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Sample records for airborne geophysical methods

  1. Geophysical methods

    SciTech Connect

    Robert, E.S.

    1989-01-01

    Geophysical measurements involve no magic or mystery but straightforward applications of physical principles. This book is both a geophysical survey and a reference guide. It explains the physical principles involved in geophysical methods. Over one-third of the text is devoted to seismic methods. Comprehensive topics in the volume include: the measurement of different physical properties and their geological significance; how different kinds of measurements are combined to draw geological conclusions; surface, borehole, airborne, and satellite measurements; computer processing and interactive methods; geodetic, gravity, magnetic, radioactive, heat flow, and electrical methods; interpretation of natural processes such as earthquakes and heat flow; and a summation of present knowledge of the earth.

  2. International Symposium on Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  3. A general framework of TOPSIS method for integration of airborne geophysics, satellite imagery, geochemical and geological data

    NASA Astrophysics Data System (ADS)

    Abedi, Maysam; Norouzi, Gholam-Hossain

    2016-04-01

    This work presents the promising application of three variants of TOPSIS method (namely the conventional, adjusted and modified versions) as a straightforward knowledge-driven technique in multi criteria decision making processes for data fusion of a broad exploratory geo-dataset in mineral potential/prospectivity mapping. The method is implemented to airborne geophysical data (e.g. potassium radiometry, aeromagnetic and frequency domain electromagnetic data), surface geological layers (fault and host rock zones), extracted alteration layers from remote sensing satellite imagery data, and five evidential attributes from stream sediment geochemical data. The central Iranian volcanic-sedimentary belt in Kerman province at the SE of Iran that is embedded in the Urumieh-Dokhtar Magmatic Assemblage arc (UDMA) is chosen to integrate broad evidential layers in the region of prospect. The studied area has high potential of ore mineral occurrences especially porphyry copper/molybdenum and the generated mineral potential maps aim to outline new prospect zones for further investigation in future. Two evidential layers of the downward continued aeromagnetic data and its analytic signal filter are prepared to be incorporated in fusion process as geophysical plausible footprints of the porphyry type mineralization. The low values of the apparent resistivity layer calculated from the airborne frequency domain electromagnetic data are also used as an electrical criterion in this investigation. Four remote sensing evidential layers of argillic, phyllic, propylitic and hydroxyl alterations were extracted from ASTER images in order to map the altered areas associated with porphyry type deposits, whilst the ETM+ satellite imagery data were used as well to map iron oxide layer. Since potassium alteration is generally the mainstay of porphyry ore mineralization, the airborne potassium radiometry data was used. The geochemical layers of Cu/B/Pb/Zn elements and the first component of PCA

  4. The use of airborne geophysics for levee classification and assessment

    NASA Astrophysics Data System (ADS)

    Dunbar, Joseph B.

    2011-12-01

    This research is the first known application into using airborne geophysical methods to evaluate and classify levees. This research is an important step toward developing new technologies and methods to rapidly screen and evaluate earthen flood control levees for safety against flooding. An investigation of airborne geophysical methods was conducted on levees in the lower Rio Grande Valley and involved electromagnetic induction, magnetometer, and LiDAR surveys of the levee system. Airborne EM signatures were analyzed by geologic mapping of floodplain depositional environments, examination of published soils data, and drilling of borings. A geographic information system was developed to manage the various data sets and evaluate historic land use changes and development of the flood control systems to better understand the signatures using airborne methods. This research presents information about the historic basis for evaluating and classifying levees, which is based primarily on the federal perspective and flood control experiences in the lower Mississippi River Valley, where national floodplain engineering methods and standards were developed. This research examines the evolution of today's flood control policy, and the development of engineering assessment procedures, and the application of geophysical methods to provide critical information about levee failure mechanisms and assessment of flood control systems. This research demonstrates that topographic base maps and Sengpiel sections showing the results of electrical conductivity or resistivity surveys at different frequencies along the levee corridor provide accurate and valuable information to determine the composition of floodplain soils and the foundation stratigraphy to assess modes of levee failure, to aid in the placement of borings to obtain material properties of the levee and foundation, and to determine the extent of levee reaches with similar properties for the engineering analysis. The main

  5. Airborne Geophysical Surveys Applied to Hydrocarbon Resource Development Environmental Studies

    NASA Astrophysics Data System (ADS)

    Smith, B. D.; Ball, L. B.; Finn, C.; Kass, A.; Thamke, J.

    2014-12-01

    Application of airborne geophysical surveys ranges in scale from detailed site scale such as locating abandoned well casing and saline water plumes to landscape scale for mapping hydrogeologic frameworks pertinent to ground water and tectonic settings relevant to studies of induced seismicity. These topics are important in understanding possible effects of hydrocarbon development on the environment. In addition airborne geophysical surveys can be used in establishing baseline "snapshots", to provide information in beneficial uses of produced waters, and in mapping ground water resources for use in well development. The U.S. Geological Survey (USGS) has conducted airborne geophysical surveys over more than 20 years for applications in energy resource environmental studies. A majority of these surveys are airborne electromagnetic (AEM) surveys to map subsurface electrical conductivity related to plumes of saline waters and more recently to map hydrogeologic frameworks for ground water and plume migration. AEM surveys have been used in the Powder River Basin of Wyoming to characterize the near surface geologic framework for siting produced water disposal ponds and for beneficial utilization in subsurface drip irrigation. A recent AEM survey at the Fort Peck Reservation, Montana, was used to map both shallow plumes from brine pits and surface infrastructure sources and a deeper concealed saline water plume from a failed injection well. Other reported applications have been to map areas geologically favorable for shallow gas that could influence drilling location and design. Airborne magnetic methods have been used to image the location of undocumented abandoned well casings which can serve as conduits to the near surface for coproduced waters. They have also been used in conjunction with geologic framework studies to understand the possible relationships between tectonic features and induced earthquakes in the Raton Basin. Airborne gravity as well as developing deeper

  6. Alternative analysis of airborne laser data collected within conventional multi-parameter airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Ahl, Andreas; Supper, R.; Motschka, K.; Schattauer, I.

    2010-05-01

    . These results encouraged us to apply these methods to airborne geophysical data sets from the United Mexican States. One survey was targeted to provide additional data for advanced groundwater modeling in remote areas of the karstic plateau of Yucatan. Within the other project a sustainable source of water supply for a small settlement on the isolated island of Socorro, 700 km off the Mexican main coast had to be detected. At both survey areas no accurate elevation models or area-wide information about vegetation heights where available before the airborne geophysical survey. The results of these investigations will be presented. From an evaluation of the results it can be concluded that the use of laser altimetry not only provides essential information about the ground clearance of the geophysical instruments but also increases the benefit of the airborne survey for the client by delivering additional information about the survey area. It is clear that the accuracy of the resulting data cannot compete with a high resolution laser scanning survey. However in areas where such information is not available an obvious additional benefit can be achieved without the need to spend money for additional survey campaigns. Currently further studies are launched to investigate the possibility to increase the accuracy of the altitude data by determining roll and pitch of the helicopter by the use of differentially corrected multiple L1/L2 band GPS receiver mounted at fixed positions on the helicopter platform. The above study was partly financed by the Austrian Science Fund, Xplore (L524-N10) project.

  7. Airborne geophysical surveys over the eastern Adirondacks, New York State

    USGS Publications Warehouse

    Shah, Anjana K.

    2016-01-01

    Airborne geophysical surveys were conducted in the eastern Adirondacks from Dec. 7, 2015 - Dec. 21, 2015, by Goldak Airborne Surveys. The area was flown along a draped surface with a nominal survey height above ground of 200 meters. The flight line spacing was 250 meters for traverse lines and 2500 meters for control lines. Here we present downloadable magnetic and radiometric (gamma spectrometry) data from those surveys as image (Geotiff) and flight line data (csv format).BackgroundThe Eastern Adirondacks region was known for iron mining in the 1800's and 1900's but it also contains deposits of rare earth minerals. Rare earth minerals are used in advanced technology such as in cell phones, rechargeable batteries and super-magnets. In many areas rare earth minerals appear to be associated with iron ore.The surveys were flown in order to map geologic variations in three dimensions. Magnetic surveys measure subtle changes in Earth's magnetic field that reflect different types of buried rock, such as iron-rich ore bodies. Radiometric methods detect naturally occurring gamma particles. The energy spectra of these particles can be used to estimate relative amounts of potassium, uranium and thorium (also referred to as gamma ray spectrometry), which are sometimes associated with rare earth elements. Together, these data provide insights into the regional tectonic and magmatic history as well as mineral resources in the area.

  8. The State of the Industry and Research in Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Hodges, G.

    2007-12-01

    Development of airborne geophysical methods has tended to proceed in rushes of energy, when many new systems are developed for the same application simultaneously along many pathways. The tremendous growth of airborne EM through the '50s to '70s was followed by natural selection in the '80s and '90s down to two styles: fixed-wing aircraft with high-powered time domain systems (FTEM) offering depth of exploration but poor spatial resolution, and helicopter-borne frequency-domain systems (HFEM) offering the best resolution but poor depth of exploration. At the end of the '90s there was an incredible spurt of energy toward helicopter time domain development, spurred technological advances in electronics and materials. By 2007 there were 8 systems operational. Perhaps the most daring current research is toward airborne EM systems utilizing ambient EM fields as sources. Magnetic sensors are almost universally cesium-vapor total field sensors (0.01nT sampled at 0.1s). Because the limitation on target detection is ambient, in-band noise, there is little to gain from producing higher-sensitivity meters. Data quality improvements are being sought by measuring horizontal and vertical gradients more accurately. The new wave of research for magnetic surveys is the measurement of vector or tensor magnetic data with directional sensors, generally either fluxgates or SQUIDS. Magnetometers on autonomous aircraft are newly available. Gamma Ray Spectrometry surveys with sodium-iodide crystal detectors give good performance, and the low cost allows for large volumes to make up for the relatively low sensitivity. The last few years have seen development of new systems in which each crystal in the detector array is monitored, calibrated and stabilized individually using natural radiation. Airborne gravity systems available use the LaCoste zero-length pendulum, or orthogonal accelerometers. Separation of gravity from acceleration is generally done with platforms stabilized for both

  9. THE GERMAN NORTH SEA COAST IN FOCUS OF AIRBORNE GEOPHYSICAL INVESTIGATIONS

    NASA Astrophysics Data System (ADS)

    Steuer, A.; Siemon, B.; Schaumann, G.; Wiederhold, H.; Meyer, U.; Binot, F.; Kühne, K.

    2009-12-01

    In recent years airborne geophysical methods have turned out to have great potential in delineating subsurface information down to some hundred meters depth. This information is essential for planning purposes for manifold geoscientific, economic or environmental questions, like, e.g., utilization and protection of freshwater resources, land utilization or industrial planning. These data integrated into a three-dimensional geographical information system provide a perfect tool for spatial planning. Beside the geologic or geophysical basic information also changes of surface and subsurface data in time and space may be documented by repeated surveys. Especially electromagnetic induction is the most versatile of the airborne geophysical methods and widely applied in hydrogeological investigations because the measurements respond to both lithologic and water-chemistry variations. The applications include geologic mapping and aquifer structure, delineation of soil and groundwater salinization, salt-water intrusion into coastal aquifers etc. Building on previous results and knowledge a general airborne survey of the German North Sea coastal area started in 2008. Emphasis is placed on the mapping of fresh-/saltwater interfaces (e.g., North Sea island Borkum), saltwater intrusions and the evaluation of the coastal aquifers (e.g., Elbe estuary) as well as on the mapping of submarine freshwater occurrence (e.g., Langeoog, Wadden Sea). With the mapping a basis for monitoring should be set up.

  10. Clean enough for industry? An airborne geophysical case study

    SciTech Connect

    Nyquist, J.E.; Beard, L.P.

    1996-11-01

    Data from two airborne geophysical surveys of the Department of Energy`s Oak Ridge Reservation (ORR) were extremely valuable in deciding whether a 1000-acre (400 hectare) parcel of the ORR should be leased to the City of Oak Ridge for industrial development. Our findings, based on electromagnetic and magnetic data, were incorporated in the federally mandated Environmental Assessment Statement (EAS), and in general supported claims that this land was never used as a hazardous waste disposal site. We estimated the amount of iron required to produce each anomaly using a simple dipole model. All anomalies with equivalent sources greater than approximately 1000 kg of iron were checked in the field, and the source of all but one identified as either a bridge, reinforced concrete debris, or a similarly benign object. Additionally, some smaller anomalies (equivalent sources of roughly 500 kg) have been checked; thus far, these also have innocuous sources. Airborne video proved invaluable in identifying logging equipment as the source of some of these anomalies. Geologic noise may account for some of the remaining anomalies. Naturally occurring accumulations of magnetic minerals in the soil on the ORR have been shown to produce anomalies which, at a sensor height of 30 in, are comparable to the anomaly produced by about 500 kg of iron. By comparison, the electronic noise of the magnetic gradiometer, 0.01- 0.02 nT/m, is equivalent to only about 50-100 kg of iron at a 30 m sensor height. The electromagnetic data, combined with field mapping of karst structures, provided evidence of a northeast-southwest striking conduit spanning the parcel. The possible existence of a karst conduit led the EAS authors to conclude that this is a {open_quotes}sensitive hydrologic setting.{close_quotes} We conclude that aerial geophysics is an extremely cost-effective, and efficient technique for screening large tracts of land for environmental characterization.

  11. Clean enough for industry? An airborne geophysical case study

    SciTech Connect

    Nyquist, J.E.; Beard, L.P.

    1996-02-01

    Data from two airborne geophysical surveys of the Department of Energy`s Oak Ridge Reservation (ORR) were extremely valuable in deciding whether a 1000-acre (400 hectare) parcel of the ORR should be released to the City of Oak Ridge for industrial development. Our findings, based on electromagnetic and magnetic data, were incorporated in the federally mandated Environmental Assessment Statement (EAS), and in general supported claims that this land was never used as a hazardous waste disposal site. We estimated the amount of iron required to produce each anomaly using a simple dipole model. All anomalies with equivalent sources greater than approximately 1000 kg of iron were checked in the field, and the source of all but one identified as either a bridge, reinforced concrete debris, or a similarly benign object. Additionally, some smaller anomalies (equivalent sources of roughly 500 kg) have been checked; thus far, these also have innocuous sources. Airborne video proved invaluable in identifying logging equipment as the source of some of these anomalies. Geologic noise may account for some of the remaining anomalies. Naturally occurring accumulations of magnetic minerals in the soil on the ORR have been shown to produce anomalies which, at a sensor height of 30 m, are comparable to the anomaly produced by about 500 kg of iron. By comparison, the electronic noise of the magnetic gradiometer, 0.01--0.02 nT/m, is equivalent to only about 50--100 kg of iron at a 30 m sensor height. The electromagnetic data, combined with field mapping of karst structures, provided evidence of a northeast-southwest striking conduit spanning the parcel. The possible existence of a karst conduit led the EAS authors to conclude that this is a ``sensitive hydrologic setting.`` We conclude that aerial geophysics is an extremely cost-effective, and efficient technique for screening large tracts of land for environmental characterization.

  12. Airborne wireless communication systems, airborne communication methods, and communication methods

    DOEpatents

    Deaton, Juan D [Menan, ID; Schmitt, Michael J [Idaho Falls, ID; Jones, Warren F [Idaho Falls, ID

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  13. Applications of geophysical methods to volcano monitoring

    USGS Publications Warehouse

    Wynn, Jeff; Dzurisin, Daniel; Finn, Carol A.; Kauahikaua, James P.; Lahusen, Richard G.

    2006-01-01

    The array of geophysical technologies used in volcano hazards studies - some developed originally only for volcano monitoring - ranges from satellite remote sensing including InSAR to leveling and EDM surveys, campaign and telemetered GPS networks, electronic tiltmeters and strainmeters, airborne magnetic and electromagnetic surveys, short-period and broadband seismic monitoring, even microphones tuned for infrasound. They include virtually every method used in resource exploration except large-scale seismic reflection. By “geophysical ” we include both active and passive methods as well as geodetic technologies. Volcano monitoring incorporates telemetry to handle high-bandwith cameras and broadband seismometers. Critical geophysical targets include the flux of magma in shallow reservoir and lava-tube systems, changes in active hydrothermal systems, volcanic edifice stability, and lahars. Since the eruption of Mount St. Helens in Washington State in 1980, and the eruption at Pu’u O’o in Hawai’i beginning in 1983 and still continuing, dramatic advances have occurred in monitoring technology such as “crisis GIS” and lahar modeling, InSAR interferograms, as well as gas emission geochemistry sampling, and hazards mapping and eruption predictions. The on-going eruption of Mount St. Helens has led to new monitoring technologies, including advances in broadband Wi-Fi and satellite telemetry as well as new instrumentation. Assessment of the gap between adequate monitoring and threat at the 169 potentially dangerous Holocene volcanoes shows where populations are dangerously exposed to volcanic catastrophes in the United States and its territories . This paper focuses primarily on Hawai’ian volcanoes and the northern Pacific and Cascades volcanoes. The US Geological Survey, the US National Park System, and the University of Utah cooperate in a program to monitor the huge Yellowstone volcanic system, and a separate observatory monitors the restive Long Valley

  14. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    SciTech Connect

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT E) project by EG G Energy Measurement's (EG G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory's unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  15. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    SciTech Connect

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT&E) project by EG&G Energy Measurement`s (EG&G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory`s unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG&G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  16. Airborne and spaceborne lasers for terrestrial geophysical sensing; Proceedings of the Meeting, Los Angeles, CA, Jan. 14, 15, 1988

    NASA Technical Reports Server (NTRS)

    Allario, Frank (Editor)

    1988-01-01

    The present conference on airborne and spaceborne remote sensing laser applications discusses topics in atmospheric and geophysical sciences-related sensors, lidar and DIAL component and subsystem technologies, and coherent laser experiments and semiconductor laser technologies. Attention is given to airborne lidar measurement of aerosols, a ground-based injection-locked pulsed TEA laser for wind measurements, chemical/biological agent standoff detection methods, lidars for wind shear erosion, laser tuning to selected gas absorption lines in the atmosphere, the NASA lidar-in-space technology experiment, and the Laser Atmospheric Wind Sounder.

  17. Investigation of coastal areas in Northern Germany using airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Miensopust, Marion; Siemon, Bernhard; Wiederhold, Helga; Steuer, Annika; Ibs-von Seht, Malte; Voß, Wolfgang; Meyer, Uwe

    2014-05-01

    Since 2000, the German Federal Institute for Geosciences and Natural Resources (BGR) carried out several airborne geophysical surveys in Northern Germany to investigate the coastal areas of the North Sea and some of the North and East Frisian Islands. Several of those surveys were conducted in cooperation with the Leibniz Institute for Applied Geophysics (LIAG). Two helicopter-borne geophysical systems were used, namely the BGR system, which collects simultaneously frequency-domain electromagnetic, magnetic and radiometric data, and the SkyTEM system, a time-domain electromagnetic system developed by the University of Aarhus. Airborne geophysical surveys enable to investigate huge areas almost completely with high lateral resolution in a relatively short time at economic cost. In general, the results can support geological and hydrogeological mapping. Of particular importance are the airborne electromagnetic results, as the surveyed parameter - the electrical conductivity - depends on both lithology and groundwater status. Therefore, they can reveal buried valleys and the distribution of sandy and clayey sediments as well as salinization zones and fresh-water occurrences. The often simultaneously recorded magnetic and radiometric data support the electromagnetic results. Lateral changes of Quaternary and Tertiary sediments (shallow source - several tens of metres) as well as evidences of the North German Basin (deep source - several kilometres) are revealed by the magnetic results. The radiometric data indicate the various mineral compositions of the soil sediments. This BGR/LIAG project aims to build up a geophysics data base (http://geophysics-database.de/) which contains all airborne geophysical data sets. However, the more significant effort is to create a reference data set as basis for monitoring climate or man-made induced changes of the salt-water/fresh-water interface at the German North Sea coast. The significance of problems for groundwater extraction

  18. Geophysical methods for locating abandoned wells

    USGS Publications Warehouse

    Frischknecht, Frank C.; Muth, L.; Grette, R.; Buckley, T.; Kornegay, B.

    1983-01-01

    A preliminary study of the feasibility of using geophysical exploration methods to locate abandoned wells containing steel casing indicated that magnetic methods promise to be effective and that some electrical techniques might be useful as auxiliary methods. Ground magnetic measurements made in the vicinity of several known cased wells yielded total field anomalies with peak values ranging from about 1,500 to 6,000 gammas. The anomalies measured on the ground are very narrow and, considering noise due to other cultural and geologic sources, a line spacing on the order of 50 feet (15.2 m) would be necessary to locate all casings in the test area. The mathematical model used to represent a casing was a set of magnetic pole pairs. By use of a non-linear least squares curve fitting (inversion) program, model parameters which characterize each test casing were determined. The position and strength of the uppermost pole was usually well resolved. The parameters of lower poles were not as well resolved but it appears that the results are adequate for predicting the anomalies which would be observed at aircraft altitudes. Modeling based on the parameters determined from the ground data indicates that all of the test casings could be detected by airborne measurements made at heights of 150 to 200 feet (45.7-61.0 m) above the ground, provided lines spaced as closely as 330 feet (100 m) were used and provided noise due to other cultural and geologic sources is not very large. Given the noise levels of currently available equipment and assuming very low magnetic gradients due to geologic sources, the detection range for total field measurements is greater than that for measurements of the horizontal or vertical gradient of the total intensity. Electrical self-potential anomalies were found to be associated with most of the casings where measurements were made. However, the anomalies tend to be very narrow and, in several cases, they are comparable in magnitude to other small

  19. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  20. Airborne geophysical surveys conducted in western Nebraska, 2010: contractor reports and data

    USGS Publications Warehouse

    ,

    2014-01-01

    This report contains three contractor reports and data files for an airborne electromagnetic survey flown from June 28 to July 7, 2010. The first report; “SkyTEM Survey: Nebraska, USA, Data” describes data aquisition and processing from a time-domain electromagnetic and magnetic survey performed by SkyTEM Canada, Inc. (the North American SkyTEM subsidiary), in western Nebraska, USA. Digital data for this report are given in Appendix 1. The airborne geophysical data from the SkyTEM survey subsequently were processed and inverted by Aarhus Geophysics ApS, Aarhus, Denmark, to produce resistivity depth sections along each flight line. The result of that processing is described in two reports presented in Appendix 2, “Processing and inversion of SkyTEM data from USGS Area UTM–13” and “Processing and inversion of SkyTEM data from USGS Area UTM–14.” Funding for these surveys was provided by the North Platte Natural Resources District, the South Platte Natural Resources District, and the Twin Platte Natural Resources District, in Scottsbluff, Sidney, and North Platte, Nebraska, respectively. Any additional information concerning the geophysical data may be obtained from the U.S. Geological Survey Crustal Geophysics and Geochemistry Science Center, Denver Colorado.

  1. A multi-scale permafrost investigation along the Alaska Highway Corridor based on airborne electromagnetic and auxiliary geophysical data

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Kass, M. A.; Bloss, B.; Pastick, N.; Panda, S. K.; Smith, B. D.; Abraham, J. D.; Burns, L. E.

    2012-12-01

    More than 8000 square kilometers of airborne electromagnetic (AEM) data were acquired along the Alaska Highway Corridor in 2005-2006 by the Alaska Department of Natural Resources Division of Geological and Geophysical Surveys. Because this large AEM dataset covers diverse geologic and permafrost settings, it is an excellent testbed for studying the electrical geophysical response from a wide range of subsurface conditions. These data have been used in several recent investigations of geology, permafrost, and infrastructure along the highway corridor. In this study, we build on existing interpretations of permafrost features by re-inverting the AEM data using traditional least squares inversion techniques as well as recently developed stochastic methods aimed at quantifying uncertainty in geophysical data. Ground-based geophysical measurements, including time-domain electromagnetic soundings, surface nuclear magnetic resonance soundings, and shallow frequency-domain electromagnetic profiles, have also been acquired to help validate and extend the AEM interpretations. Here, we focus on the integration of different types of data to yield an improved characterization of permafrost, including: methods to discriminate between geologic and thermal controls on resistivity; identifying relationships between shallow resistivity and active layer thickness by incorporating auxiliary remote sensing data and ground-based measurements; quantifying apparent slope-aspect-resistivity relationships, where south-facing slopes appear less resistive than north-facing slopes within similar geologic settings; and investigating an observed decrease in resistivity beneath several areas associated with recent fires.

  2. Faulting and Groundwater in Arid Environments: Ground and Airborne Geophysics in Support of Framework Hydrology

    NASA Astrophysics Data System (ADS)

    Bedrosian, P. A.; Burgess, M. K.; Bloss, B.; Ball, L. B.; Polster, S.; Densmore, J.; Martin, P.; Langenheim, V. E.; Jachens, R. C.

    2011-12-01

    In the Mojave Desert of the southwestern USA, groundwater is compartmentalized within a series of fault-bounded basins. As part of an effort to understand and manage groundwater resources in arid environments, the USGS is investigating basins within the Fort Irwin National Training Center through a combination of hydrologic, geophysical, and geochemical approaches. Airborne time-domain electromagnetic (TDEM) data were collected within the Leach Basin, a geologically complex, internally-drained basin bisected and flanked by a number of Quaternary faults, including the Garlock fault and the Death Valley fault zone. The airborne TDEM data provide subsurface constraints down to approximately 200 m depth, and show abrupt changes in earth response across faulted boundaries, reflecting the strong lateral resistivity contrast between igneous rocks and basin sediments. Intra-basin faults are additionally identified, and to a lesser extent faults within the igneous basement can be traced. The distribution of faults throughout the basin and within the subsurface can thus be directly obtained from the airborne data. These electrical discontinuities, however, present challenges for the laterally-constrained inversion approach we applied, and we present alternative approaches to inverting these data which honor the complexity of the region. We further outline a multivariate approach to fault identification which combines resistivity models, airborne magnetics, and surface topography. A resistivity stratigraphy has been developed using borehole geophysical logs, ground-based gravity, TDEM soundings, and lab resistivity measurements from nearby basins. The results are applied to the airborne resistivity models and used to trace aquifer hydrostratigraphy throughout the basin. Interpreted parameters include the depth to basement, the base of the primary aquifer, depth to water, and variations in groundwater salinity. Together with hydrologic investigations, these results are being

  3. Satellite imagery and airborne geophysics for geologic mapping of the Edembo area, Eastern Hoggar (Algerian Sahara)

    NASA Astrophysics Data System (ADS)

    Lamri, Takfarinas; Djemaï, Safouane; Hamoudi, Mohamed; Zoheir, Basem; Bendaoud, Abderrahmane; Ouzegane, Khadidja; Amara, Massinissa

    2016-03-01

    Satellite imagery combined with airborne geophysical data and field observations were employed for new geologic mapping of the Edembo area in the Eastern Hoggar (Tuareg Shield, Sahara). Multi-spectral band fusion, filtering, and transformation techniques, i.e., band combination, band-rationing and principal component analysis of ETM+ and ASTER data are used for better spectral discrimination of the different rocks units. A thematic map assessed by field data and available geologic information is compiled by supervised classification of satellite data with high overall accuracy (>90%). The automated extraction technique efficiently aided the detection of the structural lineaments, i.e., faults, shear zones, and joints. Airborne magnetic and Gamma-ray spectrometry data showed the pervasiveness of the large structures beneath the Paleozoic sedimentary cover and aeolian sands. The aeroradiometric K-range is used for discrimination of the high-K granitoids of Djanet from the peralumineous granites of Edembo, and to verify the Silurian sediments with their high K-bearing minerals. The new geological map is considered to be a high resolution improvement on all pre-existing maps of this hardly accessible area in the Tuareg Shield. Integration of the airborne geophysical and space-borne imagery data can hence provide a rapid means of geologically mapping areas hitherto poorly known or difficult to access.

  4. Radon potential determination by a combination of geological mapping, geochemistry, groundwater investigations and airborne geophysics

    NASA Astrophysics Data System (ADS)

    Schubert, G.; Motschka, K.; Ahl, A.; Slapansky, P.; Finger, F.; Alletsgruber, I.; Gasser, V.; Supper, R.; Bieber, G.

    2009-04-01

    During the nineties comprehensive Radon investigations were carried out in Austria to determine the Radon exposure of the population (Ditto et al., 1999, Friedmann et al.,1997 and Friedmann et al., 2007). Friedmann (2007, p 16-17) came to the result that indoor measurements can be better used than geological methods to pinpoint areas with a high Radon hazard. Contrary to this conclusion, in the current presentation we intend to show that geological factors are the most important parameters for Radon potential evaluation and we demonstrate a new mapping method for determining the spatial distribution of the Radon potential by means of geological and airborne geophysical investigations. Within the last years, several test sites in the southern Bohemian Massive were investigated. Based on large scaled geological maps different types of Granites were analysed on Uranium content. Furthermore, in order to obtain the spatial distribution of Uranium, close-meshed airborne radiometric mapping was carried out. Additionally, ground water samples were analysed to derive representative Radon concentrations for the pore volume within the different Granite types. Final results concluded that there is a significant correlation between the Uranium content of the geological subsurface and the Radon concentration in the ground water (SCHUBERT et al., 2003, ALLETSGRUBER, 2007). As a consequence airborne radiometric mapping could be used as an effective tool to derive quick and detailed information on spatial distribution of the Radon potential. Furthermore this methodology could contribute to identify potential Radon hot spot areas as only airborne radiometric mapping could provide countrywide Uranium data coverage in high resolution. I. Alletsgruber(2007): Radongehalte in Grundwässern des Mühlviertels (Oberösterreich). Geologische und hydrogeologische Faktoren. - diploma thesis, Univ. Salzburg. PT M. Ditto, W. Fimml, V. Karg, M. Korner, J. Weisz (1999): Radon-222 im Grundwasser

  5. Geophysical methods for road construction and maintenance

    NASA Astrophysics Data System (ADS)

    Rasul, Hedi; Karlson, Caroline; Jamali, Imran; Earon, Robert; Olofsson, Bo

    2015-04-01

    Infrastructure, such as road transportation, is a vital in civilized societies; which need to be constructed and maintained regularly. A large part of the project cost is attributed to subsurface conditions, where unsatisfactory conditions could increase either the geotechnical stabilization measures needed or the design cost itself. A way to collect information of the subsurface and existing installations which can lead to measures reducing the project cost and damage is to use geophysical methods during planning, construction and maintenance phases. The moisture in road layers is an important factor, which will affect the bearing capacity of the construction as well as the maintenances. Moisture in the road is a key factor for a well-functioning road. On the other hand the excessive moisture is the main reason of road failure and problems. From a hydrological point of view geophysical methods could help road planners identify the water table, geological strata, pollution arising from the road and the movement of the pollution before, during and after construction. Geophysical methods also allow road planners to collect valuable data for a large area without intrusive investigations such as with boreholes, i.e. minimizing the environmental stresses and costs. However, it is important to specify the investigation site and to choose the most appropriate geophysical method based on the site chosen and the objective of the investigation. Currently, numerous construction and rehabilitation projects are taking places around the world. Many of these projects are focused on infrastructural development, comprising both new projects and expansion of the existing infrastructural network. Geophysical methods can benefit these projects greatly during all phases. During the construction phase Ground Penetrating radar (GPR) is very useful in combination with Electrical Resistivity (ER) for detecting soil water content and base course compaction. However, ER and Electromagnetic

  6. Application of geophysical methods for fracture characterization

    SciTech Connect

    Lee, K.H.; Majer, E.L.; McEvilly, T.V. |; Morrison, H.F. |

    1990-01-01

    One of the most crucial needs in the design and implementation of an underground waste isolation facility is a reliable method for the detection and characterization of fractures in zones away from boreholes or subsurface workings. Geophysical methods may represent a solution to this problem. If fractures represent anomalies in the elastic properties or conductive properties of the rocks, then the seismic and electrical techniques may be useful in detecting and characterizing fracture properties. 7 refs., 3 figs.

  7. Geophysical and Geodetic Analysis of Airborne Gravity Data from GRAV-D in Alaska

    NASA Astrophysics Data System (ADS)

    Diehl, T. M.; Preaux, S.; Childers, V. A.

    2009-12-01

    The U.S. National Geodetic Survey’s mission is to define and maintain the spatial reference system of the United States. Official policy, adopted in 2008, calls for the definition a new national vertical datum based on a gravimetric geoid by 2018 and for its maintenance into the future. The project that will accomplish data collection and analysis tasks toward that goal is called GRAV-D (Gravity for the Redefinition of the American Vertical Datum). The project is underway to collect new airborne gravity data across the entire U.S. To date, GRAV-D has collected nearly 1 million sq km of high-altitude airborne gravity data at 12,500 ft to 35,000 ft. Data sets exist in Alaska, Puerto Rico and the Virgin Islands, and the coastal Gulf of Mexico from the Florida panhandle to the Mexican border. In support of the GRAV-D mission, information about the geologic setting of the data sets and geophysical interpretations of the gravity data are necessary. For instance, geodetic concerns about knowledge of an area’s density structure for completing geoid calculations within topography can be addressed with geophysical interpretation techniques. Here we examine GRAV-D data located in a tectonically and topographically complex area of the country near Anchorage, AK and Fairbanks, AK. We assess the contribution of information gained from gravity analysis techniques, combined with information from geologic studies, for geodetic application in the area.

  8. A survey of natural aggregate properties and characteristics important in remote sensing and airborne geophysics

    USGS Publications Warehouse

    Knepper, D.H.; Langer, W.H.; Miller, S.

    1995-01-01

    Natural aggregate is vital to the construction industry. Although natural aggregate is a high volume/low value commodity that is abundant, new sources are becoming increasingly difficult to find and develop because of rigid industry specifications, political considerations, development and transportation costs, and environmental concerns. There are two primary sources of natural aggregate: (1) exposed or near-surface bedrock that can be crushed, and (2) deposits of sand and gravel. Remote sensing and airborne geophysics detect surface and near-surface phenomena, and may be useful for detecting and mapping potential aggregate sources; however, before a methodology for applying these techniques can be developed, it is necessary to understand the type, distribution, physical properties, and characteristics of natural aggregate deposits. The distribution of potential aggregate sources is closely tied to local geologic history. Conventional exploration for natural aggregate deposits has been largely a ground-based operation, although aerial photographs and topographic maps have been extensively used to target possible deposits. Today, the exploration process also considers factors such as the availability of the land, space and water supply for processing, political and environmental factors, and distance from the market; exploration and planning cannot be separated. There are many physical properties and characteristics by which to judge aggregate material for specific applications; most of these properties and characteristics pertain only to individual aggregate particles. The application of remote sensing and airborne geophysical measurements to detecting and mapping potential aggregate sources, however, is based on intrinsic bulk physical properties and extrinsic characteristics of the deposits that can be directly measured, mathematically derived from measurement, or interpreted with remote sensing and geophysical data. ?? 1995 Oxford UniversityPress.

  9. Geophysical methods for monitoring infiltration in soil

    NASA Astrophysics Data System (ADS)

    Coquet, Yves; Pessel, Marc; Saintenoy, Albane

    2015-04-01

    Geophysics provides useful tools for monitoring water infiltration in soil essentially because they are non-invasive and have a good time-resolution. We present some results obtained on different soils using two geophysical techniques: electrical resistivity tomography (ERT) and ground-penetrating radar (GPR). Infiltration in a loamy soil was monitored using a 2D Wenner array set up under a tension disc infiltrometer. A good imaging of the infiltration bulb below the infiltrometer could be achieved provided a sufficient resistivity contrast between the wet and the dry soil zones. ERT data could be used to invert soil hydraulic properties. However, we found that the information provided by the ERT could be of limited importance in regard to the information provided by the infiltration rate dynamics if the ERT spatial resolution is not small enough to capture the details of the infiltration front at the limit between the wet and dry soil zones. GPR was found to be a good tool to monitor the progression of the infiltration front in a sandy soil. By combining a water transport simulation model (HYDRUS-1D), a method for transforming water content into dielectric permittivity values (CRIM), and an electromagnetic wave propagation model (GprMax), the Mualem-van Genuchten hydraulic parameters could be retrieved from radargrams obtained under constant or falling head infiltration experiments. Both ERT and GPR methods have pros and cons. Time and spatial resolutions are of prime importance to achieve a sufficient sensitivity to all soil hydraulic parameters. Two exploration fields are suggested: the combination of different geophysical methods to explore infiltration in heterogeneous soils, and the development of integrated infiltrometers that allow geophysical measurements while monitoring water infiltration rate in soil.

  10. Peat Depth Assessment Using Airborne Geophysical Data for Carbon Stock Modelling

    NASA Astrophysics Data System (ADS)

    Keaney, Antoinette; McKinley, Jennifer; Ruffell, Alastair; Robinson, Martin; Graham, Conor; Hodgson, Jim; Desissa, Mohammednur

    2013-04-01

    The Kyoto Agreement demands that all signatory countries have an inventory of their carbon stock, plus possible future changes to this store. This is particularly important for Ireland, where some 16% of the surface is covered by peat bog. Estimates of soil carbon stores are a key component of the required annual returns made by the Irish and UK governments to the Intergovernmental Panel on Climate Change. Saturated peat attenuates gamma-radiation from underlying rocks. This effect can be used to estimate the thickness of peat, within certain limits. This project examines this relationship between peat depth and gamma-radiation using airborne geophysical data generated by the Tellus Survey and newly acquired data collected as part of the EU-funded Tellus Border project, together encompassing Northern Ireland and the border area of the Republic of Ireland. Selected peat bog sites are used to ground truth and evaluate the use of airborne geophysical (radiometric and electromagnetic) data and validate modelled estimates of soil carbon, peat volume and depth to bedrock. Data from two test line sites are presented: one in Bundoran, County Donegal and a second line in Sliabh Beagh, County Monaghan. The plane flew over these areas at different times of the year and at a series of different elevations allowing the data to be assessed temporally with different soil/peat saturation levels. On the ground these flight test lines cover varying surface land use zones allowing future extrapolation of data from the sites. This research applies spatial statistical techniques, including uncertainty estimation in geostatistical prediction and simulation, to investigate and model the use of airborne geophysical data to examine the relationship between reduced radioactivity and peat depth. Ground truthing at test line locations and selected peat bog sites involves use of ground penetrating radar, terrestrial LiDAR, peat depth probing, magnetometry, resistivity, handheld gamma

  11. Crisp clustering of airborne geophysical data from the Alto Ligonha pegmatite field, northeastern Mozambique, to predict zones of increased rare earth element potential

    NASA Astrophysics Data System (ADS)

    Eberle, Detlef G.; Daudi, Elias X. F.; Muiuane, Elônio A.; Nyabeze, Peter; Pontavida, Alfredo M.

    2012-01-01

    . The highest probability to meet pegmatite bodies is in close vicinity to (magnetic) amphibole schist occurring in areas where depletion of potassium as indication of metasomatic processes is evident from the airborne radiometric data. Clustering has proven to be a fast and effective method to compile value-added maps from multivariate geophysical datasets. Experience made in the Alto Ligonha pegmatite field encourages adopting this new methodology for mapping other parts of the Mozambique Fold Belt.

  12. Review of geophysical characterization methods used at the Hanford Site

    SciTech Connect

    GV Last; DG Horton

    2000-03-23

    This paper presents a review of geophysical methods used at Hanford in two parts: (1) shallow surface-based geophysical methods and (2) borehole geophysical methods. This review was not intended to be ``all encompassing'' but should represent the vast majority (>90% complete) of geophysical work conducted onsite and aimed at hazardous waste investigations in the vadose zone and/or uppermost groundwater aquifers. This review did not cover geophysical methods aimed at large-scale geologic structures or seismicity and, in particular, did not include those efforts conducted in support of the Basalt Waste Isolation Program. This review focused primarily on the more recent efforts.

  13. Integration and analysis of airborne geophysical data of the Darrehzar area, Kerman Province, Iran, using principal component analysis

    NASA Astrophysics Data System (ADS)

    Ranjbar, H.; Hassanzadeh, H.; Torabi, M.; Ilaghi, O.

    2001-08-01

    This paper describes a methodology for the integrated interpretation of airborne magnetic and airborne γ-ray spectrometer data. The Darrehzar porphyry copper deposit is situated in the Urumieh-Dokhtar magmatic assemblage of Central Iran. Phyllic and propylitic alterations are pervasive in the area but potassic and argillic alterations are not readily recognized on the surface. The spatial distributions of geophysical data resemble the lithological and alteration patterns in the area. The Darrehzar porphyry copper deposit is considered as a control site for determination of the degrees that the geophysical data is correlated with the mineralization zone. Airborne magnetic/radiometric, and geochemical/alteration data sets have been integrated and analyzed using principal component analysis. This technique is found to be useful for the delineation of hydrothermally altered areas and data compression.

  14. Measuring Geophysical Parameters of the Greenland Ice Sheet using Airborne Radar Altimetry

    NASA Technical Reports Server (NTRS)

    Ferraro, Ellen J.; Swift. Calvin T.

    1995-01-01

    This paper presents radar-altimeter scattering models for each of the diagenetic zones of the Greenland ice sheet. AAFE radar- altimeter waveforms obtained during the 1991 and 1993 NASA multi-sensor airborne altimetry experiments over Greenland reveal that the Ku-band return pulse changes significantly with the different diagenetic zones. These changes are due to varying amounts of surface and volume scattering in the return waveform. In the ablation and soaked zones, where surface scattering dominates the AAFE return, geophysical parameters such as rms surface height and rms surface slope are obtained by fitting the waveforms to a surface-scattering model. Waveforms from the percolation zone show that the sub-surface ice features have a much more significant effect on the return pulse than the surrounding snowpack. Model percolation waveforms, created using a combined surface- and volume-scattering model and an ice-feature distribution obtained during the 1993 field season, agree well with actual AAFE waveforms taken in the same time period. Using a combined surface- and volume-scattering model for the dry-snow-zone return waveforms, the rms surface height and slope and the attenuation coefficient of the snowpack are obtained. These scattering models not only allow geophysical parameters of the ice sheet to be measured but also help in the understanding of satellite radar-altimeter data.

  15. Three decades of BGR airborne geophysical surveys over the polar regions - a review

    NASA Astrophysics Data System (ADS)

    Damaske, Detlef

    2013-04-01

    The Federal Institute for Geosciences and Natural Resources (BGR) has been conducting geological polar research since 1979. A few years later BGR engaged in airborne geophysical projects. Investigation of the lithosphere of the continent and the continental margins was one of the key issues for BGR. Right from the beginning geophysical research was closely associated with the geological activities. The GANOVEX (German Antarctic North Victoria Land Expedition) program combined geological research with geophysical (mainly airborne) investigations. This proved to be a fruitful approach to many of the open questions regarding the tectonic development of the Ross Sea region. Aeromagnetic surveys evolved into a powerful tool for identifying geological structures and following them underneath the ice covered areas - not accessible to direct geological investigations. To achieve this aim it was essential to lay out these surveys with a relatively closely spaced line separation on the expense of covering large areas at the same time. Nevertheless, over many years of continues research areas of more than a just regional extent could be covered. This was, however, only possible through international collaboration. During the first years, working in the Ross Sea area, the cooperation with the US and Italian programs played a significant role, especially the GITARA (German-Italian Aeromagnetic Research in Antarctica) program has to be mentioned. GEOMAUD (Geoscientific Expedition to Dronning Maud Land) and the German-Australian joint venture PCMEGA (Prince Charles Mountains Expedition of Germany & Australia) expanded research activities to the East Antarctic shield area. In the International Polar Year (IPY), BGR played a leading role in the international project AGAP (Antarctica's GAmburtsev Province) as part of the main topic "Venture into Unknown Regions". AGAP was jointly conducted by the USA, Great Britain, Australia, China and Germany. While in the Ross Sea area even

  16. Environmental radioactivity in the UK: the airborne geophysical view of dose rate estimates.

    PubMed

    Beamish, David

    2014-12-01

    This study considers UK airborne gamma-ray data obtained through a series of high spatial resolution, low altitude surveys over the past decade. The ground concentrations of the naturally occurring radionuclides Potassium, Thorium and Uranium are converted to air absorbed dose rates and these are used to assess terrestrial exposure levels from both natural and technologically enhanced sources. The high resolution airborne information is also assessed alongside existing knowledge from soil sampling and ground-based measurements of exposure levels. The surveys have sampled an extensive number of the UK lithological bedrock formations and the statistical information provides examples of low dose rate lithologies (the formations that characterise much of southern England) to the highest sustained values associated with granitic terrains. The maximum dose rates (e.g. >300 nGy h(-1)) encountered across the sampled granitic terrains are found to vary by a factor of 2. Excluding granitic terrains, the most spatially extensive dose rates (>50 nGy h(-1)) are found in association with the Mercia Mudstone Group (Triassic argillaceous mudstones) of eastern England. Geological associations between high dose rate and high radon values are also noted. Recent studies of the datasets have revealed the extent of source rock (i.e. bedrock) flux attenuation by soil moisture in conjunction with the density and porosity of the temperate latitude soils found in the UK. The presence or absence of soil cover (and associated presence or absence of attenuation) appears to account for a range of localised variations in the exposure levels encountered. The hypothesis is supported by a study of an extensive combined data set of dose rates obtained from soil sampling and by airborne geophysical survey. With no attenuation factors applied, except those intrinsic to the airborne estimates, a bias to high values of between 10 and 15 nGy h(-1) is observed in the soil data. A wide range of

  17. Contribution of the airborne geophysical survey to the study of the regolith : A case study in southern Paris Basin.

    NASA Astrophysics Data System (ADS)

    Prognon, Francois; Lacquement, Fréderic; Deparis, Jacques; Martelet, Guillaume; Perrin, José

    2010-05-01

    Studies of soil and subsoil, also called regolith, are at the crossroads of scientific new challenging questions as well as new environmental needs. Historically, geological maps were focussed on solid geology. Present societal needs increasingly require knowledge of regolith properties: superficial studies combining geology, geochemistry and geophysics become essential to better understand the natural processes which govern the repartition and evolution of subsoil formations. Such progress is critical to better orient the use and management of natural and groundwater resources. Among other techniques, airborne geophysics is appropriate to provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic …). We illustrate the results of an airborne geophysical survey carried out in France, in "Région Centre" administrative region in the southern part of the Paris Basin. Spectral radiometry data were collected throughout "Région Centre" with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. Gamma-rays emitted from the Earth surface are related to the primary mineralogy and geochemistry of the bedrock and/or the nature of secondary weathering including regolith materials. Obtained images are confronted with former geological investigations (1:50 000e geological maps). Geophysical data and geological maps are generally consistent on most of the covered area since the first-rate information delivered by the spectrometry derives from the geochemistry of the solid geology. Second-rate gamma-ray responses come from superimposed allochtonous deposits as well as in situ geochemical modifications. For instance

  18. Monitoring Vadose Zone Desiccation with Geophysical Methods

    SciTech Connect

    Truex, Michael J.; Johnson, Timothy C.; Strickland, Christopher E.; Peterson, John E.; Hubbard, Susan S.

