in the subsurface, with high degrees in the spherical harmonic expansion of the Bouguer anomalies sensitive to shallowest structure. For isolated regions of the lunar highlands and several basins we have deconstructed the gravity field and mapped the subsurface distribution of density anomalies. While specified spherical harmonic degree ranges can be used to estimate contributions at different depths, such analyses require considerable caution in interpretation. A comparison of filtered Bouguer gravity with forward models of disk masses with plausible densities illustrates the interdependencies of the gravitational power of density anomalies with depth and spatial scale. The results have implications regarding the limits of interpretation of lunar subsurface structure.

Influence of Applying Additional Forcing Fans for the Air Distribution in Ventilation Network

NASA Astrophysics Data System (ADS)

Szlązak, Nikodem; Obracaj, Dariusz; Korzec, Marek

2016-09-01

Mining progress in underground mines cause the ongoing movement of working areas. Consequently, it becomes necessary to adapt the ventilation network of a mine to direct airflow into newly-opened districts. For economic reasons, opening new fields is often achieved via underground workings. Length of primary intake and return routes increases and also increases the total resistance of a complex ventilation network. The development of a subsurface structure can make it necessary to change the air distribution in a ventilation network. Increasing airflow into newly-opened districts is necessary. In mines where extraction does not entail gas-related hazards, there is possibility of implementing a push-pull ventilation system in order to supplement airflows to newly developed mining fields. This is achieved by installing subsurface fan stations with forcing fans at the bottom of downcast shaft. In push-pull systems with multiple main fans, it is vital to select forcing fans with characteristic curves matching those of the existing exhaust fans to prevent undesirable mutual interaction. In complex ventilation networks it is necessary to calculate distribution of airflow (especially in networks with a large number of installed fans). In the article the influence of applying additional forcing fans for the air distribution in ventilation network for underground mine were considered. There are also analysed the extent of overpressure caused by the additional forcing fan in branches of the ventilation network (the operating range of additional forcing fan). Possibilities of increasing airflow rate in working areas were conducted.

Structural, electronic and optical properties of CO adsorbed on the defective anatase TiO2 (101) surface; a DFT study

NASA Astrophysics Data System (ADS)

Rafique, Muhammad; Shuai, Yong; Hassan, Muhammad

2017-08-01

This paper illustrates the study of stable structural, electronic and optical properties of carbon mono oxide (CO) molecule adsorbed on pure anatase TiO2 (101) surface and CO molecule adsorbed on defective anatase TiO2 (101) surface containing oxygen (O) atom subsurface vacancy using first-principles study calculations based on density functional theory (DFT) method. A foreign molecule CO was added in the interstitial space of anatase TiO2 (101) surface. It was observed that, adsorption of CO molecule is not favorable on pure anatase TiO2 (101) surface, however adsorption process is improved when subsurface contains O atom vacancy defect. In case of anatase TiO2 (101) surface containing subsurface vacancy, adsorption process is exothermic, resulting in stable structures. The adsorption energies calculated for CO molecules adsorbed at O2c site, at defect site and at Ti5c site of anatase surface containing subsurface O vacancy are 0.16 eV (at O2c), 0.32 eV (at defect site) and 0.43 eV (at Ti5c) site. DOS and PDOS plots are calculated for all the structures. Results indicated that CO molecule adsorption introduces surface states at the Fermi energy level (EF) as shown in partial density of states (PDOS) plots. The dielectric matrix and absorption coefficient (α) for defective anatase TiO2 (101) surface, CO adsorbed at O2c site, at defect site and at Ti5C site of anatase TiO2 (101) surface containing O atom subsurface vacancy has been calculated within the random phase approximation (RPA) using VASP (Vienna ab-initio simulation package) code. It was observed that upon CO adsorption at defective anatase surface, real and imaginary dielectric function peaks were shifted towards lower energy level and a small absorption peak was observed at 1.1 eV energy level which is not present in case of defective anatase (101) surface. CO adsorption produces a red shift in the absorption spectrum of anatase TiO2 (101) surface containing subsurface O atom vacancy.

West Central Texas. Homework pays off for Originala in Haskell County

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickey, V.

1983-03-01

Originala Petroleum Corp., Fort Worth, is finding Bend Conglomerate and Caddo oil in NW Haskell County, Texas. The most encouraging find to date is the company's No. 1 June L. White, which potentialed in Sept. 1981 for 493 bopd from perforations in the Caddo at 5638-60 ft. This discovery, along with promising Bend Conglomerate drill stem test and log shows in other wells in the region, support continued exploration efforts in this geologically complex province. The key to overcoming the exploration challenges in NW. Haskell County is to depend primarily upon seismic data to give structural control. Accurate seismic interpretationmore » is only a part of the preparation, and is integrated with other geologic data-collecting methods such as gravity and structural mapping based solely on subsurface control.« less

Subsurface Investigation using 2D Resistivity and Ground Penetrating Radar at Teluk Kumbar, Penang

NASA Astrophysics Data System (ADS)

Teoh, YJ; Bruka, MA; Idris, NM; Ismail, NA; Muztaza, NM

2018-04-01

The objective of this study is to determine the structure and condition of the subsurface by using 2D resistivity and Ground Penetrating Radar (GPR) methods. The study was conducted at SK Sungai Batu, Teluk Kumbar, Penang Island. For 2D resistivity method, Wenner-Schlumberger array was used while for GPR, 250 MHz antenna was used at the site. The survey consists of 200m length survey line. GPR result shows that there is high intensity of EM. 2D resistivity result shows that the low resistivity region (200 Ωm to 340 Ωm) appears to be at the centre of the survey line from depth 7 m to 13 m. Meanwhile, the higher resistivity region (4000 Ωm to 6000 Ωm) may indicate the bedrock structure of the subsurface, which is the granitic rock. This region is bedrock which rested at depth 14 m and below. In conclusion, data obtained from GPR and 2D resistivity methods can be easily correlated to determine the features of the subsurface.

Conceptual Model Evaluation using Advanced Parameter Estimation Techniques with Heat as a Tracer

NASA Astrophysics Data System (ADS)

Naranjo, R. C.; Morway, E. D.; Healy, R. W.

2016-12-01

Temperature measurements made at multiple depths beneath the sediment-water interface has proven useful for estimating seepage rates from surface-water channels and corresponding subsurface flow direction. Commonly, parsimonious zonal representations of the subsurface structure are defined a priori by interpretation of temperature envelopes, slug tests or analysis of soil cores. However, combining multiple observations into a single zone may limit the inverse model solution and does not take full advantage of the information content within the measured data. Further, simulating the correct thermal gradient, flow paths, and transient behavior of solutes may be biased by inadequacies in the spatial description of subsurface hydraulic properties. The use of pilot points in PEST offers a more sophisticated approach to estimate the structure of subsurface heterogeneity. This presentation evaluates seepage estimation in a cross-sectional model of a trapezoidal canal with intermittent flow representing four typical sedimentary environments. The recent improvements in heat as a tracer measurement techniques (i.e. multi-depth temperature probe) along with use of modern calibration techniques (i.e., pilot points) provides opportunities for improved calibration of flow models, and, subsequently, improved model predictions.

Form and function in hillslope hydrology: in situ imaging and characterization of flow-relevant structures

NASA Astrophysics Data System (ADS)

Jackisch, Conrad; Angermann, Lisa; Allroggen, Niklas; Sprenger, Matthias; Blume, Theresa; Tronicke, Jens; Zehe, Erwin

2017-07-01

The study deals with the identification and characterization of rapid subsurface flow structures through pedo- and geo-physical measurements and irrigation experiments at the point, plot and hillslope scale. Our investigation of flow-relevant structures and hydrological responses refers to the general interplay of form and function, respectively. To obtain a holistic picture of the subsurface, a large set of different laboratory, exploratory and experimental methods was used at the different scales. For exploration these methods included drilled soil core profiles, in situ measurements of infiltration capacity and saturated hydraulic conductivity, and laboratory analyses of soil water retention and saturated hydraulic conductivity. The irrigation experiments at the plot scale were monitored through a combination of dye tracer, salt tracer, soil moisture dynamics, and 3-D time-lapse ground penetrating radar (GPR) methods. At the hillslope scale the subsurface was explored by a 3-D GPR survey. A natural storm event and an irrigation experiment were monitored by a dense network of soil moisture observations and a cascade of 2-D time-lapse GPR trenches. We show that the shift between activated and non-activated state of the flow paths is needed to distinguish structures from overall heterogeneity. Pedo-physical analyses of point-scale samples are the basis for sub-scale structure inference. At the plot and hillslope scale 3-D and 2-D time-lapse GPR applications are successfully employed as non-invasive means to image subsurface response patterns and to identify flow-relevant paths. Tracer recovery and soil water responses from irrigation experiments deliver a consistent estimate of response velocities. The combined observation of form and function under active conditions provides the means to localize and characterize the structures (this study) and the hydrological processes (companion study Angermann et al., 2017, this issue).

Geometry and controls on the development of igneous sill-related forced folds: 2D seismic reflection case study from offshore Southern Australia

NASA Astrophysics Data System (ADS)

Jackson, Christopher; Schofield, Nick; Magee, Craig; Golenkov, Bogdan

2017-04-01

Emplacement of magma in the shallow subsurface can result in the development of dome-shaped folds at the Earth's surface. These so-called 'forced folds' have been described in the field and in subsurface datasets, although the exact geometry of the folds and the nature of their relationship to underlying sills remains unclear and, in some cases, controversial. As a result, the utility of these features in tracking the subsurface movement of magma, and predicting the potential size and location of potentially hazardous volcanic eruptions, is uncertain. Here we use high-quality, 2D seismic reflection and borehole data from the Ceduna sub-basin, offshore southern Australia to describe the structure and infer the evolution of igneous sill-related forced folds in the Bight Basin Igneous Complex (BBIC). We mapped 33 igneous sills, which were emplaced 200-1500 m below the palaeo-seabed in an Upper Cretaceous, coal-bearing, predominantly coastal-plain succession. The intrusions, which are expressed as packages of high-amplitude reflections, are 32-250 m thick and 7-19 km in diameter. They are overlain by dome-shaped folds, which are up to 17 km wide and display up to 210 m of relief. The edges of these folds coincide with the margins of the underlying sills and the folds display the greatest relief where the underlying sills are thickest; the folds are therefore interpreted as forced folds that formed in response to emplacement of magma in the shallow subsurface. The folds are onlapped by Lutetian (middle Eocene) strata, indicating they formed and the intrusions were emplaced during the latest Ypresian (c. 48 Ma). We demonstrate that fold amplitude is typically less than sill thickness even for sills with very large diameter-to-depth ratios, suggesting that pure elastic bending (forced folding) of the overburden is not the only process accommodating magma emplacement, and that supra-sill compaction may be important even at relatively shallow depths. Based on the observation that the sills intruded a shallowly-buried succession, the discrepancy between fold amplitude and sill thickness may reflect loss of host rock volume by fluidisation and pore fluid expulsion from poorly-lithified, water-rich beds. This study indicates that host rock composition, emplacement depth and deformation mechanisms are important controls on the style of deformation that occurs during intrusive igneous activity, and that forced fold amplitude may not always reflect the thickness of an underlying igneous intrusion. In addition, the results of this study suggest that physical and numerical models need to model more complex host rock stratigraphies and rheologies if they wish to capture the full range of deformation mechanisms that occur during magma emplacement in the Earth's shallow subsurface.

Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

NASA Astrophysics Data System (ADS)

Annewandter, R.

2013-12-01

The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced soil gas sampling during On-Site inspections. Gas transport has been widely studied with different numerical codes. However, gas transport of all radioxenons in the post-detonation regime and their possible fractionation is still neglected in the open literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radioxenons, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different diffusivities due to mass differences between the radioxenons. A previous study showed surface arrival time of a chemically inert gaseous tracer is affected by its diffusivity. They observed detectable amount for SF6 50 days after detonation and 375 days for He-3. They predict 50 and 80 days for Xe-133 and Ar-37 respectively. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations , fracture propagation in fractured, porous media, Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite volume method. The parabolic and hyperbolic problem can be solved separately using the operator-splitting method (Implicit Pressure Explicit Saturation, IMPES). The resulting system of linear equations is solved by the algebraic multigrid library SAMG, developed at the Fraunhofer Institute for Algorithms and Scientific Computing. CSMP++ is developed at Montan University of Leoben, ETH Zuerich, Imperial College London and Heriot-Watt University in Edinburgh. To date, there has been no research investigating how subsurface transport impacts isotope activity ratios. The isotopic activity ratio method can be used to discriminate between civil release or nuclear explosion sources. This study examines possible fractionation of Xe-135, Xe-133m, Xe-133, Xe-131m during barometric pumping-driven subsurface migration, which can affect surface arrival times and isotopic activity ratios. Surface arrival times for the Noble gases Kr-81, Kr-85 and Ar-39 are also calculated.

Assessment of groundwater potentiality using geophysical techniques in Wadi Allaqi basin, Eastern Desert, Egypt - Case study

NASA Astrophysics Data System (ADS)

Helaly, Ahmad Sobhy

2017-12-01

Electrical resistivity surveying has been carried out for the determination of the thickness and resistivity of layered media in Wadi Allaqi, Eastern Desert, Egypt. That is widely used geophysical tool for the purpose of assessing the groundwater potential and siting the best locations for boreholes in the unconfined Nubian Sandstone aquifers within the study area. This has been done using thirteen 1D Vertical Electrical Sounding (VES) surveys. 1D-VES surveys provide only layered model structures for the subsurface and do not provide comprehensive information for interpreting the structure and extent of subsurface hydro-geological features. The integration of two-dimensional (2D) geophysical techniques for groundwater prospecting has been done to provide a more detailed identification for the subsurface hydro-geological features from which potential sites for successful borehole locations are recognized. In addition, five magnetic profiles were measured for basement depth determination, expected geological structures and thickness of sedimentary succession that could include some basins suitable for groundwater accumulation as groundwater aquifers.

Subsurface imaging and cell refractometry using quantitative phase/ shear-force feedback microscopy

NASA Astrophysics Data System (ADS)

Edward, Kert; Farahi, Faramarz

2009-10-01

Over the last few years, several novel quantitative phase imaging techniques have been developed for the study of biological cells. However, many of these techniques are encumbered by inherent limitations including 2π phase ambiguities and diffraction limited spatial resolution. In addition, subsurface information in the phase data is not exploited. We hereby present a novel quantitative phase imaging system without 2 π ambiguities, which also allows for subsurface imaging and cell refractometry studies. This is accomplished by utilizing simultaneously obtained shear-force topography information. We will demonstrate how the quantitative phase and topography data can be used for subsurface and cell refractometry analysis and will present results for a fabricated structure and a malaria infected red blood cell.

Integrated interpretation of geophysical data of the Paleozoic structure in the northwestern part of the Siljan Ring impact crater, central Sweden

NASA Astrophysics Data System (ADS)

Muhamad, Harbe; Juhlin, Christopher; Malehmir, Alireza; Sopher, Daniel

2018-01-01

The Siljan Ring impact structure is the largest known impact structure in Europe and is Late Devonian in age. It contains a central uplift that is about 20-30 km in diameter and is surrounded by a ring-shaped depression. The Siljan area is one of the few areas in Sweden where the Paleozoic sequence has not been completely eroded, making it an important location for investigation of the geological and tectonic history of Baltica during the Paleozoic. The Paleozoic strata in this area also provide insight into the complex deformation processes associated with the impact. In this study we focus on the northwestern part of the Siljan Ring, close to the town of Orsa, with the main objective of characterizing the subsurface Paleozoic succession and uppermost Precambrian crystalline rocks along a series of seismic reflection profiles, some of which have not previously been published. We combine these seismic data with gravity and magnetic data and seismic traveltime tomography results to produce an integrated interpretation of the subsurface in the area. Our interpretation shows that the Paleozoic sequence in this area is of a relatively constant thickness, with a total thickness typically between 300 and 500 m. Faulting appears to be predominantly extensional, which we interpret to have occurred during the modification stage of the impact. Furthermore, based on the geophysical data in this area, we interpret that the impact related deformation to differ in magnitude and style from other parts of the Siljan Ring.

Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto.

PubMed

Nimmo, F; Hamilton, D P; McKinnon, W B; Schenk, P M; Binzel, R P; Bierson, C J; Beyer, R A; Moore, J M; Stern, S A; Weaver, H A; Olkin, C B; Young, L A; Smith, K E

2016-12-01

The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto's tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin's present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.

Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto

NASA Astrophysics Data System (ADS)

Nimmo, F.; Hamilton, D. P.; McKinnon, W. B.; Schenk, P. M.; Binzel, R. P.; Bierson, C. J.; Beyer, R. A.; Moore, J. M.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Young, L. A.; Smith, K. E.; Moore, J. M.; McKinnon, W. B.; Spencer, J. R.; Beyer, R.; Binzel, R. P.; Buie, M.; Buratti, B.; Cheng, A.; Cruikshank, D.; Ore, C. Dalle; Earle, A.; Gladstone, R.; Grundy, W.; Howard, A. D.; Lauer, T.; Linscott, I.; Nimmo, F.; Parker, J.; Porter, S.; Reitsema, H.; Reuter, D.; Roberts, J. H.; Robbins, S.; Schenk, P. M.; Showalter, M.; Singer, K.; Strobel, D.; Summers, M.; Tyler, L.; White, O. L.; Umurhan, O. M.; Banks, M.; Barnouin, O.; Bray, V.; Carcich, B.; Chaikin, A.; Chavez, C.; Conrad, C.; Hamilton, D. P.; Howett, C.; Hofgartner, J.; Kammer, J.; Lisse, C.; Marcotte, A.; Parker, A.; Retherford, K.; Saina, M.; Runyon, K.; Schindhelm, E.; Stansberry, J.; Steffl, A.; Stryk, T.; Throop, H.; Tsang, C.; Verbiscer, A.; Winters, H.; Zangari, A.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Young, L. A.; Smith, K. E.

2016-12-01

The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto’s tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin’s present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.

Vanguard - a proposed European astrobiology experiment on Mars

NASA Astrophysics Data System (ADS)

Ellery, A. A.; Cockell, C. S.; Edwards, H. G. M.; Dickensheets, D. L.; Welch, C. S.

2002-07-01

We propose a new type of robotic mission for the exploration of Mars. This mission is called Vanguard and represents the fruits of a collaboration that is both international and multi-disciplinary. Vanguard is designed for sub-surface penetration and investigation using remote instruments and unlike previous robotic architectures it offers the opportunity for multiple subsurface site analysis using three moles. The moles increase the probability that a subsurface signature of life can be found and by accomplishing subsurface analysis across a transect, the statistical rigour of Martian scientific exploration would be improved. There is no provision for returning samples to the surface for analysis by a gas-chromatograph/mass-spectrometer (GCMS) this minimizes the complexity invoked by sophisticated robotic overheads. The primary scientific instruments to be deployed are the Raman spectrometer, infrared spectrometer and laser-induced breakdown spectroscope the Raman spectrometer in particular is discussed. We concentrate primarily on the scientific rationale for the Vanguard mission proposal. The Vanguard mission proposal represents a logical opportunity for extending European robotic missions to Mars.

Imaging near-subsurface subrosion structures and faults using SH-wave reflection seismics

NASA Astrophysics Data System (ADS)

Wadas, Sonja; Polom, Ulrich; Buness, Hermann; Krawczyk, Charlotte

2016-04-01

Subrosion is a term for underground leaching of soluble rocks and is a global phenomenon. It involves dissolution of evaporites due to the presence of unsaturated water, fractures and faults. Fractures and faults are pathways for water to circulate and to generate subsurface cavities. Depending on the leached material and the parameters of the generation process, especially the dissolution rate, different kinds of subrosion structures evolve in the subsurface. The two end members are collapse and depression structures. Subrosion is a natural process, but it can be enhanced by anthropogenic factors like manipulation of the aquifer system and groundwater flow and by e.g. extraction of saline water. The formation of sinkholes and depressions are a dangerous geohazard, especially if they occur in urban areas, which often leads to building and infrastructural damage and life-threatening situations. For this reason investigations of the processes that induce subrosion and a detailed analysis of the resulting structures are of importance. To develop a comprehensive model of near-subsurface subrosion structures, reflection seismics is one of the methods used by the Leibniz Institute for Applied Geophysics. The study area is located in the city of Bad Frankenhausen in northern Thuringia, Germany. Most of the geological underground of Thuringia is characterized by Permian deposits. Bad Frankenhausen is situated directly south of the Kyffhäuser mountain range at the Kyffhäuser Southern Margin Fault. This major fault is one of the main pathways for the circulating ground- and meteoric waters that leach the Permian deposits, especially the Leine-, Staßfurt- and Werra Formations. 2014 and 2015 eight shear wave reflection seismic profiles were carried out in the urban area of Bad Frankenhausen and three profiles in the countrified surroundings. Altogether ca. 3.6 km were surveyed using a landstreamer as receiver and an electro-dynamic vibrator as source. The surveys were adjusted in able to measure in the medieval center of Bad Frankenhausen. This required special equipment and configuration due to the densely built-up area, the differing ground conditions and the varying topography. The analysis of the seismic sections revealed structures associated with the continuing subrosion of the Permian deposits. The reflection patterns indicate heterogeneous near-surface geology of lateral and vertical variations in forms of discontinuous reflectors, small-scale fractures and faults. The fractures and faults also serve as additional pathways for the circulating water and the deposits are subsiding along these features, resulting in the formation of depression structures in the near-subsurface. Diffractions in the unmigrated sections indicate voids in the subsurface that develop due to the longtime subrosion processes. Besides these structures, variations of the traveltime, absorption and scattering of the seismic waves induced by the subrosion processes are visible.

Biodegradation of crude oil in Arctic subsurface water from the Disko Bay (Greenland) is limited.

PubMed

Scheibye, Katrine; Christensen, Jan H; Johnsen, Anders R

2017-04-01

Biological degradation is the main process for oil degradation in a subsurface oil plume. There is, however, little information on the biodegradation potential of Arctic, marine subsurface environments. We therefore investigated oil biodegradation in microcosms at 2 °C containing Arctic subsurface seawater from the Disko Bay (Greenland) and crude oil at three concentrations of 2.5-10 mg/L. Within 71 days, the total petroleum hydrocarbon concentration decreased only by 18 ± 18% for an initial concentration of 5 mg/L. The saturated alkanes nC13-nC30 and the isoprenoids iC18-iC21 were biodegraded at all concentrations indicating a substantial potential for biodegradation of these compound classes. Polycyclic aromatic compounds (PACs) disappeared from the oil phase, but dissolution was the main process of removal. Analysis of diagnostic ratios indicated almost no PAC biodegradation except for the C1-naphthalenes. To conclude, the marine subsurface microorganisms from the Disko Bay had the potential for biodegradation of n-alkanes and isoprenoids while the metabolically complex and toxic PACs and their alkylated homologs remained almost unchanged. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hillslope characterization in terms of geophysical units based on the joint interpretation of electrical resistivity and seismic velocity data

NASA Astrophysics Data System (ADS)

Feskova, Tatiana; Dietrich, Peter

2015-04-01

Hydrological conditions in a catchment depend on many factors such as climatic, geological, geomorphological, biological and human, which interact with each other and influence water balance in a catchment. This interaction leads to the subordination in the landscape structure, namely the weak elements subordinate to the powerful elements. Thereby, geological and geomorphological factors play an essential role in catchment development and organization. A hillslope consequently can be allocated to one class of the representative units because the important flow processes run at the hillslope. Moreover, a hillslope can be subdivided into stratigraphic subsurface units and significant hillslope areas based on the lithological change of contrasting interfaces. The knowledge of subsurface structures is necessary to understand and predicate complex hydrological processes in a catchment. Geophysical techniques provide a good opportunity to explore the subsurface. A complete geophysical investigation of subsurface in a catchment with difficult environmental conditions never will be achieved because of large time effort in the field, equipment logistic, and ambiguity in the data interpretation. The case study demonstrates how a catchment can be investigated using geophysical methods in an effective manner in terms of characterization of representative units with respect to a functional role in the catchment. This case study aims to develop combined resistivity and seismic velocity hillslope subsurface models for the distinction of representative functional units. In order to identify the contrasting interfaces of the hillslope, to localize significant hillslope areas, and to address the ambiguity in the geophysical data interpretation, the case study combined resistivity surveys (vertical electrical soundings and electrical resistivity tomography) with refraction seismic method, and conducted these measurements at one single profile along the hillslope transect and perpendicular to this transect. The measurements along the hillslope transect deliver the two-dimensional hillslope section of resistivity and seismic velocity distribution with contrasting stratigraphic interfaces, whereas the measurements perpendicular to the hillslope transect obtained from vertical electrical soundings survey localize significant hillslope areas indicating existence of two-dimensional features in the subsurface. To demonstrate the suitability of the suggested approach, resistivity and refraction seismic measurements were carried out at the forested gently inclined hillslope in the Weierbach catchment, which belongs to the hydrological observatory Attert Basin locating in the mid-western part of the Grand-Duchy of Luxembourg. This hillslope is characterized by Pleistocene periglacial slope deposits, which plays an important role in the ecosystem functioning. The obtained resistivity and seismic hillslope models of the Weierbech catchment complement well one another. The hillslope models identify three significant hillslope areas along the hillslope called as elementary functional units, and four electrical vertical stratigraphic units and two seismic vertical stratigraphic units that agree with lithological stratigraphy of this study site. In conclusions, the suggested geophysical approach is suitable to characterise a hillslope as the representative unit only at a single transect in the efficient manner in contrast to the expensive 3D-measurements.

Elements of complexity in subsurface modeling, exemplified with three case studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freedman, Vicky L.; Truex, Michael J.; Rockhold, Mark

2017-04-03

There are complexity elements to consider when applying subsurface flow and transport models to support environmental analyses. Modelers balance the benefits and costs of modeling along the spectrum of complexity, taking into account the attributes of more simple models (e.g., lower cost, faster execution, easier to explain, less mechanistic) and the attributes of more complex models (higher cost, slower execution, harder to explain, more mechanistic and technically defensible). In this paper, modeling complexity is examined with respect to considering this balance. The discussion of modeling complexity is organized into three primary elements: 1) modeling approach, 2) description of process, andmore » 3) description of heterogeneity. Three examples are used to examine these complexity elements. Two of the examples use simulations generated from a complex model to develop simpler models for efficient use in model applications. The first example is designed to support performance evaluation of soil vapor extraction remediation in terms of groundwater protection. The second example investigates the importance of simulating different categories of geochemical reactions for carbon sequestration and selecting appropriate simplifications for use in evaluating sequestration scenarios. In the third example, the modeling history for a uranium-contaminated site demonstrates that conservative parameter estimates were inadequate surrogates for complex, critical processes and there is discussion on the selection of more appropriate model complexity for this application. All three examples highlight how complexity considerations are essential to create scientifically defensible models that achieve a balance between model simplification and complexity.« less

Elements of complexity in subsurface modeling, exemplified with three case studies

NASA Astrophysics Data System (ADS)

Freedman, Vicky L.; Truex, Michael J.; Rockhold, Mark L.; Bacon, Diana H.; Freshley, Mark D.; Wellman, Dawn M.

2017-09-01

There are complexity elements to consider when applying subsurface flow and transport models to support environmental analyses. Modelers balance the benefits and costs of modeling along the spectrum of complexity, taking into account the attributes of more simple models (e.g., lower cost, faster execution, easier to explain, less mechanistic) and the attributes of more complex models (higher cost, slower execution, harder to explain, more mechanistic and technically defensible). In this report, modeling complexity is examined with respect to considering this balance. The discussion of modeling complexity is organized into three primary elements: (1) modeling approach, (2) description of process, and (3) description of heterogeneity. Three examples are used to examine these complexity elements. Two of the examples use simulations generated from a complex model to develop simpler models for efficient use in model applications. The first example is designed to support performance evaluation of soil-vapor-extraction remediation in terms of groundwater protection. The second example investigates the importance of simulating different categories of geochemical reactions for carbon sequestration and selecting appropriate simplifications for use in evaluating sequestration scenarios. In the third example, the modeling history for a uranium-contaminated site demonstrates that conservative parameter estimates were inadequate surrogates for complex, critical processes and there is discussion on the selection of more appropriate model complexity for this application. All three examples highlight how complexity considerations are essential to create scientifically defensible models that achieve a balance between model simplification and complexity.

Paleomagnetic correlation of basalt flows in selected coreholes near the Advanced Test Reactor Complex, the Idaho Nuclear Technology and Engineering Center, and along the southern boundary, Idaho National Laboratory, Idaho

USGS Publications Warehouse

Hodges, Mary K.V.; Champion, Duane E.

2016-10-03

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, used paleomagnetic data from 18 coreholes to construct three cross sections of subsurface basalt flows in the southern part of the Idaho National Laboratory (INL). These cross sections, containing descriptions of the subsurface horizontal and vertical distribution of basalt flows and sediment layers, will be used in geological studies, and to construct numerical models of groundwater flow and contaminant transport.Subsurface cross sections were used to correlate surface vents to their subsurface flows intersected by coreholes, to correlate subsurface flows between coreholes, and to identify possible subsurface vent locations of subsurface flows. Correlations were identified by average paleomagnetic inclinations of flows, and depth from land surface in coreholes, normalized to the North American Datum of 1927. Paleomagnetic data were combined, in some cases, with other data, such as radiometric ages of flows. Possible vent locations of buried basalt flows were identified by determining the location of the maximum thickness of flows penetrated by more than one corehole.Flows from the surface volcanic vents Quaking Aspen Butte, Vent 5206, Mid Butte, Lavatoo Butte, Crater Butte, Pond Butte, Vent 5350, Vent 5252, Tin Cup Butte, Vent 4959, Vent 5119, and AEC Butte are found in coreholes, and were correlated to the surface vents by matching their paleomagnetic inclinations, and in some cases, their stratigraphic positions.Some subsurface basalt flows that do not correlate to surface vents, do correlate over several coreholes, and may correlate to buried vents. Subsurface flows which correlate across several coreholes, but not to a surface vent include the D3 flow, the Big Lost flow, the CFA buried vent flow, the Early, Middle, and Late Basal Brunhes flows, the South Late Matuyama flow, the Matuyama flow, and the Jaramillo flow. The location of vents buried in the subsurface by younger basalt flows can be inferred if their flows are penetrated by several coreholes, by tracing the flows in the subsurface, and determining where the greatest thickness occurs.

Investigating the subsurface connection beneath Cerro Negro volcano and the El Hoyo Complex, Nicaragua

NASA Astrophysics Data System (ADS)

Venugopal, Swetha; Moune, Séverine; Williams-Jones, Glyn

2016-10-01

Cerro Negro, the youngest volcano along the Central American Volcanic Belt (CAVB), is a polygenetic cinder cone with relatively frequent basaltic eruptions. The neighbouring El Hoyo complex, of which Las Pilas is the dominant edifice, is a much larger and older complex with milder and less frequent eruptions. Previous studies have suggested a deep link beneath these two closely spaced volcanoes (McKnight, 1995; MacQueen, 2013). Melt inclusions were collected from various tephra samples in order to determine whether a connection exists and to delineate the features of this link. Major, volatile, and trace elemental compositions reveal a distinct geochemical continuum with Cerro Negro defining the primitive endmember and El Hoyo representing the evolved endmember. Magmatic conditions at the time of melt inclusion entrapment were estimated with major and volatile contents: 2.4 kbar and 1170 °C for Cerro Negro melts and 1.3 kbar and 1130 °C for El Hoyo melts with an overall oxygen fugacity at the NNO buffer. Trace element contents are distinct and suggest Cerro Negro magmas fractionally crystallise while El Hoyo magmas are a mix between primitive Cerro Negro melts and residual and evolved El Hoyo magma. Modelling of end member compositions with alphaMELTS confirms the unique nature of El Hoyo magmas as resulting from incremental mixing between Cerro Negro and residual evolved magma at 4 km depth. Combining all available literature data, this study presents a model of the interconnected subsurface plumbing system. This model considers the modern day analogue of the Lemptégy cinder cones in Massif Central, France and incorporates structurally controlled dykes. The main implications of this study are the classification of Cerro Negro as the newest conduit within the El Hoyo Complex as well as the potential re-activation of the El Hoyo edifice.

Linking deposit morphology and clogging in subsurface remediation: Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mays, David C.

2013-12-11

Groundwater is a crucial resource for water supply, especially in arid and semiarid areas of the United States west of the 100th meridian. Accordingly, remediation of contaminated groundwater is an important application of science and technology, particularly for the U.S. Department of Energy (DOE), which oversees a number of groundwater remediation sites from Cold War era mining. Groundwater remediation is complex, because it depends on identifying, locating, and treating contaminants in the subsurface, where remediation reactions depend on interacting geological, hydrological, geochemical, and microbiological factors. Within this context, permeability is a fundamental concept, because it controls the rates and pathwaysmore » of groundwater flow. Colloid science is intimately related to permeability, because when colloids are present (particles with equivalent diameters between 1 nanometer and 10 micrometers), changes in hydrological or geochemical conditions can trigger a detrimental reduction in permeability called clogging. Accordingly, clogging is a major concern in groundwater remediation. Several lines of evidence suggest that clogging by colloids depends on (1) colloid deposition, and (2) deposit morphology, that is, the structure of colloid deposits, which can be quantified as a fractal dimension. This report describes research, performed under a 2-year, exploratory grant from the DOE’s Subsurface Biogeochemical Research (SBR) program. This research employed a novel laboratory technique to simultaneously measure flow, colloid deposition, deposit morphology, and permeability in a flow cell, and also collected field samples from wells at the DOE’s Old Rifle remediation site. Field results indicate that suspended solids at the Old Rifle site have fractal structures. Laboratory results indicate that clogging is associated with colloid deposits with smaller fractal dimensions, in accordance with previous studies on initially clean granular media. Preliminary modeling has identified the deposit radius of gyration as a candidate variable to account for clogging as a function of (1) colloid accumulation and (2) deposit morphology.« less

Quantifying shallow subsurface water and heat dynamics using coupled hydrological-thermal-geophysical inversion

DOE PAGES

Tran, Anh Phuong; Dafflon, Baptiste; Hubbard, Susan S.; ...

2016-04-25

Improving our ability to estimate the parameters that control water and heat fluxes in the shallow subsurface is particularly important due to their strong control on recharge, evaporation and biogeochemical processes. The objectives of this study are to develop and test a new inversion scheme to simultaneously estimate subsurface hydrological, thermal and petrophysical parameters using hydrological, thermal and electrical resistivity tomography (ERT) data. The inversion scheme-which is based on a nonisothermal, multiphase hydrological model-provides the desired subsurface property estimates in high spatiotemporal resolution. A particularly novel aspect of the inversion scheme is the explicit incorporation of the dependence of themore » subsurface electrical resistivity on both moisture and temperature. The scheme was applied to synthetic case studies, as well as to real datasets that were autonomously collected at a biogeochemical field study site in Rifle, Colorado. At the Rifle site, the coupled hydrological-thermal-geophysical inversion approach well predicted the matric potential, temperature and apparent resistivity with the Nash-Sutcliffe efficiency criterion greater than 0.92. Synthetic studies found that neglecting the subsurface temperature variability, and its effect on the electrical resistivity in the hydrogeophysical inversion, may lead to an incorrect estimation of the hydrological parameters. The approach is expected to be especially useful for the increasing number of studies that are taking advantage of autonomously collected ERT and soil measurements to explore complex terrestrial system dynamics.« less

Optical method and apparatus for detection of surface and near-subsurface defects in dense ceramics

DOEpatents

Ellingson, W.A.; Brada, M.P.

1995-06-20

A laser is used in a non-destructive manner to detect surface and near-subsurface defects in dense ceramics and particularly in ceramic bodies with complex shapes such as ceramic bearings, turbine blades, races, and the like. The laser`s wavelength is selected based upon the composition of the ceramic sample and the laser can be directed on the sample while the sample is static or in dynamic rotate or translate motion. Light is scattered off surface and subsurface defects using a preselected polarization. The change in polarization angle is used to select the depth and characteristics of surface/subsurface defects. The scattered light is detected by an optical train consisting of a charge coupled device (CCD), or vidicon, television camera which, in turn, is coupled to a video monitor and a computer for digitizing the image. An analyzing polarizer in the optical train allows scattered light at a given polarization angle to be observed for enhancing sensitivity to either surface or near-subsurface defects. Application of digital image processing allows subtraction of digitized images in near real-time providing enhanced sensitivity to subsurface defects. Storing known ``feature masks`` of identified defects in the computer and comparing the detected scatter pattern (Fourier images) with the stored feature masks allows for automatic classification of detected defects. 29 figs.

The Guaymas Basin Hiking Guide to Hydrothermal Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface Hydrothermal Circulation

PubMed Central

Teske, Andreas; de Beer, Dirk; McKay, Luke J.; Tivey, Margaret K.; Biddle, Jennifer F.; Hoer, Daniel; Lloyd, Karen G.; Lever, Mark A.; Røy, Hans; Albert, Daniel B.; Mendlovitz, Howard P.; MacGregor, Barbara J.

2016-01-01

The hydrothermal mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview, we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region. PMID:26925032

Denitrifying Bacteria from the Genus Rhodanobacter Dominate Bacterial Communities in the Highly Contaminated Subsurface of a Nuclear Legacy Waste Site

PubMed Central

Green, Stefan J.; Prakash, Om; Jasrotia, Puja; Overholt, Will A.; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M.; Watson, David B.; Schadt, Christopher W.; Brooks, Scott C.

2012-01-01

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of Rhodanobacter bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment. PMID:22179233

Using the Subsurface Soil Sounding Radar for Investigating the Structure and Total Electron Content of the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Smirnov, V. M.; Yushkova, O. V.; Marchuk, V. N.

2018-05-01

The possibilities of using the Martian soil subsurface sounding radar for investigating the structure of the plasma shell surrounding the planet have been considered. Based on the numerical modeling results and actual soil sounding data, it has been shown that the soil sounding mode of the radio-locating MARSIS radar can be used to assess the structure of the Martian ionosphere. As the emitted signals pass to the planet's surface, it is possible to use the reflected signals to estimate the total electron content of the Martian ionosphere along the flight track of the spacecraft.

THE DOE COMPLEX-WIDE VADOSE ZONE SCIENCE AND TECHNOLOGY ROADMAP: CHARACTERIZATION MODELING AND SIMULATION OF SUBSURFACE CONTAMINANT FATE AND TRANSPORT

EPA Science Inventory

The Idaho National Engineering & Environmental Lab (INEEL) was charged by DOE EM to develop a complex-wide science and technology roadmap for the characterization, modeling and simulation of the fate and transport of contamination in the vadose zone. Various types of hazardous, r...

Glass sample characterization

NASA Technical Reports Server (NTRS)

Ahmad, Anees

1990-01-01

The development of in-house integrated optical performance modelling capability at MSFC is described. This performance model will take into account the effects of structural and thermal distortions, as well as metrology errors in optical surfaces to predict the performance of large an complex optical systems, such as Advanced X-Ray Astrophysics Facility. The necessary hardware and software were identified to implement an integrated optical performance model. A number of design, development, and testing tasks were supported to identify the debonded mirror pad, and rebuilding of the Technology Mirror Assembly. Over 300 samples of Zerodur were prepared in different sizes and shapes for acid etching, coating, and polishing experiments to characterize the subsurface damage and stresses produced by the grinding and polishing operations.

Quantitative assessment of the flow pattern in the southern Arava Valley (Israel) by environmental tracers and a mixing cell model

NASA Astrophysics Data System (ADS)

Adar, E. M.; Rosenthal, E.; Issar, A. S.; Batelaan, O.

1992-08-01

This paper demonstrates the implementation of a novel mathematical model to quantify subsurface inflows from various sources into the arid alluvial basin of the southern Arava Valley divided between Israel and Jordan. The model is based on spatial distribution of environmental tracers and is aimed for use on basins with complex hydrogeological structure and/or with scarce physical hydrologic information. However, a sufficient qualified number of wells and springs are required to allow water sampling for chemical and isotopic analyses. Environmental tracers are used in a multivariable cluster analysis to define potential sources of recharge, and also to delimit homogeneous mixing compartments within the modeled aquifer. Six mixing cells were identified based on 13 constituents. A quantitative assessment of 11 significant subsurface inflows was obtained. Results revealed that the total recharge into the southern Arava basin is around 12.52 × 10 6m3year-1. The major source of inflow into the alluvial aquifer is from the Nubian sandstone aquifer which comprises 65-75% of the total recharge. Only 19-24% of the recharge, but the most important source of fresh water, originates over the eastern Jordanian mountains and alluvial fans.

NIR DLP hyperspectral imaging system for medical applications

NASA Astrophysics Data System (ADS)

Wehner, Eleanor; Thapa, Abhas; Livingston, Edward; Zuzak, Karel

2011-03-01

DLP® hyperspectral reflectance imaging in the visible range has been previously shown to quantify hemoglobin oxygenation in subsurface tissues, 1 mm to 2 mm deep. Extending the spectral range into the near infrared reflects biochemical information from deeper subsurface tissues. Unlike any other illumination method, the digital micro-mirror device, DMD, chip is programmable, allowing the user to actively illuminate with precisely predetermined spectra of illumination with a minimum bandpass of approximately 10 nm. It is possible to construct active spectral-based illumination that includes but is not limited to containing sharp cutoffs to act as filters or forming complex spectra, varying the intensity of light at discrete wavelengths. We have characterized and tested a pure NIR, 760 nm to 1600 nm, DLP hyperspectral reflectance imaging system. In its simplest application, the NIR system can be used to quantify the percentage of water in a subject, enabling edema visualization. It can also be used to map vein structure in a patient in real time. During gall bladder surgery, this system could be invaluable in imaging bile through fatty tissue, aiding surgeons in locating the common bile duct in real time without injecting any contrast agents.

THC-MP: High performance numerical simulation of reactive transport and multiphase flow in porous media

NASA Astrophysics Data System (ADS)

Wei, Xiaohui; Li, Weishan; Tian, Hailong; Li, Hongliang; Xu, Haixiao; Xu, Tianfu

2015-07-01

The numerical simulation of multiphase flow and reactive transport in the porous media on complex subsurface problem is a computationally intensive application. To meet the increasingly computational requirements, this paper presents a parallel computing method and architecture. Derived from TOUGHREACT that is a well-established code for simulating subsurface multi-phase flow and reactive transport problems, we developed a high performance computing THC-MP based on massive parallel computer, which extends greatly on the computational capability for the original code. The domain decomposition method was applied to the coupled numerical computing procedure in the THC-MP. We designed the distributed data structure, implemented the data initialization and exchange between the computing nodes and the core solving module using the hybrid parallel iterative and direct solver. Numerical accuracy of the THC-MP was verified through a CO2 injection-induced reactive transport problem by comparing the results obtained from the parallel computing and sequential computing (original code). Execution efficiency and code scalability were examined through field scale carbon sequestration applications on the multicore cluster. The results demonstrate successfully the enhanced performance using the THC-MP on parallel computing facilities.

Potential for microbial H2 and metal transformations associated with novel bacteria and archaea in deep terrestrial subsurface sediments.

PubMed

Hernsdorf, Alex W; Amano, Yuki; Miyakawa, Kazuya; Ise, Kotaro; Suzuki, Yohey; Anantharaman, Karthik; Probst, Alexander; Burstein, David; Thomas, Brian C; Banfield, Jillian F

2017-08-01

Geological sequestration in deep underground repositories is the prevailing proposed route for radioactive waste disposal. After the disposal of radioactive waste in the subsurface, H 2 may be produced by corrosion of steel and, ultimately, radionuclides will be exposed to the surrounding environment. To evaluate the potential for microbial activities to impact disposal systems, we explored the microbial community structure and metabolic functions of a sediment-hosted ecosystem at the Horonobe Underground Research Laboratory, Hokkaido, Japan. Overall, we found that the ecosystem hosted organisms from diverse lineages, including many from the phyla that lack isolated representatives. The majority of organisms can metabolize H 2 , often via oxidative [NiFe] hydrogenases or electron-bifurcating [FeFe] hydrogenases that enable ferredoxin-based pathways, including the ion motive Rnf complex. Many organisms implicated in H 2 metabolism are also predicted to catalyze carbon, nitrogen, iron and sulfur transformations. Notably, iron-based metabolism is predicted in a novel lineage of Actinobacteria and in a putative methane-oxidizing ANME-2d archaeon. We infer an ecological model that links microorganisms to sediment-derived resources and predict potential impacts of microbial activity on H 2 consumption and retardation of radionuclide migration.

Interpretation of a seismic refraction profile across the Roosevelt Hot Springs, Utah and vicinity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gertson, R.C.; Smith, R.B.

1979-03-01

In April 1977, a seismic refraction profile was recorded across the Milford Valley, the Roosevelt Hot Springs KGRA, and the northern Mineral Mountains in southwestern Utah. Seven shot points were used to provide multiple subsurface seismic refraction coverage along the 30 km east-west profile line. Since an inspection of power spectrums revealed large components of 60 Hz noise on some traces, computer routines were used to low-pass filter all seismograms. Amplitude information was utilized by normalizing all traces that recorded the same blast. Subsurface structural modeling was conducted by means of first arrival P-wave delay-time analysis and ray tracing. Herglotz-Wiechertmore » travel-time inversion was used for the velocity-depth distribution in the Mineral Mountains. The interpretation of the P-wave travel-times suggests that the Milford Valley fill consists of two units with a total thickness of at least 1.8 km. In the vicinity of the Roosevelt KGRA, a thin low velocity alluvial layer covers a basement igneous complex with a velocity of 5.2 km/s. Granite velocities between 3.3 km/s and 4.0 km/s were calculated from the travel-times in the Mineral Mountains.« less

The significance of "geothermal microzonation" for the correct planning of low-grade source geothermal systems

NASA Astrophysics Data System (ADS)

Viccaro, Marco; Pezzino, Antonino; Belfiore, Giuseppe Maria; Campisano, Carlo

2016-04-01

Despite the environmental-friendly energy systems are solar thermal technologies, photovoltaic and wind power, other advantageous technologies exist, although they have not found wide development in countries such as Italy. Given the almost absent environmental impact and the rather favorable cost/benefit ratio, low-enthalpy geothermal systems are, however, likely to be of strategic importance also in Italy during the next years. The importance of geology for a sustainable exploitation of the ground through geothermal systems from low-grade sources is becoming paramount. Specifically, understanding of the lithological characteristics of the subsurface along with structures and textures of rocks is essential for a correct planning of the probe/geo-exchanger field and their associated ground source heat pumps. The complex geology of Eastern Sicily (Southern Italy), which includes volcanic, sedimentary and metamorphic units over limited extension, poses the question of how thermal conductivity of rocks is variable at the scale of restricted areas (even within the same municipality). This is the innovative concept of geothermal microzonation, i.e., how variable is the geothermal potential as a function of geology at the microscale. Some pilot areas have been therefore chosen to test how the geological features of the subsurface can influence the low-enthalpy geothermal potential of an area. Our geologically based evaluation and micro-zonation of the low-grade source geothermal potential of the selected areas have been verified to be fundamental for optimization of all the main components of a low-enthalpy geothermal system. Saving realization costs and limiting the energy consumption through correct sizing of the system are main ambitions to have sustainable development of this technology with intensive utilization of the subsurface. The variegated territory of countries such as Italy implies that these goals can be only reached if, primarily, the geological features of the shallow subsurface (i.e., chemical-physical characteristics of rocks and fluids of the first 100 m below the ground) are appropriately constrained.