    2013-05-01

    Soil desiccation was recently field tested as a potential vadose zone remediation technology. Desiccation removes water from the vadose zone and significantly decreases the aqueous-phase permeability of the desiccated zone, thereby decreasing movement of moisture and contaminants. The 2-D and 3-D distribution of moisture content reduction over time provides valuable information for desiccation operations and for determining when treatment goals have been reached. This type of information can be obtained through use of geophysical methods. Neutron moisture logging, cross-hole electrical resistivity tomography, and cross-hole ground penetrating radar approaches were evaluated with respect to their ability to provide effective spatial and temporal monitoring of desiccation during a treatability study conducted in the vadose zone of the DOE Hanford Site in WA.

  19. A fractured rock geophysical toolbox method selection tool

    USGS Publications Warehouse

    Day-Lewis, F. D.; Johnson, C.D.; Slater, L.D.; Robinson, J.L.; Williams, J.H.; Boyden, C.L.; Werkema, D.D.; Lane, J.W.

    2016-01-01

    Geophysical technologies have the potential to improve site characterization and monitoring in fractured rock, but the appropriate and effective application of geophysics at a particular site strongly depends on project goals (e.g., identifying discrete fractures) and site characteristics (e.g., lithology). No method works at every site or for every goal. New approaches are needed to identify a set of geophysical methods appropriate to specific project goals and site conditions while considering budget constraints. To this end, we present the Excel-based Fractured-Rock Geophysical Toolbox Method Selection Tool (FRGT-MST). We envision the FRGT-MST (1) equipping remediation professionals with a tool to understand what is likely to be realistic and cost-effective when contracting geophysical services, and (2) reducing applications of geophysics with unrealistic objectives or where methods are likely to fail.

  20. 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.

  1. Airborne Geophysical Surveys Illuminate the Geologic and Hydrothermal Framework of the Pilgrim Springs Geothermal Area, Alaska

    NASA Astrophysics Data System (ADS)

    McPhee, D. K.; Glen, J. M.; Bedrosian, P. A.

    2012-12-01

    An airborne magnetic and frequency-domain electromagnetic (EM) survey of the Pilgrim Springs geothermal area, located on the Seward Peninsula in west-central Alaska, delineates key structures controlling hydrothermal fluid flow. Hot springs, nearby thawed regions, and high lake temperatures are indicative of high heat flow in the region that is thought to be related to recent volcanism. By providing a region-wide geologic and geophysical framework, this work will provide informed decisions regarding drill-site planning and further our understanding of geothermal systems in active extensional basins. Helicopter magnetic and EM data were acquired using a Fugro RESOLVE system equipped with a high sensitivity cesium magnetometer and a multi-coil, multi-frequency EM system sensitive to the frequency range of 400-140,000 Hz. The survey was flown ~40 m above ground along flight lines spaced 0.2-0.4 km apart. Various derivative and filtering methods, including maximum horizontal gradient of the pseudogravity transformation of the magnetic data, are used to locate faults, contacts, and structural domains. A dominant northwest trending anomaly pattern characterizes the northeastern portion of the survey area between Pilgrim Springs and Hen and Chickens Mountain and may reflect basement structures. The area south of the springs, however, is dominantly characterized by east-west trending, range-front-parallel anomalies likely caused by late Cenozoic structures associated with the north-south extension that formed the basin. Regionally, the springs are characterized by a magnetic high punctuated by several east-west trending magnetic lows, the most prominent occurring directly over the springs. The lows may result from demagnetization of magnetic material along range-front parallel features that dissect the basin. We inverted in-phase and quadrature EM data along each profile using the laterally-constrained inversion of Auken et al. (2005). Data were inverted for 20-layer

  2. Magnetotellurics as a multiscale geophysical exploration method

    NASA Astrophysics Data System (ADS)

    Carbonari, Rolando; D'Auria, Luca; Di Maio, Rosa; Petrillo, Zaccaria

    2016-04-01

    Magnetotellurics (MT) is a geophysical method based on the use of natural electromagnetic signals to define subsurface electrical resistivity structure through electromagnetic induction. MT waves are generated in the Earth's atmosphere and magnetosphere by a range of physical processes, such as magnetic storms, micropulsations, lightning activity. Since the underground MT wave propagation is of diffusive type, the longer is the wavelength (i.e. the lower the wave frequency) the deeper will be the propagation depth. Considering the frequency band commonly used in MT prospecting (10-4 Hz to 104 Hz), the investigation depth ranges from few hundred meters to hundreds of kilometers. This means that magnetotellurics is inherently a multiscale method and, thus, appropriate for applications at different scale ranging from aquifer system characterization to petroleum and geothermal research. In this perspective, the application of the Wavelet transform to the MT data analysis could represent an excellent tool to emphasize characteristics of the MT signal at different scales. In this note, the potentiality of such an approach is studied. In particular, we show that the use of a Discrete Wavelet (DW) decomposition of measured MT time-series data allows to retrieve robust information about the subsoil resistivity over a wide range of spatial (depth) scales, spanning up to 5 orders of magnitude. Furthermore, the application of DWs to MT data analysis has proven to be a flexible tool for advanced data processing (e.g. non-linear filtering, denoising and clustering).

  3. Application of geophysical methods to agriculture: An overview

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods are becoming an increasingly valuable tool for agricultural applications. Agricultural geophysics investigations are commonly (although certainly not always) focused on delineating small- and/or large-scale objects/features within the soil profile (~ 0 to 2 m depth) over very lar...

  4. GENERAL CONSIDERATIONS FOR GEOPHYSICAL METHODS APPLIED TO AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysics is the application of physical quantity measurement techniques to provide information on conditions or features beneath the earth’s surface. With the exception of borehole geophysical methods and soil probes like a cone penetrometer, these techniques are generally noninvasive with physica...

  5. Self-Organizing Maps: A Data Mining Tool for the Analysis of Airborne Geophysical Data Collected over the Brazilian Amazon

    NASA Astrophysics Data System (ADS)

    Carneiro, C.; Fraser, S. J.; Crosta, A. P.; Silva, A.; Barros, C.

    2011-12-01

    Regional airborne geophysical data sets are being collected worldwide to promote mineral exploration and resource development. These data sets often are collected over highly prospective terranes, where access is limited or there are environmental concerns. Such regional surveys typically consist of two or more sensor packages being flown in an aircraft over the survey area and vast amounts of near-continuous data can be acquired in a relatively short time. Increasingly, there is also a need to process such data in a timely fashion to demonstrate the data's value and indicate the potential return or value of the survey to the funding agency. To assist in the timely analysis of such regional data sets, we have used an exploratory data mining approach: the Self Organizing Map (SOM). Because SOM is based on vector quantization and measures of vector similarity, it is an ideal tool to analyze a data set consisting of disparate geophysical input parameters to look for relationships and trends. We report on our use of SOM to analyze part of a regional airborne geophysical survey collected over the prospective Anapu-Tuere region of the Brazilian Amazon. Magnetic and spectrometric gamma ray data were used as input to our SOM analysis, and the results used to discriminate and identify various rock types and produce a "pseudo" geological map over the study area. The ability of SOM to define discrete domains of rock-types with similar properties allowed us to expand upon existing geological knowledge of the area for mapping purposes; and, often it was the combination of the magnetic and radiometric responses that identified a lithology's unique response. One particular unit was identified that had an association with known gold mineralization, which consequently highlighted the prospectivity of that unit elsewhere in the survey area. Our results indicate that SOM can be used for the semi-automatic analysis of regional airborne geophysical data to assist in geological mapping

  6. Airborne geophysical survey of ice caps in the Queen Elizabeth Islands, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Palmer, S. J.; Dowdeswell, J. A.; Christoffersen, P.; Benham, T. J.; Young, D. A.; Blankenship, D. D.; Richter, T.; Ng, G.; Grima, C.; Habbal, F.; Sharp, M. J.; Rutishauser, A.

    2014-12-01

    Previous studies have shown that between 2003 and 2009, 60 ± 6 Gt of ice was lost each year from the Canadian Arctic (Gardner et al., 2013), making the region the largest cryospheric contributor to global sea level rise outside of the great ice sheets. Glacier ice in the Queen Elizabeth Islands (QEI) currently covers more than 100,000 km2, representing 20% of Earth's ice-covered land area outside of Greenland and Antarctica. The vast majority of this ice is stored within six ice caps located on Ellesmere, Devon and Axel Heiberg islands. Recent satellite observations of the outlet glaciers draining these ice caps have revealed significant velocity variability on inter-annual and multi-year timescales (Van Wychen et al., 2014), though the drivers of these dynamics are not yet understood. Here we present results obtained in May 2014 during an airborne geophysical survey of the ice caps of Axel Heiberg, Ellesmere and Devon islands, including Agassiz Ice Cap (17,300 km2), Prince of Wales Icefield (19,300 km2) and Devon Ice Cap (14,000 km2). We used a Basler BT-67 aircraft equipped with a suite of geophysical instruments, including a phase-coherent VHF ice-penetrating radar, to measure ice thickness and investigate ice basal conditions along outlet glacier flow lines and in the interior of the ice caps. We reveal that the glaciers draining the ice caps of the QEI exhibit diverse characteristics over short spatial scales, and that fast-flowing tidewater glaciers are located adjacent to previously fast-flowing areas that have subsequently stagnated. Our results show that many ice cap outlet glaciers on Ellesmere and Devon islands are between 700 and 1000 m thick and flow through deep bedrock troughs whose beds lie below sea-level. Some of the outlet glaciers also have floating tongues of ice which extend into the adjacent fjord waters. We intend to use our results to characterize the substrate beneath the ice, and to reveal any variations in conditions at the ice

  7. Geophysics

    NASA Technical Reports Server (NTRS)

    Carr, M. H.; Cassen, P.

    1976-01-01

    Four areas of investigation, each dealing with the measurement of a particular geophysical property, are discussed. These properties are the gravity field, seismicity, magnetism, and heat flow. All are strongly affected by conditions, past or present, in the planetary interior; their measurement is the primary source of information about planetary interiors.

  8. Methods for Sampling of Airborne Viruses

    PubMed Central

    Verreault, Daniel; Moineau, Sylvain; Duchaine, Caroline

    2008-01-01

    Summary: To better understand the underlying mechanisms of aerovirology, accurate sampling of airborne viruses is fundamental. The sampling instruments commonly used in aerobiology have also been used to recover viruses suspended in the air. We reviewed over 100 papers to evaluate the methods currently used for viral aerosol sampling. Differentiating infections caused by direct contact from those caused by airborne dissemination can be a very demanding task given the wide variety of sources of viral aerosols. While epidemiological data can help to determine the source of the contamination, direct data obtained from air samples can provide very useful information for risk assessment purposes. Many types of samplers have been used over the years, including liquid impingers, solid impactors, filters, electrostatic precipitators, and many others. The efficiencies of these samplers depend on a variety of environmental and methodological factors that can affect the integrity of the virus structure. The aerodynamic size distribution of the aerosol also has a direct effect on sampler efficiency. Viral aerosols can be studied under controlled laboratory conditions, using biological or nonbiological tracers and surrogate viruses, which are also discussed in this review. Lastly, general recommendations are made regarding future studies on the sampling of airborne viruses. PMID:18772283

  9. Time-reversal methods in geophysics

    SciTech Connect

    Larmat, Carene S.; Guyer, Robert A.; Johnson, Paul A.

    2010-08-15

    Before the 20th century there were few seismometers. So Earth's dynamic geophysical processes were poorly understood. Today the potential for understanding those processes is enormous: The number of seismic instruments is continually increasing, their data are easily stored and shared, and computing power grows exponentially. As a result, seismologists are rapidly discovering new kinds of seismic signals in the frequency range 0.001-100 Hz, as well as relatively large nonseismic displacements, monitored by the global positioning system, occurring over days or weeks.

  10. Regolith landform mapping based on remote sensing data and airborne geophysics in Western Burkina Faso

    NASA Astrophysics Data System (ADS)

    Metelka, Vaclav; Baratoux, Lenka; Jessell, Mark; Naba, Seta

    2010-05-01

    The Precambrian granite-greenstone belts of West Africa are currently of great interest both to scientific community as well as the exploration industry. Studying and observing the geology of these ancient terrains is not an easy task mainly due to complex, deep weathering, which effectively masks the underlying bedrock. It is the weathered regolith material and its landforms that can be directly accessed by surface mapping. Knowing the distribution of these regolith landform units and understanding the processes which led to their formation is crucial for any kind of successful geological mapping or geochemical exploration project. In our research we have focused on regolith units in the Houndé and Boromo greenstone belts in Western Burkina Faso. We examined three approaches to map regolith material and subsequently regolith landform units: subpixel classification, based on spectral characteristics of indicative materials, a polarimetric segmentation of radar data, and a classification of an integrated dataset of remote sensing data and airborne gamma-ray spectrometry data. In situ spectral measurements were used to calibrate ASTER and LANDSAT scenes and served as endmember identifiers. A spectral library has been created containing over three hundred unique spectral measurements. ASTER and Landsat data were classified using the Mixture tuned matched filtering method. Wishart supervised classifier was used on ALOS PALSAR data. Classifications based on supervised maximum likelihood method and neural networks have been applied to an integrated dataset which included SRTM elevation data and airborne gamma-ray spectrometry. Feruginous duricrusts rich in hematite and goethite, clay rich mottled zones relics and fluvial sediments were mapped successfully in the region. The results were compared with existing regolith landform maps and field observations.

  11. Interpretation of an airborne geophysical survey in southern Paris Basin: towards a lithological cartography, key tool for the management of shrinking/swelling clay problems

    NASA Astrophysics Data System (ADS)

    Prognon, F.; Tourliere, B.; Perrin, J.; Lacquement, F.; Martelet, G.; Deparis, J.; Gourdier, S.; Drufin, S.

    2011-12-01

    Regolith formations support a full spectrum of human activities. Among others, they provide a source of extractable materials and form the substratum of soils. As such, they should be considered as a capital to be managed and protected. Moreover, one of the main challenges for present and future land settlement is to prevent house building programs from being planned inside shrink-swell risky areas which is only possible thanks to an complete lithological mapping of the french regolith. We illustrate here the results of the geological interpretation of an airborne geophysical survey carried out in "Région Centre" administrative region in the southern part of the Paris Basin, in France. Among other techniques, airborne geophysics is appropriate to quickly provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic...). Spectral radiometry data were collected with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. On the radiometric data we applied the HAC (Hierarchical Ascendant Classification) computation procedure: taking into account several variables, the statistical HAC method groups individuals based on their resemblance. Also in this study, calibrated Total Count channel (TCm) is compared to an estimated dose rate (TCe) computed from the measured radioelement abundances: TCe = 13.078 * K + 5.675 * U + 2.494 * Th. Our results show that the ratio TCe/TCm came out to be a good indicator of ground property changes within Sologne mixed sandy-clay environment. Processed geophysical data are cross-checked with geological data (from field observations) and field or laboratory measurements of mineralogical data

  12. Remote sensing and airborne geophysics in the assessment of natural aggregate resources

    USGS Publications Warehouse

    Knepper, D.H.; Langer, W.H.; Miller, S.H.

    1994-01-01

    Natural aggregate made from crushed stone and deposits of sand and gravel is a vital element of the construction industry in the United States. Although natural aggregate is a high volume/low value commodity that is relatively abundant, new sources of aggregate are becoming increasingly difficult to find and develop because of rigid industry specifications, political considerations, development and transporation costs, and environmental concerns, especially in urban growth centers where much of the aggregate is used. As the demand for natural aggregate increases in response to urban growth and the repair and expansion of the national infrastructure, new sources of natural aggregate will be required. The USGS has recognized the necessity of developing the capability to assess the potential for natural aggregate sources on Federal lands; at present, no methodology exists for systematically describing and evaluating potential sources of natural aggregate. Because remote sensing and airborne geophysics can detect surface and nearsurface phenomena, these tools may useful for detecting and mapping potential sources of natural aggregate; however, before a methodology for applying these tools can be developed, it is necessary to understand the type, distribution, physical properties, and characteristics of natural aggregate deposits, as well as the problems that will be encountered in assessing their potential value. There are two primary sources of natural aggregate: (1) exposed or near-surface igneous, metamorphic, and sedimentary bedrock that can be crushed, and (2) deposits of sand and gravel that may be used directly or crushed and sized to meet specifications. In any particular area, the availability of bedrock suitable for crushing is a function of the geologic history of the area - the processes that formed, deformed, eroded and exposed the bedrock. Deposits of sand and gravel are primarily surficial deposits formed by the erosion, transportation by water and ice

  13. A Simple Method for Collecting Airborne Pollen

    ERIC Educational Resources Information Center

    Kevan, Peter G.; DiGiovanni, Franco; Ho, Rong H.; Taki, Hisatomo; Ferguson, Kristyn A.; Pawlowski, Agata K.

    2006-01-01

    Pollination is a broad area of study within biology. For many plants, pollen carried by wind is required for successful seed set. Airborne pollen also affects human health. To foster studies of airborne pollen, we introduce a simple device--the "megastigma"--for collecting pollen from the air. This device is flexible, yielding easily obtained data…

  14. Well casing-based geophysical sensor apparatus, system and method

    DOEpatents

    Daily, William D.

    2010-03-09

    A geophysical sensor apparatus, system, and method for use in, for example, oil well operations, and in particular using a network of sensors emplaced along and outside oil well casings to monitor critical parameters in an oil reservoir and provide geophysical data remote from the wells. Centralizers are affixed to the well casings and the sensors are located in the protective spheres afforded by the centralizers to keep from being damaged during casing emplacement. In this manner, geophysical data may be detected of a sub-surface volume, e.g. an oil reservoir, and transmitted for analysis. Preferably, data from multiple sensor types, such as ERT and seismic data are combined to provide real time knowledge of the reservoir and processes such as primary and secondary oil recovery.

  15. Applied high resolution geophysical methods: Offshore geoengineering hazards

    SciTech Connect

    Trabant, P.K.

    1984-01-01

    This book is an examination of the purpose, methodology, equipment, and data interpretation of high-resolution geophysical methods, which are used to assess geological and manmade engineering hazards at offshore construction locations. It is a state-of-the-art review. Contents: 1. Introduction. 2. Maring geophysics, an overview. 3. Marine geotechnique, an overview. 4. Echo sounders. 5. Side scan sonar. 6. Subbottom profilers. 7. Seismic sources. 8. Single-channel seismic reflection systems. 9. Multifold acquisition and digital processing. 10. Marine magnetometers. 11. Marine geoengineering hazards. 12. Survey organization, navigation, and future developments. Appendix. Glossary. References. Index.

  16. Autonomous and Remote-Controlled Airborne and Ground-Based Robotic Platforms for Adaptive Geophysical Surveying

    NASA Astrophysics Data System (ADS)

    Spritzer, J. M.; Phelps, G. A.

    2011-12-01

    Low-cost autonomous and remote-controlled robotic platforms have opened the door to precision-guided geophysical surveying. Over the past two years, the U.S. Geological Survey, Senseta, NASA Ames Research Center, and Carnegie Mellon University Silicon Valley, have developed and deployed small autonomous and remotely controlled vehicles for geophysical investigations. The purpose of this line of investigation is to 1) increase the analytical capability, resolution, and repeatability, and 2) decrease the time, and potentially the cost and map-power necessary to conduct near-surface geophysical surveys. Current technology has advanced to the point where vehicles can perform geophysical surveys autonomously, freeing the geoscientist to process and analyze the incoming data in near-real time. This has enabled geoscientists to monitor survey parameters; process, analyze and interpret the incoming data; and test geophysical models in the same field session. This new approach, termed adaptive surveying, provides the geoscientist with choices of how the remainder of the survey should be conducted. Autonomous vehicles follow pre-programmed survey paths, which can be utilized to easily repeat surveys on the same path over large areas without the operator fatigue and error that plague man-powered surveys. While initial deployments with autonomous systems required a larger field crew than a man-powered survey, over time operational experience costs and man power requirements will decrease. Using a low-cost, commercially available chassis as the base for autonomous surveying robotic systems promise to provide higher precision and efficiency than human-powered techniques. An experimental survey successfully demonstrated the adaptive techniques described. A magnetic sensor was mounted on a small rover, which autonomously drove a prescribed course designed to provide an overview of the study area. Magnetic data was relayed to the base station periodically, processed and gridded. A

  17. Geophysical Methods for Investigating Ground-Water Recharge

    USGS Publications Warehouse

    Ferre, Ty P.A.; Binley, Andrew M.; Blasch, Kyle W.; Callegary, James B.; Crawford, Steven M.; Fink, James B.; Flint, Alan L.; Flint, Lorraine E.; Hoffmann, John P.; Izbicki, John A.; Levitt, Marc T.; Pool, Donald R.; Scanlon, Bridget R.

    2007-01-01

    While numerical modeling has revolutionized our understanding of basin-scale hydrologic processes, such models rely almost exclusively on traditional measurements?rainfall, streamflow, and water-table elevations?for calibration and testing. Model calibration provides initial estimates of ground-water recharge. Calibrated models are important yet crude tools for addressing questions about the spatial and temporal distribution of recharge. An inverse approach to recharge estimation is taken of necessity, due to inherent difficulties in making direct measurements of flow across the water table. Difficulties arise because recharging fluxes are typically small, even in humid regions, and because the location of the water table changes with time. Deep water tables in arid and semiarid regions make recharge monitoring especially difficult. Nevertheless, recharge monitoring must advance in order to improve assessments of ground-water recharge. Improved characterization of basin-scale recharge is critical for informed water-resources management. Difficulties in directly measuring recharge have prompted many efforts to develop indirect methods. The mass-balance approach of estimating recharge as the residual of generally much larger terms has persisted despite the use of increasing complex and finely gridded large-scale hydrologic models. Geophysical data pertaining to recharge rates, timing, and patterns have the potential to substantially improve modeling efforts by providing information on boundary conditions, by constraining model inputs, by testing simplifying assumptions, and by identifying the spatial and temporal resolutions needed to predict recharge to a specified tolerance in space and in time. Moreover, under certain conditions, geophysical measurements can yield direct estimates of recharge rates or changes in water storage, largely eliminating the need for indirect measures of recharge. This appendix presents an overview of physically based, geophysical methods

  18. OPTIMIZING THE PAKS METHOD FOR MEASURING AIRBORNE ACROLEIN

    EPA Science Inventory

    Airborne acrolein is produced from the combustion of fuel and tobacco and is of concern due to its potential for respiratory tract irritation and other adverse health effects. DNPH active-sampling is a method widely used for sampling airborne aldehydes and ketones (carbonyls); ...

  19. 59 FR- Method Development for Airborne Mycobacterium Tuberculosis; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    1994-03-07

    ... Tuberculosis; Meeting The National Institute for Occupational Safety and Health (NIOSH) of the Centers for... Airborne Mycobacterium Tuberculosis. Time and Date: 1 p.m.-5 p.m., March 29, 1994. Place: Alice Hamilton... peer review of a NIOSH project entitled ``Method Development For Airborne Mycobacterium...

  20. Hydrogeological-Geophysical Methods for Subsurface Site Characterization - Final Report

    SciTech Connect

    Rubin, Yoram

    2001-01-01

    The goal of this research project is to increase water savings and show better ecological control of natural vegetation by developing hydrogeological-geophysical methods for characterizing the permeability and content of water in soil. The ground penetrating radar (GPR) tool was developed and used as the surface geophysical method for monitoring water content. Initial results using the tool suggest that surface GPR is a viable technique for obtaining precision volumetric water content profile estimates, and that laboratory-derived petrophysical relationships could be applied to field-scale GPR data. A field-scale bacterial transport study was conducted within an uncontaminated sandy Pleistocene aquifer to evaluate the importance of heterogeneity in controlling the transport of bacteria. Geochemical, hydrological, geological, and geophysical data were collected to characterize the site prior to and after chemical and bacterial injection experiments. Study results shows that, even within the fairly uniform shallow marine deposits of the narrow channel focus area, heterogeneity existed that influenced the chemical tracer transport over lateral distances of a few meters and vertical distances of less than a half meter. The interpretation of data suggest that the incorporation of geophysical data with limited hydrological data may provide valuable information about the stratigraphy, log conductivity values, and the spatial correlation structure of log conductivity, which have traditionally been obtainable only by performing extensive and intrusive hydrological sampling.

  1. New geological and tectonic map of Paleoproterozoic basement in western Burkina Faso: integrated interpretation of airborne geophysical and field data

    NASA Astrophysics Data System (ADS)

    Metelka, Vaclav; Baratoux, Lenka; Jessell, Mark; Naba, Seta

    2010-05-01

    The recent acquisition of regional scale airborne datasets over most of the West African craton sparked off a number of studies concentrating on their litho-tectonic interpretation. In such polydeformed terrains, where outcrop is very sparse or virtually nonexistent due to the presence of thick lateritic cover, geophysics and specifically geomagnetic surveying provide a wealth of information that facilitates the deciphering of regional litho-structural hierarchies. A revised geological and tectonic map of the Houndé and Boromo greenstone belts was derived by interpretation of aeromagnetic and gamma-ray spectrometric data constrained by field observations where available. Medium resolution geophysical data gridded at 250 meters acquired during the SYSMIN project served as a basis for the interpretation. This dataset was integrated with the SRTM digital elevation model and over 600 field observations. Furthermore, the BRGM/BUMIGEB SYSMIN project outcrops database (Castaing et al., 2003) as well as older outcrop maps, maintained by BUMIGEB, were used. Locally, outcrop maps and high resolution geophysics provided by mining companies (Orezone, SEMAFO, Volta Resources, Wega Mining) were employed. 2-D geophysical inversion modeling in GM-sys software using the ground gravity and airborne magnetic data was applied to three selected E-W profiles. Principal component analysis (PCA) of magnetic and radiometric data was a powerful tool for distinguishing different lithological units, in particular tholeiitic suites of basalts and gabbros and various volcano-sedimentary units. Some of the granite pluton limits can be traced as well using the PCA; however thick lateritic cover substantially hinders precise mapping. Magnetic data used on its own gave better results not only for granite limits but also for determining internal structures such as shear zones and concentric compositional zoning. Several major N-S to NNE-SSW oriented shear zones, representing most probably deep

  2. Airborne Geophysics and Remote Sensing Applied to Study Greenland Ice Dynamics

    NASA Technical Reports Server (NTRS)

    Csatho, Beata M.

    2003-01-01

    Overview of project: we combined and jointly analysed geophysical, remote sensing and glaciological data for investigating the temporal changes in ice flow and the role of geologic control on glacial drainage. The project included two different studies, the investigation of recent changes of the Kangerlussuaq glacier and the study of geologic control of ice flow in NW Greenland, around the Humboldt, Petermann and Ryder glaciers.

  3. Forward modeling of geophysical electromagnetic methods using Comsol

    NASA Astrophysics Data System (ADS)

    Butler, S. L.; Zhang, Z.

    2016-02-01

    In geophysical electromagnetic methods, time-varying magnetic fields are measured at Earth's surface that are produced by electrical currents inside the Earth in order to constrain subsurface conductivity and geological structure. These methods are widely used for mineral exploration and environmental investigations, and are increasingly being used in hydrocarbon exploration as well. Forward modeling of exploration geophysics methods is useful for the purpose of survey planning, for understanding the method, especially for students, and as part of an iteration process in inverting measured data. Modeling electromagnetic methods remains an area of active research. In most geophysical methods, the electromagnetic frequency is sufficiently low that the wavelength of the radiation is much larger than the area of interest. As such, the quasi-static approximation is valid. Comsol Multiphysics' AC/DC module solves Maxwell's equations in the quasi-static approximation and in this contribution, we will show examples of its use in modeling magnetometric resistivity (MMR), very low frequency (VLF) techniques, as well as frequency and time-domain induction-based electromagnetic techniques. Solutions are compared with benchmarks from the literature.

  4. Application of geophysical methods for environmental control in mining areas

    SciTech Connect

    Mueller, K.; Muellerova, J.; Hofrichterova, L.

    1994-12-31

    In areas affected by mining operations, a variety of methods ar necessary to acquire information for making decisions related to environmental protection. Of great importance are geophysical methods to collect data about: seismic activity and seismic hazard in the area of interest; radon risk; damage to rock massif resulting from mining operations and development of subsidence depression as mining advances; inhomogeneities in compactness of gangue fills and defects in dams and roadbeds; and hydrodynamic changes and contamination of groundwater. The importance of geophysical methods has increased recently, particularly as applied to monitoring or to the repeatable measurement-variant on fixed points. In the Ostrava-Karvina Coal Basin, a seismic station of the first range OKP was built in 1980. Between 1986 and 1990, the regional diagnostic polygon was established, involving 10 three-component stations uniformly distributed throughout the Ostrava-Karvina Basin that allows seismic activity--both natural and, particularly, that induced by mining operations--to be monitored continuously. Analysis of seismic events related to the advance of mining and to engineering and geological conditions enabled researchers to develop a seismic hazard map for surface facilities. This map is useful for design purposes and for making decisions related to maintenance and damages. Emanation measurements, together with other geophysical methods (e.g., resistivity, seismic, acoustic, and thermic measurements), are utilized to determine stability conditions in the area and to observe development of subsidence depressions and slope deformations. Some of the results from these surveys are given.

  5. Apparatus and method for automated monitoring of airborne bacterial spores

    NASA Technical Reports Server (NTRS)

    Ponce, Adrian (Inventor)

    2009-01-01

    An apparatus and method for automated monitoring of airborne bacterial spores. The apparatus is provided with an air sampler, a surface for capturing airborne spores, a thermal lysis unit to release DPA from bacterial spores, a source of lanthanide ions, and a spectrometer for excitation and detection of the characteristic fluorescence of the aromatic molecules in bacterial spores complexed with lanthanide ions. In accordance with the method: computer-programmed steps allow for automation of the apparatus for the monitoring of airborne bacterial spores.

  6. A Research of the Application Geophysical Methods to the Polluted Site and the river bottom mud in Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Cheng, S.; Liu, H. C.

    2013-12-01

    Many site investigations have found that DNAPL is able to penetrate the low permeable layer such as clay or silt-caly layer in subsurface environment. The cumulated DNAPL within the low permeable Layer will gradually diffuse to the high permeable layer to affect he accuracy of investigation and remedial design. As to the deeper zone affected by the penetration of DNAPL, the conventional sampling design investigating only the first unconfined aquifer is no longer suitable for DNAPL investigation. Precisely define the boundary and the distribution of high and low permeable layer is the key to conduct a successful DNAPL investigation. Point information derived from the conventional bore-hole sampling is difficult to be used for locating the DNAPL pollution due to the uncertainty of DNAPL migration and the soluble-phase distribution of the DNAPL partitioned into ground water between the low and high permeable layer. Recently, non-invaded technologies such as geophysical technology have been introduced to provide the plane and space information of pollution in subsurface by integrating few bore-hole dates. The most common used geophysical technologies are ground-penetrating radar method (GPR) and electrical resistivity tomography (ERT). Both methods have their limitations on the pollution investigation when there are interferences exist such as building structure or heavy pavement. A new geophysical technology, geophysical well logging has been developed to overcome above limitations. The information of multi-wells logging could be used to interpret the permeability of subsurface, the dominate flow path and the hot-spot for evaluating the distribution of pollution and the efficiency of remediation in different time sequences. This study would first discuss how DNAPL and its soluble-phase components invade into the low permeable layer based on the field observation. Then, the importance of geophysical technology is introduced with comparing to the limitations of bore

  7. Airborne gravity and other geophysical techniques for understanding the lithosphere beneath the West Antarctic Ice Sheet

    NASA Technical Reports Server (NTRS)

    Bell, Robin E.; Blankenship, Donald D.; Hodge, Steven M.; Brozena, John M.; Behrendt, John C.

    1993-01-01

    As part of a program entitled Corridor Aerogeophysics of the Southeastern Ross Transect Zone (CASERTZ), an aerogeophysical platform was developed to study the interaction of geological and glaciological processes in West Antarctica. A de Havilland Twin Otter was equipped with an ice-penetrating radar, a proton precession magnetometer, an airborne gravity system, and a laser altimeter. The 60-MHz ice-penetrating radar can recover sub-ice topography with an accuracy of about 10 m through 3 km of comparatively warm West Antarctic ice, while the laser altimeter profiling of the ice surface is accurate to approximately 1 m. The magnetic field observations are accurate to several nT, and the gravity measurements are accurate to better than 3 mGal. The aircraft is navigated by a local radio transponder network, while differential positioning techniques based on the Global Positioning System (GPS) satellites are used for recovering high-resolution horizontal and vertical positions. Attitude information from an inertial navigation system is used to correct the laser altimetry and a digital pressure transducer is used to recover vertical positions and accelerations in the absence of satellite positioning. Continuous base-station observations are made for the differential GPS positioning and the removal of ionospheric noise from the airborne magnetometer measurements.

  8. Geophysics-based method of locating a stationary earth object

    DOEpatents

    Daily, Michael R.; Rohde, Steven B.; Novak, James L.

    2008-05-20

    A geophysics-based method for determining the position of a stationary earth object uses the periodic changes in the gravity vector of the earth caused by the sun- and moon-orbits. Because the local gravity field is highly irregular over a global scale, a model of local tidal accelerations can be compared to actual accelerometer measurements to determine the latitude and longitude of the stationary object.

  9. Geophysical methods application in groundwater natural protection against pollution

    NASA Astrophysics Data System (ADS)

    Komatina, S. M.

    1994-02-01

    Natural protection against groundwater pollution mostly depends on water-bearing bed coverage with permeable rocks presenting a good or bad pollution intrusion barrier between the surface and subterranean water. Additional positive effects of polluted groundwater self-purification in these zones are visible. Natural protection from surface pollutants primarily depends on natural (geological) factors: (1) presence of poorly permeable rocks; (2) depth, lithology (grain-size distribution), and filtration features of rocks covering groundwater reservoirs; and (3) aquifer depth. In contrast to artesian aquifers, quantitative and qualitative evaluation for natural protection of intergranular aquifers with a free water surface is significantly complicated. In this case, the estimation is possible with the help of a specially developed statistical method, which requires the following elements referring to the zone of aeration: (1) poorly permeable strata depth; (2) filtration features; (3) groundwater level depth; and (4) lithology. For quantitative evaluation, it is necessary to know the time interval for pollution propagating from surface of the terrain to the free water surface. Describe access is particularly useful in the domain of zones of sanitary protection defined around the source of groundwater. This exploration method could be considerably rationalized by geophysical methods application. Various methods are useful, namely: electric mapping and sounding, self-potential method, seismic reflection and refraction methods, gravity and geomagnetic methods, the “turam” method, and different well-logging measurements (gamma ray, gammagamma, radioactivity log, and thermal log). In the paper, geophysical methods applictations in natural protection against groundwater pollution and appropriate critical analysis are presented. The results of this paper are based on the experience and application of geophysical methods to groundwater studies in Yugoslavia by the author.

  10. High spatial resolution observations of 137Cs in northern Britain and Ireland from airborne geophysical survey.

    PubMed

    Scheib, Cathy; Beamish, David

    2010-09-01

    This study reports the (137)Cs data derived from three regional and national scale High Resolution Airborne Resource and Environmental Surveys (HiRES) in northern Britain and Ireland. The detailed spatial resolution, combined with the large areas these surveys collectively cover, gives insight into large-scale deposition patterns and possible subsequent re-distribution of (137)Cs on a level that was previously not possible. The largest survey area considered covers the whole of Northern Ireland. All three data sets display some clustering of higher (137)Cs activities on high ground together with regional scale NNW-SSE and NW-SE banding features. We interpret these as representing a series of rainfall interceptions of the repeated passage of the Chernobyl plume. Our observations, obtained at 200 m flight line intervals, appear to provide significant detail in relation to existing knowledge of large scale along-wind deposition of (137)Cs.

  11. Porosity and Dissolved Salt Load Estimation from Geophysical Airborne Em and Borehole EC

    NASA Astrophysics Data System (ADS)

    Ley-Cooper, Y.; Macnae, J.; Tweed, S.

    2006-12-01

    Dissolved salt in aquifers can be a hazard to fresh water resources. Interpolated grid maps at the depth of the aquifer, derived from EC measurements on borehole water samples, can be combined with more detailed bulk electrical conductivities from airborne electromagnetics to provide detailed predictions of subsurface porosity and total dissolved salt load. The calculated porosity and salt load are in fact maximum estimate values since a resistive host matrix is assumed. The technique has been applied to vertically distinct aquifers in two different areas of the salt-threatened Murray-Darling basin in Australia. This technique may provide extensive information on the hydraulic properties of aquifers, has important implications for quantitative hydrological models, particularly in estimations of sustainable groundwater use, and timeframes for saline groundwater migration

  12. Airborne electromagnetic data and processing within Leach Lake Basin, Fort Irwin, California: Chapter G in Geology and geophysics applied to groundwater hydrology at Fort Irwin, California

    USGS Publications Warehouse

    Bedrosian, Paul A.; Ball, Lyndsay B.; Bloss, Benjamin R.

    2014-01-01

    From December 2010 to January 2011, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of Leach Lake Basin within the National Training Center, Fort Irwin, California. These data were collected to characterize the subsurface and provide information needed to understand and manage groundwater resources within Fort Irwin. A resistivity stratigraphy was developed using ground-based time-domain electromagnetic soundings together with laboratory resistivity measurements on hand samples and borehole geophysical logs from nearby basins. This report releases data associated with the airborne surveys, as well as resistivity cross-sections and depth slices derived from inversion of the airborne electromagnetic data. The resulting resistivity models confirm and add to the geologic framework, constrain the hydrostratigraphy and the depth to basement, and reveal the distribution of faults and folds within the basin.

  13. Regional Characterization of Soil Properties via a Combination of Methods from Remote Sensing, Geophysics and Geopedology

    NASA Astrophysics Data System (ADS)

    Meyer, Uwe; Fries, Elke; Frei, Michaela

    2016-04-01

    Soil is one of the most precious resources on Earth. Preserving, using and enriching soils are most complex processes that fundamentally need a sound regional data base. Many countries lack this sort of extensive data or the existing data must be urgently updated when land use recently changed in major patterns. The project "RECHARBO" (Regional Characterization of Soil Properties) aims at the combination of methods from remote sensing, geophysics and geopedology in order to develop a new system to map soils on a regional scale in a quick and efficient manner. First tests will be performed on existing soil monitoring districts, using newly available sensing systems as well as established techniques. Especially hyperspectral and infrared data measured from satellites or airborne platforms shall be combined. Moreover, a systematic correlation between hyperspectral imagery and gamma-ray spectroscopy shall be established. These recordings will be compared and correlated to measurements upon ground and on soil samples to get hold of properties such as soil moisture, soil density, specific resistance plus analytic properties like clay content, anorganic background, organic matter etc. The goal is to generate a system that enables users to map soil patterns on a regional scale using airborne or satellite data and to fix their characteristics with only a limited number of soil samples.

  14. Non-Destructive Survey of Archaeological Sites Using Airborne Laser Scanning and Geophysical Applications

    NASA Astrophysics Data System (ADS)

    Poloprutský, Z.; Cejpová, M.; Němcová, J.

    2016-06-01

    This paper deals with the non-destructive documentation of the "Radkov" (Svitavy district, Czech Republic) archaeological site. ALS, GPR and land survey mapping will be used for the analysis. The fortified hilltop settlement "Radkov" is an immovable historical monument with preserved relics of anthropogenic origin in relief. Terrain reconnaissance can identify several accentuated objects on site. ALS enables identification of poorly recognizable archaeological objects and their contexture in the field. Geophysical survey enables defunct objects identification. These objects are hidden below the current ground surface and their layout is crucial. Land survey mapping provides technical support for ALS and GPR survey. It enables data georeferencing in geodetic reference systems. GIS can then be used for data analysis. M. Cejpová and J. Němcová have studied this site over a long period of time. In 2012 Radkov was surveyed using ALS in the project "The Research of Ancient Road in Southwest Moravia and East Bohemia". Since 2015 the authors have been examining this site. This paper summarises the existing results of the work of these authors. The digital elevation model in the form of a grid (GDEM) with a resolution 1 m of 2012 was the basis for this work. In 2015 the survey net, terrain reconnaissance and GPR survey of two archaeological objects were done at the site. GDEM was compared with these datasets. All datasets were processed individually and its results were compared in ArcGIS. This work was supported by the Grant Agency of the CTU in Prague, grant No. SGS16/063/OHK1/1T/11.

  15. Combination of Geophysical Methods to Support Urban Geological Mapping

    NASA Astrophysics Data System (ADS)

    Gabàs, A.; Macau, A.; Benjumea, B.; Bellmunt, F.; Figueras, S.; Vilà, M.

    2014-07-01

    Urban geological mapping is a key to assist management of new developed areas, conversion of current urban areas or assessment of urban geological hazards. Geophysics can have a pivotal role to yield subsurface information in urban areas provided that geophysical methods are capable of dealing with challenges related to these scenarios (e.g., low signal-to-noise ratio or special logistical arrangements). With this principal aim, a specific methodology is developed to characterize lithological changes, to image fault zones and to delineate basin geometry in the urban areas. The process uses the combination of passive and active techniques as complementary data: controlled source audio-magnetotelluric method (CSAMT), magnetotelluric method (MT), microtremor H/V analysis and ambient noise array measurements to overcome the limitations of traditional geophysical methodology. This study is focused in Girona and Salt surrounding areas (NE of Spain) where some uncertainties in subsurface knowledge (maps of bedrock depth and the isopach maps of thickness of quaternary sediments) need to be resolved to carry out the 1:5000 urban geological mapping. These parameters can be estimated using this proposed methodology. (1) Acoustic impedance contrast between Neogene sediments and Paleogene or Paleozoic bedrock is detected with microtremor H/V analysis that provides the soil resonance frequency. The minimum value obtained is 0.4 Hz in Salt city, and the maximum value is the 9.5 Hz in Girona city. The result of this first method is a fast scanner of the geometry of basement. (2) Ambient noise array constrains the bedrock depth using the measurements of shear-wave velocity of soft soil. (3) Finally, the electrical resistivity models contribute with a good description of lithological changes and fault imaging. The conductive materials (1-100 Ωm) are associated with Neogene Basin composed by unconsolidated detrital sediments; medium resistive materials (100-400 Ωm) correspond to

  16. Dynamics and internal structure of an Alaskan debris-covered glacier from repeat airborne photogrammetry and surface geophysics

    NASA Astrophysics Data System (ADS)

    Holt, John; Levy, Joseph; Petersen, Eric; Larsen, Chris; Fahnestock, Mark

    2016-04-01

    Debris-covered glaciers and rock glaciers encompass a range of compositions and activity, and can be useful paleoclimate indicators. They also respond differently to ongoing climate change than glaciers without a protective cover. Their flow dynamics are not well understood, and their unique surface morphologies, including lobate fronts and arcuate ridges, likely result from viscous flow influenced by a combination of composition, structure, and climatic factors. However, basic connections between flow kinematics and surface morphology have not yet been established, limiting our ability to understand these features. In order to begin to address this problem we have undertaken airborne and surface studies of multiple debris-covered glaciers in Alaska and the western U.S. Sourdough Rock Glacier in the St. Elias Mountains, Alaska, is completely debris-covered and exhibits numerous transverse compressional ridges. Its trunk also exhibits highly regular bumps and swales with a wavelength of ~175 m and amplitudes up to 12 m. In the middle trunk, lineations (boulder trains and furrows) bend around a point roughly 200m from the eastern edge. We acquired five high-resolution airborne surveys of Sourdough Rock Glacier between late 2013 and late 2015 using lidar and photogrammetry to assess annual and seasonal change at the sub-meter level. Differencing the DTMs provides vertical change while feature tracking in orthophotos provide horizontal velocities that indicate meters of annual motion. The flow field is highly correlated with surface features; in particular, compressional ridges in the lower lobe. Stranded, formerly active lobes are also apparent. Surface geophysical studies were undertaken to constrain internal structure and composition using a combination of ground-penetrating radar (GPR) at 50 and 100 MHz in six transects, and time-domain electromagnetic (TDEM) measurements at 47 locations, primarily in an along-flow transect and two cross-flow transects. We infer

  17. Geophysical Methods for Non-Destructive Testing in Civil Engineering

    NASA Astrophysics Data System (ADS)

    Niederleithinger, E.

    2013-12-01

    Many non-destructive testing (NDT) methods for civil engineering (e. g. ultrasonics, radar) are similar to geophysical techniques. They just differ in scale, material under investigation and vocabulary used. In spite of the fact that the same principles of physics and mathematics apply to both fields, exchange has been limited in the past. But since a few years more and more geophysical knowledge is used in civil engineering. One of the focal points in research is to improve ultrasonic testing of concrete to be able to image the inside even of large, complex structures and to detect any deterioration as early as possible. One of the main issues is the heterogeneity of concrete, including aggregates, reinforcement, cracks and many other features. Our current research focuses on three points. One is the application of state of the art geophysical migration techniques as Reverse Time Migration (RTM) to image vertical faces or the backside of voids and ducts in thick concrete structures, which isn't possible with conventional techniques used in NDT. Second, we have started to use seismic interferometric techniques to interpolate ultrasonic traces, which can't be measured directly for technical reasons. Third, we are using coda wave interferometry to detect concrete degradation due to load, fatigue, temperature or other influences as early as possible. Practical examples of the application of these techniques are given and potential future research directions will be discussed. It will be shown, how a subset of these techniques can be used for innovative monitoring systems for civil infrastructure. Imaging the interior of a concrete body by ultrasonics and reverse time migration(simulated data).

  18. Multivariate approximation methods and applications to geophysics and geodesy

    NASA Technical Reports Server (NTRS)

    Munteanu, M. J.

    1979-01-01

    The first report in a series is presented which is intended to be written by the author with the purpose of treating a class of approximation methods of functions in one and several variables and ways of applying them to geophysics and geodesy. The first report is divided in three parts and is devoted to the presentation of the mathematical theory and formulas. Various optimal ways of representing functions in one and several variables and the associated error when information is had about the function such as satellite data of different kinds are discussed. The framework chosen is Hilbert spaces. Experiments were performed on satellite altimeter data and on satellite to satellite tracking data.

  19. Expedited Site Characterization geophysics: Geophysical methods and tools for site characterization

    SciTech Connect

    Goldstein, N.E.

    1994-03-01

    This report covers five classes of geophysical technologies: Magnetics; Electrical/electromagnetic; Seismic reflection; Gamma-ray spectrometry; and Metal-specific spectrometry. Except for radiometry, no other classes of geophysical tedmologies are specific for direct detection of the types of contaminants present at the selected sites. For each of the five classes covered, the report gives a general description of the methodology, its field use, and its general applicability to the ESC Project. In addition, the report gives a sample of the most promising instruments available for each class, including the following information: Hardware/software attributes; Purchase and rental costs; Survey rate and operating costs; and Other applicable information based on case history and field evaluations.