High Resolution Stratigraphic Mapping in Complex Terrain: A Comparison of Traditional Remote Sensing Techniques with Unmanned Aerial Vehicle - Structure from Motion Photogrammetry

NASA Astrophysics Data System (ADS)

Nesbit, P. R.; Hugenholtz, C.; Durkin, P.; Hubbard, S. M.; Kucharczyk, M.; Barchyn, T.

2016-12-01

Remote sensing and digital mapping have started to revolutionize geologic mapping in recent years as a result of their realized potential to provide high resolution 3D models of outcrops to assist with interpretation, visualization, and obtaining accurate measurements of inaccessible areas. However, in stratigraphic mapping applications in complex terrain, it is difficult to acquire information with sufficient detail at a wide spatial coverage with conventional techniques. We demonstrate the potential of a UAV and Structure from Motion (SfM) photogrammetric approach for improving 3D stratigraphic mapping applications within a complex badland topography. Our case study is performed in Dinosaur Provincial Park (Alberta, Canada), mapping late Cretaceous fluvial meander belt deposits of the Dinosaur Park formation amidst a succession of steeply sloping hills and abundant drainages - creating a challenge for stratigraphic mapping. The UAV-SfM dataset (2 cm spatial resolution) is compared directly with a combined satellite and aerial LiDAR dataset (30 cm spatial resolution) to reveal advantages and limitations of each dataset before presenting a unique workflow that utilizes the dense point cloud from the UAV-SfM dataset for analysis. The UAV-SfM dense point cloud minimizes distortion, preserves 3D structure, and records an RGB attribute - adding potential value in future studies. The proposed UAV-SfM workflow allows for high spatial resolution remote sensing of stratigraphy in complex topographic environments. This extended capability can add value to field observations and has the potential to be integrated with subsurface petroleum models.

Performance Evaluations of Pump-and-Treat Remediations

EPA Pesticide Factsheets

Recent research has led to a better understanding of the complex chemical and physical processes controlling the movement of contaminants through the subsurface, and the ability to pump such contaminants...

Directional reflectance and milli-scale feather morphology of the African Emerald Cuckoo, Chrysococcyx cupreus.

PubMed

Harvey, Todd Alan; Bostwick, Kimberly S; Marschner, Steve

2013-09-06

Diverse plumages have evolved among birds through complex morphological modifications. We investigate how the interplay of light with surface and subsurface feather morphology determines the direction of light propagation, an understudied aspect of avian visual signalling. We hypothesize that milli-scale modifications of feathers produce anisotropic reflectance, the direction of which may be predicted by the orientation of the milli-scale structure. The subject of this study is the African Emerald Cuckoo, Chrysococcyx cupreus, noted for its shimmering green iridescent appearance. Using a spherical gantry, we measured the change in the directional reflectance across the feather surface and over a hemisphere of incident lighting directions. Using a microCT scanner, we also studied the morphology of the structural branches of the barb. We tracked the changes in the directional reflectance to the orientation of the structural branches as observed in the CT data. We conclude that (i) the far-field signal of the feather consists of multiple specular components, each associated with a different structural branch and (ii) the direction of each specular component is correlated to the orientation of the corresponding structure.

Directional reflectance and milli-scale feather morphology of the African Emerald Cuckoo, Chrysococcyx cupreus

PubMed Central

Harvey, Todd Alan; Bostwick, Kimberly S.; Marschner, Steve

2013-01-01

Diverse plumages have evolved among birds through complex morphological modifications. We investigate how the interplay of light with surface and subsurface feather morphology determines the direction of light propagation, an understudied aspect of avian visual signalling. We hypothesize that milli-scale modifications of feathers produce anisotropic reflectance, the direction of which may be predicted by the orientation of the milli-scale structure. The subject of this study is the African Emerald Cuckoo, Chrysococcyx cupreus, noted for its shimmering green iridescent appearance. Using a spherical gantry, we measured the change in the directional reflectance across the feather surface and over a hemisphere of incident lighting directions. Using a microCT scanner, we also studied the morphology of the structural branches of the barb. We tracked the changes in the directional reflectance to the orientation of the structural branches as observed in the CT data. We conclude that (i) the far-field signal of the feather consists of multiple specular components, each associated with a different structural branch and (ii) the direction of each specular component is correlated to the orientation of the corresponding structure. PMID:23825113

Robust Representation of Integrated Surface-subsurface Hydrology at Watershed Scales

NASA Astrophysics Data System (ADS)

Painter, S. L.; Tang, G.; Collier, N.; Jan, A.; Karra, S.

2015-12-01

A representation of integrated surface-subsurface hydrology is the central component to process-rich watershed models that are emerging as alternatives to traditional reduced complexity models. These physically based systems are important for assessing potential impacts of climate change and human activities on groundwater-dependent ecosystems and water supply and quality. Integrated surface-subsurface models typically couple three-dimensional solutions for variably saturated flow in the subsurface with the kinematic- or diffusion-wave equation for surface flows. The computational scheme for coupling the surface and subsurface systems is key to the robustness, computational performance, and ease-of-implementation of the integrated system. A new, robust approach for coupling the subsurface and surface systems is developed from the assumption that the vertical gradient in head is negligible at the surface. This tight-coupling assumption allows the surface flow system to be incorporated directly into the subsurface system; effects of surface flow and surface water accumulation are represented as modifications to the subsurface flow and accumulation terms but are not triggered until the subsurface pressure reaches a threshold value corresponding to the appearance of water on the surface. The new approach has been implemented in the highly parallel PFLOTRAN (www.pflotran.org) code. Several synthetic examples and three-dimensional examples from the Walker Branch Watershed in Oak Ridge TN demonstrate the utility and robustness of the new approach using unstructured computational meshes. Representation of solute transport in the new approach is also discussed. Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes.

How to Access and Sample the Deep Subsurface of Mars

NASA Technical Reports Server (NTRS)

Briggs, G.; Blacic, J.; Dreesen, D.; Mockler, T.

2000-01-01

We are developing a technology roadmap to support a series of Mars lander missions aimed at successively deeper and more comprehensive explorations of the Martian subsurface. The proposed mission sequence is outlined. Key to this approach is development of a drilling and sampling technology robust and flexible enough to successfully penetrate the presently unknown subsurface geology and structure. Martian environmental conditions, mission constraints of power and mass and a requirement for a high degree of automation all limit applicability of many proven terrestrial drilling technologies. Planetary protection and bioscience objectives further complicate selection of candidate systems. Nevertheless, recent advances in drilling technologies for the oil & gas, mining, underground utility and other specialty drilling industries convinces us that it will be possible to meet science and operational objectives of Mars subsurface exploration.

Extrapolating subsurface geometry by surface expressions in transpressional strike slip fault, deduced from analogue experiments with settings of rheology and convergence angle

NASA Astrophysics Data System (ADS)

Hsieh, Shang Yu; Neubauer, Franz

2015-04-01

The internal structure of major strike-slip faults is still poorly understood, particularly how to extrapolate subsurface structures by surface expressions. Series of brittle analogue experiments by Leever et al., 2011 resulted the convergence angle is the most influential factor for surface structures. Further analogue models with different ductile settings allow a better understanding in extrapolating surface structures to the subsurface geometry of strike-slip faults. Fifteen analogue experiments were constructed to represent strike-slip faults in nature in different geological settings. As key parameters investigated in this study include: (a) the angle of convergence, (b) the thickness of brittle layer, (c) the influence of a rheological weak layer within the crust, and (d) influence of a thick and rheologically weak layer at the base of the crust. The experiments are aimed to explain first order structures along major transcurrent strike-slip faults such as the Altyn, Kunlun, San Andrea and Greendale (Darfield earthquake 2010) faults. The preliminary results show that convergence angle significantly influences the overall geometry of the transpressional system with greater convergence angles resulting in wider fault zones and higher elevation. Different positions, densities and viscosities of weak rheological layers have not only different surface expressions but also affect the fault geometry in the subsurface. For instance, rheological weak material in the bottom layer results in stretching when experiment reaches a certain displacement and a buildup of a less segmented, wide positive flower structure. At the surface, a wide fault valley in the middle of the fault zone is the reflection of stretching along the velocity discontinuity at depth. In models with a thin and rheologically weaker layer in the middle of the brittle layer, deformation is distributed over more faults and the geometry of the fault zone below and above the weak zone shows significant differences, suggesting that the correlation of structures across a weak layer has to be supported by geophysical data, which help constraining the geometry of the deep part. This latter experiment has significantly similar phenomena in reality, such as few pressure ridges along Altyn fault. The experimental results underline the need to understand the role of the convergence angle and the influence of rheology on fault evolution, in order to connect between surface deformation and subsurface geometry.

A 3D object-based model to simulate highly-heterogeneous, coarse, braided river deposits

NASA Astrophysics Data System (ADS)

Huber, E.; Huggenberger, P.; Caers, J.

2016-12-01

There is a critical need in hydrogeological modeling for geologically more realistic representation of the subsurface. Indeed, widely-used representations of the subsurface heterogeneity based on smooth basis functions such as cokriging or the pilot-point approach fail at reproducing the connectivity of high permeable geological structures that control subsurface solute transport. To realistically model the connectivity of high permeable structures of coarse, braided river deposits, multiple-point statistics and object-based models are promising alternatives. We therefore propose a new object-based model that, according to a sedimentological model, mimics the dominant processes of floodplain dynamics. Contrarily to existing models, this object-based model possesses the following properties: (1) it is consistent with field observations (outcrops, ground-penetrating radar data, etc.), (2) it allows different sedimentological dynamics to be modeled that result in different subsurface heterogeneity patterns, (3) it is light in memory and computationally fast, and (4) it can be conditioned to geophysical data. In this model, the main sedimentological elements (scour fills with open-framework-bimodal gravel cross-beds, gravel sheet deposits, open-framework and sand lenses) and their internal structures are described by geometrical objects. Several spatial distributions are proposed that allow to simulate the horizontal position of the objects on the floodplain as well as the net rate of sediment deposition. The model is grid-independent and any vertical section can be computed algebraically. Furthermore, model realizations can serve as training images for multiple-point statistics. The significance of this model is shown by its impact on the subsurface flow distribution that strongly depends on the sedimentological dynamics modeled. The code will be provided as a free and open-source R-package.

Microbial community assembly patterns under incipient conditions in a basaltic soil system

NASA Astrophysics Data System (ADS)

Sengupta, A.; Stegen, J.; Alves Meira Neto, A.; Wang, Y.; Chorover, J.; Troch, P. A. A.; Maier, R. M.

2017-12-01

In sub-surface environments, the biotic components are critically linked to the abiotic processes. However, there is limited understanding of community establishment, functional associations, and community assembly processes of such microbes in sub-surface environments. This study presents the first analysis of microbial signatures in an incipient terrestrial basalt soil system conducted under controlled conditions. A sub-meter scale sampling of a soil mesocosm revealed the contrasting distribution patterns of simple soil parameters such as bulk density and electrical conductivity. Phylogenetic analysis of 16S rRNA gene indicated the presence of a total 40 bacterial and archaeal phyla, with high relative abundance of Actinobacteria on the surface and highest abundance of Proteobacteria throughout the system. Community diversity patterns were inferred to be dependent on depth profile and average water content in the system. Predicted functional gene analysis suggested mixotrophy lifestyles with both autotrophic and heterotrophic metabolisms, likelihood of a unique salt tolerant methanogenic pathway with links to novel Euryarchea, signatures of an incomplete nitrogen cycle, and predicted enzymes of extracellular iron (II) to iron (III) conversion followed by intracellular uptake, transport and regulation. Null modeling revealed microbial community assembly was predominantly governed by variable selection, but the influence of the variable selection did not show systematic spatial structure. The presence of significant heterogeneity in predicted functions and ecologically deterministic shifts in community composition in a homogeneous incipient basalt highlights the complexity exhibited by microorganisms even in the simplest of environmental systems. This presents an opportunity to further develop our understanding of how microbial communities establish, evolve, impact, and respond in sub-surface environments.

Hydro-environmental changes and their influence on the subsurface environment in the context of urban development.

PubMed

Yoshikoshi, Akihisa; Adachi, Itsu; Taniguchi, Tomomasa; Kagawa, Yuichi; Kato, Masahiro; Yamashita, Akio; Todokoro, Taiko; Taniguchi, Makoto

2009-04-15

The relationship between urban development and hydro-environmental change, particularly with regard to the subsurface environment is examined for three coastal cities affected by Asian monsoons (Tokyo and Osaka in Japan, and Bangkok in Thailand). Major differences in subsurface changes among these cities are closely related to city size, urban structure, and the timing, stage and extent of urbanization as well as the natural environment. The work shows that the urban development has not affected the Bangkok subsurface hydro-environment in the same way it has in Tokyo and Osaka. Three reasons for the difference account for this, (1) Bangkok's abundant annual rainfall, (2) Bangkok has the smallest ratio of impervious pavement surface area, meaning that surface water can more easily infiltrate underground., (3) the degree and extent of urbanization. Bangkok's subsurface hydro-environment has not been heavily affected because underground development has not yet reached deep subterranean areas. By researching yet more cities, at different stages of urbanization to that of Tokyo, Osaka and Bangkok, we plan to quantitatively examine urbanization and its influence on subsurface hydro-environments. This research will help limit damage to developing cities that are not yet experiencing subsurface failures but which are expected to confront these problems in the future.

Mechanical properties and molecular structure analysis of subsurface dentin after Er:YAG laser irradiation.

PubMed

He, Zhengdi; Chen, Lingling; Hu, Xuejuan; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Ruan, Shuangchen

2017-10-01

The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS). The dentin 5-50µm depth beneath the lased surface was determined as testing area. Two-way analysis of variance (ANOVA) were used to compare the mechanical values between lased and untreated subsurface dentin (P = 0.05). A laser affected subsurface dentin layer after Er:YAG laser treatment is present. The laser irradiation is considered to decrease the mechanical properties in the superficial subsurface layer (<15µm deep). There was no significant difference in nanohardness and Young's modulus between lased subsurface dentin and untreated dentin (p > 0.05) under the depth of 15µm. However, the dentin at 5µm and 10µm depth beneath the lased surface exhibited significantly lower (~ 47.8% and ~ 33.6% respectively) hardness (p < 0.05). Er:YAG laser irradiation affected both mineral and organic components in subsurface dentin layer, a higher degree of crystallinity and reduced organic compounds occurred in the lased subsurface dentin. Under the tested laser parameters, Er:YAG laser irradiation causes lower mechanical values and reduction of organic components in subsurface dentin, which has deleterious effects on resin adhesion to this area. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Sub-crop geologic map of pre-Tertiary rocks in the Yucca Flat and northern Frenchman Flat areas, Nevada Test Site, southern Nevada

USGS Publications Warehouse

Cole, James C.; Harris, Anita G.; Wahl, Ronald R.

1997-01-01

This map displays interpreted structural and stratigraphic relations among the Paleozoic and older rocks of the Nevada Test Site region beneath the Miocene volcanic rocks and younger alluvium in the Yucca Flat and northern Frenchman Flat basins. These interpretations are based on a comprehensive examination and review of data for more than 77 drillholes that penetrated part of the pre-Tertiary basement beneath these post-middle Miocene structural basins. Biostratigraphic data from conodont fossils were newly obtained for 31 of these holes, and a thorough review of all prior microfossil paleontologic data is incorporated in the analysis. Subsurface relationships are interpreted in light of a revised regional geologic framework synthesized from detailed geologic mapping in the ranges surrounding Yucca Flat, from comprehensive stratigraphic studies in the region, and from additional detailed field studies on and around the Nevada Test Site.All available data indicate the subsurface geology of Yucca Flat is considerably more complicated than previous interpretations have suggested. The western part of the basin, in particular, is underlain by relics of the eastward-vergent Belted Range thrust system that are folded back toward the west and thrust by local, west-vergent contractional structures of the CP thrust system. Field evidence from the ranges surrounding the north end of Yucca Flat indicate that two significant strike-slip faults track southward beneath the post-middle Miocene basin fill, but their subsurface traces cannot be closely defined from the available evidence. In contrast, the eastern part of the Yucca Flat basin is interpreted to be underlain by a fairly simple north-trending, broad syncline in the pre-Tertiary units. Far fewer data are available for the northern Frenchman Flat basin, but regional analysis indicates the pre- Tertiary structure there should also be relatively simple and not affected by thrusting.This new interpretation has implications for ground water flow through pre-Tertiary rocks beneath the Yucca Flat and northern Frenchman Flat areas, and has consequences for ground water modeling and model validation. Our data indicate that the Mississippian Chainman Shale is not a laterally extensive confining unit in the western part of the basin because it is folded back onto itself by the convergent structures of the Belted Range and CP thrust systems. Early and Middle Paleozoic limestone and dolomite are present beneath most of both basins and, regardless of structural complications, are interpreted to form a laterally continuous and extensive carbonate aquifer. Structural culmination that marks the French Peak accommodation zone along the topographic divide between the two basins provides a lateral pathway through highly fractured rock between the volcanic aquifers of Yucca Flat and the regional carbonate aquifer. This pathway may accelerate the migration of ground-water contaminants introduced by underground nuclear testing toward discharge areas beyond the Nevada Test Site boundaries. Predictive three-dimensional models of hydrostratigraphic units and ground-water flow in the pre-Tertiary rocks of subsurface Yucca Flat are likely to be unrealistic due to the extreme structural complexities. The interpretation of hydrologic and geochemical data obtained from monitoring wells will be difficult to extrapolate through the flow system until more is known about the continuity of hydrostratigraphic units.

Shallow subsurface structure estimated from dense aftershock records and microtremor observations in Furukawa district, Miyagi, Japan

NASA Astrophysics Data System (ADS)

Goto, Hiroyuki; Mitsunaga, Hitoshi; Inatani, Masayuki; Iiyama, Kahori; Hada, Koji; Ikeda, Takaaki; Takaya, Toshiyasu; Kimura, Sayaka; Akiyama, Ryohei; Sawada, Sumio; Morikawa, Hitoshi

2017-11-01

We conducted single-site and array observations of microtremors in order to revise the shallow subsurface structure of the Furukawa district, Miyagi, Japan, where severe residential damage was reported during the Great Eastern Japan Earthquake of 2011, off the Pacific coast of Tohoku. The phase velocities of Rayleigh waves are estimated from array observations at three sites, and S-wave velocity models are established. The spatial distribution of predominant periods is estimated for the surface layer, on the basis of the spectral ratio of horizontal and vertical components (H/V) of microtremors obtained from single-site observations. We then compared ground motion records from a dense seismometer network with results of microtremor observations, and revised a model of the shallow (~100 m) subsurface structure in the Furukawa district. The model implies that slower near-surface S-wave velocity and deeper basement are to be found in the southern and eastern areas. It was found that the damage in residential structures was concentrated in an area where the average value for the transfer functions in the frequency range of 2 to 4 Hz was large.

Contamination and restoration of groundwater aquifers.

PubMed Central

Piver, W T

1993-01-01

Humans are exposed to chemicals in contaminated groundwaters that are used as sources of drinking water. Chemicals contaminate groundwater resources as a result of waste disposal methods for toxic chemicals, overuse of agricultural chemicals, and leakage of chemicals into the subsurface from buried tanks used to hold fluid chemicals and fuels. In the process, both the solid portions of the subsurface and the groundwaters that flow through these porous structures have become contaminated. Restoring these aquifers and minimizing human exposure to the parent chemicals and their degradation products will require the identification of suitable biomarkers of human exposure; better understandings of how exposure can be related to disease outcome; better understandings of mechanisms of transport of pollutants in the heterogeneous structures of the subsurface; and field testing and evaluation of methods proposed to restore and cleanup contaminated aquifers. In this review, progress in these many different but related activities is presented. PMID:8354172

Geometry and slip rates of active blind thrusts in a reactivated back-arc rift using shallow seismic imaging: Toyama basin, central Japan

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Kato, Naoko; Sato, Hiroshi; Koshiya, Shin; Toda, Shigeru; Kobayashi, Kenta

2017-10-01

Active blind thrust faults, which can be a major seismic hazard in urbanized areas, are commonly difficult to image with seismic reflection surveys. To address these challenges in coastal plains, we collected about 8 km-long onshore high-resolution two-dimensional (2D) seismic reflection data using a dense array of 800 geophones across compressionally reactivated normal faults within a failed rift system located along the southwestern extension of the Toyama trough in the Sea of Japan. The processing of the seismic reflection data illuminated their detailed subsurface structures to depths of about 3 km. The interpreted depth-converted section, correlated with nearby Neogene stratigraphy, indicated the presence of and along-strike variation of previously unrecognized complex thrust-related structures composed of active fault-bend folds coupled with pairs of flexural slip faults within the forelimb and newly identified frontal active blind thrusts beneath the alluvial plain. In addition, growth strata and fold scarps that deform lower to upper Pleistocene units record the recent history of their structural growth and fault activity. This case shows that shallow seismic reflection imaging with densely spaced seismic recorders is a useful tool in defining locations, recent fault activity, and complex geometry of otherwise inaccessible active blind thrust faults.

The research on the buried public monumental complexes of Lupiae (Lecce) by geophysical prospecting

NASA Astrophysics Data System (ADS)

Leucci, Giovanni; De Giorgi, Lara; Di Giacomo, Giacomo; Ditaranto, Imma; Miccoli, Ilaria; Scardozzi, Giuseppe

2017-10-01

Ongoing and extensive urbanisation may threaten important archaeological structures that are still buried in urban areas. The ground penetrating radar (GPR) method is the most promising alternative for resolving buried archaeological structures in urban territories. This paper presents a case study that involves a geophysical survey employing the surface three-dimensional (3D) GPR techniques, in order to archaeologically characterise the investigated areas. The site is located in the south-western sector of the historical centre of Lecce (Apulia, Italy), where the modern city overlaps the main public monuments of the Roman municipium of Lupiae, only partially preserved or excavated: the amphitheatre, the theatre, the baths and maybe also the Forum. GPR measurements, integrated with the results of archaeological excavations and the topographical surveys of the preserved remains, were carried out in several areas regarding sectors of the ancient roman city. The GPR data were collected along a dense network of parallel profiles. The GPR sections were processed applying specific filters to the data in order to enhance their information content. The GPR images significantly contributed in reconstructing the complex subsurface properties in these modern urban areas. Strong GPR reflections features were correlated with possible ancient structures and they were integrated in the digital archaeological map of the city.

Studies of high coverage oxidation of the Cu(100) surface using low energy positrons

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Maddox, W. B.; Weiss, A. H.

2012-02-01

The study of oxidation of single crystal metal surfaces is important in understanding the corrosive and catalytic processes associated with thin film metal oxides. The structures formed on oxidized transition metal surfaces vary from simple adlayers of chemisorbed oxygen to more complex structures which result from the diffusion of oxygen into subsurface regions. In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. Calculations are performed for various high coverage missing row structures ranging between 0.50 and 1.50 ML oxygen coverage. The results of calculations of positron binding energy, positron work function, and annihilation characteristics of surface trapped positrons with relevant core electrons as function of oxygen coverage are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES).

Modular evaluation method for subsurface activities (MEMSA). A novel approach for integrating social acceptance in a permit decision-making process for subsurface activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Os, Herman W.A. van, E-mail: h.w.a.van.os@rug.nl; Herber, Rien, E-mail: rien.herber@rug.nl; Scholtens, Bert, E-mail: l.j.r.scholtens@rug.nl

We investigate how the decision support system ‘Modular Evaluation Method Subsurface Activities’ (MEMSA) can help facilitate an informed decision-making process for permit applications of subsurface activities. To this end, we analyze the extent the MEMSA approach allows for a dialogue between stakeholders in a transparent manner. We use the exploration permit for the underground gas storage facility at the Pieterburen salt dome (Netherlands) as a case study. The results suggest that the MEMSA approach is flexible enough to adjust to changing conditions. Furthermore, MEMSA provides a novel way for identifying structural problems and possible solutions in permit decision-making processes formore » subsurface activities, on the basis of the sensitivity analysis of intermediate rankings. We suggest that the planned size of an activity should already be specified in the exploration phase, because this would allow for a more efficient use of the subsurface as a whole. We conclude that the host community should be involved to a greater extent and in an early phase of the permit decision-making process, for example, already during the initial analysis of the project area of a subsurface activity. We suggest that strategic national policy goals are to be re-evaluated on a regular basis, in the form of a strategic vision for the subsurface, to account for timing discrepancies between the realization of activities and policy deadlines, because this discrepancy can have a large impact on the necessity and therefore acceptance of a subsurface activity.« less

Large-scale 3D inversion of marine controlled source electromagnetic data using the integral equation method

NASA Astrophysics Data System (ADS)

Zhdanov, M. S.; Cuma, M.; Black, N.; Wilson, G. A.

2009-12-01

The marine controlled source electromagnetic (MCSEM) method has become widely used in offshore oil and gas exploration. Interpretation of MCSEM data is still a very challenging problem, especially if one would like to take into account the realistic 3D structure of the subsurface. The inversion of MCSEM data is complicated by the fact that the EM response of a hydrocarbon-bearing reservoir is very weak in comparison with the background EM fields generated by an electric dipole transmitter in complex geoelectrical structures formed by a conductive sea-water layer and the terranes beneath it. In this paper, we present a review of the recent developments in the area of large-scale 3D EM forward modeling and inversion. Our approach is based on using a new integral form of Maxwell’s equations allowing for an inhomogeneous background conductivity, which results in a numerically effective integral representation for 3D EM field. This representation provides an efficient tool for the solution of 3D EM inverse problems. To obtain a robust inverse model of the conductivity distribution, we apply regularization based on a focusing stabilizing functional which allows for the recovery of models with both smooth and sharp geoelectrical boundaries. The method is implemented in a fully parallel computer code, which makes it possible to run large-scale 3D inversions on grids with millions of inversion cells. This new technique can be effectively used for active EM detection and monitoring of the subsurface targets.

Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability.

NASA Astrophysics Data System (ADS)

Frampton, Andrew

2017-04-01

There is a need for improved understanding of the mechanisms controlling subsurface solute transport in the active layer in order to better understand permafrost-hydrological-carbon feedbacks, in particular with regards to how dissolved carbon is transported in coupled surface and subsurface terrestrial arctic water systems under climate change. Studying solute transport in arctic systems is also relevant in the context of anthropogenic pollution which may increase due to increased activity in cold region environments. In this contribution subsurface solute transport subject to ground surface warming causing permafrost thaw and active layer change is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. These travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles. The impact these change mechanisms have on solute and dissolved substance transport is further analysed by integrating pathway analysis with a Lagrangian approach, incorporating considerations for both dissolved organic and inorganic carbon releases. Further model development challenges are also highlighted and discussed, including coupling between subsurface and surface runoff, soil deformations, as well as site applications and larger system scales.

Organic and Inorganic Carbon in the Rio Tinto (Spain) Deep Subsurface System: a Possible Model for Subsurface Carbon and Lithoautotrophs on Mars.

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.; Stoker, C. R.; MARTE Science Team

2007-12-01

The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of great relevance to astrobiology including the search for past/present life on Mars. Conditions on the Martian surface do not support biological activity but the subsurface might preserve organics and host subsurface life [1]. A key requirement for the analysis of subsurface samples on Mars is the ability to characterize organic vs. inorganic carbon pools. This information is needed to determine if the sample contains organic material of biological origin and/ or to establish if pools of inorganic carbon can support subsurface biospheres. The Mars Analog Rio Tinto Experiment (MARTE) performed deep drilling of cores i.e., down to 165-m depth, in a volcanically-hosted-massive-sulfide deposit at Rio Tinto, Spain, which is considered an important analog of the Sinus Meridiani site on Mars. Results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and anaerobic chemoautotrophs, and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions, which is an ideal model analog for a deep subsurface Martian environment. We report here on the distribution of organic (C-org: 0.01-0.3Wt% and inorganic carbon (IC = 0.01-7.0 Wt%) in a subsurface rock system including weathered/oxidized i.e., gossan, and unaltered pyrite stockwork. Cores were analyzed from 3 boreholes (BH-4, BH-7, and BH-8) that penetrated down to a depth of ~165 m into massive sulfide. Nearsurface phyllosilicate rich-pockets contain the highest amounts of organics (0.3Wt%) [2], while the deeper rocks contain the highest amount of carbonates. Assessing the amount of C pools available throughout the RT subsurface brings key insight on the type of trophic system sustaining its microbial ecosystem (i.e., heterotrophs vs. autotrophs) and the biogeochemical relationships that characterize a new type of subsurface biosphere at RT. This potentially novel biosphere on Earth could be used as a model to test for extant and extinct life on Mars. Furthermore, having found carbonates in an hyperacidic system (pH ~2.3) brings new insights on the possible occurrence of deep carbonates deposits under low-pH condition on Mars. [1] Boston, P.J., et al., 1992. Icarus 95,300-308; Bonaccorsi, Stoker and Sutter, 2007 Accepted with review in Astrobiology.

Fluid-Faulting Interactions Examined Though Massive Waveform-Based Analyses of Earthquake Swarms in Volcanic and Tectonic Settings: Mammoth Mountain, Long Valley, Lassen, and Fillmore, California Swarms, 2014-2015

NASA Astrophysics Data System (ADS)

Shelly, D. R.; Ellsworth, W. L.; Prejean, S. G.; Hill, D. P.; Hardebeck, J.; Hsieh, P. A.

2015-12-01

Earthquake swarms, sequences of sustained seismicity, convey active subsurface processes that sometimes precede larger tectonic or volcanic episodes. Their extended activity and spatiotemporal migration can often be attributed to fluid pressure transients as migrating crustal fluids (typically water and CO2) interact with subsurface structures. Although the swarms analyzed here are interpreted to be natural in origin, the mechanisms of seismic activation likely mirror those observed for earthquakes induced by industrial fluid injection. Here, we use massive-scale waveform correlation to detect and precisely locate 3-10 times as many earthquakes as included in routine catalogs for recent (2014-2015) swarms beneath Mammoth Mountain, Long Valley Caldera, Lassen Volcanic Center, and Fillmore areas of California, USA. These enhanced catalogs, with location precision as good as a few meters, reveal signatures of fluid-faulting interactions, such as systematic migration, fault-valve behavior, and fracture mesh structures, not resolved in routine catalogs. We extend this analysis to characterize source mechanism similarity even for very small newly detected events using relative P and S polarity estimates. This information complements precise locations to define fault complexities that would otherwise be invisible. In particular, although swarms often consist of groups of highly similar events, some swarms contain a population of outliers with different slip and/or fault orientations. These events highlight the complexity of fluid-faulting interactions. Despite their different settings, the four swarms analyzed here share many similarities, including pronounced hypocenter migration suggestive of a fluid pressure trigger. This includes the July 2015 Fillmore swarm, which, unlike the others, occurred outside of an obvious volcanic zone. Nevertheless, it exhibited systematic westward and downdip migration on a ~1x1.5 km low-angle, NW-dipping reverse fault at midcrustal depth.

Terrain and subsurface influences on runoff generation in a steep, deep, highly weathered system

NASA Astrophysics Data System (ADS)

Mallard, J. M.; McGlynn, B. L.; Richter, D. D., Jr.

2017-12-01

Our understanding of runoff generation in regions characterized by deep, highly weathered soils is incomplete, despite the prevalence occupation of these landscapes worldwide. To address this, we instrumented a first-order watershed in the Piedmont of South Carolina, USA, a region that extends east of the Appalachians from Maryland to Alabama, and home to some of the most rapid population growth in the country. Although regionally the relief is modest, the landscape is often highly dissected and local slopes can be steep and highly varied. The typical soils of the region are kaolinite dominated ultisols, with hydrologic properties controlled by argillic Bt horizons, often with >50% clay-size fraction. The humid subtropical climate creates relatively consistent precipitation intra-annually and seasonally variable energy availability. Consequently, the mixed deciduous and coniferous tree cover creates a strong evapotranspiration-mediated hydrologic dynamic. While moist soils and extended stream networks are typical from late fall through spring, relatively dry soils and contracting stream networks emerge in the summer and early fall. Here, we seek to elucidate the relative influence of the vertical soil and spatial terrain structure of this region on watershed hillslope hydrology and subsequent runoff generation. We installed a network of nested, shallow groundwater wells and soil water content probes within an ephemeral to first-order watershed to continuously measure soil and groundwater dynamics across soil horizons and landscape position. We also recorded local precipitation and discharge from this watershed. Most landscape positions exhibited minimal water table response to precipitation throughout dry summer periods, with infrequently observed responses rarely coincident with streamflow generation. In contrast, during the wetter late fall through early spring period, streamflow was driven by the interaction between transient perched water tables and topographically mediated redistribution of shallow groundwater downslope. Our findings suggest that understanding streamflow generation in regions possessing both complex terrain and complex vertical soil structure requires synchronous characterization of terrain mediated water redistribution and subsurface soil hydrology.

Seismic Reflection Imaging of the Tucson Basin and Subsurface Relations Between the Catalina Detachment System and the Santa Rita Fault, SE Arizona

NASA Astrophysics Data System (ADS)

Wagner, F. T.; Johnson, R. A.

2003-12-01

Industry seismic reflection data collected in SE Arizona in the 1970's imaged the structure of the Tucson basin, the low-angle Catalina detachment fault, and the Santa Rita fault. Recent reprocessing of these data, including detailed near-surface statics compensation and modern event-migration techniques, have served to better focus the subsurface images. The Tucson basin occupies an area of approximately 2600 km2 and is bounded to the northeast by the Catalina-Rincon metamorphic core complex and to the south by the Santa Rita Mountains. The basin is characterized by an apparent half-graben structure down dropped along the eastern side and filled with up to 3700 m of Oligocene to recent volcanic and sedimentary rocks. In the northern portion of the basin, the gently-dipping ( ˜30 degrees) Catalina detachment fault is imaged from the western flank of the core complex dipping to the southwest beneath the Tucson basin. The detachment surface is evident to several seconds two-way-time in the seismic data and is characterized by broad corrugations parallel to extension with wavelengths of tens of kilometers. In the southern portion of the basin, the Santa Rita fault is imaged at the northwest side of the Santa Rita Mountains and dips ˜20 degrees to the northwest beneath the Tucson basin. Large, rotated hanging-wall blocks are also imaged above both the Catalina detachment and Santa Rita faults. While the Catalina detachment fault is no longer active, geomorphic analysis of fault scarps along the western flank of the Santa Rita Mountains supports recent (60-100 ka) movement on the Santa Rita fault. Preliminary results indicate that the Santa Rita fault terminates against the Catalina detachment fault beneath the central basin, suggesting that the recent movement observed on this fault may be, in part, a reactivation of the older fault surface.

Subsurface earthworm casts can be important soil microsites specifically influencing the growth of grassland plants.

PubMed

Zaller, Johann G; Wechselberger, Katharina F; Gorfer, Markus; Hann, Patrick; Frank, Thomas; Wanek, Wolfgang; Drapela, Thomas

Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four Glomus taxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers- Aporrectodea caliginosa vs. vertical burrowers- Lumbricus terrestris ) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg -1 soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants.

Image-based overlay measurement using subsurface ultrasonic resonance force microscopy

NASA Astrophysics Data System (ADS)

Tamer, M. S.; van der Lans, M. J.; Sadeghian, H.

2018-03-01

Image Based Overlay (IBO) measurement is one of the most common techniques used in Integrated Circuit (IC) manufacturing to extract the overlay error values. The overlay error is measured using dedicated overlay targets which are optimized to increase the accuracy and the resolution, but these features are much larger than the IC feature size. IBO measurements are realized on the dedicated targets instead of product features, because the current overlay metrology solutions, mainly based on optics, cannot provide sufficient resolution on product features. However, considering the fact that the overlay error tolerance is approaching 2 nm, the overlay error measurement on product features becomes a need for the industry. For sub-nanometer resolution metrology, Scanning Probe Microscopy (SPM) is widely used, though at the cost of very low throughput. The semiconductor industry is interested in non-destructive imaging of buried structures under one or more layers for the application of overlay and wafer alignment, specifically through optically opaque media. Recently an SPM technique has been developed for imaging subsurface features which can be potentially considered as a solution for overlay metrology. In this paper we present the use of Subsurface Ultrasonic Resonance Force Microscopy (SSURFM) used for IBO measurement. We used SSURFM for imaging the most commonly used overlay targets on a silicon substrate and photoresist. As a proof of concept we have imaged surface and subsurface structures simultaneously. The surface and subsurface features of the overlay targets are fabricated with programmed overlay errors of +/-40 nm, +/-20 nm, and 0 nm. The top layer thickness changes between 30 nm and 80 nm. Using SSURFM the surface and subsurface features were successfully imaged and the overlay errors were extracted, via a rudimentary image processing algorithm. The measurement results are in agreement with the nominal values of the programmed overlay errors.

Imaging lateral groundwater flow in the shallow subsurface using stochastic temperature fields

NASA Astrophysics Data System (ADS)

Fairley, Jerry P.; Nicholson, Kirsten N.

2006-04-01

Although temperature has often been used as an indication of vertical groundwater movement, its usefulness for identifying horizontal fluid flow has been limited by the difficulty of obtaining sufficient data to draw defensible conclusions. Here we use stochastic simulation to develop a high-resolution image of fluid temperatures in the shallow subsurface at Borax Lake, Oregon. The temperature field inferred from the geostatistical simulations clearly shows geothermal fluids discharging from a group of fault-controlled hydrothermal springs, moving laterally through the subsurface, and mixing with shallow subsurface flow originating from nearby Borax Lake. This interpretation of the data is supported by independent geochemical and isotopic evidence, which show a simple mixing trend between Borax Lake water and discharge from the thermal springs. It is generally agreed that stochastic simulation can be a useful tool for extracting information from complex and/or noisy data and, although not appropriate in all situations, geostatistical analysis may provide good definition of flow paths in the shallow subsurface. Although stochastic imaging techniques are well known in problems involving transport of species, e.g. delineation of contaminant plumes from soil gas survey data, we are unaware of previous applications to the transport of thermal energy for the purpose of inferring shallow groundwater flow.

Using Vertical Electrical Soundings for Characterizing Hydrogeological and Tectonic Settings in Deir El-Adas Area, Yarmouk Basin, Syria

NASA Astrophysics Data System (ADS)

Al-Fares, Walid

2016-06-01

The present study is aimed at characterizing the subsurface geological and tectonic structure in Deir El-Adas area, by using Vertical Electrical Sounding survey (VES) and hydrogeological investigations, in order to determine the causes of the failure for the majority of the wells drilled in the area. The survey data was treated in three different approaches including direct VES inversion, pseudo-2D method and horizontal profiling, in order to maximize the reliability of the data interpretation. The results revealed the presence of a local faulted anticline structure at the top of the Paleogene formation, underneath the basaltic outcrops where Deir El-Adas village is situated. The appearance of this subsurface anticline structure has complicated the local hydro-geological situation, and most likely led to limitation of the groundwater recharge in the area. Moreover, the performed piezometric and discharge maps indicated the presence of a notable groundwater watershed, in addition to feeble water productivity of the wells drilled adjacent to Deir El-Adas, mostly related to the subsurface geological and tectonic settings in the area.

Subsurface site conditions and geology in the San Fernando earthquake area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duke, C.M.; Johnson, J.A.; Kharraz, Y.

1971-12-01

The report presents the progress to date in establishing the facts about dynamic subsurface properties and geological features in the area affected by the San Fernando earthquake of February 9, 1971. Special emphasis is given to the locations of accelerographs, seismoscopes and Seismological Field Survey aftershock instruments. Thirty shallow geophysical surveys were made for determination of S and P velocities, with damping measured at some sites. Deep velocity data were obtained from geophysical surveys by others. Soil Mechanics and water well borings by others were utilized. Published and ongoing geological studies were applied. Results are presented in the form ofmore » five geological cross-sections, nine subsurface exploration models extending through basement complex to depths of 14,000 feet, a general geologic map, the shallow geophysical surveys, and selected data on damping.« less

Characterization of steel rebar spacing using synthetic aperture radar imaging

NASA Astrophysics Data System (ADS)

Hu, Jie; Tang, Qixiang; Twumasi, Jones Owusu; Yu, Tzuyang

2018-03-01

Steel rebars is a vital component in reinforced concrete (RC) and prestressed concrete structures since they provide mechanical functions to those structures. Damages occurred to steel rebars can lead to the premature failure of concrete structures. Characterization of steel rebars using nondestructive evaluation (NDE) offers engineers and decision makers important information for effective/good repair of aging concrete structures. Among existing NDE techniques, microwave/radar NDE has been proven to be a promising technique for surface and subsurface sensing of concrete structures. The objective of this paper is to use microwave/radar NDE to characterize steel rebar grids in free space, as a basis for the subsurface sensing of steel rebars inside RC structures. A portable 10-GHz radar system based on synthetic aperture radar (SAR) imaging was used in this paper. Effect of rebar grid spacing was considered and used to define subsurface steel rebar grids. Five rebar grid spacings were used; 12.7 cm (5 in.), 17.78 cm (7 in.), 22.86 cm (9 in.), 27.94 cm (11 in.), and 33.02 cm (13 in.) # 3 rebars were used in all grid specimens. All SAR images were collected inside an anechoic chamber. It was found that SAR images can successfully capture the change of rebar grid spacing and used for quantifying the spacing of rebar grids. Empirical models were proposed to estimate actual rebar spacing and contour area using SAR images.

Subsurface Investigation of the Neogene Mygdonian Basin, Greece Using Magnetic Data

NASA Astrophysics Data System (ADS)

Ibraheem, Ismael M.; Gurk, Marcus; Tougiannidis, Nikolaos; Tezkan, Bülent

2018-02-01

A high-resolution ground and marine magnetic survey was executed to determine the structure of the subsurface and the thickness of the sedimentary cover in the Mygdonian Basin. A spacing of approximately 250 m or 500 m between measurement stations was selected to cover an area of 15 km × 22 km. Edge detectors such as total horizontal derivative (THDR), analytic signal (AS), tilt derivative (TDR), enhanced total horizontal gradient of tilt derivative (ETHDR) were applied to map the subsurface structure. Depth was estimated by power spectrum analysis, tilt derivative, source parameter imaging (SPI), and 2D-forward modeling techniques. Spectral analysis and SPI suggest a depth to the basement ranging from near surface to 600 m. For some selected locations, depth was also calculated using the TDR technique suggesting depths from 160 to 400 m. 2D forward magnetic modeling using existing boreholes as constraints was carried out along four selected profiles and confirmed the presence of alternative horsts and grabens formed by parallel normal faults. The dominant structural trends inferred from THDR, AS, TDR, and ETHDR are N-S, NW-SE, NE-SW and E-W. This corresponds with the known structural trends in the area. Finally, a detailed structural map showing the magnetic blocks and the structural architecture of the Mygdonian Basin was drawn up by collating all of the results.

Estimating the Subsurface Basement Topography of Dodge County, Wisconsin Using Three Dimensional Modeling of Gravity and Aeromagnetic Data

NASA Astrophysics Data System (ADS)

MacAlister, E.; Skalbeck, J.; Stewart, E.

2016-12-01

Since the late 1800's, geologic studies have been completed in Wisconsin in pursuit of understanding the basement topography and locating economically viable mineral resources. The doubly plunging Baraboo Syncline located in Columbia and Sauk Counties provides a classic record of Precambrian deformation. A similar buried structure is thought to exist in adjacent Dodge County based on a prominent aeromagnetic anomaly. For this study, 3-D modeling of gravity and aeromagnetic survey data was used to approximate the structure of the Precambrian basement topography beneath Dodge County, Wisconsin. The aim of the research was to determine a suitable basement topography grid using potential field data and then use this grid as the base for groundwater flow models. Geosoft Oasis Montaj GM-SYS 3D modeling software was used to build grids of subsurface layers and the model was constrained by well records of basement rock elevations located throughout the county. The study demonstrated that there is a complex network of crystalline basement structures that have been folded through tectonic activity during the Precambrian. A thick layer of iron rich sedimentary material was deposited on top of the basement rocks, causing a distinct magnetic signature that outlined the basement structure in the magnetic survey. Preliminary results reveal an iron layer with a density of 3.7 g/cm3 and magnetic susceptibility of 8000 x 10-6 cgs that is approximately 500 feet thick and ranges between elevations of -300 meters below and 400 meters above sea level. The 3-D model depths are consistent with depths from recent core drilling operations performed by the Wisconsin Geological and Natural History Survey. Knowing the depth to and structure of basement rock throughout Dodge County and Wisconsin plays an important role in understanding the geologic history of the region. Also, better resolution of the basement topography can enhance the accuracy of future groundwater flow models.

Quantifying structural uncertainty on fault networks using a marked point process within a Bayesian framework

NASA Astrophysics Data System (ADS)

Aydin, Orhun; Caers, Jef Karel

2017-08-01

Faults are one of the building-blocks for subsurface modeling studies. Incomplete observations of subsurface fault networks lead to uncertainty pertaining to location, geometry and existence of faults. In practice, gaps in incomplete fault network observations are filled based on tectonic knowledge and interpreter's intuition pertaining to fault relationships. Modeling fault network uncertainty with realistic models that represent tectonic knowledge is still a challenge. Although methods that address specific sources of fault network uncertainty and complexities of fault modeling exists, a unifying framework is still lacking. In this paper, we propose a rigorous approach to quantify fault network uncertainty. Fault pattern and intensity information are expressed by means of a marked point process, marked Strauss point process. Fault network information is constrained to fault surface observations (complete or partial) within a Bayesian framework. A structural prior model is defined to quantitatively express fault patterns, geometries and relationships within the Bayesian framework. Structural relationships between faults, in particular fault abutting relations, are represented with a level-set based approach. A Markov Chain Monte Carlo sampler is used to sample posterior fault network realizations that reflect tectonic knowledge and honor fault observations. We apply the methodology to a field study from Nankai Trough & Kumano Basin. The target for uncertainty quantification is a deep site with attenuated seismic data with only partially visible faults and many faults missing from the survey or interpretation. A structural prior model is built from shallow analog sites that are believed to have undergone similar tectonics compared to the site of study. Fault network uncertainty for the field is quantified with fault network realizations that are conditioned to structural rules, tectonic information and partially observed fault surfaces. We show the proposed methodology generates realistic fault network models conditioned to data and a conceptual model of the underlying tectonics.

Composition and structure of the shallow subsurface of Ceres revealed by crater morphology

NASA Astrophysics Data System (ADS)

Bland, Michael T.; Raymond, Carol A.; Schenk, Paul M.; Fu, Roger R.; Kneissl, Thomas; Pasckert, Jan Hendrik; Hiesinger, Harry; Preusker, Frank; Park, Ryan S.; Marchi, Simone; King, Scott D.; Castillo-Rogez, Julie C.; Russell, Christopher T.

2016-07-01

Before NASA’s Dawn mission, the dwarf planet Ceres was widely believed to contain a substantial ice-rich layer below its rocky surface. The existence of such a layer has significant implications for Ceres’s formation, evolution, and astrobiological potential. Ceres is warmer than icy worlds in the outer Solar System and, if its shallow subsurface is ice-rich, large impact craters are expected to be erased by viscous flow on short geologic timescales. Here we use digital terrain models derived from Dawn Framing Camera images to show that most of Ceres’s largest craters are several kilometres deep, and are therefore inconsistent with the existence of an ice-rich subsurface. We further show from numerical simulations that the absence of viscous relaxation over billion-year timescales implies a subsurface viscosity that is at least one thousand times greater than that of pure water ice. We conclude that Ceres’s shallow subsurface is no more than 30% to 40% ice by volume, with a mixture of rock, salts and/or clathrates accounting for the other 60% to 70%. However, several anomalously shallow craters are consistent with limited viscous relaxation and may indicate spatial variations in subsurface ice content.

Composition and structure of the shallow subsurface of Ceres revealed by crater morphology

USGS Publications Warehouse

Bland, Michael T.; Carol A. Raymond,; Schenk, Paul M.; Roger R. Fu,; Thomas Kneisl,; Hendrick Pasckert, Jan; Hiesinger, Harald; Frank Preusker,; Ryan S. Park,; Simone Marchi,; Scott King,; Castillo-Rogez, Julie C.; Christopher T. Russell,

2016-01-01

Before NASA’s Dawn mission, the dwarf planet Ceres was widely believed to contain a substantial ice-rich layer below its rocky surface. The existence of such a layer has significant implications for Ceres’s formation, evolution, and astrobiological potential. Ceres is warmer than icy worlds in the outer Solar System and, if its shallow subsurface is ice-rich, large impact craters are expected to be erased by viscous flow on short geologic timescales. Here we use digital terrain models derived from Dawn Framing Camera images to show that most of Ceres’s largest craters are several kilometres deep, and are therefore inconsistent with the existence of an ice-rich subsurface. We further show from numerical simulations that the absence of viscous relaxation over billion-year timescales implies a subsurface viscosity that is at least one thousand times greater than that of pure water ice. We conclude that Ceres’s shallow subsurface is no more than 30% to 40% ice by volume, with a mixture of rock, salts and/or clathrates accounting for the other 60% to 70%. However, several anomalously shallow craters are consistent with limited viscous relaxation and may indicate spatial variations in subsurface ice content.

Autonomous microexplosives subsurface tracing system final report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew

The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping ofmore » subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.« less

Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

NASA Astrophysics Data System (ADS)

Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

2017-12-01

Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined with additional geological information, modeling of the gravity signal based on the vertical component of the gravitational attraction was particularly useful to estimate the seasonal recharge leading to temporary groundwater storage in the vadose zone.

Radioactive waste management complex low-level waste radiological composite analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarthy, J.M.; Becker, B.H.; Magnuson, S.O.

1998-05-01

The composite analysis estimates the projected cumulative impacts to future members of the public from the disposal of low-level radioactive waste (LLW) at the Idaho National Engineering and Environmental Laboratory (INEEL) Radioactive Waste Management Complex (RWMC) and all other sources of radioactive contamination at the INEEL that could interact with the LLW disposal facility to affect the radiological dose. Based upon the composite analysis evaluation, waste buried in the Subsurface Disposal Area (SDA) at the RWMC is the only source at the INEEL that will significantly interact with the LLW facility. The source term used in the composite analysis consistsmore » of all historical SDA subsurface disposals of radionuclides as well as the authorized LLW subsurface disposal inventory and projected LLW subsurface disposal inventory. Exposure scenarios evaluated in the composite analysis include all the all-pathways and groundwater protection scenarios. The projected dose of 58 mrem/yr exceeds the composite analysis guidance dose constraint of 30 mrem/yr; therefore, an options analysis was conducted to determine the feasibility of reducing the projected annual dose. Three options for creating such a reduction were considered: (1) lowering infiltration of precipitation through the waste by providing a better cover, (2) maintaining control over the RWMC and portions of the INEEL indefinitely, and (3) extending the period of institutional control beyond the 100 years assumed in the composite analysis. Of the three options investigated, maintaining control over the RWMC and a small part of the present INEEL appears to be feasible and cost effective.« less

Fluid circulation and structural system of Cerritos Colorados geothermal field in La Primavera volcanic caldera (Mexico) inferred from geophysical surveys

NASA Astrophysics Data System (ADS)

Bolós, X.; Cifuentes-Nava, G.; Macias, J. L.; Sosa-Ceballos, G.; García-Tenorio, F.; Albor, M., III; Juarez, M.; Gamez, V.

2017-12-01

Hydrothermal activity in volcanic calderas is the consequence of energy transfer between deep magmatic chambers and subsurface layers saturated in water. This hydrothermal system is generated by convection of the groundwater supplied by meteoric water recharged and the ascent of hot volcanic gasses exsolved from deep magma reservoirs. Calderas are heterogeneous geological structures that due to their formation and evolution produced a complex stratigraphy. All of these heterogeneities can be affected by deformation and also by the presence of fractures and faults which constitute the main pathways whereby hydrothermal fluids can move easily through the surface as spring discharges and fumarolic activity. Geophysical methods have been used in the last decades to investigate the relationship between structural geology and hydrothermal systems in different volcanic areas around the world. In this work, we have focused on the role of subsurface structures to understand and localize the pathways of fluids related to the hydrothermal system of the Cerritos Colorados geothermal field. We focused in the central area of the caldera (P12 well and Cerritos Colorados graben), where active hydrothermal activity is evidenced by fumaroles, thermal anomalies, CO2 diffuse emission, and sulfur precipitation. We have applied a self-potential method (SP) that combined with temperature measurements that allowed to identify the main infiltration and ascending fluid zones in the area, and their specific surface temperature coinciding with fumarolic activity. From this data we an applied Electrical Resistivity Tomography (ERT) survey in two selected places. One ERT profile (1.2 km in length) was located in the P12 well area. A 3D resistivity model used with the equatorial method was carried out on the Cerritos Colorados graben area. Combining the results of the SP, TºC, and ERT data with a detailed structural map we identified the main degassing zones (i.e. fumaroles) that correspond to higher permeability zones located along normal and strike-slip faults. In conclusion, a strong structural control of the surface manifestation of these hydrothermal systems is deduced from our new data. Then, our results emphasize the importance of old structural boundaries that are controlled by intra-caldera tectonic structures.

The Lusi eruption site: insights from surface and subsurface investigations

NASA Astrophysics Data System (ADS)

Mazzini, A.

2017-12-01

The Indonesian Lusi eruption has been spewing boiling water, gas, and sediments since the 29th of May 2006. Initially, numerous aligned eruptions sites appeared along the Watukosek fault system (WFS) that was reactivated after the Yogyakarta earthquake occurring the 27th of May in the Java Island. Within weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. To date Lusi is still active and an area of 7 km2is covered by mud. Since its birth Lusi erupted with a pulsating behaviour. In the framework of the ERC grant "Lusi Lab" we conducted several years of monitoring and regional investigations coupling surface sampling and subsurface imaging in the region around Lusi. Ambient noise tomography studies, obtained with a local network of 31 stations, revealed for the first time subsurface images of the Lusi region and the adjacent Arjuno-Welirang (AW) volcanic complex. Results show that below the AW volcanic complex are present 5km deep magma chambers that are connected, through a defined corridor, with the roots of the Lusi eruption site. The Lusi subsurface shows the presence of a defined vertical hydrothermal plume that extends to at least 5km. Chemical analyses of the seeping fluids sampled from 1) the Lusi plume (using a specifically designed drone), 2) the region around Lusi, and 3) the fumaroles and the hydro thermal springs of AW, revealed striking similarities. More specifically a mantellic signature of the Lusi fluids confirms the scenario that Lusi represents a magmatic-driven hydrothermal system hosted in sedimentary basin. Seismic profiles interpretation, surface mapping, and fluid sampling show that the WFS, connecting AW and extending towards the NE of Java, acted as a preferential pathway for the igneous intrusion and fluids migration towards the subsurface. Petrography and dating of the clasts erupted at Lusi record high temperatures and indicate that the roots of the active conduit extend to at least 5km at depth, matching the observations and images obtained with geophysical investigations. Converging results support a scenario where igneous intrusions and hydrothermal fluid migrating from the AW complex moved towards the NE of Java. The triggered metamorphic reaction resulted in high overpressures that initiated the Lusi eruption site.

3D modeling of a dolerite intrusion from the photogrammetric and geophysical data integration.

NASA Astrophysics Data System (ADS)

Duarte, João; Machadinho, Ana; Figueiredo, Fernando; Mira, Maria

2015-04-01

The aims of this study is create a methodology based on the integration of data obtained from various available technologies, which allow a credible and complete evaluation of rock masses. In this particular case of a dolerite intrusion, which deployed an exploration of aggregates and belongs to the Jobasaltos - Extracção e Britagem. S.A.. Dolerite intrusion is situated in the volcanic complex of Serra de Todo-o-Mundo, Casais Gaiola, intruded in Jurassic sandstones. The integration of the surface and subsurface mapping, obtained by technology UAVs (Drone) and geophysical surveys (Electromagnetic Method - TEM 48 FAST), allows the construction of 2D and 3D models of the study local. The combination of the 3D point clouds produced from two distinct processes, modeling of photogrammetric and geophysical data, will be the basis for the construction of a single model of set. The rock masses in an integral perspective being visible their development above the surface and subsurface. The presentation of 2D and 3D models will give a perspective of structures, fracturation, lithology and their spatial correlations contributing to a better local knowledge, as well as its potential for the intended purpose. From these local models it will be possible to characterize and quantify the geological structures. These models will have its importance as a tool to assist in the analysis and drafting of regional models. The qualitative improvement in geological/structural modeling, seeks to reduce the value of characterization/cost ratio, in phase of prospecting, improving the investment/benefit ratio. This methodology helps to assess more accurately the economic viability of the projects.

Thin-skinned tectonics of the Upper Ojai Valley and Sulphur Mountain area, Ventura basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huftile, G.J.

1991-08-01

By integrating surface mapping with subsurface well data and drawing cross sections and subsurface maps, the geometry of shallow structures and their geologic history of the Upper Ojai Valley of California can be reconstructed. The geometry of shallow structures, the geologic history, and the location of earthquake foci then offer constraints on the deep structure of this complex area. The Upper Ojai Valley is a tectonic depression between opposing reverse faults. Its northern border is formed by the active, north-dipping San Cayetano fault, which has 6.0 km of stratigraphic separation in the Silverthread area of the Ojai oil field andmore » 2.6 km of stratigraphic separation west of Sisar Creek. The fault dies out farther west in Ojai Valley, where the south-vergent shortening is transferred to a blind thrust. The southern border of the Upper Ojai Valley is formed by the Quaternary Lion fault set, which dips south and merges into the Sisar decollement within the south-dipping, ductile, lower Miocene Rincon formation. By the middle Pleistocene, the Sulphur Mountain anticlinorium and the Big Canyon syncline began forming as a fault-propagation fold; the fault-propagation fold is rooted in the Sisar decollement, a passive backthrust rising from a blind thrust at depth. The formation of the Sulphur Mountain anticlinorium was followed closely by the ramping of the south-dipping Lion fault set to the surface over the nonmarine upper Pleistocene Saugus Formation. To the east, the San Cayetano fault overrides and folds the Lion Fault set near the surface. Area-balancing of the deformation shows shortening of 15.5 km, and suggests a 17 km depth to the brittle-ductile transition.« less

Papua New Guinea MT: Looking where seismic is blind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoversten, G.M.

1996-11-01

Hydrocarbon exploration in the Papuan fold belt is made extremely difficult by mountainous terrain, equatorial jungle and thick karstified Miocene limestones at the surface. The high-velocity karstified limestones at or near the surface often render the seismic technique useless for imaging the subsurface. In such areas magnetotellurics (MT) provides a valuable capability for mapping subsurface structure. Numerical and field data examples are presented which demonstrate the severity of the 1D errors and the improvements in accuracy which can be achieved using a 2D inverse solution. Two MT lines over adjacent anticlines, both with well control and seismic data, are usedmore » to demonstrate the application of 1D and 2D inversions for structural models. The example over the Hides anticline illustrates a situation where 1D inversion of either TE or TM mode provides essentially the same depth to base of Darai as 2D inversion of both TE and TM. The example over the Angore anticline illustrates the inadequacy of 1D inversion in structurally complex geology complicated by electrical statics. Four MT lines along the Angore anticline have been interpreted using 2D inversion. Three-dimensional modelling has been used to simulate 3D statics in an otherwise 2D earth. These data were used to test the Groom-Bailey (GB) decomposition for possible benefits in reducing static effects and estimating geoelectric strike in the Papua New Guinea (PNG) field data. It has been found that the GB decomposition can provide improved regional 2D strike estimates in 3D contaminated data. However, in situations such as PNG, where the regional 2D strike is well established and hence can be fixed, the GB decomposition provides apparent resistivities identical to those simply rotated to strike.« less

Three-dimensional hydrogeologic framework model of the Rio Grande transboundary region of New Mexico and Texas, USA, and northern Chihuahua, Mexico

USGS Publications Warehouse

Sweetkind, Donald S.

2017-09-08

As part of a U.S. Geological Survey study in cooperation with the Bureau of Reclamation, a digital three-dimensional hydrogeologic framework model was constructed for the Rio Grande transboundary region of New Mexico and Texas, USA, and northern Chihuahua, Mexico. This model was constructed to define the aquifer system geometry and subsurface lithologic characteristics and distribution for use in a regional numerical hydrologic model. The model includes five hydrostratigraphic units: river channel alluvium, three informal subdivisions of Santa Fe Group basin fill, and an undivided pre-Santa Fe Group bedrock unit. Model input data were compiled from published cross sections, well data, structure contour maps, selected geophysical data, and contiguous compilations of surficial geology and structural features in the study area. These data were used to construct faulted surfaces that represent the upper and lower subsurface hydrostratigraphic unit boundaries. The digital three-dimensional hydrogeologic framework model is constructed through combining faults, the elevation of the tops of each hydrostratigraphic unit, and boundary lines depicting the subsurface extent of each hydrostratigraphic unit. The framework also compiles a digital representation of the distribution of sedimentary facies within each hydrostratigraphic unit. The digital three-dimensional hydrogeologic model reproduces with reasonable accuracy the previously published subsurface hydrogeologic conceptualization of the aquifer system and represents the large-scale geometry of the subsurface aquifers. The model is at a scale and resolution appropriate for use as the foundation for a numerical hydrologic model of the study area.

Integration of airborne optical and thermal imagery for archaeological subsurface structures detection: the Arpi case study (Italy)

NASA Astrophysics Data System (ADS)

Bassani, C.; Cavalli, R. M.; Fasulli, L.; Palombo, A.; Pascucci, S.; Santini, F.; Pignatti, S.

2009-04-01

The application of Remote Sensing data for detecting subsurface structures is becoming a remarkable tool for the archaeological observations to be combined with the near surface geophysics [1, 2]. As matter of fact, different satellite and airborne sensors have been used for archaeological applications, such as the identification of spectral anomalies (i.e. marks) related to the buried remnants within archaeological sites, and the management and protection of archaeological sites [3, 5]. The dominant factors that affect the spectral detectability of marks related to manmade archaeological structures are: (1) the spectral contrast between the target and background materials, (2) the proportion of the target on the surface (relative to the background), (3) the imaging system characteristics being used (i.e. bands, instrument noise and pixel size), and (4) the conditions under which the surface is being imaged (i.e. illumination and atmospheric conditions) [4]. In this context, just few airborne hyperspectral sensors were applied for cultural heritage studies, among them the AVIRIS (Airborne Visible/Infrared Imaging Spectrometer), the CASI (Compact Airborne Spectrographic Imager), the HyMAP (Hyperspectral MAPping) and the MIVIS (Multispectral Infrared and Visible Imaging Spectrometer). Therefore, the application of high spatial/spectral resolution imagery arise the question on which is the trade off between high spectral and spatial resolution imagery for archaeological applications and which spectral region is optimal for the detection of subsurface structures. This paper points out the most suitable spectral information useful to evaluate the image capability in terms of spectral anomaly detection of subsurface archaeological structures in different land cover contexts. In this study, we assess the capability of MIVIS and CASI reflectances and of ATM and MIVIS emissivities (Table 1) for subsurface archaeological prospection in different sites of the Arpi archaeological area (southern Italy). We identify, for the selected sites, three main land cover overlying the buried structures: (a) photosynthetic (i.e. green low vegetation), (b) non-photosynthetic vegetation (i.e. yellow, dry low vegetation), and (c) dry bare soil. Afterwards, we analyse the spectral regions showing an inherent potential for the archaeological detection as a function of the land cover characteristics. The classified land cover units have been used in a spectral mixture analysis to assess the land cover fractional abundance surfacing the buried structures (i.e. mark-background system). The classification and unmixing results for the CASI, MIVIS and ATM remote sensing data processing showed a good accordance both in the land cover units and in the subsurface structures identification. The integrated analysis of the unmixing results for the three sensors allowed us to establish that for the land cover characterized by green and dry vegetation (occurrence higher than 75%), the visible and near infrared (VNIR) spectral regions better enhance the buried man-made structures. In particular, if the structures are covered by more than 75% of vegetation the two most promising wavelengths for their detection are the chlorophyll peak at 0.56 m (Visible region) and the red edge region (0.67 to 0.72 m; NIR region). This result confirms that the variation induced by the subsurface structures (e.g., stone walls, tile concentrations, pavements near the surface, road networks) to the natural vegetation growth and/or colour (i.e., for different stress factors) is primarily detectable by the chlorophyll peak and the red edge region applied for the vegetation stress detection. Whereas, if dry soils cover the structures (occurrence higher than 75%), both the VNIR and thermal infrared (TIR) regions are suitable to detect the subsurface structures. This work demonstrates that airborne reflectances and emissivities data, even though at different spatial/spectral resolutions and acquisition time represent an effective and rapid tool to detect subsurface structures within different land cover contexts. As concluding results, this study reveals that the airborne multi/hyperspectral image processing can be an effective and cost-efficient tool to perform a preliminary analysis of those areas where large cultural heritage assets prioritising and localizing the sites where to apply near surface geophysics surveys. Spectral Region Spectral Resolution ( m )Spectral Range ( m) Spatial Resolution (m)IFOV (deg) ATM VIS-NIR SWIR-TIR (tot 12 ch) variable from 24 to 3100 0.42 - 1150 2 0.143 CASI VNIR (48 ch.) 0.01 0.40-0.94 2 0.115 MIVIS VNIR (28ch.) 0.02 (VIS) 0.05 (NIR) 0.43-0.83 (VIS) 1.15-1.55 (NIR) 6 - 7 0.115 SWIR (64ch.) 0.09 1.983-2.478 TIR (10ch.) 0.34-0.54 8.180-12.700 Table 1. Characteristics of airborne sensors used for the Arpi test area. 1 References 2 [1] Beck, A., Philip, G., Abdulkarim, M. and Donoghue, D., 2007. Evaluation of Corona and Ikonos high resolution satellite imagery for archaeological prospection in western Syria. Antiquity, 81: 161-175. 3 [2] Altaweel, M., 2005. The Use of ASTER Satellite Imagery in Archaeological Contexts. Archaeological Prospection, 12: 151- 166. 4 [3] Cavalli, R.M.; Colosi, F.; Palombo, A.; Pignatti, S.; Poscolieri, M. Remote hyperspectral imagery as a support to archaeological prospection. J. of Cultural Heritage 2007, 8, 272-283. 5 [4] Kucukkaya, A.G. Photogrammetry and remote sensing in archaeology. J. Quant. Spectrosc. Radiat. Transfer 2004, 97(1-3), 83-97. [5] Rowlands, A.; Sarris, A. Detection of exposed and subsurface archaeological remains using multi-sensor remote sensing. J. of Archaeological Science 2007, 34, 795-803.

Assessment of brine migration risks along vertical pathways due to CO2 injection

NASA Astrophysics Data System (ADS)

Kissinger, Alexander; Class, Holger

2015-04-01

Global climate change, shortage of resources and the growing usage of renewable energy sources has lead to a growing demand for the utilization of subsurface systems. Among these competing uses are Carbon Capture and Storage (CCS), geothermal energy, nuclear waste disposal, 'renewable' methane or hydrogen storage as well as the ongoing production of fossil resources like oil, gas and coal. Additionally, these technologies may also create conflicts with essential public interests such as water supply. For example, the injection of CO2 into the subsurface causes an increase in pressure reaching far beyond the actual radius of influence of the CO2 plume, potentially leading to large amounts of displaced salt water. In this work we focus on the large scale impacts of CO2 storage on brine migration but the methodology and the obtained results may also apply to other fields like waste water disposal, where large amounts of fluid are injected into the subsurface. In contrast to modeling on the reservoir scale the spatial scale required for this work is much larger in both vertical and lateral direction, as the regional hydrogeology has to be considered. Structures such as fault zones, hydrogeological windows in the Rupelian clay or salt domes are considered as potential pathways for displaced fluids into shallow systems and their influence has to be taken into account. We put the focus of our investigations on the latter type of scenario, since there is still a poor understanding of the role that salt diapirs would play in CO2 storage projects. As there is hardly any field data available on this scale, we compare different levels of model complexity in order to identify the relevant processes for brine displacement and simplify the modeling process wherever possible, for example brine injection vs. CO2 injection, simplified geometries vs. the complex formation geometry and the role of salt induced density differences on flow. Further we investigate the impact of the displaced brine due to CO2 injection and compare it to the natural fluid exchange between shallow and deep aquifers in order to asses possible damage.

Australian Multiexperimental Assessment of SIR-B (AMAS)

NASA Technical Reports Server (NTRS)

Richards, J. A.; Forster, B. C.; Milne, A. K.; Taylor, G. R.; Trinder, J. C.

1984-01-01

The utility of SIR-B data for analysis of surface properties and subsurface morphology in three arid regions of Australia is investigated. This study area is located in western New South Wales. It contains extensive aeolian and alluvially derived depositional plains and is the site of the University's Arid Zone Research Station; it is well-mapped and surveyed. Radar backscatter is mapped and evaluated against known terrain conditions. Relative components of surface and subsurface return are determined with a view to identifying structural properties of surface and subsurface morphology. The capability of microwave remote sensing in locating likely groundwater sources in the Bancannia Basin, near Fowler's Gap is assessed.

Resolving carbonate platform geometries on the Island of Bonaire, Caribbean Netherlands through semi-automatic GPR facies classification

NASA Astrophysics Data System (ADS)

Bowling, R. D.; Laya, J. C.; Everett, M. E.

2018-07-01

The study of exposed carbonate platforms provides observational constraints on regional tectonics and sea-level history. In this work Miocene-aged carbonate platform units of the Seroe Domi Formation are investigated on the island of Bonaire, located in the Southern Caribbean. Ground penetrating radar (GPR) was used to probe near-surface structural geometries associated with these lithologies. The single cross-island transect described herein allowed for continuous mapping of geologic structures on kilometre length scales. Numerical analysis was applied to the data in the form of k-means clustering of structure-parallel vectors derived from image structure tensors. This methodology enables radar facies along the survey transect to be semi-automatically mapped. The results provide subsurface evidence to support previous surficial and outcrop observations, and reveal complex stratigraphy within the platform. From the GPR data analysis, progradational clinoform geometries were observed on the northeast side of the island which support the tectonics and depositional trends of the region. Furthermore, several leeward-side radar facies are identified which correlate to environments of deposition conducive to dolomitization via reflux mechanisms.

Resolving Carbonate Platform Geometries on the Island of Bonaire, Caribbean Netherlands through Semi-Automatic GPR Facies Classification

NASA Astrophysics Data System (ADS)

Bowling, R. D.; Laya, J. C.; Everett, M. E.

2018-05-01

The study of exposed carbonate platforms provides observational constraints on regional tectonics and sea-level history. In this work Miocene-aged carbonate platform units of the Seroe Domi Formation are investigated, on the island of Bonaire, located in the Southern Caribbean. Ground penetrating radar (GPR) was used to probe near-surface structural geometries associated with these lithologies. The single cross-island transect described herein allowed for continuous mapping of geologic structures on kilometer length scales. Numerical analysis was applied to the data in the form of k-means clustering of structure-parallel vectors derived from image structure tensors. This methodology enables radar facies along the survey transect to be semi-automatically mapped. The results provide subsurface evidence to support previous surficial and outcrop observations, and reveal complex stratigraphy within the platform. From the GPR data analysis, progradational clinoform geometries were observed on the northeast side of the island which supports the tectonics and depositional trends of the region. Furthermore, several leeward-side radar facies are identified which correlate to environments of deposition conducive to dolomitization via reflux mechanisms.

Scaled Anatomical Model Creation of Biomedical Tomographic Imaging Data and Associated Labels for Subsequent Sub-surface Laser Engraving (SSLE) of Glass Crystals.

PubMed

Betts, Aislinn M; McGoldrick, Matthew T; Dethlefs, Christopher R; Piotrowicz, Justin; Van Avermaete, Tony; Maki, Jeff; Gerstler, Steve; Leevy, W M

2017-04-25

Biomedical imaging modalities like computed tomography (CT) and magnetic resonance (MR) provide excellent platforms for collecting three-dimensional data sets of patient or specimen anatomy in clinical or preclinical settings. However, the use of a virtual, on-screen display limits the ability of these tomographic images to fully convey the anatomical information embedded within. One solution is to interface a biomedical imaging data set with 3D printing technology to generate a physical replica. Here we detail a complementary method to visualize tomographic imaging data with a hand-held model: Sub Surface Laser Engraving (SSLE) of crystal glass. SSLE offers several unique benefits including: the facile ability to include anatomical labels, as well as a scale bar; streamlined multipart assembly of complex structures in one medium; high resolution in the X, Y, and Z planes; and semi-transparent shells for visualization of internal anatomical substructures. Here we demonstrate the process of SSLE with CT data sets derived from pre-clinical and clinical sources. This protocol will serve as a powerful and inexpensive new tool with which to visualize complex anatomical structures for scientists and students in a number of educational and research settings.

Subsurface Hydrologic Processes Revealed by Time-lapse GPR in Two Contrasting Soils in the Shale Hills CZO

NASA Astrophysics Data System (ADS)

Guo, L.; Lin, H.; Nyquist, J.; Toran, L.; Mount, G.

2017-12-01

Linking subsurface structures to their functions in determining hydrologic processes, such as soil moisture dynamics, subsurface flow patterns, and discharge behaviours, is a key to understanding and modelling hydrological systems. Geophysical techniques provide a non-invasive approach to investigate this form-function dualism of subsurface hydrology at the field scale, because they are effective in visualizing subsurface structure and monitoring the distribution of water. In this study, we used time-lapse ground-penetrating radar (GPR) to compare the hydrologic responses of two contrasting soils in the Shale Hills Critical Zone Observatory. By integrating time-lapse GPR with artificial water injection, we observed distinct flow patterns in the two soils: 1) in the deep Rushtown soil (over 1.5 m depth to bedrock) located in a concave hillslope, a lateral preferential flow network extending as far as 2 m downslope was identified above a less permeable layer and via a series of connected macropores; whereas 2) in the shallow Weikert soil ( 0.3 m depth to saprock) located in a planar hillslope, vertical infiltration into the permeable fractured shale dominated the flow field, while the development of lateral preferential flow along the hillslope was restrained. At the Weikert soil site, the addition of brilliant blue dye to the water injection followed by in situ excavation supported GPR interpretation that only limited lateral preferential flow formed along the soil-saprock interface. Moreover, seasonally repeated GPR surveys indicated different patterns of profile moisture distribution in the two soils that in comparison with the dry season, a dense layer within the BC horizon in the deep Rushtown soil prevented vertical infiltration in the wet season, leading to the accumulation of soil moisture above this layer; whereas, in the shallow Weikert soil, water infiltrated into saprock in wet seasons, building up water storage within the fractured bedrock (i.e., the rock moisture). Results of this study demonstrated the strong interplay between soil structures and subsurface hydrologic behaviors, and time-lapse GPR is an effective method to establish such a relationship under the field conditions.

Subsurface Growth Of Silicide Structures In Silicon

NASA Technical Reports Server (NTRS)

Fathauer, Robert W.; George, Thomas; Pike, William T.; Schowalter, Leo

1993-01-01

Technique shows promise for fabrication of novel electronic, optoelectronic, and electro-optical devices. Experiments demonstrated feasibility of growing microscopic single-crystal CoSi2 structures beneath surfaces of Si substrates.

Time-lapse three-dimensional inversion of complex conductivity data using an active time constrained (ATC) approach

USGS Publications Warehouse

Karaoulis, M.; Revil, A.; Werkema, D.D.; Minsley, B.J.; Woodruff, W.F.; Kemna, A.

2011-01-01

Induced polarization (more precisely the magnitude and phase of impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and contaminants in the shallow subsurface. We propose a new time-lapse 3-D modelling and inversion algorithm to image the evolution of complex conductivity over time. We discretize the subsurface using hexahedron cells. Each cell is assigned a complex resistivity or conductivity value. Using the finite-element approach, we model the in-phase and out-of-phase (quadrature) electrical potentials on the 3-D grid, which are then transformed into apparent complex resistivity. Inhomogeneous Dirichlet boundary conditions are used at the boundary of the domain. The calculation of the Jacobian matrix is based on the principles of reciprocity. The goal of time-lapse inversion is to determine the change in the complex resistivity of each cell of the spatial grid as a function of time. Each model along the time axis is called a 'reference space model'. This approach can be simplified into an inverse problem looking for the optimum of several reference space models using the approximation that the material properties vary linearly in time between two subsequent reference models. Regularizations in both space domain and time domain reduce inversion artefacts and improve the stability of the inversion problem. In addition, the use of the time-lapse equations allows the simultaneous inversion of data obtained at different times in just one inversion step (4-D inversion). The advantages of this new inversion algorithm are demonstrated on synthetic time-lapse data resulting from the simulation of a salt tracer test in a heterogeneous random material described by an anisotropic semi-variogram. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

3-D imaging of large scale buried structure by 1-D inversion of very early time electromagnetic (VETEM) data

USGS Publications Warehouse

Aydmer, A.A.; Chew, W.C.; Cui, T.J.; Wright, D.L.; Smith, D.V.; Abraham, J.D.

2001-01-01

A simple and efficient method for large scale three-dimensional (3-D) subsurface imaging of inhomogeneous background is presented. One-dimensional (1-D) multifrequency distorted Born iterative method (DBIM) is employed in the inversion. Simulation results utilizing synthetic scattering data are given. Calibration of the very early time electromagnetic (VETEM) experimental waveforms is detailed along with major problems encountered in practice and their solutions. This discussion is followed by the results of a large scale application of the method to the experimental data provided by the VETEM system of the U.S. Geological Survey. The method is shown to have a computational complexity that is promising for on-site inversion.

Hidden Markov models reveal complexity in the diving behaviour of short-finned pilot whales

PubMed Central

Quick, Nicola J.; Isojunno, Saana; Sadykova, Dina; Bowers, Matthew; Nowacek, Douglas P.; Read, Andrew J.

2017-01-01

Diving behaviour of short-finned pilot whales is often described by two states; deep foraging and shallow, non-foraging dives. However, this simple classification system ignores much of the variation that occurs during subsurface periods. We used multi-state hidden Markov models (HMM) to characterize states of diving behaviour and the transitions between states in short-finned pilot whales. We used three parameters (number of buzzes, maximum dive depth and duration) measured in 259 dives by digital acoustic recording tags (DTAGs) deployed on 20 individual whales off Cape Hatteras, North Carolina, USA. The HMM identified a four-state model as the best descriptor of diving behaviour. The state-dependent distributions for the diving parameters showed variation between states, indicative of different diving behaviours. Transition probabilities were considerably higher for state persistence than state switching, indicating that dive types occurred in bouts. Our results indicate that subsurface behaviour in short-finned pilot whales is more complex than a simple dichotomy of deep and shallow diving states, and labelling all subsurface behaviour as deep dives or shallow dives discounts a significant amount of important variation. We discuss potential drivers of these patterns, including variation in foraging success, prey availability and selection, bathymetry, physiological constraints and socially mediated behaviour. PMID:28361954

Advances in interpretation of subsurface processes with time-lapse electrical imaging

USGS Publications Warehouse

Singha, Kaminit; Day-Lewis, Frederick D.; Johnson, Tim B.; Slater, Lee D.

2015-01-01

Electrical geophysical methods, including electrical resistivity, time-domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time-lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time-lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest.

Advances in interpretation of subsurface processes with time-lapse electrical imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singha, Kamini; Day-Lewis, Frederick D.; Johnson, Timothy C.

2015-03-15

Electrical geophysical methods, including electrical resistivity, time-domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time-lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time-lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest.

High-Resolution Seismic Reflection Profiling Across the Black Hills Fault, Clark County, Nevada: Preliminary Results

NASA Astrophysics Data System (ADS)

Zaragoza, S. A.; Snelson, C. M.; Jernsletten, J. A.; Saldana, S. C.; Hirsch, A.; McEwan, D.

2005-12-01

The Black Hills fault (BHF) is located in the central Basin and Range Province of western North America, a region that has undergone significant Cenozoic extension. The BHF is an east-dipping normal fault that forms the northwestern structural boundary of the Eldorado basin and lies ~20 km southeast of Las Vegas, Nevada. A recent trench study indicated that the fault offsets Holocene strata, and is capable of producing Mw 6.4-6.8 earthquakes. These estimates indicate a subsurface rupture length at least 10 km greater than the length of the scarp. This poses a significant hazard to structures such as the nearby Hoover Dam Bypass Bridge, which is being built to withstand a Mw 6.2-7.0 earthquake on local faults. If the BHF does continue in the subsurface, this structure, as well as nearby communities (Las Vegas, Boulder City, and Henderson), may not be as safe as previously expected. Previous attempts to image the fault with shallow seismics (hammer source) were inconclusive. However, gravity studies imply that the fault continues south of the scarp. Therefore, a new experiment utilizing high-resolution seismic reflection was performed to image subsurface geologic structures south of the scarp. At each shot point, a stack of four 30-160 Hz vibroseis sweeps of 15 s duration was recorded on a 60-channel system with 40 Hz geophones. This produced two 300 m reflection profiles, with a maximum depth of 500-600 m. A preliminary look at these data indicates the existence of two faults, potentially confirming that the BHF continues in the subsurface south of the scarp.

Aseptically Sampled Organics in Subsurface Rocks From the Mars Analog Rio Tinto Experiment: An Analog For The Search for Deep Subsurface Life on Mars.}

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.; Stoker, C. R.

2005-12-01

The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of great relevance to astrobiology including the search for past/present life on Mars. The surface of Mars has conditions preventing current life but the subsurface might preserve organics and even host some life [1]. The Mars-Analog-Rio-Tinto-Experiment (MARTE) is performing a simulation of a Mars drilling experiment. This comprises conventional and robotic drilling of cores in a volcanically-hosted-massive-pyrite deposit [2] from the Iberian Pyritic Belt (IBP) and life detection experiments applying anti-contamination protocols (e.g., ATP Luminometry assay). The RT is considered an important analog of the Sinus Meridiani site on Mars and an ideal model analog for a deep subsurface Martian environment. Former results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and anaerobic chemoautotrophs and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions. A key requirement for the analysis of a subsurface sample on Mars is a set of simple tests that can help determine if the sample contains organic material of biological origin, and its potential for retaining definitive biosignatures. We report here on the presence of bulk organic matter Corg (0.03-0.05 Wt%), and Ntot (0.01-0.04 Wt%) and amount of measured ATP (Lightning MVP, Biocontrol) in weathered rocks (tuffs, gossan, pyrite stockwork from Borehole #8; >166m). This provides key insight on the type of trophic system sustaining the subsurface biosphere (i.e., heterotrophs vs. autotrophs) at RT. ATP data (Relative-Luminosity-Units, RLU) provide information on possible contamination and distribution of viable biomass with core depth (BH#8, and BH#7, ~3m). Avg. 153 RLU, i.e., surface vs. center of core, suggest that cleaness/sterility can be maintained when using a simple sterile protocol under field conditions. Results from this research will support future drilling mission planned on Mars. [1] Boston, P.J., et al., 1992. Icarus 95,300-308; [2] Leistel et al., 1998.

4-D Model of CO2 Deposition at North and South of Mars from HEND/Odyssey and MOLA/MGS

NASA Technical Reports Server (NTRS)

Litvak, M. L.; Mitrofanov, I. G.; Kozyrev, A. S.; Sanin, A. B.; Tretyakov, V.; Smith, D. E.; Zuber, M. T.; Boynton, W. V.; Hamara, D. K.; Shinohara, C.

2003-01-01

The first 1.5 year of neutron mapping measurements onboard Mars Odyssey spacecraft are presented based on High Energy Neutron Detector (HEND) observations. HEND instrument is a part of GRS suite responsible for registration of epithermal and fast neutrons originating in Mars subsurface layer. The scattering of fast neutrons in Mars surface caused by primary cosmic rays is strongly sensitive to presence of hydrogen atoms. Even several percents of subsurface water significantly depress epithermal and fast neutron flux. It turns orbit neutron spectroscopy into one of most efficient methods for finding distribution of subsurface water. The Mars Odyssey observations revealed huge water- ice regions above 60N and 60S latitudes. It was founded that distribution of subsurface water has layered structure at these regions. It is thought that more than 50% wt water ice covered by relatively dry layer with different thickness.

A subsurface depocenter in the South Polar Layered Deposits of Mars

NASA Astrophysics Data System (ADS)

Whitten, J. L.; Campbell, B. A.; Morgan, G. A.

2017-08-01

The South Polar Layered Deposits (SPLD) are one of the largest water ice reservoirs on Mars, and their accumulation is driven by variations in the climate primarily controlled by orbital forcings. Patterns of subsurface layering in the SPLD provide important information about past atmospheric dust content, periods of substantial erosion, and variations in local or regional deposition. Here we analyze the SPLD using SHAllow RADar (SHARAD) sounder data to gain a unique perspective on the interior structure of the deposits and to determine what subsurface layers indicate about the preserved climate history. SHARAD data reveal a major deviation from the gently domical layering typical of the SPLD: a subsurface elongate dome. The dome most likely formed due to variations in the accumulation of ice and snow across the cap, with a higher rate occurring in this region over a prolonged period. This SPLD depositional center provides an important marker of south polar climate patterns.

Two-dimensional resistivity investigation of the North Cavalcade Street site, Houston, Texas, August 2003

USGS Publications Warehouse

Kress, Wade H.; Teeple, Andrew

2005-01-01

Forward modeling was used as an interpretative tool to relate the subsurface distribution of resistivity from four DC resistivity lines to known, assumed, and hypothetical information on subsurface lithologies. The final forward models were used as an estimate of the true resistivity structure for the field data. The forward models and the inversion results of the forward models show the depth, thickness, and extent of strata as well as the resistive anomalies occurring along the four lines and the displacement of strata resulting from the Pecore Fault along two of the four DC resistivity lines. Ten additional DC resistivity lines show similarly distributed shallow subsurface lithologies of silty sand and clay strata. Eight priority areas of resistive anomalies were identified for evaluation in future studies. The interpreted DC resistivity data allowed subsurface stratigraphy to be extrapolated between existing boreholes resulting in an improved understanding of lithologies that can influence contaminant migration.

On the effects of subsurface parameters on evaporite dissolution (Switzerland)

NASA Astrophysics Data System (ADS)

Zidane, Ali; Zechner, Eric; Huggenberger, Peter; Younes, Anis

2014-05-01

Uncontrolled subsurface evaporite dissolution could lead to hazards such as land subsidence. Observed subsidences in a study area of Northwestern Switzerland were mainly due to subsurface dissolution (subrosion) of evaporites such as halite and gypsum. A set of 2D density driven flow simulations were evaluated along 1000 m long and 150 m deep 2D cross sections within the study area that is characterized by tectonic horst and graben structures. The simulations were conducted to study the effect of the different subsurface parameters that could affect the dissolution process. The heterogeneity of normal faults and its impact on the dissolution of evaporites is studied by considering several permeable faults that include non-permeable areas. The mixed finite element method (MFE) is used to solve the flow equation, coupled with the multipoint flux approximation (MPFA) and the discontinuous Galerkin method (DG) to solve the diffusion and the advection parts of the transport equation.

Numerical investigations of internal stresses on carbon steel based on ultrasonic LCR waves

NASA Astrophysics Data System (ADS)

Ramasamy, R.; Ibrahim, Z.; Chai, H. K.

2017-10-01

Internal stresses or residual stresses in the structural elements are very crucial in carrying out in-service evaluations and fitness-for-purpose assessments. The generation of these internal stresses can occur as result of the fabrication of the steel members, installation sequence or other ad-hoc events such as accidents or impact. The accurate prediction of the internal stresses will contribute towards estimating the integrity state of the structural elements, with respect to their material allowable stresses. This paper investigates the explicit FE based numerical modelling of the ultrasonic based non-destructive technique, utilising the measurable longitudinal critical refracted wave (LCR) and relating these to the internal stresses within the structural elements by the evaluation of the material dependent acoustoelastic factors. The subsurface travel path of the LCR wave inside the structural elements makes it a sub-surface stress measurement technique and the linearised relationship with corresponding internal stresses can be systematically applied repeatedly. The numerical results are compared against laboratory tests data to correlate the findings and to establish modelling feasibility for future proof-of-concepts. It can be concluded from this numerical investigation, that the subsurface ultrasonic LCR wave has great potential to be implemented for in-situ structural residual stress measurements, as compared to other available surface measurements such as strain gauges or x-ray diffraction.

Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido —Contact between high-energy physics and volcano physics—

PubMed Central

TANAKA, Hiroyuki K. M.; YOKOYAMA, Izumi

2008-01-01

Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, “pseudo growth curves” of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the “density length” of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics. PMID:18941290

Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido--contact between high-energy physics and volcano physics--.

PubMed

K M Tanaka, Hiroyuki; Yokoyama, Izumi

2008-01-01

Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, "pseudo growth curves" of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the "density length" of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics.

Structure and function of subsurface microbial communities affecting radionuclide transport and bioimmobilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostka, Joel E.; Prakash, Om; Green, Stefan J.

2012-05-01

Our objectives were to: 1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), 2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and 3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations. Field sampling was conducted at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee. Themore » ORFRC subsurface is exposed to mixed contamination predominated by uranium and nitrate. In short, we effectively addressed all 3 stated objectives of the project. In particular, we isolated and characterized a large number of novel anaerobes with a high bioremediation potential that can be used as model organisms, and we are now able to quantify the function of subsurface sedimentary microbial communities in situ using state-of-the-art gene expression methods (molecular proxies).« less

Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

NASA Technical Reports Server (NTRS)

Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

2009-01-01

A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

Detection of subsurface-intensified eddies from observations of the sea-surface: a case study for Mediterranean Water Eddies in a long-term high-resolution simulation

NASA Astrophysics Data System (ADS)

Ciani, Daniele; Carton, Xavier; Barbosa Aguiar, Ana Claudia; Peliz, Alvaro; Bashmachnikov, Igor; Ienna, Federico; Chapron, Bertrand

2017-04-01

Subsurface-intensified eddies are ubiquitous in the world ocean. They can be generated by exchanges of water masses between semi-enclosed evaporation basins and the open ocean or by deep convection. Past and recent studies have shown that these eddies are carriers of large amounts of heat and salt, that they are coherent over inter-annual timescales and that they can migrate for several thousands of miles from their origination areas towards the open ocean. Hence, subsurface-intensified eddies can influence the three-dimensional distribution of oceanic tracers at global scale. The synoptic knowledge of the eddies positions and mean pathways is then crucial for evaluating temperature and salinity budgets in the world ocean. At present day, satellite sensors constitute the ideal tool for the synoptic and global scale observations of the ocean. Since they only provide informations on the oceanic surface, we characterized the signatures that subsurface eddies generate at the sea-surface, to determine the extent to which they can be isolated from the surrounding surface turbulence and be considered as a trace of an underlying eddy. We studied the surface signature of subsurface-intensified anticyclones (Mediterranean Water Eddies - Meddies) in a realistic, long-term (20 years) and high resolution simulation (dx = 3 km) based on the ROMS model. The novelty and advantage of this approach is given by the simultaneous availability of the full 3D eddies characteristics, the ones of the background ocean and of the sea-surface (in terms of sea-surface height, temperature and salinity). This also allowed us to speculate on a synergy between different satellite observations for the automatic detection of subsurface eddies from space. The along trajectory properties and surface signatures of more than 90 long-lived Meddies were analyzed. We showed that the Meddies constantly generate positive anomalies in sea-surface height and that these anomalies are principally related to the Meddy potential vorticity structure at depth (around 1000 m below the sea-surface). Such anomalies were long-lived, mostly migrated exhibiting southwestward trajectories, their intensities were O(10 cm) and extended horizontally up to more than 300 km (around 1.5 times the Meddy diameter). On the other hand, the Meddies thermohaline surface signatures proved to be mostly dominated by the local surface conditions and their structure poorly correlated to the Meddy structure at depth (e.g. the Meddy volume-integrated salt and temperature content). These results point out that satellite altimetry is the most suitable approach to track subsurface-intensified eddies from observations of the sea-surface, also encouraging the use of future high-resolution altimetric observations (e.g. SWOT) to detect subsurface oceanic motions from satellite sensors.

Evaluating the importance of characterizing soil structure and horizons in parameterizing a hydrologic process model

USGS Publications Warehouse

Mirus, Benjamin B.