  20. Space-time adaptive numerical methods for geophysical applications.

    PubMed

    Castro, C E; Käser, M; Toro, E F

    2009-11-28

    In this paper we present high-order formulations of the finite volume and discontinuous Galerkin finite-element methods for wave propagation problems with a space-time adaptation technique using unstructured meshes in order to reduce computational cost without reducing accuracy. Both methods can be derived in a similar mathematical framework and are identical in their first-order version. In their extension to higher order accuracy in space and time, both methods use spatial polynomials of higher degree inside each element, a high-order solution of the generalized Riemann problem and a high-order time integration method based on the Taylor series expansion. The static adaptation strategy uses locally refined high-resolution meshes in areas with low wave speeds to improve the approximation quality. Furthermore, the time step length is chosen locally adaptive such that the solution is evolved explicitly in time by an optimal time step determined by a local stability criterion. After validating the numerical approach, both schemes are applied to geophysical wave propagation problems such as tsunami waves and seismic waves comparing the new approach with the classical global time-stepping technique. The problem of mesh partitioning for large-scale applications on multi-processor architectures is discussed and a new mesh partition approach is proposed and tested to further reduce computational cost.

  1. Integrated Geophysical Methods Applied to Geotechnical and Geohazard Engineering: From Qualitative to Quantitative Analysis and Interpretation

    NASA Astrophysics Data System (ADS)

    Hayashi, K.

    2014-12-01

    The Near-Surface is a region of day-to-day human activity on the earth. It is exposed to the natural phenomena which sometimes cause disasters. This presentation covers a broad spectrum of the geotechnical and geohazard ways of mitigating disaster and conserving the natural environment using geophysical methods and emphasizes the contribution of geophysics to such issues. The presentation focusses on the usefulness of geophysical surveys in providing information to mitigate disasters, rather than the theoretical details of a particular technique. Several techniques are introduced at the level of concept and application. Topics include various geohazard and geoenvironmental applications, such as for earthquake disaster mitigation, preventing floods triggered by tremendous rain, for environmental conservation and studying the effect of global warming. Among the geophysical techniques, the active and passive surface wave, refraction and resistivity methods are mainly highlighted. Together with the geophysical techniques, several related issues, such as performance-based design, standardization or regularization, internet access and databases are also discussed. The presentation discusses the application of geophysical methods to engineering investigations from non-uniqueness point of view and introduces the concepts of integrated and quantitative. Most geophysical analyses are essentially non-unique and it is very difficult to obtain unique and reliable engineering solutions from only one geophysical method (Fig. 1). The only practical way to improve the reliability of investigation is the joint use of several geophysical and geotechnical investigation methods, an integrated approach to geophysics. The result of a geophysical method is generally vague, here is a high-velocity layer, it may be bed rock, this low resistivity section may contain clayey soils. Such vague, qualitative and subjective interpretation is not worthwhile on general engineering design works

  2. Surface geophysical methods for characterising frozen ground in transitional permafrost landscapes

    USGS Publications Warehouse

    Briggs, Martin; Campbell, Seth; Nolan, Jay; Walvoord, Michelle Ann; Ntarlagiannis, Dimitrios; Day-Lewis, Frederick D.; Lane, John

    2017-01-01

    The distribution of shallow frozen ground is paramount to research in cold regions, and is subject to temporal and spatial changes influenced by climate, landscape disturbance and ecosystem succession. Remote sensing from airborne and satellite platforms is increasing our understanding of landscape-scale permafrost distribution, but typically lacks the resolution to characterise finer-scale processes and phenomena, which are better captured by integrated surface geophysical methods. Here, we demonstrate the use of electrical resistivity imaging (ERI), electromagnetic induction (EMI), ground penetrating radar (GPR) and infrared imaging over multiple summer field seasons around the highly dynamic Twelvemile Lake, Yukon Flats, central Alaska, USA. Twelvemile Lake has generally receded in the past 30 yr, allowing permafrost aggradation in the receded margins, resulting in a mosaic of transient frozen ground adjacent to thick, older permafrost outside the original lakebed. ERI and EMI best evaluated the thickness of shallow, thin permafrost aggradation, which was not clear from frost probing or GPR surveys. GPR most precisely estimated the depth of the active layer, which forward electrical resistivity modelling indicated to be a difficult target for electrical methods, but could be more tractable in time-lapse mode. Infrared imaging of freshly dug soil pit walls captured active-layer thermal gradients at unprecedented resolution, which may be useful in calibrating emerging numerical models. GPR and EMI were able to cover landscape scales (several kilometres) efficiently, and new analysis software showcased here yields calibrated EMI data that reveal the complicated distribution of shallow permafrost in a transitional landscape.

  3. Glaciotectonic structures mapped by GPR, geoelectrical, high-resolution seismic and airborne transient electromagnetic methods

    NASA Astrophysics Data System (ADS)

    Høyer, Anne-Sophie; Møller, Ingelise; Jørgensen, Flemming

    2013-04-01

    Glaciotectonic structures have traditionally been recognized through observations in the landscape or exposures like cliffs. However, mapping of these structures can highly benefit from geophysical data, which can give information on buried glaciotectonic complexes. In the current study, we focus on the appearance of glaciotectonic structures in data from four commonly used geophysical methods: Ground penetrating radar (GPR), geoelectrical, high-resolution seismic and airborne transient electromagnetic (SkyTEM). The data are collected within a study area that covers 100 km2 and is located in the western part of Denmark. The study area is characterized by a highly heterogeneous geological setting, which has been influenced by multiple glacial deformation phases resulting in a buried glaciotectonic complex. The glaciotectonic structures appear as folds and faults and are recognizable at all scales. As a consequence of the different resolution capabilities of the methods, different degrees of detail are observed: Large-scale structures are recognized based on the seismic and airborne transient electromagnetic data, whereas small-scale structures are interpreted based on the GPR and geoelectrical data. At the same time, the nature of the methods results in different types of information from the data: The GPR and the seismic data generally provide detailed structural information, whereas the electric and electromagnetic data provide a more 'blurred' resistivity image of the subsurface. In order to recognize geological structures on the electric and electromagnetic data, the structures therefore need to influence sediments with contrasting resistivities to the surroundings. The structures are recognizable on all the different data sets, but the understanding and thus, the interpretation, of the geological environment strongly benefits from the combined observations from the different types of data.

  4. Adaptive mesh refinement and adjoint methods in geophysics simulations

    NASA Astrophysics Data System (ADS)

    Burstedde, Carsten

    2013-04-01

    It is an ongoing challenge to increase the resolution that can be achieved by numerical geophysics simulations. This applies to considering sub-kilometer mesh spacings in global-scale mantle convection simulations as well as to using frequencies up to 1 Hz in seismic wave propagation simulations. One central issue is the numerical cost, since for three-dimensional space discretizations, possibly combined with time stepping schemes, a doubling of resolution can lead to an increase in storage requirements and run time by factors between 8 and 16. A related challenge lies in the fact that an increase in resolution also increases the dimensionality of the model space that is needed to fully parametrize the physical properties of the simulated object (a.k.a. earth). Systems that exhibit a multiscale structure in space are candidates for employing adaptive mesh refinement, which varies the resolution locally. An example that we found well suited is the mantle, where plate boundaries and fault zones require a resolution on the km scale, while deeper area can be treated with 50 or 100 km mesh spacings. This approach effectively reduces the number of computational variables by several orders of magnitude. While in this case it is possible to derive the local adaptation pattern from known physical parameters, it is often unclear what are the most suitable criteria for adaptation. We will present the goal-oriented error estimation procedure, where such criteria are derived from an objective functional that represents the observables to be computed most accurately. Even though this approach is well studied, it is rarely used in the geophysics community. A related strategy to make finer resolution manageable is to design methods that automate the inference of model parameters. Tweaking more than a handful of numbers and judging the quality of the simulation by adhoc comparisons to known facts and observations is a tedious task and fundamentally limited by the turnaround times

  5. MAGNETOMETRY, SELF-POTENTIAL, AND SEISMIC - ADDITIONAL GEOPHYSICAL METHODS HAVING POTENTIALLY SIGNIFICANT FUTURE UTILIZATION IN AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods can provide important information in agricultural settings, and the use of these techniques are becoming more and more widespread. Magnetrometry, self-potential, and seismic are three geophysical methods, all of which have the potential for substantial future use in agriculture, ...

  6. Method of reducing impulsive noise in electromagnetic geophysical data

    SciTech Connect

    Spies, B.R.

    1990-07-31

    This patent describes a method of reducing impulsive noise in electromagnetic geophysical data. It comprises: providing receiving antenna means for receiving an electromagnetic signal. The receiving antenna means receiving impulsive noise; providing noise sensor means for receiving the impulsive noise and placing the noise sensor means so as to receive the impulsive noise that is received by the receiving antenna means and so as to minimize the reception of the electromagnetic signal; simultaneously receiving the electromagnetic signal with the receiving antenna means so as to create a signal record and receiving the impulsive noise with the noise sensor means so as to create a noise record; examining the noise record for occurrences of the impulsive noise by comparing the noise record with a threshold noise value and identifying those instances of time in which the noise record exceeds the threshold; removing those portions of the signal record which are simultaneous with the identified instances in which the noise records exceeds the threshold, wherein the signal record has reduced impulsive noise.

  7. Geophysical Inversion With Multi-Objective Global Optimization Methods

    NASA Astrophysics Data System (ADS)

    Lelièvre, Peter; Bijani, Rodrigo; Farquharson, Colin

    2016-04-01

    We are investigating the use of Pareto multi-objective global optimization (PMOGO) methods to solve numerically complicated geophysical inverse problems. PMOGO methods can be applied to highly nonlinear inverse problems, to those where derivatives are discontinuous or simply not obtainable, and to those were multiple minima exist in the problem space. PMOGO methods generate a suite of solutions that minimize multiple objectives (e.g. data misfits and regularization terms) in a Pareto-optimal sense. This allows a more complete assessment of the possibilities and provides opportunities to calculate statistics regarding the likelihood of particular model features. We are applying PMOGO methods to four classes of inverse problems. The first are discrete-body problems where the inversion determines values of several parameters that define the location, orientation, size and physical properties of an anomalous body represented by a simple shape, for example a sphere, ellipsoid, cylinder or cuboid. A PMOGO approach can determine not only the optimal shape parameters for the anomalous body but also the optimal shape itself. Furthermore, when one expects several anomalous bodies in the subsurface, a PMOGO inversion approach can determine an optimal number of parameterized bodies. The second class of inverse problems are standard mesh-based problems where the physical property values in each cell are treated as continuous variables. The third class of problems are lithological inversions, which are also mesh-based but cells can only take discrete physical property values corresponding to known or assumed rock units. In the fourth class, surface geometry inversions, we consider a fundamentally different type of problem in which a model comprises wireframe surfaces representing contacts between rock units. The physical properties of each rock unit remain fixed while the inversion controls the position of the contact surfaces via control nodes. Surface geometry inversion can be

  8. EVALUATION OF GEOPHYSICAL METHODS FOR THE DETECTION OF SUBSURFACE TETRACHLOROETHYLENE IN CONTROLLED SPILL EXPERIMENTS

    EPA Science Inventory

    The purpose of the work was to determine the capability of various geophysical methods to detect PCE in the subsurface. Measurements were made with ten different geophysical techniques before, during, and after the PCE injection. This approach provided a clear identification of a...

  9. New geophysical electromagnetic method of archeological object research in Egypt

    NASA Astrophysics Data System (ADS)

    Hachay, O. A.; Khachay, O. Yu.; Attia, Magdi.

    2009-04-01

    The demand to the enhanced geophysical technique and device, in addition to the precise interpretation of the geophysical data, is the resolution of the geophysical complex research, especially by the absence of priory information about the researched place. Therefore, an approach to use the planshet method of electromagnetic induction in the frequency geometry was developed by Hachay. et al., 1997a, 1997b, 1999, 2000, 2002, and 2005. The method was adapted to map and monitor the high complicated geological mediums, to determine the structural factors and criteria of the rock massif in the mine subsurface. The field observation and the way of interpretation make the new technology differ from other known earlier methods of field raying or tomography (Hachay et al., 1997c, 1999, and 2000).The 3D geoelectrical medium research is based on the concept of three staged interpreting of the alternating electromagnetic field in a frame of the block-layered isotropic medium with inclusion (Hachay 1997a, and 2002); in the first stage, the geoelectrical parameters of the horizontal block-layered medium, which includes the heterogeneities, are defined. In the second stage a geometrical model of the different local heterogeneities or groups inside the block-layered medium is constructed based on the local geoelectrical heterogeneities produced from the first stage after filtering the anomalous fields plunged in the medium. While in the third stage, the surfaces of the searched heterogeneities could be calculated in account of the physical parameters of the anomalous objects.For practical realization of that conception the system of observation for alternating electromagnetic field with use of vertical magnetic dipole was elaborated. Such local source of excitation and regular net of observations allows realizing overlapping by different angles of observation directions. As incoming data for interpretation, three components of modules of three components of magnetic field are

  10. Geothermal Geophysical Research in Electrical Methods at UURI

    SciTech Connect

    Wannamaker, Philip E.; Wright, Phillip M.

    1992-03-24

    The principal objective of electrical geophysical research at UURI has been to provide reliable exploration and reservoir assessment tools for the shallowest to the deepest levels of interest in geothermal fields. Three diverse methods are being considered currently: magnetotellurics (MT, and CSAMT), self-potential, and borehole resistivity. Primary shortcomings in the methods addressed have included a lack of proper interpretation tools to treat the effects of the inhomogeneous structures often encountered in geothermal systems, a lack of field data of sufficient accuracy and quantity to provide well-focused models of subsurface resistivity structure, and a poor understanding of the relation of resistivity to geothermal systems and physicochemical conditions in the earth generally. In MT, for example, interpretation research has focused successfully on the applicability of 2-D models in 3-D areas which show a preferred structural grain. Leading computer algorithms for 2-D and 3-D simulation have resulted and are combined with modern methods of regularized inversion. However, 3-D data coverage and interpretation is seen as a high priority. High data quality in our own research surveys has been assured by implementing a fully remote reference with digital FM telemetry and real-time processing with data coherence sorting. A detailed MT profile across Long Valley has mapped a caldera-wide altered tuff unit serving as the primary hydrothermal aquifer, and identified a low-resistivity body in the middle crust under the west moat which corresponds closely with teleseismic delay and low density models. In the CSAMT method, our extensive tensor survey over the Sulphur Springs geothermal system provides valuable structural information on this important thermal regime and allows a fundamental analysis of the CSAMT method in heterogeneous areas. The self-potential (SP) method is promoted as an early-stage, cost-effective, exploration technique for covered hydrothermal

  11. Methods and applications of radio frequency geophysics in glaciology

    NASA Astrophysics Data System (ADS)

    Holschuh, Nicholas

    Simple radar systems of the past were used primarily for radar depth sounding, the process of using reflection travel times and electromagnetic velocities to determine the ice thickness. Modern radioglaciology uses both the travel times and reflection amplitudes to make inferences about the englacial and subglacial environments; however, non-uniqueness in geophysical data, combined with the large number of physical parameters that control reflection amplitude, have led to significant uncertainties in this type of analysis. In this set of studies, I improve on data collection, processing, and assimilation methods, with a focus on radar reflection amplitudes and internal layers. The first two studies are devoted to radar survey methods, in which I examine the impact of reflector geometry on amplitude (2), and investigate an independent measure of radar attenuation using variable-offset data, in an effort to eliminate the effects of ice chemistry and temperature on reflection amplitudes (3). These studies emphasize the fact that radar data are a product of both the physical system and the imaging process, and caution glaciologists from over-interpreting processing artifacts common in radar data collected in areas of complex glacial flow. In the following two chapters, I go on to provide glaciological applications of processed radar data, interpreting the record of complex flow left behind in englacial reflector slopes (4), and applying improved boundary conditions to better predict the maximum extent of West Antarctic collapse (5). These studies use geometric information from the bed reflector and englacial reflectors to describe the flow regime present in Antarctica today. Chapter 4 examines how boundary conditions that are difficult to observe directly (the geothermal heat flux, as well as the frictional and deformation characteristics of the ice-sheet substrate) manifest through internal layer deformation. Chapter 5 focuses on Marie Byrd Land (MBL), where

  12. Mapping and discriminating the Pan-African granitoids in the Hoggar (southern Algeria) using Landsat 7 ETM+ data and airborne geophysics

    NASA Astrophysics Data System (ADS)

    Zerrouk, Siham; Bendaoud, Abderrahmane; Hamoudi, Mohamed; Liégeois, Jean Paul; Boubekri, Hichem; El Khaznadji, Riad Ben

    2017-03-01

    This study presents a multidisciplinary approach to discriminate and map different types and generations of Pan-African granitoids in the Hoggar, southern Algeria, using remote sensing and airborne geophysics in close correlation with previous works and established geological maps. RGB (Red, Green, Blue) combinations of band ratios; principal component analysis (PCA) and image classification for Landsat 7 ETM+ (Enhanced Thematic Mapper Plus), allow spatial discrimination and mapping of granitoid rocks of the studied area (200*350 km). This area extend over four contrasted Pan-African terranes (In Tedeini, Iskel, Tefedest and Laouni terranes, the two latter belong to the LATEA (Laouni-Azrou-n-Fad-Tefedest-Egéré-Aleksod-Assodé-Issalane) metacraton. The airborne magnetic intensity provides a wide range of responses from high values (youngest granitoids) to low values (volcano-sedimentary and gneissic country-rocks). Radiometric data, displaying radioelements concentration, discriminate efficiently the late alkaline granitoids (high values), the calk-alkaline granitoids (intermediate values) and the Tonalite-Trondhjemite-Granodiorite series (low values). This study led to the establishment of a more accurate geological map where the geochemical characteristics of the Pan-African granitoids are determined, including plutons not yet studied, especially in the poorly known In Tedeini terrane, and brings new constraints for the geodynamic development of the Tuareg Shield, which includes the Hoggar.

  13. Formal methods and digital systems validation for airborne systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1993-01-01

    This report has been prepared to supplement a forthcoming chapter on formal methods in the FAA Digital Systems Validation Handbook. Its purpose is as follows: to outline the technical basis for formal methods in computer science; to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used on board aircraft; and to suggest factors for consideration when formal methods are offered in support of certification. These latter factors assume the context for software development and assurance described in RTCA document DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,' Dec. 1992.

  14. Mapping Ground Water in Three Dimensions - An Analysis of Airborne Geophysical Surveys of the Upper San Pedro River Basin, Cochise County, Southeastern Arizona

    USGS Publications Warehouse

    Wynn, Jeff

    2006-01-01

    This report summarizes the results of two airborne geophysical surveys conducted in the upper San Pedro Valley of southeastern Arizona in 1997 and 1999. The combined surveys cover about 1,000 square kilometers and extend from the Huachuca Mountains on the west to the Mule Mountains and Tombstone Hills on the east and from north of the Babocomari River to near the Mexican border on the south. The surveys included the acquisition of high-resolution magnetic data, which were used to map depth to the crystalline basement rocks underlying the sediments filling the basin. The magnetic inversion results show a complex basement morphology, with sediment thickness in the center of the valley ranging from ~237 meters beneath the city of Sierra Vista to ~1,500 meters beneath Huachuca City and the Palominas area near the Mexican border. The surveys also included acquisition of 60-channel time-domain electromagnetic (EM) data. Extensive quality analyses of these data, including inversion to conductivity vs. depth (conductivity-depth-transform or CDT) profiles and comparisons with electrical well logs, show that the electrical conductor mapped represents the subsurface water-bearing sediments throughout most of the basin. In a few places (notably the mouth of Huachuca Canyon), the reported water table lies above where the electrical conductor places it. These exceptions appear to be due to a combination of outdated water-table information, significant horizontal displacement between the wells and the CDT profiles, and a subtle calibration issue with the CDT algorithm apparent only in areas of highly resistive (very dry) overburden. These occasional disparities appear in less than 5 percent of the surveyed area. Observations show, however, that wells drilled in the thick unsaturated zone along the Huachuca Mountain front eventually intersect water, at which point the water rapidly rises high into the unsaturated zone within the wellbore. This rising of water in a wellbore implies

  15. Use of airborne electromagnetic methods for resource mapping

    NASA Astrophysics Data System (ADS)

    Palacky, G. J.

    1993-11-01

    Airborne electromagnetic (AEM) methods complement spaceborne remote sensing techniques. AEM surveys carried out from low flying aircraft are capable of detecting geological structures not visible on the surface. The flight height of AEM systems above the ground ranges from 30 to 120 m. Most systems generate primary EM fields by using a loop transmitter; conducting coils are used as antenna to measure the secondary magnetic field caused by conductive inhomogeneities in the ground. The frequency used in AEM surveys (100 Hz to 50 kHz) allows ground penetration in excess of 100 m. At present, two types of AEM systems are widely used: helicopter, frequency-domain, and fixed-wing, towed-bird, time-domain. The most common survey products are apparent conductivity maps. AEM methods are extensively used in prospecting for base and precious metal deposits, kimberlites, uranium, and also in geological mapping, groundwater exploration and environmental investigations.

  16. Investigation of a playa lake bed using geophysical electrical methods

    NASA Astrophysics Data System (ADS)

    Herrmenn, M.; Gurrola, H.; William, R.; Montalvo, R.; Horton, S.; Homberg, J.; Allen, T.; Bribiesca, E.; Lindsey, C.; Anderson, H.; Seshadri, S.; Manns, S.; Hassan, A.; Loren, C.

    2005-12-01

    The 2005 undergraduate applied geophysical class of Texas Tech University conducted a geophysical survey of a playa lake approximately 10 miles northwest of Lubbock Texas. The playa lake is primarily used as grazing land for two llamas and a hand full of sheep, and has been recently used as a dump for broken down sheds and barrels. Our goal was to model the subsurface of the transition from the playa to plains geology and investigate the possible contamination, of the soil and the data, by the metal dumped at the surface. We conducted our survey with and EM31 and homemade D.C. resistivity and SP equipment that allowed students to grasp the theories more clearly. SP readings were collected using clay pots constructed from terracotta pots and copper tubing purchased at the local hardware store and voltage measurements collected with handle held multi-meters. D.C. resistivity data were collected in a dipole-dipole array using 20 nine volt batteries connected in series with a large enough variable resistor and amp meter to regulate steady current flow. A multi meter was used to collect voltage readings. Wenner array data were collected using a home-made multi-filament cable connected switch box to allow a central user to regulate current and take voltage reading. A map of conductivity produced from a 10 m of EM31 reading show that conductivity anomalies mirror topography. The SP profiles show high values in the playa lake that drop off as we move from the clay rich lake bed to normal grassland. Analysis of both the Dipole-Dipole and Wenner array data support a model with 3 flat layers increasing in resistivity with depth. It appears that these remain flat passing beneath the playa and the playa is eroded into these layers.

  17. Multi-Faceted Geophysical Analysis of a Mountain Watershed in the Snowy Range, WY: from Airborne Electromagnetics to NMR

    NASA Astrophysics Data System (ADS)

    Armstrong, R. S.; Holbrook, W. S.; Flinchum, B. A.; Provart, M.; Carr, B. J.; Auken, E.; Pedersen, J. B.

    2014-12-01

    Surface/groundwater interactions are an important, but poorly understood, facet of mountain hydrology. We utilize ground electrical resistivity data as a key tool for mapping groundwater pathways and aquifers. However, surface resistivity profiling is limited in both spatial extent and depth, especially in mountainous headwater environments because of inaccessibility and terrain. Because this important groundwater recharge environment is poorly understood, WyCEHG has focused efforts to increase knowledge about the dynamics and location of groundwater recharge. Currently, traditional hydrologic measurements estimate that only 10% of annual snowmelt enters the groundwater system while the rest is immediately available to surface flow. The Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG) collected a 40 sq. km survey of helicopter transient electromagnetic (HTEM) and aeromagnetic data during the fall of 2013 as the first step in a "top down" geophysical characterization of a mountainous headwater catchment in the Snowy Range, Wyoming. Furthermore, mountain springs in the Snowy Range suggests that the "groundwatershed" acts as both a sink and source to surface watersheds. HTEM data show horizontal electrical conductors at depth, which are currently interpreted as fluid-filled subsurface fractures. Because these fractures eventually connect to the surface, they could be geophysical evidence of connectivity between the watershed and "groundwatershed." However, current HTEM inversion techniques assume a layered homogenous subsurface model, which directly contradicts two characteristics of the Snowy Range: the subvertical bedding of the Cheyenne Belt and heterogeneous distribution of surface water. Ground electrical resistivity surveys and surface nuclear magnetic resonance (NMR) measurements collected during the summer of 2014 target these anomalies to determine their validity and further understand the complicated dynamic of surface and groundwater flow.

  18. Detecting Light Hydrocarbon Microseepages and related Intra-sedimentary Structures at the São Francisco Basin, Brazil, using Airborne Geophysical Data

    NASA Astrophysics Data System (ADS)

    Curto, J. B.; Pires, A. C.; Silva, A.; Crosta, A. P.

    2011-12-01

    The use of indirect techniques for the detection of light hydrocarbons occurrences on the surface, named as microseepages, has been used to augment hydrocarbon exploration. Surveys developed for this type of application are normally targeted at mapping the effects that microseepages cause on the environment. In Brazil, most available airborne geophysical surveys were not appropriately designed for this type of application and, thus far they have been mostly used to define the main basin structural features. Existing microseepages are known in Remanso do Fogo area (Minas Gerais State, Brazil), located in São Francisco Basin, where the Quaternary sedimentary cover made the identification of new occurrences and associated controlling structures quite difficult. This study investigates the spatial distribution of hydrocarbon related structures in shallower to intra-sedimentary depths in the Remanso do Fogo area, using airborne magnetic and gamma-ray spectrometry data. These data were managed by the ANP (Brazilian Petroleum National Agency) and conducted by Lasa Engineering & Surveys in 2006. In the study area, data were acquired along north-south flight lines spaced 500 m apart and along orthogonal tie lines flown 4 Km apart at a terrain clearance of 100 m. The geophysical data were processed using techniques developed to suppress the influence of regional geological signatures. For the magnetic data, this study focuses on the enhancement of intra-sedimentary structures and possible near surface accumulations of diagenetic magnetic minerals, provided by hydrocarbon related chemical reactions. The amplitude of the analytic signal, calculated with second order derivatives, combined with the total horizontal gradient of the subtraction between the 1200 and 400 meter upward continuations, illuminated the NW and EW magnetic lineaments, which are partially related to the microseepages and the drainage of the area. The distinction of near-surface and deeper signatures also

  19. Agricultural Geophysics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The four geophysical methods predominantly used for agricultural purposes are resistivity, electromagnetic induction, ground penetrating radar (GPR), and time domain reflectometry (TDR). Resistivity and electromagnetic induction methods are typically employed to map lateral variations of apparent so...

  20. Evaluation of airborne geophysical surveys for large-scale mapping of contaminated mine pools: draft final report

    SciTech Connect

    Hammack, R. W.

    2006-12-28

    subtle mine pool anomalies. However, post-survey modeling suggested that thicker, more conductive mine pools might be detected at a more suitable location. The current study sought to identify the best time domain electromagnetic sensor for detecting mine pools and to test it in an area where the mine pools are thicker and more conductive that those in southwestern Virginia. After a careful comparison of all airborne time domain electromagnetic sensors (including both helicopter and fixed-wing systems), the SkyTEM system from Denmark was determined to be the best technology for this application. Whereas most airborne time domain electromagnetic systems were developed to find large, deep, highly conductive mineral deposits, the SkyTEM system is designed for groundwater exploration studies, an application similar to mine pool detection.

  1. Requirements for airborne vector gravimetry

    NASA Technical Reports Server (NTRS)

    Schwarz, K. P.; Colombo, O.; Hein, G.; Knickmeyer, E. T.

    1992-01-01

    The objective of airborne vector gravimetry is the determination of the full gravity disturbance vector along the aircraft trajectory. The paper briefly outlines the concept of this method using a combination of inertial and GPS-satellite data. The accuracy requirements for users in geodesy and solid earth geophysics, oceanography and exploration geophysics are then specified. Using these requirements, accuracy specifications for the GPS subsystem and the INS subsystem are developed. The integration of the subsystems and the problems connected with it are briefly discussed and operational methods are indicated that might reduce some of the stringent accuracy requirements.

  2. Geophysical technique for mineral exploration and discrimination based on electromagnetic methods and associated systems

    DOEpatents

    Zhdanov; Michael S.

    2008-01-29

    Mineral exploration needs a reliable method to distinguish between uneconomic mineral deposits and economic mineralization. A method and system includes a geophysical technique for subsurface material characterization, mineral exploration and mineral discrimination. The technique introduced in this invention detects induced polarization effects in electromagnetic data and uses remote geophysical observations to determine the parameters of an effective conductivity relaxation model using a composite analytical multi-phase model of the rock formations. The conductivity relaxation model and analytical model can be used to determine parameters related by analytical expressions to the physical characteristics of the microstructure of the rocks and minerals. These parameters are ultimately used for the discrimination of different components in underground formations, and in this way provide an ability to distinguish between uneconomic mineral deposits and zones of economic mineralization using geophysical remote sensing technology.

  3. A new noise reduction method for airborne gravity gradient data

    NASA Astrophysics Data System (ADS)

    Jirigalatu; Ebbing, Jörg; Sebera, Josef

    2016-09-01

    Airborne gravity gradient (AGG) measurements offer an increased resolution and accuracy compared to terrestrial measurements. But interpretation and processing of AGG data are often challenging as levelling errors and survey noise affect the data, and these effects are not easily recognised in the gradient components. We adopted the classic method of upward continuation in the noise reduction using the noise level estimates by the AGG system. By iteratively projecting the survey data to a lower level and upward continuing the data back to the survey height, parts of the high-frequency signal are suppressed. The filter, which is defined by this approach, is directly dependent on the noise level of the AGG data, the maximum number of iterations and the iterative step. We demonstrate the method by applying it to both synthetic data and real AGG data over Karasjok, Norway, and compare the results to the directional filtering method. The results show that the iterative filter can effectively reduce high-frequency noise in the data.

  4. From IGY to IPY, the U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program from 1957 to 1964 from the View of a Young Graduate Student

    NASA Astrophysics Data System (ADS)

    Behrendt, J. C.

    2006-12-01

    1958 and continuing to 1964 the oversnow traverses were complimented by an airborne geophysical program comprising widely spaced landings for seismic reflection ice sounding and 75,000 km of widely spaced aeromagnetic and snow surface elevation profiles. The airborne profiles were concentrated over the West Antarctic Ice Sheet (WAIS) and along the length of the Transantarctic Mountains, and approximately defined the vast extent of a late Cenozoic volcanic province beneath the WAIS associated with the unknown West Antarctic rift system. There were numerous hazards encountered using these U.S. Navy planes of opportunity including denting a wing on a hidden mountain and a crash on one occasion killing the geophysicist (Edward Thiel) and four others. There was an aircraft death rate of 3.8 deaths per year in the U.S. program from 1955-66. The oversnow and airborne traverses of the IGY-IGC period employed the inductive method of scientific research with only the general objectives of defining the Antarctic Ice Sheet as to surface elevation, thickness, snow accumulation and temperature. In contrast, Antarctic research today employs deductive logic with narrowly defined objectives and testing of hypotheses. This change has been necessary because of expense, and competition of proposals by many scientists. Nonetheless something has been lost by this approach, and there is still the need for "exploration" types of research is the still unknown vast continent of Antarctica.

  5. From Mars to Greenland: Charting gravity with space and airborne instruments - Fields, tides, methods, results

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L. (Editor)

    1992-01-01

    This symposium on space and airborne techniques for measuring gravity fields, and related theory, contains papers on gravity modeling of Mars and Venus at NASA/GSFC, an integrated laser Doppler method for measuring planetary gravity fields, observed temporal variations in the earth's gravity field from 16-year Starlette orbit analysis, high-resolution gravity models combining terrestrial and satellite data, the effect of water vapor corrections for satellite altimeter measurements of the geoid, and laboratory demonstrations of superconducting gravity and inertial sensors for space and airborne gravity measurements. Other papers are on airborne gravity measurements over the Kelvin Seamount; the accuracy of GPS-derived acceleration from moving platform tests; airborne gravimetry, altimetry, and GPS navigation errors; controlling common mode stabilization errors in airborne gravity gradiometry, GPS/INS gravity measurements in space and on a balloon, and Walsh-Fourier series expansion of the earth's gravitational potential.

  6. Understanding the thermal and tectonic evolution of Marie Byrd Land from a reanalysis of airborne geophysical data in the West Antarctic Rift System

    NASA Astrophysics Data System (ADS)

    Quartini, E.; Powell, E. M.; Richter, T.; Damiani, T.; Burris, S. G.; Young, D. A.; Blankenship, D. D.

    2013-12-01

    The West Antarctic Rift System (WARS) is a region characterized by a significant topographic range, a complex tectonic history, and active subglacial volcanism. Those elements exert a large influence on the stability of the West Antarctic Ice Sheet, which flows within the cradle-shaped rift system and is currently grounded well below sea level. This potentially unstable configuration is the motivation for gaining a better understanding of the ice sheet boundary conditions dictated by rift evolution and how they impact the ice flow. In this study we focus on characterizing the distribution of and transition between sedimentary basins and inferred geothermal heat flux from the flanks to the floor of the rift system. We do so through analysis of gravity data both for sources within the deep lithosphere and near surface targets in the crust. A compilation of gravity datasets over West and Central Antarctica and the analysis thereof is presented. In particular we use gravity data collected during several airborne geophysical surveys: CASERTZ (1994-1997), SOAR/WMB (1997-1998), AGASEA (2004-2005), ICEBRIDGE (2008-2011), and GIMBLE (2012-2013). New processing and data reduction methodologies are applied to the older gravity surveys to improve the high frequency signal content and to make these surveys compatible with modern works (i.e. AGASEA, ICEBRIDGE, GIMBLE). The high frequency signal provides better resolution of small-scale features within survey blocks but long-wavelength integrity is retained by registering the airborne free-air disturbance within those blocks to the gravity disturbance derived from the GOCE global satellite gravity field. This allows for consistent long wavelength interpretation across the merged surveys and provides improved gravity analysis of the deep lithosphere while retaining the capacity to study smaller scale features. A crustal model for the area is produced using the Bouguer anomaly and spectral analyses of the Bouguer anomaly and free

  7. Signal analysis and radioholographic methods for airborne radio occultations

    NASA Astrophysics Data System (ADS)

    Wang, Kuo-Nung

    Global Positioning System (GPS) radio occultation (RO) is an atmospheric sounding technique utilizing the change in propagation direction and delay of the GPS signal to measure refractivity, which provides information on temperature and humidity. The GPS-RO technique is now operational on several Low Earth Orbiting (LEO) satellite missions. Nevertheless, when observing localized transient events, such as tropical storms, current LEO satellite systems cannot provide sufficiently high temporal and spatial resolution soundings. An airborne RO (ARO) system has therefore been developed for localized GPS-RO campaigns. The open-loop (OL) tracking in post-processing is used to cross-correlates the received Global Navigation Satellite System (GNSS) signal with an internally generated local carrier signal predicted from a Doppler model and extract the atmospheric refractivity information. OL tracking also allows robust processing of rising GPS signals using backward tracking, which will double the observed occultation event numbers. RO signals in the lower troposphere are adversely affected by rapid phase accelerations and severe signal power fading, however. The negative bias caused by low signal-to-noise ratio (SNR) and multipath ray propagation limits the depth of tracking in the atmosphere. Therefore, we developed a model relating the SNR to the variance in the residual phase of the observed signal produced from OL tracking, and its applicability to airborne data is demonstrated. We then apply this model to set a threshold on refractivity retrieval, based upon the cumulative unwrapping error bias, to determine the altitude limit for reliable signal tracking. To enhance the SNR and decrease the unwrapping error rate, the CIRA-Q climatological model and signal residual phase pre-filtering are utilized to process the ARO residual phase. This more accurately modeled phase and less noisy received signal are shown to greatly reduce the bias caused by unwrapping error at lower

  8. Multigrid methods and the surface consistent equations of Geophysics

    NASA Astrophysics Data System (ADS)

    Millar, John

    The surface consistent equations are a large linear system that is frequently used in signal enhancement for land seismic surveys. Different signatures may be consistent with a particular dynamite (or other) source. Each receiver and the conditions around the receiver will have different impact on the signal. Seismic deconvolution operators, amplitude corrections and static shifts of traces are calculated using the surface consistent equations, both in commercial and scientific seismic processing software. The system of equations is singular, making direct methods such as Gaussian elimination impossible to implement. Iterative methods such as Gauss-Seidel and conjugate gradient are frequently used. A limitation in the nature of the methods leave the long wavelengths of the solution poorly resolved. To reduce the limitations of traditional iterative methods, we employ a multigrid method. Multigrid methods re-sample the entire system of equations on a more coarse grid. An iterative method is employed on the coarse grid. The long wavelengths of the solutions that traditional iterative methods were unable to resolve are calculated on the reduced system of equations. The coarse estimate can be interpolated back up to the original sample rate, and refined using a standard iterative procedure. Multigrid methods provide more accurate solutions to the surface consistent equations, with the largest improvement concentrated in the long wavelengths. Synthetic models and tests on field data show that multigrid solutions to the system of equations can significantly increase the resolution of the seismic data, when used to correct both static time shifts and in calculating deconvolution operators. The first chapter of this thesis is a description of the physical model we are addressing. It reviews some of the literature concerning the surface consistent equations, and provides background on the nature of the problem. Chapter 2 contains a review of iterative and multigrid methods

  9. Electromagnetic Induction Methods in Mining Geophysics from 2008 to 2012

    NASA Astrophysics Data System (ADS)

    Smith, Richard

    2014-01-01

    In the period from 2008 to 2012, the topic of electromagnetic (EM) induction methods applied to mineral exploration has been the subject of more than 50 papers in journals and more than 300 extended abstracts presented at conferences (about 100 of which contain developments worthy of mentioning). Most of the work at the universities has been on modelling, inversion and data processing, and most of this material is published in the refereed literature. However, academia has also undertaken work on system geometry changes, system calibration and sensor design. There have been papers describing new systems developed for mineral exploration and case histories describing the use of EM methods to directly discover mineral deposits or to map the geology. Most of this work is by the service companies and mining companies and reported in the unrefereed literature. Since 2008, the pace of development of helicopter time-domain systems has slowed and more effort has been directed to developing natural source magnetic systems and to modelling and inverting this data. A number of studies comparing the results from natural source methods with the results from artificial source methods conclude that the natural source methods can see large-scale geological structures usually when there is a weak conductivity contrast with the surrounding material, but the natural source methods are unable to see small features that have a very large conductivity contrast with the country rock. Hence, they are not a good detector of mineral deposits unless one is looking for a large porphyry system.

  10. Integrated geophysical methods for studying the karst system of Gruta de las Maravillas (Aracena, Southwest Spain)

    NASA Astrophysics Data System (ADS)

    Martínez-Moreno, F. J.; Galindo-Zaldívar, J.; Pedrera, A.; Teixido, T.; Ruano, P.; Peña, J. A.; González-Castillo, L.; Ruiz-Constán, A.; López-Chicano, M.; Martín-Rosales, W.

    2014-08-01

    In this study we contrast the results of different geophysical methods in order to describe the karst system surrounding of the Gruta de las Maravillas cave (Aracena, Spain). A comprehensive study of the geophysical responses of the known cavity was carried out, after which several sections were studied to detect the karst architecture and cave continuity. To ensure precision, the inner 3D-topography of the cave was determined by classical geodetic techniques and a digital terrain model was performed with differential GPS. The microgravity method was used to obtain the residual gravity map of the entire study zone, whose minima could be related to caves. Then, the negative gravity anomalies were analyzed to plan several lines for implementing further geophysical methods: magnetic profiles (MP), electrical resistivity tomography (ERT), induced polarization (IP), 2D seismic prospection (refraction tomography and reflection sections) and ground penetrating radar (GPR). The resulting models for each line explored were integrated with detailed geological maps to establish the unknown continuity of the caves. Finally, we discuss the suitability of each geophysical technique for cave detection in marble with sulfur host rock and propose the best procedures to constrain their geometries.

  11. Subsurface Cavity Detection by Using Integrated Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Aykaç, Sinem; Rezzan Ozerk, Zeynep; Işıkdeniz Şerifoǧlu, Betül; Bihter Demirci, Büşra; Timur, Emre; Çakir, Korhan

    2016-04-01

    Global warming experienced in recent years in Turkey has led to a severe drought around the Konya Plain in central Anatolia .As a result, excessive amount of ground water was drawn in the region for the sustainability of agricultural activities. So, five small-scale shallow depth sinkholes have occured at different times, at an average interval between 400-450 m. in the study area; Konya-Atlantı. Generally, sinkholes formation occurres among natural processes has turned into disasters caused by humans due to excessive use of groundwater. Consequently, investigations were carried out within a partnership research programme on cavity detection and ground penetration radar, microgravity and multi-frequency electromagnetic methods were jointly utilized. . Exact locations and dimensions of two possible hidden cavities were determined by using these multidisciplinary methods. Keywords: Cavity;Ground-penetrating radar;Konya;Microgravimetry;Multi-frequency electromagnetic method.

  12. Some splitting methods for equations of geophysical fluid dynamics

    NASA Astrophysics Data System (ADS)

    Ji, Zhongzhen; Wang, Bin

    1995-03-01

    In this paper, equations of atmospheric and oceanic dynamics are reduced to a kind of evolutionary equation in operator form, based on which a conclusion that the separability of motion stages is relative is made and an issue that the tractional splitting methods established on the physical separability of the fast stage and the slow stage neglect the interaction between the two stages to some extent is shown. Also, three splitting patterns are summed up from the splitting methods in common use so that a comparison between them is carried out. The comparison shows that only the improved splitting pattern (ISP) can be in second order and keep the interaction well. Finally, the applications of some splitting methods on numerical simulations of typhoon tracks made clear that ISP owns the best effect and can save more than 80% CPU time.

  13. Joint Geophysical Inversion With Multi-Objective Global Optimization Methods

    NASA Astrophysics Data System (ADS)

    Lelievre, P. G.; Bijani, R.; Farquharson, C. G.

    2015-12-01

    Pareto multi-objective global optimization (PMOGO) methods generate a suite of solutions that minimize multiple objectives (e.g. data misfits and regularization terms) in a Pareto-optimal sense. Providing a suite of models, as opposed to a single model that minimizes a weighted sum of objectives, allows a more complete assessment of the possibilities and avoids the often difficult choice of how to weight each objective. We are applying PMOGO methods to three classes of inverse problems. The first class are standard mesh-based problems where the physical property values in each cell are treated as continuous variables. The second class of problems are also mesh-based but cells can only take discrete physical property values corresponding to known or assumed rock units. In the third class we consider a fundamentally different type of inversion in which a model comprises wireframe surfaces representing contacts between rock units; the physical properties of each rock unit remain fixed while the inversion controls the position of the contact surfaces via control nodes. This third class of problem is essentially a geometry inversion, which can be used to recover the unknown geometry of a target body or to investigate the viability of a proposed Earth model. Joint inversion is greatly simplified for the latter two problem classes because no additional mathematical coupling measure is required in the objective function. PMOGO methods can solve numerically complicated problems that could not be solved with standard descent-based local minimization methods. This includes the latter two classes of problems mentioned above. There are significant increases in the computational requirements when PMOGO methods are used but these can be ameliorated using parallelization and problem dimension reduction strategies.

  14. Evaluation of geophysical methods for the detection of subsurfacetetracgloroethyene in controlled spill experiments

    SciTech Connect

    Mazzella, Aldo; Majer, Ernest L.

    2006-04-10

    A controlled Tetrachloroethylene (PCE) spill experiment was conducted in a multi-layer formation consisting of sand and clayey-sandlayers. The purpose of the work was to determine the detection limits and capability of various geophysical methods. Measurements were made with ten different geophysical techniques before, during, and after the PCE injection. This experiment provided a clear identification of any geophysical anomalies associated with the presence of the PCE. During the injection period all the techniques indicated anomalies associated with the PCE. In order to quantify the results and provide an indication of the PCE detection limits of the various geophysical methods, the tank was subsequently excavated and samples of the various layers were analyzed for residual PCE concentration with gas chromatography (GC). 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), and borehole video (BV).

  15. Modeling and Evaluation of Geophysical Methods for Monitoring and Tracking CO2 Migration

    SciTech Connect

    Daniels, Jeff

    2012-11-30

    Geological sequestration has been proposed as a viable option for mitigating the vast amount of CO{sub 2} being released into the atmosphere daily. Test sites for CO{sub 2} injection have been appearing across the world to ascertain the feasibility of capturing and sequestering carbon dioxide. A major concern with full scale implementation is monitoring and verifying the permanence of injected CO{sub 2}. Geophysical methods, an exploration industry standard, are non-invasive imaging techniques that can be implemented to address that concern. Geophysical methods, seismic and electromagnetic, play a crucial role in monitoring the subsurface pre- and post-injection. Seismic techniques have been the most popular but electromagnetic methods are gaining interest. The primary goal of this project was to develop a new geophysical tool, a software program called GphyzCO2, to investigate the implementation of geophysical monitoring for detecting injected CO{sub 2} at test sites. The GphyzCO2 software consists of interconnected programs that encompass well logging, seismic, and electromagnetic methods. The software enables users to design and execute 3D surface-to-surface (conventional surface seismic) and borehole-to-borehole (cross-hole seismic and electromagnetic methods) numerical modeling surveys. The generalized flow of the program begins with building a complex 3D subsurface geological model, assigning properties to the models that mimic a potential CO{sub 2} injection site, numerically forward model a geophysical survey, and analyze the results. A test site located in Warren County, Ohio was selected as the test site for the full implementation of GphyzCO2. Specific interest was placed on a potential reservoir target, the Mount Simon Sandstone, and cap rock, the Eau Claire Formation. Analysis of the test site included well log data, physical property measurements (porosity), core sample resistivity measurements, calculating electrical permittivity values, seismic data

  16. Simple method for measuring vibration amplitude of high power airborne ultrasonic transducer: using thermo-couple.

    PubMed

    Saffar, Saber; Abdullah, Amir

    2014-03-01

    Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach.

  17. Field Demonstrations of Five Geophysical Methods that Could Be Used to Characterize Deposits of Alluvial Aggregate

    USGS Publications Warehouse

    Ellefsen, K.J.; Burton, B.L.; Lucius, J.E.; Haines, S.S.; Fitterman, D.V.; Witty, J.A.; Carlson, D.; Milburn, B.; Langer, W.H.

    2007-01-01

    Personnel from the U.S. Geological Survey and Martin Marietta Aggregates, Inc., conducted field demonstrations of five different geophysical methods to show how these methods could be used to characterize deposits of alluvial aggregate. The methods were time-domain electromagnetic sounding, electrical resistivity profiling, S-wave reflection profiling, S-wave refraction profiling, and P-wave refraction profiling. All demonstrations were conducted at one site within a river valley in central Indiana, where the stratigraphy consisted of 1 to 2 meters of clay-rich soil, 20 to 35 meters of alluvial sand and gravel, 1 to 6 meters of clay, and multiple layers of limestone and dolomite bedrock. All geophysical methods, except time-domain electromagnetic sounding, provided information about the alluvial aggregate that was consistent with the known geology. Although time-domain electromagnetic sounding did not work well at this site, it has worked well at other sites with different geology. All of these geophysical methods complement traditional methods of geologic characterization such as drilling.