2015-01-01

Incorporating the influence of soil structure and horizons into parameterizations of distributed surface water/groundwater models remains a challenge. Often, only a single soil unit is employed, and soil-hydraulic properties are assigned based on textural classification, without evaluating the potential impact of these simplifications. This study uses a distributed physics-based model to assess the influence of soil horizons and structure on effective parameterization. This paper tests the viability of two established and widely used hydrogeologic methods for simulating runoff and variably saturated flow through layered soils: (1) accounting for vertical heterogeneity by combining hydrostratigraphic units with contrasting hydraulic properties into homogeneous, anisotropic units and (2) use of established pedotransfer functions based on soil texture alone to estimate water retention and conductivity, without accounting for the influence of pedon structures and hysteresis. The viability of this latter method for capturing the seasonal transition from runoff-dominated to evapotranspiration-dominated regimes is also tested here. For cases tested here, event-based simulations using simplified vertical heterogeneity did not capture the state-dependent anisotropy and complex combinations of runoff generation mechanisms resulting from permeability contrasts in layered hillslopes with complex topography. Continuous simulations using pedotransfer functions that do not account for the influence of soil structure and hysteresis generally over-predicted runoff, leading to propagation of substantial water balance errors. Analysis suggests that identifying a dominant hydropedological unit provides the most acceptable simplification of subsurface layering and that modified pedotransfer functions with steeper soil-water retention curves might adequately capture the influence of soil structure and hysteresis on hydrologic response in headwater catchments.

Final Project Report: Imaging Fault Zones Using a Novel Elastic Reverse-Time Migration Imaging Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lianjie; Chen, Ting; Tan, Sirui

Imaging fault zones and fractures is crucial for geothermal operators, providing important information for reservoir evaluation and management strategies. However, there are no existing techniques available for directly and clearly imaging fault zones, particularly for steeply dipping faults and fracture zones. In this project, we developed novel acoustic- and elastic-waveform inversion methods for high-resolution velocity model building. In addition, we developed acoustic and elastic reverse-time migration methods for high-resolution subsurface imaging of complex subsurface structures and steeply-dipping fault/fracture zones. We first evaluated and verified the improved capabilities of our newly developed seismic inversion and migration imaging methods using synthetic seismicmore » data. Our numerical tests verified that our new methods directly image subsurface fracture/fault zones using surface seismic reflection data. We then applied our novel seismic inversion and migration imaging methods to a field 3D surface seismic dataset acquired at the Soda Lake geothermal field using Vibroseis sources. Our migration images of the Soda Lake geothermal field obtained using our seismic inversion and migration imaging algorithms revealed several possible fault/fracture zones. AltaRock Energy, Inc. is working with Cyrq Energy, Inc. to refine the geologic interpretation at the Soda Lake geothermal field. Trenton Cladouhos, Senior Vice President R&D of AltaRock, was very interested in our imaging results of 3D surface seismic data from the Soda Lake geothermal field. He planed to perform detailed interpretation of our images in collaboration with James Faulds and Holly McLachlan of University of Nevada at Reno. Using our high-resolution seismic inversion and migration imaging results can help determine the optimal locations to drill wells for geothermal energy production and reduce the risk of geothermal exploration.« less

A multiple-point geostatistical method for characterizing uncertainty of subsurface alluvial units and its effects on flow and transport

USGS Publications Warehouse

Cronkite-Ratcliff, C.; Phelps, G.A.; Boucher, A.

2012-01-01

This report provides a proof-of-concept to demonstrate the potential application of multiple-point geostatistics for characterizing geologic heterogeneity and its effect on flow and transport simulation. The study presented in this report is the result of collaboration between the U.S. Geological Survey (USGS) and Stanford University. This collaboration focused on improving the characterization of alluvial deposits by incorporating prior knowledge of geologic structure and estimating the uncertainty of the modeled geologic units. In this study, geologic heterogeneity of alluvial units is characterized as a set of stochastic realizations, and uncertainty is indicated by variability in the results of flow and transport simulations for this set of realizations. This approach is tested on a hypothetical geologic scenario developed using data from the alluvial deposits in Yucca Flat, Nevada. Yucca Flat was chosen as a data source for this test case because it includes both complex geologic and hydrologic characteristics and also contains a substantial amount of both surface and subsurface geologic data. Multiple-point geostatistics is used to model geologic heterogeneity in the subsurface. A three-dimensional (3D) model of spatial variability is developed by integrating alluvial units mapped at the surface with vertical drill-hole data. The SNESIM (Single Normal Equation Simulation) algorithm is used to represent geologic heterogeneity stochastically by generating 20 realizations, each of which represents an equally probable geologic scenario. A 3D numerical model is used to simulate groundwater flow and contaminant transport for each realization, producing a distribution of flow and transport responses to the geologic heterogeneity. From this distribution of flow and transport responses, the frequency of exceeding a given contaminant concentration threshold can be used as an indicator of uncertainty about the location of the contaminant plume boundary.

Stochastic Seismic Inversion and Migration for Offshore Site Investigation in the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Son, J.; Medina-Cetina, Z.

2017-12-01

We discuss the comparison between deterministic and stochastic optimization approaches to the nonlinear geophysical full-waveform inverse problem, based on the seismic survey data from Mississippi Canyon in the Northern Gulf of Mexico. Since the subsea engineering and offshore construction projects actively require reliable ground models from various site investigations, the primary goal of this study is to reconstruct the accurate subsurface information of the soil and rock material profiles under the seafloor. The shallow sediment layers have naturally formed heterogeneous formations which may cause unwanted marine landslides or foundation failures of underwater infrastructure. We chose the quasi-Newton and simulated annealing as deterministic and stochastic optimization algorithms respectively. Seismic forward modeling based on finite difference method with absorbing boundary condition implements the iterative simulations in the inverse modeling. We briefly report on numerical experiments using a synthetic data as an offshore ground model which contains shallow artificial target profiles of geomaterials under the seafloor. We apply the seismic migration processing and generate Voronoi tessellation on two-dimensional space-domain to improve the computational efficiency of the imaging stratigraphical velocity model reconstruction. We then report on the detail of a field data implementation, which shows the complex geologic structures in the Northern Gulf of Mexico. Lastly, we compare the new inverted image of subsurface site profiles in the space-domain with the previously processed seismic image in the time-domain at the same location. Overall, stochastic optimization for seismic inversion with migration and Voronoi tessellation show significant promise to improve the subsurface imaging of ground models and improve the computational efficiency required for the full waveform inversion. We anticipate that by improving the inversion process of shallow layers from geophysical data will better support the offshore site investigation.

Implications of Polishing Techniques in Quantitative X-Ray Microanalysis

PubMed Central

Rémond, Guy; Nockolds, Clive; Phillips, Matthew; Roques-Carmes, Claude

2002-01-01

Specimen preparation using abrasives results in surface and subsurface mechanical (stresses, strains), geometrical (roughness), chemical (contaminants, reaction products) and physical modifications (structure, texture, lattice defects). The mechanisms involved in polishing with abrasives are presented to illustrate the effects of surface topography, surface and subsurface composition and induced lattice defects on the accuracy of quantitative x-ray microanalysis of mineral materials with the electron probe microanalyzer (EPMA). PMID:27446758

Phylogenetic and Functional Diversity of Microbial Communities Associated with Subsurface Sediments of the Sonora Margin, Guaymas Basin

PubMed Central

Vigneron, Adrien; Cruaud, Perrine; Roussel, Erwan G.; Pignet, Patricia; Caprais, Jean-Claude; Callac, Nolwenn; Ciobanu, Maria-Cristina; Godfroy, Anne; Cragg, Barry A.; Parkes, John R.; Van Nostrand, Joy D.; He, Zhili; Zhou, Jizhong; Toffin, Laurent

2014-01-01

Subsurface sediments of the Sonora Margin (Guaymas Basin), located in proximity of active cold seep sites were explored. The taxonomic and functional diversity of bacterial and archaeal communities were investigated from 1 to 10 meters below the seafloor. Microbial community structure and abundance and distribution of dominant populations were assessed using complementary molecular approaches (Ribosomal Intergenic Spacer Analysis, 16S rRNA libraries and quantitative PCR with an extensive primers set) and correlated to comprehensive geochemical data. Moreover the metabolic potentials and functional traits of the microbial community were also identified using the GeoChip functional gene microarray and metabolic rates. The active microbial community structure in the Sonora Margin sediments was related to deep subsurface ecosystems (Marine Benthic Groups B and D, Miscellaneous Crenarchaeotal Group, Chloroflexi and Candidate divisions) and remained relatively similar throughout the sediment section, despite defined biogeochemical gradients. However, relative abundances of bacterial and archaeal dominant lineages were significantly correlated with organic carbon quantity and origin. Consistently, metabolic pathways for the degradation and assimilation of this organic carbon as well as genetic potentials for the transformation of detrital organic matters, hydrocarbons and recalcitrant substrates were detected, suggesting that chemoorganotrophic microorganisms may dominate the microbial community of the Sonora Margin subsurface sediments. PMID:25099369

An intermediate-scale model for thermal hydrology in low-relief permafrost-affected landscapes

DOE PAGES

Jan, Ahmad; Coon, Ethan T.; Painter, Scott L.; ...

2017-07-10

Integrated surface/subsurface models for simulating the thermal hydrology of permafrost-affected regions in a warming climate have recently become available, but computational demands of those new process-rich simu- lation tools have thus far limited their applications to one-dimensional or small two-dimensional simulations. We present a mixed-dimensional model structure for efficiently simulating surface/subsurface thermal hydrology in low-relief permafrost regions at watershed scales. The approach replaces a full three-dimensional system with a two-dimensional overland thermal hydrology system and a family of one-dimensional vertical columns, where each column represents a fully coupled surface/subsurface thermal hydrology system without lateral flow. The system is then operatormore » split, sequentially updating the overland flow system without sources and the one-dimensional columns without lateral flows. We show that the app- roach is highly scalable, supports subcycling of different processes, and compares well with the corresponding fully three-dimensional representation at significantly less computational cost. Those advances enable recently developed representations of freezing soil physics to be coupled with thermal overland flow and surface energy balance at scales of 100s of meters. Furthermore developed and demonstrated for permafrost thermal hydrology, the mixed-dimensional model structure is applicable to integrated surface/subsurface thermal hydrology in general.« less

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processesmore » receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. Furthermore, the results also demonstrate the sensitivity of surface based ERT measurements to those changes over time.« less

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

DOE PAGES

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

2016-09-22

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processesmore » receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. Furthermore, the results also demonstrate the sensitivity of surface based ERT measurements to those changes over time.« less

Dense Nonaqueous Phase Liquids at Former Manufactured Gas Plants: Challenges to Modeling and Remediation

PubMed Central

Birak, P.S.; Miller, C.T.

2008-01-01

The remediation of dense non-aqueous phase liquids (DNAPLs) in porous media continues to be one of the most challenging problems facing environmental scientists and engineers. Of all the environmentally relevant DNAPLs, tars in the subsurface at former manufactured gas plants (FMGP’s) pose one of the biggest challenges due to their complex chemical composition and tendency to alter wettability. To further our understanding of these complex materials, we consulted historic documentation to evaluate the impact of gas manufacturing on the composition and physicochemical nature of the resulting tars. In the recent literature, most work to date has been focused in a relatively narrow portion of the expected range of tar materials, which has yielded a bias toward samples of relatively low viscosity and density. In this work, we consider the dissolution and movement of tars in the subsurface, models used to predict these phenomena, and approaches used for remediation. We also explore the open issues and detail important gaps in our fundamental understanding of these extraordinarily complex systems that must be resolved to reach a mature level of understanding. PMID:19176266

Forensic Assessment on Ground Instability Using Electrical Resistivity Imaging (ERI)

NASA Astrophysics Data System (ADS)

Hazreek, Z. A. M.; Azhar, A. T. S.; Aziman, M.; Fauzan, S. M. S. A.; Ikhwan, J. M.; Aishah, M. A. N.

2017-02-01

Electrical resistivity imaging (ERI) was used to evaluate the ground settlement in local scale at housing areas. ERI and Borehole results were used to interpret the condition of the problematic subsurface profile due to its differential stiffness. Electrical resistivity of the subsurface profile was measured using ABEM SAS4000 equipment set. ERI results using electrical resistivity anomaly on subsurface materials resistivity shows the subsurface profile exhibited low (1 - 100 Ωm) and medium (> 100 Ωm) value (ERV) representing weak to firm materials. The occurrences of soft to medium cohesive material (SPT N value = 2 - 7) and stiff cohesive material (SPT N ≥ 8) in local scale has created inconsistency of the ground stability condition. Moreover, it was found that a layer of organic decayed wood (ERV = 43 ˜ 29 Ωm & SPT N = 15 ˜ 9) has been buried within the subsurface profile thus weaken the ground structure and finally promoting to the ground settlement. The heterogeneous of the subsurface material presented using integrated analysis of ERI and borehole data enabled ground settlement in this area to be evaluated. This is the major factor evaluating ground instability in the local scale. The result was applicable to assist in planning a strategy for sustainable ground improvement of local scale in fast, low cost, and large data coverage.

How much can we trust a geological model underlying a subsurface hydrological investigation?

NASA Astrophysics Data System (ADS)

Wellmann, Florian; de la Varga, Miguel; Schaaf, Alexander; Burs, David

2017-04-01

Geological models often provide an important basis for subsequent hydrological investigations. As these models are generally built with a limited amount of information, they can contain significant uncertainties - and it is reasonable to assume that these uncertainties can potentially influence subsequent hydrological simulations. However, the investigation of uncertainties in geological models is not straightforward - and, even though recent advances have been made in the field, there is no out-of-the-box implementation to analyze uncertainties in a standard geological modeling package. We present here results of recent developments to address this problem with an efficient implementation of a geological modeling method for complex structural models, integrated in a Bayesian inference framework. The implemented geological modeling approach is based on a full 3-D implicit interpolation that directly respects interface positions and orientation measurements, as well as the influence of faults. In combination, the approach allows us to generate ensembles of geological model realizations, constrained by additional information in the form of likelihood functions to ensure consistency with additional geological aspects (e.g. sequence continuity, topology, fault network consistency), and we demonstrate the potential of the method in an exemplified case study. With this approach, we aim to contribute to a better understanding of the influence of geological uncertainties on subsurface hydrological investigations.

Potential for microbial H2 and metal transformations associated with novel bacteria and archaea in deep terrestrial subsurface sediments

PubMed Central

Hernsdorf, Alex W; Amano, Yuki; Miyakawa, Kazuya; Ise, Kotaro; Suzuki, Yohey; Anantharaman, Karthik; Probst, Alexander; Burstein, David; Thomas, Brian C; Banfield, Jillian F

2017-01-01

Geological sequestration in deep underground repositories is the prevailing proposed route for radioactive waste disposal. After the disposal of radioactive waste in the subsurface, H2 may be produced by corrosion of steel and, ultimately, radionuclides will be exposed to the surrounding environment. To evaluate the potential for microbial activities to impact disposal systems, we explored the microbial community structure and metabolic functions of a sediment-hosted ecosystem at the Horonobe Underground Research Laboratory, Hokkaido, Japan. Overall, we found that the ecosystem hosted organisms from diverse lineages, including many from the phyla that lack isolated representatives. The majority of organisms can metabolize H2, often via oxidative [NiFe] hydrogenases or electron-bifurcating [FeFe] hydrogenases that enable ferredoxin-based pathways, including the ion motive Rnf complex. Many organisms implicated in H2 metabolism are also predicted to catalyze carbon, nitrogen, iron and sulfur transformations. Notably, iron-based metabolism is predicted in a novel lineage of Actinobacteria and in a putative methane-oxidizing ANME-2d archaeon. We infer an ecological model that links microorganisms to sediment-derived resources and predict potential impacts of microbial activity on H2 consumption and retardation of radionuclide migration. PMID:28350393

Molecular evidence of Late Archean archaea and the presence of a subsurface hydrothermal biosphere

PubMed Central

Ventura, Gregory T.; Kenig, Fabien; Reddy, Christopher M.; Schieber, Juergen; Frysinger, Glenn S.; Nelson, Robert K.; Dinel, Etienne; Gaines, Richard B.; Schaeffer, Philippe

2007-01-01

Highly cracked and isomerized archaeal lipids and bacterial lipids, structurally changed by thermal stress, are present in solvent extracts of 2,707- to 2,685-million-year-old (Ma) metasedimentary rocks from Timmins, ON, Canada. These lipids appear in conventional gas chromatograms as unresolved complex mixtures and include cyclic and acyclic biphytanes, C36–C39 derivatives of the biphytanes, and C31–C35 extended hopanes. Biphytane and extended hopanes are also found in high-pressure catalytic hydrogenation products released from solvent-extracted sediments, indicating that archaea and bacteria were present in Late Archean sedimentary environments. Postdepositional, hydrothermal gold mineralization and graphite precipitation occurred before metamorphism (≈2,665 Ma). Late Archean metamorphism significantly reduced the kerogen's adsorptive capacity and severely restricted sediment porosity, limiting the potential for post-Archean additions of organic matter to the samples. Argillites exposed to hydrothermal gold mineralization have disproportionately high concentrations of extractable archaeal and bacterial lipids relative to what is releasable from their respective high-pressure catalytic hydrogenation product and what is observed for argillites deposited away from these hydrothermal settings. The addition of these lipids to the sediments likely results from a Late Archean subsurface hydrothermal biosphere of archaea and bacteria. PMID:17726114

Molecular dynamics simulations of uranyl adsorption and structure on the basal surface of muscovite

DOE PAGES

Teich-McGoldrick, Stephanie L.; Greathouse, Jeffery A.; Cygan, Randall T.

2014-02-05

Anthropogenic activities have led to an increased concentration of uranium on the Earth’s surface and potentially in the subsurface with the development of nuclear waste repositories. Uranium is soluble in groundwater, and its mobility is strongly affected by the presence of clay minerals in soils and in subsurface sediments. We use molecular dynamics simulations to probe the adsorption of aqueous uranyl (UO 2 2+) ions onto the basal surface of muscovite, a suitable proxy for typically ultrafine-grained clay phases. Model systems include the competitive adsorption between potassium counterions and aqueous ions (0.1 M and 1.0 M UO 2Cl 2 ,more » 0.1 M NaCl). We find that for systems with potassium and uranyl ions present, potassium ions dominate the adsorption phenomenon. Potassium ions adsorb entirely as inner-sphere complexes associated with the ditrigonal cavity of the basal surface. Uranyl ions adsorb in two configurations when it is the only ion species present, and in a single configuration in the presence of potassium. Finally, the majority of adsorbed uranyl ions are tilted less than 45° relative to the muscovite surface, and are associated with the Si 4Al 2 rings near aluminum substitution sites.« less

Reconstructing the Vulcano Island evolution from 3D modeling of magnetic signatures

NASA Astrophysics Data System (ADS)

Napoli, Rosalba; Currenti, Gilda

2016-06-01

High-resolution ground and marine magnetic data are exploited for a detailed definition of a 3D model of the Vulcano Island volcanic complex. The resulting 3D magnetic imaging, obtained by 3-D inverse modeling technique, has delivered useful constraints both to reconstruct the Vulcano Island evolution and to be used as input data for volcanic hazard assessment models. Our results constrained the depth and geometry of the main geo-structural features revealing more subsurface volcanic structures than exposed ones and allowing to elucidate the relationships between them. The recognition of two different magnetization sectors, approximatively coincident with the structural depressions of Piano caldera, in the southern half of the island, and La Fossa caldera at the north, suggests a complex structural and volcanic evolution. Magnetic highs identified across the southern half of the island reflect the main crystallized feeding systems, intrusions and buried vents, whose NNW-SSE preferential alignment highlights the role of the NNW-SSE Tindari-Letojanni regional system from the initial activity of the submarine edifice, to the more recent activity of the Vulcano complex. The low magnetization area, in the middle part of the island may result from hydrothermally altered rocks. Their presence not only in the central part of the volcano edifice but also in other peripheral areas, is a sign of a more diffuse historical hydrothermal activity than in present days. Moreover, the high magnetization heterogeneity within the upper flanks of La Fossa cone edifice is an imprint of a composite distribution of unaltered and altered rocks with different mechanical properties, which poses in this area a high risk level for failure processes especially during volcanic or hydrothermal crisis.

A new approach to define surface/sub-surface transition in gravel beds

NASA Astrophysics Data System (ADS)

Haynes, Heather; Ockelford, Anne-Marie; Vignaga, Elisa; Holmes, William

2012-12-01

The vertical structure of river beds varies temporally and spatially in response to hydraulic regime, sediment mobility, grain size distribution and faunal interaction. Implicit are changes to the active layer depth and bed porosity, both critical in describing processes such as armour layer development, surface-subsurface exchange processes and siltation/ sealing. Whilst measurements of the bed surface are increasingly informed by quantitative and spatial measurement techniques (e.g., laser displacement scanning), material opacity has precluded the full 3D bed structure analysis required to accurately define the surface-subsurface transition. To overcome this problem, this paper provides magnetic resonance imaging (MRI) data of vertical bed porosity profiles. Uniform and bimodal (σ g = 2.1) sand-gravel beds are considered following restructuring under sub-threshold flow durations of 60 and 960 minutes. MRI data are compared to traditional 2.5D laser displacement scans and six robust definitions of the surface-subsurface transition are provided; these form the focus of discussion.

Enhancement of subsurface geologic structure model based on gravity, magnetotelluric, and well log data in Kamojang geothermal field

NASA Astrophysics Data System (ADS)

Yustin Kamah, Muhammad; Armando, Adilla; Larasati Rahmani, Dinda; Paramitha, Shabrina

2017-12-01

Geophysical methods such as gravity and magnetotelluric methods commonly used in conventional and unconventional energy exploration, notably for exploring geothermal prospect. They used to identify the subsurface geology structures which is estimated as a path of fluid flow. This study was conducted in Kamojang Geothermal Field with the aim of highlighting the volcanic lineament in West Java, precisely in Guntur-Papandayan chain where there are three geothermal systems. Kendang Fault has predominant direction NE-SW, identified by magnetotelluric techniques and gravity data processing techniques. Gravity techniques such as spectral analysis, derivative solutions, and Euler deconvolution indicate the type and geometry of anomaly. Magnetotelluric techniques such as inverse modeling and polar diagram are required to know subsurface resistivity charactersitics and major orientation. Furthermore, the result from those methods will be compared to geology information and some section of well data, which is sufficiently suitable. This research is very useful to trace out another potential development area.

Can Computational Sediment Transport Models Reproduce the Observed Variability of Channel Networks in Modern Deltas?

NASA Astrophysics Data System (ADS)

Nesvold, E.; Mukerji, T.

2017-12-01

River deltas display complex channel networks that can be characterized through the framework of graph theory, as shown by Tejedor et al. (2015). Deltaic patterns may also be useful in a Bayesian approach to uncertainty quantification of the subsurface, but this requires a prior distribution of the networks of ancient deltas. By considering subaerial deltas, one can at least obtain a snapshot in time of the channel network spectrum across deltas. In this study, the directed graph structure is semi-automatically extracted from satellite imagery using techniques from statistical processing and machine learning. Once the network is labeled with vertices and edges, spatial trends and width and sinuosity distributions can also be found easily. Since imagery is inherently 2D, computational sediment transport models can serve as a link between 2D network structure and 3D depositional elements; the numerous empirical rules and parameters built into such models makes it necessary to validate the output with field data. For this purpose we have used a set of 110 modern deltas, with average water discharge ranging from 10 - 200,000 m3/s, as a benchmark for natural variability. Both graph theoretic and more general distributions are established. A key question is whether it is possible to reproduce this deltaic network spectrum with computational models. Delft3D was used to solve the shallow water equations coupled with sediment transport. The experimental setup was relatively simple; incoming channelized flow onto a tilted plane, with varying wave and tidal energy, sediment types and grain size distributions, river discharge and a few other input parameters. Each realization was run until a delta had fully developed: between 50 and 500 years (with a morphology acceleration factor). It is shown that input parameters should not be sampled independently from the natural ranges, since this may result in deltaic output that falls well outside the natural spectrum. Since we are interested in studying the patterns occurring in nature, ideas are proposed for how to sample computer realizations that match this distribution. By establishing a link between surface based patterns from the field with the associated subsurface structure from physics-based models, this is a step towards a fully Bayesian workflow in subsurface simulation.

Integrating experimental and numerical methods for a scenario-based quantitative assessment of subsurface energy storage options

NASA Astrophysics Data System (ADS)

Kabuth, Alina; Dahmke, Andreas; Hagrey, Said Attia al; Berta, Márton; Dörr, Cordula; Koproch, Nicolas; Köber, Ralf; Köhn, Daniel; Nolde, Michael; Tilmann Pfeiffer, Wolf; Popp, Steffi; Schwanebeck, Malte; Bauer, Sebastian

2016-04-01

Within the framework of the transition to renewable energy sources ("Energiewende"), the German government defined the target of producing 60 % of the final energy consumption from renewable energy sources by the year 2050. However, renewable energies are subject to natural fluctuations. Energy storage can help to buffer the resulting time shifts between production and demand. Subsurface geological structures provide large potential capacities for energy stored in the form of heat or gas on daily to seasonal time scales. In order to explore this potential sustainably, the possible induced effects of energy storage operations have to be quantified for both specified normal operation and events of failure. The ANGUS+ project therefore integrates experimental laboratory studies with numerical approaches to assess subsurface energy storage scenarios and monitoring methods. Subsurface storage options for gas, i.e. hydrogen, synthetic methane and compressed air in salt caverns or porous structures, as well as subsurface heat storage are investigated with respect to site prerequisites, storage dimensions, induced effects, monitoring methods and integration into spatial planning schemes. The conceptual interdisciplinary approach of the ANGUS+ project towards the integration of subsurface energy storage into a sustainable subsurface planning scheme is presented here, and this approach is then demonstrated using the examples of two selected energy storage options: Firstly, the option of seasonal heat storage in a shallow aquifer is presented. Coupled thermal and hydraulic processes induced by periodic heat injection and extraction were simulated in the open-source numerical modelling package OpenGeoSys. Situations of specified normal operation as well as cases of failure in operational storage with leaking heat transfer fluid are considered. Bench-scale experiments provided parameterisations of temperature dependent changes in shallow groundwater hydrogeochemistry. As a second example, the option of seasonal hydrogen storage in a deep saline aquifer is considered. The induced thermal and hydraulic multiphase flow processes were simulated. Also, an integrative approach towards geophysical monitoring of gas presence was evaluated by synthetically applying these monitoring methods to the synthetic, however realistically defined numerical storage scenarios. Laboratory experiments provided parameterisations of geochemical effects caused by storage gas leakage into shallow aquifers in cases of sealing failure. Ultimately, the analysis of realistically defined scenarios of subsurface energy storage within the ANGUS+ project allows a quantification of the subsurface space claimed by a storage operation and its induced effects. Acknowledgments: This work is part of the ANGUS+ project (www.angusplus.de) and funded by the German Federal Ministry of Education and Research (BMBF) as part of the energy storage initiative "Energiespeicher".

Paleokarst processes in the Eocene limestones of the Pyramids Plateau, Giza, Egypt

NASA Astrophysics Data System (ADS)

El Aref, M. M.; Refai, E.

The Eocene limestones of the Pyramids plateau are characterized by landforms of stepped terraced escarpment and karst ridges with isolated hills. The carbonate country rocks are also dominated by minor surface, surface to subsurface and subsurface solution features associated with karst products. The systematic field observations eludicate the denudation trend of the minor solution features and suggest the origin of the regional landscapes. The lithologic and structural characters of the limestone country rocks comprise the main factors controlling the surface and subsurface karst evolution. The development of the karst features and the associated sediments in the study area provides information on the paleohydrolic, chemical and climatic environments involved in the origin of the karstification.

Different integrated geophysical approaches to investigate archaeological sites in urban and suburban area.

NASA Astrophysics Data System (ADS)

Piro, Salvatore; Papale, Enrico; Zamuner, Daniela

2016-04-01

Geophysical methods are frequently used in archaeological prospection in order to provide detailed information about the presence of structures in the subsurface as well as their position and their geometrical reconstruction, by measuring variations of some physical properties. Often, due to the limited size and depth of an archaeological structure, it may be rather difficult to single out its position and extent because of the generally low signal-to-noise ratio. This problem can be overcome by improving data acquisition, processing techniques and by integrating different geophysical methods. In this work, two sites of archaeological interest, were investigated employing several methods (Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT), Fluxgate Differential Magnetic) to obtain precise and detailed maps of subsurface bodies. The first site, situated in a suburban area between Itri and Fondi, in the Aurunci Natural Regional Park (Central Italy), is characterized by the presence of remains of past human activity dating from the third century B.C. The second site, is instead situated in an urban area in the city of Rome (Basilica di Santa Balbina), where historical evidence is also present. The methods employed, allowed to determine the position and the geometry of some structures in the subsurface related to this past human activity. To have a better understanding of the subsurface, we then performed a qualitative and quantitative integration of this data, which consists in fusing the data from all the methods used, to have a complete visualization of the investigated area. Qualitative integration consists in graphically overlaying the maps obtained by the single methods; this method yields only images, not new data that may be subsequently analyzed. Quantitative integration is instead performed by mathematical and statistical solutions, which allows to have a more accurate reconstruction of the subsurface and generates new data with high information content.

A survey of surface structures and subsurface developments for lunar bases

NASA Technical Reports Server (NTRS)

Hypes, Warren D.; Wright, Robert L.

1990-01-01

Concepts proposed for lunar-base structures and shelters include those fabricated on earth, fabricated locally using lunar materials, and developed from subsurface features. Early bases may rely on evolutionary growth using Space Station modules and nodes covered with regolith for protection against thermal and radiative stresses. Expandable/inflatable shelters used alone on the surface or in conjunction with subselene (beneath the lunar surface) features and spent portions of the Space Shuttle's fuel tanks offer early alternatives. More mature lunar bases may need larger volumes provided by erectable buildings, hybrid inflatable/rigid spheres, modular concrete buildings using locally derived cement, or larger subselene developments.

Deformation band clusters on Mars and implications for subsurface fluid flow

USGS Publications Warehouse

Okubo, C.H.; Schultz, R.A.; Chan, M.A.; Komatsu, G.

2009-01-01

High-resolution imagery reveals unprecedented lines of evidence for the presence of deformation band clusters in layered sedimentary deposits in the equatorial region of Mars. Deformation bands are a class of geologic structural discontinuity that is a precursor to faults in clastic rocks and soils. Clusters of deformation bands, consisting of many hundreds of individual subparallel bands, can act as important structural controls on subsurface fluid flow in terrestrial reservoirs, and evidence of diagenetic processes is often preserved along them. Deformation band clusters are identified on Mars based on characteristic meter-scale architectures and geologic context as observed in data from the High-Resolution Imaging Science Experiment (HiRISE) camera. The identification of deformation band clusters on Mars is a key to investigating the migration of fluids between surface and subsurface reservoirs in the planet's vast sedimentary deposits. Similar to terrestrial examples, evidence of diagenesis in the form of light- and dark-toned discoloration and wall-rock induration is recorded along many of the deformation band clusters on Mars. Therefore, these structures are important sites for future exploration and investigations into the geologic history of water and water-related processes on Mars. ?? 2008 Geological Society of America.

Spatially resolved, diffuse reflectance imaging for subsurface pattern visualization toward development of a lensless imaging platform: phantom experiments

NASA Astrophysics Data System (ADS)

Schelkanova, Irina; Pandya, Aditya; Saiko, Guennadi; Nacy, Lidia; Babar, Hannan; Shah, Duoaud; Lilge, Lothar; Douplik, Alexandre

2016-01-01

A portable, spatially resolved, diffuse reflectance lensless imaging technique based on the charge-coupled device or complementary metal-oxide semiconductor sensor directly coupled to the fiber optic bundle is proposed for visualization of subsurface structures such as superficial microvasculature in the epithelium. We discuss an experimental method for emulating a lensless imaging setup via raster scanning a single fiber-optic cable over a microfluidic phantom containing periodic hemoglobin absorption contrast. To evaluate the ability of the technique to recover information about the subsurface linear structures, scattering layers formed of the Sylgard® 184 Silicone Elastomer and titanium dioxide were placed atop the microfluidic phantom. Thickness of the layers ranged from 0.2 to 0.7 mm, and the values of the reduced scattering coefficient (μs‧) were between 0.85 and 4.25 mm-1. The results demonstrate that fiber-optic, lensless platform can be used for two-dimensional imaging of absorbing inclusions in diffuse reflectance mode. In these experiments, it was shown that diffuse reflectance imaging can provide sufficient spatial sampling of the phantom for differentiation of 30 μm structural features of the embedded absorbing pattern inside the scattering media.

HANDBOOK: GROUNDWATER - METHODOLOGY - VOL. 2

EPA Science Inventory

The subsurface environment of ground water is characterized by a complex interplay of physical, geochemical and biological forces that govern the release, transport and fate of a variety of chemical substances. There are literally as many varied hydrogeologic settings as there ar...

New Interpretations of the Rayn Anticlines in the Arabian Basin Inferred from Gravity Modelling

NASA Astrophysics Data System (ADS)

AlMogren, S. M.; Mukhopadhyay, M.

2014-12-01

The Ryan Anticlines comprise of a regularly-spaced set of super-giant anticlines oriented NNW, developed due to E-W compression in the Arabian Basin. Most prominent of these being: the Ghawar Anticline, followed by the Summan, Khurais Anticlines and Qatar Arch. Gravity anomaly is largely characteristic for both Ryan Anticlines and its smaller size version the Jinadriah Anticline in the Riyadh Salt Basin. It displays a bipolar gravity field - a zone of gravity high running along the fold axis that is flanked by asymmetric gravity lows. Available structural models commonly infer structural uplift for the median gravity high but ignore the flanking lows. Here we interpret the bipolar gravity anomaly due primarily to such anticline structures, while, the flanking gravity lows are due to greater sediment thickness largely compacted and deformed over the basement depressions. Further complexities are created due to the salt layer and its migration at the lower horizons of sediment strata. Such diagnostic gravity anomaly pattern is taken here as an evidence for basement tectonics due to prevailing crustal dynamics in the Arabian Basin. Density inversion provides details on the subsurface density variation due to the folding and structural configuration for the sediment layers, including the salt layer, affected by basement deformation. This interpretation is largely supported by gravity forward and inversion models given in the present study what is partly constrained by the available seismic, MT and deep resistivity lines and surface geologic mapping. Most of the oil-gas fields in this part of the Arabian Basin are further known for salt diapirism. In this study the gravity interpretation help in identification of salt diapirism directly overlying the basement is firstly given here for Jinadriah Anticline; that is next extended to a regional geologic cross-section traversing the Ryan Anticlines to infer probable subsurface continuation of salt diapirs directly overlying the metamorphosed basement, sediment deformation pattern skirting the anticlines as well as their relationship of faulting to basement tectonics.

Tidal Fluctuations in a Deep Fault Extending Under the Santa Barbara Channel, California

NASA Astrophysics Data System (ADS)

Garven, G.; Stone, J.; Boles, J. R.

2013-12-01

Faults are known to strongly affect deep groundwater flow, and exert a profound control on petroleum accumulation, migration, and natural seafloor seepage from coastal reservoirs within the young sedimentary basins of southern California. In this paper we focus on major fault structure permeability and compressibility in the Santa Barbara Basin, where unique submarine and subsurface instrumentation provide the hydraulic characterization of faults in a structurally complex system. Subsurface geologic logs, geophysical logs, fluid P-T-X data, seafloor seep discharge patterns, fault mineralization petrology, isotopic data, fluid inclusions, and structural models help characterize the hydrogeological nature of faults in this seismically-active and young geologic terrain. Unique submarine gas flow data from a natural submarine seep area of the Santa Barbara Channel help constrain fault permeability k ~ 30 millidarcys for large-scale upward migration of methane-bearing formation fluids along one of the major fault zones. At another offshore site near Platform Holly, pressure-transducer time-series data from a 1.5 km deep exploration well in the South Ellwood Field demonstrate a strong ocean tidal component, due to vertical fault connectivity to the seafloor. Analytical models from classic hydrologic papers by Jacob-Ferris-Bredehoeft-van der Kamp-Wang can be used to extract large-scale fault permeability and compressibility parameters, based on tidal signal amplitude attenuation and phase shift at depth. For the South Ellwood Fault, we estimate k ~ 38 millidarcys (hydraulic conductivity K~ 3.6E-07 m/s) and specific storage coefficient Ss ~ 5.5E-08 m-1. The tidal-derived hydraulic properties also suggest a low effective porosity for the fault zone, n ~ 1 to 3%. Results of forward modeling with 2-D finite element models illustrate significant lateral propagation of the tidal signal into highly-permeable Monterey Formation. The results have important practical implications for fault characterization, petroleum migration, structural diagenesis, and carbon sequestration.

Depth Distribution and Assembly of Sulfate-Reducing Microbial Communities in Marine Sediments of Aarhus Bay

PubMed Central

Jochum, Lara M.; Chen, Xihan; Lever, Mark A.; Loy, Alexander; Jørgensen, Bo Barker; Schramm, Andreas

2017-01-01

ABSTRACT Most sulfate-reducing microorganisms (SRMs) present in subsurface marine sediments belong to uncultured groups only distantly related to known SRMs, and it remains unclear how changing geochemical zones and sediment depth influence their community structure. We mapped the community composition and abundance of SRMs by amplicon sequencing and quantifying the dsrB gene, which encodes dissimilatory sulfite reductase subunit beta, in sediment samples covering different vertical geochemical zones ranging from the surface sediment to the deep sulfate-depleted subsurface at four locations in Aarhus Bay, Denmark. SRMs were present in all geochemical zones, including sulfate-depleted methanogenic sediment. The biggest shift in SRM community composition and abundance occurred across the transition from bioturbated surface sediments to nonbioturbated sediments below, where redox fluctuations and the input of fresh organic matter due to macrofaunal activity are absent. SRM abundance correlated with sulfate reduction rates determined for the same sediments. Sulfate availability showed a weaker correlation with SRM abundances and no significant correlation with the composition of the SRM community. The overall SRM species diversity decreased with depth, yet we identified a subset of highly abundant community members that persists across all vertical geochemical zones of all stations. We conclude that subsurface SRM communities assemble by the persistence of members of the surface community and that the transition from the bioturbated surface sediment to the unmixed sediment below is a main site of assembly of the subsurface SRM community. IMPORTANCE Sulfate-reducing microorganisms (SRMs) are key players in the marine carbon and sulfur cycles, especially in coastal sediments, yet little is understood about the environmental factors controlling their depth distribution. Our results suggest that macrofaunal activity is a key driver of SRM abundance and community structure in marine sediments and that a small subset of SRM species of high relative abundance in the subsurface SRM community persists from the sulfate-rich surface sediment to sulfate-depleted methanogenic subsurface sediment. More generally, we conclude that SRM communities inhabiting the subsurface seabed assemble by the selective survival of members of the surface community. PMID:28939599

Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

NASA Technical Reports Server (NTRS)

Green, James L.; Markus, Thursten; Fung, Shing F.; Benson, Robert F.; Reinich, Bodo W.; Song, Paul; Gogineni, S. Prasad; Cooper, John F.; Taylor, William W. L.; Garcia, Leonard

2004-01-01

Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of 7 km on 1) an ocean and 2) a layer of bedrock. Knowledge of the ionospheric contributions to the time delay of the low-frequency subsurface radar is shown to be important in obtaining accurate depth information.

Interpreting Radar View near Mars' North Pole, Orbit 1512

NASA Technical Reports Server (NTRS)

2006-01-01

A radargram from the Shallow Subsurface Radar instrument (SHARAD) on NASA's Mars Reconnaissance Orbiter is shown in the upper-right panel and reveals detailed structure in the polar layered deposits of the north pole of Mars (with blowups shown in the upper-left panels). The sounding radar collected the data presented here during orbit 1512 of the mission, on Nov. 22, 2006.

The horizontal scale in the radargram is distance along the ground track. It can be referenced to the ground track map shown in the lower right. The radar traversed from about 83.5 degrees to 80.5 degrees north latitude, or about 180 kilometers (110 miles). The ground track map shows elevation measured by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. Green indicates low elevation; reddish-white indicates higher elevation. The traverse is from the high elevation of the plateau formed by the layers to the lowlands below.

The vertical scale on the radargram is time delay of the radar signals reflected back to Mars Reconnaissance Orbiter from the surface and subsurface. For reference, using an assumed velocity of the radar waves in the subsurface, time is converted to depth below the surface in two places: about 600 meters (2,000 feet) to the lowest of an upper series of bright reflectors and about 2,000 meters (6,500 feet) to the base of the polar layered deposits. The color scale of the radargram varies from black for weak reflections to bright yellow for strong reflections.

The lower-left panel is a image from the Mars Orbiter Camera on Mars Global Surveyor showing exposed polar layering in the walls of a canyon near the north pole. The layering is divided into a finely structured upper unit (labeled 'Upper PLD') and less-well-defined stratigraphy in the lower unit (labeled 'Lower PLD'). The radargram clearly reveals the complexity of the layering in the upper unit, additional reflections from the lower unit, and the base of the entire stack of layered deposits. The layering manifests the recent climate history of Mars, recorded by the deposition and removal of ice and dust.

The Shallow Subsurface Radar was provided by the Italian Space Agency (ASI). Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science team. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington.

Intermediate Scale Experimental Design to Validate a Subsurface Inverse Theory Applicable to Date-sparse Conditions

NASA Astrophysics Data System (ADS)

Jiao, J.; Trautz, A.; Zhang, Y.; Illangasekera, T.

2017-12-01

Subsurface flow and transport characterization under data-sparse condition is addressed by a new and computationally efficient inverse theory that simultaneously estimates parameters, state variables, and boundary conditions. Uncertainty in static data can be accounted for while parameter structure can be complex due to process uncertainty. The approach has been successfully extended to inverting transient and unsaturated flows as well as contaminant source identification under unknown initial and boundary conditions. In one example, by sampling numerical experiments simulating two-dimensional steady-state flow in which tracer migrates, a sequential inversion scheme first estimates the flow field and permeability structure before the evolution of tracer plume and dispersivities are jointly estimated. Compared to traditional inversion techniques, the theory does not use forward simulations to assess model-data misfits, thus the knowledge of the difficult-to-determine site boundary condition is not required. To test the general applicability of the theory, data generated during high-precision intermediate-scale experiments (i.e., a scale intermediary to the field and column scales) in large synthetic aquifers can be used. The design of such experiments is not trivial as laboratory conditions have to be selected to mimic natural systems in order to provide useful data, thus requiring a variety of sensors and data collection strategies. This paper presents the design of such an experiment in a synthetic, multi-layered aquifer with dimensions of 242.7 x 119.3 x 7.7 cm3. Different experimental scenarios that will generate data to validate the theory are presented.

Effect of bacteria and dissolved organics on mineral dissolution kinetics:

NASA Astrophysics Data System (ADS)

Pokrovsky, Oleg; Shirokova, Liudmila; Benezeth, Pascale; Zabelina, Svetlana

2010-05-01

Quantification of the effect of microorganisms and associated organic ligands on mineral dissolution rate is one among the last remaining challenges in modeling of water-rock interactions under earth surface and subsurface environments. This is especially true for deep underground settings within the context of CO2 capture, sequestration and storage. First, elevated CO2 pressures create numerous experimental difficulties for performing robust flow-through experiments at a given saturation state. Second, reactivity of main rock-forming minerals in abiotic systems at pCO2 >> 1 atm and circumneutral pH is still poorly constrained. And third, most of microbial habitats of the subsurface biosphere are not suitable for routine culturing in the laboratory, many of them are anaerobic and even strictly anaerobic, and many bacteria and archae cultures can live only in the consortium of microorganisms which is very hard to maintain at a controlled and stable biomass concentration. For experimental modeling of bio-mineral interactions in the laboratory, two other main conceptual challenges exist. Typical concentration of dissolved organic carbon that serves as a main nutrient for heterotrophic bacteria in underground waters rarely exceeds 3-5 mg/L. Typical concentration of DOC in nutrient media used for bacteria culturing is between 100 and 10,000 mg/L. Therefore, performing mineral-bacteria interactions in the laboratory under environmentally-sound conditions requires significant dilution of the nutrient media or the use of flow-through reactors. Concerning the effect of organic ligands and bacterial excudates on rock-forming mineral dissolution, at the present time, mostly empirical (phenomenological) approach can be used. Indeed, the pioneering studies of Stumm and co-workers have established a firm basis for modeling the catalyzing and inhibiting effects of ligands on metal oxide dissolution rate. This approach, very efficient for studying the interaction of organic and inorganic ligands with trivalent metal oxides, is based on applying multiple spectroscopic techniques allowing to reveal the chemical structure of adsorbed complexes. However, due to i) low surface area of most rock-forming minerals (carbonates, non-clay silicates), ii) difficulties of applying surface spectroscopic techniques at elevated pressures, and iii) very complex nature of bacterial exometabolites, it is not possible at the present time, to use rigorous surface complexation approach for rationalizing ligand- and bacteria-affected mineral dissolution under sub-surface CO2 storage environment. In this work, we present examples of overcoming these difficulties via concerted study of olivine, wollastonite and calcite interaction with heterotrophic bacteria and methanogenic archaes.

Identifying Hydrologic Flowpaths on Arctic Hillslopes Using Electrical Resistivity and Self Potential

NASA Astrophysics Data System (ADS)

Voytek, E.; Rushlow, C. R.; Godsey, S.; Singha, K.

2015-12-01

Shallow subsurface flow is a dominant process controlling hillslope runoff generation, soil development, and solute reaction and transport. Despite their importance, the location and geometry of flowpaths are difficult to determine. In arctic environments, shallow subsurface flowpaths are limited to a thin zone of seasonal thaw above continuous permafrost, which is traditionally assumed to mimic to surface topography. Here we use a combined approach of electrical resistivity imaging (ERI) and self-potential measurements (SP) to map shallow subsurface flowpaths in and around water tracks, drainage features common to arctic hillslopes. ERI measurements delineate thawed zones in the subsurface that control flowpaths, while SP is sensitive to groundwater flow. We find that areas of low electrical resistivity in the water tracks are deeper than manual thaw depth estimates and variations from surface topography. This finding suggests that traditional techniques significantly underestimate active layer thaw and the extent of the flowpath network on arctic hillslopes. SP measurements identify complex 3-D flowpaths in the thawed zone. Our results lay the groundwork for investigations into the seasonal dynamics, hydrologic connectivity, and climate sensitivity of spatially distributed flowpath networks on arctic hillslopes.

Structural and tectonic setting of the Charleston, South Carolina, region: Evidence from the Tertiary stratigraphic record

USGS Publications Warehouse

Weems, R.E.; Lewis, W.C.

2002-01-01

Eleven upper Eocene through Pliocene stratigraphic units occur in the subsurface of the region surrounding Charleston, South Carolina. These units contain a wealth of information concerning the long-term tectonic and structural setting of that area. These stratigraphic units have a mosaic pattern of distribution, rather than a simple layered pattern, because deposition, erosion, and tectonic warping have interacted in a complex manner through time. By generating separate structure-contour maps for the base of each stratigraphic unit, an estimate of the original basal surface of each unit can be reconstructed over wide areas. Changes in sea level over geologic time generate patterns of deposition and erosion that are geographically unique for the time of each transgression. Such patterns fail to persist when compared sequentially over time. In some areas, however, there has been persistent, repetitive net downward of upward movement over the past 34 m.y. These repetitive patterns of persistent motion are most readily attributable to tectonism. The spatial pattern of these high and low areas is complex, but it appears to correlate well with known tectonic features of the region. This correlation suggests that the tectonic setting of the Charleston region is controlled by scissors-like compression on a crustal block located between the north-trending Adams Run fault and the northwest-trending Charleston fault. Tectonism is localized in the Charleston region because it lies within a discrete hinge zone that accommodates structural movement between the Cape Fear arch and the Southeast Georgia embayment.

Characterizing Micro- and Macro-Scale Seismicity from Bayou Corne, Louisiana

NASA Astrophysics Data System (ADS)

Baig, A. M.; Urbancic, T.; Karimi, S.

2013-12-01

The initiation of felt seismicity in Bayou Corne, Louisiana, coupled with other phenomena detected by residents on the nearby housing development, prompted a call to install a broadband seismic network to monitor subsurface deformation. The initial deployment was in place to characterize the deformation contemporaneous with the formation of a sinkhole located in close proximity to a salt dome. Seismic events generated during this period followed a swarm-like behaviour with moment magnitudes culminating around Mw2.5. However, the seismic data recorded during this sequence suffer from poor signal to noise, onsets that are very difficult to pick, and the presence of a significant amount of energy arriving later in the waveforms. Efforts to understand the complexity in these waveforms are ongoing, and involve invoking the complexities inherent in recording in a highly attenuating swamp overlying a complex three-dimensional structure with the strong material property contrast of the salt dome. In order to understand the event character, as well as to locally lower the completeness threshold of the sequence, a downhole array of 15 Hz sensors was deployed in a newly drilled well around the salt dome. Although the deployment lasted a little over a month in duration, over 1000 events were detected down to moment magnitude -Mw3. Waveform quality tended to be excellent, with very distinct P and S wave arrivals observable across the array for most events. The highest magnitude events were seen as well on the surface network and allowed for the opportunity to observe the complexities introduced by the site effects, while overcoming the saturation effects on the higher-frequency downhole geophones. This hybrid downhole and surface array illustrates how a full picture of subsurface deformation is only made possible by combining the high-frequency downhole instrumentation to see the microseismicity complemented with a broadband array to accurately characterize the source parameters for the larger magnitude events. Our presentation is focused on investigating this deformation, characterizing the scaling behaviour and the other source processes by taking advantage of the wide-band afforded to us through the deployment.

Characterisation of the heterogeneity of karst using electrical geophysics - applications in SW China

NASA Astrophysics Data System (ADS)

Binley, A. M.; Cheng, Q.; Tao, M.; Chen, X.

2017-12-01

The southwest China karst region is one of the largest globally continuous karst areas. The great (structural, hydrological and geochemical) complexity of karstic environments and their rapidly evolving nature make them extremely vulnerable to natural and anthropogenic processes/activities. Characterising the location and properties of structures within the karst critical zone, and understanding how the landform is evolving is essential for the mitigation and adaption to locally- and globally-driven changes. Because of the specific nature of karst geology and geomorphology in the humid tropics and subtropics, spatial heterogeneity is high, evidenced by specific landforms features. Such heterogeneity leads to a high dynamic variability of hydrological processes in space and time, along with a complex exchange of surface water and groundwater. Investigating karst hydrogeological features is extremely challenging because of the three-dimensional nature of the system. Observations from boreholes can vary significantly over several metres, making conventional aquifer investigative methods limited. Geophysical methods have emerged as potentially powerful tools for hydrogeological investigations. Geophysical surveys can help to obtain more insight into the complex conduit networks and depth of weathering, both of which can provide quantitative information about the hydrological and hydrochemical dynamics of the system, in addition to providing a better understanding of how critical zone structures have been established and how the landscape is evolving. We present here results from recent geophysical field campaigns in SW China. We illustrate the effectiveness of electrical methods for mapping soil infil in epikarst and report results from field-based investigations along hillslope and valley transects. Our results reveal distinct zones of relatively high electrical conductivity to depths of tens of metres, which we attribute to localised increased fracture density. We discuss how such surveys can be used alongside other investigative techniques to help improve our understanding of the structure and function of this complex subsurface environment.

Synergistic Use of Spacecraft Telecom Links for Collection of Planetary Radar Science Data

NASA Astrophysics Data System (ADS)

Asmar, S.; Bell, D. J.; Chahat, N. E.; Decrossas, E.; Dobreva, T.; Duncan, C.; Ellliot, H.; Jin, C.; Lazio, J.; Miller, J.; Preston, R.

2017-12-01

On multiple solar system missions, radar instruments have been used to probe subsurface geomorphology and to infer chemical composition based on the dielectric signature derived from the reflected signal. Example spacecraft radar instruments are the 90 MHz CONSERT radar used to probe the interior of Comet 67P/Churyumov-Gerasimenko to a depth of 760m, the 20 MHz SHARAD instrument used to investigate Mars subsurface ice features from Mars orbit at depths of 300 to 3000 meters and the upcoming RIMFAX 150 MHz to 1200 MHz ground penetrating radar that will ride on the Mars 2020 rover investigating to a depth of 10m below the rover. In all of these applications, the radar frequency and signal structures were chosen to match science goals of desired depth of penetration and spatial resolution combined with the expected subsurface materials and structures below the surface. Recently, JPL investigators have proposed a new radar science paradigm, synergistic use of the telecom hardware and telecom links to collect bistatic or monostatic radar signatures. All JPL spacecraft employ telecom hardware that operates at UHF (400 MHz and 900 MHz), X-band (8 GHz) or Ka-band (32 GHz). Using existing open-loop record functions in these radios, the telecom hardware can be used to capture opportunistic radar signatures from telecom signals penetrating the surface and reflecting off of subsurface structures. This paper reports on telecom strategies, radar science applications and recent laboratory and field tests to demonstrate the effectiveness of telecom link based radar data collection.

Seismic reflection and structuring characterization of deep aquifer system in the Dakhla syncline (Cap Bon, North-Eastern Tunisia)

NASA Astrophysics Data System (ADS)

Bellali, Abir; Jarraya Horriche, Faten; Gabtni, Hakim; Bédir, Mourad

2018-04-01

The Dakhla syncline is located in the North-Eastern Tunisia. It is bounded by Abd El Rahmene anticline to the North-West, El Haouaria Graben to the North-East, Grombalia Graben to the South-West and the Mediterranean Sea to the East. The main aquifer reservoirs of Dakhla syncline are constituted by stacks of fluvial to deltaic Neogene sequences and carbonates. The interpretation of eight seismic reflection profiles, calibrated by wire line logging data of three oil wells, hydraulic wells and geologic field sections highlighted the impact of tectonics on the structuring geometry of aquifers and their distribution in elevated structures and subsurface depressions. Lithostratigraphic correlations and seismic profiles analysis through the syncline show that the principal aquifers are thickest within the central and northern part of the study area and thinnest to the southern part of the syncline. Seismic sections shows that the fracture/fault pattern in this syncline is mainly concentrated along corridors with a major direction of NW-SE and secondary directions of N-S, E-W and NE-SW with different release. This is proved by the complexity structure of Eastern Tunisia, resulted from the interaction between the African and Eurasiatic plates. Isochron maps of aquifers systems exhibited the structuring of this syncline in sub-surface characterized by important lateral and vertical geometric and thickness variations. Seismic sections L1, L2, L3, L4, L5 and petroleum wells showed an heterogeneous multilayer aquifers of Miocene formed by the arrangement of ten sandstone bodies, separated by impermeable clay packages. Oligo-Miocene deposits correspond to the most great potential aquifers, with respectively an average transmissivity estimated: Somaa aquifer 6.5 10-4 m2/s, Sandstone level aquifer 2.6 10-3 m2/s, Beglia aquifer 1.1 10-3 m2/s, Ain Ghrab aquifer 1.3 10-4 m2/s and Oligocene aquifer 2 10-3 m2/s. The interpretation of spatial variations of seismic units and the recognition of tectonic structures and their development may reveal some new insights for hydrogeological aspects.

Geoelectrical Monitoring for the characterisation of the near surface interflow in small alpine catchment areas during continuous rain

NASA Astrophysics Data System (ADS)

Ita, A.; Römer, A.; Markart, G.; Klebinder, K.; Bieber, G.; Kohl, B.

2009-04-01

In a pilot study the bandwidth of the near surface interflow and subsurface stormflow was investigated on a hill slope complex at the military training centre Lizum/Walchen (approx. 2000m above sea level) in Tyrol. High amounts of precipitation (about 250 mm) were applied within 2 days by use of a transportable spray irrigation installation. During the first day water from a creek was applied to the test site. On the following day the site was sprinkled with a salt tracer for an hour followed by creek water for the rest of the day. To characterise the runoff, different measurements techniques were used in the irrigation field. The subsurface runoff was registered in calibrated tanks. Changes in soil moisture were measured with buried TDR-waveguides - arranged in four profiles from 15 cm to 115 cm soil depth in maximum. In addition three geoelectrical profiles were measured. Two geoelectrical profiles were positioned orthogonal to the slope in the precipitation area, where one was reaching over the edge. The third profile was parallel to the slope overlapping with the second profile. Electrode distances were 0.25 cm and 0.50 cm respectively with 48 electrodes per profile. Geoelectrical measurements were done periodically before, during and after the rain simulation experiments. These have been carried out with the newly developed geoelectric instrument of the Geological survey of Austria, GEOMON4D. The advantage of the instrument is that it can measure a resistivity section at high speed and in an automated, meaning monitoring mode. Therefore, it is possible to register small and fast changes in the soil conductivity caused by a tracer. Summarising it can be said that the resistivity soundings give a detailed picture regarding the geological structure of the research area as well as explicit knowledge of how the near surface interflow spreads out in the subsurface. The geoelectric measurements deliver precise information about the behaviour of the salt tracer, its lateral and vertical extend and the flow velocity in the subsurface. For a more elaborate interpretation the results of the measurements were put together to achieve the best information of the interflow processes.

Radar Imaging of Europa's Subsurface Properties and Processes: The View from Earth

NASA Astrophysics Data System (ADS)

Blankenship, D. D.; Moore, W. B.; Young, D. A.; Peters, M. E.

2007-12-01

A primary objective of future Europa studies will be to characterize the distribution of shallow subsurface water as well as to identify any ice-ocean interface. Another objective will be to understand the formation of surface and subsurface features associated with interchange processes between any ocean and the surface. Achieving these objectives will require either direct or inferred knowledge of the position of any ice/water interfaces as well as any brine or layer pockets. We will review the hypothesized processes that control the thermal, compositional and structural (TCS) properties, and therefore the dielectric character, of the subsurface of Europa's icy shell. Our approach will be to extract the TCS properties for various subsurface processes thought to control the formation of major surface (e.g., ridges/bands, lenticulae, chaos, cratering...) and subsurface (e.g., rigid shell eutectics, diapirs, accretionary lenses ...) features on Europa. We will then assess the spectrum of analog processes and TCS properties represented by Earth's cryosphere including both Arctic and Antarctic ice sheets, ice shelves and valley glaciers. There are few complete analogs over the full TCS space but, because of the wide range of ice thickness, impurities and strain rates for Earth's cryosphere, there are many more analogs than many Earth and planetary researchers might imagine for significant portions of this space (e.g., bottom crevasses, marine ice shelf/subglacial lake accretion, surging polythermal glaciers...).Our ultimate objective is to use these Earth analog studies to define the radar imaging approach for Europa's subsurface that will be most useful for supporting/refuting the hypotheses for the formation of major surface/subsurface features as well as for "pure" exploration of Europa's icy shell and its interface with the underlying ocean.

WISDOM : an UHF GPR on the Exomars Mission

NASA Astrophysics Data System (ADS)

Corbel, C.; Hamram, S.; Ney, R.; Plettemeier, D.; Dolon, F.; Jeangeot, A.; Ciarletti, V.; Berthelier, J.

2006-12-01

This paper describes the main technical features of WISDOM (Water Ice and Subsurface Deposit Observations on Mars) Ground Penetrating Radar. This radar has been selected on the PASTEUR payload of the ESA ExoMars rover. The launch is scheduled in 2011. The main objective of this mission is to acquire and analyze samples of the shallow subsurface and search for traces of extinct or extant life. The WISDOM GPR aims at providing observations of the structure and layering of the upper layers of the subsurface in order to retrieve geological information that are of prime interest to select optimal sites to drill. It will also localize buried obstacles (rocks, boulders, ?)in the underground that will make the delicate drilling operations safer. WISDOM will operate in the UHF range from 500 MHz to 3 GHz and probe the first few meters of the subsurface with a high resolution (a few centimeters). The large bandwidth requirement (2.5 GHz) led us to select a gated step frequency technique for WISDOM. The Step Frequency technique is based on the analysis of the system in the frequency domain. The phase and amplitude of the reflected signal are measured at about 200 different frequencies effectively measuring the transfer function of the sub-surface between the transmitter and receiver antenna. The impulse response and eventually the distance of the reflecting structures can be obtained by performing an inverse Fourier transform of the measured transfer function. The broad band antennas have been designed in order to have a wide radiation pattern into the sub-surface and to avoid the direct coupling and allow co and cross polar measurements. To decrease the direct signal between the transmitter and the receiver or strong reflections from the surface, hardware range gating is implemented. The performances of the instrument operated in well characterized conditions will be presented

Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary.

PubMed

Grayver, Alexander V; Schnepf, Neesha R; Kuvshinov, Alexey V; Sabaka, Terence J; Manoj, Chandrasekharan; Olsen, Nils

2016-09-01

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. We use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals a ≈72-km-thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

THERMAL HETEROGENEITY, STREAM CHANNEL MORPHOLOGY, AND SALMONID ABUNDANCE IN NORTHEASTERN OREGON STREAMS

EPA Science Inventory

Heterogeneity in stream water temperatures created by local influx of cooler subsurface waters into geomorphically complex stream channels was associated with increased abundance of rainbow trout (Oncorhynchus mykiss) and chinook salmon (O. tshawytscha) in northeastern Oregon. Th...

Glass sample preparation and performance investigations

NASA Astrophysics Data System (ADS)

Johnson, R. Barry

1992-04-01

This final report details the work performed under this delivery order from April 1991 through April 1992. The currently available capabilities for integrated optical performance modeling at MSFC for large and complex systems such as AXAF were investigated. The Integrated Structural Modeling (ISM) program developed by Boeing for the U.S. Air Force was obtained and installed on two DECstations 5000 at MSFC. The structural, thermal and optical analysis programs available in ISM were evaluated. As part of the optomechanical engineering activities, technical support was provided in the design of support structure, mirror assembly, filter wheel assembly and material selection for the Solar X-ray Imager (SXI) program. As part of the fabrication activities, a large number of zerodur glass samples were prepared in different sizes and shapes for acid etching, coating and polishing experiments to characterize the subsurface damage and stresses produced by the grinding and polishing operations. Various optical components for AXAF video microscope and the x-ray test facility were also fabricated. A number of glass fabrication and test instruments such as a scatter plate interferometer, a gravity feed saw and some phenolic cutting blades were fabricated, integrated and tested.

Forward Modeling of Receiver Functions to Determine Crustal Structure of the Eastern Limb in TheBushveld Complex, South Africa

NASA Astrophysics Data System (ADS)

Loza, E.; Ramirez, C.; Nyblade, A.; Durrheim, R. J.; Raveloson, A.

2016-12-01

The Bushveld Igneous Complex contains the largest layered mafic intrusion on Earth, about the size of England, and has been exploited for metals such as platinum since the 1950s. Several igneous bodies within and around the complex have been dated from 2.06 Ga, possibly representing a single massive magmatic event. The Rustenburg Layered Suite of the Bushveld Igneous Complex intruded into the Transvaal sedimentary sequence, with associated volcanic rocks of the Rooiberg Group forming the roof and part of the floor. The purpose of this study is to determine whether the Rustenburg Layered Suite is a continuous bowl-shaped formation or if it is made up of two separate dipping sheets that crop out in the western and eastern limbs. If the intrusion is connected at depth, then the Moho (crust-mantle boundary) would most likely be depressed due to the weight of the 7-8km of mafic material injected into the crust. Seismic stations were installed in the eastern and northern Bushveld in 2015 to collect teleseismic data. The use of receiver functions derived from seismic data collected since 2015 has helped determine the subsurface crustal structure of the Bushveld. Receiver functions have been used to trace the contact between the high-density mafic lower zone and the low-density Transvaal sediments. The new data gathered show the Moho boundary at about 47 km, and a 5.0 Gaussian width shows a backswing consistent with a mafic-sedimentary boundary at 8km.

Influence of Si wafer thinning processes on (sub)surface defects

NASA Astrophysics Data System (ADS)

Inoue, Fumihiro; Jourdain, Anne; Peng, Lan; Phommahaxay, Alain; De Vos, Joeri; Rebibis, Kenneth June; Miller, Andy; Sleeckx, Erik; Beyne, Eric; Uedono, Akira

2017-05-01

Wafer-to-wafer three-dimensional (3D) integration with minimal Si thickness can produce interacting multiple devices with significantly scaled vertical interconnections. Realizing such a thin 3D structure, however, depends critically on the surface and subsurface of the remaining backside Si after the thinning processes. The Si (sub)surface after mechanical grinding has already been characterized fruitfully for a range of few dozen of μm. Here, we expand the characterization of Si (sub)surface to 5 μm thickness after thinning process on dielectric bonded wafers. The subsurface defects and damage layer were investigated after grinding, chemical mechanical polishing (CMP), wet etching and plasma dry etching. The (sub)surface defects were characterized using transmission microscopy, atomic force microscopy, and positron annihilation spectroscopy. Although grinding provides the fastest removal rate of Si, the surface roughness was not compatible with subsequent processing. Furthermore, mechanical damage such as dislocations and amorphous Si cannot be reduced regardless of Si thickness and thin wafer handling systems. The CMP after grinding showed excellent performance to remove this grinding damage, even though the removal amount is 1 μm. For the case of Si thinning towards 5 μm using grinding and CMP, the (sub)surface is atomic scale of roughness without vacancy. For the case of grinding + dry etch, vacancy defects were detected in subsurface around 0.5-2 μm. The finished surface after wet etch remains in the nm scale in the strain region. By inserting a CMP step in between grinding and dry etch it is possible to significantly reduce not only the roughness, but also the remaining vacancies at the subsurface. The surface of grinding + CMP + dry etching gives an equivalent mono vacancy result as to that of grinding + CMP. This combination of thinning processes allows development of extremely thin 3D integration devices with minimal roughness and vacancy surface.

High-resolution airborne gravity imaging over James Ross Island (West Antarctica)

USGS Publications Warehouse

Jordan, T.A.; Ferraccioli, F.; Jones, P.C.; Smellie, J.L.; Ghidella, M.; Corr, H. F. J.; Zakrajsek, A.F.

2007-01-01

James Ross Island (JRI) exposes a Miocene-Recent alkaline basaltic volcanic complex that developed in a back-arc, east of the northern Antarctic Peninsula. JRI has been the focus of several geological studies because it provides a window on Neogene magmatic processes and paleoenvironments. However, little is known about its internal structure. New airborne gravity data were collected as part of the first high-resolution aerogeophysical survey flown over the island and reveal a prominent negative Bouguer gravity anomaly over Mt Haddington. This is intriguing as basaltic volcanoes are typically associated with positive Bouguer anomalies, linked to underlying mafic intrusions. The negative Bouguer anomaly may be associated with a hitherto unrecognised low-density sub-surface body, such as a breccia-filled caldera, or a partially molten magma chamber.

Extrapolating surface structures to depth in transpressional systems: the role of rheology and convergence angle deduced from analogue experiments

NASA Astrophysics Data System (ADS)

Hsieh, Shang Yu; Neubauer, Franz; Cloetingh, Sierd; Willingshofer, Ernst; Sokoutis, Dimitrios

2014-05-01

The internal structure of major strike-slip faults is still poorly understood, particularly how the deep structure could be inferred from its surface expression (Molnar and Dayem, 2011 and references therein). Previous analogue experiments suggest that the convergence angle is the most influential factor (Leever et al., 2011). Further analogue modeling may allow a better understanding how to extrapolate surface structures to the subsurface geometry of strike-slip faults. Various scenarios of analogue experiments were designed to represent strike-slip faults in nature from different geological settings. As such key parameters, which are investigated in this study include: (a) the angle of convergence, (b) the thickness of brittle layer, (c) the influence of a rheological weak layer within the crust, and (d) influence of a thick and rheologically weak layer at the base of the crust. The latter aimed to simulate the effect of a hot metamorphic core complex or an alignment of uprising plutons bordered by a transtensional/transpressional strike-slip fault. The experiments are aimed to explain first order structures along major transcurrent strike-slip faults such as the Altyn, Kunlun, San Andrea and Greendale (Darfield earthquake 2010) faults. The preliminary results show that convergence angle significantly influences the overall geometry of the transpressive system with greater convergence angles resulting in wider fault zones and higher elevation. Different positions, densities and viscosities of weak rheological layers have not only different surface expressions but also affect the fault geometry in the subsurface. For instance, rheological weak material in the bottom layer results in stretching when experiment reaches a certain displacement and a buildup of a less segmented, wide positive flower structure. At the surface, a wide fault valley in the middle of the fault zone is the reflection of stretching along the velocity discontinuity at depth. In models with a thin and rheologically weaker layer in the middle of the brittle layer, deformation is distributed over more faults and the geometry of the fault zone below and above the weak zone shows significant differences, suggesting that the correlation of structures across a weak layer has to be supported by geophysical data, which help constraining the geometry of the deep part. This latter experiment has significantly similar phenomena in reality, such as few pressure ridges along Altyn fault. The experimental results underline the need to understand the role of the convergence angle and the influence of rheology on fault evolution, in order to connect between surface deformation and subsurface geometry. References Leever, K. A., Gabrielsen, R. H., Sokoutis, D., Willingshofer, E., 2011. The effect of convergence angle on the kinematic evolution of strain partitioning in transpressional brittle wedges: Insight from analog modeling and high-resolution digital image analysis. Tectonics, 30(2), TC2013. Molnar, P., Dayem, K.E., 2010. Major intracontinental strike-slip faults and contrasts in lithospheric strength. Geosphere, 6, 444-467.

A comparison between modeled and measured permafrost temperatures at Ritigraben borehole, Switzerland

NASA Astrophysics Data System (ADS)

Mitterer-Hoinkes, Susanna; Lehning, Michael; Phillips, Marcia; Sailer, Rudolf

2013-04-01

The area-wide distribution of permafrost is sparsely known in mountainous terrain (e.g. Alps). Permafrost monitoring can only be based on point or small scale measurements such as boreholes, active rock glaciers, BTS measurements or geophysical measurements. To get a better understanding of permafrost distribution, it is necessary to focus on modeling permafrost temperatures and permafrost distribution patterns. A lot of effort on these topics has been already expended using different kinds of models. In this study, the evolution of subsurface temperatures over successive years has been modeled at the location Ritigraben borehole (Mattertal, Switzerland) by using the one-dimensional snow cover model SNOWPACK. The model needs meteorological input and in our case information on subsurface properties. We used meteorological input variables of the automatic weather station Ritigraben (2630 m) in combination with the automatic weather station Saas Seetal (2480 m). Meteorological data between 2006 and 2011 on an hourly basis were used to drive the model. As former studies showed, the snow amount and the snow cover duration have a great influence on the thermal regime. Low snow heights allow for deeper penetration of low winter temperatures into the ground, strong winters with a high amount of snow attenuate this effect. In addition, variations in subsurface conditions highly influence the temperature regime. Therefore, we conducted sensitivity runs by defining a series of different subsurface properties. The modeled subsurface temperature profiles of Ritigraben were then compared to the measured temperatures in the Ritigraben borehole. This allows a validation of the influence of subsurface properties on the temperature regime. As expected, the influence of the snow cover is stronger than the influence of sub-surface material properties, which are significant, however. The validation presented here serves to prepare a larger spatial simulation with the complex hydro-meteorological 3-dimensional model Alpine 3D, which is based on a distributed application of SNOWPACK.

Concentration and characterization of dissolved organic matter in the surface microlayer and subsurface water of the Bohai Sea, China

NASA Astrophysics Data System (ADS)

Chen, Yan; Yang, Gui-Peng; Wu, Guan-Wei; Gao, Xian-Chi; Xia, Qing-Yan

2013-01-01

A total of 19 sea-surface microlayer and corresponding subsurface samples collected from the Bohai Sea, China in April 2010 were analyzed for chlorophyll a, dissolved organic carbon (DOC) and its major compound classes including total dissolved carbohydrates (TDCHO, including monosaccharides, MCHO, and polysaccharides, PCHO) and total hydrolysable amino acids (THAA, including dissolved free, DFAA, and combined fraction, DCAA). The concentrations of DOC in the subsurface water ranged from 130.2 to 407.7 μM C, with an average of 225.9±75.4 μM C, while those in the surface microlayer varied between 140.1 and 330.9 μM C, with an average of 217.8±56.8 μM C. The concentrations of chlorophyll a, DOC, TDCHO and THAA in the microlayer were, respectively correlated with their subsurface water concentrations, implying that there was a strong exchange effect between the microlayer and subsurface water. The concentrations of DOC and TDCHO were negatively correlated with salinity, respectively, indicating that water mixing might play an important role in controlling the distribution of DOC and TDCHO in the water column. Major constituents of DCAA and DFAA present in the study area were glycine, alanine, glutamic acid, serine and histidine. Principal component analysis (PCA) was applied to examine the complex compositional differences that existed among the sampling sites. Our results showed that DFAA had higher mole percentages of glycine, valine and serine in the microlayer than in the subsurface water, while DCAA tended to have higher mole percentages of glutamic acid, aspartic acid, threonine, arginine, alanine, tyrosine, phenylalanine and leucine in the microlayer. The yields of TDCHO and THAA exhibited similar trends between the microlayer and subsurface water. Carbohydrate species displayed significant enrichment in the microlayer, whereas the DFAA and DCAA exhibited non-uniform enrichment in the microlayer.

Understanding the rapidity of subsurface storm flow response from a fracture-oriented shallow vadose through a new perspective

NASA Astrophysics Data System (ADS)

Zhao, Peng; Zhao, Pei; Liang, Chuan; Li, Tianyang; Zhou, Baojia

2017-01-01

Velocity and celerity in hydrologic systems are controlled by different mechanisms. Efforts were made through joint sample collection and the use of hydrographs and tracers to understand the rapidity of the subsurface flow response to rainstorms on hourly time scales. Three deep subsurface flows during four natural rainstorm events were monitored. The results show that (1) deeper discharge was observed early in responding rainfall events and yielded a high hydrograph amplitude; (2) a ratio index, k, reflecting the dynamic change of the rainfall perturbation intensity in subsurface flow, might reveal inner causal relationships between the flow index and the tracer signal index. Most values of k were larger than 1 at the perturbation stage but approximated 1 at the no-perturbation stage; and (3) for statistical analysis of tracer signals in subsurface flows, the total standard deviation was 17.2, 11.9, 7.4 and 3.5 at perturbation stages and 4.4, 2.5, 1.1, and 0.95 at the non-perturbation stage for observed events. These events were 3-7 times higher in the former rather than the later, reflecting that the variation of tracer signals primarily occurred under rainfall perturbation. Thus, we affirmed that the dynamic features of rainfall have a key effect on rapid processes because, besides the gravity, mechanical waves originating from dynamic rainfall features are another driving factor for conversion between different types of rainfall mechanical energy. A conceptual model for pressure wave propagation was proposed, in which virtual subsurface flow processes in a heterogeneous vadose zone under rainfall are analogous to the water hammer phenomenon in complex conduit systems. Such an analogy can allow pressure in a shallow vadose to increase and decrease and directly influence the velocity and celerity of the flow reflecting a mechanism for rapid subsurface hydrologic response processes in the shallow vadose zone.

Integration of multi-source and multi-scale datasets for 3D structural modeling for subsurface exploration targeting, Luanchuan Mo-polymetallic district, China

NASA Astrophysics Data System (ADS)

Wang, Gongwen; Ma, Zhenbo; Li, Ruixi; Song, Yaowu; Qu, Jianan; Zhang, Shouting; Yan, Changhai; Han, Jiangwei

2017-04-01

In this paper, multi-source (geophysical, geochemical, geological and remote sensing) datasets were used to construct multi-scale (district-, deposit-, and orebody-scale) 3D geological models and extract 3D exploration criteria for subsurface Mo-polymetallic exploration targeting in the Luanchuan district in China. The results indicate that (i) a series of region-/district-scale NW-trending thrusts controlled main Mo-polymetallic forming, and they were formed by regional Indosinian Qinling orogenic events, the secondary NW-trending district-scale folds and NE-trending faults and the intrusive stock structure are produced based on thrust structure in Caledonian-Indosinian orogenic events; they are ore-bearing zones and ore-forming structures; (ii) the NW-trending district-scale and NE-trending deposit-scale normal faults were crossed and controlled by the Jurassic granite stocks in 3D space, they are associated with the magma-skarn Mo polymetallic mineralization (the 3D buffer distance of ore-forming granite stocks is 600 m) and the NW-trending hydrothermal Pb-Zn deposits which are surrounded by the Jurassic granite stocks and constrained by NW-trending or NE-trending faults (the 3D buffer distance of ore-forming fault is 700 m); and (iii) nine Mo polymetallic and four Pb-Zn targets were identified in the subsurface of the Luanchuan district.

Lunar regolith stratigraphy analysis based on the simulation of lunar penetrating radar signals

NASA Astrophysics Data System (ADS)

Lai, Jialong; Xu, Yi; Zhang, Xiaoping; Tang, Zesheng

2017-11-01

The thickness of lunar regolith is an important index of evaluating the quantity of lunar resources such as 3He and relative geologic ages. Lunar penetrating radar (LPR) experiment of Chang'E-3 mission provided an opportunity of in situ lunar subsurface structure measurement in the northern mare imbrium area. However, prior work on analyzing LPR data obtained quite different conclusions of lunar regolith structure mainly because of the missing of clear interface reflectors in radar image. In this paper, we utilized finite-difference time-domain (FDTD) method and three models of regolith structures with different rock density, number of layers, shapes of interfaces, and etc. to simulate the LPR signals for the interpretation of radar image. The simulation results demonstrate that the scattering signals caused by numerous buried rocks in the regolith can mask the horizontal reflectors, and the die-out of radar echo does not indicate the bottom of lunar regolith layer and data processing such as migration method could recover some of the subsurface information but also result in fake signals. Based on analysis of simulation results, we conclude that LPR results uncover the subsurface layered structure containing the rework zone with multiple ejecta blankets of small crater, the ejecta blanket of Chang'E-3 crater, and the transition zone and estimate the thickness of the detected layer is about 3.25 m.

Using lagged dependence to identify (de)coupled surface and subsurface soil moisture values

NASA Astrophysics Data System (ADS)

Carranza, Coleen D. U.; van der Ploeg, Martine J.; Torfs, Paul J. J. F.

2018-04-01

Recent advances in radar remote sensing popularized the mapping of surface soil moisture at different spatial scales. Surface soil moisture measurements are used in combination with hydrological models to determine subsurface soil moisture values. However, variability of soil moisture across the soil column is important for estimating depth-integrated values, as decoupling between surface and subsurface can occur. In this study, we employ new methods to investigate the occurrence of (de)coupling between surface and subsurface soil moisture. Using time series datasets, lagged dependence was incorporated in assessing (de)coupling with the idea that surface soil moisture conditions will be reflected at the subsurface after a certain delay. The main approach involves the application of a distributed-lag nonlinear model (DLNM) to simultaneously represent both the functional relation and the lag structure in the time series. The results of an exploratory analysis using residuals from a fitted loess function serve as a posteriori information to determine (de)coupled values. Both methods allow for a range of (de)coupled soil moisture values to be quantified. Results provide new insights into the decoupled range as its occurrence among the sites investigated is not limited to dry conditions.

Effects of subsurface aeration and trinexapac-ethyl application on soil microbial communities in a creeping bentgrass putting green

USGS Publications Warehouse

Feng, Y.; Stoeckel, D.M.; Van Santen, E.; Walker, R.H.

2002-01-01

The sensitivity of creeping bentgrass (Agrostis palustris Huds.) to the extreme heat found in the southeastern United States has led to the development of new greens-management methods. The purpose of this study was to examine the effects of subsurface aeration and growth regulator applications on soil microbial communities and mycorrhizal colonization rates in a creeping bentgrass putting green. Two cultivars (Crenshaw and Penncross), a growth regulator (trinexapacethyl), and subsurface aeration were evaluated in cool and warm seasons. Total bacterial counts were higher in whole (unsieved) soils than in sieved soils, indicating a richer rhizosphere soil environment. Mycorrhizal infection rates were higher in trinexapac-ethyl (TE) treated plants. High levels of hyphal colonization and relatively low arbuscule and vesicle occurrence were observed. Principal components analysis of whole-soil fatty acid methyl ester (FAME) profiles indicated that warm-season microbial populations in whole and sieved soils had similar constituents, but the populations differed in the cool season. FAME profiles did not indicate that subsurface aeration and TE application affected soil microbial community structure. This is the first reported study investigating the influences of subsurface aeration and TE application on soil microorganisms in a turfgrass putting green soil.

A multi-scale experimental and simulation approach for fractured subsurface systems

NASA Astrophysics Data System (ADS)

Viswanathan, H. S.; Carey, J. W.; Frash, L.; Karra, S.; Hyman, J.; Kang, Q.; Rougier, E.; Srinivasan, G.

2017-12-01

Fractured systems play an important role in numerous subsurface applications including hydraulic fracturing, carbon sequestration, geothermal energy and underground nuclear test detection. Fractures that range in scale from microns to meters and their structure control the behavior of these systems which provide over 85% of our energy and 50% of US drinking water. Determining the key mechanisms in subsurface fractured systems has been impeded due to the lack of sophisticated experimental methods to measure fracture aperture and connectivity, multiphase permeability, and chemical exchange capacities at the high temperature, pressure, and stresses present in the subsurface. In this study, we developed and use microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. In addition we have developed high fidelity fracture propagation and discrete fracture network flow models to simulate these fractured systems. We also have developed reduced order models of these fracture simulators in order to conduct uncertainty quantification for these systems. We demonstrate an integrated experimental/modeling approach that allows for a comprehensive characterization of fractured systems and develop models that can be used to optimize the reservoir operating conditions over a range of subsurface conditions.

Results from Field Testing the RIMFAX GPR on Svalbard.

NASA Astrophysics Data System (ADS)

Hamran, S. E.; Amundsen, H. E. F.; Berger, T.; Carter, L. M.; Dypvik, H.; Ghent, R. R.; Kohler, J.; Mellon, M. T.; Nunes, D. C.; Paige, D. A.; Plettemeier, D.; Russell, P.

2017-12-01

The Radar Imager for Mars' Subsurface Experiment - RIMFAX is a Ground Penetrating Radar being developed for NASÁs MARS 2020 rover mission. The principal goals of the RIMFAX investigation are to image subsurface structures, provide context for sample sites, derive information regarding subsurface composition, and search for ice or brines. In meeting these goals, RIMFAX will provide a view of the stratigraphic section and a window into the geological and environmental history of Mars. To verify the design an Engineering Model (EM) of the radar was tested in the field in the spring 2017. Different sounding modes on the EM were tested in different types of subsurface geology on Svalbard. Deep soundings were performed on polythermal glaciers down to a couple of hundred meters. Shallow soundings were used to map a ground water table in the firn area of a glacier. A combination of deep and shallow soundings was used to image buried ice under a sedimentary layer of a couple of meters. Subsurface sedimentary layers were imaged down to more than 20 meters in sand stone permafrost. This presentation will give an overview of the RIMFAX investigation, describe the development of the radar system, and show results from field tests of the radar.

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processes receives subsurface states frommore » PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of changes subsurface electrical conductivity, in both the saturated and unsaturated zones, arising from water table changes and from river water intrusion into the aquifer. The results also demonstrate the sensitivity of surface based ERT measurements to those changes over time. PFLOTRAN-E4D is available with the PFLOTRAN development version with an open-source license at https://bitbucket.org/pflotran/pflotran-dev .« less

PFLOTRAN-E4D: A parallel open source PFLOTRAN module for simulating time-lapse electrical resistivity data

NASA Astrophysics Data System (ADS)

Johnson, Timothy C.; Hammond, Glenn E.; Chen, Xingyuan

2017-02-01

Time-lapse electrical resistivity tomography (ERT) is finding increased application for remotely monitoring processes occurring in the near subsurface in three-dimensions (i.e. 4D monitoring). However, there are few codes capable of simulating the evolution of subsurface resistivity and corresponding tomographic measurements arising from a particular process, particularly in parallel and with an open source license. Herein we describe and demonstrate an electrical resistivity tomography module for the PFLOTRAN subsurface flow and reactive transport simulation code, named PFLOTRAN-E4D. The PFLOTRAN-E4D module operates in parallel using a dedicated set of compute cores in a master-slave configuration. At each time step, the master processes receives subsurface states from PFLOTRAN, converts those states to bulk electrical conductivity, and instructs the slave processes to simulate a tomographic data set. The resulting multi-physics simulation capability enables accurate feasibility studies for ERT imaging, the identification of the ERT signatures that are unique to a given process, and facilitates the joint inversion of ERT data with hydrogeological data for subsurface characterization. PFLOTRAN-E4D is demonstrated herein using a field study of stage-driven groundwater/river water interaction ERT monitoring along the Columbia River, Washington, USA. Results demonstrate the complex nature of subsurface electrical conductivity changes, in both the saturated and unsaturated zones, arising from river stage fluctuations and associated river water intrusion into the aquifer. The results also demonstrate the sensitivity of surface based ERT measurements to those changes over time. PFLOTRAN-E4D is available with the PFLOTRAN development version with an open-source license at https://bitbucket.org/pflotran/pflotran-dev.

A Review of distribution and quantity of lingering subsurface oil from the Exxon Valdez Oil Spill

NASA Astrophysics Data System (ADS)

Nixon, Zachary; Michel, Jacqueline

2018-01-01

Remaining lingering subsurface oil residues from the Exxon Valdez oil spill (EVOS) are, at present, patchily distributed across the geologically complex and spatially extensive shorelines of Prince William Sound and the Gulf of Alaska. We review and synthesize previous literature describing the causal geomorphic and physical mechanisms for persistence of oil in the intertidal subsurface sediments of these areas. We also summarize previous sampling and modeling efforts, and refine previously presented models with additional data to characterize the present-day linear and areal spatial extent, and quantity of lingering subsurface oil. In the weeks after the spill in March of 1989, approximately 17,750 t of oil were stranded along impacted shorelines, and by October of 1992, only 2% of the mass of spilled oil was estimated to remain in intertidal areas. We estimate that lingering subsurface residues, generally between 5 and 20 cm thick and sequestered below 10-20 cm of clean sediment, are present over 30 ha of intertidal area, along 11.4 km of shoreline, and represent approximately 227 t or 0.6% of the total mass of spilled oil. These residues are typically located in finer-grained sand and gravel sediments, often under an armor of cobble- or boulder-sized clasts, in areas with limited groundwater flow and porosity. Persistence of these residues is correlated with heavy initial oil loading together with localized sheltering from physical disturbance such as wave energy within the beach face. While no longer generally bioavailable and increasingly chemically weathered, present removal rates for these remaining subsurface oil residues have slowed to nearly zero. The only remaining plausible removal mechanisms will operate over time scales of decades.

Modeling of Near-Surface Leakage and Seepage of CO2 for Risk Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oldenburg, Curtis M.; Unger, Andre A.J.

2004-02-18

The injection of carbon dioxide (CO2) into deep geologic carbon sequestration sites entails risk that CO2 will leak away from the primary storage formation and migrate upwards to the unsaturated zone from which it can seep out of the ground. We have developed a coupled modeling framework called T2CA for simulating CO2 leakage and seepage in the subsurface and in the atmospheric surface layer. The results of model simulations can be used to calculate the two key health, safety, and environmental (HSE) risk drivers, namely CO2 seepage flux and nearsurface CO2 concentrations. Sensitivity studies for a subsurface system with amore » thick unsaturated zone show limited leakage attenuation resulting in correspondingly large CO2 concentrations in the shallow subsurface. Large CO2 concentrations in the shallow subsurface present a risk to plant and tree roots, and to humans and other animals in subsurface structures such as basements or utility vaults. Whereas CO2 concentrations in the subsurface can be high, surfacelayer winds reduce CO2 concentrations to low levels for the fluxes investigated. We recommend more verification and case studies be carried out with T2CA, along with the development of extensions to handle additional scenarios such as calm conditions, topographic effects, and catastrophic surface-layer discharge events.« less

Washington Geothermal Play Fairway Analysis Data From Potential Field Studies

DOE Data Explorer

Anderson, Megan; Ritzinger, Brent; Glen, Jonathan; Schermerhorn, William

2017-12-20

A recent study which adapts play fairway analysis (PFA) methodology to assess geothermal potential was conducted at three locations (Mount Baker, Mount St. Helens seismic zone, and Wind River valley) along the Washington Cascade Range (Forson et al. 2017). Potential field (gravity and magnetic) methods which can detect subsurface contrasts in physical properties, provides a means for mapping and modeling subsurface geology and structure. As part of the WA-Cascade PFA project, we performed potential field studies by collecting high-resolution gravity and ground-magnetic data, and rock property measurements to (1) identify and constrain fault geometries (2) constrain subsurface lithologic distribution (3) study fault interactions (4) identify areas favorable to hydrothermal flow, and ultimately (5) guide future geothermal exploration at each location.

Evaluation of subsurface damage in concrete deck joints using impact echo method

DOE PAGES

Rickard, Larry; Choi, Wonchang

2016-01-01

Many factors can affect the overall performance and longevity of highway bridges, including the integrity of their deck joints. This study focuses on the evaluation of subsurface damage in deteriorated concrete deck joints, which includes the delamination and corrosion of the reinforcement. Impact echo and surface wave technology, mainly a portable seismic property analyzer (PSPA), were employed to evaluate the structural deficiency of concrete joints. Laboratory tests of core samples were conducted to verify the nondestructive test results. As a result, the primary advantage of the PSPA as a bridge assessment tool lies in its ability to assess the concrete’smore » modulus and to detect subsurface defects at a particular point simultaneously.« less

Metabolic and Physiological Characteristics of Novel Cultivars from Serpentinite Seep Fluids

NASA Astrophysics Data System (ADS)

Nelson, B.; Chowdhury, S.; Brazelton, W. J.; Schrenk, M. O.

2011-12-01

Subsurface waters associated with the alteration of ultramafic rocks become highly reducing and alkaline through a process known as serpentinization. As habitat, these fluids are in many ways metabolically constraining but can provide sufficient energy for chemolithotrophy. As part of an ongoing effort to characterize these communities, heterotrophic enrichment cultures and anaerobic microcosms were initiated with alkaline waters found at three geographically and geochemically distinct sites of active serpentinization. These include the Northern Apennine ophiolite in the Ligurian region of Italy, the Tablelands ophiolite at Gros Morne National Park, Canada and the Coast Range ophiolite at McLaughlin Natural Reserve, California. Enrichment cultures at pH 11 yielded numerous isolates related to Proteobacteria and Firmicutes, some of which are closely related to other cultivars from high pH and subsurface environments. Anaerobic water samples were amended with combinations of electron donors (hydrogen, complex organics, acetate) and acceptors (ferric iron, sulfate) in a block design. After several weeks of incubation, DNA was extracted from cell concentrations and community differences were compared by TRFLP. Of particular interest is the isolation of a putative iron reducing Firmicute from samples enriched with complex organic compounds and ferric citrate. Ongoing studies are aimed at characterizing the physiology of these isolates. These data provide important insights into the metabolic potential of serpentinite subsurface ecosystems, and are a complement to culture-independent genomic analyses.

A Method for Partitioning Surface and Subsurface Flow Using Rainfall Simulaton and Two-Dimensional Surface Electrical Resistivity Imaging

NASA Astrophysics Data System (ADS)

Carey, A. M.; Paige, G. B.; Miller, S. N.; Carr, B. J.; Holbrook, W. S.

2014-12-01

In semi-arid rangeland environments understanding how surface and subsurface flow processes and their interactions are influenced by watershed and rainfall characteristics is critical. However, it is difficult to resolve the temporal variations between mechanisms controlling these processes and challenging to obtain field measurements that document their interactions. Better insight into how these complex systems respond hydrologically is necessary in order to refine hydrologic models and decision support tools. We are conducting field studies integrating high resolution, two-dimensional surface electrical resistivity imaging (ERI) with variable intensity rainfall simulation, to quantify real-time partitioning of rainfall into surface and subsurface response. These studies are being conducted at the hillslope scale on long-term runoff plots on four different ecological sites in the Upper Crow Creek Watershed in southeastern Wyoming. Variable intensity rainfall rates were applied using the Walnut Gulch Rainfall Simulator in which intensities were increased incrementally from 49 to 180 mm hr-1 and steady-state runoff rates for each intensity were measured. Two 13.5 m electrode arrays at 0.5 m spacing were positioned on the surface perpendicular to each plot and potentials were measured at given time intervals prior to, during and following simulations using a dipole-dipole array configuration. The configuration allows for a 2.47 m depth of investigation in which magnitude and direction of subsurface flux can be determined. We used the calculated steady state infiltration rates to quantify the variability in the partial area runoff response on the ecological sites. Coupling this information with time-lapse difference inversions of ERI data, we are able to track areas of increasing and decreasing resistivity in the subsurface related to localized areas of infiltration during and following rainfall events. We anticipate implementing this method across a variety of ecological sites in the Upper Crow Creek in order to characterize the variable hydrologic response of this complex rangeland watershed. This information is being used to refine current physically based hydrologic models and watershed assessment tools.