  18. Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

    SciTech Connect

    Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris; Williams, Kenneth H.

    2015-02-24

    This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR) and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements

  19. Results of investigation at the Ahuachapan Geothermal Field, El Salvador. Part 2, Electrical-methods geophysics: Final report

    SciTech Connect

    Fink, J.B.

    1990-04-01

    The Ahuachapan Geothermal Field (AGF) is a 95 megawatt geothemal-sourced power-plant operated by the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) of El Salvador. During the past decade, as part of an effort to increase in situ thermal reserves in order to realize the full generation capacity of the AGF, extensive surface geophysical coverage has been obtained over the AGF and the prospective Chipilapa area to the east. The geophysical surveys were performed to determine physical property characteristics of the known reservoir and then to search for similar characteristics in the Chipilapa area. A secondary objective was to evaluate the surface recharge area in the highlands to the south of the AGF. The principal surface electrical geophysical methods used during this period were DC resistivity and magnetotellurics. Three available data sets have been reinterpreted using drillhole control to help form geophysical models of the area. The geophysical models are compared with the geologic interpretations.

  20. Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust

    PubMed Central

    Barone, T. L.; Patts, J. R.; Janisko, S. J.; Colinet, J. F.; Patts, L. D.; Beck, T. W.; Mischler, S. E.

    2016-01-01

    Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine. PMID:26618374

  1. Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust.

    PubMed

    Barone, T L; Patts, J R; Janisko, S J; Colinet, J F; Patts, L D; Beck, T W; Mischler, S E

    2016-01-01

    Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine.

  2. GPR survey, as one of the best geophysical methods for social and industrial needs

    NASA Astrophysics Data System (ADS)

    Chernov, Anatolii

    2016-04-01

    This paper is about ways and methods of applying non-invasive geophysical method - Ground penetrating radar (GPR) survey in different spheres of science, industry, social life and culture. Author would like to show that geological methods could be widely used for solving great variety of industrial, human safety and other problems. In that article, we take GPR survey as an example of such useful geophysical methods. It is a fact that investigation of near surface underground medium is important process, which influence on development of different spheres of science and social life: investigation of near surface geology (layering, spreading of rock types, identification of voids, etc.), hydrogeology (depth to water horizons, their thickness), preparation step for construction of roads and buildings (civil geology, engineering geology), investigation of cultural heritage (burial places, building remains,...), ecological investigations (land slides, variation in underground water level, etc.), glaciology. These tasks can be solved by geological methods, but as usual, geophysical survey takes a lot of time and energy (especially electric current and resistivity methods, seismic survey). Author claims that GPR survey can be performed faster than other geophysical surveys and results of GPR survey are informative enough to make proper conclusions. Some problems even cannot be solved without GPR. For example, identification of burial place (one of author's research objects): results of magnetic and electric resistivity tomography survey do not contain enough information to identify burial place, but according to anomalies on GPR survey radarograms, presence of burial place can be proven. Identification of voids and non-magnetic objects also hardly can be done by another non-invasive geophysics surveys and GPR is applicable for that purpose. GPR can be applied for monitoring of dangerous processes in geological medium under roads, buildings, parks and other places of human

  3. 3D modelling of the electromagnetic response of geophysical targets using the FDTD method

    SciTech Connect

    Debroux, P.S.

    1996-05-01

    A publicly available and maintained electromagnetic finite-difference time domain (FDTD) code has been applied to the forward modelling of the response of 1D, 2D and 3D geophysical targets to a vertical magnetic dipole excitation. The FDTD method is used to analyze target responses in the 1 MHz to 100 MHz range, where either conduction or displacement currents may have the controlling role. The response of the geophysical target to the excitation is presented as changes in the magnetic field ellipticity. The results of the FDTD code compare favorably with previously published integral equation solutions of the response of 1D targets, and FDTD models calculated with different finite-difference cell sizes are compared to find the effect of model discretization on the solution. The discretization errors, calculated as absolute error in ellipticity, are presented for the different ground geometry models considered, and are, for the most part, below 10% of the integral equation solutions. Finally, the FDTD code is used to calculate the magnetic ellipticity response of a 2D survey and a 3D sounding of complicated geophysical targets. The response of these 2D and 3D targets are too complicated to be verified with integral equation solutions, but show the proper low- and high-frequency responses.

  4. Study of Shallow Low-Enthalpy Geothermal Resources Using Integrated Geophysical Methods

    NASA Astrophysics Data System (ADS)

    De Giorgi, Lara; Leucci, Giovanni

    2015-02-01

    The paper is focused on low enthalpy geothermal exploration performed in south Italy and provides an integrated presentation of geological, hydrogeological, and geophysical surveys carried out in the area of municipality of Lecce. Geological and hydrogeological models were performed using the stratigraphical data from 51 wells. A ground-water flow (direction and velocity) model was obtained. Using the same wells data, the ground-water annual temperature was modeled. Furthermore, the ground surface temperature records from ten meteorological stations were studied. This allowed us to obtain a model related to the variations of the temperature at different depths in the subsoil. Integrated geophysical surveys were carried out in order to explore the low-enthalpy geothermal fluids and to evaluate the results of the model. Electrical resistivity tomography (ERT) and self-potential (SP) methods were used. The results obtained upon integrating the geophysical data with the models show a low-enthalpy geothermal resource constituted by a shallow ground-water system.

  5. Study of Shallow Low-Enthalpy Geothermal Resources Using Integrated Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Giorgi, Lara De; Leucci, Giovanni

    2015-02-01

    The paper is focused on low enthalpy geothermal exploration performed in south Italy and provides an integrated presentation of geological, hydrogeological, and geophysical surveys carried out in the area of municipality of Lecce. Geological and hydrogeological models were performed using the stratigraphical data from 51 wells. A ground-water flow (direction and velocity) model was obtained. Using the same wells data, the ground-water annual temperature was modeled. Furthermore, the ground surface temperature records from ten meteorological stations were studied. This allowed us to obtain a model related to the variations of the temperature at different depths in the subsoil. Integrated geophysical surveys were carried out in order to explore the low-enthalpy geothermal fluids and to evaluate the results of the model. Electrical resistivity tomography (ERT) and self-potential (SP) methods were used. The results obtained upon integrating the geophysical data with the models show a low-enthalpy geothermal resource constituted by a shallow ground-water system

  6. New Methods for Personal Exposure Monitoring for Airborne Particles

    PubMed Central

    Koehler, Kirsten A.; Peters, Thomas

    2016-01-01

    Airborne particles have been associated with a range of adverse cardiopulmonary outcomes, which has driven its monitoring at stationary, central sites throughout the world. Individual exposures, however, can differ substantially from concentrations measured at central sites due to spatial variability across a region and sources unique to the individual, such as cooking or cleaning in homes, traffic emissions during commutes, and widely varying sources encountered at work. Personal monitoring with small, battery-powered instruments enables the measurement of an individual’s exposure as they go about their daily activities. Personal monitoring can substantially reduce exposure misclassification and improve the power to detect relationships between particulate pollution and adverse health outcomes. By partitioning exposures to known locations and sources, it may be possible to account for variable toxicity of different sources. This review outlines recent advances in the field of personal exposure assessment for particulate pollution. Advances in battery technology have improved the feasibility of 24-hour monitoring, providing the ability to more completely attribute exposures to microenvironment (e.g., work, home, commute). New metrics to evaluate the relationship between particulate matter and health are also being considered, including particle number concentration, particle composition measures, and particle oxidative load. Such metrics provide opportunities to develop more precise associations between airborne particles and health and may provide opportunities for more effective regulations. PMID:26385477

  7. Comparison of different hand-drying methods: the potential for airborne microbe dispersal and contamination.

    PubMed

    Best, E L; Redway, K

    2015-03-01

    Efficient washing and drying of hands is important in prevention of the transfer of micro-organisms. However, knowledge surrounding the potential for microbial contamination according to hand-drying methods is limited. This study assessed the potential for airborne microbe dispersal during hand drying by four methods (paper towels, roller towel, warm air and jet air dryer) using three different models. The jet air dryer dispersed liquid from users' hands further and over a greater range (up to 1.5m) than the other drying methods (up to 0.75 m), demonstrating the differing potential risks for airborne microbe dissemination, particularly if handwashing is suboptimal.

  8. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hubbard, S.; Rubin, Y.; Murray, C.; Roden, E.; Majer, E.

    2002-12-01

    if they were available from direct measurements or as variables otherwise. To estimate the geochemical parameters, we first assigned a prior model for each variable and a likelihood model for each type of data, which together define posterior probability distributions for each variable on the domain. Since the posterior probability distribution may involve hundreds of variables, we used a Markov Chain Monte Carlo (MCMC) method to explore each variable by generating and subsequently evaluating hundreds of realizations. Results from this case study showed that although geophysical attributes are not necessarily directly related to geochemical parameters, geophysical data could be very useful for providing accurate and high-resolution information about geochemical parameter distribution through their joint and indirect connections with hydrogeological properties such as lithofacies. This case study also demonstrated that MCMC methods were particularly useful for geochemical parameter estimation using geophysical data because they allow incorporation into the procedure of spatial correlation information, measurement errors, and cross correlations among different types of parameters.

  9. Method for measuring the size distribution of airborne rhinovirus

    SciTech Connect

    Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.; Fisk, W.J.

    2002-01-01

    About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber. Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.

  10. Efficiency of Pareto joint inversion of 2D geophysical data using global optimization methods

    NASA Astrophysics Data System (ADS)

    Miernik, Katarzyna; Bogacz, Adrian; Kozubal, Adam; Danek, Tomasz; Wojdyła, Marek

    2016-04-01

    Pareto joint inversion of two or more sets of data is a promising new tool of modern geophysical exploration. In the first stage of our investigation we created software enabling execution of forward solvers of two geophysical methods (2D magnetotelluric and gravity) as well as inversion with possibility of constraining solution with seismic data. In the algorithm solving MT forward solver Helmholtz's equations, finite element method and Dirichlet's boundary conditions were applied. Gravity forward solver was based on Talwani's algorithm. To limit dimensionality of solution space we decided to describe model as sets of polygons, using Sharp Boundary Interface (SBI) approach. The main inversion engine was created using Particle Swarm Optimization (PSO) algorithm adapted to handle two or more target functions and to prevent acceptance of solutions which are non - realistic or incompatible with Pareto scheme. Each inversion run generates single Pareto solution, which can be added to Pareto Front. The PSO inversion engine was parallelized using OpenMP standard, what enabled execution code for practically unlimited amount of threads at once. Thereby computing time of inversion process was significantly decreased. Furthermore, computing efficiency increases with number of PSO iterations. In this contribution we analyze the efficiency of created software solution taking under consideration details of chosen global optimization engine used as a main joint minimization engine. Additionally we study the scale of possible decrease of computational time caused by different methods of parallelization applied for both forward solvers and inversion algorithm. All tests were done for 2D magnetotelluric and gravity data based on real geological media. Obtained results show that even for relatively simple mid end computational infrastructure proposed solution of inversion problem can be applied in practice and used for real life problems of geophysical inversion and interpretation.

  11. Methods and spatial extent of geophysical Investigations, Mono Lake, California, 2009 to 2011

    USGS Publications Warehouse

    Jayko, A.S.; Hart, P.E.; Childs, J. R.; Cormier, M.-H.; Ponce, D.A.; Athens, N.D.; McClain, J.S.

    2013-01-01

    This report summarizes the methods and spatial extent of geophysical surveys conducted on Mono Lake and Paoha Island by U.S. Geological Survey during 2009 and 2011. The surveys include acquisition of new high resolution seismic reflection data, shipborne high resolution magnetic data, and ground magnetic and gravity data on Paoha Island. Several trials to acquire swath bathymetry and side scan sonar were conducted, but were largely unsuccessful likely due to physical properties of the water column and (or) physical properites of the highly organic bottom sediment.

  12. Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

    SciTech Connect

    Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.; USA, Richland Washington; Bonneville, Alain; USA, Richland Washington; Sullivan, E. Charlotte; USA, Richland Washington; Johnson, Tim C.; USA, Richland Washington; Spane, Frank A.; USA, Richland Washington; Gilmore, Tyler J.; USA, Richland Washington

    2014-12-31

    A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO2 and will be used for: (1) tracking the spatial extent of the free phase CO2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated for a number of geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.

  13. Geophysical Monitoring Methods Evaluation for the FutureGen 2.0 Project

    DOE PAGES

    Strickland, Chris E.; USA, Richland Washington; Vermeul, Vince R.; ...

    2014-12-31

    A comprehensive monitoring program will be needed in order to assess the effectiveness of carbon sequestration at the FutureGen 2.0 carbon capture and storage (CCS) field-site. Geophysical monitoring methods are sensitive to subsurface changes that result from injection of CO2 and will be used for: (1) tracking the spatial extent of the free phase CO2 plume, (2) monitoring advancement of the pressure front, (3) identifying or mapping areas where induced seismicity occurs, and (4) identifying and mapping regions of increased risk for brine or CO2 leakage from the reservoir. Site-specific suitability and cost effectiveness were evaluated for a number ofmore » geophysical monitoring methods including: passive seismic monitoring, reflection seismic imaging, integrated surface deformation, time-lapse gravity, pulsed neutron capture logging, cross-borehole seismic, electrical resistivity tomography, magnetotellurics and controlled source electromagnetics. The results of this evaluation indicate that CO2 injection monitoring using reflection seismic methods would likely be difficult at the FutureGen 2.0 site. Electrical methods also exhibited low sensitivity to the expected CO2 saturation changes and would be affected by metallic infrastructure at the field site. Passive seismic, integrated surface deformation, time-lapse gravity, and pulsed neutron capture monitoring were selected for implementation as part of the FutureGen 2.0 storage site monitoring program.« less

  14. Surrogate-based Multi-Objective Optimization and Uncertainty Quantification Methods for Large, Complex Geophysical Models

    NASA Astrophysics Data System (ADS)

    Gong, Wei; Duan, Qingyun

    2016-04-01

    Parameterization scheme has significant influence to the simulation ability of large, complex dynamic geophysical models, such as distributed hydrological models, land surface models, weather and climate models, etc. with the growing knowledge of physical processes, the dynamic geophysical models include more and more processes and producing more output variables. Consequently the parameter optimization / uncertainty quantification algorithms should also be multi-objective compatible. Although such algorithms have long been available, they usually require a large number of model runs and are therefore computationally expensive for large, complex dynamic models. In this research, we have developed surrogate-based multi-objective optimization method (MO-ASMO) and Markov Chain Monte Carlo method (MC-ASMO) for uncertainty quantification for these expensive dynamic models. The aim of MO-ASMO and MC-ASMO is to reduce the total number of model runs with appropriate adaptive sampling strategy assisted by surrogate modeling. Moreover, we also developed a method that can steer the search process with the help of prior parameterization scheme derived from the physical processes involved, so that all of the objectives can be improved simultaneously. The proposed algorithms have been evaluated with test problems and a land surface model - the Common Land Model (CoLM). The results demonstrated their effectiveness and efficiency.

  15. Handbook of Agricultural Geophysics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods continue to show great promise for use in agriculture. The term “agricultural geophysics” denotes a subdiscipline of geophysics that is focused only on agricultural applications. The Handbook of Agricultural Geophysics was compiled to include a comprehensive overview of the geoph...

  16. EVALUATION OF THREE CLEANING METHODS FOR REMOVING ASBESTOS FROM CARPET. DETERMINATION OF AIRBORNE ASBESTOS CONCENTRATIONS ASSOCIATED WITH EACH METHOD

    EPA Science Inventory

    This study was conducted to compare the effectiveness of three cleaning methods to remove asbestos from contaminated carpet and to determine the airborne asbestos concentrations associated with the use of each method. The carpet on which the methods were tested was naturally cont...

  17. A simple method for vignette correction of airborne digital camera data

    SciTech Connect

    Nguyen, A.T.; Stow, D.A.; Hope, A.S.

    1996-11-01

    Airborne digital camera systems have gained popularity in recent years due to their flexibility, high geometric fidelity and spatial resolution, and fast data turn-around time. However, a common problem that plagues these types of framing systems is vignetting which causes falloff in image brightness away from principle nadir point. This paper presents a simple method for vignetting correction by utilizing laboratory images of a uniform illumination source. Multiple lab images are averaged and inverted to create digital correction templates which then are applied to actual airborne data. The vignette correction was effective in removing the systematic falloff in spectral values. We have shown that the vignette correction is a necessary part of the preprocessing of raw digital airborne remote sensing data. The consequences of not correcting for these effects are demonstrated in the context of monitoring of salt marsh habitat. 4 refs.

  18. Hidden gully erosion - detection and characterization of piping systems using geomorphological and geophysical methods (GPR, ERT)

    NASA Astrophysics Data System (ADS)

    Bernatek-Jakiel, Anita; Kondracka, Marta

    2016-04-01

    The significance of piping in gully formation and hillslope hydrology has been discussed for many years. However, piping as a subsurface erosion caused by water flowing through the soil is still considered as one of the most difficult erosion processes to study, because it occurs below the soil surface and traces of piping become visible on the surface only when a pipe roof collapses, or a pipe inlet or a pipe outlet has been located. Detection of pipes and their complex characterization is still a methodological challenge. Therefore, this study aims at a better detection and characterization of piping systems in a mountainous area under a temperate climate using geomorphological mapping and geophysical methods (ground penetrating radar and electrical resistivity tomography). The survey was carried out in the Bereźnica Wyżna catchment, in the Bieszczady Mts. (Eastern Carpathians, Poland), where pipes develop in Cambisols at a depth ranging from ca 0.70 to 1.00 m. The geomorphological mapping was carried out in the in the whole catchment (2.96 km2), whereas the geophysical survey was limited to two zones (zone A - ca 32 x 82 m, zone B - ca 58 x 115 m). In this study a standard RAMAC GPR system (Malå GeoScience) with shielded 500 MHz antenna was used. The electrical resistivity tomography (ERT) was performed using electrical imaging system LUND with Terrameter SAS 4000 produced by company ABEM. The ERT and GPR data were interpreted in the RES2DINV (Geotomo Software) and RadExplorer software (DECO Geophysical Ltd) respectively. In total, 3 longitudinal and 26 transverse GPR profiles and five ERTs were performed. The used geophysical techniques are shown to be successful in identifying pipes tested in the pilot catchment. Pipes identified by GPR and ERT were verified by the surface indicators (i.e. lowering of surface above pipes). The GPR and ERT applications suggest that piping systems density is much greater than could be detected from surface observation alone

  19. Construction of a groundwater-flow model for the Big Sioux Aquifer using airborne electromagnetic methods, Sioux Falls, South Dakota

    USGS Publications Warehouse

    Valder, Joshua F.; Delzer, Gregory C.; Carter, Janet M.; Smith, Bruce D.; Smith, David V.

    2016-09-28

    The city of Sioux Falls is the fastest growing community in South Dakota. In response to this continued growth and planning for future development, Sioux Falls requires a sustainable supply of municipal water. Planning and managing sustainable groundwater supplies requires a thorough understanding of local groundwater resources. The Big Sioux aquifer consists of glacial outwash sands and gravels and is hydraulically connected to the Big Sioux River, which provided about 90 percent of the city’s source-water production in 2015. Managing sustainable groundwater supplies also requires an understanding of groundwater availability. An effective mechanism to inform water management decisions is the development and utilization of a groundwater-flow model. A groundwater-flow model provides a quantitative framework for synthesizing field information and conceptualizing hydrogeologic processes. These groundwater-flow models can support decision making processes by mapping and characterizing the aquifer. Accordingly, the city of Sioux Falls partnered with the U.S. Geological Survey to construct a groundwater-flow model. Model inputs will include data from advanced geophysical techniques, specifically airborne electromagnetic methods.

  20. Analysis of the applicability of geophysical methods and computer modelling in determining groundwater level

    NASA Astrophysics Data System (ADS)

    Czaja, Klaudia; Matula, Rafal

    2014-05-01

    The paper presents analysis of the possibilities of application geophysical methods to investigation groundwater conditions. In this paper groundwater is defined as liquid water flowing through shallow aquifers. Groundwater conditions are described through the distribution of permeable layers (like sand, gravel, fractured rock) and impermeable or low-permeable layers (like clay, till, solid rock) in the subsurface. GPR (Ground Penetrating Radar), ERT(Electrical Resistivity Tomography), VES (Vertical Electric Soundings) and seismic reflection, refraction and MASW (Multichannel Analysis of Surface Waves) belong to non - invasive, surface, geophysical methods. Due to differences in physical parameters like dielectric constant, resistivity, density and elastic properties for saturated and saturated zones it is possible to use geophysical techniques for groundwater investigations. Few programmes for GPR, ERT, VES and seismic modelling were applied in order to verify and compare results. Models differ in values of physical parameters such as dielectric constant, electrical conductivity, P and S-wave velocity and the density, layers thickness and the depth of occurrence of the groundwater level. Obtained results for computer modelling for GPR and seismic methods and interpretation of test field measurements are presented. In all of this methods vertical resolution is the most important issue in groundwater investigations. This require proper measurement methodology e.g. antennas with frequencies high enough, Wenner array in electrical surveys, proper geometry for seismic studies. Seismic velocities of unconsolidated rocks like sand and gravel are strongly influenced by porosity and water saturation. No influence of water saturation degree on seismic velocities is observed below a value of about 90% water saturation. A further saturation increase leads to a strong increase of P-wave velocity and a slight decrease of S-wave velocity. But in case of few models only the

  1. The generalized cross-validation method applied to geophysical linear traveltime tomography

    NASA Astrophysics Data System (ADS)

    Bassrei, A.; Oliveira, N. P.

    2009-12-01

    The oil industry is the major user of Applied Geophysics methods for the subsurface imaging. Among different methods, the so-called seismic (or exploration seismology) methods are the most important. Tomography was originally developed for medical imaging and was introduced in exploration seismology in the 1980's. There are two main classes of geophysical tomography: those that use only the traveltimes between sources and receivers, which is a cinematic approach and those that use the wave amplitude itself, being a dynamic approach. Tomography is a kind of inverse problem, and since inverse problems are usually ill-posed, it is necessary to use some method to reduce their deficiencies. These difficulties of the inverse procedure are associated with the fact that the involved matrix is ill-conditioned. To compensate this shortcoming, it is appropriate to use some technique of regularization. In this work we make use of regularization with derivative matrices, also called smoothing. There is a crucial problem in regularization, which is the selection of the regularization parameter lambda. We use generalized cross validation (GCV) as a tool for the selection of lambda. GCV chooses the regularization parameter associated with the best average prediction for all possible omissions of one datum, corresponding to the minimizer of GCV function. GCV is used for an application in traveltime tomography, where the objective is to obtain the 2-D velocity distribution from the measured values of the traveltimes between sources and receivers. We present results with synthetic data, using a geological model that simulates different features, like a fault and a reservoir. The results using GCV are very good, including those contaminated with noise, and also using different regularization orders, attesting the feasibility of this technique.

  2. Detection of airborne microbes in a composting facility by cultivation based and cultivation-independent methods.

    PubMed

    Albrecht, Andreas; Witzenberger, Reinhard; Bernzen, Ulrike; Jäckel, Udo

    2007-01-01

    Standard methods for quantification of airborne bacteria are based on cultivation and counting of grown colonies. From complex natural environments it is known that only a small fraction of the total number of cells can be cultivated on routinely used agar-media. Direct microscopic cell counting after DNA-staining usually generates higher concentrations of one to two magnitudes. The objective of the presented study was to compare the concentrations of airborne bacteria sampled in a composting facility by using for any sample the cultivation on trytic soy agar (TSA)--agar, as well as direct counting after DAPI-staining. The concentrations after counting grown colonies were within a range of 10(5)-10(7) cfu m(-3). Concentrations of direct counted cells ranged between 10(6)-10(9) microbes m(-3). In these comparative measurements only 1.5-15.3% of the airborne bacterial cells enumerated by direct counting formed countable colonies after incubation on TSA-agar. Obviously, cultivation based methods underestimate the real amount of airborne microbes. In addition, from literature it is known that inactive or even dead cells can also have the potential to cause health effects. Consequently, a risk assessment based only on measuring colony forming units may, in some cases, not be sufficient.

  3. Analysis of inorganic mercury species associated with airborne particulate matter/aerosols: method development.

    PubMed

    Feng, Xinbin; Lu, Julia Y; Grègoire, D Conrad; Hao, Yingjie; Banic, Catharine M; Schroeder, William H

    2004-10-01

    This paper describes a method for speciation of Hg associated with airborne particulate matter. This method uses a mini-sampler for sample collection and analysis, thermal desorption for separating Hg species, and inductively coupled plasma mass spectrometry (ICP-MS) for identification and quantification of Hg. Coal fly ash spiked with different Hg compounds (e.g. Hg0, HgCl2, HgO, and HgS) was used for qualitative calibration. A standard reference material with a certified value for Hg concentration was used to evaluate the method. When the temperature of the furnace was programmed at a linear rate of increase of 50 degrees min(-1), different Hg compounds could clearly be separated. Three airborne particulate matter samples were collected in parallel in Toronto, ON, Canada and analyzed using this method. Reproducible results were obtained and Hg0, HgCl2, HgO, and HgS species from these samples were detected.

  4. Detection of underground voids in Ohio by use of geophysical methods

    USGS Publications Warehouse

    Munk, Jens; Sheets, R.A.

    1997-01-01

    Geophysical methods are generally classified as electrical, potential field, and seismic methods. Each method type relies on contrasts of physical properties in the subsurface. Forward models based on the physical properties of air- and water-filled voids within common geologic materials indicate that several geophysical methods are technically feasible for detection of subsurface voids in Ohio, but ease of use and interpretation varies widely between the methods. Ground-penetrating radar is the most rapid and cost-effective method for collection of subsurface data in areas associated with voids under roadways. Electrical resistivity, gravity, or seismic reflection methods have applications for direct delineation of voids, but data-collection and analytical procedures are more time consuming. Electrical resistivity, electromagnetic, or magnetic methods may be useful in locating areas where conductive material, such as rail lines, are present in abandoned underground coal mines. Other electrical methods include spontaneous potential and very low frequency (VLF); these latter two methods are considered unlikely candidates for locating underground voids in Ohio. Results of ground-penetrating radar surveys at three highway sites indicate that subsurface penetration varies widely with geologic material type and amount of cultural interference. Two highway sites were chosen over abandoned underground coal mines in eastern Ohio. A third site in western Ohio was chosen in an area known to be underlain by naturally occurring voids in lime stone. Ground-penetrating radar surveys at Interstate 470, in Belmont County, Ohio, indicate subsurface penetration of less than 15 feet over a mined coal seam that was known to vary in depth from 0 to 40 feet. Although no direct observations of voids were made, anomalous areas that may be related to collapse structures above voids were indicated. Cultural interference dominated the radar records at Interstate 70, Guernsey County, Ohio

  5. Infiltration Experiment to Determine Vadose Zone Hydrologic Properties of a Stony Sediment Sequence Incorporating Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Thoma, M. J.; Barrash, W.; Bradford, J. H.

    2011-12-01

    A 5-day infiltration/recovery experiment was conducted in August 2011 at the Boise Hydrogeophysical Research Site (BHRS) to quantify variably-saturated flow behavior and parameterize moisture-tension-hydraulic conductivity relationships in an unconsolidated stony sediment sequence using hydrologic and geophysical methods. It is difficult to study hydrologic properties and behavior of such very coarse sediments in the lab primarily due to difficulty in obtaining coherent and representative samples, and difficulty in establishing effective hydrologic communication between instruments and samples. From geophysical monitoring and coring at the BHRS, we have identified a 5 m x 5 m x 2 m volume with consistent layered stratigraphy and have installed tensiometer nests and a neutron access tube to capture paired profile measurements of tension and moisture content in the vadose zone under natural conditions and during the test. Prior to the experiment, we used drilling logs, core samples, soil tension and moisture profiles, and ground-penetrating radar to determine 3D distribution and lithology of stratigraphic units. Grain-size distribution from core data, laboratory infiltration experiments on core sections, and inversion of tension and moisture response to natural rain events were used to estimate hydraulic properties, including van Genuchten parameters, porosity, and saturated hydraulic conductivity. Pre-test modeling with HYDRUS 1D was used to estimate "rain" application rate and duration required to reach steady-state and predict soil moisture / tension responses. Commercially available water misters were used to apply water over a 2 m by 5 m test area at a constant rate of ~1 cm/hr until steady-state, partially-saturated flow conditions were established through the entire 1.5 m vadose zone. After reaching steady-state, recovery was monitored for 3 days. Wetting front migration during infiltration and soil moisture redistribution after infiltration were observed

  6. The hydrocarbon accumulations mapping in crystalline rocks by mobile geophysical methods

    NASA Astrophysics Data System (ADS)

    Nesterenko, A.

    2013-05-01

    Sedimentary-migration origin theory of hydrocarbons dominates nowadays. However, a significant amount of hydrocarbon deposits were discovered in the crystalline rocks, which corroborates the theory of non-organic origin of hydrocarbons. During the solving of problems of oil and gas exploration in crystalline rocks and arrays so-called "direct" methods can be used. These methods include geoelectric methods of forming short-pulsed electromagnetic field (FSPEF) and vertical electric-resonance sounding (VERS) (FSPEF-VERS express-technology). Use of remote Earth sounding (RES) methods is also actual. These mobile technologies are extensively used during the exploration of hydrocarbon accumulations in crystalline rocks, including those within the Ukrainian crystalline shield. The results of explorations Four anomalous geoelectric zones of "gas condensate reservoir" type were quickly revealed as a result of reconnaissance prospecting works (Fig. 1). DTA "Obukhovychi". Anomaly was traced over a distance of 4 km. Approximate area is 12.0 km2. DTA"Korolevskaya". Preliminary established size of anomalous zone is 10.0 km2. The anomalous polarized layers of gas and gas-condensate type were determined. DTA "Olizarovskaya". Approximate size of anomaly is about 56.0 km2. This anomaly is the largest and the most intense. DTA "Druzhba". Preliminary estimated size of anomaly is 16.0 km2. Conclusions Long experience of a successful application of non-classical geoelectric methods for the solving of variety of practical tasks allow one to state their contribution to the development of a new paradigm of geophysical researches. Simultaneous usage of the remote sensing data processing and interpretation method and FSPEF and VERS technologies can essentially optimize and speed up geophysical work. References 1. S.P. Levashov. Detection and mapping of anomalies of "hydrocarbon deposit" type in the fault zones of crystalline arrays by geoelectric methods. / S.P. Levashov, N.A. Yakymchuk, I

  7. Phase Noise Investigation of Maximum Likelihood Estimation Method for Airborne Multibaseline SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Magnard, C.; Small, D.; Meier, E.

    2015-03-01

    The phase estimation of cross-track multibaseline synthetic aperture interferometric data is usually thought to be very efficiently achieved using the maximum likelihood (ML) method. The suitability of this method is investigated here as applied to airborne single pass multibaseline data. Experimental interferometric data acquired with a Ka-band sensor were processed using (a) a ML method that fuses the complex data from all receivers and (b) a coarse-to-fine method that only uses the intermediate baselines to unwrap the phase values from the longest baseline. The phase noise was analyzed for both methods: in most cases, a small improvement was found when the ML method was used.

  8. Pavement testing by integrated geophysical methods: Feasibility, resolution and diagnostic potential

    NASA Astrophysics Data System (ADS)

    Orlando, Luciana; Cardarelli, Ettore; Cercato, Michele; De Donno, Giorgio; Di Giambattista, Luca

    2017-01-01

    This work is focused on the assessment of the diagnostic potential of several geophysical methods when applied to the investigation of a rigid airport pavement. The potential and limit of each technique are evaluated as well as the added value deriving from their integration. Firstly, we reconstruct a high-resolution image of the pavement by a large electromagnetic and georadar screening. An advanced processing of georadar data, implemented through the picking of the arrival times of reflections for each profile, provides a quantitative estimation of the deviation between the design and the as-built thickness of layers. Additionally, electrical tomography has been applied to unequivocally identify the anomalous zones, where higher values of resistivity would be associated to porous zones that are prone to degradation and failure. The seismic tomographic survey had the additional purpose to recover the mechanical properties of the pavement in terms of both P- and S-waves and consequently of elastic constants (Poisson's ratio), whose values were consistent with those recovered in literature. The anomalies detected by each technique are consistent in their indications and they can be correlated to failure phenomena occurring at layer interfaces within the pavement structure or to unexpected variations of the layer thicknesses. The cost-effective geophysical campaign has validated the four-layered system deduced from the original design and has been used to reconstruct a high-resolution map of the pavement in order to discriminate fractures, crack-prone areas or areas where the as-built differs from the original design.

  9. Cross validation of geotechnical and geophysical site characterization methods: near surface data from selected accelerometric stations in Crete (Greece)

    NASA Astrophysics Data System (ADS)

    Loupasakis, C.; Tsangaratos, P.; Rozos, D.; Rondoyianni, Th.; Vafidis, A.; Kritikakis, G.; Steiakakis, M.; Agioutantis, Z.; Savvaidis, A.; Soupios, P.; Papadopoulos, I.; Papadopoulos, N.; Sarris, A.; Mangriotis, M.-D.; Dikmen, U.

    2015-06-01

    The specification of the near surface ground conditions is highly important for the design of civil constructions. These conditions determine primarily the ability of the foundation formations to bear loads, the stress - strain relations and the corresponding settlements, as well as the soil amplification and corresponding peak ground motion in case of dynamic loading. The static and dynamic geotechnical parameters as well as the ground-type/soil-category can be determined by combining geotechnical and geophysical methods, such as engineering geological surface mapping, geotechnical drilling, in situ and laboratory testing and geophysical investigations. The above mentioned methods were combined, through the Thalis ″Geo-Characterization″ project, for the site characterization in selected sites of the Hellenic Accelerometric Network (HAN) in the area of Crete Island. The combination of the geotechnical and geophysical methods in thirteen (13) sites provided sufficient information about their limitations, setting up the minimum tests requirements in relation to the type of the geological formations. The reduced accuracy of the surface mapping in urban sites, the uncertainties introduced by the geophysical survey in sites with complex geology and the 1D data provided by the geotechnical drills are some of the causes affecting the right order and the quantity of the necessary investigation methods. Through this study the gradual improvement on the accuracy of site characterization data is going to be presented by providing characteristic examples from a total number of thirteen sites. Selected examples present sufficiently the ability, the limitations and the right order of the investigation methods.

  10. Basis and methods of NASA airborne topographic mapper lidar surveys for coastal studies

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Sallenger, Asbury H.; Krabill, William B.; Swift, Robert N.

    2002-01-01

    This paper provides an overview of the basic principles of airborne laser altimetry for surveys of coastal topography, and describes the methods used in the acquisition and processing of NASA Airborne Topographic Mapper (ATM) surveys that cover much of the conterminous US coastline. This form of remote sensing, also known as "topographic lidar", has undergone extremely rapid development during the last two decades, and has the potential to contribute within a wide range of coastal scientific investigations. Various airborne laser surveying (ALS) applications that are relevant to coastal studies are being pursued by researchers in a range of Earth science disciplines. Examples include the mapping of "bald earth" land surfaces below even moderately dense vegetation in studies of geologic framework and hydrology, and determination of the vegetation canopy structure, a key variable in mapping wildlife habitats. ALS has also proven to be an excellent method for the regional mapping of geomorphic change along barrier island beaches and other sandy coasts due to storms or long-term sedimentary processes. Coastal scientists are adopting ALS as a basic method in the study of an array of additional coastal topics. ALS can provide useful information in the analysis of shoreline change, the prediction and assessment of landslides along seacliffs and headlands, examination of subsidence causing coastal land loss, and in predicting storm surge and tsunami inundation.

  11. Methods for describing airborne fractions of free fall spills of powders and liquids

    SciTech Connect

    Ballinger, M.Y.; Buck, J.W.; Owczarski, P.C.; Ayer, J.E.

    1988-01-01

    Pacific Northwest Laboratory developed calculational methods to characterize aerosols produced in hypothetical spill accidents. These methods were developed for the US Nuclear Regulatory Commission to use when evaluating the consequence of postulated accidents for safety analyses and environmental impact statements. Basic physical properties and mechanistic descriptions of spill events were used as a basis for the methods. Source term models consist of equations that can be used to estimate the mass airborne and particle size distribution of aerosols produced by spills of powders and solutions. Experimental data from Sutter et al. (1981) and Ballinger and Hodgson (1986) were emphasized in the models. Parameter ranges for this data were spill height 1 to 3 m, powder mass 25 to 1000 g, and liquid volume 125 to 1000 ml. Liquids spilled included slurries and solutions of varying viscosities. Liquid spills differed from powders in that an aerosol was produced on impact instead of during the fall. The fraction airborne from liquid spills (including viscous solutions and slurries) correlated well with three dimensionless numbers: the Archimedes number, the Froude number, and a density ratio. Liquid aerosol parameters were statistical descriptions of the log-normal distributions. A computer code was developed to model powder spills. In the code, the mass airborne was assumed proportional to the drag force on the power as it falls. The proportionality factor was empirically found to be a function of a dimensionless number, the Galileo number. 16 refs., 2 figs., 13 tabs.

  12. Combined geophysical methods for mapping infiltration pathways at the Aurora Water Aquifer recharge and recovery site

    NASA Astrophysics Data System (ADS)

    Jasper, Cameron A.

    Although aquifer recharge and recovery systems are a sustainable, decentralized, low cost, and low energy approach for the reclamation, treatment, and storage of post- treatment wastewater, they can suffer from poor infiltration rates and the development of a near-surface clogging layer within infiltration ponds. One such aquifer recharge and recovery system, the Aurora Water site in Colorado, U.S.A, functions at about 25% of its predicted capacity to recharge floodplain deposits by flooding infiltration ponds with post-treatment wastewater extracted from river bank aquifers along the South Platte River. The underwater self-potential method was developed to survey self-potential signals at the ground surface in a flooded infiltration pond for mapping infiltration pathways. A method for using heat as a groundwater tracer within the infiltration pond used an array of in situ high-resolution temperature sensing probes. Both relatively positive and negative underwater self-potential anomalies are consistent with observed recovery well pumping rates and specific discharge estimates from temperature data. Results from electrical resistivity tomography and electromagnetics surveys provide consistent electrical conductivity distributions associated with sediment textures. A lab method was developed for resistivity tests of near-surface sediment samples. Forward numerical modeling synthesizes the geophysical information to best match observed self- potential anomalies and provide permeability distributions, which is important for effective aquifer recharge and recovery system design, and optimization strategy development.

  13. Identification of mafic-ultramafic rocks using fuzzy logic classification of airborne geophysical data in the Anapu-Tuer" region, Brazilian Amazon

    NASA Astrophysics Data System (ADS)

    de C. Carneiro, Cleyton; Crósta, Alvaro P.; Silva, Adalene M.; de M. Barros, Carlos Eduardo

    2008-10-01

    The Anapu-Tuer" region, in the Brazilian Amazon, is known for the occurrence of mineral deposits associated with mafic-ultramafic rocks. The spatial distribution of these rocks was investigated by integrating airborne magnetic and gamma ray spectrometry data using Geographic Information System (GIS) and fuzzy logic classification. Highest values of relevance fuzzy were associated with mafic-ultramafic rocks mapped regionally by the Brazilian Geological Survey (CPRM). Furthermore, mineral occurrences mapped by the CPRM showed good spatial correlation with the higher values of relevance fuzzy presented in this paper.

  14. Personal sampling of airborne particles: method performance and data quality.

    PubMed

    Janssen, N A; Hoek, G; Harssema, H; Brunekreef, B

    1998-01-01

    A study of personal exposure to respirable particles (PM10) and fine particles (FP) was conducted in groups of 50-70 year-old adults and primary school children in the Netherlands. Four to eight personal measurements per subject were conducted, on weekdays only. Averaging time was 24 hours. Method performance was evaluated regarding compliance, flow, weighing procedure, field blanks and co-located operation of the personal samplers with stationary methods. Furthermore, the possibility that subjects change their behavior due to the wearing of personal sampling equipment was studied by comparing time activity on days of personal sampling with time activity other weekdays. Compliance was high; 95% of the subjects who agreed to continue participating after the first measurement, successfully completed the study, and, expect for the first two days of FP sampling, over 90% of all personal measurements were successful. All pre and post sampling flow readings were within 10% of the required flow rate of 4 L/min. For PM10 precision of the gravimetric analyses was 2.8 microgram/m3 and 0.7 micrograms/m3 for filters weighted on an analytical and a micro-balance respectively. The detection limit was 10.8 micrograms/m3 and 8.6 micrograms/m3 respectively. For FP, weighing precision was 0.4 micrograms/m3 and the detection limit was 5.3 micrograms/m3. All measurements were above the detection limit. Co-located operation of the personal sampler with stationary samplers gave highly correlated concentration (R > 0.90). Outdoor PM10 concentrations measured with the personal sampler were on average 4% higher compared to a Sierra Anderson (SA) inlet and 9% higher compared to a PM10 Harvard Impactor (HI). With the FP cyclone 6% higher classroom concentrations were measured compared to a PM2.5 HI. Adults spent significantly less time outdoor (0.5 hour) and more time at home (0.9 hour) on days of personal sampling compared to other weekdays. For children no significant differences in time

  15. Fast 3D inversion of airborne gravity-gradiometry data using Lanczos bidiagonalization method

    NASA Astrophysics Data System (ADS)

    Meng, Zhaohai; Li, Fengting; Zhang, Dailei; Xu, Xuechun; Huang, Danian

    2016-09-01

    We developed a new fast inversion method for to process and interpret airborne gravity gradiometry data, which was based on Lanczos bidiagonalization algorithm. Here, we describe the application of this new 3D gravity gradiometry inversion method to recover a subsurface density distribution model from the airborne measured gravity gradiometry anomalies. For this purpose, the survey area is divided into a large number of rectangular cells with each cell possessing a constant unknown density. It is well known that the solution of large linear gravity gradiometry is an ill-posed problem since using the smoothest inversion method is considerably time consuming. We demonstrate that the Lanczos bidiagonalization method can be an appropriate algorithm to solve a Tikhonov solver time cost function for resolving the large equations within a short time. Lanczos bidiagonalization is designed to make the very large gravity gradiometry forward modeling matrices to become low-rank, which will considerably reduce the running time of the inversion method. We also use a weighted generalized cross validation method to choose the appropriate Tikhonov parameter to improve inversion results. The inversion incorporates a model norm that allows us to attain the smoothing and depth of the solution; in addition, the model norm counteracts the natural decay of the kernels, which concentrate at shallow depths. The method is applied on noise-contaminated synthetic gravity gradiometry data to demonstrate its suitability for large 3D gravity gradiometry data inversion. The airborne gravity gradiometry data from the Vinton Salt Dome, USE, were considered as a case study. The validity of the new method on real data is discussed with reference to the Vinton Dome inversion result. The intermediate density values in the constructed model coincide well with previous results and geological information. This demonstrates the validity of the gravity gradiometry inversion method.

  16. Performance of three reflectance calibration methods for airborne hyperspectral spectrometer data.

    PubMed

    Miura, Tomoaki; Huete, Alfredo R

    2009-01-01

    In this study, the performances and accuracies of three methods for converting airborne hyperspectral spectrometer data to reflectance factors were characterized and compared. The "reflectance mode (RM)" method, which calibrates a spectrometer against a white reference panel prior to mounting on an aircraft, resulted in spectral reflectance retrievals that were biased and distorted. The magnitudes of these bias errors and distortions varied significantly, depending on time of day and length of the flight campaign. The "linear-interpolation (LI)" method, which converts airborne spectrometer data by taking a ratio of linearly-interpolated reference values from the preflight and post-flight reference panel readings, resulted in precise, but inaccurate reflectance retrievals. These reflectance spectra were not distorted, but were subject to bias errors of varying magnitudes dependent on the flight duration length. The "continuous panel (CP)" method uses a multi-band radiometer to obtain continuous measurements over a reference panel throughout the flight campaign, in order to adjust the magnitudes of the linear-interpolated reference values from the preflight and post-flight reference panel readings. Airborne hyperspectral reflectance retrievals obtained using this method were found to be the most accurate and reliable reflectance calibration method. The performances of the CP method in retrieving accurate reflectance factors were consistent throughout time of day and for various flight durations. Based on the dataset analyzed in this study, the uncertainty of the CP method has been estimated to be 0.0025 ± 0.0005 reflectance units for the wavelength regions not affected by atmospheric absorptions. The RM method can produce reasonable results only for a very short-term flight (e.g., < 15 minutes) conducted around a local solar noon. The flight duration should be kept shorter than 30 minutes for the LI method to produce results with reasonable accuracies. An important

  17. Detection of Hazardous Cavities Below a Road Using Combined Geophysical Methods

    NASA Astrophysics Data System (ADS)

    De Giorgi, L.; Leucci, G.

    2014-07-01

    Assessment of the risk arising from near-surface natural hazard is a crucial step in safeguarding the security of the roads in karst areas. It helps authorities and other related parties to apply suitable procedures for ground treatment, mitigate potential natural hazards and minimize human and economic losses. Karstic terrains in the Salento Peninsula (Apulia region—South Italy) is a major challenge to engineering constructions and roads due to extensive occurrence of cavities and/or sinkholes that cause ground subsidence and both roads and building collapse. Cavities are air/sediment-filled underground voids, commonly developed in calcarenite sedimentary rocks by the infiltration of rainwater into the ground, opening up, over a long period of time, holes and tunnels. Mitigation of natural hazards can best be achieved through careful geoscientific studies. Traditionally, engineers use destructive probing techniques for the detection of cavities across regular grids or random distances. Such probing is insufficient on its own to provide confidence that cavities will not be encountered. Frequency of probing and depth of investigation may become more expensive. Besides, probing is intrusive, non-continuous, slow, expensive and cannot provide a complete lateral picture of the subsurface geology. Near-surface cavities usually can be easily detected by surface geophysical methods. Traditional and recently developed measuring techniques in seismic, geoelectrics and georadar are suitable for economical investigation of hazardous, potentially collapsing cavities. The presented research focused on an integrated geophysical survey that was carried out in a near-coast road located at Porto Cesareo, a small village a few kilometers south west of Lecce (south Italy). The roads in this area are intensively affected by dangerous surface cracks that cause structural instability. The survey aimed to image the shallow subsurface structures, including karstic features, and evaluate

  18. Use of surface-geophysical methods to assess riverbed scour at bridge piers

    USGS Publications Warehouse

    Gorin, S.R.; Haeni, F.P.