AMISS - Active and passive MIcrowaves for Security and Subsurface imaging

NASA Astrophysics Data System (ADS)

Soldovieri, Francesco; Slob, Evert; Turk, Ahmet Serdar; Crocco, Lorenzo; Catapano, Ilaria; Di Matteo, Francesca

2013-04-01

The FP7-IRSES project AMISS - Active and passive MIcrowaves for Security and Subsurface imaging is based on a well-combined network among research institutions of EU, Associate and Third Countries (National Research Council of Italy - Italy, Technische Universiteit Delft - The Netherlands, Yildiz Technical University - Turkey, Bauman Moscow State Technical University - Russia, Usikov Institute for Radio-physics and Electronics and State Research Centre of Superconductive Radioelectronics "Iceberg" - Ukraine and University of Sao Paulo - Brazil) with the aims of achieving scientific advances in the framework of microwave and millimeter imaging systems and techniques for security and safety social issues. In particular, the involved partners are leaders in the scientific areas of passive and active imaging and are sharing their complementary knowledge to address two main research lines. The first one regards the design, characterization and performance evaluation of new passive and active microwave devices, sensors and measurement set-ups able to mitigate clutter and increase information content. The second line faces the requirements to make State-of-the-Art processing tools compliant with the instrumentations developed in the first line, suitable to work in electromagnetically complex scenarios and able to exploit the unexplored possibilities offered by new instrumentations. The main goals of the project are: 1) Development/improvement and characterization of new sensors and systems for active and passive microwave imaging; 2) Set up, analysis and validation of state of art/novel data processing approach for GPR in critical infrastructure and subsurface imaging; 3) Integration of state of art and novel imaging hardware and characterization approaches to tackle realistic situations in security, safety and subsurface prospecting applications; 4) Development and feasibility study of bio-radar technology (system and data processing) for vital signs detection and detection/characterization of human beings in complex scenarios. These goals are planned to be reached following a plan of research activities and researchers secondments which cover a period of three years. ACKNOWLEDGMENTS This research has been performed in the framework of the "Active and Passive Microwaves for Security and Subsurface imaging (AMISS)" EU 7th Framework Marie Curie Actions IRSES project (PIRSES-GA-2010-269157).

Fuzzy Logic Modelling and Hidden Geodynamic Parameters of Earth: What is the role of Fluid Pathaways and Hydrothermal Stages on the Mineralization Variations of Kozbudaklar Pluton over Southern Uludag

NASA Astrophysics Data System (ADS)

Kocaturk, Huseyin; Kumral, Mustafa

2016-04-01

Plate tectonics is one of the most illustrated theory and biggest geo-dynamic incident on earth surface and sub-surface for the earth science. Tectonic settlement, rock forming minerals, form of stratigraphy, ore genesis processes, crystal structures and even rock textures are all related with plate tectonic. One of the most known region of Turkey is Southern part of Uludaǧ and has been defined with three main lithological union. Region is formed with metamorphics, ophiolites and magmatic intrusions which are generally I-type granodiorites. Also these intrusion related rocks has formed and altered by high grade hydrothermal activity. This study approaches to understand bigger to smaller frameworks of these processes which between plate tectonics and fluid pathways. Geodynamic related fuzzy logic modelling is present us compact conclusion report about structural associations for the economic generations. Deformation structures and fluid pathways which related with plate tectonics progressed on our forearc system and each steps of dynamic movements of subducting mechanism has been seemed affect both hydrothermal stages and mineral variations together. Types of each deformation structure and mineral assemblages has characterized for flux estimations which can be useful for subsurface mapping. Geoanalytical results showed us clear characteristic stories for mutual processes. Determined compression and release directions on our map explains not only hydrothermal stages but also how succesion of intrusions changes. Our fuzzy logic models intersect sections of physical and chemical interactions of study field. Researched parameters like mafic minerals and enclave ratios on different deformation structures, cross sections of structures and relative existing sequence are all changes with different time periods like geochemical environment and each vein. With the combined informations in one scene we can transact mineralization processes about region which occurs in different stages such as subducting slabs, arc volcanism, subsurface flux estimates related orogenic processes, and other geochemical effects of plate movements. Keywords: Hydrothermal Stages, Flux Estimate, Southern Region of Uludaǧ, Subsurface Mapping

Structural control on the deep hydrogeological and geothermal aquifers related to the fractured Campanian-Miocene reservoirs of north-eastern Tunisia foreland constrained by subsurface data

NASA Astrophysics Data System (ADS)

Khomsi, Sami; Echihi, Oussema; Slimani, Naji

2012-03-01

A set of different data including high resolution seismic sections, petroleum wire-logging well data, borehole piezometry, structural cross-sections and outcrop analysis allowed us to characterise the tectonic framework, and its relationships with the deep aquifers seated in Cretaceous-Miocene deep reservoirs. The structural framework, based on major structures, controls the occurrence of deep aquifers and sub-basin aquifer distributions. Five structural domains can be defined, having different morphostructural characteristics. The northernmost domain lying on the north-south axis and Zaghouan thrust system is a domain of recharge by underflow of the different subsurface reservoirs and aquifers from outcrops of highly fractured reservoirs. On the other hand, the morphostructural configuration controls the piezometry of underground flows in the Plio-Quaternary unconfined aquifer. In the subsurface the Late Cretaceous-Miocene reservoirs are widespread with high thicknesses in many places and high porosities and connectivities especially along major fault corridors and on the crestal parts of major anticlines. Among all reservoirs, the Oligo-Miocene, detritic series are widespread and present high cumulative thicknesses. Subsurface and fieldwork outline the occurrence of 10 fractured sandy reservoirs for these series with packages having high hydrodynamic and petrophysical characteristics. These series show low salinities (maximum 5 g/l) in the northern part of the study area and will constitute an important source of drinkable water for the next generations. A regional structural cross-section is presented, compiled from all the different data sets, allowing us to define the major characteristics of the hydrogeological-hydrogeothermal sub-basins. Eight hydrogeological provinces are defined from north-west to south-east. A major thermal anomaly is clearly identified in the south-eastern part of the study area in Sfax-Sidi Il Itayem. This anomaly is possibly related to major faults pertaining to the Sirt basin and controlled by a deep thermal anomaly. Many exploration targets are identified especially along the Cherichira-Kondar thrust where the Oligocene subcropping reservoirs are well developed. They are highly fractured and show good hydrodynamic characteristics.

PROCEEDINGS OF THE CROSS DISCIPLINE ECOSYTEM MODELING AND ANALYSIS WORKSHOP

EPA Science Inventory

The complexity of environmental problems we face now and in the future is ever increasing. Process linkages among air, land, surface and subsurface water require interdisciplinary modeling approaches. The dynamics of land use change spurred by population and economic growth, ...

COMPLEX CONDUCTIVITY RESPONSE TO NANOMATERIALS IN A SAND MATRIX

EPA Science Inventory

Nano-scale metallic particles are being used with increasing frequency in a variety of industrial, medical, and environmental remediation applcations. The fate and transport of such materials in the subsurface is not fully understood, neither is the impact of these materials on ...

Probability of detection of internal voids in structural ceramics using microfocus radiography

NASA Technical Reports Server (NTRS)

Baaklini, G. Y.; Roth, D. J.

1986-01-01

The reliability of microfocous X-radiography for detecting subsurface voids in structural ceramic test specimens was statistically evaluated. The microfocus system was operated in the projection mode using low X-ray photon energies (20 keV) and a 10 micro m focal spot. The statistics were developed for implanted subsurface voids in green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Problems associated with void implantation are discussed. Statistical results are given as probability-of-detection curves at a 95 precent confidence level for voids ranging in size from 20 to 528 micro m in diameter.

Probability of detection of internal voids in structural ceramics using microfocus radiography

NASA Technical Reports Server (NTRS)

Baaklini, G. Y.; Roth, D. J.

1985-01-01

The reliability of microfocus x-radiography for detecting subsurface voids in structural ceramic test specimens was statistically evaluated. The microfocus system was operated in the projection mode using low X-ray photon energies (20 keV) and a 10 micro m focal spot. The statistics were developed for implanted subsurface voids in green and sintered silicon carbide and silicon nitride test specimens. These statistics were compared with previously-obtained statistics for implanted surface voids in similar specimens. Problems associated with void implantation are discussed. Statistical results are given as probability-of-detection curves at a 95 percent confidence level for voids ranging in size from 20 to 528 micro m in diameter.

3D Seismic Experimentation and Advanced Processing/Inversion Development for Investigations of the Shallow Subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levander, Alan Richard; Zelt, Colin A.

2015-03-17

The work plan for this project was to develop and apply advanced seismic reflection and wide-angle processing and inversion techniques to high resolution seismic data for the shallow subsurface to seismically characterize the shallow subsurface at hazardous waste sites as an aid to containment and cleanup activities. We proposed to continue work on seismic data that we had already acquired under a previous DoE grant, as well as to acquire additional new datasets for analysis. The project successfully developed and/or implemented the use of 3D reflection seismology algorithms, waveform tomography and finite-frequency tomography using compressional and shear waves for highmore » resolution characterization of the shallow subsurface at two waste sites. These two sites have markedly different near-surface structures, groundwater flow patterns, and hazardous waste problems. This is documented in the list of refereed documents, conference proceedings, and Rice graduate theses, listed below.« less

Surface assessment of CaF2 deep-ultraviolet and vacuum-ultraviolet optical components by the quasi-Brewster angle technique.

PubMed

Wang, Jue; Maier, Robert L

2006-08-01

The requirements for optical components have drastically increased for the deep-ultraviolet and vacuum-ultraviolet spectral regions. Low optical loss, high laser damage threshold, and long lifetime fluoride optics are required for microlithographic applications. A nondestructive quasi-Brewster angle technique (qBAT) has been developed for evaluating the quality of optical surfaces including both top surface and subsurface information. By using effective medium approximation, the negative quasi-Brewster angle shift at wavelengths longer than 200 nm has been used to model the distribution of subsurface damage, whereas the positive quasi-Brewster angle shift for wavelengths shorter than 200 nm has been explained by subsurface contamination. The top surface roughness depicted by the qBAT is consistent with atomic force microscopy measurements. The depth and the microporous structure of the subsurface damage measured by the qBAT has been confirmed by magnetorheological finishing. The technique has been extended to evaluate both polished and antireflection-coated CaF(2) components.

Induced seismicity constraints on subsurface geological structure, Paradox Valley, Colorado

NASA Astrophysics Data System (ADS)

Block, Lisa V.; Wood, Christopher K.; Yeck, William L.; King, Vanessa M.

2015-02-01

Precise relative hypocentres of seismic events induced by long-term fluid injection at the Paradox Valley Unit (PVU) brine disposal well provide constraints on the subsurface geological structure and compliment information available from deep seismic reflection and well data. We use the 3-D spatial distribution of the hypocentres to refine the locations, strikes, and throws of subsurface faults interpre­ted previously from geophysical surveys and to infer the existence of previously unidentified subsurface faults. From distinct epicentre lineations and focal mechanism trends, we identify a set of conjugate fracture orientations consistent with shear-slip reactivation of late-Palaeozoic fractures over a widespread area, as well as an additional fracture orientation present only near the injection well. We propose simple Mohr-Coulomb fracture models to explain these observations. The observation that induced seismicity preferentially occurs along one of the identified conjugate fracture orientations can be explained by a rotation in the direction of the regional maximum compressive stress from the time when the fractures were formed to the present. Shear slip along the third fracture orientation observed near the injection well is inconsistent with the current regional stress field and suggests a local rotation of the horizontal stresses. The detailed subsurface model produced by this analysis provides important insights for anticipating spatial patterns of future induced seismicity and for evaluation of possible additional injection well sites that are likely to be seismically and hydrologically isolated from the current well. In addition, the interpreted fault patterns provide constraints for estimating the maximum magnitude earthquake that may be induced, and for building geomechanical models to simulate pore pressure diffusion, stress changes and earthquake triggering.

Geomicrobiology and Metagenomics of Terrestrial Deep Subsurface Microbiomes.

PubMed

Itävaara, M; Salavirta, H; Marjamaa, K; Ruskeeniemi, T

2016-01-01

Fractures in the deep subsurface of Earth's crust are inhabited by diverse microbial communities that participate in biogeochemical cycles of the Earth. Life on Earth, which arose c. 3.5-4.0 billion years ago, reaches down at least 5 km in the crust. Deep mines, caves, and boreholes have provided scientists with opportunities to sample deep subsurface microbiomes and to obtain information on the species diversity and functions. A wide variety of bacteria, archaea, eukaryotes, and viruses are now known to reside in the crust, but their functions are still largely unknown. The crust at different depths has varying geological composition and hosts endemic microbiomes accordingly. The diversity is driven by geological formations and gases evolving from deeper depths. Cooperation among different species is still mostly unexplored, but viruses are known to restrict density of bacterial and archaeal populations. Due to the complex growth requirements of the deep subsurface microbiomes, the new knowledge about their diversity and functions is mostly obtained by molecular methods, eg, meta'omics'. Geomicrobiology is a multidisciplinary research area combining disciplines from geology, mineralogy, geochemistry, and microbiology. Geomicrobiology is concerned with the interaction of microorganisms and geological processes. At the surface of mineralogical or rock surfaces, geomicrobial processes occur mainly under aerobic conditions. In the deep subsurface, however, the environmental conditions are reducing and anaerobic. The present chapter describes the world of microbiomes in deep terrestrial geological environments as well as metagenomic and metatranscriptomic methods suitable for studies of these enigmatic communities. Copyright © 2016 Elsevier Inc. All rights reserved.

Entropy-Based Classification of Subsurface Scatterers: A Valuable Tool for the Analysis of Data Obtained by the Fully Polarimetric WISDOM Radar

NASA Astrophysics Data System (ADS)

Plettemeier, D.; Statz, C.; Hahnel, R.; Benedix, W. S.; Hamran, S. E.; Ciarletti, V.

2016-12-01

The "Water Ice Subsurface Deposition on Mars" Experiment (WISDOM) is a Ground Penetrating Radar (GPR) and part of the 2020 ExoMars Rover payload. It will be the first GPR operating on a planetary rover and the first fully polarimetric radar tasked at probing the subsurface of Mars. WISDOM operates at frequencies between 500 MHz and 3 GHz yielding a centimetric resolution and a penetration depth of about 3 meters in Martian soil. Its prime scientific objective is the detailed characterization of the material distribution within the first few meters of the Martian subsurface as a contribution to the search for evidence of past life. For the first time, WISDOM will give access to the geological structure, electromagnetic nature, and hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors at an unprecedented resolution and, due to the fully polarimetric measurements, amount of information. Furthermore, a "real time" subsurface analysis will support the drill operations by identifying locations of high scientific interest and low risk. Key element in the WISDOM data analysis is the fast and reliable classification and correct localization of subsurface scatterers and layers. The fully polarimetric nature of the WISDOM measurements allows the use of the entropy-alpha decomposition (H-alpha). This method enables the classification of reconstructed images of the subsurface (obtained by inverse imaging algorithms, e.g. f-k migration) with regard to the main scattering mechanisms of geological features present in the image of the subsurface. It is, for example, possible to differentiate smooth surfaces, rough surfaces, isolated spherical scatterers, double- and bounce scattering, anisotropic scatterers, clouds of small scatterers of similar shape as well as layers of oblate spheroids. Preliminary tests under laboratory conditions suggest the feasibility and value of the approach for the classification of geological features in the Martian subsurface in the context of WISDOM data processing and operations. It is a fast and reliable tool leveraging the whole amount of information provided by the fully polarimetric WISDOM Radar.

Improving surface-subsurface water budgeting using high resolution satellite imagery applied on a brownfield.

PubMed

Dujardin, J; Batelaan, O; Canters, F; Boel, S; Anibas, C; Bronders, J

2011-01-15

The estimation of surface-subsurface water interactions is complex and highly variable in space and time. It is even more complex when it has to be estimated in urban areas, because of the complex patterns of the land-cover in these areas. In this research a modeling approach with integrated remote sensing analysis has been developed for estimating water fluxes in urban environments. The methodology was developed with the aim to simulate fluxes of contaminants from polluted sites. Groundwater pollution in urban environments is linked to patterns of land use and hence it is essential to characterize the land cover in a detail. An object-oriented classification approach applied on high-resolution satellite data has been adopted. To assign the image objects to one of the land-cover classes a multiple layer perceptron approach was adopted (Kappa of 0.86). Groundwater recharge has been simulated using the spatially distributed WetSpass model and the subsurface water flow using MODFLOW in order to identify and budget water fluxes. The developed methodology is applied to a brownfield case site in Vilvoorde, Brussels (Belgium). The obtained land use map has a strong impact on the groundwater recharge, resulting in a high spatial variability. Simulated groundwater fluxes from brownfield to the receiving River Zenne were independently verified by measurements and simulation of groundwater-surface water interaction based on thermal gradients in the river bed. It is concluded that in order to better quantify total fluxes of contaminants from brownfields in the groundwater, remote sensing imagery can be operationally integrated in a modeling procedure. Copyright © 2010 Elsevier B.V. All rights reserved.

Scaled Anatomical Model Creation of Biomedical Tomographic Imaging Data and Associated Labels for Subsequent Sub-surface Laser Engraving (SSLE) of Glass Crystals

PubMed Central

Dethlefs, Christopher R.; Piotrowicz, Justin; Van Avermaete, Tony; Maki, Jeff; Gerstler, Steve; Leevy, W. M.

2017-01-01

Biomedical imaging modalities like computed tomography (CT) and magnetic resonance (MR) provide excellent platforms for collecting three-dimensional data sets of patient or specimen anatomy in clinical or preclinical settings. However, the use of a virtual, on-screen display limits the ability of these tomographic images to fully convey the anatomical information embedded within. One solution is to interface a biomedical imaging data set with 3D printing technology to generate a physical replica. Here we detail a complementary method to visualize tomographic imaging data with a hand-held model: Sub Surface Laser Engraving (SSLE) of crystal glass. SSLE offers several unique benefits including: the facile ability to include anatomical labels, as well as a scale bar; streamlined multipart assembly of complex structures in one medium; high resolution in the X, Y, and Z planes; and semi-transparent shells for visualization of internal anatomical substructures. Here we demonstrate the process of SSLE with CT data sets derived from pre-clinical and clinical sources. This protocol will serve as a powerful and inexpensive new tool with which to visualize complex anatomical structures for scientists and students in a number of educational and research settings. PMID:28518066

Collaborative Research: Nanopore Confinement of C-H-O Mixed Volatile Fluids Relevant to Subsurface Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grady, Brian P.

2015-03-11

The scientific objective of this proposal was to obtain a fundamental atomic- to macro-scale understanding of the sorptivity, structure and dynamics of simple and complex hydrocarbon (HC) fluids at mineral surfaces or within nanoporous matrices over temperatures, pressures and compositions encountered in near-surface and shallow crustal environments. The research supported by this award was complementary to that conducted by the group of Prof. David cole at Ohio State University. The scope of the present award was to utilize molecular-level modeling to provide critically important insights into the interfacial properties of mineral-volatile systems, assist in the interpretation of experimental data andmore » predict fluid behavior beyond the limits of current experimental capability. During the past three years the effort has focused primarily on the behavior of C-H volatiles including methane (CH 4) and propane (C 3H 8), mixed-volatile systems including hydrocarbon - CO 2 with and without H 2O present. The long-range goal is to quantitatively link structure, dynamics and reactivity in complex mineral-/C-H-O systems from the atomic to the molecular to the macroscopic levels. The results are relevant to areas of growing importance such as gas shale, HC-bearing hydrothermal systems, and CO 2 storage.« less

Electrolyte-induced surface transformation and transition-metal dissolution of fully delithiated LiNi 0.8Co 0.15Al 0.05O 2

DOE PAGES

Faenza, Nicholas V.; Lebens-Higgins, Zachary W.; Mukherjee, Pinaki; ...

2017-06-08

Here, enabling practical utilization of layered Rmore » $$\\bar{3}$$ m positive electrodes near full delithiation requires an enhanced understanding of the complex electrode–electrolyte interactions that often induce failure. Using Li[Ni 0.8Co 0.15Al 0.05]O 2 (NCA) as a model layered compound, the chemical and structural stability in a strenuous thermal and electrochemical environment was explored. Operando microcalorimetry and electrochemical impedance spectroscopy identified a fingerprint for a structural decomposition and transition-metal dissolution reaction that occurs on the positive electrode at full delithiation. Surface-sensitive characterization techniques, including X-ray absorption spectroscopy and high-resolution transmission electron microscopy, measured a structural and morphological transformation of the surface and subsurface regions of NCA. Despite the bulk structural integrity being maintained, NCA surface degradation at a high state of charge induces excessive transition-metal dissolution and significant positive electrode impedance development, resulting in a rapid decrease in electrochemical performance. Additionally, the impact of electrolyte salt, positive electrode surface area, and surface Li 2CO 3 content on the magnitude and character of the dissolution reaction was studied.« less

Lamb wave line sensing for crack detection in a welded stiffener.

PubMed

An, Yun-Kyu; Kim, Jae Hong; Yim, Hong Jae

2014-07-18

This paper proposes a novel Lamb wave line sensing technique for crack detection in a welded stiffener. The proposed technique overcomes one of the biggest technical challenges of Lamb wave crack detection for real structure applications: crack-induced Lamb waves are often mixed with multiple reflections from complex waveguides. In particular, crack detection in a welded joint, one of the structural hot spots due to stress concentration, is accompanied by reflections from the welded joint as well as a crack. Extracting and highlighting crack-induced Lamb wave modes from Lamb wave responses measured at multi-spatial points along a single line can be accomplished through a frequency-wavenumber domain analysis. The advantages of the proposed technique enable us not only to enhance the crack detectability in the welded joint but also to minimize false alarms caused by environmental and operational variations by avoiding the direct comparison with the baseline data previously accumulated from the pristine condition of a target structure. The proposed technique is experimentally and numerically validated in vertically stiffened metallic structures, revealing that it successfully identifies and localizes subsurface cracks, regardless of the coexistence with the vertical stiffener.

Electrolyte-Induced Surface Transformation and Transition-Metal Dissolution of Fully Delithiated LiNi0.8Co0.15Al0.05O2.

PubMed

Faenza, Nicholas V; Lebens-Higgins, Zachary W; Mukherjee, Pinaki; Sallis, Shawn; Pereira, Nathalie; Badway, Fadwa; Halajko, Anna; Ceder, Gerbrand; Cosandey, Frederic; Piper, Louis F J; Amatucci, Glenn G

2017-09-19

Enabling practical utilization of layered R3̅m positive electrodes near full delithiation requires an enhanced understanding of the complex electrode-electrolyte interactions that often induce failure. Using Li[Ni 0.8 Co 0.15 Al 0.05 ]O 2 (NCA) as a model layered compound, the chemical and structural stability in a strenuous thermal and electrochemical environment was explored. Operando microcalorimetry and electrochemical impedance spectroscopy identified a fingerprint for a structural decomposition and transition-metal dissolution reaction that occurs on the positive electrode at full delithiation. Surface-sensitive characterization techniques, including X-ray absorption spectroscopy and high-resolution transmission electron microscopy, measured a structural and morphological transformation of the surface and subsurface regions of NCA. Despite the bulk structural integrity being maintained, NCA surface degradation at a high state of charge induces excessive transition-metal dissolution and significant positive electrode impedance development, resulting in a rapid decrease in electrochemical performance. Additionally, the impact of electrolyte salt, positive electrode surface area, and surface Li 2 CO 3 content on the magnitude and character of the dissolution reaction was studied.

Frequency domain electromagnetic induction survey in the intertidal zone: Limitations of low-induction-number and depth of exploration

NASA Astrophysics Data System (ADS)

Delefortrie, Samuël; Saey, Timothy; Van De Vijver, Ellen; De Smedt, Philippe; Missiaen, Tine; Demerre, Ine; Van Meirvenne, Marc

2014-01-01

Subsurface investigation in the Belgian intertidal zone is severely complicated due to high heterogeneity and tides. Near-surface geophysical techniques can offer assistance since they allow fast surveying and collection of high spatial density data and frequency domain electromagnetic induction (EMI) was chosen for archaeological prospection on the Belgian shore. However, in the intertidal zone the effects of extreme salinity compromise validity of low-induction-number (LIN) approximated EMI data. In this paper, the effects of incursion of seawater on multi-receiver EMI data are investigated by means of survey results, field observations, cone penetration tests and in-situ electrical conductivity measurements. The consequences of LIN approximation breakdown were researched. Reduced depth of investigation of the quadrature-phase (Qu) response and a complex interpretation of the in-phase response were confirmed. Nonetheless, a high signal-to-noise ratio of the Qu response and viable data with regard to shallow subsurface investigation were also evidenced, allowing subsurface investigation in the intertidal zone.

Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

NASA Technical Reports Server (NTRS)

Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

2016-01-01

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. Here we use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals an Approximately 72 km thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

PubMed Central

Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Manoj, Chandrasekharan; Olsen, Nils

2016-01-01

The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. We use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals a ≈72-km-thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere. PMID:27704045

The potential of audiomagnetotellurics in the study of geothermal fields: A case study from the northern segment of the La Candelaria Range, northwestern Argentina

NASA Astrophysics Data System (ADS)

Barcelona, Hernan; Favetto, Alicia; Peri, Veronica Gisel; Pomposiello, Cristina; Ungarelli, Carlo

2013-01-01

Despite its reduced penetration depth, audiomagnetotelluric (AMT) studies can be used to determine a broad range of features related to little studied geothermal fields. This technique requires a stepwise interpretation of results taking into consideration diverse information (e.g. topographic, hydrological, geological and/or structural data) to constrain the characteristics of the study area. In this work, an AMT study was performed at the hot springs in the northern segment of the La Candelaria Range in order to characterize the area at depth. Geometric aspects of the shallow subsurface were determined based on the dimensional and distortion analysis of the impedance tensors. Also, the correlation between structural features and regional strikes allowed us to define two geoelectric domains, useful to determine the controls on fluid circulation. The subsurface resistivity distribution was determined through 1D and 2D models. The patterns of the 1D models were compared with the morpho-structure of the range. Shallow and deep conductive zones were defined and a possible shallow geothermal system scheme proposed. A strong correlation was found between the AMT results and the geological framework of the region, showing the relevance of using AMT in geothermal areas during the early stages of subsurface prospecting.

Lithology and characteristic of landslide in Gombel Hill by 2D geoelectric resistivity method using dipole-dipole configuration

NASA Astrophysics Data System (ADS)

Setyawan, Agus; Satria Fikri, Muhammad; Endro Suseno, Jatmiko; Fuad, Muhamad

2018-05-01

Gombel hill locates at Semarang, Central Java, Indonesia. Base on Semarang’s susceptiblity map zone, Gombel hill is belong to high susceptibility and instability zone. Instability may cause faults to Gombel hill area, unfortunately the geosciences research in Gombel is still lack. The geophysical survey has been conducted using 2D geoelectric resistivity method with dipole – dipole configuration to identify the lithology of landslide at Gombel hill. The data have been collected from three lines. The first and third line have 100 m length, and the second line have 80 m length with 5 m space in each lines. The data were processed and modelled using Res2Dinv software. From the first line, suspected there are two layers which formed the structure of the subsurface. The second line suspected there are three layers which formed the structure of the subsurface. And the last line suspected there are two layers which formed the structure of the subsurface. Overall, the landslide of Gombel hill area can be found with depth 5 m – 6 m and found at contact between clay and clay rock layer. We expect the results can be used for mitigation hazard and planning the developing infrastructure in Gombel area.

Integrated geoelectrical survey for groundwater and shallow subsurface evaluation: case study at Siliyin spring, El-Fayoum, Egypt

NASA Astrophysics Data System (ADS)

Metwaly, Mohamed; El-Qady, Gad; Massoud, Usama; El-Kenawy, Abeer; Matsushima, Jun; Al-Arifi, Nasser

2010-09-01

Siliyin spring is one of the many natural fresh water springs in the Western Desert of Egypt. It is located at the central part of El-Fayoum Delta, which is a potential place for urban developments and touristic activities. Integrated geoelectrical survey was conducted to facilitate mapping the groundwater resources and the shallow subsurface structures in the area. Twenty-eight transient electromagnetic (TEM) soundings, three vertical electrical soundings (VES) and three electrical resistivity tomography (ERT) profiles were carried out around the Siliyin spring location. The dense cultivation, the rugged topography and the existence of infra structure in the area hindered acquiring more data. The TEM data were inverted jointly with the VES and ERT, and constrained by available geological information. Based on the inversion results, a set of geoelectrical cross-sections have been constructed. The shallow sand to sandy clay layer that forms the shallow aquifer has been completely mapped underneath and around the spring area. Flowing of water from the Siliyin spring is interconnected with the lateral lithological changes from clay to sand soil. Exploration of the extension of Siliyin spring zone is recommended. The interpretation emphasizes the importance of integrating the geoelectrical survey with the available geological information to obtain useful, cheap and fast lithological and structural subsurface information.

Cu-rGO subsurface layer creation on copper substrate and its resistance to oxidation

NASA Astrophysics Data System (ADS)

Pietrzak, Katarzyna; Strojny-Nędza, Agata; Olesińska, Wiesława; Bańkowska, Anna; Gładki, Andrzej

2017-11-01

On the basis of a specially designed experiment, this paper presents a model, which is an attempt to explain the mechanism of formatting and creating oxidation resistance of Cu-rGO subsurface layers. Practically zero chemical affinity of copper to carbon is a fundamental difficulty in creating composite structures of Cu-C, properties which are theoretically possible to estimate. In order to bind the thermally reduced graphene oxide with copper surface, the effect of structural rebuilding of the copper oxide, in the process of annealing in a nitrogen atmosphere, have been used. On intentionally oxidized and anoxic copper substrates the dispersed graphene oxide (GO) and thermally reduced graphene oxide (rGO) were loaded. Annealing processes after the binding effects of both graphene oxide forms to Cu substrates were tested. The methods for high-resolution electron microscopy were found subsurface rGO-Cu layer having a substantially greater resistance to oxidation than pure copper. The mechanism for the effective resistance to oxidation of the Cu-rGO has been presented in a hypothetical form.

Final Report, DOE Early Career Award: Predictive modeling of complex physical systems: new tools for statistical inference, uncertainty quantification, and experimental design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marzouk, Youssef

Predictive simulation of complex physical systems increasingly rests on the interplay of experimental observations with computational models. Key inputs, parameters, or structural aspects of models may be incomplete or unknown, and must be developed from indirect and limited observations. At the same time, quantified uncertainties are needed to qualify computational predictions in the support of design and decision-making. In this context, Bayesian statistics provides a foundation for inference from noisy and limited data, but at prohibitive computional expense. This project intends to make rigorous predictive modeling *feasible* in complex physical systems, via accelerated and scalable tools for uncertainty quantification, Bayesianmore » inference, and experimental design. Specific objectives are as follows: 1. Develop adaptive posterior approximations and dimensionality reduction approaches for Bayesian inference in high-dimensional nonlinear systems. 2. Extend accelerated Bayesian methodologies to large-scale {\\em sequential} data assimilation, fully treating nonlinear models and non-Gaussian state and parameter distributions. 3. Devise efficient surrogate-based methods for Bayesian model selection and the learning of model structure. 4. Develop scalable simulation/optimization approaches to nonlinear Bayesian experimental design, for both parameter inference and model selection. 5. Demonstrate these inferential tools on chemical kinetic models in reacting flow, constructing and refining thermochemical and electrochemical models from limited data. Demonstrate Bayesian filtering on canonical stochastic PDEs and in the dynamic estimation of inhomogeneous subsurface properties and flow fields.« less

Hypervelocity impacts into ice-topped layered targets: Investigating the effects of ice crust thickness and subsurface density on crater morphology

NASA Astrophysics Data System (ADS)

Harriss, Kathryn H.; Burchell, Mark J.

2017-07-01

Many bodies in the outer solar system are theorized to have an ice shell with a different subsurface material below, be it chondritic, regolith, or a subsurface ocean. This layering can have a significant influence on the morphology of impact craters. Accordingly, we have undertaken laboratory hypervelocity impact experiments on a range of multilayered targets, with interiors of water, sand, and basalt. Impact experiments were undertaken using impact speeds in the range of 0.8-5.3 km s-1, a 1.5 mm Al ball bearing projectile, and an impact incidence of 45°. The surface ice crust had a thickness between 5 and 50 mm, i.e., some 3-30 times the projectile diameter. The thickness of the ice crust as well as the nature of the subsurface layer (liquid, well consolidated, etc.) have a marked effect on the morphology of the resulting impact crater, with thicker ice producing a larger crater diameter (at a given impact velocity), and the crater diameter scaling with impact speed to the power 0.72 for semi-infinite ice, but with 0.37 for thin ice. The density of the subsurface material changes the structure of the crater, with flat crater floors if there is a dense, well-consolidated subsurface layer (basalt) or steep, narrow craters if there is a less cohesive subsurface (sand). The associated faulting in the ice surface is also dependent on ice thickness and the substrate material. We find that the ice layer (in impacts at 5 km s-1) is effectively semi-infinite if its thickness is more than 15.5 times the projectile diameter. Below this, the crater diameter is reduced by 4% for each reduction in ice layer thickness equal to the impactor diameter. Crater depth is also affected. In the ice thickness region, 7-15.5 times the projectile diameter, the crater shape in the ice is modified even when the subsurface layer is not penetrated. For ice thicknesses, <7 times the projectile diameter, the ice layer is breached, but the nature of the resulting crater depends heavily on the subsurface material. If the subsurface is noncohesive (loose) material, a crater forms in it. If it is dense, well-consolidated basalt, no crater forms in the exposed subsurface layer.

Scaling in soils and other complex porous media

USDA-ARS?s Scientific Manuscript database

Scaling remains one of the most challenging topics in earth and environmental sciences, forming a basis for our understanding of process development across the multiple scales which make up the subsurface environment. Understanding and succinct representation of scaling properties can lead to the un...

State-of-stress in magmatic rift zones: Predicting the role of surface and subsurface topography

NASA Astrophysics Data System (ADS)

Oliva, S. J. C.; Ebinger, C.; Rivalta, E.; Williams, C. A.

2017-12-01

Continental rift zones are segmented along their length by large fault systems that form in response to extensional stresses. Volcanoes and crustal magma chambers cause fundamental changes to the density structure, load the plates, and alter the state-of-stress within the crust, which then dictates fracture orientation. In this study, we develop geodynamic models scaled to a < 7 My rift sector in the Eastern rift, East Africa where geophysical imaging provides tight constraints on subsurface structure, petrologic and thermodynamic studies constrain material densities, and seismicity and structural analyses constrain active and time-averaged kinematics. This area is an ideal test area because a 60º stress rotation is observed in time-averaged fault and magma intrusion, and in local seismicity, and because this was the site of a large volume dike intrusion and seismic sequence in 2007. We use physics-based 2D and 3D models (analytical and finite elements) constrained by data from active rift zones to quantify the effects of loading on state-of-stress. By modeling varying geometric arrangements, and density contrasts of topographic and subsurface loads, and with reasonable regional extensional forces, the resulting state-of-stress reveals the favored orientation for new intrusions. Although our models are generalized, they allow us to evaluate whether a magmatic system (surface and subsurface) can explain the observed stress rotation, and enable new intrusions, new faults, or fault reactivation with orientations oblique to the main border faults. Our results will improve our understanding of the different factors at play in these extensional regimes, as well as contribute to a better assessment of the hazards in the area.

Reversible structural modulation of Fe-Pt bimetallic surfaces and its effect on reactivity.

PubMed

Ma, Teng; Fu, Qiang; Su, Hai-Yan; Liu, Hong-Yang; Cui, Yi; Wang, Zhen; Mu, Ren-Tao; Li, Wei-Xue; Bao, Xin-He

2009-05-11

Tunable surface: The surface structure of the Fe-Pt bimetallic catalyst can be reversibly modulated between the iron-oxide-rich Pt surface and the Pt-skin structure with subsurface Fe via alternating reduction and oxidation treatments (see figure). The regenerated active Pt-skin structure is active in reactions involving CO and/or O.

Remote Sensing of Subsurface Microbial Transformations

NASA Astrophysics Data System (ADS)

Williams, K. H.; Ntarlagiannis, D.; Slater, L.; Long, P.; Dohnalkova, A.; Hubbard, S. S.; Banfield, J. F.

2004-12-01

Understanding how microorganisms influence the physical and chemical properties of the subsurface is hindered by our inability to detect microbial dynamics in real time with high spatial resolution. Here we have used non-invasive geophysical methods to monitor biomineralization and related processes during biostimulation at both laboratory and field scales. Alterations in saturated sediment characteristics resulting from microbe-mediated transformations were concomitant with changes in complex resistivity, spontaneous potential, and acoustic wave signatures. Variability in complex resistivity and acoustic wave amplitudes appears tied to the nucleation, growth, and development of nanoparticulate precipitates along grain surfaces and within the pore space. In contrast, time-varying spontaneous potentials appear primarily sensitive to the electrochemical gradients resulting from metabolic pathways, such as iron- and sulfate-reduction. Furthermore, they enable us to track mobile fronts of active respiration that arise due to microbial chemotaxis. In this way, geophysical data may be used to image the distribution of mineral precipitates, biomass, and biogeochemical fronts evolving over time and suggest the ability to remotely monitor contaminated aquifers undergoing bioremediation.

Under the pile. Understanding subsurface dynamics of historical cities trough geophysical models interpretation

NASA Astrophysics Data System (ADS)

Bernardes, Paulo; Pereira, Bruno; Alves, Mafalda; Fontes, Luís; Sousa, Andreia; Martins, Manuela; Magalhães, Fernanda; Pimenta, Mário

2017-04-01

Braga is one of the oldest cities of the Iberian NW and as of so, the research team's studying the city's historical core for the past 40 years is often confronted with the unpredictability factor laying beneath an urban site with such a long construction history. In fact, Braga keeps redesigning its urban structure over itself on for the past 2000 years, leaving us with a research object filled with an impressive set of construction footprints from the various planning decisions that were taken in the city along its historical path. Aiming for a predicting understanding of the subsoil, we have used near surface geophysics as an effort of minimizing the areas of intervention for traditional archaeological survey techniques. The Seminário de Santiago integrated geophysical survey is an example of the difficulties of interpreting geophysical models in very complex subsurface scenarios. This geophysical survey was planned in order to aid the requalification project being designed for this set of historical buildings, that are estimated to date back to the 16h century, and that were built over one of the main urban arteries of both roman and medieval layers of Braga. We have used both GPR as well as ERT methods for the geophysical survey, but for the purpose of this article, we will focus in the use of the ERT alone. For the interpretation of the geophysical models we've cross-referenced the dense knowledge existing over the building's construction phases with the complex geophysical data collected, using mathematical processing and volume-based visualization techniques, resorting to the use of Res2Inv©, Paraview© and Voxler® software's. At the same time we tried to pinpoint the noise caused by the past 30 year's infrastructural interventions regarding the replacement of the building's water and sanitation systems and for which we had no design plants, regardless of its recent occurring. The deep impact of this replacement actions revealed by the archaeological trenches, which location was selected from the results of the geophysical models interpretation, revealed to be our main unpredictability factor and, paradoxically, one of its principal results, as it will allow us to be more interpretation efficient in future geophysical surveys in the historical core. As for so, at the present we are designing an integrated geophysical research programme that will hold Braga's historical subsurface as it's open lab, aiming to develop a tool not only for archeologists and geophysicists, but also and foremost to help the city planners to design more informed, efficient and sustainable urban plans for Braga, as the city is very much alive and continually keeps on adding new layers to its urban structure.

Estimation of Global Subsurface Thermal Structure from Satellite Remote Sensing Observations Based on Machine Learning

NASA Astrophysics Data System (ADS)

Su, H.; Yan, X. H.

2017-12-01

Subsurface thermal structure of the global ocean is a key factor that reflects the impact of the global climate variability and change. Accurately determining and describing the global subsurface and deeper ocean thermal structure from satellite measurements is becoming even more important for understanding the ocean interior anomaly and dynamic processes during recent global warming and hiatus. It is essential but challenging to determine the extent to which such surface remote sensing observations can be used to develop information about the global ocean interior. This study proposed a Support Vector Regression (SVR) method to estimate Subsurface Temperature Anomaly (STA) in the global ocean. The SVR model can well estimate the global STA upper 1000 m through a suite of satellite remote sensing observations of sea surface parameters (including Sea Surface Height Anomaly (SSHA), Sea Surface Temperature Anomaly (SSTA), Sea Surface Salinity Anomaly (SSSA) and Sea Surface Wind Anomaly (SSWA)) with in situ Argo data for training and testing at different depth levels. Here, we employed the MSE and R2 to assess SVR performance on the STA estimation. The results from the SVR model were validated for the accuracy and reliability using the worldwide Argo STA data. The average MSE and R2 of the 15 levels are 0.0090 / 0.0086 / 0.0087 and 0.443 / 0.457 / 0.485 for 2-attributes (SSHA, SSTA) / 3-attributes (SSHA, SSTA, SSSA) / 4-attributes (SSHA, SSTA, SSSA, SSWA) SVR, respectively. The estimation accuracy was improved by including SSSA and SSWA for SVR input (MSE decreased by 0.4% / 0.3% and R2 increased by 1.4% / 4.2% on average). While, the estimation accuracy gradually decreased with the increase of the depth from 500 m. The results showed that SSSA and SSWA, in addition to SSTA and SSHA, are useful parameters that can help estimate the subsurface thermal structure, as well as improve the STA estimation accuracy. In future, we can figure out more potential and useful sea surface parameters from satellite remote sensing as input attributes so as to further improve the STA sensing accuracy from machine learning. This study can provide a helpful technique for studying thermal variability in the ocean interior which has played an important role in recent global warming and hiatus from satellite observations over global scale.

P-wave velocity model of mud volcano on the continental slope of the Canadian Beaufort Sea from frequency-domain full waveform inversion

NASA Astrophysics Data System (ADS)

Jang, U. G.; Kang, S. G.; Hong, J. K.; Jin, Y. K.; Dallimore, S.; Riedel, M.; Paull, C. K.

2017-12-01

2014 Expedition ARA05C was a multidisciplinary undertaking conducted in the Canadian Beaufort Sea, Arctic Ocean on the Korean ice breaker IBRV ARAON from August 30 to September 19, 2014. The program was carried out as collaboration between the Korea Polar Research Institute (KOPRI), Geological Survey of Canada (GSC), Monterey Bay Aquarium Research Institute (MBARI), Department of Fisheries and Ocean (DFO) with participation by Bremen University (BARUM). During this expedition, multi-channel seismic (MCS) data were acquired on the outer continental shelf and upper slope of the Canadian Beaufort Sea, totaling 20 lines with 1,000 line-kilometers from September 1 to September 13, 2014. Three MCS survey lines was designed to cross the three submarine mud volcanoes found in the slope at approximate water depth of 290 m, 460 m and 740 m. Submarine mud volcanoes are seafloor structures with positive topography formed by a combination of mud eruption, gas emission, and water seepage from the subsurface. MCS data will allow image subsurface structures of mud volcanoes as identification of fluid migration pathways, however, imaging its subsurface structure is difficult by using conventional seismic data processing procedure, because it is seismically characterized by acoustically transparent facies. Full waveform inversion (FWI) is non-linear data-fitting procedure to estimate the physical properties of the subsurface by minimizing the difference between the observed and modelled data. FWI uses the two-wave wave equation to compute forward/backward wavefield to calculate the gradient direction, therefore it can derive more detailed velocity model beyond travel-time tomography techniques, which use only the kinematics of seismic data, by additional information provided by the amplitude and phase of the seismic waveform. In this study, we suggest P-wave structure of mud volcanos, which were inverted by 2D acoustic FWI. It will be useful to understand the characterization of mud volcanoes on the slope of Canadian Beaufort Sea.

Synthetic seismic monitoring using reverse-time migration and Kirchhoff migration for CO2 sequestration in Korea

NASA Astrophysics Data System (ADS)

Kim, W.; Kim, Y.; Min, D.; Oh, J.; Huh, C.; Kang, S.

2012-12-01

During last two decades, CO2 sequestration in the subsurface has been extensively studied and progressed as a direct tool to reduce CO2 emission. Commercial projects such as Sleipner, In Salah and Weyburn that inject more than one million tons of CO2 per year are operated actively as well as test projects such as Ketzin to study the behavior of CO2 and the monitoring techniques. Korea also began the CCS (CO2 capture and storage) project. One of the prospects for CO2 sequestration in Korea is the southwestern continental margin of Ulleung basin. To monitor the behavior of CO2 underground for the evaluation of stability and safety, several geophysical monitoring techniques should be applied. Among various geophysical monitoring techniques, seismic survey is considered as the most effective tool. To verify CO2 migration in the subsurface more effectively, seismic numerical simulation is an essential process. Furthermore, the efficiency of the seismic migration techniques should be investigated for various cases because numerical seismic simulation and migration test help us accurately interpret CO2 migration. In this study, we apply the reverse-time migration and Kirchhoff migration to synthetic seismic monitoring data generated for the simplified model based on the geological structures of Ulleung basin in Korea. Synthetic seismic monitoring data are generated for various cases of CO2 migration in the subsurface. From the seismic migration images, we can investigate CO2 diffusion patterns indirectly. From seismic monitoring simulation, it is noted that while the reverse-time migration generates clear subsurface images when subsurface structures are steeply dipping, Kirchhoff migration has an advantage in imaging horizontal-layered structures such as depositional sediments appearing in the continental shelf. The reverse-time migration and Kirchhoff migration present reliable subsurface images for the potential site characterized by stratigraphical traps. In case of vertical CO2 migration at injection point, the reverse time migration yields better images than Kirchhoff migration does. On the other hand, Kirchhoff migration images horizontal CO2 migration clearer than the reverse time migration does. From these results, we can conclude that the reverse-time migration and Kirchhoff migration can complement with each other to describe the behavior of CO2 in the subsurface. Acknowledgement This work was financially supported by the Brain Korea 21 project of Energy Systems Engineering, the "Development of Technology for CO2 Marine Geological Storage" program funded by the Ministry of Land, Transport and Maritime Affairs (MLTM) of Korea and the Korea CCS R&D Center (KCRC) grant funded by the Korea government (Ministry of Education, Science and Technology) (No. 2012-0008926).

Preliminary Results of Simulations and Field Investigations of the Performance of the WISDOM GPR of the ExoMars Rover

NASA Astrophysics Data System (ADS)

Ciarletti, V.; Corbel, C.; Cais, P.; Pltettemeier, D.; Hamran, S. E.; Oyan, M.; Clifford, S.; Reineix, A.