    1989-01-01

    A ground-penetrating-radar system, and three seismic systems--color fathometer, tuned transducer, and black-and-white fathometer--were used to evaluate river-bed scour at the Charter Oak, Founder 's and Bulkeley Bridges in Hartford, Connecticut. Cross-sections of the channel and some lateral sections were run at each bridge in June and July 1987, and significant scour at piers supporting each of these bridges was recorded. Each of the four geophysical systems proved to have advantages and limitations. The ground penetrating radar system used single and dual 80 megahertz antennae floating in the water to transmit and receive the signal. The method was successful in water less than 25 ft deep, and in resistive earth materials. The geometry of existing scour holes and the extent of post-scour sedimentation were clearly defined. The color fathometer, operating at a signal frequency of 20 kilohertz, delineated existing scour-hole geometry, detected infilling of scour holes, and provided qualitative information about the physical properties of sediments. The tuned transducer, operating at a signal frequency of 14 kilohertz, defined scour-hole geometry and the extent of post-scour sediment deposition. Both of these systems were effective in water greater than 5 ft deep. At a signal frequency of 200 kilohertz, the black-and-white fathometer could not penetrate post-scour deposits, but it was useful in defining existing scour-holed geometry in water of any depth. (USGS)

  19. Non-destructive tree root detection with geophysical methods in urban soils

    NASA Astrophysics Data System (ADS)

    Vianden, Mitja Johannes; Weihs, Ulrich; Kuhnke, Falko; Rust, Steffen

    2010-05-01

    To assess the safety of roadside trees or as part of ecophysiological research it is often important to investigate the spatial distribution and development of tree roots. Conventionally this is done by laborious excavations or by the application of root drills which in many cases do not allow a comprehensive data collection. An indirect method for the investigation of subsurface features is ground penetrating radar (GPR). Its ability to detect tree roots has been shown by several studies (for example Hruska et al. 1999; Butnor et al. 2001; Barton et al. 2004). Another geophysical method which has been successful applied to study different aspects of tree roots is electrical resistivity tomography (ERT) (for example Hagrey 2007; Amato et al. 2008). These former studies by other authors mainly concentrated on a correlation between the measured parameters (signal amplitude and resistivity) and root-biomass on forest sites or controlled conditions. Results of Cermak et al. (2000), studying tree roots in urban areas with GPR, indicated that this method may also be useful for anthropogenic influenced areas. As a continuation of these approaches the authors have been using both techniques to study the spatial root architecture of urban trees. This research is designed to elicit the possibilities and limitations of the methods in urban areas. Reference sites have been established to quantify the methods' resolution and assess possible fields of application. These test site measurements are the basis for the interpretation of results at urban tree sites. Their results highlight the importance of 3D-measurements in urban areas because in inhomogeneous soil other reflectors (like rocks, cables, pipes, etc.) cause similar signals and bear a risk of misinterpretation. This can be minimized if detected objects have a spatial continuation and are connected to a tree. Here we present preliminary results from a combined application of both methods at the river bank of the

  20. Improved method for estimating tree crown diameter using high-resolution airborne data

    NASA Astrophysics Data System (ADS)

    Brovkina, Olga; Latypov, Iscander Sh.; Cienciala, Emil; Fabianek, Tomas

    2016-04-01

    Automatic mapping of tree crown size (radius, diameter, or width) from remote sensing can provide a major benefit for practical and scientific purposes, but requires the development of accurate methods. This study presents an improved method for average tree crown diameter estimation at a forest plot level from high-resolution airborne data. The improved method consists of the combination of a window binarization procedure and a granulometric algorithm, and avoids the complicated crown delineation procedure that is currently used to estimate crown size. The systematic error in average crown diameter estimates is corrected with the improved method. The improved method is tested with coniferous, beech, and mixed-species forest plots based on airborne images of various spatial resolutions. The absolute (quantitative) accuracy of the improved crown diameter estimates is comparable or higher for both monospecies plots and mixed-species plots than the current methods. The ability of the improved method to produce good estimates for average crown diameters for monoculture and mixed species, to use remote sensing data of various spatial resolution and to operate in automatic mode promisingly suggests its applicability to a wide range of forest systems.

  1. IGY to IPY, the U.S. Antarctic oversnow and airborne geophysical-glaciological research program from 1957 to 1964 from the view of a young graduate student

    USGS Publications Warehouse

    Behrendt, John C.

    2007-01-01

    When 12 countries established scientific stations in Antarctica for the 1957-58 (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was in the future. The only major field project of the U.S. IGY Antarctic program was series of oversnow traverses, starting in 1957, making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies. The U.S.S.R. and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue and the possibility of mineral resources, the oversnow traverse parties did geologic work, during which unknown mountains were discovered. The oversnow traverses continued through 1966 and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as the mean annual temperature of that era and snow accumulation.

  2. Automated extraction of absorption features from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Geophysical and Environmental Research Imaging Spectrometer (GERIS) data

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Calvin, Wendy M.; Seznec, Olivier

    1988-01-01

    Automated techniques were developed for the extraction and characterization of absorption features from reflectance spectra. The absorption feature extraction algorithms were successfully tested on laboratory, field, and aircraft imaging spectrometer data. A suite of laboratory spectra of the most common minerals was analyzed and absorption band characteristics tabulated. A prototype expert system was designed, implemented, and successfully tested to allow identification of minerals based on the extracted absorption band characteristics. AVIRIS spectra for a site in the northern Grapevine Mountains, Nevada, have been characterized and the minerals sericite (fine grained muscovite) and dolomite were identified. The minerals kaolinite, alunite, and buddingtonite were identified and mapped for a site at Cuprite, Nevada, using the feature extraction algorithms on the new Geophysical and Environmental Research 64 channel imaging spectrometer (GERIS) data. The feature extraction routines (written in FORTRAN and C) were interfaced to the expert system (written in PROLOG) to allow both efficient processing of numerical data and logical spectrum analysis.

  3. An airborne acoustic method to reconstruct a dynamically rough flow surface.

    PubMed

    Krynkin, Anton; Horoshenkov, Kirill V; Van Renterghem, Timothy

    2016-09-01

    Currently, there is no airborne in situ method to reconstruct with high fidelity the instantaneous elevation of a dynamically rough surface of a turbulent flow. This work proposes a holographic method that reconstructs the elevation of a one-dimensional rough water surface from airborne acoustic pressure data. This method can be implemented practically using an array of microphones deployed over a dynamically rough surface or using a single microphone which is traversed above the surface at a speed that is much higher than the phase velocity of the roughness pattern. In this work, the theory is validated using synthetic data calculated with the Kirchhoff approximation and a finite difference time domain method over a number of measured surface roughness patterns. The proposed method is able to reconstruct the surface elevation with a sub-millimeter accuracy and over a representatively large area of the surface. Since it has been previously shown that the surface roughness pattern reflects accurately the underlying hydraulic processes in open channel flow [e.g., Horoshenkov, Nichols, Tait, and Maximov, J. Geophys. Res. 118(3), 1864-1876 (2013)], the proposed method paves the way for the development of non-invasive instrumentation for flow mapping and characterization that are based on the acoustic holography principle.

  4. "Geo-statistics methods and neural networks in geophysical applications: A case study"

    NASA Astrophysics Data System (ADS)

    Rodriguez Sandoval, R.; Urrutia Fucugauchi, J.; Ramirez Cruz, L. C.

    2008-12-01

    The study is focus in the Ebano-Panuco basin of northeastern Mexico, which is being explored for hydrocarbon reservoirs. These reservoirs are in limestones and there is interest in determining porosity and permeability in the carbonate sequences. The porosity maps presented in this study are estimated from application of multiattribute and neural networks techniques, which combine geophysics logs and 3-D seismic data by means of statistical relationships. The multiattribute analysis is a process to predict a volume of any underground petrophysical measurement from well-log and seismic data. The data consist of a series of target logs from wells which tie a 3-D seismic volume. The target logs are neutron porosity logs. From the 3-D seismic volume a series of sample attributes is calculated. The objective of this study is to derive a set of attributes and the target log values. The selected set is determined by a process of forward stepwise regression. The analysis can be linear or nonlinear. In the linear mode the method consists of a series of weights derived by least-square minimization. In the nonlinear mode, a neural network is trained using the select attributes as inputs. In this case we used a probabilistic neural network PNN. The method is applied to a real data set from PEMEX. For better reservoir characterization the porosity distribution was estimated using both techniques. The case shown a continues improvement in the prediction of the porosity from the multiattribute to the neural network analysis. The improvement is in the training and the validation, which are important indicators of the reliability of the results. The neural network showed an improvement in resolution over the multiattribute analysis. The final maps provide more realistic results of the porosity distribution.

  5. New Geophysical Technique for Mineral Exploration and Mineral Discrimination Based on Electromagnetic Methods

    SciTech Connect

    Michael S. Zhdanov

    2009-03-09

    The research during the first two years of the project was focused on developing the foundations of a new geophysical technique for mineral exploration and mineral discrimination, based on electromagnetic (EM) methods. The developed new technique is based on examining the spectral induced polarization effects in electromagnetic data using effective-medium theory and advanced methods of 3-D modeling and inversion. The analysis of IP phenomena is usually based on models with frequency dependent complex conductivity distribution. In this project, we have developed a rigorous physical/mathematical model of heterogeneous conductive media based on the effective-medium approach. The new generalized effective-medium theory of IP effect (GEMTIP) provides a unified mathematical method to study heterogeneity, multi-phase structure, and polarizability of rocks. The geoelectrical parameters of a new composite conductivity model are determined by the intrinsic petrophysical and geometrical characteristics of composite media: mineralization and/or fluid content of rocks, matrix composition, porosity, anisotropy, and polarizability of formations. The new GEMTIP model of multi-phase conductive media provides a quantitative tool for evaluation of the type of mineralization, and the volume content of different minerals using electromagnetic data. We have developed a 3-D EM-IP modeling algorithm using the integral equation (IE) method. Our IE forward modeling software is based on the contraction IE method, which improves the convergence rate of the iterative solvers. This code can handle various types of sources and receivers to compute the effect of a complex resistivity model. We have demonstrated that the generalized effective-medium theory of induced polarization (GEMTIP) in combination with the IE forward modeling method can be used for rock-scale forward modeling from grain-scale parameters. The numerical modeling study clearly demonstrates how the various complex resistivity

  6. The U.S. Antarctic Oversnow and Airborne Geophysical-Glaciological Research Program of the International Geophysical Year (IGY) 1957-58 Period from the View of a Research Scientist Participant

    NASA Astrophysics Data System (ADS)

    Behrendt, J. C.

    2005-12-01

    When 12 countries established scientific stations in Antarctica for the 1957-58 International Geophysical Year (IGY), the Cold War was at its height, seven countries had made claims in Antarctica, and the Antarctic Treaty was a few years in the future. The U.S. program was operated by the Navy and territorial claims were secretly made at several locations during the IGY; these were never officially announced and the U.S. remains a non-claimant state. I was a graduate student geophysicist (assistant seismologist) on the unexplored Filchner-Ronne Ice Shelf as part of the only large scale field project of the U.S. program. Starting in 1956, the U.S. began a series of oversnow traverses making seismic reflection ice soundings (and other geophysical measurements) and glaciological studies to determine the thickness and budget of the Antarctic Ice Sheet. The USSR and France made similar traverses coordinated through the IGY. Although geology and topographic mapping were not part of the IGY program because of the claims issue, and the possibility of mineral resources discoveries, the oversnow traverse parties did geologic work where unknown mountains were discovered. The oversnow traverses continued through 1966, and resulted in an excellent first approximation of the snow surface elevation, ice thickness and bed topography of Antarctica, as well as mean annual temperature of that era and snow accumulation. The vacuum tube dictated the logistics of the oversnow traverse program. Seismic equipment including heavy batteries weighed about 500 kg. Therefore a Sno-Cat tracked vehicle was needed to carry this load. Usually three such vehicles were needed for safety. Because about 3-4 l/km of Sno-Cat fuel was consumed, as much as 120 kg/day of fuel was required. A resupply flight could only carry only about 600 kg/flight (varying greatly as to range and type of aircraft), the major air logistic program of the U.S. IGY program were the three oversnow traverses (other than the

  7. Integrating Geophysics, Geology, and Hydrology for Enhanced Hydrogeological Modeling

    NASA Astrophysics Data System (ADS)

    Auken, E.

    2012-12-01

    Geophysical measurements are important for providing information on the geological structure to hydrological models. Regional scale surveys, where several watersheds are mapped at the same time using helicopter borne transient electromagnetic, results in a geophysical model with a very high lateral and vertical resolution of the geological layers. However, there is a bottleneck when it comes to integrating the information from the geophysical models into the hydrological model. This transformation is difficult, because there is not a simple relationship between the hydraulic conductivity needed for the hydrological model and the electrical conductivity measured by the geophysics. In 2012 the Danish Council for Strategic Research has funded a large research project focusing on the problem of integrating geophysical models into hydrological models. The project involves a number of Danish research institutions, consulting companies, a water supply company, as well as foreign partners, USGS (USA), TNO (Holland) and CSIRO (Australia). In the project we will: 1. Use statistical methods to describe the spatial correlation between the geophysical and the lithological/hydrological data; 2. Develop semi-automatic or automatic methods for transforming spatially sampled geophysical data into geological- and/or groundwater-model parameter fields; 3. Develop an inversion method for large-scale geophysical surveys in which the model space is concordant with the hydrological model space 4. Demonstrate the benefits of spatially distributed geophysical data for informing and updating groundwater models and increasing the predictive power of management scenarios. 5. Develop a new receiver system for Magnetic Resonance Sounding data and further enhance the resolution capability of data from the SkyTEM system. 6. In test areas in Denmark, Holland, USA and Australia we will use data from existing airborne geophysical data, hydrological and geological data and also collect new airborne

  8. New Geophysical Technique for Mineral Exploration and Mineral Discrimination Based on Electromagnetic Methods

    SciTech Connect

    Michael S. Zhdanov

    2005-03-09

    The research during the first year of the project was focused on developing the foundations of a new geophysical technique for mineral exploration and mineral discrimination, based on electromagnetic (EM) methods. The proposed new technique is based on examining the spectral induced polarization effects in electromagnetic data using modern distributed acquisition systems and advanced methods of 3-D inversion. The analysis of IP phenomena is usually based on models with frequency dependent complex conductivity distribution. One of the most popular is the Cole-Cole relaxation model. In this progress report we have constructed and analyzed a different physical and mathematical model of the IP effect based on the effective-medium theory. We have developed a rigorous mathematical model of multi-phase conductive media, which can provide a quantitative tool for evaluation of the type of mineralization, using the conductivity relaxation model parameters. The parameters of the new conductivity relaxation model can be used for discrimination of the different types of rock formations, which is an important goal in mineral exploration. The solution of this problem requires development of an effective numerical method for EM forward modeling in 3-D inhomogeneous media. During the first year of the project we have developed a prototype 3-D IP modeling algorithm using the integral equation (IP) method. Our IE forward modeling code INTEM3DIP is based on the contraction IE method, which improves the convergence rate of the iterative solvers. This code can handle various types of sources and receivers to compute the effect of a complex resistivity model. We have tested the working version of the INTEM3DIP code for computer simulation of the IP data for several models including a southwest US porphyry model and a Kambalda-style nickel sulfide deposit. The numerical modeling study clearly demonstrates how the various complex resistivity models manifest differently in the observed EM

  9. Hydrogeophysical characterization of anisotropy in the Biscayne Aquifer using geophysical methods

    NASA Astrophysics Data System (ADS)

    Yeboah-Forson, Albert

    The anisotropy of the Biscayne Aquifer which serves as the source of potable water for Miami-Dade County was investigated by applying geophysical methods. Electrical resistivity imaging, self potential and ground penetration radar techniques were employed in both regional and site specific studies. In the regional study, electrical anisotropy and resistivity variation with depth were investigated with azimuthal square array measurements at 13 sites. The observed coefficient of electrical anisotropy ranged from 1.01 to 1.36. The general direction of measured anisotropy is uniform for most sites and trends W-E or SE-NW irrespective of depth. Measured electrical properties were used to estimate anisotropic component of the secondary porosity and hydraulic anisotropy which ranged from 1 to 11% and 1.18 to 2.83 respectively. 1-D sounding analysis was used to models the variation of formation resistivity with depth. Resistivities decreased from NW (close to the margins of the everglades) to SE on the shores of Biscayne Bay. Porosity calculated from Archie's law, ranged from 18 to 61% with higher values found along the ridge. Higher anisotropy, porosities and hydraulic conductivities were on the Atlantic Coastal Ridge and lower values at low lying areas west of the ridge. The cause of higher anisotropy and porosity is attributed to higher dissolution rates of the oolitic facies of the Miami Formation composing the ridge. The direction of minimum resistivity from this study is similar to the predevelopment groundwater flow direction indicated in published modeling studies. Detailed investigations were carried out to evaluate higher anisotropy at West Perrine Park located on the ridge and Snapper Creek Municipal well field where the anisotropy trend changes with depth. The higher anisotropy is attributed to the presence of solution cavities oriented in the E-SE direction on the ridge. Similarly, the change in hydraulic anisotropy at the well field might be related to

  10. AUTOMATED LEAK DETECTION OF BURIED TANKS USING GEOPHYSICAL METHODS AT THE HANFORD NUCLEAR SITE

    SciTech Connect

    CALENDINE S; SCHOFIELD JS; LEVITT MT; FINK JB; RUCKER DF

    2011-03-30

    At the Hanford Nuclear Site in Washington State, the Department of Energy oversees the containment, treatment, and retrieval of liquid high-level radioactive waste. Much of the waste is stored in single-shelled tanks (SSTs) built between 1943 and 1964. Currently, the waste is being retrieved from the SSTs and transferred into newer double-shelled tanks (DSTs) for temporary storage before final treatment. Monitoring the tanks during the retrieval process is critical to identifying leaks. An electrically-based geophysics monitoring program for leak detection and monitoring (LDM) has been successfully deployed on several SSTs at the Hanford site since 2004. The monitoring program takes advantage of changes in contact resistance that will occur when conductive tank liquid leaks into the soil. During monitoring, electrical current is transmitted on a number of different electrode types (e.g., steel cased wells and surface electrodes) while voltages are measured on all other electrodes, including the tanks. Data acquisition hardware and software allow for continuous real-time monitoring of the received voltages and the leak assessment is conducted through a time-series data analysis. The specific hardware and software combination creates a highly sensitive method of leak detection, complementing existing drywell logging as a means to detect and quantify leaks. Working in an industrial environment such as the Hanford site presents many challenges for electrical monitoring: cathodic protection, grounded electrical infrastructure, lightning strikes, diurnal and seasonal temperature trends, and precipitation, all of which create a complex environment for leak detection. In this discussion we present examples of challenges and solutions to working in the tank farms of the Hanford site.

  11. Mapping Groundwater in an Alpine Drainage with Airborne Electromagnetic Methods and Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Hein, A.; Armstrong, R. S.; Holbrook, W. S.; Parsekian, A.

    2015-12-01

    The rivers that supply water to most of the West rise in the Rocky Mountains. As drought increases across the country, understanding the hydrology of these alpine regions becomes important to assuring water supplies in the future. Near surface geophysics can help in this effort. In this study, resistivity data from an airborne electromagnetic survey in the Snowy Range was analyzed to map groundwater distribution. The EM survey covered an area of approximately 60 km2 to a depth of around 150 m. Nuclear magnetic resonance (NMR) point soundings provided ground truthing by testing whether water was present, at what depth, and how much. The survey area contained vertically dipping metasedimentary rocks, covered in places by unconsolidated glacial and fluvial deposits. The resistivity data showed horizontal variation in water content much more clearly than vertical changes, which were best detected by NMR. To allow for comparisons across different lithologies and depths, resistivity measurements were first log transformed to produce a more normal distribution, then classed by depth and formation and assigned standardized scores using the mean and standard deviation for those classes. To determine the typical appearance of wet areas, points in the near surface were classed as wet or dry based on proximity to surface water. Logistic regression was used to determine the probability that points with a given standardized score were wet. Where a relationship existed between proximity to surface water and conductivity, this information was translated into a map of groundwater distribution at greater depths. NMR soundings provided quantitative measurements of water content, which were used as known points within these horizontal maps to determine the actual water levels being detected.

  12. A new method to measure air-borne pyrogens based on human whole blood cytokine response.

    PubMed

    Kindinger, Ilona; Daneshian, Mardas; Baur, Hans; Gabrio, Thomas; Hofmann, Andreas; Fennrich, Stefan; von Aulock, Sonja; Hartung, Thomas

    2005-03-01

    Air-borne microorganisms, as well as their fragments and components, are increasingly recognized to be associated with pulmonary diseases, e.g. organic dust toxic syndrome, humidifier lung, building-related illness, "Monday sickness." We have previously described and validated a new method for the detection of pyrogenic (fever-inducing) microbial contaminations in injectable drugs, based on the inflammatory reaction of human blood to pyrogens. We have now adapted this test to evaluate the total inflammatory capacity of air samples. Air was drawn onto PTFE membrane filters, which were incubated with human whole blood from healthy volunteers inside the collection device. Cytokine release was measured by ELISA. The test detects endotoxins and non-endotoxins, such as fungal spores, Gram-positive bacteria and their lipoteichoic acid moiety and pyrogenic dust particles with high sensitivity, thus reflecting the total inflammatory capacity of a sample. When air from different surroundings such as working environments and animal housing was assayed, the method yielded reproducible data which correlated with other parameters of microbial burden tested. We further developed a standard material for quantification and showed that this assay can be performed with cryopreserved as well as fresh blood. The method offers a test to measure the integral inflammatory capacity of air-borne microbial contaminations relevant to humans. It could thus be employed to assess air quality in different living and work environments.

  13. Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

    USGS Publications Warehouse

    Williams, John H.; Lane, Jr., John W.; Singha, Kamini; Haeni, F. Peter

    2002-01-01

    An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing.The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

  14. Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

    USGS Publications Warehouse

    Williams, John H.; Lane, Jr., John W.; Singha, Kamini; Haeni, F. Peter

    2002-01-01

    An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing. The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

  15. Comparison of Air Impaction and Electrostatic Dust Collector Sampling Methods to Assess Airborne Fungal Contamination in Public Buildings.

    PubMed

    Normand, Anne-Cécile; Ranque, Stéphane; Cassagne, Carole; Gaudart, Jean; Sallah, Kankoé; Charpin, Denis-André; Piarroux, Renaud

    2016-03-01

    Many ailments can be linked to exposure to indoor airborne fungus. However, obtaining a precise measurement of airborne fungal levels is complicated partly due to indoor air fluctuations and non-standardized techniques. Electrostatic dust collector (EDC) sampling devices have been used to measure a wide range of airborne analytes, including endotoxins, allergens, β-glucans, and microbial DNA in various indoor environments. In contrast, viable mold contamination has only been assessed in highly contaminated environments such as farms and archive buildings. This study aimed to assess the use of EDCs, compared with repeated air-impactor measurements, to assess airborne viable fungal flora in moderately contaminated indoor environments. Indoor airborne fungal flora was cultured from EDCs and daily air-impaction samples collected in an office building and a daycare center. The quantitative fungal measurements obtained using a single EDC significantly correlated with the cumulative measurement of nine daily air impactions. Both methods enabled the assessment of fungal exposure, although a few differences were observed between the detected fungal species and the relative quantity of each species. EDCs were also used over a 32-month period to monitor indoor airborne fungal flora in a hospital office building, which enabled us to assess the impact of outdoor events (e.g. ground excavations) on the fungal flora levels on the indoor environment. In conclusion, EDC-based measurements provided a relatively accurate profile of the viable airborne flora present during a sampling period. In particular, EDCs provided a more representative assessment of fungal levels compared with single air-impactor sampling. The EDC technique is also simpler than performing repetitive air-impaction measures over the course of several consecutive days. EDC is a versatile tool for collecting airborne samples and was efficient for measuring mold levels in indoor environments.

  16. Field evaluation of a sampling and analytical method for environmental levels of airborne hexavalent chromium.

    PubMed

    Sheehan, P; Ricks, R; Ripple, S; Paustenbach, D

    1992-01-01

    Hexavalent chromium, Cr(VI), has been classified as a human respiratory carcinogen. Airborne Cr(VI) emissions are associated with a number of industrial sources including metal plating, tanning, chromite ore processing, and spray painting operations; combustion sources such as automobiles and incinerators; and fugitive dusts from contaminated soil. There has been considerable interest within industry and the regulatory community to assess the potential cancer risks of workers exposed to Cr(VI) at levels substantially below the threshold limit value (TLV) of 50 micrograms/m3. To date, only the workplace sampling and analytical method (National Institute for Occupational Safety and Health [NIOSH] Method 7600) has been validated for measuring airborne Cr(VI), and it can accurately measure concentrations only as low as 500 ng/m3. This paper describes the field evaluation of a sampling and analytical method for the quantitation of airborne Cr(VI) at concentrations 5000 times lower than the current standard method (as low as 0.1 ng/m3). The collection method uses three 500-mL Greenberg-Smith impingers in series, operated at 15 Lpm for 24 hr. All three impingers are filled with 200 mL of a slightly alkaline (pH approximately 8) sodium bicarbonate buffer solution. The results of validation tests showed that both Cr(VI) and trivalent chromium, Cr(III), were stable in the collection medium and that samples may be stored for up to 100 days without appreciable loss of Cr(VI). Method precision based on the pooled coefficient of variation for replicate samples was 10.4%, and method accuracy based on the mean percent recovery of spiked samples was 94%. Both the precision and accuracy of the impinger method were within NIOSH criteria. This method could be used to measure ambient concentrations of Cr(VI) in the workplace caused by fugitive emissions from manufacturing processes or chromium-contaminated soils at workplace concentrations well below the current TLV (50 micrograms/m3

  17. A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels

    NASA Technical Reports Server (NTRS)

    Mcgary, M. C.

    1982-01-01

    The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs.

  18. Analysis of shallow continuous electromagnetic measurements on archaeological sites in southern Austria and comparison with other geophysical methods

    NASA Astrophysics Data System (ADS)

    Niesner, Erich

    2010-05-01

    Aim of this investigation was outlining the potential of continuous electromagnetic measurements by the comparison of the electromagnetic results with other different geophysical methods at known archaeological sites in Carinthia (Southern Austria). In general a very high resolution is necessary to outline the foundations of roman buildings covered by a sedimentary layer of at least half a meter thickness. The electromagnetic prospecting method had been applied within an archaeologically important region, the archaeological remnants of the first roman provincial capital at the Magdalensberg and at the site of the later location of the capital, at Virunum. With the establishment and consolidation of the Roman Empire the Romans needed more settlement space for the fast growing town and also the demands for defence were less - therefore the Romans transferred the provincial capital down to the "Zollfeld" valley northeast of Klagenfurt. Additional to the electromagnetic investigations, geoelectric, magnetic and susceptibility mapping, spontaneous potential surveys, multielectrode tomography (Niesner, Scholger, Leonhardt 2009) and ground penetrating radar (Morawetz 2006) have been employed jointly during the last years. Also visual and infrared aerial pictures had been available from those areas. The work had been done within a collaborative project between the Geophysical Institute of the University of Leoben and the Landesmuseum Kärnten. The fieldwork and part of the interpretation had been done by students of the University of Leoben within summer field camps. Within these surveys various portions of the archaeological sites had been mapped, providing valuable information of this ancient settlement. One of the most important achievements of the past years of close integration work by the archaeological and the geophysical team was the detailed outlining of an early Christian church, dated by the archaeologists to the early time of the Christians (Dolenz, Niesner

  19. An Equivalent Source Method for Modelling the Lithospheric Magnetic Field Using Satellite and Airborne Magnetic Data

    NASA Astrophysics Data System (ADS)

    Kother, L. K.; Hammer, M. D.; Finlay, C. C.; Olsen, N.

    2014-12-01

    We present a technique for modelling the lithospheric magnetic field based on estimation of equivalent potential field sources. As a first demonstration we present an application to magnetic field measurements made by the CHAMP satellite during the period 2009-2010. Three component vector field data are utilized at all latitudes. Estimates of core and large-scale magnetospheric sources are removed from the satellite measurements using the CHAOS-4 model. Quiet-time and night-side data selection criteria are also employed to minimize the influence of the ionospheric field. The model for the remaining lithospheric magnetic field consists of magnetic point sources (monopoles) arranged in an icosahedron grid with an increasing grid resolution towards the airborne survey area. The corresponding source values are estimated using an iteratively reweighted least squares algorithm that includes model regularization (either quadratic or maximum entropy) and Huber weighting. Data error covariance matrices are implemented, accounting for the dependence of data error variances on quasi-dipole latitudes. Results show good consistency with the CM5 and MF7 models for spherical harmonic degrees up to n = 95. Advantages of the equivalent source method include its local nature and the ease of transforming to spherical harmonics when needed. The method can also be applied in local, high resolution, investigations of the lithospheric magnetic field, for example where suitable aeromagnetic data is available. To illustrate this possibility, we present preliminary results from a case study combining satellite measurements and local airborne scalar magnetic measurements of the Norwegian coastline.

  20. Environmental and Engineering Geophysics

    NASA Astrophysics Data System (ADS)

    Sharma, Prem V.

    1997-12-01

    Geophysical imaging methods provide solutions to a wide variety of environmental and engineering problems: protection of soil and groundwater from contamination; disposal of chemical and nuclear waste; geotechnical site testing; landslide and ground subsidence hazard detection; location of archaeological artifacts. This book comprehensively describes the theory, data acquisition and interpretation of all of the principal techniques of geophysical surveying: gravity, magnetic, seismic, self-potential, resistivity, induced polarization, electromagnetic, ground-probing radar, radioactivity, geothermal, and geophysical borehole logging. Each chapter is supported by a large number of richly illustrated case histories. This book will prove to be a valuable textbook for senior undergraduates and postgraduates in environmental and applied geophysics, a supplementary course book for students of geology, engineering geophysics, civil and mining engineering, and a reference work for professional earth scientists, engineers and town planners.

  1. R/V Kilo Moana's New Geophysical Instrumentation, Processing Methods, and Online Data Repository

    NASA Astrophysics Data System (ADS)

    Miller, J. E.; Chandler, M. T.; Taylor, B.; Shor, A.; Ferguson, J. S.; Wessel, P.

    2012-12-01

    In 2012 several upgrades were made to the underway geophysical systems on R/V Kilo Moana, which the University of Hawaii School of Ocean and Earth Science and Technology (SOEST) operates as part of the University-National Oceanographic Laboratory System (UNOLS) fleet. New instrumentation includes a Bell BGM-3 forced feedback-type gravimeter, a Kongsberg EM 122 12-kHz receiver array, and a high resolution 70-100 kHz EM 710 multibeam echo sounder. Multibeam acceptance trials carried out in June by the Multibeam Advisory Committee, Gates Acoustic Services and UH-SOEST found that both sonars are performing within expected levels with ~5x water depth (WD) for the EM 710 system in shallow water and ~19 km swath width at 4,700 m depth (~4x WD) for the EM 122 deep water system. UH-SOEST also took steps this year to fulfill its obligation to make Kilo Moana's geophysical data more accessible to the public. After an audit of Kilo Moana data at SOEST, Lamont's Rolling Deck to Repository (R2R) and the National Geophysical Data Center (NGDC), as of July 2012 all National Science Foundation-funded Kilo Moana multibeam, gravity, magnetics, center beam depth and Acoustic Doppler Current Profiler (ADCP) data have been submitted to R2R and any multibeam data over 2 years old is being transferred to NGDC. Because it had previously been difficult to access some of SOEST's geophysical data, updated data processing routines have been developed for converting raw gravity, magnetics, and centerbeam depth data to NGDC's standard marine data exchange format (MGD77) for archival and dissemination by NGDC. MGD77 files are being generated and inspected using rigorous along-track analytical techniques for ~270 surveys dating from 2002 to the present and are being submitted to NGDC. We are also developing an online data portal to further facilitate access to SOEST data.

  2. Geophysical methods applied to fault characterization and earthquake potential assessment in the Lower Tagus Valley, Portugal

    NASA Astrophysics Data System (ADS)

    Carvalho, João; Cabral, João; Gonçalves, Rui; Torres, Luís; Mendes-Victor, Luís

    2006-06-01

    The study region is located in the Lower Tagus Valley, central Portugal, and includes a large portion of the densely populated area of Lisbon. It is characterized by a moderate seismicity with a diffuse pattern, with historical earthquakes causing many casualties, serious damage and economic losses. Occurrence of earthquakes in the area indicates the presence of seismogenic structures at depth that are deficiently known due to a thick Cenozoic sedimentary cover. The hidden character of many of the faults in the Lower Tagus Valley requires the use of indirect methodologies for their study. This paper focuses on the application of high-resolution seismic reflection method for the detection of near-surface faulting on two major tectonic structures that are hidden under the recent alluvial cover of the Tagus Valley, and that have been recognized on deep oil-industry seismic reflection profiles and/or inferred from the surface geology. These are a WNW-ESE-trending fault zone located within the Lower Tagus Cenozoic basin, across the Tagus River estuary (Porto Alto fault), and a NNE-SSW-trending reverse fault zone that borders the Cenozoic Basin at the W (Vila Franca de Xira-Lisbon fault). Vertical electrical soundings were also acquired over the seismic profiles and the refraction interpretation of the reflection data was carried out. According to the interpretation of the collected data, a complex fault pattern disrupts the near surface (first 400 m) at Porto Alto, affecting the Upper Neogene and (at least for one fault) the Quaternary, with a normal offset component. The consistency with the previous oil-industry profiles interpretation supports the location and geometry of this fault zone. Concerning the second structure, two major faults were detected north of Vila Franca de Xira, supporting the extension of the Vila Franca de Xira-Lisbon fault zone northwards. One of these faults presents a reverse geometry apparently displacing Holocene alluvium. Vertical offsets

  3. Integrated geophysical methods for the characterisation of an archaeological site (Massenzio Basilica — Roman forum, Rome, Italy)

    NASA Astrophysics Data System (ADS)

    Cardarelli, Ettore; Di Filippo, Gerardina

    2009-08-01

    A geophysical study that involved different techniques was carried out with the aim to improve the knowledge of the archaeological site where the Basilica of Maxentius was founded and to discern individual covered structures (foundations). Vertical Electrical Sounding (VES), seismic refraction and Electrical Resistivity Tomography (ERT) studies were performed in the archaeological site. VES and seismic refraction allowed to characterise the main geological formations of the hill where the Basilica was built and to distinguish the concrete floor and backfilling. Electrical data were processed using different algorithms; their results were compared to appraise the inverted models' robustness. ERT inversion algorithms were used to delineate shape and size of a much more complex structure, that were originally expected from archaeological excavation plan. The results of the commercial program were used as a posteriori information to include them in the algorithm proposed by the authors; the sequential use of the programs defined a processing procedure. The integrated use of different geophysical techniques reduced a great deal the intrinsic ambiguities of each method. Direct explorations (boreholes and archaeological excavations) confirmed the geophysical results.

  4. Application of real-time PCR for total airborne bacterial assessment: Comparison with epifluorescence microscopy and culture-dependent methods

    NASA Astrophysics Data System (ADS)

    Rinsoz, Thomas; Duquenne, Philippe; Greff-Mirguet, Guylaine; Oppliger, Anne

    Traditional culture-dependent methods to quantify and identify airborne microorganisms are limited by factors such as short-duration sampling times and inability to count non-culturable or non-viable bacteria. Consequently, the quantitative assessment of bioaerosols is often underestimated. Use of the real-time quantitative polymerase chain reaction (Q-PCR) to quantify bacteria in environmental samples presents an alternative method, which should overcome this problem. The aim of this study was to evaluate the performance of a real-time Q-PCR assay as a simple and reliable way to quantify the airborne bacterial load within poultry houses and sewage treatment plants, in comparison with epifluorescence microscopy and culture-dependent methods. The estimates of bacterial load that we obtained from real-time PCR and epifluorescence methods, are comparable, however, our analysis of sewage treatment plants indicate these methods give values 270-290 fold greater than those obtained by the "impaction on nutrient agar" method. The culture-dependent method of air impaction on nutrient agar was also inadequate in poultry houses, as was the impinger-culture method, which gave a bacterial load estimate 32-fold lower than obtained by Q-PCR. Real-time quantitative PCR thus proves to be a reliable, discerning, and simple method that could be used to estimate airborne bacterial load in a broad variety of other environments expected to carry high numbers of airborne bacteria.

  5. Assessment of the capabilities of the temporal and spatiotemporal ICA method for geophysical signal separation in GRACE data

    NASA Astrophysics Data System (ADS)

    Boergens, Eva; Rangelova, Elena; Sideris, Michael G.; Kusche, Juergen

    2014-05-01

    We investigate the potential of two independent component analysis (ICA) methods, i.e., the temporal and spatiotemporal ICA, for separating geophysical signals in Gravity Recovery and Climate Experiment (GRACE) data. These methods are based on the assumption of the statistical independence of the signals and thus separate the GRACE-observed mass changes into maximal independent signals. These two ICA methods are compared to the conventional principal component analysis (PCA) method. We test the three methods with respect to their ability to separate a periodic hydrological signal from a trend signal originating in the solid Earth or the cryosphere with simulated and Center for Space Research GRACE mass changes for the time period of January 2003 to December 2010. In addition, we investigate whether the methods are capable of separating hydrological annual and semiannual mass variations. It is shown that both ICA methods are superior to PCA when non-Gaussian mass variations are analyzed. Furthermore, the spatiotemporal ICA resolves successfully the lack of full temporal and spatial independence of the geophysical signals observed by GRACE both in global and regional simulation scenarios. Although the temporal and spatiotemporal ICA are nearly equivalent, both superior to PCA in the global GRACE analysis, the spatiotemporal ICA proves to be more efficient in regional applications by recover more reliably the postglacial rebound trend in North America and the bimodal total water storage variability in Africa.

  6. Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium.

    PubMed

    Boiano, J M; Wallace, M E; Sieber, W K; Groff, J H; Wang, J; Ashley, K

    2000-08-01

    A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between

  7. Investigating the Greenland firn aquifer near Helheim Glacier based on geophysical noninvasive methods and in situ measurements

    NASA Astrophysics Data System (ADS)

    Miège, C.; Koenig, L.; Forster, R. R.; Miller, O. L.; Solomon, D. K.; Legchenko, A.; Schmerr, N. C.; Montgomery, L. N.; Brucker, L.

    2015-12-01

    Prior to the onset of seasonal surface melt, widespread perennial aquifers are detected at an average depth of 22 m below the snow surface in the firn of the Greenland ice sheet from airborne radar data. With an elevation range of ~1200-2000 m, the aquifers are mainly located within the percolation zone of the southern and southeastern parts of the ice sheet, in high snow accumulation regions. The impact of the aquifer on Greenland ice sheet hydrology and the direct (or indirect) contribution to sea-level rise remain unconstrained and require further attention. Our study is located on the upper portion of Helheim Glacier in SE Greenland, ~50 km west of the glacier calving front. We first used repeated airborne radar data collected by CReSIS to infer the presence of the firn over the last two decades from missing bed echoes. For 1993-2008, the aquifer remained relatively stable, after 2008 it expanded to higher elevations, and after spring 2012, drainage of its lower-elevation portion is suspected. Based on these initial insights, recent fieldwork was carried out along the surveyed radar line, following an elevation gradient. Geophysical investigation includes seismic refraction and magnetic resonance soundings to complement the radar data and to provide constraints on the base of the aquifer, water volume, and the transition from water-saturated firn to ice. In addition, piezometers and data-logging stations were deployed at point locations to measure hydraulic conductivity, water table vertical fluctuations, and firn temperature. We report on the different techniques used, initial observations made, and present some preliminary interpretations. Water appears to flow laterally in a highly-permeable unconfined aquifer, topographically driven by ice-sheet surface undulations until water encounters local sinks like crevasses. The aquifer impacts on the ice sheet are numerous, including firn densification, alteration of the ice thermal state, and water from the aquifer

  8. Geophysics in INSPIRE

    NASA Astrophysics Data System (ADS)

    Sőrés, László

    2013-04-01

    INSPIRE is a European directive to harmonize spatial data in Europe. Its' aim is to establish a transparent, multidisciplinary network of environmental information by using international standards and OGC web services. Spatial data themes defined in the annex of the directive cover 34 domains that are closely bundled to environment and spatial information. According to the INSPIRE roadmap all data providers must setup discovery, viewing and download services and restructure data stores to provide spatial data as defined by the underlying specifications by 2014 December 1. More than 3000 institutions are going to be involved in the progress. During the data specification process geophysics as an inevitable source of geo information was introduced to Annex II Geology. Within the Geology theme Geophysics is divided into core and extended model. The core model contains specifications for legally binding data provisioning and is going to be part of the Implementation Rules of the INSPIRE directives. To minimize the work load of obligatory data transformations the scope of the core model is very limited and simple. It covers the most essential geophysical feature types that are relevant in economic and environmental context. To fully support the use cases identified by the stake holders the extended model was developed. It contains a wide range of spatial object types for geophysical measurements, processed and interpreted results, and wrapper classes to help data providers in using the Observation and Measurements (O&M) standard for geophysical data exchange. Instead of introducing the traditional concept of "geophysical methods" at a high structural level the data model classifies measurements and geophysical models based on their spatial characteristics. Measurements are classified as geophysical station (point), geophysical profile (curve) and geophysical swath (surface). Generic classes for processing results and interpretation models are curve model (1D), surface

  9. Airborne geophysical surveys used to delineate geological features associated with the M5.8 August 23, 2011 earthquake in Louisa County, Virginia

    NASA Astrophysics Data System (ADS)

    Shah, A. K.; Horton, J. W.; Gilmer, A. K.

    2012-12-01

    The M5.8 August 23, 2011 Louisa County, VA intraplate earthquake was felt by more people than any other in U.S. history not only because of population density, but also because of the associated geology. However, because limited bedrock exposures pose a challenge to geologic mapping efforts and the earthquake hypocenter is located at a depth of ~6 km, many questions remain. Potential field and gamma-ray spectrometry data thus provide key tools for imaging and understanding both shallow and deep subsurface geologic features. In July 2012, the USGS commissioned a high-resolution magnetic, gravity, and radiometric (gamma-ray spectrometry) survey over a 20 km x 25 km area covering the epicenters of the Louisa County earthquake and its aftershocks. The surveys were flown with 200-m line spacing from an altitude of ~120 m above ground, providing up to a 20-fold improvement over regional magnetic and radiometric coverage. Gravity was measured using Sander Geophysics' AIRGrav system, capable of resolving anomalies as narrow as 800 m for the given survey configuration; in most parts of the survey area the spacing of ground stations is ~10-20 stations per 100 km2. Preliminary magnetic and radiometric data show numerous NE-trending linear anomalies within this part of the Appalachian Piedmont Province. These metamorphic and igneous rocks exhibit 200-500 nT magnetic anomalies of width 300-1000 km that are likely to be generated by contrasts between various metavolcanic and metasedimentary rocks such as magnetite-bearing quartzites and felsic to mafic gneisses. Magnetic lows and radiometric highs are observed over several granitoid intrusive bodies such as the Ellisville pluton, the Falmouth Intrusive Suite, and a Paleozoic pegmatite belt. Derivative magnetic maps delineate numerous thin (< 250 m wide) N- NNW-trending linear anomalies, suggesting that Jurassic diabase dikes are much more common in this area than previously mapped. Radiometric data mostly correlate with mapped

  10. Basic exploration geophysics

    SciTech Connect

    Robinson, E.S.

    1988-01-01

    An introduction to geophysical methods used to explore for natural resources and to survey earth's geology is presented in this volume. It is suitable for second-and third-year undergraduate students majoring in geology or engineering and for professional engineering and for professional engineers and earth scientists without formal instruction in geophysics. The author assumes the reader is familiar with geometry, algebra, and trigonometry. Geophysical exploration includes seismic refraction and reflection surveying, electrical resistivity and electromagnetic field surveying, and geophysical well logging. Surveying operations are described in step-by-step procedures and are illustrated by practical examples. Computer-based methods of processing and interpreting data as well as geographical methods are introduced.

  11. Use of geophysical methods to map subsurface features at levee seepage locations

    NASA Astrophysics Data System (ADS)

    Brackett, Thomas C.

    The Great Flood of 2011 caused moderate to severe seepage and piping along the Mississippi River levees in Northwest Mississippi. The aim of this thesis was to implement geophysical techniques at two seepage locations in order to give a better understanding of the causes of underseepage and information on how to mitigate the problem. Sites near Rena Lara in Coahoma County and near Francis in Bolivar County were chosen to conduct this survey. Electrical Resistivity Tomography (ERT) and Electromagnetic Induction (EM) surveys were conducted on and adjacent to levees to identify seepage pathways and any dominant geological features at the sites. Results from geophysical surveys revealed that Francis and Rena Laura each had a prominent geomorphologic feature that was attributing to underseepage. Seepage at Francis was the result of a sand filled channel capped by a clay overburden. Permeable materials at the base of the channel served as a conduit for transporting river water beneath the levee. The seepage surfaced as sand boils where the overlying clay overburden was thin or non-existent. Investigations at the Rena Lara site revealed a large, clay-filled swale extending beneath the levee. The clay within the swale has relatively low horizontal permeability, and concentrated the seepage flow towards more permeable zones on the flanks of the swale. This resulted in the formation of sand boils at the base of the levee. Both geomorphic features at Francis and Rena Lara were identified as surface drainages using remote sensing data. With the assistance of borehole and elevation data, geophysics was successfully used to characterize the features at each site. Properties such as permeability and clay content were derived from responses in electrical conductivity and used to build seepage models at each site. These models will hopefully be considered when determining seepage conditions and mitigation techniques at other sites along the levee.

  12. Imaging 3D geological structure of the Mygdonian basin (Northern Greece) with geological numerical modeling and geophysical methods.

    NASA Astrophysics Data System (ADS)

    Cédric, Guyonnet-Benaize; Fabrice, Hollender; Maria, Manakou; Alexandros, Savvaidis; Elena, Zargli; Cécile, Cornou; Nikolaos, Veranis; Dimitrios, Raptakis; Artemios, Atzemoglou; Pierre-Yves, Bard; Nikolaos, Theodulidis; Kyriazis, Pitilakis; Emmanuelle, Chaljub

    2013-04-01

    workflow, adapted to heterogeneous geological, geophysical and geotechnical data in order to integrate this database in 3D. This database is integrated in 3D in a geomodelling software (gocad). We build 3D surfaces with constraining data, using DSI method (Discrete Smooth Interpolation). This 3D geological model led to the 3D geometry of the main geophysical/geological boundaries (bedrock, boundaries in the sedimentary filling) and to a precise quantification of the 3D volume of the sedimentary filling of the basin. The results of this study will be used in the second phase of the E2VP project for numerical simulations at the scale of the entire Mygdonian basin.

  13. Airborne Gravity Survey and Ground Gravity in Afghanistan: A Website for Distribution of Data

    USGS Publications Warehouse

    Abraham, Jared D.; Anderson, Eric D.; Drenth, Benjamin J.; Finn, Carol A.; Kucks, Robert P.; Lindsay, Charles R.; Phillips, Jeffrey D.; Sweeney, Ronald E.