2009-04-01

WISDOM (Water Ice and Subsurface Deposit Observations on Mars) is a ground penetrat-ing radar (GPR) that was selected as one of three survey instruments on the ExoMars Rover Pasteur Payload. Its purpose is to characterize the nature of the shallow subsurface (including geological structure, electromagnetic properties, and potential hydrological state) and identify the most promising locations for investigation and sampling by the Rover's onboard drill - providing information down to a depth of 2 or 3 meters with a vertical resolution of a few centimeters (performance characteristics that will vary, depending on the local permittivity and conductivity of the subsurface). WISDOM is a polarimetric, step-frequency GPR operating over the frequency range of 0.5 - 3 GHz. The polarimetric capability of WISDOM is particularly useful for identifying and characterizing oriented structures like faults, fractures and stratigraphic interface roughness. To achieve this objective, special care has been dedicated to the design of the antenna system, which consists of a pair of Vivaldi antenna to conduct both co- and cross-polar measurements. WISDOM will perform its scientific investigations at each of the sites visited by the Rover and during the intervening traverses. During a traverse between two successive experiment cycles of the mission (drilling and sample analysis), WISDOM soundings will be performed to provide a coarse survey of the structure and nature of the underground and its large-scale variations. This information is required to understand the overall geological context and the properties of the subsurface. When a particular location has been selected for potential investigation by the drill, WISDOM will obtain subsurface profiles on a 2D grid, in order to synthesize a 3D map of subsurface soil characteristics and spatial variabil-ity. Full polarimetric soundings will be performed at 10 cm intervals along each parallel grid line, which will have a line-to-line spacing of 100cm. The typical grid-size for this 3D characterization is 5 m x 5 m. FDTD electromagntic simulations have been run on realistic Martian subsurface models to investigate the likely performances of the instrument once on Mars. In additiona, experi-mental field data was acquired during a 2008 mission to Svalabard, where the performance of the instrument in a permafrost environment was demonstrated. The results of that inves-tigation showed that WISDOM is capable of obtaining accurate data to depths in excess of 2-3 meters in ice-rich environments - successfully soundings through sediment layers, ice, and even into the underlying moraine, with sufficient spatial resolution to identify fine-scale layering within the intervening ice. Further results of these investigations will be presented at the meeting.

Plate Tectonics and Taiwan Orogeny based on TAIGER Experiments

NASA Astrophysics Data System (ADS)

Wu, F. T.; Kuochen, H.; McIntosh, K. D.

2014-12-01

Plate tectonics framework is usually complex in a collision zone, where continental lithosphere is involved. In the young Taiwan orogeny, with geologic understanding and large new geodetic and subsurface datasets now available an environment has been created for testing tectonic hypotheses regarding collision and orogeny. Against the background of the commonly accepted view of Taiwan as a southward propagating, self-similar 2-D orogen, a fully 3-D structure is envisaged. Along the whole length of the island the convergence of the Eurasian plate (EUP) the Philippine Sea plate (PSP) takes shape with different plate configurations. In northern Taiwan the convergence occurs with simultaneous collision of the oceanic PSP with continental EUP and the northward subduction of the PSP; in the south, EUP, in the guise of the South China Sea rifted Eurasian continent, subducts toward the east; in central Taiwan collision of oceanic PSP with continental EUP dominates. When relocated seismicity and focal mechanisms are superposed on subsurface P and Vp/Vs velocity images the configurations and the kinematics of the PSP and EUP collision and subduction become clear. While in northern Taiwan the subduction/collision explains well the high peaks and their dwindling (accompanied by crustal thinning) toward the north. In the south, mountains rise above the east-dipping EUP subduction zone as the Eurasian continental shelf veers toward the southwest, divergent from the trend of the Luzon Arc - calling into question the frequently cited arc-continent collision model of Taiwan orogeny. High velocity anomaly and Benioff seismicity coexist in the south. Going north toward Central Taiwan the high velocity anomaly persists for another 150 km or so, but it becomes seismically quiescent. Above the quiescent section the PSP and EUP collide to build the main part of the Central Range and its parallel neighbor the eastern Coastal Range. Key implications regarding orogeny include: 1) Significant petrological changes may accompany the crustal thickening, e.g., eclogitization, and delamination, 2) Rather than the detachment the exhumation of the metamorphic core of the Central Range is the main engine of the orogeny, and 3) The lithosphere has a complex rheological structure, indicated, in part, by the spatial distribution of seismicity.

Use of large-scale multi-configuration EMI measurements to characterize heterogeneous subsurface structures and their impact on crop productivity

NASA Astrophysics Data System (ADS)

Brogi, Cosimo; Huisman, Johan Alexander; Kaufmann, Manuela Sarah; von Hebel, Christian; van der Kruk, Jan; Vereecken, Harry

2017-04-01

Soil subsurface structures can play a key role in crop performance, especially during water stress periods. Geophysical techniques like electromagnetic induction EMI have been shown to be able of providing information about dominant shallow subsurface features. However, previous work with EMI has typically not reached beyond the field scale. The objective of this study is to use large-scale multi-configuration EMI to characterize patterns of soil structural organization (layering and texture) and the associated impact on crop vegetation at the km2 scale. For this, we carried out an intensive measurement campaign and collected high spatial resolution multi-configuration EMI data on an agricultural area of approx. 1 km2 (102 ha) near Selhausen (North Rhine-Westphalia, Germany) with a maximum depth of investigation of around 2.5 m. We measured using two EMI instruments simultaneously with a total of nine coil configurations. The instruments were placed inside polyethylene sleds that were pulled by an all-terrain-vehicle along parallel lines with a spacing of 2 to 2.5 m. The driving speed was between 5 and 7 km h-1 and we used a 0.2 Hz sampling frequency to obtain an in-line resolution of approximately 0.3 m. The survey area consists of almost 50 different fields managed in different way. The EMI measurements were collected between April and December 2016 within a few days after the harvest of each field. After data acquisition, EMI data were automatically filtered, temperature corrected, and interpolated onto a common grid. The resulting EMI maps allowed us to identify three main areas with different subsurface heterogeneities. The differences between these areas are likely related to the late quaternary geological history (Pleistocene and Holocene) of the area that resulted in spatially variable soil texture and layering, which has a strong impact on spatio-temporal soil water content variability. The high resolution surveys also allowed us to identify small scale geomorphological structures as well as anthropogenic activities such as soil management and drainage networks carried out in the last 150 years. To identify areas with similar subsurface structures with high spatial resolution, we applied multiband image classification using the nine coil configurations as bands of a single image. We compared both supervised and unsupervised classification and obtained promising preliminary results showing a good degree of conformity between EMI supervised classification maps and observed patterns in plant productivity.

Investigation of the influence of groundwater advection on energy extraction rates for sustainable borehole heat exchanger operation

NASA Astrophysics Data System (ADS)

Schelenz, Sophie; Dietrich, Peter; Vienken, Thomas

2016-04-01

A sustainable thermal exploitation of the shallow subsurface requires a precise understanding of all relevant heat transport processes. Currently, planning practice of shallow geothermal systems (especially for systems < 30 kW) focuses on conductive heat transport as the main energy source while the impact of groundwater flow as the driver for advective heat transport is neglected or strongly simplified. The presented study proves that those simplifications of complex geological and hydrogeological subsurface characteristics are insufficient for a precise evaluation of site-specific energy extraction rates. Based on synthetic model scenarios with varying subsurface conditions (groundwater flow velocity and aquifer thickness) the impact of advection on induced long term temperature changes in 5 and 10 m distance of the borehole heat exchanger is presented. Extending known investigations, this study enhances the evaluation of shallow geothermal energy extraction rates by considering conductive and advective heat transport under varying aquifer thicknesses. Further, it evaluates the impact of advection on installation lengths of the borehole heat exchanger to optimize the initial financial investment. Finally, an evaluation approach is presented that classifies relevant heat transport processes according to their Péclet number to enable a first quantitative assessment of the subsurface energy regime and recommend further investigation and planning procedures.

Subsurface multidisciplinary research results at ICTJA-CSIC downhole lab and test site

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Crespo, Jose; Salvany, Josep Maria; Teixidó, Teresa

2017-04-01

Two scientific boreholes, Almera-1 and Almera-2 were drilled in the Barcelona University campus area in 2011. The main purpose for this drilling was to create a new geophysical logging and downhole monitoring research facility and infrastructure. We present results obtained in the frame of multidisciplinary studies and experiments carried out since 2011 at the ICTJA "Borehole Geophysical Logging Lab - Scientific Boreholes Almera" downhole lab facilities. First results obtained from the scientific drilling, coring and logging allowed us to characterize the urban subsurface geology and hydrology adjacent to the Institute of Earth Sciences Jaume Almera (ICTJA-CSIC) in Barcelona. The subsurface geology and structural picture has been completed with recent geophysical studies and monitoring results. The upper section of Almera-1 214m deep hole was cased with PVC after drilling and after the logging operations. An open hole interval was left from 112m to TD (Paleozoic section). Almera-2 drilling reached 46m and was cased also with PVC to 44m. Since completion of the drilling in 2011, both Almera-1 and Almera-2 have been extensively used for research purposes, tests, training, hydrological and geophysical monitoring. A complete set of geophysical logging measurements and borehole oriented images were acquired in open hole mode of the entire Almera-1 section. Open hole measurements included acoustic and optical imaging, spectral natural gamma ray, full wave acoustic logging, magnetic susceptibility, hydrochemical-temperature logs and fluid sampling. Through casing (PVC casing) measurements included spectral gamma ray logging, full wave sonic and acoustic televiewer. A Quaternary to Paleozoic section was characterized based on the geophysical logging and borehole images interpretation and also on the complete set of (wireline) cores of the entire section. Sample availability was intended for geological macro and micro-facies detailed characterization, mineralogical and petrophysical tests and analyses. The interpretation of the geophysical logging data and borehole oriented images, and core data allowed us to define the stratigraphy, structures and petrophysical properties in the subsurface. Quaternary sediments overlie unconformably weathered, deformed and partially metamorphosed Paleozoic rocks. A gap of the Tertiary rocks at the drillsite was detected. Structures at intensely fractured and faulted sections were measured and have yielded valuable data to understand the subsurface geology, hydrology and geological evolution in that area. Logging, borehole imaging and monitoring carried out in the scientific boreholes Almera-1 and Almera-2 has allowed also to identify three preferential groundwater flow paths in the subsurface. Geophysical logging data combined with groundwater monitoring allowed us to identify three zones of high permeability in the subsurface. Logging data combined with core analysis were used to characterize the aquifers lithology and their respective petrophysical properties. We also analyzed the aquifer dynamics and potential relationships between the variations in groundwater levels and the rainfalls by comparing the groundwater monitoring results and the rainfall. A seismic survey was carried out to outline the geological structures beyond Almera-1 borehole, a vertical reverse pseudo-3D (2.5D) seismic tomography experiment. The results allowed us to define the geological structure beyond the borehole wall and also a correlation between the different geological units in the borehole and their geometry and spatial geophysical and seismic image.

Isolated molecular dopants in pentacene observed by scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Ha, Sieu D.; Kahn, Antoine

2009-11-01

Doping is essential to the control of electronic structure and conductivity of semiconductor materials. Whereas doping of inorganic semiconductors is well established, doping of organic molecular semiconductors is still relatively poorly understood. Using scanning tunneling microscopy, we investigate, at the molecular scale, surface and subsurface tetrafluoro-tetracyanoquinodimethane p -dopants in the prototypical molecular semiconductor pentacene. Surface dopants diffuse to pentacene vacancies and appear as negatively charged centers, consistent with the standard picture of an ionized acceptor. Subsurface dopants, however, have the effect of a positive charge, evidence that the donated hole is localized by the parent acceptor counterion, in contrast to the model of doping in inorganic semiconductors. Scanning tunneling spectroscopy shows that the electron potential energy is locally lowered near a subsurface dopant feature, in agreement with the localized hole model.

Sorting Out the Ocean Crust Deep Biosphere with Single Cell Omics Approaches

NASA Astrophysics Data System (ADS)

Orcutt, B.; D'Angelo, T.; Goordial, J.; Jones, R. M.; Carr, S. A.

2017-12-01

Although oceanic crust comprises a large habitat for subsurface life, the structure, function, and dynamics of microbial communities living on rocks in the subsurface are poorly understood. Single cell level approaches can overcome limitations of low biomass in subsurface systems. Coupled with incubation experiments with amino acid orthologs, single cell level sorting can reveal high resolution information about identity, functional potential, and growth. Leveraging collaboration with the Single Cell Genomics Center and the Facility for Aquatic Cytometry at Bigelow Laboratory, we present recent results from single cell level sorting and -omics sequencing from several crustal environments, including the Atlantis Massif and the Juan de Fuca Ridge flank. We will also highlight new experiments conducted with samples recovered from the flank of the Mid-Atlantic Ridge.

Integrating Geohydrological Models In ATES-Systems Control

NASA Astrophysics Data System (ADS)

Bloemendal, Martin

2015-04-01

1) Purpose. Accomplish optimal and sustainable use of subsurface for Aquifer Thermal Energy Storage (ATES). 2) Scope. A heat pump in combination with an ATES system can efficiently and sustainably provide heating and cooling for user comfort within buildings. ATES systems are popular in moderate climate in which ATES systems are exploited as they are able to save primary energy. While storing warm and cold groundwater, ATES systems occupy a significant amount of the subsurface space, making that the space in the aquifers below cities is becoming scarce [1]. With the rapid growth of the number of ATES systems, the use of the subsurface intensifies, which raises additional questions regarding its sustainability and the long term profitability of the individual systems. In practice considerable difficulties regarding A) the performance of these installations and B) optimal and sustainable use of the subsurface are met. 3) Approach. Recently it was confirmed [2] that ATES systems can be placed closer to each other with limited effect on their energy efficiency. By placing them closer together we introduce the risk of a tragedy of the commons [3]. Therefore it is of importance to know where the warm and cold zones are over time and enable ATES-controllers to use the subsurface optimal and sustainably. From the field of multi agent systems and complex adaptive systems we use approaches and techniques to make an operation and control system that enables to adapt their control not only based on current demand, but also on current aquifer status and expected future demand. We are developing a numerical groundwater model structure which is fed with operational data of different ATES-systems. While doing this we run into challenges and opportunities like; spatial and temporal scale issues, sustaining the storage with balancing thermal storage and extraction at area level, dynamics and relation between hydrological and thermal influence and consequences for spreading of contaminants, using thermal energy storage for "peak-shaving" of wind/solar power production etc.. I will address the following two topics; - Balancing of stored heating and cooling capacity. To sustain an ATES-system heating and cooling capacity storage must more or less balance. Buildings often do not have a similar heating and cooling demand. Placing ATES-well closer to each other offers the opportunity to exchange energy between different buildings in the subsurface to balance heating and cooling capacity. To be able to do so, thorough understanding of the interaction between thermal influence area resulting from highly dynamic and uncertain energy demand from buildings is required. - The hydrological influence area of ATES wells is much bigger than the thermal influence area. Placing wells closer to each other therefor has a significant effect on the mixing of water and spreading of contaminants (which are often present in shallow aquifers under (old) city centers). We use both analytical and numerical approaches to gain insight in patterns of thermal and contaminant spreading and to find solutions in managing these effects. 4) Results and conclusions The subsurface is of crucial importance for intended energy savings. A control system working towards a global optimum for both the subsurface and buildings, instead of a local optimum for an individual building and local ATES will increase the overall efficiency. What is needed for that is insight in the spatial temperature distribution in the subsurface, in combination with adaptive and robust operational rules. We want to prove that a groundwater model simulating active ATES-systems can provide insight in the subsurface temperature distribution to adjust their control strategy in accordance with up-to-date information. Step by step we are solving the problems on this path, I would like to share and discuss my results, solutions and challenges. References [1] Bloemendal, M., Olsthoorn, T., Boons, F., How to achieve optimal and sustainable use of the subsurface for Aquifer Thermal Energy Storage, Energy Policy 66(2014) 104-114 [2] Sommer, W., Valstar, J., Leusbrock, I., Grotenhuis, T., Rijnaarts, H., Optimization and spatial pattern of large-scale aquifer thermal energy storage, Applied Energy 137 (2015) 322-337 [3] Hardin, G., The tragedy of the commons, Science162 (168) 12-13.

Drilling subsurface wellbores with cutting structures

DOEpatents

Mansure, Arthur James; Guimerans, Rosalvina Ramona

2010-11-30

A system for forming a wellbore includes a drill tubular. A drill bit is coupled to the drill tubular. One or more cutting structures are coupled to the drill tubular above the drill bit. The cutting structures remove at least a portion of formation that extends into the wellbore formed by the drill bit.

A subsurface drip irrigation system for weighing lysimetry

USDA-ARS?s Scientific Manuscript database

Large, precision weighing lysimeters can have accuracies as good as 0.04 mm equivalent depth of water, adequate for hourly and even half-hourly determinations of evapotranspiration (ET) rate from crops. Such data are important for testing and improving simulation models of the complex interactions o...

EVALUATION OF GEOPHYSICAL METHODS FOR THE DETECTION OF SUBSURFACE TETRACHLOROETHYLENE IN CONTROLLED SPILL EXPERIMENTS

EPA Science Inventory

This paper presents some of the results of five of the techniques: cross borehole complex resistivity (CR) also referred to as spectral induced polarization (SIP), cross borehole high resolution seismic (HRS), borehole self potential (SP), surface ground penetration radar (GPR), ...

Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles.

PubMed

Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius; Ham, Hyung Chul

2015-01-21

The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt3M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.

Vel-IO 3D: A tool for 3D velocity model construction, optimization and time-depth conversion in 3D geological modeling workflow

NASA Astrophysics Data System (ADS)

Maesano, Francesco E.; D'Ambrogi, Chiara

2017-02-01

We present Vel-IO 3D, a tool for 3D velocity model creation and time-depth conversion, as part of a workflow for 3D model building. The workflow addresses the management of large subsurface dataset, mainly seismic lines and well logs, and the construction of a 3D velocity model able to describe the variation of the velocity parameters related to strong facies and thickness variability and to high structural complexity. Although it is applicable in many geological contexts (e.g. foreland basins, large intermountain basins), it is particularly suitable in wide flat regions, where subsurface structures have no surface expression. The Vel-IO 3D tool is composed by three scripts, written in Python 2.7.11, that automate i) the 3D instantaneous velocity model building, ii) the velocity model optimization, iii) the time-depth conversion. They determine a 3D geological model that is consistent with the primary geological constraints (e.g. depth of the markers on wells). The proposed workflow and the Vel-IO 3D tool have been tested, during the EU funded Project GeoMol, by the construction of the 3D geological model of a flat region, 5700 km2 in area, located in the central part of the Po Plain. The final 3D model showed the efficiency of the workflow and Vel-IO 3D tool in the management of large amount of data both in time and depth domain. A 4 layer-cake velocity model has been applied to a several thousand (5000-13,000 m) thick succession, with 15 horizons from Triassic up to Pleistocene, complicated by a Mesozoic extensional tectonics and by buried thrusts related to Southern Alps and Northern Apennines.

Validation of an In-Water, Tower-Shading Correction Scheme

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Doyle, John P.; Zibordi, Giuseppe; vanderLinde, Dirk

2003-01-01

Large offshore structures used for the deployment of optical instruments can significantly perturb the intensity of the light field surrounding the optical measurement point, where different portions of the visible spectrum are subject to different shadowing effects. These effects degrade the quality of the acquired optical data and can reduce the accuracy of several derived quantities, such as those obtained by applying bio-optical algorithms directly to the shadow-perturbed data. As a result, optical remote sensing calibration and validation studies can be impaired if shadowing artifacts are not fully accounted for. In this work, the general in-water shadowing problem is examined for a particular case study. Backward Monte Carlo (MC) radiative transfer computations- performed in a vertically stratified, horizontally inhomogeneous, and realistic ocean-atmosphere system are shown to accurately simulate the shadow-induced relative percent errors affecting the radiance and irradiance data profiles acquired close to an oceanographic tower. Multiparameter optical data processing has provided adequate representation of experimental uncertainties allowing consistent comparison with simulations. The more detailed simulations at the subsurface depth appear to be essentially equivalent to those obtained assuming a simplified ocean-atmosphere system, except in highly stratified waters. MC computations performed in the simplified system can be assumed, therefore, to accurately simulate the optical measurements conducted under more complex sampling conditions (i.e., within waters presenting moderate stratification at most). A previously reported correction scheme, based on the simplified MC simulations, and developed for subsurface shadow-removal processing of in-water optical data taken close to the investigated oceanographic tower, is then validated adequately under most experimental conditions. It appears feasible to generalize the present tower-specific approach to solve other optical sensor shadowing problems pertaining to differently shaped deployment platforms, and also including surrounding structures and instrument casings.

Influence of spatial and temporal variability of subsurface soil moisture and temperature on vapour intrusion

NASA Astrophysics Data System (ADS)

Bekele, Dawit N.; Naidu, Ravi; Chadalavada, Sreenivasulu

2014-05-01

A comprehensive field study was conducted at a site contaminated with chlorinated solvents, mainly trichloroethylene (TCE), to investigate the influence of subsurface soil moisture and temperature on vapour intrusion (VI) into built structures. Existing approaches to predict the risk of VI intrusion into buildings assume homogeneous or discrete layers in the vadose zone through which TCE migrates from an underlying source zone. In reality, the subsurface of the majority of contaminated sites will be subject to significant variations in moisture and temperature. Detailed site-specific data were measured contemporaneously to evaluate the impact of spatial and temporal variability of subsurface soil properties on VI exposure assessment. The results revealed that indoor air vapour concentrations would be affected by spatial and temporal variability of subsurface soil moisture and temperature. The monthly monitoring of soil-gas concentrations over a period of one year at a depth of 3 m across the study site demonstrated significant variation in TCE vapour concentrations, which ranged from 480 to 629,308 μg/m3. Soil-gas wells at 1 m depth exhibited high seasonal variability in TCE vapour concentrations with a coefficient of variation 1.02 in comparison with values of 0.88 and 0.74 in 2 m and 3 m wells, respectively. Contour plots of the soil-gas TCE plume during wet and dry seasons showed that the plume moved across the site, hence locations of soil-gas monitoring wells for human risk assessment is a site specific decision. Subsurface soil-gas vapour plume characterisation at the study site demonstrates that assessment for VI is greatly influenced by subsurface soil properties such as temperature and moisture that fluctuate with the seasons of the year.

Multi-scale hierarchy of Chelydra serpentina: microstructure and mechanical properties of turtle shell.

PubMed

Balani, Kantesh; Patel, Riken R; Keshri, Anup K; Lahiri, Debrupa; Agarwal, Arvind

2011-10-01

Carapace, the protective shell of a freshwater snapping turtle, Chelydra serpentina, shields them from ferocious attacks of their predators while maintaining light-weight and agility for a swim. The microstructure and mechanical properties of the turtle shell are very appealing to materials scientists and engineers for bio-mimicking, to obtain a multi-functional surface. In this study, we have elucidated the complex microstructure of a dry Chelydra serpentina's shell which is very similar to a multi-layered composite structure. The microstructure of a turtle shell's carapace elicits a sandwich structure of waxy top surface with a harder sub-surface layer serving as a shielding structure, followed by a lamellar carbonaceous layer serving as shock absorber, and the inner porous matrix serves as a load-bearing scaffold while acting as reservoir of retaining water and nutrients. The mechanical properties (elastic modulus and hardness) of various layers obtained via nanoindentation corroborate well with the functionality of each layer. Elastic modulus ranged between 0.47 and 22.15 GPa whereas hardness varied between 53.7 and 522.2 MPa depending on the microstructure of the carapace layer. Consequently, the modulus of each layer was represented into object oriented finite element (OOF2) modeling towards extracting the overall effective modulus of elasticity (~4.75 GPa) of a turtle's carapace. Stress distribution of complex layered structure was elicited with an applied strain of 1% in order to understand the load sharing of various composite layers in the turtle's carapace. Copyright © 2011 Elsevier Ltd. All rights reserved.

Solving subsurface structural problems using a computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witte, D.M.

1987-02-01

Until recently, the solution of subsurface structural problems has required a combination of graphical construction, trigonometry, time, and patience. Recent advances in software available for both mainframe and microcomputers now reduce the time and potential error of these calculations by an order of magnitude. Software for analysis of deviated wells, three point problems, apparent dip, apparent thickness, and the intersection of two planes, as well as the plotting and interpretation of these data can be used to allow timely and accurate exploration or operational decisions. The available computer software provides a set of utilities, or tools, rather than a comprehensive,more » intelligent system. The burden for selection of appropriate techniques, computation methods, and interpretations still lies with the explorationist user.« less

Seismic images of a tectonic subdivision of the Greenville Orogen beneath lakes Ontario and Erie

USGS Publications Warehouse

Forsyth, D. A.; Milkereit, B.; Davidson, A.; Hanmer, S.; Hutchinson, Deborah R.; Hinze, W. J.; Mereu, R.F.

1994-01-01

New seismic data from marine air-gun and Vibroseis profiles in Lake Ontario and Lake Erie provide images of subhorizontal Phanerozoic sediments underlain by a remarkable series of easterly dipping reflections that extends from the crystalline basement to the lower crust. These reflections are interpreted as structural features of crustal-scale subdivisions within the Grenville Orogen. Broadly deformed, imbricated, and overlapping thrust sheets within the western Central Metasedimentary Belt are succeeded to the west by a complex zone of easterly dipping, apparent thrust faults that are interpreted as a southwest subsurface extension of the boundary zone between the Central Metasedimentary Belt and the Central Gneiss Belt. The interpreted Central Metasedimentary Belt boundary zone has a characteristic magnetic anomaly that provides a link from the adjacent ends of lakes Ontario and Erie to structures exposed 150 km to the north. Less reflective, west-dipping events are interpreted as structures within the eastern Central Gneiss Belt. The seismic interpretation augments current tectonic models that suggest the exposed ductile structures formed at depth as a result of crustal shortening along northwest-verging thrust faults. Relatively shallow reflections across the boundary region suggest local, Late Proterozoic extensional troughs containing post-Grenville sediments, preserved possibly as a result of pre-Paleozoic reactivation of basement structures.

Restructuring and Hydrogen Evolution on Pt Nanoparticle† †Electronic supplementary information (ESI) available: Discussions on the structures of Pt clusters and the stability of the subsurface H atoms in Pt cluster, TS structure of H–H coupling on {111} facets of Pt44H80, XYZ coordinate of Pt44 and Pt44H80. Movie of structure evolution at Pt44H50 See DOI: 10.1039/c4sc02806f Click here for additional data file. Click here for additional data file.

PubMed Central

Wei, Guang-Feng

2015-01-01

The restructuring of nanoparticles at the in situ condition is a common but complex phenomenon in nanoscience. Here, we present the first systematic survey on the structure dynamics and its catalytic consequence for hydrogen evolution reaction (HER) on Pt nanoparticles, as represented by a magic number Pt44 octahedron (∼1 nm size). Using a first principles calculation based global structure search method, we stepwise follow the significant nanoparticle restructuring under HER conditions as driven by thermodynamics to expose {100} facets, and reveal the consequent large activity enhancement due to the marked increase of the concentration of the active site, being identified to be apex atoms. The enhanced kinetics is thus a “byproduct” of the thermodynamical restructuring. Based on the results, the best Pt catalyst for HER is predicted to be ultrasmall Pt particles without core atoms, a size below ∼20 atoms. PMID:29560237

A Mobile Acoustic Subsurface Sensing (MASS) System for Rapid Roadway Assessment

PubMed Central

Lu, Yifeng; Zhang, Yi; Cao, Yinghong; McDaniel, J. Gregory; Wang, Ming L.

2013-01-01

Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW) has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test. PMID:23698266

How does subsurface retain and release stored water? An explicit estimation of young water fraction and mean transit time

NASA Astrophysics Data System (ADS)

Ameli, Ali; McDonnell, Jeffrey; Laudon, Hjalmar; Bishop, Kevin

2017-04-01

The stable isotopes of water have served science well as hydrological tracers which have demonstrated that there is often a large component of "old" water in stream runoff. It has been more problematic to define the full transit time distribution of that stream water. Non-linear mixing of previous precipitation signals that is stored for extended periods and slowly travel through the subsurface before reaching the stream results in a large range of possible transit times. It difficult to find tracers can represent this, especially if all that one has is data on the precipitation input and the stream runoff. In this paper, we explicitly characterize this "old water" displacement using a novel quasi-steady physically-based flow and transport model in the well-studied S-Transect hillslope in Sweden where the concentration of hydrological tracers in the subsurface and stream has been measured. We explore how subsurface conductivity profile impacts the characteristics of old water displacement, and then test these scenarios against the observed dynamics of conservative hydrological tracers in both the stream and subsurface. This work explores the efficiency of convolution-based approaches in the estimation of stream "young water" fraction and time-variant mean transit times. We also suggest how celerity and velocity differ with landscape structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoak, T.E.; Decker, A.D.

Mesaverde Group reservoirs in the Piceance Basin, Western Colorado contain a large reservoir base. Attempts to exploit this resource base are stymied by low permeability reservoir conditions. The presence of abundant natural fracture systems throughout this basin, however, does permit economic production. Substantial production is associated with fractured reservoirs in Divide Creek, Piceance Creek, Wolf Creek, White River Dome, Plateau, Shire Gulch, Grand Valley, Parachute and Rulison fields. Successful Piceance Basin gas production requires detailed information about fracture networks and subsurface gas and water distribution in an overall gas-centered basin geometry. Assessment of these three parameters requires an integrated basinmore » analysis incorporating conventional subsurface geology, seismic data, remote sensing imagery analysis, and an analysis of regional tectonics. To delineate the gas-centered basin geometry in the Piceance Basin, a regional cross-section spanning the basin was constructed using hydrocarbon and gamma radiation logs. The resultant hybrid logs were used for stratigraphic correlations in addition to outlining the trans-basin gas-saturated conditions. The magnitude of both pressure gradients (paludal and marine intervals) is greater than can be generated by a hydrodynamic model. To investigate the relationships between structure and production, detailed mapping of the basin (top of the Iles Formation) was used to define subtle subsurface structures that control fractured reservoir development. The most productive fields in the basin possess fractured reservoirs. Detailed studies in the Grand Valley-Parachute-Rulison and Shire Gulch-Plateau fields indicate that zones of maximum structural flexure on kilometer-scale structural features are directly related to areas of enhanced production.« less

Testing & Validating: 3D Seismic Travel Time Tomography (Detailed Shallow Subsurface Imaging)

NASA Astrophysics Data System (ADS)

Marti, David; Marzan, Ignacio; Alvarez-Marron, Joaquina; Carbonell, Ramon

2016-04-01

A detailed full 3 dimensional P wave seismic velocity model was constrained by a high-resolution seismic tomography experiment. A regular and dense grid of shots and receivers was use to image a 500x500x200 m volume of the shallow subsurface. 10 GEODE's resulting in a 240 channels recording system and a 250 kg weight drop were used for the acquisition. The recording geometry consisted in 10x20m geophone grid spacing, and a 20x20 m stagered source spacing. A total of 1200 receivers and 676 source points. The study area is located within the Iberian Meseta, in Villar de Cañas (Cuenca, Spain). The lithological/geological target consisted in a Neogen sedimentary sequence formed from bottom to top by a transition from gyspum to silstones. The main objectives consisted in resolving the underground structure: contacts/discontinuities; constrain the 3D geometry of the lithology (possible cavities, faults/fractures). These targets were achieved by mapping the 3D distribution of the physical properties (P-wave velocity). The regularly space dense acquisition grid forced to acquire the survey in different stages and with a variety of weather conditions. Therefore, a careful quality control was required. More than a half million first arrivals were inverted to provide a 3D Vp velocity model that reached depths of 120 m in the areas with the highest ray coverage. An extended borehole campaign, that included borehole geophysical measurements in some wells provided unique tight constraints on the lithology an a validation scheme for the tomographic results. The final image reveals a laterally variable structure consisting of four different lithological units. In this methodological validation test travel-time tomography features a high capacity of imaging in detail the lithological contrasts for complex structures located at very shallow depths.

Internal fracture heterogeneity in discrete fracture network modelling: Effect of correlation length and textures with connected and disconnected permeability field

NASA Astrophysics Data System (ADS)

Frampton, A.; Hyman, J.; Zou, L.

2017-12-01

Analysing flow and transport in sparsely fractured media is important for understanding how crystalline bedrock environments function as barriers to transport of contaminants, with important applications towards subsurface repositories for storage of spent nuclear fuel. Crystalline bedrocks are particularly favourable due to their geological stability, low advective flow and strong hydrogeochemical retention properties, which can delay transport of radionuclides, allowing decay to limit release to the biosphere. There are however many challenges involved in quantifying and modelling subsurface flow and transport in fractured media, largely due to geological complexity and heterogeneity, where the interplay between advective and dispersive flow strongly impacts both inert and reactive transport. A key to modelling transport in a Lagrangian framework involves quantifying pathway travel times and the hydrodynamic control of retention, and both these quantities strongly depend on heterogeneity of the fracture network at different scales. In this contribution, we present recent analysis of flow and transport considering fracture networks with single-fracture heterogeneity described by different multivariate normal distributions. A coherent triad of fields with identical correlation length and variance are created but which greatly differ in structure, corresponding to textures with well-connected low, medium and high permeability structures. Through numerical modelling of multiple scales in a stochastic setting we quantify the relative impact of texture type and correlation length against network topological measures, and identify key thresholds for cases where flow dispersion is controlled by single-fracture heterogeneity versus network-scale heterogeneity. This is achieved by using a recently developed novel numerical discrete fracture network model. Furthermore, we highlight enhanced flow channelling for cases where correlation structure continues across intersections in a network, and discuss application to realistic fracture networks using field data of sparsely fractured crystalline rock from the Swedish candidate repository site for spent nuclear fuel.

Joint-inversion of gravity data and cosmic ray muon flux to detect shallow subsurface density structure beneath volcanoes: Testing the method at a well-characterized site

NASA Astrophysics Data System (ADS)

Roy, M.; Lewis, M.; George, N. K.; Johnson, A.; Dichter, M.; Rowe, C. A.; Guardincerri, E.

2016-12-01

The joint-inversion of gravity data and cosmic ray muon flux measurements has been utilized by a number of groups to image subsurface density structure in a variety of settings, including volcanic edifices. Cosmic ray muons are variably-attenuated depending upon the density structure of the material they traverse, so measuring muon flux through a region of interest provides an independent constraint on the density structure. Previous theoretical studies have argued that the primary advantage of combining gravity and muon data is enhanced resolution in regions not sampled by crossing muon trajectories, e.g. in sensing deeper structure or structure adjacent to the region sampled by muons. We test these ideas by investigating the ability of gravity data alone and the joint-inversion of gravity and muon flux to image subsurface density structure, including voids, in a well-characterized field location. Our study area is a tunnel vault located at the Los Alamos National Laboratory within Quaternary ash-flow tuffs on the Pajarito Plateau, flanking the Jemez Volcano in New Mexico. The regional geology of the area is well-characterized (with density measurements in nearby wells) and the geometry of the tunnel and the surrounding terrain is known. Gravity measurements were made using a Lacoste and Romberg D meter and the muon detector has a conical acceptance region of 45 degrees from the vertical and track resolution of several milliradians. We obtain individual and joint resolution kernels for gravity and muon flux specific to our experimental design and plan to combine measurements of gravity and muon flux both within and above the tunnel to infer density structure. We plan to compare our inferred density structure against the expected densities from the known regional hydro-geologic framework.

Variable Grid Traveltime Tomography for Near-surface Seismic Imaging

NASA Astrophysics Data System (ADS)

Cai, A.; Zhang, J.

2017-12-01

We present a new algorithm of traveltime tomography for imaging the subsurface with automated variable grids upon geological structures. The nonlinear traveltime tomography along with Tikhonov regularization using conjugate gradient method is a conventional method for near surface imaging. However, model regularization for any regular and even grids assumes uniform resolution. From geophysical point of view, long-wavelength and large scale structures can be reliably resolved, the details along geological boundaries are difficult to resolve. Therefore, we solve a traveltime tomography problem that automatically identifies large scale structures and aggregates grids within the structures for inversion. As a result, the number of velocity unknowns is reduced significantly, and inversion intends to resolve small-scale structures or the boundaries of large-scale structures. The approach is demonstrated by tests on both synthetic and field data. One synthetic model is a buried basalt model with one horizontal layer. Using the variable grid traveltime tomography, the resulted model is more accurate in top layer velocity, and basalt blocks, and leading to a less number of grids. The field data was collected in an oil field in China. The survey was performed in an area where the subsurface structures were predominantly layered. The data set includes 476 shots with a 10 meter spacing and 1735 receivers with a 10 meter spacing. The first-arrival traveltime of the seismogram is picked for tomography. The reciprocal errors of most shots are between 2ms and 6ms. The normal tomography results in fluctuations in layers and some artifacts in the velocity model. In comparison, the implementation of new method with proper threshold provides blocky model with resolved flat layer and less artifacts. Besides, the number of grids reduces from 205,656 to 4,930 and the inversion produces higher resolution due to less unknowns and relatively fine grids in small structures. The variable grid traveltime tomography provides an alternative imaging solution for blocky structures in the subsurface and builds a good starting model for waveform inversion and statics.

Time-frequency analysis of GPR data to investigate the damage of monumental buildings

NASA Astrophysics Data System (ADS)

Leucci, Giovanni; Masini, Nicola; Persico, Raffaele

2012-08-01

The presence of particular microclimatic conditions inside monumental buildings is responsible for bio-deterioration processes. In many cases, efflorescence and moulds are visible on the facades of several monuments of historical importance. In many other cases, the effects of decay processes are not visible, thus making difficult the diagnosis and the consequent setup of effective rehabilitation and preservation interventions, especially in the presence of a complex geometry and/or a large variability of construction materials. In such cases, a valuable contribution could be provided by geophysical methods (such as electrical resistivity, electromagnetic conductivity, ground-penetrating radar (GPR), etc), which have been proved to be successful tools for sub-surface investigation and characterization of historical buildings. In old monumental buildings, the masonry structures frequently exhibit cracks, voids, detachments and high moisture contrasts that can give rise to reflection events in radar signals. However, the complexity of the geometry and the structural heterogeneity that characterize these old structures often make the GPR results difficult to analyse and interpret. In particular, the spatial variation in GPR signal attenuation can provide important information about the electrical properties of the investigated materials that, in turn, can be used to assess the physical parameters associated with damage. In this paper, we propose an approach that analyses the data in the form of ‘frequency maps’ to evidence absorption losses probably linked to higher moisture content. Two real case histories back up the proposed method.

Study of hydrothermal channels based on near-bottom magnetic prospecting: Application to Longqi hydrothermal area

NASA Astrophysics Data System (ADS)

Tao, W.; Tao, C.; Li, H.; Zhaocai, W.; Jinhui, Z.; Qinzhu, C.; Shili, L.

2014-12-01

Mid-ocean ridges, largely present far from the continental plates, are characterized by complex geological structures and numerous hydrothermal systems with complex controlling factors. Exploring seafloor sulfide resources for industrial and scientific applications is a challenge. With the advent of geophysical surveys for seabed investigation, near-bottom magnetic prospecting, which yields shallow geological structure, is an efficient method for investigating active and inactive hydrothermal fields and for researching the structure of hydrothermal systems (Tivey et al., 1993, 1996；German et al., 2008). We collected near-bottom magnetic data in the Longqi hydrothermal area, located in the southwest Indian ridge (49.6° E; Zhu et al., 2010; Tao et al., 2014), using the autonomous benthic explorer, an autonomous underwater vehicle, during the second leg of the Chinese cruise DY115-19 on board R/V DaYangYiHao. Based on the results of the intensity of the spatial differential vector method (Seaman et al., 1993), we outline the hydrothermal alternation zone. By building models, we subsequently infer a fault along the discovered hydrothermal vents; this fault line may be connected to a detachment fault (Zhao et al., 2013). In addition, we discuss the channels of the hydrothermal circulation system (Figure 1), and presume that heat was conducted to the sea subsurface by the detachment fault; the aqueous fluid that infiltrated the fault is heated and conveyed to the seafloor, promoting the circulation of the hydrothermal system.

Habitat Inspection Scanner, Bio-Structure Scanner, and In Situ Sub-Surface Composition Sensor

NASA Technical Reports Server (NTRS)

VanSteenberg, Michael

2004-01-01

The extension of dielectric and inductive spectroscopy into in situ observations represents a significant exploration-enabling tool. This technology can be widely applied from microscopic to macroscopic. Dielectrometry and inductometry can measure sub-surface composition and its distribution. The primary environment that we cannot easily explored is the sub-surface of solid bodies. Weather as part of our equipment that we bring with us, or the locations we are exploring. These fundamental questions lie at the core of the exploration Initiative. To answer them we must use a whole host of complimentary tools including those that allow us to practically examine the sub-surface environment. A nondestructive approach offers significant advantages for both the initial identification of likely samples but also the monitoring of ecosystems and crew health. These include materials characterization, nondestructive inspection, and process quality control, damage monitoring, and hidden object detection and identification. The identification of natural resources such as water on the Moon or Mars is of great importance to the utilization of local resource in the support of human exploration crews. On the macroscopic scale, the understanding of what resources are available and how they are distributed is of primary importance to their productive utilization. Even if initial explorations do not require the use of local resources to succeed, eventual settlement and commercial development will. The routine examination of the structural integrity (micro cracks, leaks) of hi.inafi habitats in harsh envkmments ww!d also be enabled.

Remineralisation of enamel white spot lesions pre-treated with chitosan in the presence of salivary pellicle.

PubMed

Zhang, Jing; Lynch, Richard J M; Watson, Timothy F; Banerjee, Avijit

2018-05-01

To investigate the remineralisation of chitosan pre-treated enamel white spot lesions (WSLs) by bioglass in the presence of the pellicle layer. 50 artificial enamel white spot lesions were created by acidic gel. Two lesions were used to investigate the formation of the pellicle layer by treating with human whole saliva for 3 min. 48 lesions were assigned to 6 experimental groups (n = 8): (1) bioactive glass slurry, (2) bioactive glass containing polyacrylic acid (BG + PAA) slurry, (3) chitosan pre-treated WSLs with BG slurry (CS-BG), (4) chitosan pre-treated WSLs with BG + PAA slurry (CS-BG + PAA), (5) "standard" remineralisation solution (RS) and (6) de-ionised water (negative control, NC). Remineralisation was carried out using a pH-cycling model for 7 days. Before each treatment using remineralising agents, 3-min pellicle was formed on lesions' surfaces. Mineral content changes, surface and subsurface microhardness and ultrastructure were evaluated by Raman intensity mapping, Knoop microhardness and scanning electron microscopy, respectively. Data were statistically analysed using one-way ANOVA with Tukey's test (p < 0.05 is considered as significant). Despite the heterogeneously formed pellicle layer, all groups showed an increase in surface mineral content after pH-cycling. Chitosan pre-treatment enhanced the subsurface remineralisation of WSLs using bioglass as both pre-treated groups showed greater surface and subsurface microhardness compared to NC. CS-BG exhibited denser subsurface structure than BG, while in CS-BG + PAA the crystals were bigger in size but resemble more enamel-like compared to BG + PAA as shown in SEM observations. Remineralisation of RS was limited to the surface as no significant subsurface changes of mechanical properties and structure were found. Chitosan pre-treatment can enhance WSL remineralisation with bioglass biomaterials when a short-term salivary pellicle is present. A further investigation using a long-term pH-cycling model with mature pellicle is suggested with regards to clinical application. Chitosan pre-treatment has the potential in clinical application to remineralise subsurface lesions to achieve lesion consolidation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.

Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site`s microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog {reg_sign} evaluation of enzyme activity in collected water samples.more » Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog{reg_sign} activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.« less

Basement structure based on gravity anomaly in the northern Noto peninsula, Central Japan

NASA Astrophysics Data System (ADS)

Mizubayashi, T.; Sawada, A.; Hamada, M.; Hiramatsu, Y.; Honda, R.

2012-12-01

Upper crustal block structures are usually defined by using surface information, such as geological and morphological data. The northern Noto Peninsula, central Japan, is divided into four geological block structures from tectonic geomorphologic perspectives (Ota and Hirakawa, 1979). This division is based on the surface crustal movement. To image the geological blocks three-dimensionally, it is necessary to construct a subsurface structure model. Gravity survey can clarify the detailed subsurface structure with dense gravity measurement. From the detailed Bouguer anomalies in the northwestern Noto Peninsula, Honda et al. (2008) suggested that the rupture size of the 2007 Noto Hanto earthquake was constrained by the geological block structures. Hiramatsu et al. (2008) also suggested the active faults on the seafloor, such as the source fault of the 2007 Noto Hanto earthquake plays a major role for the formation of the geological block structures. In this study, we analyze subsurface density structure based on the Bouguer anomaly and estimate the distribution of basement depth in the northern Noto Peninsula. We focus the relationship among the basement depth, the block structures and the active faults on the seafloor and discuss the block movement in the northern Noto Peninsula. We compiled the data measured and published previously (Gravity Database of Southwest Japan, 2001; Geological survey of Japan, 2004; Geographical survey institute of Japan, 2006; The Gravity Research Group in Southwest Japan, 2001; Komazawa and Okuma, 2010; Hokuriku electric power Co. Ltd., undisclosed) and calculated Bouguer anomaly in the northern Noto Peninsula. Based on this Bouguer anomaly, we analyzed subsurface density structures along 13 northeastern-southwestern profiles and 35 northwestern-southeastern profiles with the interval of 2 km using the two dimensional Talwani's method (Talwani et al., 1959). In the analysis, we assumed a density structure with four layers: basement (density is 2670kg/m3), Neocene volcanic rock (density is 2400kg/m3, or 2550kg/m3), Neocene sedimentary rock (density is 2200kg/m3), and Quaternary sedimentary rock (density is 1800kg/m3, or 1500kg/m3) (Honda et al., 2008). To compare our basement model to the geological block structures, we focus on a transition zone of the basement depth. We recognize that two of three geological block boundaries correspond to the transition zones. These boundaries also correspond to the boundary of active fault segments on the seafloor. Therefore, based on the relationship between the source fault of the 2007 Noto Hanto earthquake and the geological block, we suggest that the movement of those geological blocks is possibly controlled by the corresponding active fault segments. However, we find that the other block boundary doesn't correspond to the transition zone.

An Examination of Issues Related to a Europa Subsurface Component for the JIMO Mission

NASA Technical Reports Server (NTRS)

Carsey, F. D.; Hecht, M. H.; Wilcox, B. H.; Behar, A. E.; Holland, P. M.