    2008-01-01

    Afghanistan?s geologic setting suggests significant natural resource potential. Although important mineral deposits and petroleum resources have been identified, much of the country?s potential remains unknown. Airborne geophysical surveys are a well- accepted and cost-effective method for remotely obtaining information of the geological setting of an area. A regional airborne geophysical survey was proposed due to the security situation and the large areas of Afghanistan that have not been covered using geophysical exploration methods. Acting upon the request of the Islamic Republic of Afghanistan Ministry of Mines, the U.S. Geological Survey contracted with the U.S. Naval Research Laboratory to jointly conduct an airborne geophysical and remote sensing survey of Afghanistan. Data collected during this survey will provide basic information for mineral and petroleum exploration studies that are important for the economic development of Afghanistan. Additionally, use of these data is broadly applicable in the assessment of water resources and natural hazards, the inventory and planning of civil infrastructure and agricultural resources, and the construction of detailed maps. The U.S. Geological Survey is currently working in cooperation with the U.S. Agency of International Development to conduct resource assessments of the country of Afghanistan for mineral, energy, coal, and water resources, and to assess geologic hazards. These geophysical and remote sensing data will be used directly in the resource and hazard assessments.

  14. Geophysical Methods for Locating Karst Conduits in Cane Run Watershed, Central Kentucky

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Paylor, R.; Currens, J. C.; Dinger, J. S.

    2009-12-01

    Cane Run watershed in central Kentucky was listed by the Kentucky Division of Water as one of four focus watersheds for clean-up under the State’s nonpoint-source pollution program. This watershed is degraded by pathogens, nutrients, siltation, and organic enrichment. The sources of pollution include both municipal point sources and nonpoint agricultural and nonagricultural sources. The relative contribution of different parts of the watershed to the contamination is not well understood, however. The geology of Cane Run watershed consists of Ordovician thin-bedded limestone with sparse interbeds of shale. The landscape is dominated by karst features such as sinkholes and springs. Cane Run only flows during times of significant rainfall, usually in the spring of the year. The remainder of the year, most water is recharged to a karst conduit system that leads from Lexington, Ky to Royal Spring, as demonstrated by groundwater tracing. Royal Spring is the major water supply for Georgetown in Scott County, Ky. We attempted to locate the karst conduit so that groundwater flowing through the conduit could be monitored. These monitoring data are essential for assessing the effectiveness of remediation plans. In 2008, based on geology, karst features, and hydrogeology, an initial round of electrical-resistivity and spontaneous-potential geophysical surveys were conducted to help pinpoint the location of the conduit at three sites. Fifteen exploratory boreholes were drilled on the basis of the geophysical results. The boreholes confirmed the geophysical surveys had located minor mud-filled conduits that were interpreted as tributaries to the main conduit. Another round of 2D and 3D electrical resistivity surveys were conducted in 2009 to search for the main conduit. The analysis of this round of surveys resulted in one promising site that is suspected to be in close proximity to the conduit. A time-lapse 2D electrical resistivity survey in conjunction with calcium chlorite

  15. Notes on interpretation of geophysical data over areas of mineralization in Afghanistan

    USGS Publications Warehouse

    Drenth, Benjamin J.

    2011-01-01

    Afghanistan has the potential to contain substantial metallic mineral resources. Although valuable mineral deposits have been identified, much of the country's potential remains unknown. Geophysical surveys, particularly those conducted from airborne platforms, are a well-accepted and cost-effective method for obtaining information on the geological setting of a given area. This report summarizes interpretive findings from various geophysical surveys over selected mineral targets in Afghanistan, highlighting what existing data tell us. These interpretations are mainly qualitative in nature, because of the low resolution of available geophysical data. Geophysical data and simple interpretations are included for these six areas and deposit types: (1) Aynak: Sedimentary-hosted copper; (2) Zarkashan: Porphyry copper; (3) Kundalan: Porphyry copper; (4) Dusar Shaida: Volcanic-hosted massive sulphide; (5) Khanneshin: Carbonatite-hosted rare earth element; and (6) Chagai Hills: Porphyry copper.

  16. Preventing Airborne Disease Transmission: Review of Methods for Ventilation Design in Health Care Facilities

    PubMed Central

    Aliabadi, Amir A.; Rogak, Steven N.; Bartlett, Karen H.; Green, Sheldon I.

    2011-01-01

    Health care facility ventilation design greatly affects disease transmission by aerosols. The desire to control infection in hospitals and at the same time to reduce their carbon footprint motivates the use of unconventional solutions for building design and associated control measures. This paper considers indoor sources and types of infectious aerosols, and pathogen viability and infectivity behaviors in response to environmental conditions. Aerosol dispersion, heat and mass transfer, deposition in the respiratory tract, and infection mechanisms are discussed, with an emphasis on experimental and modeling approaches. Key building design parameters are described that include types of ventilation systems (mixing, displacement, natural and hybrid), air exchange rate, temperature and relative humidity, air flow distribution structure, occupancy, engineered disinfection of air (filtration and UV radiation), and architectural programming (source and activity management) for health care facilities. The paper describes major findings and suggests future research needs in methods for ventilation design of health care facilities to prevent airborne infection risk. PMID:22162813

  17. Exploration Geophysics

    ERIC Educational Resources Information Center

    Espey, H. R.

    1977-01-01

    Describes geophysical techniques such as seismic, gravity, and magnetic surveys of offshare acreage, and land-data gathering from a three-dimensional representation made from closely spaced seismic lines. (MLH)

  18. Exploration Geophysics

    ERIC Educational Resources Information Center

    Savit, Carl H.

    1978-01-01

    Expansion of activity and confirmation of new technological directions characterized several fields of exploration geophysics in 1977. Advances in seismic-reflection exploration have been especially important. (Author/MA)

  19. A robust method for estimating the multifractal wavelet spectrum in geophysical images

    NASA Astrophysics Data System (ADS)

    Nicolis, Orietta; Porro, Francesco

    2013-04-01

    The description of natural phenomena by an analysis of the statistical scaling laws is always a popular topic. Many studies aim to identify the fractal feature by estimating the self-similar parameter H, considered constant at different scales of observation. However, most real world data exhibit a multifractal structure, that is, the self-similarity parameter varies erratically with time. The multifractal spectrum provide an efficient tool for characterizing the scaling and singularity structures in signals and images, proving useful in numerous applications such as fluid dynamics, internet network traffic, finance, image analysis, texture synthesis, meteorology, and geophysics. In recent years, the multifractal formalism has been implemented with wavelets. The advantages of using the wavelet-based multifractal spectrum are: the availability of fast algorithms for wavelet transform, the locality of wavelet representations in both time and scale, and intrinsic dyadic self-similarity of basis functions. In this work we propose a robust Wavelet-based Multifractal Spectrum Estimator for the analysis of geophysical signals and satellite images. Finally, a simulation study and examples are considered to test the performances of the estimator.

  20. Soft X-ray-assisted detection method for airborne molecular contaminations (AMCs)

    NASA Astrophysics Data System (ADS)

    Kim, Changhyuk; Zuo, Zhili; Finger, Hartmut; Haep, Stefan; Asbach, Christof; Fissan, Heinz; Pui, David Y. H.

    2015-03-01

    Airborne molecular contaminations (AMCs) represent a wide range of gaseous contaminants in cleanrooms. Due to the unintentional nanoparticle or haze formation as well as doping caused by AMCs, improved monitoring and controlling methods for AMCs are urgent in the semiconductor industry. However, measuring ultra-low concentrations of AMCs in cleanrooms is difficult, especially, behind a gas filter. In this study, a novel detection method for AMCs, which is on-line, economical, and applicable for diverse AMCs, was developed by employing gas-to-particle conversion with soft X-ray, and then measuring the generated nanoparticles. Feasibility study of this method was conducted through the evaluations of granular-activated carbons (GACs), which are widely used AMC filter media. Sulfur dioxide (SO2) was used as an AMC for the feasibility study. Using this method, the ultra-low concentrations of SO2 behind GACs were determined in terms of concentrations of generated sulfuric acid (H2SO4) nanoparticles. By calculating SO2 concentrations from the nanoparticle concentrations using empirical correlation equations between them, remarkable sensitivity of this method to SO2 was shown, down to parts-per-trillions, which are too low to detect using commercial gas sensors. Also, the calculated SO2 concentrations showed good agreement with those measured simultaneously by a commercial SO2 monitor at parts-per-billions.

  1. Development of 3D Geological Structure Analysis Method Using Multi-geophysical Data: Application to Hwasan Caldera in Korea

    NASA Astrophysics Data System (ADS)

    Park, G.; Yang, J.; Yi, M.; Kim, J.; Kwon, B.

    2011-12-01

    Multi-geophysical surveys were carried out around the Hwasan caldera at the Euisung Sub-basin in Korea. To overcome the limitations of survey resolutions of previous studies, 510 points of gravity and 32 points of magnetotelluric (MT) data were obtained. To analyze three-dimensional density and resistivity models, gravity and MT inversions were carried out using Marquardt-Levenberg method and WSINV3DMT code, respectively. To carry out the objective structure analysis of multi-parametric geophysical data, a new classification technique, Structure Index (SI) method, was proposed. SI method consists of Type Angle (TA) and Type Intensity (TI) values. It is one of the projection techniques similar to the universal transverse Mercator (UTM) projection, and a mathematical method of showing the patterns of correlation and abnormalness of physical property values by TA and TI values. TA values indicate the correlation patterns of normalized data sets and TI values show the levels of the abnormalness of physical property values. For the processing, the density and resistivity values were estimated at the same nodes using kriging methods through S-GeMS based on GSLIB. Base on the results of the SI processing, all classified nodes were plotted and visualized in 3-dimensional space as shown in Fig. 1. The analyzed results of SI method using gravity and MT data match well with those of the previous researches, including the geologic map. First, the intrusive igneous rocks, which have high density and resistivity values, were analyzed according to the ring fault and intrusive igneous area at the north-east side of the Hwasan caldera. Second, the pyroclastic rocks at the center of the caldera, which is extended to a depth of around 1 km with low density and resistivity values, were imaged. The basement structure, which has a relatively low resistivity and high density at a depth of 5 km was also inferred by integration analysis. This method makes it possible to classify and three

  2. Near-surface geophysical methods for investigating the Buyukcekmece landslide in Istanbul, Turkey

    NASA Astrophysics Data System (ADS)

    Yalcinkaya, Esref; Alp, Hakan; Ozel, Oguz; Gorgun, Ethem; Martino, Salvatore; Lenti, Luca; Bourdeau, Celine; Bigarre, Pascal; Coccia, Stella

    2016-11-01

    In this study, near-surface geophysical techniques are used to investigate the physical characteristics of the Buyukcekmece landslide (Istanbul, Turkey). The Buyukcekmece landslide has continuous activity at a low velocity and is classified as a complex mechanism. It includes rototranslational parts, several secondary scarps, several landslide terraces, and evidence of two earth flows. It mainly develops in the clayey layers of the Danismen Formation. According to our findings, P-wave velocities ranging from 300 m/s to 2400 m/s do not provide notable discrimination between sliding mass and stable soil. They show variations in blocks reflecting a complex structure. We obtained the S-wave velocity structure of the landslide up to 80 m by combining the analysis of MASW and ReMi. It is clear that S-wave velocities are lower in the landslide compared to those of the stable area. Identical S-wave velocities for the entire area at depths higher than 60 m may point out the maximum thickness of the landslide mass. Resonance frequencies obtained from the H/V analysis of the landslide area are generally higher than those of the stable area. The depths computed by using an empirical relationship between the resonance frequency and the soil thickness point out the failure surfaces from 10 to 50 m moving downslope from the landslide crown area. The resistivity values within the landslide are generally lower than 30 Ω m, i.e., a typical value for remolded clayey debris. The geophysical results reflect an overview of the geological model, but the complexity of the landslide makes it difficult to map the landslide structure in detail.

  3. A wavelet-based baseline drift correction method for grounded electrical source airborne transient electromagnetic signals

    NASA Astrophysics Data System (ADS)

    Wang, Yuan 1Ji, Yanju 2Li, Suyi 13Lin, Jun 12Zhou, Fengdao 1Yang, Guihong

    2013-09-01

    A grounded electrical source airborne transient electromagnetic (GREATEM) system on an airship enjoys high depth of prospecting and spatial resolution, as well as outstanding detection efficiency and easy flight control. However, the movement and swing of the front-fixed receiving coil can cause severe baseline drift, leading to inferior resistivity image formation. Consequently, the reduction of baseline drift of GREATEM is of vital importance to inversion explanation. To correct the baseline drift, a traditional interpolation method estimates the baseline `envelope' using the linear interpolation between the calculated start and end points of all cycles, and obtains the corrected signal by subtracting the envelope from the original signal. However, the effectiveness and efficiency of the removal is found to be low. Considering the characteristics of the baseline drift in GREATEM data, this study proposes a wavelet-based method based on multi-resolution analysis. The optimal wavelet basis and decomposition levels are determined through the iterative comparison of trial and error. This application uses the sym8 wavelet with 10 decomposition levels, and obtains the approximation at level-10 as the baseline drift, then gets the corrected signal by removing the estimated baseline drift from the original signal. To examine the performance of our proposed method, we establish a dipping sheet model and calculate the theoretical response. Through simulations, we compare the signal-to-noise ratio, signal distortion, and processing speed of the wavelet-based method and those of the interpolation method. Simulation results show that the wavelet-based method outperforms the interpolation method. We also use field data to evaluate the methods, compare the depth section images of apparent resistivity using the original signal, the interpolation-corrected signal and the wavelet-corrected signal, respectively. The results confirm that our proposed wavelet-based method is an

  4. Modeling aboveground tree woody biomass using national-scale allometric methods and airborne lidar

    NASA Astrophysics Data System (ADS)

    Chen, Qi

    2015-08-01

    Estimating tree aboveground biomass (AGB) and carbon (C) stocks using remote sensing is a critical component for understanding the global C cycle and mitigating climate change. However, the importance of allometry for remote sensing of AGB has not been recognized until recently. The overarching goals of this study are to understand the differences and relationships among three national-scale allometric methods (CRM, Jenkins, and the regional models) of the Forest Inventory and Analysis (FIA) program in the U.S. and to examine the impacts of using alternative allometry on the fitting statistics of remote sensing-based woody AGB models. Airborne lidar data from three study sites in the Pacific Northwest, USA were used to predict woody AGB estimated from the different allometric methods. It was found that the CRM and Jenkins estimates of woody AGB are related via the CRM adjustment factor. In terms of lidar-biomass modeling, CRM had the smallest model errors, while the Jenkins method had the largest ones and the regional method was between. The best model fitting from CRM is attributed to its inclusion of tree height in calculating merchantable stem volume and the strong dependence of non-merchantable stem biomass on merchantable stem biomass. This study also argues that it is important to characterize the allometric model errors for gaining a complete understanding of the remotely-sensed AGB prediction errors.

  5. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.J.; Keiswetter, D.

    1995-10-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits rapid geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected.

  6. An evaluation of analytical methods, air sampling techniques, and airborne occupational exposure of metalworking fluids.

    PubMed

    Verma, Dave K; Shaw, Don S; Shaw, M Lorraine; Julian, Jim A; McCollin, Shari-Ann; des Tombe, Karen

    2006-02-01

    This article summarizes an assessment of air sampling and analytical methods for both oil and water-based metalworking fluids (MWFs). Three hundred and seventy-four long-term area and personal airborne samples were collected at four plants using total (closed-face) aerosol samplers and thoracic samplers. A direct-reading device (DustTrak) was also used. The processes sampled include steel tube making, automotive component manufacturing, and small part manufacturing in a machine shop. The American Society for Testing and Materials (ASTM) Method PS42-97 of analysis was evaluated in the laboratory. This evaluation included sample recovery, determination of detection limits, and stability of samples during storage. Results of the laboratory validation showed (a) the sample recovery to be about 87%, (b) the detection limit to be 35 microg, and (c) sample stability during storage at room temperature to decline rapidly within a few days. To minimize sample loss, the samples should be stored in a freezer and analyzed within a week. The ASTM method should be the preferred method for assessing metalworking fluids (MWFs). The ratio of thoracic aerosol to total aerosol ranged from 0.6 to 0.7. A similar relationship was found between the thoracic extractable aerosol and total extractable aerosol. The DustTrak, with 10-microm sampling head, was useful in pinpointing the areas of potential exposure. MWF exposure at the four plants ranged from 0.04 to 3.84 mg/m3 with the geometric mean ranging between 0.22 to 0.59 mg/m3. Based on this data and the assumption of log normality, MWF exposures are expected to exceed the National Institute for Occupational Safety and Health recommended exposure limit of 0.5 mg/m3 as total mass and 0.4 mg/m3 as thoracic mass about 38% of the time. In addition to controlling airborne MWF exposure, full protection of workers would require the institution of programs for fluid management and dermal exposure prevention.

  7. [A new counting method for airborne Japanese red cedar and grass pollen allergens by the immunoblotting technique].

    PubMed

    Takahashi, Y; Katagiri, S; Inouye, S; Sakaguchi, M

    1990-12-01

    We devised a new counting method of pollen allergen particles which improved the fluorescence immunoblotting technique by Schumacher et al (1988). And by which airborne pollen allergens became visible under 10X magnifier or naked eyes. Airborne pollen allergens collected on the Burkard's sampling tape were transferred onto nitrocellulose membrane and were reacted with anti Cry j I rabbit serum or anti Lol p I rabbit serum, and then treated with alkaline phosphatase conjugated F(ab')2 anti rabbit IgG. Finally, bluish purple spots were obtained by staining with BCIP/NBT phosphatase substrate system. This technique does not require any skillful morphological observation, and is more suitable to measure the amounts of airborne pollen allergen for given pollinosis patients because total pollen allergen particles with common antigenicity are measured. In Japanese red cedar pollen counts, we could not count the spots more than 400 grains per 0.16 cm2 of the sample trapping area due to many overlapping spots. In this case, we tried to calculate the value from the ratio of bluish purple coloured area to one pollen area. However, a more suitable method for estimating the content of pollinosis caused airborne allergens may be colorimetric quantitation using densitometry and displaying the value as allergen content.

  8. Accuracies of Positioning and Geodata Using Helicopters for Geodetic and Geophysical Surveys

    NASA Astrophysics Data System (ADS)

    Bielenberg, O.; Meyer, U.; Vasterling, M.

    2010-12-01

    : Helicopters are frequently used for airborne surveys in geodesy and geophysics. The range of accuracies needed for proper data reconstruction is wide spread from some meters for airborne magnetics to centimeters for laser scanner measurements. This study lists up to date methods of online and offline positioning, discusses their accuracies that may be achieved and relates them to different geodetic as geophysical surveys in different types of terrain. The goal is to match helicopter positioning methods with the given survey task to optimize results and work efficiency. Some fundamental studies have been conducted on helicopter work during the DESIRE (Dead Sea Integrated Research) project in Israel and Jordan which have been continued in Germany. These studies include the impact of vibrations on INS, IMU and gravity meter systems as well as the choice of antenna locations on the shell of the helicopter.

  9. Particle Geophysics

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyuki K. M.

    2014-05-01

    Geophysics research has long been dominated by classical mechanics, largely disregarding the potential of particle physics to augment existing techniques. The purpose of this article is to review recent progress in probing Earth's interior with muons and neutrinos. Existing results for various volcanological targets are reviewed. Geoneutrinos are also highlighted as examples in which the neutrino probes elucidate the composition of Earth's deep interior. Particle geophysics has the potential to serve as a useful paradigm to transform our understanding of Earth as dramatically as the X-ray transformed our understanding of medicine and the body.

  10. A new method for GPS-based wind speed determinations during airborne volcanic plume measurements

    USGS Publications Warehouse

    Doukas, Michael P.

    2002-01-01

    Begun nearly thirty years ago, the measurement of gases in volcanic plumes is today an accepted technique in volcano research. Volcanic plume measurements, whether baseline gas emissions from quiescent volcanoes or more substantial emissions from volcanoes undergoing unrest, provide important information on the amount of gaseous output of a volcano to the atmosphere. Measuring changes in gas emission rates also allows insight into eruptive behavior. Some of the earliest volcanic plume measurements of sulfur dioxide were made using a correlation spectrometer (COSPEC). The COSPEC, developed originally for industrial pollution studies, is an upward-looking optical spectrometer tuned to the ultraviolet absorption wavelength of sulfur dioxide (Millán and Hoff, 1978). In airborne mode, the COSPEC is mounted in a fixed-wing aircraft and flown back and forth just underneath a volcanic plume, perpendicular to the direction of plume travel (Casadevall and others, 1981; Stoiber and others, 1983). Similarly, for plumes close to the ground, the COSPEC can be mounted in an automobile and driven underneath a plume if a suitable road system is available (Elias and others, 1998). The COSPEC can also be mounted on a tripod and used to scan a volcanic plume from a fixed location on the ground, although the effectiveness of this configuration declines with distance from the plume (Kyle and others, 1990). In the 1990’s, newer airborne techniques involving direct sampling of volcanic plumes with infrared spectrometers and electrochemical sensors were developed in order to measure additional gases such as CO2 and H2S (Gerlach and others, 1997; Gerlach and others, 1999; McGee and others, 2001). These methods involve constructing a plume cross-section from several measurement traverses through the plume in a vertical plane. Newer instruments such as open-path Fourier transform infrared (FTIR) spectrometers are now being used to measure the gases in volcanic plumes mostly from fixed

  11. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-08-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Salt dilution gauging is a traditional and well-documented technique in this respect. The complete mixing of salt used for dilution gauging is required; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, fast electrical resistivity tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross section. With this imaging, complete mixing can be verified. If the mixing is not complete, the image created by FERT can also provide a possible guidance for selecting water-sampling locations in the sampling cross section. A water multi-sampling system prototype aimed to potentially take into account concentration variability is also proposed and tested. The results reported in the paper show that FERT provides a three-dimensional image of the dissolved salt plume and that this can potentially help in the selection of water sampling points.

  12. Alternative statistical methods for interpreting airborne Alder ( Alnus glutimosa (L.) Gaertner) pollen concentrations

    NASA Astrophysics Data System (ADS)

    González Parrado, Zulima; Valencia Barrera, Rosa M.; Fuertes Rodríguez, Carmen R.; Vega Maray, Ana M.; Pérez Romero, Rafael; Fraile, Roberto; Fernández González, Delia

    2009-01-01

    This paper reports on the behaviour of Alnus glutinosa (alder) pollen grains in the atmosphere of Ponferrada (León, NW Spain) from 1995 to 2006. The study, which sought to determine the effects of various weather-related parameters on Alnus pollen counts, was performed using a volumetric method. The main pollination period for this taxon is January-February. Alder pollen is one of the eight major airborne pollen allergens found in the study area. An analysis was made of the correlation between pollen counts and major weather-related parameters over each period. In general, the strongest positive correlation was with temperature, particularly maximum temperature. During each period, peak pollen counts occurred when the maximum temperature fell within the range 9°C-14°C. Finally, multivariate analysis showed that the parameter exerting the greatest influence was temperature, a finding confirmed by Spearman correlation tests. Principal components analysis suggested that periods with high pollen counts were characterised by high maximum temperature, low rainfall and an absolute humidity of around 6 g m-3. Use of this type of analysis in conjunction with other methods is essential for obtaining an accurate record of pollen-count variations over a given period.

  13. Parallel Processing Method for Airborne Laser Scanning Data Using a PC Cluster and a Virtual Grid.

    PubMed

    Han, Soo Hee; Heo, Joon; Sohn, Hong Gyoo; Yu, Kiyun

    2009-01-01

    In this study, a parallel processing method using a PC cluster and a virtual grid is proposed for the fast processing of enormous amounts of airborne laser scanning (ALS) data. The method creates a raster digital surface model (DSM) by interpolating point data with inverse distance weighting (IDW), and produces a digital terrain model (DTM) by local minimum filtering of the DSM. To make a consistent comparison of performance between sequential and parallel processing approaches, the means of dealing with boundary data and of selecting interpolation centers were controlled for each processing node in parallel approach. To test the speedup, efficiency and linearity of the proposed algorithm, actual ALS data up to 134 million points were processed with a PC cluster consisting of one master node and eight slave nodes. The results showed that parallel processing provides better performance when the computational overhead, the number of processors, and the data size become large. It was verified that the proposed algorithm is a linear time operation and that the products obtained by parallel processing are identical to those produced by sequential processing.

  14. Parallel Processing Method for Airborne Laser Scanning Data Using a PC Cluster and a Virtual Grid

    PubMed Central

    Han, Soo Hee; Heo, Joon; Sohn, Hong Gyoo; Yu, Kiyun

    2009-01-01

    In this study, a parallel processing method using a PC cluster and a virtual grid is proposed for the fast processing of enormous amounts of airborne laser scanning (ALS) data. The method creates a raster digital surface model (DSM) by interpolating point data with inverse distance weighting (IDW), and produces a digital terrain model (DTM) by local minimum filtering of the DSM. To make a consistent comparison of performance between sequential and parallel processing approaches, the means of dealing with boundary data and of selecting interpolation centers were controlled for each processing node in parallel approach. To test the speedup, efficiency and linearity of the proposed algorithm, actual ALS data up to 134 million points were processed with a PC cluster consisting of one master node and eight slave nodes. The results showed that parallel processing provides better performance when the computational overhead, the number of processors, and the data size become large. It was verified that the proposed algorithm is a linear time operation and that the products obtained by parallel processing are identical to those produced by sequential processing. PMID:22574032

  15. 137Cs measurement uncertainties and detection limits for airborne gamma spectrometry (AGS) data analysed using a spectral windows method.

    PubMed

    Cresswell, A J; Sanderson, D C W; White, D C

    2006-02-01

    The uncertainties associated with airborne gamma spectrometry (AGS) measurements analysed using a spectral windows method, and associated detection limits, have been investigated. For individual short measurements over buried 137Cs activity detection limits of 10 kBq m(-2) are achieved. These detection limits are reduced for superficial activity and longer integration times. For superficial activity, detection limits below 1 kBq m(-2) are achievable. A comparison is made with the detection limits for other data processing methods.

  16. A Resolution Analysis of Two Geophysical Imaging Methods For Characterizing and Monitoring Hydrologic Conditions in the Vadose Zone

    SciTech Connect

    Alumbaugh, D.; LaBreque, D.; Brainard, J.; Hammond, G.

    2006-08-02

    The objective of this research project was to analyze the resolution of two geophysical imaging techniques: electrical resistivity tomography (ERT) and cross-borehole ground penetrating radar (XBGPR) for monitoring subsurface flow and transport processes within the vadose zone. This was accomplished through a coupled approach involving very fine-scale unsaturated flow forward modeling, conversion of the resultant flow and solute fields to geophysical property models, forward geophysical modeling using the property model obtained from the last step to obtain synthetic geophysical data, and finally inversion of this synthetic data. These geophysical property models were then compared to those derived from the conversion of the hydrologic forward modeling to provide an understanding of the resolution and limitations of the geophysical techniques.

  17. Status of data, major results, and plans for geophysical activities, Yucca Mountain Project

    SciTech Connect

    Oliver, H.W.; Hardin, E.L.; Nelson, P.H.

    1990-07-01

    This report describes past and planned geophysical activities associated with the Yucca Mountain Project and is intended to serve as a starting point for integration of geophysical activities. This report relates past results to site characterization plans, as presented in the Yucca Mountain Site Characterization Plan (SCP). This report discusses seismic exploration, potential field methods, geoelectrical methods, teleseismic data collection and velocity structural modeling, and remote sensing. This report discusses surface-based, airborne, borehole, surface-to-borehole, crosshole, and Exploratory Shaft Facility-related activities. The data described in this paper, and the publications discussed, have been selected based on several considerations; location with respect to Yucca Mountain, whether the success or failure of geophysical data is important to future activities, elucidation of features of interest, and judgment as to the likelihood that the method will produce information that is important for site characterization. 65 refs., 19 figs., 12 tabs.

  18. Agricultural geophysics: Past/present accomplishments and future advancements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods have become an increasingly valuable tool for application within a variety of agroecosystems. Agricultural geophysics measurements are obtained at a wide range of scales and often exhibit significant variability both temporally and spatially. The three geophysical methods predomi...

  19. Comparative analysis of different retrieval methods for mapping grassland leaf area index using airborne imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Atzberger, Clement; Darvishzadeh, Roshanak; Immitzer, Markus; Schlerf, Martin; Skidmore, Andrew; le Maire, Guerric

    2015-12-01

    Fine scale maps of vegetation biophysical variables are useful status indicators for monitoring and managing national parks and endangered habitats. Here, we assess in a comparative way four different retrieval methods for estimating leaf area index (LAI) in grassland: two radiative transfer model (RTM) inversion methods (one based on look-up-tables (LUT) and one based on predictive equations) and two statistical modelling methods (one partly, the other entirely based on in situ data). For prediction, spectral data were used that had been acquired over Majella National Park in Italy by the airborne hyperspectral HyMap instrument. To assess the performance of the four investigated models, the normalized root mean squared error (nRMSE) and coefficient of determination (R2) between estimates and in situ LAI measurements are reported (n = 41). Using a jackknife approach, we also quantified the accuracy and robustness of empirical models as a function of the size of the available calibration data set. The results of the study demonstrate that the LUT-based RTM inversion yields higher accuracies for LAI estimation (R2 = 0.91, nRMSE = 0.18) as compared to RTM inversions based on predictive equations (R2 = 0.79, nRMSE = 0.38). The two statistical methods yield accuracies similar to the LUT method. However, as expected, the accuracy and robustness of the statistical models decrease when the size of the calibration database is reduced to fewer samples. The results of this study are of interest for the remote sensing community developing improved inversion schemes for spaceborne hyperspectral sensors applicable to different vegetation types. The examples provided in this paper may also serve as illustrations for the drawbacks and advantages of physical and empirical models.

  20. Using Methods of Dimension Reduction to Expand Data Integration and Reduce Uncertainty in Hydrological and Geophysical Parameters

    NASA Astrophysics Data System (ADS)

    Yu, A.; Savoy, H.; Heße, F.; Rubin, Y.

    2015-12-01

    The Method of Anchored Distributions (MAD), first demonstrated by Rubin et al. in 2010, has been particularly useful in hydrological and geophysical applications. MAD provides a new framework for successfully using diverse data for the characterization of heterogeneous subsurface quantities (eg. hydraulic conductivity). Through Bayesian inverse modeling, MAD is able to take a general, assumption-free approach, incorporating both local data, ie. data that pertains directly to the target quantity, as well as other indirectly related non-local data. The latter are used for the inversion and converted into local data, called 'anchors', therefore improving the overall characterization of the target variable. However, with the use of more and more data, problems arise with the inversion due to the high dimensionality of said data, eg. when using time series. As a result, MAD becomes increasingly difficult, if not impossible, to use for large data sets. The objective of our study is therefore to investigate and demonstrate effective methods of dimension reduction that reduces large data sets to a small set of relevant parameters while still retaining a strong effect on the inversion procedure. The poster will explain the relevant methods and present examples of their effect on different data types, primarily looking at hydrological data (ie. concentration breakthrough curves, drawdown time series or vertical head profiles) then further theorizing its possible application to geophysical information. Ultimately, the broader goal of this study is to propose ways of applying dimension reduction to the realm of hydrogeophysics, which will not only expand the application of MAD, but also improve our ability to reduce uncertainty in the relevant parameters.

  1. A miniature research vessel: A small-scale ocean-exploration demonstration of geophysical methods

    NASA Astrophysics Data System (ADS)

    Howell, S. M.; Boston, B.; Sleeper, J. D.; Cameron, M. E.; Togia, H.; Anderson, A.; Sigurdardottir, T. D.; Tree, J. P.

    2015-12-01

    Graduate student members of the University of Hawaii Geophysical Society have designed a small-scale model research vessel (R/V) that uses sonar to create 3D maps of a model seafloor in real-time. A pilot project was presented to the public at the School of Ocean and Earth Science and Technology's (SOEST) Biennial Open House weekend in 2013 and, with financial support from the Society of Exploration Geophysicists and National Science Foundation, was developed into a full exhibit for the same event in 2015. Nearly 8,000 people attended the two-day event, including children and teachers from Hawaii's schools, home school students, community groups, families, and science enthusiasts. Our exhibit demonstrates real-time sonar mapping of a cardboard volcano using a toy size research vessel on a programmable 2-dimensional model ship track suspended above a model seafloor. Ship waypoints were wirelessly sent from a Windows Surface tablet to a large-touchscreen PC that controlled the exhibit. Sound wave travel times were recorded using an ultrasonic emitter/receiver attached to an Arduino microcontroller platform and streamed through a USB connection to the control PC running MatLab, where a 3D model was updated as the ship collected data. Our exhibit demonstrates the practical use of complicated concepts, like wave physics, survey design, and data processing in a way that the youngest elementary students are able to understand. It provides an accessible avenue to learn about sonar mapping, and could easily be adapted to talk about bat and marine mammal echolocation by replacing the model ship and volcano. The exhibit received an overwhelmingly positive response from attendees and incited discussions that covered a broad range of earth science topics.

  2. Airborne Linear Array Image Geometric Rectification Method Based on Unequal Segmentation

    NASA Astrophysics Data System (ADS)

    Li, J. M.; Li, C. R.; Zhou, M.; Hu, J.; Yang, C. M.

    2016-06-01

    As the linear array sensor such as multispectral and hyperspectral sensor has great potential in disaster monitoring and geological survey, the quality of the image geometric rectification should be guaranteed. Different from the geometric rectification of airborne planar array images or multi linear array images, exterior orientation elements need to be determined for each scan line of single linear array images. Internal distortion persists after applying GPS/IMU data directly to geometrical rectification. Straight lines may be curving and jagged. Straight line feature -based geometrical rectification algorithm was applied to solve this problem, whereby the exterior orientation elements were fitted by piecewise polynomial and evaluated with the straight line feature as constraint. However, atmospheric turbulence during the flight is unstable, equal piecewise can hardly provide good fitting, resulting in limited precision improvement of geometric rectification or, in a worse case, the iteration cannot converge. To solve this problem, drawing on dynamic programming ideas, unequal segmentation of line feature-based geometric rectification method is developed. The angle elements fitting error is minimized to determine the optimum boundary. Then the exterior orientation elements of each segment are fitted and evaluated with the straight line feature as constraint. The result indicates that the algorithm is effective in improving the precision of geometric rectification.

  3. Method for collecting naturally occurring airborne bacterial spores for determining their thermal resistance.

    PubMed

    Puleo, J R; Favero, M S; Oxborrow, G S; Herring, C M

    1975-11-01

    The ability to determine the thermal resistance of naturally occurring airborne bacterial spores associated with spacecraft and their assembly areas has been hindered by lack of an effective collecting system. Efforts to collect and concentrate spores with air samplers or from air filters have not been successful. A fallout method was developed for this purpose and tested. Sterile Teflon ribbons (7.6 by 183 cm) were exposed in pertinent spacecraft assembly areas and subsequently treated with dry heat. Thermal inactivation experiments were conducted at 125 and 113 C. Heating intervals ranged from 1 to 12 h at 125 C and 6, 12, 18, and 24 h at 113 C. Eight hours was the longest heating time yielding survivors at 125 C, whereas survivors were recovered at all of the heating intervals at 113 C. D125C values were calculated using the fractional-replicate-unit-negative technique of Pflug and Schmidt (1968) and ranged from 25 to 126 min. This variation indicated that the most probable number of survivors at each heating interval did not fall on a straight line passing through the initial spore population. However, the most-probable-number values taken alone formed a straight line suggesting logarithmic thermal destruction of a subpopulation of spores with a D125C value of 6.3 h.

  4. Detection of conduit-controlled ground-water flow in northwestern Puerto Rico using aerial photograph interpretation and geophysical methods

    USGS Publications Warehouse

    Rodríguez-Martínez, Jesús; Richards, Ronald T.

    2000-01-01

    The development potential of ground-water resources in the karst limestone of northwestern Puerto Rico, in an area extending from the Río Camuy to Aguadilla, is uncertain as a result of limited knowledge of the location of areas where a high density of cavities (interconnected fractures, conduits, and other dissolution features) might suggest the occurrence of high water yields. The presence in northwestern Puerto Rico of numerous coastal submarine springs, cavernous porosity in some of the wells, and rivers with entrenched and underground paths, indicate that it is probable that water-bearing, subterranean interconnected cavities occur in the area between the Río Camuy and Aguadilla. The number of exploratory wells needed to determine the location of these conduits or zones of enhanced secondary porosity could be substantially reduced if more information were available about the location of these subterranean features, greatly reducing the drilling costs associated with a trial-and-error exploratory process. A 3-year study was conducted by the U.S. Geological Survey, in cooperation with the Puerto Rico Aqueduct and Sewer Authority, to detect the presence of cavities that might suggest the occurrence of conduit-controlled groundwater flow. Aerial photographs, geologic and topographic maps, and field reconnaissance were used to identify such linear terrain features as ridges, entrenched canyons, and fracture traces. Natural potential and gravity geophysical methods were also used. The following sites were selected for the aerial photograph interpretation and geophysical testing: Caimital Bajo uplands and former Ramey Air Force Base in Aguadilla; Quebrada de los Cedros between Aguadilla and Isabela; the University of Puerto Rico Agricultural Experiment Station, Otilio dairy farm, and Pozo Brujo in Isabela; the Monte Encantado area in Moca and Isabela; and the Rio Camuy cave system in Hatillo and Camuy. In general, the degree of success varied with site and the

  5. A pilot study of the dependence of radon concentration on the tectonic structures, using simple geophysical methods.

    PubMed

    Thinova, L; Fronka, A; Rovenska, K

    2011-05-01

    It is well known that there are great variations in radon concentrations in the soil gas on building sites. The concentration may sometimes vary by more than two orders of magnitude. The tectonic structure of the bedrock is one of the factors that influence the intensity of the radon outflow. The simple ARES geophysical method [automatic resistivity system--main unit with standard accessories, multi-electrode cable sections (MCS5)--eight electrodes per 5 m spacing] was used in various modes (Schlumberger, Dipole-Dipole and Pole-Dipole arrays) for in situ tectonic structure determination. The radon concentration in the soil gas was measured using the same network as for the resistivity measurements. The radon measurements were also followed up by in situ gamma spectrometry measurements. The behaviour of the radon concentration in the soil gas was correlated with the detected tectonic non-homogeneities. This pilot study opened up new questions for future analysis.

  6. Geophysical Sounding

    NASA Astrophysics Data System (ADS)

    Blake, E.

    1998-01-01

    Of the many geophysical remote-sensing techniques available today, a few are suitable for the water ice-rich, layered material expected at the north martian ice cap. Radio echo sounding has been used for several decades to determine ice thickness and internal structure. Selection of operating frequency is a tradeoff between signal attenuation (which typically increases with frequency and ice temperature) and resolution (which is proportional to wavelength). Antenna configuration and size will be additional considerations for a mission to Mars. Several configurations for ice-penetrating radar systems are discussed: these include orbiter-borne sounders, sounding antennas trailed by balloons and penetrators, and lander-borne systems. Lander-borne systems could include short-wave systems capable of resolving fine structure and layering in the upper meters beneath the lander. Spread-spectrum and deconvolution techniques can be used to increase the depth capability of a radar system. If soundings over several locations are available (e.g., with balloons, rovers, or panning short-wave systems), then it will be easier to resolve internal layering, variations in basal reflection coefficient (from which material properties may be inferred), and the geometry of nonhorizontal features. Sonic sounding has a long history in oil and gas exploration. It is, however, unlikely that large explosive charges, or even swept-frequency techniques such as Vibroseis, would be suitable for a Polar lander -- these systems are capable of penetrating several kilometers of material at frequencies of 10-200 Hz, but the energy required to generate the sound waves is large and potentially destructive. The use of audio-frequency and ultrasonic sound generated by piezoelectric crystals is discussed as a possible method to explore layering and fine features in the upper meters of the ice cap. Appropriate choice of transducer(s) will permit operation over a range of fixed or modulated frequencies

  7. A method to quantify infectious airborne pathogens at concentrations below the threshold of quantification by culture.

    PubMed

    Cutler, Timothy D; Wang, Chong; Hoff, Steven J; Zimmerman, Jeffrey J

    2013-04-01

    In aerobiology, dose-response studies are used to estimate the risk of infection to a susceptible host presented by exposure to a specific dose of an airborne pathogen. In the research setting, host- and pathogen-specific factors that affect the dose-response continuum can be accounted for by experimental design, but the requirement to precisely determine the dose of infectious pathogen to which the host was exposed is often challenging. By definition, quantification of viable airborne pathogens is based on the culture of micro-organisms, but some airborne pathogens are transmissible at concentrations below the threshold of quantification by culture. In this paper we present an approach to the calculation of exposure dose at microbiologically unquantifiable levels using an application of the "continuous-stirred tank reactor (CSTR) model" and the validation of this approach using rhodamine B dye as a surrogate for aerosolized microbial pathogens in a dynamic aerosol toroid (DAT).

  8. A comprehensive uncertainty analysis and method of geometric calibration for a circular scanning airborne lidar

    NASA Astrophysics Data System (ADS)

    Gonsalves, Michael Oliver

    This dissertation describes an automated technique for ascertaining the values of the geometric calibration parameters of an airborne lidar. A least squares approach is employed that adjusts the point cloud to a single planar surface which could be either a narrow airport runway or a dynamic sea surface. Going beyond the customary three boresight angles, the proposed adjustment can determine up to eleven calibration parameters to a precision that renders a negligible contribution to the point cloud's positional uncertainty. Presently under development is the Coastal Zone Mapping and Imaging Lidar (CZMIL), which, unlike most contemporary systems that use oscillating mirrors to reflect the beam, will use a circular spinning prism to refract the laser in the desired direction. This departure from the traditional scanner presents the potential for internal geometric misalignments not previously experienced. Rather than relying on past calibration practices (like requiring data be acquired over a pitched-roof), a more robust method of calibration is established which does not depend on the presence of any cultural features. To develop this new method of calibration, the laser point positioning equation for this lidar was developed first. The system was then simulated in the MATLAB environment. Using these artificial datasets, the behavior of each geometric parameter iii was systematically manipulated, understood and calibrated, while an optimal flight strategy for the calibration acquisition was simultaneously developed. Finally, the total propagated uncertainty (TPU) of the point cloud was determined using a propagation of variances. Using this TPU module, the strength of the calibration solution was assessed. For example, four flight lines each of 20 seconds in duration contained sufficient information to determine the calibration parameters to such a degree of confidence that their contribution to the final point cloud uncertainty was only 0.012m in the horizontal

  9. An automated method to register airborne and terrestrial laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Yang, Bisheng; Zang, Yufu; Dong, Zhen; Huang, Ronggang

    2015-11-01

    Laser scanning techniques have been widely used to capture three-dimensional (3D) point clouds of various scenes (e.g. urban scenes). In particular, airborne laser scanning (ALS) and mobile laser scanning (MLS), terrestrial laser scanning (TLS) are effective to capture point clouds from top or side view. Registering the complimentary point clouds captured by ALS and MLS/TLS provides an aligned data source for many purposes (e.g. 3D reconstruction). Among these MLS can be directly geo-referenced to ALS according to the equipped position systems. For small scanning areas or dense building areas, TLS is used instead of MLS. However, registering ALS and TLS datasets suffers from poor automation and robustness because of few overlapping areas and sparse corresponding geometric features. A robust method for the registration of TLS and ALS datasets is proposed, which has four key steps. (1) extracts building outlines from TLS and ALS data sets independently; (2) obtains the potential matching pairs of outlines according to the geometric constraints between building outlines; (3) constructs the Laplacian matrices of the extracted building outlines to model the topology between the geometric features; (4) calculates the correlation coefficients of the extracted geometric features by decomposing the Laplacian matrices into the spectral space, providing correspondences between the extracted features for coarse registration. Finally, the multi-line adjustment strategy is employed for the fine registration. The robustness and accuracy of the proposed method are verified using field data, demonstrating a reliable and stable solution to accurately register ALS and TLS datasets.

  10. Case studies of geophysical search methods relevant to the continuation phase of an on-Site inspection

    SciTech Connect

    Sweeney, J J

    1999-04-20

    Part II of the Protocol of the Comprehensive Test Ban Treaty prescribes the use of geophysical methods such as active seismic surveys and electrical conductivity measurements to search for and locate underground anomalies, including cavities and rubble zones, during the continuation phase of an on-site inspection. In this paper the application of spontaneous potential, magnetotelluric, active seismic, and gas sampling studies at the US Nevada Test Site associated with underground nuclear explosions will be described and discussed in the context of on-site inspections. Spontaneous potential and E-field ratio telluric methods were found to be effective in some geologic settings but not in others. An example of gas sampling is shown for which radiogenic gas was detected several years after detonation. The case study of the application of active seismic methods illustrates limitations imposed by the use of relatively simple systems in the field. Detection of a deeply-buried cavity or rubble zone will be difficult; results from the application of only a single method will likely be ambiguous. Best results will come from the synthesis of results from a number of widely-varying methods.

  11. Aerial remote sensing surveys, geophysical characterization. Final report

    SciTech Connect

    Labson, V.F.; Pellerin, L.; Anderson, W.L.

    1998-06-01

    The application of helicopter electromagnetic (HEM) and magnetic methods to the requirements of the environmental restoration of the Oak Ridge Reservation (ORR) demand the use of advanced, nontraditional methods of data acquisition, processing and interpretation. The cooperative study by the U.S. Geological Survey (USGS), Oak Ridge National Laboratory (ORNL), and University of California (UCB) has resulted in the planning and supervision of data acquisition, the development of tools for data processing and interpretation, and an intensive application of the methods developed. This final report consists of a series of publications which the USGS collaborated with the ORNL technical staff. These reports represent the full scope of the USGS assistance. Copies of the reports and papers are included in the Appendix. The primary goals of this effort were to quantify the effectiveness of the geophysical methods applied in the survey of the ORR for the identification of buried waste, hydrogeologic pathways by which contamination could migrate through or off the site, and for the more accurate geologic mapping of the ORR. The objectives in buried waste identification are the accurate description of the source of the geophysical anomaly and the determination of the limits of resolution of the geophysical methods to acknowledge what we might have missed. The study of hydrogeologic pathways concentrated on the identification of karst features in the limestone underlying much of the ORR. Work in this study has indicated to the ORNL staff that these karst features can be located from the airborne geophysics. The defining characteristic of this helicopter geophysical study is the collaborative nature of the effort. Each task in which the USGS was involved has included a designated staff member from the Oak Ridge National Laboratory.

  12. Hydrogeologic Characterization of Fractured Crystalline Bedrock on the Southern Part of Manhattan, New York, Using Advanced Borehole Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Stumm, F.; Chu, A.; Joesten, P. K.; Lane, J. W.

    2007-12-01

    ABSTRACT. Advanced borehole-geophysical methods were used to assess the hydrogeology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, N.Y. The majority of boreholes penetrated gneiss, schist, and other crystalline bedrock, and had an average depth of 591 ft (180 m) below land surface (BLS). In this study we use a combination of advanced and conventional borehole geophysical logs, and hydraulic measurements to characterize the fractured-rock ground-water flow system in southern Manhattan, N.Y. Borehole-geophysical logs collected in this study included natural gamma, single-point-resistance (SPR), short-normal resistivity (R), mechanical and acoustic caliper, magnetic susceptibility, borehole-fluid temperature and resistivity, specific conductance (SpC), dissolved oxygen (DO), pH, redox, heat-pulse flowmeter (at eight selected boreholes), borehole deviation, acoustic and optical televiewer (ATV and OTV), and directional borehole radar (at 23 selected boreholes). A new geophysical probe that collects multiple fluid parameters, included fluid- temperature, SpC, DO, pH, and redox logs; these were used to help delineate transmissive fractures in the boreholes. All boreholes penetrated moderately fractured bedrock that contained medium and large fractures. A total of 208 large fractures were delineated in the 31 boreholes logged with the OTV. Stereonet analysis of the large fractures indicates most are part of a subhorizontal population cluster with a mean orientation of N43 degrees E, 07 degrees SE and a smaller secondary population cluster dipping toward the northwest. A total of 53 faults were delineated with two major population clusters--one with a mean orientation of N12 degrees W, 66 degrees W and the other with a mean orientation of N11 degrees W, 70 degrees E. Foliation was fairly consistent throughout the study area with dip azimuths ranging from northwest to southwest and dip angles ranging from 30 to 70 degrees

  13. A resolution analysis of two geophysical imaging methods for characterizing and monitoring hydrologic conditions in the Vadose zone.

    SciTech Connect

    Brainard, James Robert; Hammond, Gary.; Alumbaugh, David L.; La Brecque, D.J.

    2007-06-01

    This research project analyzed the resolution of two geophysical imaging techniques, electrical resistivity tomography (ERT) and cross-borehole ground penetrating radar (XBGPR), for monitoring subsurface flow and transport processes within the vadose zone. The study was based on petrophysical conversion of moisture contents and solute distributions obtained from unsaturated flow forward modeling. This modeling incorporated boundary conditions from a potable water and a salt tracer infiltration experiment performed at the Sandia-Tech Vadose Zone (STVZ) facility, and high-resolution spatial grids (6.25-cm spacing over a 1700-m domain) and incorporated hydraulic properties measured on samples collected from the STVZ. The analysis process involved petrophysical conversion of moisture content and solute concentration fields to geophysical property fields, forward geophysical modeling using the geophysical property fields to obtain synthetic geophysical data, and finally, inversion of this synthetic data. These geophysical property models were then compared to those derived from the conversion of the hydrologic forward modeling to provide an understanding of the resolution and limitations of the geophysical techniques.

  14. Comparison of different detection methods for citrus greening disease based on airborne multispectral and hyperspectral imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus greening or Huanglongbing (HLB) is a devastating disease spread in many citrus groves since first found in 2005 in Florida. Multispectral (MS) and hyperspectral (HS) airborne images of citrus groves in Florida were taken to detect citrus greening infected trees in 2007 and 2010. Ground truthi...

  15. Constraining the Hydrogeology of Marine Gas Hydrate Areas in the Gulf of Mexico Using High-Resolution Geophysical Methods

    NASA Astrophysics Data System (ADS)

    Ruppel, C.; Brooks, J.; O'Brien, T.; Lizarralde, D.; Nimblett, J.

    2002-12-01

    Previous work in our group has demonstrated that fluid (water + aqueous phase gas), gas, and energy fluxes largely control the dynamics of marine gas hydrate provinces. In the Gulf of Mexico, stratigraphic and structural complexities impart a high degree of spatial and temporal variability to these flux regimes and to the resulting concentration and distribution of gas hydrates. While this complexity poses a challenge to understanding the hydrogeology of gas hydrate zones in the Gulf, the juxtaposition of low and high flux regions and of diffuse and focused flux zones provides an important opportunity to study a range of hydrate-related environments at a compressed spatial scale. An additional advantage in this setting is related to elevated thermal gradients and high advective transport rates, which lead to the formation and long-term stability of gas hydrate at the seafloor or in the uppermost meters of sediment in some locations. Gulf of Mexico gas hydrates are therefore sometimes highly accessible to geophysical methods that yield information about the shallowest part of the sedimentary column. In this study, we apply high-resolution geophysical methods to image fluid conduits, describe the thermal state of the gas hydrate reservoir, constrain advective fluid flux rates, and map lateral variability in flow regimes in 3 regions targeted for possible future gas hydrates drilling in the Gulf of Mexico: Mississippi Canyon, Bush Hill (GC 185), and Garden Banks 425. Using limited Chirp seismic data, we determine the location of stratigraphic and structural features that focus fluid flow or trap fluids and gas, processes that both contribute to increased concentrations of gas hydrate under many circumstances. In a relatively novel application of traditional marine heat flow methods, we also report the results of high-resolution surveys that exploit the inherent accuracy of the instrumentation to map lateral changes in thermal regimes on multiple spatial scales as one

  16. Manifold methods for assimilating geophysical and meteorological data in Earth system models and their components

    NASA Astrophysics Data System (ADS)

    Safaie, Ammar; Dang, Chinh; Qiu, Han; Radha, Hayder; Phanikumar, Mantha S.

    2017-01-01

    A novel manifold method of reconstructing dynamically evolving spatial fields is presented for assimilating data from sensor networks in integrated land surface - subsurface, oceanic/lake models. The method was developed based on the assumption that data can be mapped onto an underlying differential manifold. In this study, the proposed method was used to reconstruct meteorological forcing over Lake Michigan, the bathymetry of an inland lake (Gull Lake), and precipitation over the Grand River watershed in Michigan. In the first case study, hourly meteorological forcing data were reconstructed and used to run a three-dimensional hydrodynamic model of Lake Michigan and to quantify the improvement that results from the use of the new method. In the second example, the bathymetry of Gull Lake was reconstructed from measured scatter point data using the manifold technique. A hydrodynamic model of Gull Lake was developed and refined using the improved bathymetry. In the last case study, improved daily participation data for a six-year period over the Grand River watershed were used as input to an integrated, distributed hydrologic model. All three examples illustrate the superior performance of the manifold method over standard methods in terms of accuracy and computational efficiency. Our results also indicate that using the cross-validation technique to evaluate the performance of data reconstruction methods can lead to misleading conclusions about their relative performance.

  17. ON THE PHYSICS OF GALVANIC SOURCE ELECTROMAGNETIC GEOPHYSICAL METHODS FOR TERRESTRIAL AND MARINE EXPLORATION

    SciTech Connect

    David Alumbaugh and Evan Um

    2007-06-27

    A numerical study was conducted to investigate the governing physics of galvanic source electromagnetic (EM) methods for terrestrial and marine exploration scenarios. The terrestrial exploration scenario involves the grounded electric dipole source EM (GESTEM) method and the examination of how the GESTEM method can resolve a thin resistive layer representing underground gas and/or hydrocarbon storage. Numerical modeling studies demonstrate that the loop transient EM (TEM) and magnetotelluric (MT) methods are insensitive to a thin horizontal resistor at depth because they utilize horizontal currents. In contrast to these standard EM methods, the GESTEM method generates both vertical and horizontal transient currents. The vertical transient current interacts with a thin horizontal resistor and causes charge buildup on its surface. These charges produce a measurable perturbation in the surface electric field at early time. The degree of perturbation depends on source waveform. When the GESTEM method is energized with step-off waveform, the perturbation due to a thin horizontal resistor is small. This is because the step-off waveform mainly consists of low frequency signals. An alternative is taking the time-derivative of the step-off responses to approximate the impulse response which includes higher frequency signals. In order to improve degree of perturbation especially due to a localized small 3-D resistor, the diffusion angle of the vertical transient current, 45 should be considered to make vertical currents coupled to a resistive target efficiently. The major drawback of the GESTEM method lies in the fact that GESTEM sounding can not be interpreted using 1-D inversion schemes if there is near-surface inhomogeneity. The marine exploration scenario investigates the physics of marine frequency-domain controlled source EM (FDCSEM) and time-domain controlled source EM (TDCSEM) methods to explore resistive hydrocarbon reservoirs in marine environments. Unlike the

  18. Capacitance sounding: a new geophysical method for asphalt pavement quality evaluation

    NASA Astrophysics Data System (ADS)

    Dashevsky, Yu. A.; Dashevsky, O. Yu.; Filkovsky, M. I.; Synakh, V. S.

    2005-02-01

    A capacitance sounding method has been proposed and developed for evaluation of the actual thickness and dielectric permittivity of asphalt pavement. The method is based on the continuous measurements of the electrical capacitance between two electrodes in real time. One of them is grounded within the soil immediately adjacent to the side of the road. Another one (sensing electrode) is mounted on a motor-driven positioner to obtain the capacitance measurements at multiple locations along the direction perpendicular to asphalt surface. The principle of the method is to vary the clearance of the sensing electrode to sound the 1D structure of the pavement beneath that electrode. A distinguished feature of the proposed technology is that the measured signal depends only on the thickness and the permittivity of the asphalt layer. All underlying layers do not affect the capacitance readings. A set of capacitance values versus sensing electrode positions is considered as a sounding curve. Software tools were created for solving forward and inverse problems of the capacitance sounding. An unknown thickness and permittivity are derived from a real-time inversion of the data obtained. Upon completing the inversion, an operator can move the assembling with the second electrode across the asphalt surface to the next sounding site. The capacitance sounding method proved to have a good lateral resolution: the dielectric permittivity values and the asphalt layer thickness are accurately detected over distances of 40 cm from a measuring point. An extensive feasibility study of capacitance sounding using both mathematical modeling and field measurements has been carried out. As a result, portable, low-frequency equipment has been designed and created. Asphalt layer thickness and the dielectric permittivity measurements were carried out on a high-traffic highway. The comparison of field trial results with core sampling analysis demonstrated the efficiency of the proposed method.

  19. Geltape method for measurement of work related surface contamination with cobalt containing dust: correlation between surface contamination and airborne exposure.

    PubMed Central

    Poulsen, O M; Olsen, E; Christensen, J M; Vinzent, P; Petersen, O H

    1995-01-01

    OBJECTIVES--The geltape method is a new method for optical measurement of total amount of dust on surfaces. The objectives were to study the potential applicability of this method to measurements of work related cobalt exposure during painting of plates with cobalt dye. METHODS--Consecutive series of work related geltape prints were taken from surfaces inside and outside the ventilation cabins of two plate painters during two full working days. The amount of dust picked up by the geltapes was measured optically with a field monitor. Also, personal air samples were collected on filters at the different work processes. In the laboratory the contents of cobalt on the geltape prints and the filters were measured with inductive coupled plasma atomic emission spectroscopy. RESULTS--The key results were: (a) when the geltape prints were taken from surfaces inside the cabins the optically measured area of the geltapes covered with total dust (area (%)) correlated well with the chemically measured amount of cobalt present on the geltapes. Linear correlation coefficient (R2) was 0.91 for geltape prints taken on the floor and 0.94 for prints taken on the ceiling; (b) the cumulative airborne cobalt exposure, calculated from data on work related exposure by personal sampling, correlated with the area (%) of geltape prints taken from the ceiling of the cabin (R2 = 0.98); (c) the geltape method could be used to distinguish both between work processes with different levels of cobalt exposure, and between plate painters subjected to significant differences in airborne cobalt exposure. CONCLUSION--The geltape method could produce measures of the work related exposures as well as whole day exposure for cobalt. The geltape results correlated with measurements of personal airborne cobalt exposure. In this industry the profile of exposure is well-defined in time, and it seems reasonable to apply this fast and low cost method in routine exposure surveillance to obtain a more detailed

  20. Airborne gravity is here

    SciTech Connect

    Hammer, S.

    1982-01-11

    After 20 years of development efforts, the airborne gravity survey has finally become a practical exploration method. Besides gravity data, the airborne survey can also collect simultaneous, continuous records of high-precision magneticfield data as well as terrain clearance; these provide a topographic contour map useful in calculating terrain conditions and in subsequent planning and engineering. Compared with a seismic survey, the airborne gravity method can cover the same area much more quickly and cheaply; a seismograph could then detail the interesting spots.

  1. Application of spectral Lanczos decomposition method to large scale problems arising geophysics

    SciTech Connect

    Tamarchenko, T.

    1996-12-31

    This paper presents an application of Spectral Lanczos Decomposition Method (SLDM) to numerical modeling of electromagnetic diffusion and elastic waves propagation in inhomogeneous media. SLDM approximates an action of a matrix function as a linear combination of basis vectors in Krylov subspace. I applied the method to model electromagnetic fields in three-dimensions and elastic waves in two dimensions. The finite-difference approximation of the spatial part of differential operator reduces the initial boundary-value problem to a system of ordinary differential equations with respect to time. The solution to this system requires calculating exponential and sine/cosine functions of the stiffness matrices. Large scale numerical examples are in a good agreement with the theoretical error bounds and stability estimates given by Druskin, Knizhnerman, 1987.

  2. Study on the Integrated Geophysic Methods and Application of Advanced Geological Detection for Complicated Tunnel

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Xiao, G.

    2014-12-01

    The engineering geological and hydrological conditions of current tunnels are more and more complicated, as the tunnels are elongated with deeper depth. In constructing these complicated tunnels, geological hazards prone to occur as induced by unfavorable geological bodies, such as fault zones, karst or hydrous structures, etc. The working emphasis and difficulty of the advanced geological exploration for complicated tunnels are mainly focused on the structure and water content of these unfavorable geological bodies. The technical aspects of my paper systematically studied the advanced geological exploration theory and application aspects for complicated tunnels, with discussion on the key technical points and useful conclusions. For the all-aroundness and accuracy of advanced geological exploration results, the objective of my paper is targeted on the comprehensive examination on the structure and hydrous characteristic of the unfavorable geological bodies in complicated tunnels. By the multi-component seismic modeling on a more real model containing the air medium, the wave field response characteristics of unfavorable geological bodies can be analyzed, thus providing theoretical foundation for the observation system layout, signal processing and interpretation of seismic methods. Based on the tomographic imaging theory of seismic and electromagnetic method, 2D integrated seismic and electromagnetic tomographic imaging and visualization software was designed and applied in the advanced drilling hole in the tunnel face, after validation of the forward and inverse modeling results on theoretical models. The transmission wave imaging technology introduced in my paper can be served as a new criterion for detection of unfavorable geological bodies. After careful study on the basic theory, data processing and interpretation, practical applications of TSP and ground penetrating radar (GPR) method, as well as serious examination on their application examples, my paper

  3. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, C.V.; Killian, E.W.; Grafwallner, E.G.; Kynaston, R.L.; Johnson, L.O.; Randolph, P.D.

    1996-09-03

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector. 7 figs.

  4. Device and method for accurately measuring concentrations of airborne transuranic isotopes

    DOEpatents

    McIsaac, Charles V.; Killian, E. Wayne; Grafwallner, Ervin G.; Kynaston, Ronnie L.; Johnson, Larry O.; Randolph, Peter D.

    1996-01-01

    An alpha continuous air monitor (CAM) with two silicon alpha detectors and three sample collection filters is described. This alpha CAM design provides continuous sampling and also measures the cumulative transuranic (TRU), i.e., plutonium and americium, activity on the filter, and thus provides a more accurate measurement of airborne TRU concentrations than can be accomplished using a single fixed sample collection filter and a single silicon alpha detector.

  5. Geophysical methods as mapping tools in a strata-bound gold deposit: Haile mine, South Carolina slate belt.

    USGS Publications Warehouse

    Wynn, J.C.; Luce, R.W.

    1984-01-01

    The Haile mine is the largest gold producer in the eastern USA. It is postulated to be a strata-bound gold deposit formed by a fumarolic or hot-spring system in felsic tuffs of Cambrian(?) age. Two mineralized zones occur, each composed of a sericitic part overlain by a siliceous part. Au is concentrated in especially silicified horizons and in pyrite horizons in the siliceous part of each mineralized zone. The tuffs are metamorphosed to greenschist facies and intruded by diabase and other mafic dykes. Weathering is deep and the mineralized tuffs are partly covered by coastal-plain sediments. It is suggested that certain geophysical methods may be useful in mapping and exploring Haile-type deposits in the Carolina slate belt. Very low frequency electromagnetic resistivity surveys help define alteration and silicified zones. A magnetic survey found sharp highs that correlate with unexposed mafic and ultramafic dykes. Induced polarization proved useful in giving a two-dimensional view of the structure.-G.J.N.

  6. An Experiment to Test Geophysical Methods For Monitoring Fluid Re-Injection at the Wairakei Geothermal Field, New Zealand

    NASA Astrophysics Data System (ADS)

    Jiracek, G. R.; Bowles-Martinez, E.; Feucht, D. W.; Ryan, J.; Caldwell, T. G.; Bannister, S. C.; Bertrand, T.; Bennie, S.; Bourguignon, S.

    2010-12-01

    The National Science Foundation (NSF) is supporting US students to participate in GNS Science’s geothermal research program supported by the New Zealand Government. The NSF international program aims to quick-start a new generation of geothermal-oriented US geophysics students who will be poised to be active participants and leaders in US geothermal energy development. This year’s project evaluated joint passive seismic and magnetotelluric (MT) field measurements to determine three-dimensional (3-D) reservoir characteristics during fluid withdrawal and re-injection. A preliminary test of the ability to achieve repeatable MT data in high noise locations was carried out in the Wairakei geothermal field using a 14-site base-line MT survey and repeat occupations at four sites. Different data processing schemes identified MT frequency bands where impedance phase tensor data were most sensitive to known variables such as daily solar source variations, wind, and drilling operations. Other frequency bands were identified where good MT repeatability will allow further tests. A streamlined method was developed for visualizing 3-D earthquake focal mechanisms resulting from production changes in geothermal reservoirs. The computer program allows spatial sorting of seismic events and thus subsurface fracture identification.

  7. Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods

    USGS Publications Warehouse

    Muto, A.; Scambos, T.A.; Steffen, K.; Slater, A.G.; Clow, G.D.

    2011-01-01

    We use measured firn temperatures down to depths of 80 to 90 m at four locations in the interior of Dronning Maud Land, East Antarctica to derive surface temperature histories spanning the past few decades using two different inverse methods. We find that the mean surface temperatures near the ice divide (the highest-elevation ridge of East Antarctic Ice Sheet) have increased approximately 1 to 1.5 K within the past ???50 years, although the onset and rate of this warming vary by site. Histories at two locations, NUS07-5 (78.65S, 35.64E) and NUS07-7 (82.07S, 54.89E), suggest that the majority of this warming took place in the past one or two decades. Slight cooling to no change was indicated at one location, NUS08-5 (82.63S, 17.87E), off the divide near the Recovery Lakes region. In the most recent decade, inversion results indicate both cooler and warmer periods at different sites due to high interannual variability and relatively high resolution of the inverted surface temperature histories. The overall results of our analysis fit a pattern of recent climate trends emerging from several sources of the Antarctic temperature reconstructions: there is a contrast in surface temperature trends possibly related to altitude in this part of East Antarctica. Copyright 2011 by the American Geophysical Union.

  8. A comparison of four geophysical methods for determining the shear wave velocity of soils

    USGS Publications Warehouse

    Anderson, N.; Thitimakorn, T.; Ismail, A.; Hoffman, D.

    2007-01-01

    The Missouri Department of Transportation (MoDOT) routinely acquires seismic cone penetrometer (SCPT) shear wave velocity control as part of the routine investigation of soils within the Mississippi Embayment. In an effort to ensure their geotechnical investigations are as effective and efficient as possible, the SCPT tool and several available alternatives (crosshole [CH]; multichannel analysis of surface waves [MASW]; and refraction microtremor [ReMi]) were evaluated and compared on the basis of field data acquired at two test sites in southeast Missouri. These four methods were ranked in terms of accuracy, functionality, cost, other considerations, and overall utility. It is concluded that MASW data are generally more reliable than SCPT data, comparable to quality ReMi data, and only slightly less accurate than CH data. However, the other advantages of MASW generally make it a superior choice over the CH, SCPT, and ReMi methods for general soil classification purposes to depths of 30 m. MASW data are less expensive than CH data and SCPT data and can normally be acquired in areas inaccessible to drill and SCPT rigs. In contrast to the MASW tool, quality ReMi data can be acquired only in areas where there are interpretable levels of "passive" acoustic energy and only when the geophone array is aligned with the source(s) of such energy.

  9. Geophex airborne unmanned survey system

    SciTech Connect

    Won, I.J.; Taylor, D.W.A.

    1995-03-01

    The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This nonintrusive system will provide {open_quotes}stand-off{close_quotes} capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. This system permits two operators to rapidly conduct geophysical characterization of hazardous environmental sites. During a survey, the operators remain remote from, but within visual distance, of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak anomalies can be detected.

  10. Borehole geophysical methods for analyzing specific capacity of multiaquifer wells : ground-water hydraulics

    USGS Publications Warehouse

    Bennett, Gordon D.; Patten, Eugene P.

    1960-01-01

    Conventional well-logging techniques, combined with measurements of flow velocity in the borehole, can provide information on the discharge-drawdown characteriBtic8 of the several aquifers penetrated by a well. The information is most conveniently presented in a graph showing aquifer discharges as functions of the water level in the well at a particular time. To determine the discharge-drawdown characteristics, a well is pumped at a steady rate for a certain length of time. While the well is being pumped, measurements are made of drawdown and of the discharge rates of the individual aquifers within the well. Discharge rates and drawdowns ,are usually recorded as functions of time, and their values for any given time during the test are obtained by interpolation. The procedure is repeated for several different rates of total well discharge. The well may be allowed to recover after each step, or discharge may be changed from one rate to another, and changes in discharge and drawdown may be measured by extrapolation. The flow measurements within the well may be made by use of a subsurface flowmeter or by one of several techniques involving the injection of electrolytic or radioactive tracers. The method was tested on a well in Mercer County, Pa., and provided much useful information on aquifer yields, 'thieving,' and hydrostatic heads of the individual zones.

  11. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carolo methods: A Case Study at the South Oyster Bacterial Transport Site in Virginia

    SciTech Connect

    Chen, Jinsong; Hubbard, Susan; Rubin, Yoram; Murray, Chris; Roden, Eric; Majer, Ernest

    2003-11-18

    The spatial distribution of field-scale geochemical parameters, such as extractable Fe(II) and Fe(III), influences microbial processes and thus the efficacy of bioremediation. Because traditional characterization of those parameters is invasive and laborious, it is rarely performed sufficiently at the field-scale. Since both geochemical and geophysical parameters often correlate to some common physical properties (such as lithofacies), we investigated the utility of tomographic radar attenuation data for improving estimation of geochemical parameters using a Markov Chain Monte Carlo (MCMC) approach. The data used in this study included physical, geophysical, and geochemical measurements collected in and between several boreholes at the DOE South Oyster Bacterial Transport Site in Virginia. Results show that geophysical data, constrained by physical data, provided field-scale information about extractable Fe(II) and Fe(III) in a minimally invasive manner and with a resolution unparalleled by other geochemical characterization methods. This study presents our estimation framework for estimating Fe(II) and Fe(III), and its application to a specific site. Our hypothesis--that geochemical parameters and geophysical attributes can be linked through their mutual dependence on physical properties--should be applicable for estimating other geochemical parameters at other sites.

  12. A method of fast, sequential experimental design for linearized geophysical inverse problems

    NASA Astrophysics Data System (ADS)

    Coles, Darrell A.; Morgan, Frank Dale

    2009-07-01

    An algorithm for linear(ized) experimental design is developed for a determinant-based design objective function. This objective function is common in design theory and is used to design experiments that minimize the model entropy, a measure of posterior model uncertainty. Of primary significance in design problems is computational expediency. Several earlier papers have focused attention on posing design objective functions and opted to use global search methods for finding the critical points of these functions, but these algorithms are too slow to be practical. The proposed technique is distinguished primarily for its computational efficiency, which derives partly from a greedy optimization approach, termed sequential design. Computational efficiency is further enhanced through formulae for updating determinants and matrix inverses without need for direct calculation. The design approach is orders of magnitude faster than a genetic algorithm applied to the same design problem. However, greedy optimization often trades global optimality for increased computational speed; the ramifications of this tradeoff are discussed. The design methodology is demonstrated on a simple, single-borehole DC electrical resistivity problem. Designed surveys are compared with random and standard surveys, both with and without prior information. All surveys were compared with respect to a `relative quality' measure, the post-inversion model per cent rms error. The issue of design for inherently ill-posed inverse problems is considered and an approach for circumventing such problems is proposed. The design algorithm is also applied in an adaptive manner, with excellent results suggesting that smart, compact experiments can be designed in real time.

  13. A Novel Azimuth Super-Resolution Method by Synthesizing Azimuth Bandwidth of Multiple Tracks of Airborne Stripmap SAR Data.

    PubMed

    Wang, Yan; Li, Jingwen; Sun, Bing; Yang, Jian

    2016-06-13

    Azimuth resolution of airborne stripmap synthetic aperture radar (SAR) is restricted by the azimuth antenna size. Conventionally, a higher azimuth resolution should be achieved by employing alternate modes that steer the beam in azimuth to enlarge the synthetic antenna aperture. However, if a data set of a certain region, consisting of multiple tracks of airborne stripmap SAR data, is available, the azimuth resolution of specific small region of interest (ROI) can be conveniently improved by a novel azimuth super-resolution method as introduced by this paper. The proposed azimuth super-resolution method synthesize the azimuth bandwidth of the data selected from multiple discontinuous tracks and contributes to a magnifier-like function with which the ROI can be further zoomed in with a higher azimuth resolution than that of the original stripmap images. Detailed derivation of the azimuth super-resolution method, including the steps of two-dimensional dechirping, residual video phase (RVP) removal, data stitching and data correction, is provided. The restrictions of the proposed method are also discussed. Lastly, the presented approach is evaluated via both the single- and multi-target computer simulations.

  14. a Box-Counting Method to Characterize Degrees of Foliage Clumping Using Airborne and Simulated LIDAR Data

    NASA Astrophysics Data System (ADS)

    van Leeuwen, M.; van Aardt, J. A. N.; Kampe, T.; Krause, K.

    2015-04-01

    Monitoring forest productivity and health is key to sustainable ecosystem management and informed decision making. A key parameter used in monitoring forest resources is the leaf area index (LAI), which is defined as the one-sided leaf area per unit ground area and is used to describe the canopy radiation regime, among other forest biophysical dynamics. Traditional optics-based methods to estimate LAI rely on the measurement of canopy transmission and foliage clumping. Extending optical methods to LiDAR data has been challenging and studies have reported effective LAI assessments, with no further quantification of foliage clumping. This study investigates the use of the box-counting method to assess the fractal dimension of point cloud data for contrasting forest types and along a gradient of foliage dispersal. We demonstrate the box-counting method on simulated 'range-to-hit', as well as acquired airborne discrete LiDAR data. Coherent results obtained from the different test cases hint at the potential of the box-counting fractal dimension to characterize foliage clumping and bode well for the use of clumping assessments in support of airborne, wall-to-wall estimates of LAI.

  15. A Novel Azimuth Super-Resolution Method by Synthesizing Azimuth Bandwidth of Multiple Tracks of Airborne Stripmap SAR Data

    PubMed Central

    Wang, Yan; Li, Jingwen; Sun, Bing; Yang, Jian

    2016-01-01

    Azimuth resolution of airborne stripmap synthetic aperture radar (SAR) is restricted by the azimuth antenna size. Conventionally, a higher azimuth resolution should be achieved by employing alternate modes that steer the beam in azimuth to enlarge the synthetic antenna aperture. However, if a data set of a certain region, consisting of multiple tracks of airborne stripmap SAR data, is available, the azimuth resolution of specific small region of interest (ROI) can be conveniently improved by a novel azimuth super-resolution method as introduced by this paper. The proposed azimuth super-resolution method synthesize the azimuth bandwidth of the data selected from multiple discontinuous tracks and contributes to a magnifier-like function with which the ROI can be further zoomed in with a higher azimuth resolution than that of the original stripmap images. Detailed derivation of the azimuth super-resolution method, including the steps of two-dimensional dechirping, residual video phase (RVP) removal, data stitching and data correction, is provided. The restrictions of the proposed method are also discussed. Lastly, the presented approach is evaluated via both the single- and multi-target computer simulations. PMID:27304959

  16. Investigation of the Sultan Alp Arslan tomb with geophysical methods, in the historical Merv city (Turkestan)

    NASA Astrophysics Data System (ADS)

    Kadioglu, Selma; Kagan Kadioglu, Yusuf

    2016-04-01

    Sultan Alp Arslan (1029-1072) was the second Sultan of the Seljuq Empire and great-grandson of Seljuq the eponymous founder of the dynasty. Sultan Alp Arslan's victories changed the balance in near Asia completely in favour of the Seljuq Turks and Sunni Muslims. His victory at Manzikert (26 August 1071) is often cited as the beginning of the end of Byzantine power in Anatolia, and the beginning of Turkish identity in Anatolia. Sultan Alp Arslan eliminated theobstacles to the conquest of Anatolia and played a major role in making this territory a homeland for the Seljuqs. By taking the Emperor captive, Sultan Alp Arslan gained great fame but in 1072, on an expedition to Western Turkestan, he met with death in an unexpected way and at a relatively early age, in his 42nd year. There have been found different stories of the death of this great Turkish Sultan in certain sources. Unfortunately, there has not been found The Sultan's resting place until now. This paper is concerned with the investigation of the Sultan Alp Arslan Tomb in the historical Merv (Marv) city in Turkestan, by using Ground Penetrating Radar (GPR) and gradiometer methods. The GPR and gradiometer surveys have been realized in Gavur Fortress, Sultan Fortress, Er Fortress districts and between two big Fortresses in old Merv city in selected nine study areas. We also gathered data in and around Sultan Sancar Tomb. GPR surveys were performed during January 2014 employing Ramac CU-II system equipped with a 250 MHz shielded antenna, on one meter spaced profiles. Similarly a Geoscan system was used to take magnetic data. The results of all these investigation revealed that there were possible traces for the buried tomb of the Sultan Alparslan in Gavur Kale around Cuma Mosque and around Sultan Sancar Tomb in the study region. However, the project team was changed after our study, and the new team did not excavated our determined areas. Acknowledgement This project has been supported by Republic of Turkey

  17. Review of airborne emissions from agricultural fumigants: design and uncertainty considerations for the use of the integrated horizontal flux method.

    PubMed

    Sullivan, D A; Ajwa, H A

    2011-01-01

    Ground-level area sources, such as those associated with the use of agricultural fumigants, waste disposal sites, wastewater lagoons, and other applications, present a challenge in terms of characterizing atmospheric flux as a function of time. Studies are costly in terms of field activities and laboratory analysis. The optimization of field study design, therefore, is essential to conduct cost-effective research. The collection of on-field profile data for airborne concentration, wind speed, and wind direction can be used in conjunction with the integrated horizontal flux (IHF) method to empirically compute complex source terms as a function of time. This paper focuses on complicating factors and field study design issues for the use of the IHF method. Insights and examples are drawn from five field research studies. The methods and results of characterizing the uncertainty and method precision in the emission fitting for the IHF method also are presented.

  18. Overview on geophysical monitoring at the Ketzin CO2 storage site (Germany) using seismic and geoelectric methods (Invited)

    NASA Astrophysics Data System (ADS)

    Bergmann, P.; Ivandic, M.; Ivanova, A.; Juhlin, C.; Lueth, S.; Schmidt-Hattenberger, C.

    2013-12-01

    At Ketzin, a town close to Berlin, the first European onshore pilot scale project was initiated in 2004. After baseline characterization and drilling, CO2 injection was commenced in June 2008. As of August 2013, ~67 kilotons have been injected. Using one injection well, the CO2 is injected in a super-critical state into sandstones of the Stuttgart Formation, a saline aquifer at 620 m to 650 m depth. The depth of the Ketzin reservoir and injected mass of CO2 are not representative for CCS activities at an industrial scale. However, due to the relatively small amount of CO2 injected, combined with a complex storage reservoir, the site poses qualified conditions for testing of monitoring approaches. Consequently, a wide range of geophysical methods are in operation at the Ketzin site. Asides from well logging, both seismic methods and electric resistivity tomography (ERT) are being extensively applied. The applied survey setups comprise surface measurements, borehole measurements, and combined surface-downhole measurements. So far, the most comprehensive view onto the CO2 migration in the Ketzin reservoir is provided by two repeat 3D seismic surveys acquired in 2009 and 2012. They revealed a time-lapse seismic signal from the reservoir which indicates that the CO2 has progressively expanded to distances of 400-600 m away from the injection well by 2012. The apparent westward component of the plume migration observed in the 2009 data, is confirmed by a more pronounced westward component in the 2012 data. Consistent with the seismic monitoring, an increase in electrical resistivity around the injector was mapped by means of repeated surface-downhole ERT which indicates the presence of the injected CO2. These ERT surveys consist of current injections at the surface and voltage registration at the storage reservoir by means of a permanent electrode array that is installed in three wells (injector plus two monitoring wells). The imaged resistivity increase is consistent

  19. The Hintereisferner - eight years of experience in method development for glacier monitoring with airborne LiDAR

    NASA Astrophysics Data System (ADS)

    Vetter, M.; Höfle, B.; Pfeifer, N.; Rutzinger, M.; Sailer, R.; Stötter, J.; Geist, T.

    2009-04-01

    Topographic data acquisition with LiDAR technology, airborne or terrestrial, has become the state-of-the-art procedure for Earth surface surveying. For glacier monitoring different remote sensing technologies are used for many years. With the advent of airborne LiDAR a paradigm shift in glacier monitoring has taken place. Eight years ago pioneer work within glacier surface surveying and monitoring has been carried out at the Institute of Geography (Innsbruck) within the OMEGA (Development of Operational Monitoring System for European Glacial Areas) project by using airborne LiDAR. Since 2001, 16 single airborne LiDAR campaigns have been carried out by collecting data of Hintereisferner, Kesselwandferner and adjacent small glaciers as well as their surrounding areas (Ötztal Alps, Tyrol, Austria). We present the main results of this period of glacier monitoring based on LiDAR data. One major task was to set up a geo-database system to manage the huge amount of LiDAR data, offering the opportunity to compute various point features and different rasterized data sets using this LiDAR data management and analysis system. In this context some basic routines were developed (e.g. a tool for intensity calibration, for derive intensity and point density images, and for modeling the locations of laser shot dropouts). In addition, tools for the analysis of the glacier surface have been developed: (a) a glacier delineation tool, using intensity and roughness information, (b) tools to compute and visualize the volume and elevation changes using multitemporal data, (c) a tool to calculate the ice flow velocity at the glacier surface, (d) a classification tool to detect crevasses, snow, firn, ice and debris covered ice areas, using calibrated intensity data, roughness information and modeled laser shot dropouts. For the analysis of glacial geomorphologic processes (i) a routine for the delineation of moraine ridges and rock glaciers works on the basis of break lines, (ii) a

  20. UAVSAR: An Airborne Window on Earth Surface Deformation

    NASA Technical Reports Server (NTRS)

    Hensley, Scott

    2011-01-01

    This study demonstrates that UAVSAR's precision autopilot and electronic steering have allowed for the reliable collection of airborne repeat pass radar interferometric data for deformation mapping. Deformation maps from temporal scales ranging from hours to months over a variety of signals of geophysical interest illustrate the utility of UAVSAR airborne repeat pass interferometry to these studies.

  1. Direct Analysis of Low-Volatile Molecular Marker Extract from Airborne Particulate Matter Using Sensitivity Correction Method

    PubMed Central

    Irei, Satoshi

    2016-01-01

    Molecular marker analysis of environmental samples often requires time consuming preseparation steps. Here, analysis of low-volatile nonpolar molecular markers (5-6 ring polycyclic aromatic hydrocarbons or PAHs, hopanoids, and n-alkanes) without the preseparation procedure is presented. Analysis of artificial sample extracts was directly conducted by gas chromatography-mass spectrometry (GC-MS). After every sample injection, a standard mixture was also analyzed to make a correction on the variation of instrumental sensitivity caused by the unfavorable matrix contained in the extract. The method was further validated for the PAHs using the NIST standard reference materials (SRMs) and then applied to airborne particulate matter samples. Tests with the SRMs showed that overall our methodology was validated with the uncertainty of ~30%. The measurement results of airborne particulate matter (PM) filter samples showed a strong correlation between the PAHs, implying the contributions from the same emission source. Analysis of size-segregated PM filter samples showed that their size distributions were found to be in the PM smaller than 0.4 μm aerodynamic diameter. The observations were consistent with our expectation of their possible sources. Thus, the method was found to be useful for molecular marker studies. PMID:27127511

  2. A new monitoring method using solid sorbent media for evaluation of airborne cyclophosphamide and other antineoplastic agents.

    PubMed

    Larson, Rodney R; Khazaeli, M B; Dillon, H Kenneth

    2003-02-01

    Cyclophosphamide is a known human carcinogen. In July 1999, in a report at a conference on cytotoxic drugs in Sweden, it was indicated that cyclophosphamide (CP) was not effectively controlled by high efficiency particulate air (HEPA) filters.((1)) This then raised a concern that the existing air monitoring methods, which utilize polytetrafluoroethylene (a.k.a. PTFE, or Teflon) or glass fiber filters for evaluation of antineoplastics such as CP in air may also be ineffective for collection and quantification of such agents. It was decided that further evaluation of the existing filter method for monitoring antineoplastics in air be conducted. This evaluation determined that the filter method of monitoring was minimally effective for some antineoplastic agents, and that an alternate method of monitoring should be sought. The method subsequently developed utilizes a solid sorbent tube, Anasorb 708, a methacrylic acid polymer. Evaluation of this sorbent tube for adsorption and desorption properties found it had a greater than 90 percent recovery for both CP and ifosfamide. Other agents evaluated included 5-fluorouracil, doxorubicin, and paclitaxel. All three agents were able to be detected and measured by use of Anasorb 708 solid sorbent tube. Validation of the method was then conducted with air pulled through the tubes via attachment to an air manifold system at air flows ranging from 1.5 to approximately 4.0 liters per minute for up to 24 hours. This evaluation did validate the Anasorb 708 tube as an effective media for collection of airborne concentrations of CP from less than 1 microgram up to approximately 2 mg (2000 microgram) per tube. This corresponds to a concentration range of approximately 0.7 microgram/m(3) (0.0007 mg/m(3)) to 0.7 mg/m(3) in a 5.76 m(3) volume of air. This method can provide accurate information on airborne concentrations of CP for purposes of conducting risk assessments or evaluation of risk management methods.

  3. Assessment of offshore New Jersey sources of Beach replenishment sand by diversified application of geologic and geophysical methods

    USGS Publications Warehouse

    Waldner, J.S.; Hall, D.W.; Uptegrove, J.; Sheridan, R.E.; Ashley, G.M.; Esker, D.

    1999-01-01

    . The seismograms are then correlated to the digital seismic profile to confirm reflected events. They are particularly useful where individual reflection events cannot be detected but a waveform generated by several thin lithologic units can be recognized. Progress in application of geologic and geophysical methods provides advantages in detailed sediment analysis and volumetric estimation of offshore sand ridges. New techniques for current and ongoing beach replenishment projects not only expand our knowledge of the geologic processes involved in sand ridge origin and development, but also improve our assessment of these valuable resources. These reconnaissance studies provide extensive data to the engineer regarding the suitability and quantity of sand and can optimize placement and analysis of vibracore samples.Beach replenishment serves the dual purpose of maintaining a source of tourism and recreation while protecting life and property. Research has improved both data collection and interpretation of seismic surveys and vibracore analysis for projects investigating sand ridges offshore of New Jersey. The New Jersey Geological Survey in cooperation with Rutgers University is evaluating the capabilities of digital seismic data to analyze sand ridges. The printing density of analog systems limits the dynamic range to about 24 dB. Digital acquisition systems with dynamic ranges about 100 dB can permit enhanced seismic profiles by trace static correction, deconvolution, automatic gain scaling, horizontal stacking and digital filtering.

  4. A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters.

    PubMed

    Li, Hanlun; Zhang, Aiwu; Hu, Shaoxing

    2015-07-20

    This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels.

  5. A new diagnostic method for separating airborne and structureborne noise radiated by plates with applications for propeller driven aircraft

    NASA Technical Reports Server (NTRS)

    Mcgary, Michael C.

    1988-01-01

    The anticipated application of advanced turboprop propulsion systems is expected to increase the interior noise of future aircraft to unacceptably high levels. The absence of technically and economically feasible noise source-path diagnostic tools has been a prime obstacle in the development of efficient noise control treatments for propeller-driven aircraft. A new diagnostic method that permits the separation and prediction of the fully coherent airborne and structureborne components of the sound radiated by plates or thin shells has been developed. Analytical and experimental studies of the proposed method were performed on an aluminum plate. The results of the study indicate that the proposed method could be used in flight, and has fewer encumbrances than the other diagnostic tools currently available.

  6. A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters

    PubMed Central

    Li, Hanlun; Zhang, Aiwu; Hu, Shaoxing

    2015-01-01

    This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. PMID:26205264

  7. Individual tree crown delineation using localized contour tree method and airborne LiDAR data in coniferous forests

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Yu, Bailang; Wu, Qiusheng; Huang, Yan; Chen, Zuoqi; Wu, Jianping

    2016-10-01

    Individual tree crown delineation is of great importance for forest inventory and management. The increasing availability of high-resolution airborne light detection and ranging (LiDAR) data makes it possible to delineate the crown structure of individual trees and deduce their geometric properties with high accuracy. In this study, we developed an automated segmentation method that is able to fully utilize high-resolution LiDAR data for detecting, extracting, and characterizing individual tree crowns with a multitude of geometric and topological properties. The proposed approach captures topological structure of forest and quantifies topological relationships of tree crowns by using a graph theory-based localized contour tree method, and finally segments individual tree crowns by analogy of recognizing hills from a topographic map. This approach consists of five key technical components: (1) derivation of canopy height model from airborne LiDAR data; (2) generation of contours based on the canopy height model; (3) extraction of hierarchical structures of tree crowns using the localized contour tree method; (4) delineation of individual tree crowns by segmenting hierarchical crown structure; and (5) calculation of geometric and topological properties of individual trees. We applied our new method to the Medicine Bow National Forest in the southwest of Laramie, Wyoming and the HJ Andrews Experimental Forest in the central portion of the Cascade Range of Oregon, U.S. The results reveal that the overall accuracy of individual tree crown delineation for the two study areas achieved 94.21% and 75.07%, respectively. Our method holds great potential for segmenting individual tree crowns under various forest conditions. Furthermore, the geometric and topological attributes derived from our method provide comprehensive and essential information for forest management.

  8. Digital data from the Great Sand Dunes airborne gravity gradient survey, south-central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Abraham, J.D.; Grauch, V.J.S.; Labson, V.F.; Hodges, G.

    2013-01-01

    This report contains digital data and supporting explanatory files describing data types, data formats, and survey procedures for a high-resolution airborne gravity gradient (AGG) survey at Great Sand Dunes National Park, Alamosa and Saguache Counties, south-central Colorado. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve. The data described were collected from a high-resolution AGG survey flown in February 2012, by Fugro Airborne Surveys Corp., on contract to the U.S. Geological Survey. Scientific objectives of the AGG survey are to investigate the subsurface structural framework that may influence groundwater hydrology and seismic hazards, and to investigate AGG methods and resolution using different flight specifications. Funding was provided by an airborne geophysics training program of the U.S. Department of Defense's Task Force for Business & Stability Operations.

  9. Environmental and Engineering Geophysical University at SAGEEP 2008: Geophysical Instruction for Non-Geophysicists

    SciTech Connect

    Jeffrey G. Paine

    2009-03-13

    The Environmental and Engineering Geophysical Society (EEGS), a nonprofit professional organization, conducted an educational series of seminars at the Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP) in Philadelphia in April 2008. The purpose of these seminars, conducted under the name Environmental and Engineering Geophysical University (EEGU) over three days in parallel with the regular SAGEEP technical sessions, was to introduce nontraditional geophysical conference attendees to the appropriate use of geophysics in environmental and engineering projects. Five half-day, classroom-style sessions were led by recognized experts in the application of seismic, electrical, gravity, magnetics, and ground-penetrating radar methods. Classroom sessions were intended to educate regulators, environmental program managers, consultants, and students who are new to near-surface geophysics or are interested in learning how to incorporate appropriate geophysical approaches into characterization or remediation programs or evaluate the suitability of geophysical methods for general classes of environmental or engineering problems.

  10. Multi-decadal surface temperature trends in East Antarctica inferred from borehole firn temperature measurements and geophysical inverse methods

    NASA Astrophysics Data System (ADS)

    Muto, Atsuhiro

    The climate trend of the Antarctic interior remains unclear relative to the rest of the globe because of a lack of long-term weather records. Recent studies by other authors utilizing sparse available records, satellite data, and models have estimated a significant warming trend in the near-surface air temperature in West Antarctica and weak and poorly constrained warming trend in East Antarctica for the past 50 years. In this dissertation, firn thermal profiling was used to detect multi-decadal surface temperature trends in the interior of East Antarctica where few previous records of any kind exist. The surface temperature inversion from firn temperature profiles provides a climate reconstruction independent of firn chemistry, sparse weather data, satellite data, or ice cores, and therefore may be used in conjunction with these data sources for corroboration of climate trends over the large ice sheets. During the Norwegian-U.S. IPY Scientific Traverse of East Antarctica, in the austral summers of 2007--08 and 2008--09, thermal-profiling telemetry units were installed at five locations. Each unit consists of 16 PRTs (Platinum Resistance Thermometers) distributed in a back-filled borehole of 80 to 90 m deep. The accuracy of the temperature measurement is 0.03 K. Geophysical inverse methods (linearized and Monte Carlo inversion) were applied to one full year of data collected from three units installed near the ice divide in the Dome Fuji/Pole of Inaccessibility region and one on Recovery Lake B, situated >500 km south to south-west of and >1000 m lower in altitude than sites near the ice divide. Three sites near the ice divide indicate that the mean surface temperatures have increased approximately 1 to 1.5 K within the past ˜50 years although the onset and the duration of this warming vary by site. On the other hand, slight cooling to no change was detected at the Recovery Lake B site. Although uncertainties remain due to limitations of the method, these results

  11. Investigation of the potential for concealed base-metal mineralization at the Drenchwater Creek Zn-Pb-Ag occurrence, northern Alaska, using geology, reconnaissance geochemistry, and airborne electromagnetic geophysics

    USGS Publications Warehouse

    Graham, Garth E.; Deszcz-Pan, Maria; Abraham, Jared; Kelley, Karen D.