2003-01-01

The Galileo Europa data set served to revolutionize our view of Europa. In particular the strong evidence of a large, cold, salty Ocean beneath 5-30 km of ice has profoundly altered the significance of Europa in our thinking, especially of context of habitability in the solar system. While much remains to be learned from spacecraft observations of several sorts, there are significant questions answerable only by in-situ techniques; these relate to the formation of Europa, the nature of its ocean, and the prospects for life in its ocean, sediments, and ice. We feel that wide-ranging discussion of an in-situ subsurface mission to Europa, as part of JIMO, should proceed. The science objective of the mission is to characterize the icy shell of Europa to resolve its provenance, estimate the composition of brine of the Europa ocean, and search for evidence of Earth-like life. Probably anyone would agree that an in-situ mission to Europa would be of great value, but he or she would also immediately take the position that such a mission is utterly impractical. We take the position here of defining the least complex mission that can nonetheless justify its cost and to argue that such a mission is realistic enough that it should be seriously considered. Our mission thinking has been: 1) Soft landing. A soft lander is required on a site sufficiently flat to offer a stable platform; no further site selectivity is required. 2) Subsurface exploration. The Europa subsurface must be examined. Surficial processes on Europa arguably have exposed the upper 200 m of shell to chemical effects from the Jovian radiation belts as well as cometary infall, etc; to examine native ice we must descend below that point to, for discussion, 300 m. At that depth we argue that the ice is characteristic of ice at depth and possibly is effectively sea ice. 3) Science data. A few simple measurements at various depths and at 300 m constitute a scientifically successful mission. Measurements would include analysis of meltwater for a few inorganic ions and amino acids and an optical examination of the borehole wall. 4) Communication. Transmission of data to an orbiter is essential, but we will constrain the landed mission to a daily communication over a few days. 5) Subsurface access. Drilling to 300 m is a significant challenge; it can be addressed by several means: Thermal Probe (Cryobot) which permits water to refreeze above the vehicle. This is our tentative choice with plutonium as the fuel to generate thermal energy for drilling and electrical power for operations. Open Hole Drill, a thermal system in which the meltwater is removed for greater thermal efficiency. Meltwater removal on Europa is both a complexity and a risk, but analysis is improved. Mechanical Drilling in which cutting or grinding generates ice chips which are removed. This is too complex at Europa temperatures. The measurement objectives for the mission will be: Obj. 1: Determine the concentration of simple inorganic salts in the Europa Ice Shell and, by extrapolation, of the ocean. These data will also validate spaceborne sensors. Obj. 2: Determine the nature and abundance of amino acids in the ice such that cometary infall material in the upper ice can be compared to material at depth. Obj. 3: Optically examine the ice to resolve inclusion structure, particulate content, and stratification. Access to 300 m depth is a significant if not audacious plan; we are aware that this has not been done on any planetary body. Our approach is the use of a plutonium heat source; to overcome Europa's surface temperature and to melt ice a significant amount of plutonium is needed, and significant shielding and other protective steps will be required. The quantity of plutonium is a key concern. The mission will require subsurface collection and processing of samples for in situ analysis, calling for a miniature, high pressure micro-sampling system designed to meet needs of instruments that require low presses for operation. The inlet system itself collects a micro-sample in the external high pressure environment, then transfers it into a protected low pressure environment for analysis.

A Laboratory Approach Relating Complex Resistivity Observations to Flow and Transport in Saturated and Unsaturated Hydrologic Regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martins, S A; Daily, W D; Ramirez, A L

2002-01-31

Subsurface imaging technology, such as electric resistance tomography (ERT), is rapidly improving as a means for characterizing some soil properties of the near-surface hydrologic regime. While this information can be potentially useful in developing hydrologic models of the subsurface that are required for contaminant transport investigations, an image alone of the subsurface soil regime gives little or no information about how the site will respond to groundwater flow or contaminant transport. In fact, there is some question that tomographic imaging of soils alone can even provide meaningful values of hydraulic properties, such as the permeability structure, which is critical tomore » estimates of contaminant transport at a site. The main objective of this feasibility study was to initiate research on electrical imaging not just as a way to characterize the soil structure by mapping different soil types at a site but as a means of obtaining quantitative information about how a site will respond hydrologically to an infiltration event. To this end, a scaled system of electrode arrays was constructed that simulates the subsurface electrode distribution used at the LLNL Vadose Zone Observatory (VZO) where subsurface imaging of infiltration events has been investigated for several years. The electrode system was immersed in a 10,000-gallon tank to evaluate the fundamental relationship between ERT images and targets of a given volume that approximate infiltration-induced conductivity anomalies. With LDRD funds we have explored what can be initially learned about porous flow and transport using two important electrical imaging methods--electric resistance tomography (ERT) and electric impedance tomography (EIT). These tomographic methods involve passing currents (DC or AC) between two electrodes within or between electrode arrays while measuring the electric potential at the remaining electrodes. With the aid of a computer-based numerical inversion scheme, the potentials are used to solve for the electrical conductivity distribution in the region bounded by the electrode arrays. Groundwater movement resulting from a leak or surface spill will produce measurable conductivity changes that have been imaged using ERT or EIT. The kind of laboratory scale experiments supported by this work will help us to better understand the connection between imaged conductivity anomalies and the groundwater or contaminant flow that causes them. This work will also help to demonstrate the feasibility or value of doing lab experiments in imaging that can be applied to interpreting field-scale experiments. A secondary objective of this study was to initiate a collaboration with researchers at the Rensselaer Polytechnic Institute (RPI; Troyl NY) who are also participants in the newly created NSF Center for Subsurface Imaging and Sensing Systems (CenSSIS) which is managed in part by RPI. During the course of this study C.R. Carrigan and W. Daily visited the electromagnetic imaging lab at RPI to initiate discussions on subsurface imaging technology with Professors David Isaacson, Jon Newell, Gary Salunier and their research graduate students. A major goal of CenSSIS is to promote collaborations among researchers with imaging backgrounds in different disciplines (geosciences, biomedical, civil engineering and biomedical) that will lead to new solutions of common subsurface imaging problems. The geophysical test section constructed for this study included electrode arrays that resemble biomedical array distributions. Comparing images of the same target produced with the 4-array geophysical approach and with the biomedical imaging approach will help us to better understand differences and advantages that are characteristic of the two imaging methods. Our initial interactions with the researchers at RPI concluded that this was a viable problem to consider. The support for this subsequent research will come from a 3-year Office of Basic Energy Sciences (BES) proposal that has just received funding. This feasibility study contributed positively to the successful review and ultimately to the award of this BES funding. A letter (Appendix) from Professor Michael Silevitch, Director of CenSSIS, to Dr. Rokaya Al-Ayat, Director of the LLNL Science & Technology Office, acknowledges the contribution of this LDRD study to obtaining the Basic Energy Science grant that will fund further work in this area.« less

A size selective porous silicon grating-coupled Bloch surface and sub-surface wave biosensor.

PubMed

Rodriguez, Gilberto A; Ryckman, Judson D; Jiao, Yang; Weiss, Sharon M

2014-03-15

A porous silicon (PSi) grating-coupled Bloch surface and sub-surface wave (BSW/BSSW) biosensor is demonstrated to size selectively detect the presence of both large and small molecules. The BSW is used to sense large immobilized analytes at the surface of the structure while the BSSW that is confined inside but near the top of the structure is used to sensitively detect small molecules. Functionality of the BSW and BSSW modes is theoretically described by dispersion relations, field confinements, and simulated refractive index shifts within the structure. The theoretical results are experimentally verified by detecting two different small chemical molecules and one large 40 base DNA oligonucleotide. The PSi-BSW/BSSW structure is benchmarked against current porous silicon technology and is shown to have a 6-fold higher sensitivity in detecting large molecules and a 33% improvement in detecting small molecules. This is the first report of a grating-coupled BSW biosensor and the first report of a BSSW propagating mode. © 2013 Published by Elsevier B.V.

Biofilm Effect on Flow Structure over a Permeable Bed

NASA Astrophysics Data System (ADS)

Kazemifar, F.; Blois, G.; Aybar, M.; Perez-Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

2017-12-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Parametrization study of the land multiparameter VTI elastic waveform inversion

NASA Astrophysics Data System (ADS)

He, W.; Plessix, R.-É.; Singh, S.

2018-06-01

Multiparameter inversion of seismic data remains challenging due to the trade-off between the different elastic parameters and the non-uniqueness of the solution. The sensitivity of the seismic data to a given subsurface elastic parameter depends on the source and receiver ray/wave path orientations at the subsurface point. In a high-frequency approximation, this is commonly analysed through the study of the radiation patterns that indicate the sensitivity of each parameter versus the incoming (from the source) and outgoing (to the receiver) angles. In practice, this means that the inversion result becomes sensitive to the choice of parametrization, notably because the null-space of the inversion depends on this choice. We can use a least-overlapping parametrization that minimizes the overlaps between the radiation patterns, in this case each parameter is only sensitive in a restricted angle domain, or an overlapping parametrization that contains a parameter sensitive to all angles, in this case overlaps between the radiation parameters occur. Considering a multiparameter inversion in an elastic vertically transverse isotropic medium and a complex land geological setting, we show that the inversion with the least-overlapping parametrization gives less satisfactory results than with the overlapping parametrization. The difficulties come from the complex wave paths that make difficult to predict the areas of sensitivity of each parameter. This shows that the parametrization choice should not only be based on the radiation pattern analysis but also on the angular coverage at each subsurface point that depends on geology and the acquisition layout.

Detection of Silver Nanoparticles in Vadose Zone Environments using Complex ConductivityMeasurements

EPA Science Inventory

The emergence of engineered nano-materials (ENMs) in the global marketplace and their accidental introduction into the subsurface pose a potential risk to the environment and public health. There is a need for the development of techniques to detect their presence and transport i...

Quasi 3D modeling of water flow in vadose zone and groundwater

USDA-ARS?s Scientific Manuscript database

The complexity of subsurface flow systems calls for a variety of concepts leading to the multiplicity of simplified flow models. One habitual simplification is based on the assumption that lateral flow and transport in unsaturated zone are not significant unless the capillary fringe is involved. In ...

THE INTERPLAY BETWEEN GEOCHEMICAL REACTIONS AND ADVECTION-DISPERSION IN CONTAMINANT TRANSPORT AT A URANIUM MILL TAILINGS SITE

EPA Science Inventory

It is well known that the fate and transport of contaminants in the subsurface are controlled by complex processes including advection, dispersion-diffusion, and chemical reactions. However, the interplay between the physical transport processes and chemical reactions, and their...

GROUNDWATER RECHARGE AND CHEMICAL CONTAMINANTS: CHALLENGES IN COMMUNICATING THE CONNECTIONS AND COLLISIONS OF TWO DISPARATE WORLDS

EPA Science Inventory

The existing knowledge base regarding the presence and significance of chemicals foreign to the subsurface environment is large and growing -the papers in this volume serving as recent testament. But complex questions with few answers surround the unknowns regarding the potenti...

Time-Lapse 3D Inversion of Complex Conductivity Data Using an Active Time Constrained (ATC) Approach

EPA Science Inventory

Induced polarization (more precisely the magnitude and the phase of the impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and ...

STRUCTURE AND FUNCTION OF SUBSURFACE MICROBIAL COMMUNITIES AFFECTING RADIONUCLIDE TRANSPORT AND BIOIMMOBILIZATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joel E. Kostka; Lee Kerkhof; Kuk-Jeong Chin

2011-06-15

The objectives of this project were to: (1) isolate and characterize novel anaerobic prokaryotes from subsurface environments exposed to high levels of mixed contaminants (U(VI), nitrate, sulfate), (2) elucidate the diversity and distribution of metabolically active metal- and nitrate-reducing prokaryotes in subsurface sediments, and (3) determine the biotic and abiotic mechanisms linking electron transport processes (nitrate, Fe(III), and sulfate reduction) to radionuclide reduction and immobilization. Mechanisms of electron transport and U(VI) transformation were examined under near in situ conditions in sediment microcosms and in field investigations at the Oak Ridge Field Research Center (ORFRC), in Oak Ridge, Tennessee, where themore » subsurface is exposed to mixed contamination predominated by uranium and nitrate. A total of 20 publications (16 published or 'in press' and 4 in review), 10 invited talks, and 43 contributed seminars/ meeting presentations were completed during the past four years of the project. PI Kostka served on one proposal review panel each year for the U.S. DOE Office of Science during the four year project period. The PI leveraged funds from the state of Florida to purchase new instrumentation that aided the project. Support was also leveraged by the PI from the Joint Genome Institute in the form of two successful proposals for genome sequencing. Draft genomes are now available for two novel species isolated during our studies and 5 more genomes are in the pipeline. We effectively addressed each of the three project objectives and research highlights are provided. Task I - Isolation and characterization of novel anaerobes: (1) A wide range of pure cultures of metal-reducing bacteria, sulfate-reducing bacteria, and denitrifying bacteria (32 strains) were isolated from subsurface sediments of the Oak Ridge Field Research Center (ORFRC), where the subsurface is exposed to mixed contamination of uranium and nitrate. These isolates which are new to science all show high sequence identity to sequences retrieved from ORFRC subsurface. (2) Based on physiological and phylogenetic characterization, two new species of subsurface bacteria were described: the metal-reducer Geobacter daltonii, and the denitrifier Rhodanobacter denitrificans. (3) Strains isolated from the ORFRC show that Rhodanobacter species are well adapted to the contaminated subsurface. Strains 2APBS1 and 116-2 grow at high salt (3% NaCl), low pH (3.5) and tolerate high concentrations of nitrate (400mM) and nitrite (100mM). Strain 2APBS1 was demonstrated to grow at in situ acidic pHs down to 2.5. (4) R. denitrificans strain 2APBS1 is the first described Rhodanobacter species shown to denitrify. Nitrate is almost entirely converted to N2O, which may account for the large accumulation of N2O in the ORFRC subsurface. (5) G. daltonii, isolated from uranium- and hydrocarbon-contaminated subsurface sediments of the ORFRC, is the first organism from the subsurface clade of the genus Geobacter that is capable of growth on aromatic hydrocarbons. (6) High quality draft genome sequences and a complete eco-physiological description are completed for R. denitrificans strain 2APBS1 and G. daltonii strain FRC-32. (7) Given their demonstrated relevance to DOE remediation efforts and the availability of detailed genotypic/phenotypic characterization, Rhodanobacter denitrificans strain 2APBS1 and Geobacter daltonii strain FRC-32 represent ideal model organisms to provide a predictive understanding of subsurface microbial activity through metabolic modeling. Tasks II and III-Diversity and distribution of active anaerobes and Mechanisms linking electron transport and the fate of radionuclides: (1) Our study showed that members of genus Rhodanobacter and Geobacter are abundant and active in the uranium and nitrate contaminated subsurface. In the contaminant source zone of the Oak Ridge site, Rhodanobacter spp. are the predominant, active organisms detected (comprising 50% to 100% of rRNA detected). (2) We demonstrated for the first time that the function of microbial communities can be quantified in subsurface sediments using messenger RNA assays (molecular proxies) under in situ conditions. (3) Active Geobacteraceae were identified and phylogenetically characterized from the cDNA of messenger RNA extracted from ORFRC subsurface sediment cores. Multiple clone sequences were retrieved from G. uraniireducens, G. daltonii, and G. metallireducens. (4) Results show that Geobacter strain FRC-32 is capable of growth on benzoate, toluene and benzene as the electron donor, thereby providing evidence that this strain is physiologically distinct from other described members of the subsurface Geobacter clade. (5) Fe(III)-reducing bacteria transform structural Fe in clay minerals from their layer edges rather than from their basal surfaces.« less

Proterozoic structure, cambrian rifting, and younger faulting as revealed by a regional seismic reflection network in the Southern Illinois Basin

USGS Publications Warehouse

Potter, C.J.; Drahovzal, James A.; Sargent, M.L.; McBride, J.H.

1997-01-01

Four high-quality seismic reflection profiles through the southern Illinois Basin, totaling 245 km in length, provide an excellent regional subsurface stratigraphic and structural framework for evaluation of seismic risk, hydrocarbon occurrence, and other regional geologic studies. These data provide extensive subsurface information on the geometry of the intersection of the Cambrian Reelfoot and Rough Creek rifts, on extensive Proterozoic reflection sequences, and on structures (including the Fluorspar Area Fault Complex and Hicks Dome) that underlie a transitional area between the well-defined New Madrid seismic zone (to the southwest) and a more diffuse area of seismicity in the southern Illinois Basin. Our principal interpretations from these data are listed here in order of geologic age, from oldest to youngest: 1. Prominent Proterozoic layering, possibly equivalent to Proterozoic (???1 Ga) Middle Run Formation clastic strata and underlying (1.3-1.5 Ga) volcanic rocks of the East Continent rift basin, has been strongly deformed, probably as part of the Grenville foreland fold and thrust belt. 2. A well-defined angular unconformity is seen in many places between Proterozoic and Cambrian strata; a post-Grenville Proterozoic sequence is also apparent locally, directly beneath the base of the Cambrian. 3. We infer a major reversal in Cambrian rift polarity (accommodation zone) in the Rough Creek Graben in western Kentucky. 4. Seismic facies analysis suggests the presence of basin-floor fan complexes at and near the base of the Cambrian interval and within parts of a Proterozoic post-Grenville sequence in several parts of the Rough Creek Graben. 5. There is an abrupt pinchout of the Mount Simon Sandstone against crystalline basement beneath the Dale Dome (near the Texaco no. 1 Cuppy well, Hamilton County) in southeastern Illinois, and a more gradual Mount Simon pinchout to the southeast. 6. Where crossed by the seismic reflection line in southeast Illinois, some faults in the Wabash Valley Fault System produce discrete offset in Ordovician and younger strata only; one of the Wabash Valley faults cuts the top of the Precambrian on this seismic profile. 7. The data show clear evidence of late Paleozoic reverse faulting along both boundaries of the Rough Creek Graben in western Kentucky, although significant unreactivated Cambrian rift-bounding faults are also preserved. 8. Chaotic reflection patterns in the lower and middle Paleozoic strata near Hicks Dome, southern Illinois, are related to a combination of intrusive brecciation, intense faulting, and alteration of carbonate strata by acidic mineralizing fluids, all of which occurred in the Permian. 9. Late Paleozoic(?) reverse faulting is interpreted on one flank of the Rock Creek Graben, southern Illinois. 10. Permian and Mesozoic(?) extensional faulting is clearly imaged in the Fluorspar Area Fault Complex; neotectonic studies suggest that these structures were reactivated in the Quaternary.

A Subsurface Soil Composition and Physical Properties Experiment to Address Mars Regolith Stratigraphy

NASA Technical Reports Server (NTRS)

Richter, L.; Sims, M.; Economou, T.; Stoker, C.; Wright, I.; Tokano, T.

2004-01-01

Previous in-situ measurements of soil-like materials on the surface of Mars, in particular during the on-going Mars Exploration Rover missions, have shown complex relationships between composition, exposure to the surface environment, texture, and local rocks. In particular, a diversity in both compositional and physical properties could be established that is interpreted to be diagnostic of the complex geologic history of the martian surface layer. Physical and chemical properties vary laterally and vertically, providing insight into the composition of rocks from which soils derive, and environmental conditions that led to soil formation. They are central to understanding whether habitable environments existed on Mars in the distant past. An instrument the Mole for Soil Compositional Studies and Sampling (MOCSS) - is proposed to allow repeated access to subsurface regolith on Mars to depths of up to 1.5 meters for in-situ measurements of elemental composition and of physical and thermophysical properties, as well as for subsurface sample acquisition. MOCSS is based on the compact PLUTO (PLanetary Underground TOol) Mole system developed for the Beagle 2 lander and incorporates a small X-ray fluorescence spectrometer within the Mole which is a new development. Overall MOCSS mass is approximately 1.4 kilograms. Taken together, the MOCSS science data support to decipher the geologic history at the landing site as compositional and textural stratigraphy if they exist - can be detected at a number of places if the MOCSS were accommodated on a rover such as MSL. Based on uncovered stratigraphy, the regional sequence of depositional and erosional styles can be constrained which has an impact on understanding the ancient history of the Martian near-surface layer, considering estimates of Mars soil production rates of 0.5... 1.0 meters per billion years on the one hand and Mole subsurface access capability of approximately 1.5 meters. An overview of the MOCSS, XRS instrument accomodation and the impact that these instruments have on Mars science is discussed.

Correlating High Resolution Radar Reflectors with Visible Layering of the Polar Layered Deposits, Mars

NASA Astrophysics Data System (ADS)

Christian, S.; Holt, J. W.; Choudhary, P.; Fishbaugh, K. E.; Plaut, J. J.

2010-12-01

The Shallow Radar (SHARAD) onboard NASA’s Mars Reconnaissance Orbiter (MRO) has successfully detected many subsurface reflectors in the North Polar Layered Deposits (NPLD) of Mars. Confirming that these reflectors are caused by varying fractions of dust within the ice will be of primary importance in any attempt to model the composition of the NPLD, particularly if such a study incorporates optical data based on the assumption of a shared mechanism between layering and radar reflectance. As a first step towards examining this assumption, we have quantitatively studied the relationship between radar reflectors and adjacent visible layers exposed in an NPLD outcrop using statistical analyses and geometric comparisons. A clustering analysis of vertical separation distances between radar reflectors returned strong values at 11.8, 15.8, 20.3, 27.9, and 35.3 m, which strongly agree with published visible layer clusters [Fishbaugh et al., LPSC, 2009] and known frequency analysis results [Milkovich and Head, JGR, 2005]. Furthermore, in order to understand subsurface structures and reflector geometry we have gridded reflector surfaces in three dimensions, taking into account the influence of surface slopes to obtain accurate subsurface geometries. These geometries reveal average reflector dips of 0.4°, which are consistent with optical layer slopes on the order of 1.0°. Unexpected long wavelength topography resulting from subsurface structures visible to SHARAD complicated the attempt to compare radar reflector geometries with layer boundary elevation profiles obtained from the stratigraphic column produced using a digital elevation model (DEM) of High Resolution Imaging Science Experiment (HiRISE) stereo imagery [Fishbaugh et al., GRL, 2010]. The limitation imposed by the small extent of the DEM was resolved by increasing exposure coverage through the incorporation of images from Context Camera (CTX), also on MRO. In doing so, we were able to resolve the disparity between geometries and have now determined visible layers demonstrate similar subsurface topographic features as those revealed by SHARAD. Direct elevation comparisons between individual reflectors and discrete optical layers, while considered necessary for a correlation, are complicated by variations in subsurface structure that exist between the outcrop and the SHARAD tracks, as inferred from our mapping. While a direct correlation has not yet been accomplished, we have confirmed a genetic link between radar reflectors and visible layers; furthermore, we have generalized and improved the techniques for conducting such correlations so this can be undertaken at additional locations.

The Ultramafic Complex of Reinfjord: from the Magnetic Petrology to the Interpretation of the Magnetic Anomalies

NASA Astrophysics Data System (ADS)

Pastore, Zeudia; McEnroe, Suzanne; Church, Nathan; Fichler, Christine; ter Maat, Geertje W.; Fumagalli, Patrizia; Oda, Hirokuni; Larsen, Rune B.

2017-04-01

A 3D model of the geometry of the Reinfjord complex integrating geological and petrophysical data with high resolution aeromagnetic, ground magnetic and gravity data is developed. The Reinfjord ultramafic complex in northern Norway is one of the major ultramafic complexes of the Neoproterozoic Seiland Igneous Province (SIP). This province, now embedded in the Caledonian orogen, was emplaced deep in the crust (30 km of depth) and is believed to represent a section of the deep plumbing system of a large igneous province. The Reinfjord complex consists of three magmatic series formed during multiple recharging events resulting in the formation of a cylindrically zoned complex with a slightly younger dunite core surrounded by wehrlite and lherzolite units. Gabbros and gneiss form the host rock. The ultramafic complex has several distinct magnetic anomalies which do not match the mapped lithological boundaries, but are correlated with changes in magnetic susceptibilities. In particular, the deviating densities and magnetic susceptibilities at the northern side of the complex are interpreted to be due to serpentinization. Detailed studies of magnetic anomalies and magnetic properties of samples can provide a powerful tool for mapping petrological changes. Samples can have wide range of magnetic properties depending on composition, amount of ferromagnetic minerals, grain sizes and microstructures. Later geological processes such as serpentinization can alter this signal. Therefore a micro-scale study of magnetic anomalies at the thin section scale was carried out to understand better the link between the magnetic petrology and the magnetic anomalies. Serpentinization can significantly enhance the magnetic properties and therefore change the nature of the magnetic anomaly. The detailed gravity and magnetic model here presented shows the subsurface structure of the ultramafic complex refining the geological interpretation of the magnetic sources within it, and the local effects of serpentinization.

Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

PubMed

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.

High Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ki Ha; Becker, Alex; Framgos, William

1999-06-01

Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data can bemore » mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately imaging the electrical conductivity and dielectric permittivity of the shallow subsurface using the plane wave impedance approach. Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques.« less

High-Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ki Ha; Becker, Alex; Tseng, Hung-Wen

2002-11-20

Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic (EM) measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data canmore » be mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using the EM impedance approach (Frangos, 2001; Lee and Becker, 2001; Song et al., 2002). Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques.« less

High-Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring, and Verification Efforts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ki Ha; Becker, Alex

2000-06-01

Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data can bemore » mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately imaging the electrical conductivity and dielectric permittivity of the shallow subsurface using the plane wave impedance approach (Song et al., 1997). Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques.« less

High-Frequency Electromagnetic Impedance Measurements for Characterization, Monitoring and Verification Efforts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ki Ha; Becker, Alex; Tseng, Hung-Wen

2001-06-10

Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic (EM) measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high-resolution imaging, accurate measurements are necessary so the field data canmore » be mapped into the space of the subsurface parameters. We are developing a non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using the EM impedance approach (Frangos, 2001; Lee and Becker, 2001). Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques.« less

The feeding system of the Lusi eruption revealed by ambient noise tomography

NASA Astrophysics Data System (ADS)

Javad Fallahi, Mohammad; Obermann, Anne; Lupi, Matteo; Mazzini, Adriano

2017-04-01

Lusi is a clastic dominated geysering system located in the northeastern Java backarc basin in Indonesia. Based on fluid geochemistry it has been described as a newborn sedimentary-hosted hydrothermal system. The present study provides a 3D model of shear wave velocity anomaly beneath Lusi and the neighboring Arjuno-Welirang volcanic complex and aims to better understand the subsurface structures as well as the Lusi plumbing system. To date, our data represent the first image of a hydrothermal plume in the upper crust seen with geophysical methods. We use 10 months of ambient noise data recorded by 31 temporary seismic stations and use ambient noise tomography methods to obtain the shear wave velocity model. The obtained tomographic images reveal the presence of a low velocity zone that connects the Arjuno-Welirang volcanic complex at about 5 km depth and ultimately emerging at the Lusi eruption site. Magmatic reservoirs beneath volcanic systems are also identified. Low shear wave anomalies representing magmatic reservoirs are less pronounced for the Arjuno-Welirang volcanic complex (the oldest system investigated in this study), intermediate beneath the Penanggungan volcano and result much more pronounced beneath the newborn Lusi. The results obtained in this study are consistent with a scenario envisaging a magmatic intrusion at depth and/or hydrothermal fluids migrating from the volcanic complex and extending towards the sedimentary basin.

3D Seismic Imaging using Marchenko Methods

NASA Astrophysics Data System (ADS)

Lomas, A.; Curtis, A.

2017-12-01

Marchenko methods are novel, data driven techniques that allow seismic wavefields from sources and receivers on the Earth's surface to be redatumed to construct wavefields with sources in the subsurface - including complex multiply-reflected waves, and without the need for a complex reference model. In turn, this allows subsurface images to be constructed at any such subsurface redatuming points (image or virtual receiver points). Such images are then free of artefacts from multiply-scattered waves that usually contaminate migrated seismic images. Marchenko algorithms require as input the same information as standard migration methods: the full reflection response from sources and receivers at the Earth's surface, and an estimate of the first arriving wave between the chosen image point and the surface. The latter can be calculated using a smooth velocity model estimated using standard methods. The algorithm iteratively calculates a signal that focuses at the image point to create a virtual source at that point, and this can be used to retrieve the signal between the virtual source and the surface. A feature of these methods is that the retrieved signals are naturally decomposed into up- and down-going components. That is, we obtain both the signal that initially propagated upwards from the virtual source and arrived at the surface, separated from the signal that initially propagated downwards. Figure (a) shows a 3D subsurface model with a variable density but a constant velocity (3000m/s). Along the surface of this model (z=0) in both the x and y directions are co-located sources and receivers at 20-meter intervals. The redatumed signal in figure (b) has been calculated using Marchenko methods from a virtual source (1200m, 500m and 400m) to the surface. For comparison the true solution is given in figure (c), and shows a good match when compared to figure (b). While these 2D redatuming and imaging methods are still in their infancy having first been developed in 2012, we have extended them to 3D media and wavefields. We show that while the wavefield effects may be more complex in 3D, Marchenko methods are still valid, and 3D images that are free of multiple-related artefacts, are a realistic possibility.

3D elastic full waveform inversion: case study from a land seismic survey

NASA Astrophysics Data System (ADS)

Kormann, Jean; Marti, David; Rodriguez, Juan-Esteban; Marzan, Ignacio; Ferrer, Miguel; Gutierrez, Natalia; Farres, Albert; Hanzich, Mauricio; de la Puente, Josep; Carbonell, Ramon

2016-04-01

Full Waveform Inversion (FWI) is one of the most advanced processing methods that is recently reaching a mature state after years of solving theoretical and technical issues such as the non-uniqueness of the solution and harnessing the huge computational power required by realistic scenarios. BSIT (Barcelona Subsurface Imaging Tools, www.bsc.es/bsit) includes a FWI algorithm that can tackle with very complex problems involving large datasets. We present here the application of this system to a 3D dataset acquired to constrain the shallow subsurface. This is where the wavefield is the most complicated, because most of the wavefield conversions takes place in the shallow region and also because the media is much more laterally heterogeneous. With this in mind, at least isotropic elastic approximation would be suitable as kernel engine for FWI. The current study explores the possibilities to apply elastic isotropic FWI using only the vertical component of the recorded seismograms. The survey covers an area of 500×500 m2, and consists in a receivers grid of 10 m×20 m combined with a 250 kg accelerated weight-drop as source on a displaced grid of 20 m×20 m. One of the main challenges in this case study is the costly 3D modeling that includes topography and substantial free surface effects. FWI is applied to a data subset (shooting lines 4 to 12), and is performed for 3 frequencies ranging from 15 to 25 Hz. The starting models are obtained from travel-time tomography and the all computation is run on 75 nodes of Mare Nostrum supercomputer during 3 days. The resulting models provide a higher resolution of the subsurface structures, and show a good correlation with the available borehole measurements. FWI allows to extend in a reliable way this 1D knowledge (borehole) to 3D.

Prestack reverse time migration for tilted transversely isotropic media

NASA Astrophysics Data System (ADS)

Jang, Seonghyung; Hien, Doan Huy

2013-04-01

According to having interest in unconventional resource plays, anisotropy problem is naturally considered as an important step for improving the seismic image quality. Although it is well known prestack depth migration for the seismic reflection data is currently one of the powerful tools for imaging complex geological structures, it may lead to migration error without considering anisotropy. Asymptotic analysis of wave propagation in transversely isotropic (TI) media yields a dispersion relation of couple P- and SV wave modes that can be converted to a fourth order scalar partial differential equation (PDE). By setting the shear wave velocity equal zero, the fourth order PDE, called an acoustic wave equation for TI media, can be reduced to couple of second order PDE systems and we try to solve the second order PDE by the finite difference method (FDM). The result of this P wavefield simulation is kinematically similar to elastic and anisotropic wavefield simulation. We develop prestack depth migration algorithm for tilted transversely isotropic media using reverse time migration method (RTM). RTM is a method for imaging the subsurface using inner product of source wavefield extrapolation in forward and receiver wavefield extrapolation in backward. We show the subsurface image in TTI media using the inner product of partial derivative wavefield with respect to physical parameters and observation data. Since the partial derivative wavefields with respect to the physical parameters require extremely huge computing time, so we implemented the imaging condition by zero lag crosscorrelation of virtual source and back propagating wavefield instead of partial derivative wavefields. The virtual source is calculated directly by solving anisotropic acoustic wave equation, the back propagating wavefield on the other hand is calculated by the shot gather used as the source function in the anisotropic acoustic wave equation. According to the numerical model test for a simple geological model including syncline and anticline, the prestack depth migration using TTI-RTM in weak anisotropic media shows the subsurface image is similar to the true geological model used to generate the shot gathers.

Effects of leaf area index on the coupling between water table, land surface energy fluxes, and planetary boundary layer at the regional scale

NASA Astrophysics Data System (ADS)

Lu, Y.; Rihani, J.; Langensiepen, M.; Simmer, C.

2013-12-01

Vegetation plays an important role in the exchange of moisture and energy at the land surface. Previous studies indicate that vegetation increases the complexity of the feedbacks between the atmosphere and subsurface through processes such as interception, root water uptake, leaf surface evaporation, and transpiration. Vegetation cover can affect not only the interaction between water table depth and energy fluxes, but also the development of the planetary boundary layer. Leaf Area Index (LAI) is shown to be a major factor influencing these interactions. In this work, we investigate the sensitivity of water table, surface energy fluxes, and atmospheric boundary layer interactions to LAI as a model input. We particularly focus on the role LAI plays on the location and extent of transition zones of strongest coupling and how this role changes over seasonal timescales for a real catchment. The Terrestrial System Modelling Platform (TerrSysMP), developed within the Transregional Collaborative Research Centre 32 (TR32), is used in this study. TerrSysMP consists of the variably saturated groundwater model ParFlow, the land surface model Community Land Model (CLM), and the regional climate and weather forecast model COSMO (COnsortium for Small-scale Modeling). The sensitivity analysis is performed over a range of LAI values for different vegetation types as extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) dataset for the Rur catchment in Germany. In the first part of this work, effects of vegetation structure on land surface energy fluxes and their connection to water table dynamics are studied using the stand-alone CLM and the coupled subsurface-surface components of TerrSysMP (ParFlow-CLM), respectively. The interconnection between LAI and transition zones of strongest coupling are investigated and analyzed through a subsequent set of subsurface-surface-atmosphere coupled simulations implementing the full TerrSysMP model system.

Electrical resistance tomography during in-situ trichloroethylene remediation at the Savannah River Site

NASA Astrophysics Data System (ADS)

Daily, W.; Ramirez, A.

1995-04-01

Electrical resistance tomography was used to monitor in-situ remediation processes for removal of volatile organic compounds from subsurface water and soil at the Savannah River Site near Aiken, South Carolina. This work was designed to test the feasibility of injecting a weak mixture of methane in air as a metabolic carbon source for natural microbial populations which are capable of trichloroethylene degradation. Electrical resistance tomograms were constructed of the subsurface during the test to provide detailed images of the process. These images were made using an iterative reconstruction algorithm based on a finite element forward model and Newton-type least-squares minimization. Changes in the subsurface resistivity distribution were imaged by a pixel-by-pixel subtraction of images taken before and during the process. This differential tomography removed all static features of formation resistivity but clearly delineated dynamic features induced by remediation processes. The air-methane mixture was injected into the saturated zone and the intrained air migration paths were tomographically imaged by the increased resistivity of the path as air displaced formation water. We found the flow paths to be confined to a complex three-dimensional network of channels, some of which extended as far as 30 m from the injection well. These channels were not entirely stable over a period of months since new channels appeared to form with time. Also, the resistivity of the air injection paths increased with time. In another series of tests, resistivity images of water infiltration from the surface support similar conclusions about the preferential permeability paths in the vadose zone. In this case, the water infiltration front is confined to narrow channels which have a three-dimensional structure. Here, similar to air injection in the saturated zone, the water flow is controlled by local variations in formation permeability. However, temporal changes in these channels are minor, indicating that the permeable paths do not seem to be modified by continued infiltration.

Sorption of Pseudomonas putida onto differently structured kaolinite minerals

NASA Astrophysics Data System (ADS)

Vasiliadou, I. A.; Papoulis, D.; Chrysikopoulos, C.; Panagiotaras, D.; Karakosta, E.; Fardis, M.; Papavassiliou, G.

2010-12-01

The presence of bio-colloids (e.g. bacteria and viruses) in the subsurface could be attributed to the release of particles from septic tanks, broken sewer lines or from artificial recharge with treated municipal wastewater. Bio-colloid transport in the subsurface is significantly affected by sorption onto the solid matrix. Bio-colloid attachment onto mobile or suspended in the aqueous phase soil particles (e.g. clay or other minerals) also may influence their fate and transport in the subsurface. The present study focuses on the investigation of Pseudomonas (Ps.) putida sorption onto well (KGa-1) and poorly (KGa-2) crystallized kaolinite minerals. Batch experiments were carried out to determine the sorption isotherms of Ps. putida onto both types of kaolinite particles. The sorption process of Ps. putida onto KGa-1 and KGa-2 is adequately described by a Langmuir isotherm. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy as well as Nuclear Magnetic Resonance were employed to study the sorption mechanisms of Ps. putida. Experimental results indicated that KGa-2 presented higher affinity and sorption capacity than KGa-1. It was shown that electrostatic interactions and structural disorders can influence the sorption capacity of clay particles.

New views of the Gulf Stream

NASA Astrophysics Data System (ADS)

Todd, R. E.

2016-02-01

The Gulf Stream plays a major role in the climate system and is a significant forcing agent for the coastal circulation along the US East Coast, yet routine subsurface measurements of Gulf Stream structure are only collected in the Florida Straits and between New Jersey and Bermuda. A recent pilot program demonstrated the feasibility of using underwater gliders to repeatedly survey across the Gulf Stream and to provide subsurface Gulf Stream observations to the community in realtime. Spray gliders were deployed on three-month missions from Miami, Florida to the New England shelf south of Cape Cod, during which they zigzagged back and forth across the Gulf Stream. Three such deployments have been completed so far with a total of more than 20 cross-Gulf Stream transects occupied. These new observations detail the subsurface structure and variability of the Gulf Stream upstream and downstream of its separation from the continental margin, reveal large-amplitude internal waves within the boundary current, and capture numerous eddies along the flanks of the Gulf Stream. Future routine glider deployments in the Gulf Stream promise to provide critical observations for examining inherent Gulf Stream variability, investigating western boundary current influences on coastal circulation, and constraining numerical simulations.

Exploring the hydraulic fracturing parameter space: a novel high-pressure, high-throughput reactor system for investigating subsurface chemical transformations.

PubMed

Sumner, Andrew J; Plata, Desiree L

2018-02-21

Hydraulic fracturing coupled with horizontal drilling (HDHF) involves the deep-well injection of a fracturing fluid composed of diverse and numerous chemical additives designed to facilitate the release and collection of natural gas from shale plays. Analyses of flowback wastewaters have revealed organic contamination from both geogenic and anthropogenic sources. The additional detections of undisclosed halogenated chemicals suggest unintended in situ transformation of reactive additives, but the formation pathways for these are unclear in subsurface brines. To develop an efficient experimental framework for investigating the complex shale-well parameter space, we have reviewed and synthesized geospatial well data detailing temperature, pressure, pH, and halide ion values as well as industrial chemical disclosure and concentration data. Our findings showed subsurface conditions can reach pressures up to 4500 psi (310 bars) and temperatures up to 95 °C, while at least 588 unique chemicals have been disclosed by industry, including reactive oxidants and acids. Given the extreme conditions necessary to simulate the subsurface, we briefly highlighted existing geochemical reactor systems rated to the necessary pressures and temperatures, identifying throughput as a key limitation. In response, we designed and developed a custom reactor system capable of achieving 5000 psi (345 bars) and 90 °C at low cost with 15 individual reactors that are readily turned over. To demonstrate the system's throughput, we simultaneously tested 12 disclosed HDHF chemicals against a radical initiator compound in simulated subsurface conditions, ruling out a dozen potential transformation pathways in a single experiment. This review outlines the dynamic and diverse parameter range experienced by HDHF chemical additives and provides an optimized framework and novel reactor system for the methodical study of subsurface transformation pathways. Ultimately, enabling such studies will provide urgently needed clarity for water treatment downstream or releases to the environment.

Integrated surface and groundwater modelling in the Thames Basin, UK using the Open Modelling Interface

NASA Astrophysics Data System (ADS)

Mackay, Jonathan; Abesser, Corinna; Hughes, Andrew; Jackson, Chris; Kingdon, Andrew; Mansour, Majdi; Pachocka, Magdalena; Wang, Lei; Williams, Ann

2013-04-01

The River Thames catchment is situated in the south-east of England. It covers approximately 16,000 km2 and is the most heavily populated river basin in the UK. It is also one of the driest and has experienced severe drought events in the recent past. With the onset of climate change and human exploitation of our environment, there are now serious concerns over the sustainability of water resources in this basin with 6 million m3 consumed every day for public water supply alone. Groundwater in the Thames basin is extremely important, providing 40% of water for public supply. The principal aquifer is the Chalk, a dual permeability limestone, which has been extensively studied to understand its hydraulic properties. The fractured Jurassic limestone in the upper catchment also forms an important aquifer, supporting baseflow downstream during periods of drought. These aquifers are unconnected other than through the River Thames and its tributaries, which provide two-thirds of London's drinking water. Therefore, to manage these water resources sustainably and to make robust projections into the future, surface and groundwater processes must be considered in combination. This necessitates the simulation of the feedbacks and complex interactions between different parts of the water cycle, and the development of integrated environmental models. The Open Modelling Interface (OpenMI) standard provides a method through which environmental models of varying complexity and structure can be linked, allowing them to run simultaneously and exchange data at each timestep. This architecture has allowed us to represent the surface and subsurface flow processes within the Thames basin at an appropriate level of complexity based on our understanding of particular hydrological processes and features. We have developed a hydrological model in OpenMI which integrates a process-driven, gridded finite difference groundwater model of the Chalk with a more simplistic, semi-distributed conceptual model of the Jurassic limestone. A distributed river routing model of the Thames has also been integrated to connect the surface and subsurface hydrological processes. This application demonstrates the potential benefits and issues associated with implementing this approach.

The design of long wavelength planetary SAR sensor and its applications for monitoring shallow sub-surface of Moon and planets.

NASA Astrophysics Data System (ADS)

Kim, K.

2015-12-01

SAR observations over planetary surface have been conducted mainly in two ways. The first is the subsurface sounding, for example Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) and Shallow Surface Radar (SHARAD), using ground penetration capability of long wavelength electromagnetic waves. On the other hand, imaging SAR sensors using burst mode design have been employed to acquire surface observations in the presence of opaque atmospheres such as in the case of Venus and Titan. We propose a lightweight SAR imaging system with P/L band wavelength to cover the vertical observation gap of these planetary radar observation schemes. The sensor is for investigating prominent surface and near-subsurface geological structures and physical characteristics. Such measurements will support landers and rover missions as well as future manned missions. We evaluate required power consumption, and estimate mass and horizontal resolution, which can be as good as 3-7 meters. Initial specifications for P/L dual band SARs for the lunar case at 130 km orbital altitude were designed already based on a assumptions that sufficient size antenna (>3m width diameter or width about 3m and >10kg weight) can be equipped. Useful science measurements to be obtained include: (1) derivation of subsurface regolith depth; 2) Surface and shallow subsurface radar imaging, together with radar ranging techniques such as radargrammetry and inteferometry. The concepts in this study can be used as an important technical basis for the future solid plant/satellite missions and already proposed for the 2018 Korean Lunar mission.

Trans-dimensional Bayesian inversion of airborne electromagnetic data for 2D conductivity profiles

NASA Astrophysics Data System (ADS)

Hawkins, Rhys; Brodie, Ross C.; Sambridge, Malcolm

2018-02-01

This paper presents the application of a novel trans-dimensional sampling approach to a time domain airborne electromagnetic (AEM) inverse problem to solve for plausible conductivities of the subsurface. Geophysical inverse field problems, such as time domain AEM, are well known to have a large degree of non-uniqueness. Common least-squares optimisation approaches fail to take this into account and provide a single solution with linearised estimates of uncertainty that can result in overly optimistic appraisal of the conductivity of the subsurface. In this new non-linear approach, the spatial complexity of a 2D profile is controlled directly by the data. By examining an ensemble of proposed conductivity profiles it accommodates non-uniqueness and provides more robust estimates of uncertainties.

Glass sample preparation and performance investigations. [solar x-ray imager

NASA Technical Reports Server (NTRS)

Johnson, R. Barry

1992-01-01

This final report details the work performed under this delivery order from April 1991 through April 1992. The currently available capabilities for integrated optical performance modeling at MSFC for large and complex systems such as AXAF were investigated. The Integrated Structural Modeling (ISM) program developed by Boeing for the U.S. Air Force was obtained and installed on two DECstations 5000 at MSFC. The structural, thermal and optical analysis programs available in ISM were evaluated. As part of the optomechanical engineering activities, technical support was provided in the design of support structure, mirror assembly, filter wheel assembly and material selection for the Solar X-ray Imager (SXI) program. As part of the fabrication activities, a large number of zerodur glass samples were prepared in different sizes and shapes for acid etching, coating and polishing experiments to characterize the subsurface damage and stresses produced by the grinding and polishing operations. Various optical components for AXAF video microscope and the x-ray test facility were also fabricated. A number of glass fabrication and test instruments such as a scatter plate interferometer, a gravity feed saw and some phenolic cutting blades were fabricated, integrated and tested.

Diversity of basaltic lunar volcanism associated with buried impact structures: Implications for intrusive and extrusive events

NASA Astrophysics Data System (ADS)

Zhang, F.; Zhu, M.-H.; Bugiolacchi, R.; Huang, Q.; Osinski, G. R.; Xiao, L.; Zou, Y. L.

2018-06-01

Relatively denser basalt infilling and the upward displacement of the crust-mantle interface are thought to be contributing factors for the quasi-circular mass anomalies for buried impact craters in the lunar maria. Imagery and gravity observations from the Lunar Reconnaissance Orbiter (LRO) and dual Gravity Recovery and Interior Laboratory (GRAIL) missions have identified 10 partially or fully buried impact structures where diversity of observable basaltic mare volcanism exists. With a detailed investigation of the characteristics of associated volcanic landforms, we describe their spatial distribution relationship with respect to the subsurface tectonic structure of complex impact craters and propose possible models for the igneous processes which may take advantage of crater-related zones of weakness and enable magmas to reach the surface. We conclude that the lunar crust, having been fractured and reworked extensively by cratering, facilitates substance and energy exchange between different lunar systems, an effect modulated by tectonic activities both at global and regional scales. In addition, we propose that the intrusion-caused contribution to gravity anomalies should be considered in future studies, although this is commonly obscured by other physical factors such as mantle uplift and basalt load.