    2011-01-01

    No drilling has taken place at the Drenchwater occurrence, so alternative data sources (for example, geophysics) are especially important in assessing possible indicators of mineralization. Data from the 2005 electromagnetic survey define the geophysical character of the rocks at Drenchwater and, in combination with geological and surface-geochemical data, can aid in assessing the possible shallow (up to about 50 m), subsurface lateral extent of base-metal sulfide accumulations at Drenchwater. A distinct >3-km-long electromagnetic conductive zone (observed in apparent resistivity maps) coincides with, and extends further westward than, mineralized shale outcrops and soils anomalously high in Pb concentrations within the Kuna Formation; this conductive zone may indicate sulfide-rich rock. Models of electrical resistivity with depth, generated from inversion of electromagnetic data, which provide alongflight-line conductivity-depth profiles to between 25 and 50 m below ground surface, show that the shallow subsurface conductive zone occurs in areas of known mineralized outcrops and thins to the east. Broader, more conductive rock along the western ~1 km of the geophysical anomaly does not reach ground surface. These data suggest that the Drenchwater deposit is more extensive than previously thought. The application of inversion modeling also was applied to another smaller geochemical anomaly in the Twistem Creek area. The results are inconclusive, but they suggest that there may be a local conductive zone, possibly due to sulfides.

  12. Unmanned Aircraft Systems for Rapid Near Surface Geophysical Measurements

    NASA Astrophysics Data System (ADS)

    Stoll, J. B.

    2013-08-01

    This paper looks at some of the unmanned aircraft systems (UAS) options and deals with a magnetometer sensor system which might be of interest in conducting rapid near surface geophysical measurements. Few of the traditional airborne geophysical sensors are now capable of being miniaturized to sizes and payload within mini UAS limits (e.g. airborne magnetics, gamma ray spectrometer). Here the deployment of a fluxgate magnetometer mounted on an UAS is presented demonstrating its capability of detecting metallic materials that are buried in the soil. The effectiveness in finding ferrous objects (e.g. UXO, landslides) is demonstrated in two case studies.

  13. The search for "Yvonne": a case example of the delineation of a grave using near-surface geophysical methods.

    PubMed

    Nobes, D C

    2000-05-01

    Shallow electromagnetic (EM) and ground-penetrating radar (GPR) surveys were conducted in an area north of Auckland, New Zealand to assist the search for human remains. The body had been buried for almost 12 years in a plantation forest that was irregularly disrupted and modified by tree harvesting and the partial removal of stumps. EM identified anomalous areas of potential interest, because a target need only be nearby to generate an EM response. GPR was then used to map subsurface layering, layering disruption, and buried objects, immediately adjacent to an EM anomaly. Because of the nature of the site, numerous geophysical anomalies were present. GPR was particularly sensitive to site disturbance resulting from the forestry operations. An isolated EM anomaly on the fringes of an expanded survey area was coincident with the location of the body. Whether for criminal investigations or for archaeological work, a combination of geophysical techniques is recommended.

  14. Application of multiple geophysical methods to hydrologic and environmental investigations at US Marine Corps installations in North Carolina

    SciTech Connect

    Cardinell, A.P.; Daniel, C.C. III

    1997-10-01

    Hydrologic information for ongoing environmental studies at two U.S. Marine Corps Bases in the Coastal Plain Province of North Carolina was obtained by using a combination of high-resolution land seismic reflection, continuous marine seismic profiling, and borehole geophysics, that included vertical seismic profiling. The geometry of areas of missing confining units at the southern end of Cherry Point Marine Corps Air Station was mapped by using land seismic-reflection compressional (P) waves, marine seismic profiling, and borehole-geophysical and lithologic data from more than 100 water-supply and monitoring wells. The hydrogeologic framework at Camp Lejeune was mapped by using 100 miles of continuous single-channel, marine seismic-profiling data that were correlated with land-based borehole geophysical and lithologic data from 180 water-supply, monitoring, and stratigraphic test wells. These data are being used by both Marine Corps Bases to manage drinking-water supplies and plan investigations of hazardous-waste sites.

  15. Geohydrologic assessment of fractured crystalline bedrock on the southern part of Manhattan, New York, through the use of advanced borehole geophysical methods

    USGS Publications Warehouse

    Stumm, F.; Chu, A.; Joesten, P.K.; Lane, J.W.

    2007-01-01

    Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, NY in preparation of the construction of a new water tunnel. The study area is located in a highly urbanized part of New York City. The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an overall southwest-to northwest-dipping foliation. Most of the fractures intersected are nearly horizontal or have moderate- to high-angle northwest or eastward dip azimuths. Heat-pulse flowmeter logs obtained under nonpumping (ambient) and pumping conditions, together with other geophysical logs, delineated transmissive fracture zones in each borehole. Water-level and flowmeter data suggest the fractured-rock ground-water-flow system is interconnected. The 60 MHz directional borehole-radar logs delineated the location and orientation of several radar reflectors that did not intersect the projection of the borehole. A total of 53 faults intersected by the boreholes have mean orientation populations of N12??W, 66??W and N11??W, 70??E. A total of 77 transmissive fractures delineated using the heat-pulse flowmeter have mean orientations of N11??E, 14??SE (majority) and N23??E, 57??NW (minority). The transmissivity of the bedrock boreholes ranged from 0.7 to 870 feet squared (ft2) per day (0.07 to 81 metres squared (m2) per day). ?? 2007 Nanjing Institute of Geophysical Prospecting.

  16. Asteroid Surface Geophysics

    NASA Astrophysics Data System (ADS)

    Murdoch, N.; Sánchez, P.; Schwartz, S. R.; Miyamoto, H.

    The regolith-covered surfaces of asteroids preserve records of geophysical processes that have occurred both at their surfaces and sometimes also in their interiors. As a result of the unique microgravity environment that these bodies possess, a complex and varied geophysics has given birth to fascinating features that we are just now beginning to understand. The processes that formed such features were first hypothesized through detailed spacecraft observations and have been further studied using theoretical, numerical, and experimental methods that often combine several scientific disciplines. These multiple approaches are now merging toward a further understanding of the geophysical states of the surfaces of asteroids. In this chapter we provide a concise summary of what the scientific community has learned so far about the surfaces of these small planetary bodies and the processes that have shaped them. We also discuss the state of the art in terms of experimental techniques and numerical simulations that are currently being used to investigate regolith processes occurring on small-body surfaces and that are contributing to the interpretation of observations and the design of future space missions.

  17. Airborne measurements of stratospheric constituents over Antarctica in the austral spring 1987. I - Method and ozone observations

    NASA Technical Reports Server (NTRS)

    Mankin, William G.; Coffey, M. T.

    1989-01-01

    A Fourier transform spectrometer was flown aboard a DC-8 on 10 flights over Antarctica during August and September, 1987, as part of the Airborne Antarctic Ozone Experiment (AAOE). Observing the sun at infrared wavelengths, it was possible to determine the integrated column amount above the flight altitude for ozone and a number of other chemical species that are believed to be important in the perturbed chemistry of the 'ozone hole'. The paper describes the method, the observations, the data analysis procedure, and the ozone results. During the observation period, ozone developed a steep gradient near the edge of the polar vortex; deep within the vortex, the average ozone column decreased by about 1.6 percent per day during September.

  18. Optimization and geophysical inverse problems

    SciTech Connect

    Barhen, J.; Berryman, J.G.; Borcea, L.; Dennis, J.; de Groot-Hedlin, C.; Gilbert, F.; Gill, P.; Heinkenschloss, M.; Johnson, L.; McEvilly, T.; More, J.; Newman, G.; Oldenburg, D.; Parker, P.; Porto, B.; Sen, M.; Torczon, V.; Vasco, D.; Woodward, N.B.

    2000-10-01

    A fundamental part of geophysics is to make inferences about the interior of the earth on the basis of data collected at or near the surface of the earth. In almost all cases these measured data are only indirectly related to the properties of the earth that are of interest, so an inverse problem must be solved in order to obtain estimates of the physical properties within the earth. In February of 1999 the U.S. Department of Energy sponsored a workshop that was intended to examine the methods currently being used to solve geophysical inverse problems and to consider what new approaches should be explored in the future. The interdisciplinary area between inverse problems in geophysics and optimization methods in mathematics was specifically targeted as one where an interchange of ideas was likely to be fruitful. Thus about half of the participants were actively involved in solving geophysical inverse problems and about half were actively involved in research on general optimization methods. This report presents some of the topics that were explored at the workshop and the conclusions that were reached. In general, the objective of a geophysical inverse problem is to find an earth model, described by a set of physical parameters, that is consistent with the observational data. It is usually assumed that the forward problem, that of calculating simulated data for an earth model, is well enough understood so that reasonably accurate synthetic data can be generated for an arbitrary model. The inverse problem is then posed as an optimization problem, where the function to be optimized is variously called the objective function, misfit function, or fitness function. The objective function is typically some measure of the difference between observational data and synthetic data calculated for a trial model. However, because of incomplete and inaccurate data, the objective function often incorporates some additional form of regularization, such as a measure of smoothness

  19. Geophysical Investigations in the Caucasus (1925 - 2012): Initial, Basic and Modern Stages

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.

    2012-04-01

    testing different geophysical methods and methodologies in complicated environments. Airborne magnetic and gravity surveys covered all the Caucasus, regional seismic and magnetotelluric studies were used as reference profiles for deep structure investigation. Numerous effective applications of geophysical methods for searching ore, oil&gas deposits, building raw, fresh water localization, solving engineering, etc. was demonstrated. Seismological investigations (including different methods) were widely applied throughout the entire Caucasian region. Satellite geophysical examinations were successfully combined with other methods. Finally, destruction of the former Soviet Union in 1991 (beginning of the modern stage) caused a sharp common decreasing of the geophysical activity in this region. Only foreign oil-&gas companies (mainly American and England) demonstrated some industrial geophysical activity basically in the Caspian Sea. In the last few years the situation began to straighten out, especially in the field of seismology. This presentation is based of the author's experience (e.g., Eppelbaum, 1989, 1991, 2009; Eppelbaum et al., 1987; Eppelbaum and Finkelstein, 1998; Eppelbaum and Khesin, 1988, 1992, 2002, 2004, 2011, 2012; Eppelbaum and Mishne, 2011; Eppelbaum et al., 2003, 2004; Khesin et al., 1988, 1993a, 1993b, 1996, 1997; Khesin and Eppelbaum, 1986, 1994, 1997, 2007; Pilchin and Eppelbaum, 1997, 2011) and corresponding publications and reviews of other authors.

  20. Apparatus and methods for monitoring the concentrations of hazardous airborne substances, especially lead

    DOEpatents

    Zaromb, Solomon

    2004-07-13

    Air is sampled at a rate in excess of 100 L/min, preferably at 200-300 L/min, so as to collect therefrom a substantial fraction, i.e., at least 20%, preferably 60-100%, of airborne particulates. A substance of interest (analyte), such as lead, is rapidly solubilized from the the collected particulates into a sample of liquid extractant, and the concentration of the analyte in the extractant sample is determined. The high-rate air sampling and particulate collection may be effected with a high-throughput filter cartridge or with a recently developed portable high-throughput liquid-absorption air sampler. Rapid solubilization of lead is achieved by a liquid extractant comprising 0.1-1 M of acetic acid or acetate, preferably at a pH of 5 or less and preferably with inclusion of 1-10% of hydrogen peroxide. Rapid determination of the lead content in the liquid extractant may be effected with a colorimetric or an electroanalytical analyzer.

  1. COLLECTION OF AIRBORNE PARTICLES BY A HIGH-GRADIENT PERMANENT MAGNETIC METHOD

    SciTech Connect

    Cheng, Mengdawn; Allman, Steve L; Ludtka, Gerard Michael; Avens, Larry R

    2014-01-01

    We report on the use of magnetic force in collection of airborne particles by a high- gradient permanent magnetic separation (HGPMS) device. Three aerosol particles of different magnetic susceptibility (NaCl, CuO, and Fe2O3) were generated in the electrical mobility size range of 10 to 200 nm and were used to study HGPMS collection. One HGPMS matrix element, made of stainless steel wool, was used in the device configuration. Three flow rates were selected to simulate the environmental wind speeds of interest to the study. Magnetic force was found to exhibit an insignificant effect on the separation of NaCl particles, even in the HGPMS configuration. Diffusion was a major mechanism in the removal of the diamagnetic particles; however, diffusion is insignificant under the influence of a high-gradient magnetic field for paramagnetic or ferromagnetic particles. The HGPMS showed high-performance collection (> 99%) of paramagnetic CuO and ferromagnetic Fe2O3 particles for particle sizes greater than or equal to 60 nm. As the wind speed increases, the influence of the magnetic force weakens, and the capability to remove particles from the gas stream diminishes. The results suggest that the HGPMS principle could be explored for development of an advanced miniaturized passive aerosol collector.

  2. Evaluation of the potential of the Clare Basin, SW Ireland, for onshore carbon sequestration using electromagnetic geophysical methods

    NASA Astrophysics Data System (ADS)

    Llovet, Joan Campanya i.; Ogaya, Xenia; Jones, Alan G.; Rath, Volker; Ledo, Juanjo; McConnell, Brian

    2015-04-01

    Carbon capture, sequestration and long-term storage (CCS) is a critically important and intellectually and technologically challenging bridging technology for assisting humanity to migrate from its dependence on fossil fuels to green energy over the next half century. The IRECCSEM project (www.ireccsem.ie) is a Science Foundation Ireland Investigator Project to evaluate Ireland's potential for onshore carbon sequestration in saline aquifers by integrating new electromagnetic geophysical data with existing geophysical and geological data. The main goals of the project are to determine porosity and permeability values of the potential reservoir formation as well as to evaluate the integrity of the seal formation. During the summer of 2014, a magnetotelluric (MT) survey was carried out in the Carboniferous Clare Basin (SW Ireland). Data from a total of 140 sites were acquired, including audio-magnetotelluric (AMT), broadband magnetotelluric (BBMT) and long period magnetotelluric (LMT) data. These new data added to existing MT data acquired at 32 sites during a feasibility pilot survey conducted in 2010. The nominal space between the 2014 sites was 0.6 km between AMT sites, 1.2 km between BBMT sites and 8 km between LMT sites. The electrical resistivity distribution beneath the survey area was constrained using three different types of electromagnetic data: MT impedance tensor responses (Z), geomagnetic transfer functions (GTF) and inter-station horizontal magnetic transfer-functions (HMT). A newly-computed code based on the Generalized Archie's Law and available data from boreholes were used to relate the obtained geoelectrical model to rock properties (i.e. porosity and permeability). The results are compared to independent geological and geophysical data for superior interpretation.

  3. Comparing the suitability of geophysical methods in the study of a cave in marbles: A case study of Gruta de las Maravillas (Aracena, Southwest Spain)

    NASA Astrophysics Data System (ADS)

    José Martínez Moreno, Francisco; Galindo Zaldívar, Jesús; Pedrera Parias, Antonio; Ullod, Teresa Teixidó i.; Ruano Roca, Patricia; Peña Ruano, Jose Antonio; González Castillo, Lourdes; Ruiz Constan, Ana; López Chicano, Manuel; Martín Rosales, Wenceslao

    2014-05-01

    Different geophysical methods have been applied to determine the geometry of caves, considering the host rock, depth, dimension, presence of water and other parameters. The Gruta de las Maravillas cave is located in marbles interlayered with gneiss, quartzite and granodiorite along the suture between South Portuguese and Ossa Morena zone. This cave is probably formed as a consequence of the presence of pyrite and iron oxides mineralization that interacted with the surrounding marble host rocks. In order to analyze the continuity of the Gruta de las Maravillas cave (Aracena, southwest Spain) geophysical methods has been used on the known cave in order to check their suitability. These results allow investigating the prolongation of the cave in surrounding areas, performing a comprehensive study of the Cerro del Castillo hill containing the cavity. Microtopography with differential GPS and cave topography with an accuracy of 0.01 m were measured. The first geophysical method employed were a regional microgravity, with and SCINTREX CG-5 gravimeter that reaches an accuracy up to 0.001 mGal. In the obtained residual anomaly map, negative values are associated with negative density contrast, which are related to the known cave position. In addition, residual gravity minima suggest the presence of other unknown cavities. The anomalies attributed to possible new shallow and deep caves have been studied in a second step with the application of other eight detailed geophysical methods along profiles to test the response of each of them to the presence of cavities: microgravity, magnetic, electrical resistivity tomography, induced polarization, seismic P-waves velocity tomography, ray tracing coverage, common offset and ground-penetrating radar. Moreover, the known cave has walls covered with iron oxides that determine magnetic anomaly minima and intermediate resistivity values (~2000 ohm.m) on the ERT profiles versus the host marble rocks (~45000 ohm.m). After a detailed

  4. Experimental Investigations on Airborne Gravimetry Based on Compressed Sensing

    PubMed Central

    Yang, Yapeng; Wu, Meiping; Wang, Jinling; Zhang, Kaidong; Cao, Juliang; Cai, Shaokun

    2014-01-01

    Gravity surveys are an important research topic in geophysics and geodynamics. This paper investigates a method for high accuracy large scale gravity anomaly data reconstruction. Based on the airborne gravimetry technology, a flight test was carried out in China with the strap-down airborne gravimeter (SGA-WZ) developed by the Laboratory of Inertial Technology of the National University of Defense Technology. Taking into account the sparsity of airborne gravimetry by the discrete Fourier transform (DFT), this paper proposes a method for gravity anomaly data reconstruction using the theory of compressed sensing (CS). The gravity anomaly data reconstruction is an ill-posed inverse problem, which can be transformed into a sparse optimization problem. This paper uses the zero-norm as the objective function and presents a greedy algorithm called Orthogonal Matching Pursuit (OMP) to solve the corresponding minimization problem. The test results have revealed that the compressed sampling rate is approximately 14%, the standard deviation of the reconstruction error by OMP is 0.03 mGal and the signal-to-noise ratio (SNR) is 56.48 dB. In contrast, the standard deviation of the reconstruction error by the existing nearest-interpolation method (NIPM) is 0.15 mGal and the SNR is 42.29 dB. These results have shown that the OMP algorithm can reconstruct the gravity anomaly data with higher accuracy and fewer measurements. PMID:24647125

  5. Geophysical flight line flying and flight path recovery utilizing the Litton LTN-76 inertial navigation system

    SciTech Connect

    Mitkus, A.F.; Cater, D.; Farmer, P.F.; Gay, S.P. Jr.

    1981-11-01

    The Litton LTN-76 Inertial Navigation Systems (INS) with Inertial Track guidance System (ITGS) software is geared toward the airborne survey industry. This report is a summary of tests performed with the LTN-76 designed to fly an airborne geophysical survey as well as to recover the subsequent flight path utilizing INS derived coordinates.

  6. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  7. Geophex Airborne Unmanned Survey System

    SciTech Connect

    Won, I.L.; Keiswetter, D.

    1995-12-31

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results.

  8. Sustainable urban development and geophysics

    NASA Astrophysics Data System (ADS)

    Liu, Lanbo; Chan, L. S.

    2007-09-01

    investigated [2]. The first objective of urban geophysics is to study systematically the geophysical fields in cities, searching for principles and processes governing the intensity and patterns of variation of the geophysical properties, as well as the potential consequences on the biosphere. Secondly, geophysics has already been found to be a useful tool for subsurface detection and investigation, hazard mitigation, and assessment of environmental contamination. Geophysicists have documented numerous cases of successful applications of geophysical techniques to solve problems related to hazard mitigation, safeguarding of lifeline infrastructure and urban gateways (air- and sea-ports, railway and highway terminals), archaeological and heritage surveys, homeland security, urban noise control, water supplies, sanitation and solid waste management etc. In contrast to conventional geophysical exploration, the undertaking of geophysical surveys in an urban setting faces many new challenges and difficulties. First of all, the ambient cultural noise in cities caused by traffic, electromagnetic radiation and electrical currents often produce undesirably strong interference with geophysical measurements. Secondly, subsurface surveys in an urban area are often targeted at the uppermost several metres of the ground, which are the most heterogeneous layers with many man-made objects. Thirdly, unlike conventional geophysical exploration which requires resolution in the order of metres, many urban geophysical surveys demand a resolution and precision in the order of centimetres or even millimetres. Finally restricted site access and limited time for conducting geophysical surveys, regulatory constraints, requirements for traffic management and special logistical arrangements impose additional difficulties. All of these factors point to the need for developing innovative research methods and geophysical instruments suitable for use in urban settings. This special issue on 'Sustainable urban

  9. Determination of the Lithosphere-Asthenosphere Boundary (LAB) beneath the Nógrád-Gömör Volcanic Field by combined geophysical (magnetotellurics) and geochemical methods

    NASA Astrophysics Data System (ADS)

    Novák, Attila; Klébesz, Rita; Szabó, Csaba; Patkó, Levente; Liptai, Nóra; Kovács, Zoltán; Wesztergom, Viktor; Ádám, Antal; Lemperger, István; Kis, Árpád; Molnár, Csaba; Szendrői, Judit

    2014-05-01

    Understanding the fundamental role of LAB is substantial for the investigation of the geodynamic evolution of the Earth. The LAB depths can be estimated by different geophysical methods (seismology, magnetotellurics), however these depths are controversial. It has been emphasized in the literature that combined geophysical and geochemical approach may lead to better understanding of these depths. The magnetotellurics (MT) is very powerful method because it indicates the sudden increase in conductivity at the LAB. The mantle xenoliths (small fragments of the lithospheric mantle) provide the information to reconstruct their P-T paths. In the Carpathian-Pannon region (CPR) five, well-studied occurrences of mantle xenoliths-bearing Plio-Pleistocene alkali basalts are known, which makes the CPR a very promising area for investigating the inconsistency in the LAB estimates. As a test area Nógrád-Gömör Volcanic Field (NGVF) has been chosen. The host basalt erupted at the NGVF collected mantle xenoliths from a small volume of the upper mantle in a depth of about 40-50 km. The major element geochemistry of the studied xenoliths indicates that most of them represent common lherzolitic mantle, whereas others show strong wehrlitisation process. This metasomatism is supposed to be caused by a migrating mafic melt agent, resulting in the transformation of a large portion of lherzolite to wehrlite beneath the NGVF, possibly just below the crust mantle boundary. In aim to detect the LAB at the research area and find the correlation with petrologic and geochemical results we carried out MT deep soundings. The campaign contained 12 long period MT stations with 3-5 km average spacing along 60 km long profile SSE to NNW direction. This presentation summarizes the preliminary results of the combined geophysical and geochemical approaches to determine the LAB depths.

  10. Continental crust: a geophysical approach

    SciTech Connect

    Meissner, R.

    1986-01-01

    This book develops an integrated and balanced picture of present knowledge of the continental crust. Crust and lithosphere are first defined, and the formation of crusts as a general planetary phenomenon is described. The background and methods of geophysical studies of the earth's crust and the collection of related geophysical parameters are examined. Creep and friction experiments and the various methods of radiometric age dating are addressed, and geophysical and geological investigations of the crustal structure in various age provinces of the continents are studied. Specific tectonic structures such as rifts, continental margins, and geothermal areas are discussed. Finally, an attempt is made to give a comprehensive view of the evolution of the continental crust and to collect and develop arguments for crustal accretion and recycling. 647 references.

  11. Assessment of the capabilities of the tICA and stICA methods for geophysical signal separation in GRACE data

    NASA Astrophysics Data System (ADS)

    Börgens, Eva; Rangelova, Elena; Sideris, Michael; Kusche, Jürgen

    2013-04-01

    We investigate the potential of the tICA and stICA methods for separating geophysical signals in GRACE gravity data. Since the start of the Gravity Recovery and Climate Experiment (GRACE) satellite mission in 2002, GRACE has provided us with global gravity data with a spatial resolution of a few hundred kilometers and a temporal resolution of one month, 10 days or even a week. These data represent the total, integrated gravity change inducing by mass signals related to hydrological processes, post glacial rebound (PGR), ice mass change and others. Isolating a particular mass signal may be accomplished by removing all others using geophysical background models, but these are usually not perfect. Therefore methods are required for separating data into the different geophysical signals on the basis of their statistical properties. To this end, we assess the potential of temporal Independent Component Analysis (tICA) and spatio-temporal Independent Component Analysis (stICA). The tICA method is based on the assumption of statistical independence of signals in the temporal domain and thus separates the GRACE-observed mass changes into maximal independent source signals. In comparison, stICA maximizes both the temporal and spatial independence. These two ICA methods are compared to the conventional Principle Component Analysis (PCA). We test them on GRACE data with respect to their ability to separate the hydrology signal from a trend signal not induced by hydrological processes, such as post glacial rebound (PGR). In addition, we investigate whether they are capable of separating the hydrological signal in annual and semi-annual components. We analyze both simulated and CSR GRACE water mass anomalies (January 2003 -December 2010). The simulated mass anomalies are composed of outputs of hydrologic, PGR, ice loss and ocean bottom pressure models. The two ICA methods are capable of separating the trend and annual hydrology signals both on a global and regional scale (North

  12. Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

    PubMed Central

    Buttner, M P; Stetzenbach, L D

    1993-01-01

    Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments. PMID:8439150

  13. Spectrum correction algorithm for detectors in airborne radioactivity monitoring equipment NH-UAV based on a ratio processing method

    NASA Astrophysics Data System (ADS)

    Cao, Ye; Tang, Xiao-Bin; Wang, Peng; Meng, Jia; Huang, Xi; Wen, Liang-Sheng; Chen, Da

    2015-10-01

    The unmanned aerial vehicle (UAV) radiation monitoring method plays an important role in nuclear accidents emergency. In this research, a spectrum correction algorithm about the UAV airborne radioactivity monitoring equipment NH-UAV was studied to measure the radioactive nuclides within a small area in real time and in a fixed place. The simulation spectra of the high-purity germanium (HPGe) detector and the lanthanum bromide (LaBr3) detector in the equipment were obtained using the Monte Carlo technique. Spectrum correction coefficients were calculated after performing ratio processing techniques about the net peak areas between the double detectors on the detection spectrum of the LaBr3 detector according to the accuracy of the detection spectrum of the HPGe detector. The relationship between the spectrum correction coefficient and the size of the source term was also investigated. A good linear relation exists between the spectrum correction coefficient and the corresponding energy (R2=0.9765). The maximum relative deviation from the real condition reduced from 1.65 to 0.035. The spectrum correction method was verified as feasible.

  14. Airborne Particles.

    ERIC Educational Resources Information Center

    Ojala, Carl F.; Ojala, Eric J.

    1987-01-01

    Describes an activity in which students collect airborne particles using a common vacuum cleaner. Suggests ways for the students to convert their data into information related to air pollution and human health. Urges consideration of weather patterns when analyzing the results of the investigation. (TW)

  15. Airborne Imagery

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ATM (Airborne Thematic Mapper) was developed for NSTL (National Space Technology Companies) by Daedalus Company. It offers expanded capabilities for timely, accurate and cost effective identification of areas with prospecting potential. A related system is TIMS, Thermal Infrared Multispectral Scanner. Originating from Landsat 4, it is also used for agricultural studies, etc.

  16. Muon tomography of the Soufrière of Guadeloupe (Lesser Antilles): Comparison with other geophysical imaging methods and assessment of volcanic risks

    NASA Astrophysics Data System (ADS)

    Gibert, D.; Lesparre, N.; Marteau, J.; Taisne, B.; Nicollin, F.; Coutant, O.

    2011-12-01

    adapted to brought constraints on flank destabilization and hydrothermal circulation models. Tanaka et al., Three dimensional computational axial tomography scan of a volcano with cosmic ray muon radiography, J. Geophys. Res., 115, B12332, doi:10.1029/2010JB007677, 2010. Gibert et al., Muon Tomography: Plans for Observations in the Lesser Antilles, Earth Planets and Space, Vol. 52, 153-165, doi: 10.5047/eps.2009.07.003, 2010. Lesparre et al., Geophysical muon imaging: feasibility and limits, Geophysical Journal International, Vol. 183, 1348-1361, doi: 10.1111/j.1365-246X.2010.04790.x, 2010. Lesparre et al., Design and Operation of a Field Telescope for Cosmic Ray Geophysical Tomography, Nuclear Instruments and Methods in Physics Research A, to appear, 2011a. Lesparre et al., Bayesian Dual Inversion of Experimental Telescope Acceptance and Integrated Flux for Geophysical Muon Tomography, Geophysical Journal International, to appear, 2011b.

  17. Airborne concentrations of peanut protein.

    PubMed

    Johnson, Rodney M; Barnes, Charles S

    2013-01-01

    Food allergy to peanut is a significant health problem, and there are reported allergic reactions to peanuts despite not eating or having physical contact with peanuts. It is presumed that an allergic reaction may have occurred from inhalation of airborne peanut allergens. The purpose of this study was to detect the possible concentrations of airborne peanut proteins for various preparations and during specific activities. Separate Ara h 1 and Ara h 2 monoclonal enzyme-linked immunosorbent assays and a polyclonal sandwich enzyme immunoassay for peanuts were used to detect the amount of airborne peanut protein collected using a Spincon Omni 3000 air collector (Sceptor Industries, Inc., Kansas City, MO) under different peanut preparation methods and situations. Air samples were measured for multiple peanut preparations and scenarios. Detectable amounts of airborne peanut protein were measured using a whole peanut immunoassay when removing the shells of roasted peanut. No airborne peanut allergen (Ara h 1 or Ara h 2) or whole peanut protein above the LLD was measured in any of the other peanut preparation collections. Ara h 1, Ara h 2, and polyclonal peanut proteins were detected from water used to boil peanuts. Small amounts of airborne peanut protein were detected in the scenario of removing shells from roasted peanuts; however, Ara h 1 and Ara h 2 proteins were unable to be consistently detected. Although airborne peanut proteins were detected, the concentration of airborne peanut protein that is necessary to elicit a clinical allergic reaction is unknown.

  18. Constructing Regional Groundwater Models from Geophysical Data of Varying Type, Age, and Quality

    NASA Astrophysics Data System (ADS)

    Christiansen, A. V.; Auken, E.; Marker, P. A.; Vilhelmsen, T. N.; Foged, N.; Wernberg, T.; Bauer-Gottwein, P.

    2015-12-01

    Regional hydrological models are important tools in water resources management, but prediction uncertainties are often high due to non-uniqueness of the hydrostratigraphical model. This model is often based on borehole lithology only. However, a much better resolution can be obtained from large geophysical datasets covering the entire domain. Using boreholes to link between hydrostratigraphical classes and resistivity is efficient and emphasizes the need for an all-inclusive data interpretation procedure that can be integrated in groundwater model calibration. We present an automatic method for parameterization of a 3D model of the subsurface, integrating lithological information from boreholes with resistivity models. The objective is to create a direct input to regional groundwater models for sedimentary areas, where the sand/clay distribution governs the groundwater flow. The resistivity input is all-inclusive in the sense that we include data from a variety of instruments (DC and EM, ground-based and airborne), with a varying spatial density and varying ages and quality. The coupling between hydrological and geophysical parameters is managed using a translator function with spatially variable parameters, which is calibrated against observed lithological data. In other words, the translator function interprets the geophysical resistivities into a 3D clay fraction model and the 3D clay fraction model is then turned into a zonation for the hydrological model by a K-means clustering. We present the methodology by show-casing a study from Denmark were a regional groundwater model is constructed by including lithological information from 3100 boreholes over an 710 sqkm area. The geophysical models spans more than 30 years of data collection and includes approx. 225,000 DC models, and 35,000 EM models, airborne as well as groundbased. The final model was calibrated giving parameters that were comparable with existing models based on thorough and time-consuming manual

  19. AfricaArray International Geophysics Field School: Applications of Near Surface Geophysics to challenges encountered in mine planning

    NASA Astrophysics Data System (ADS)

    Webb, S. J.; Jones, M. Q.; Durrheim, R. J.; Nyblade, A.; Snyman, Q.

    2012-12-01

    Hard rock exploration and mining presents many opportunities for the effective use of near surface geophysics. For over 10 years the AfricaArray international geophysics field school has been hosted at a variety of mines in South Africa. While the main objective of the field school is practical training for the next generation of geophysicists, being hosted at a mine has allowed us to investigate applications of near surface geophysics in the early stages of mine planning and development as geophysics is often cheaper and faster than drilling. Several applications include: detailed delineation of dykes and stringer dykes, physical property measurements on drill core for modeling and marker horizons, determination of overburden thickness, locations of water and faults. Dolerite dykes are usually magnetic and are associated with loss of ground (i.e. where the dyke replaces the ore and thus reduces the amount of ore available) and safety/stability concerns. Thus the accurate mapping of dykes and narrow stringers that are associated with them are crucial to the safe planning of a mine. We have acquired several case studies where ground magnetic surveys have greatly improved on the resolution and detail of airborne magnetic surveys in regions of complicated dyke swarms. In many cases, thin stringer dykes of less than 5 cm have been detected. Physical property measurements of these dykes can be used to distinguish between different ages of dykes. It is important to accurately determine overburden thickness when planning an open pit mine as this directly affects the cost of development. Depending on the nature of the overburden, both refraction seismic and or DC resistivity can provide continuous profiling in the area of interest that fills in gaps between boreholes. DC resistivity is also effective for determining water associated with dykes and structures that may affect mine planning. The field school mainly addresses the training of a variety of students. The core

  20. Characterization of aquifer heterogeneity using Cyclostratigraphy and geophysical methods in the upper part of the Karstic Biscayne Aquifer, Southeastern Florida

    USGS Publications Warehouse

    Cunningham, Kevin J.; Carlson, Janine L.; Wingard, G. Lynn; Robinson, Edward; Wacker, Michael A.

    2004-01-01

    This report identifies and characterizes candidate ground-water flow zones in the upper part of the shallow, eogenetic karst limestone of the Biscayne aquifer in the Lake Belt area of north-central Miami-Dade County using cyclostratigraphy, ground-penetrating radar (GPR), borehole geophysical logs, and continuously drilled cores. About 60 miles of GPR profiles were used to calculate depths to shallow geologic contacts and hydrogeologic units, image karst features, and produce qualitative views of the porosity distribution. Descriptions of the lithology, rock fabrics, and cyclostratigraphy, and interpretation of depositional environments of 50 test coreholes were linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Molluscan and benthic foraminiferal paleontologic constraints guided interpretation of depositional environments represented by rockfabric facies. Digital borehole images were used to characterize and quantify large-scale vuggy porosity. Preliminary heat-pulse flowmeter data were coupled with the digital borehole image data to identify candidate ground-water flow zones. Combined results show that the porosity and permeability of the karst limestone of the Biscayne aquifer have a highly heterogeneous and anisotropic distribution that is mostly related to secondary porosity overprinting vertical stacking of rock-fabric facies within high-frequency cycles (HFCs). This distribution of porosity produces a dual-porosity system consisting of diffuse-carbonate and conduit flow zones. The nonuniform ground-water flow in the upper part of the Biscayne aquifer is mostly localized through secondary permeability, the result of solution-enlarged carbonate grains, depositional textures, bedding planes, cracks, root molds, and paleokarst surfaces. Many of the resulting pore types are classified as touching vugs. GPR, borehole geophysical logs, and whole-core analyses show that there is an empirical relation between formation porosity

  1. Successful educational geophysics field program expands

    NASA Astrophysics Data System (ADS)

    The Summer of Applied Geophysical Experience (SAGE), a program that gives students an opportunity to apply a variety of modern geophysical methods in a challenging geologic environment, has expanded.A 2-year grant awarded in 1993 by the National Science Foundation's Research Experiences for Undergraduate's (REU) initiative allowed the program to include fourteen U.S. undergraduate students last summer.

  2. Agricultural Geophysics: Past, present, and future

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Geophysical methods are becoming an increasingly valuable tool for agricultural applications. Agricultural geophysics investigations are commonly (although certainly not always) focused on delineating small- and/or large-scale objects/features within the soil profile (~ 0 to 2 m depth) over very lar...

  3. About the effectiveness of the ABPD methods in air-borne alpha-activity monitoring.

    PubMed

    Shevchenko, S V; Saltykov, L S; Slusarenko, L I

    2006-01-01

    A modified version of the alpha-beta-pseudo-coincidence-difference (ABPD-M) method is proposed with a view to suppressing natural background radiation when measuring the transuranium radionuclide (TRU) content in aerosol samples. It is shown that complementing the traditional "pseudo-coincidence" method with a treatment of (comparatively) fast beta-alpha coincidences provides a means to significantly improve the suppression of background fluctuations and the accuracy of measurement results in comparison with the traditional method.

  4. Comparison of direct and indirect methods of measuring airborne chrysotile fibre concentration.

    PubMed

    Eypert-Blaison, Celine; Veissiere, Sylvie; Rastoix, Olivier; Kauffer, Edmond

    2010-01-01

    Transmission electron microscopy observations most frequently form a basis for estimating asbestos fibre concentration in the environment and in buildings with asbestos-containing materials. Sampled fibres can be transferred to microscope grids by applying either a direct [ISO (1995) Draft International ISO/DIS 10312. Ambient air. Determination of asbestos fibres. Direct transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] or an indirect [AFNOR (1996) Détermination de la concentration en fibres d'amiante par microscopie électronique à transmission-Méthode indirecte. Cedex, France: AFNOR, p. 42; ISO (1997) Draft International ISO/DIS 13794. Ambient air. Determination of asbestos fibres. Indirect-transfer transmission electron microscopy procedure. Geneva, Switzerland: International Standardization Organization] method. In the latter case, ISO Standard 13794 recommends filtering calcination residues either on a polycarbonate (PC) filter (PC indirect method) or on a cellulose ester (CE) membrane (CE indirect method). The PC indirect method requires that fibres deposited on a PC filter be covered by a carbon layer, whereas in the CE indirect method, the CE membrane has to be directly processed using a method described in ISO Standard 10312. The purpose of this study was to compare results obtained using, on the one hand, direct preparation methods and, on the other hand, PC indirect or CE indirect methods, for counting asbestos fibres deposited on filters as a result of liquid filtration or air sampling. In direct method-based preparation, we observed that an etching time of 6-14 min does not affect the measured densities, except for fibres <1 microm deposited by liquid filtration. Moreover, in all cases, the direct method gives higher densities than the PC indirect method because of possible fibre disappearance when using the carbon evaporator implemented in the PC indirect method. The CE membrane

  5. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carlo Methods: A Case Study at the South Oyster Bacterial Transport Site in Virginia

    SciTech Connect

    Chen, Jinsong; Hubbard, Susan; Rubin, Yoram; Murray, Christopher J.; Roden, Eric E.; Majer, Ernest L.

    2004-12-22

    The paper demonstrates the use of ground-penetrating radar (GPR) tomographic data for estimating extractable Fe(II) and Fe(III) concentrations using a Markov chain Monte Carlo (MCMC) approach, based on data collected at the DOE South Oyster Bacterial Transport Site in Virginia. Analysis of multidimensional data including physical, geophysical, geochemical, and hydrogeological measurements collected at the site shows that GPR attenuation and lithofacies are most informative for the estimation. A statistical model is developed for integrating the GPR attenuation and lithofacies data. In the model, lithofacies is considered as a spatially correlated random variable and petrophysical models for linking GPR attenuation to geochemical parameters were derived from data at and near boreholes. Extractable Fe(II) and Fe(III) concentrations at each pixel between boreholes are estimated by conditioning to the co-located GPR data and the lithofacies measurements along boreholes through spatial correlation. Cross-validation results show that geophysical data, constrained by lithofacies, provided information about extractable Fe(II) and Fe(III) concentration in a minimally invasive manner and with a resolution unparalleled by other geochemical characterization methods. The developed model is effective and flexible, and should be applicable for estimating other geochemical parameters at other sites.

  6. INEL cold test pit demonstration of improvements in information derived from non-intrusive geophysical methods over buried waste sites. Phase 1, Final report

    SciTech Connect

    Not Available

    1993-09-08

    The objectives of this research project were to lay the foundation for further improvement in the use of geophysical methods for detection of buried wastes, and to increase the information content derived from surveys. Also, an important goal was to move from mere detection to characterization of buried wastes. The technical approach to achieve these objectives consisted of: (1) Collect a data set of high spatial density; (2) Acquire data with multiple sensors and integrate the interpretations inferred from the various sensors; (3) Test a simplified time domain electromagnetic system; and (4) Develop imaging and display formats of geophysical data readily understood by environmental scientists and engineers. The breadth of application of this work is far reaching. Not only are uncontrolled waste pits and trenches, abandoned underground storage tanks, and pipelines found throughout most US DOE facilities, but also at military installations and industrial facilities. Moreover, controlled land disposal sites may contain ``hot spots`` where drums and hazardous material may have been buried. The technologies addressed by the R&D will benefit all of these activities.

  7. Results of study of deep underground structure of mud volcanoes in North-Western Caucasus by means of geological and geophysical methods

    NASA Astrophysics Data System (ADS)

    Sobissevitch, A. L.; Gorbatikov, A. V.; Ovsuychenko, A. N.; Sobissevitch, L. E.; Stepanova, M. Yu.; Morev, B. A.

    2009-04-01

    Results of complementary geological and geophysical studies of mud volcanic phenomena in North-Western Caucasus (Taman mud volcanic province) are presented. New technology for passive subsurface sounding of the Earth's crust has been originally developed at the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Patented since 2005, this technology represents the new kind of seismic survey based on specific features of propagation of the Rayleigh waves. It uses natural background microseismic noise as a sounding signal. By using the method of low-frequency microseismic sounding in the course of field works carried out in 2006 - 2008, there have been obtained three vertical cross-sections for the two mud volcanoes down to the depth of 25 km. For the two different mud volcanoes their deep subsurface structure has been revealed and discussed. The Gora Karabetova mud volcano is one of the most active mud volcanoes in the Taman peninsula with primarily explosive behaviour while the Shugo mud volcano's activity pattern is different, explosive events are rare and both types of phenomena may be explained by the configuration of their feeding systems, tectonic position and deep pathways of migration of fluids. Complementary interpretation of raw data sets delivered form geophysical and geological surveys allows considering principal differences of origin and mechanisms of mud volcanic activity for the Shugo and the Gora Karabetova mud volcanoes.

  8. Automated method for simultaneous lead and strontium isotopic analysis applied to rainwater samples and airborne particulate filters (PM10).

    PubMed

    Beltrán, Blanca; Avivar, Jessica; Mola, Montserrat; Ferrer, Laura; Cerdà, Víctor; Leal, Luz O

    2013-09-03

    A new automated, sensitive, and fast system for the simultaneous online isolation and preconcentration of lead and strontium by sorption on a microcolumn packed with Sr-resin using an inductively coupled plasma mass spectrometry (ICP-MS) detector was developed, hyphenating lab-on-valve (LOV) and multisyringe flow injection analysis (MSFIA). Pb and Sr are directly retained on the sorbent column and eluted with a solution of 0.05 mol L(-1) ammonium oxalate. The detection limits achieved were 0.04 ng for lead and 0.03 ng for strontium. Mass calibration curves were used since the proposed system allows the use of different sample volumes for preconcentration. Mass linear working ranges were between 0.13 and 50 ng and 0.1 and 50 ng for lead and strontium, respectively. The repeatability of the method, expressed as RSD, was 2.1% and 2.7% for Pb and Sr, respectively. Environmental samples such as rainwater and airborne particulate (PM10) filters as well as a certified reference material SLRS-4 (river water) were satisfactorily analyzed obtaining recoveries between 90 and 110% for both elements. The main features of the LOV-MSFIA-ICP-MS system proposed are the capability to renew solid phase extraction at will in a fully automated way, the remarkable stability of the column which can be reused up to 160 times, and the potential to perform isotopic analysis.

  9. Assessing the performance of methods to detect and quantify African dust in airborne particulates.

    PubMed

    Viana, Mar; Salvador, Pedro; Artíñano, Begoña; Querol, Xavier; Alastuey, Andrés; Pey, Jorge; Latz, Achim J; Cabañas, Mercè; Moreno, Teresa; García dos Santos, Saúl; Herce, María Dolores; Diez Hernández, Pablo; Romero García, Dolores; Fernández-Patier, Rosalía

    2010-12-01

    African dust (AD) contributions to particulate matter (PM) levels may be reported by Member States to the European Commission during justification of exceedances of the daily limit value (DLV). However, the detection and subsequent quantification of the AD contribution to PM levels is complex, and only two measurement-based methods are available in the literature: the Spanish-Portuguese reference method (SPR), and the Tel Aviv University method (TAU). In the present study, both methods were assessed. The SPR method was more conservative in the detection of episodes (71 days identified as AD by SPR, vs 81 by TAU), as it is less affected by interferences with local dust sources. The mean annual contribution of AD was lower with the TAU method than with SPR (2.7 vs 3.5 ± 1.5 μg/m(3)). The SPR and TAU AD time series were correlated with daily aluminum levels (a known tracer of AD), as well as with an AD source identified by the Positive Matrix Factorization (PMF) receptor model. Higher r(2) values were obtained with the SPR method than with TAU in both cases (r(2) = 0.72 vs 0.56, y = 0.05x vs y = 0.06x with aluminum levels; r(2)=0.79 vs 0.43, y = 0.8x vs y = 0.4x with the PMF source). We conclude that the SPR method is more adequate from an EU policy perspective (justification of DLV exceedances) due to the fact that it is more conservative than the TAU method. Based on our results, the TAU method requires adaptation of the thresholds in the algorithm to refine detection of low-impact episodes and avoid misclassification of local events as AD.

  10. Global Estimates of Fine Particulate Matter Using a Combined Geophysical-Statistical Method with Information from Satellites, Models, and Monitors

    NASA Technical Reports Server (NTRS)

    Van Donkelaar, Aaron; Martin, Randall V.; Brauer, Michael; Hsu, N. Christina; Kahn, Ralph A.; Levy, Robert C.; Lyapustin, Alexei; Sayer, Andrew M.; Winker, David M.

    2016-01-01

    We estimated global fine particulate matter (PM(sub 2.5)) concentrations using information from satellite-, simulation- and monitor-based sources by applying a Geographically Weighted Regression (GWR) to global geophysically-based satellite-derived PM(sub 2.5) estimates. Aerosol optical depth from multiple satellite products (MISR, MODIS Dark Target, MODIS and SeaWiFS Deep Blue, and MODIS MAIAC) was combined with simulation (GEOS-Chem) based upon their relative uncertainties as determined using ground-based sun photometer (AERONET) observations for 1998-2014. The GWR predictors included simulated aerosol composition and land use information. The resultant PM(sub 2.5) estimates were highly consistent (R(sup 2) equals 0.81) with out-of-sample cross-validated PM(sub 2.5) concentrations from monitors. The global population-weighted annual average PM(sub 2.5) concentrations were 3-fold higher than the 10 micrograms per cubic meter WHO guideline, driven by exposures in Asian and African regions. Estimates in regions with high contributions from mineral dust were associated with higher uncertainty, resulting from both sparse ground-based monitoring, and challenging conditions for retrieval and simulation. This approach demonstrates that the addition of even sparse ground-based measurements to more globally continuous PM(sub 2.5) data sources can yield valuable improvements to PM(sub 2.5) characterization on a global scale.

  11. Geophysical monitoring of simulated clandestine graves using electrical and ground-penetrating radar methods: 0-3 years after burial.

    PubMed

    Pringle, Jamie K; Jervis, John R; Hansen, James D; Jones, Glenda M; Cassidy, Nigel J; Cassella, John P

    2012-11-01

    This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated "wrapped" and "naked" burials were created. Multigeophysical surveys were collected over a 3-year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground-penetrating radar (GPR), and grave and background "soil-water" conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low-resistivity anomalies, whereas the wrapped burial had small, varying high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed the wrapped burial could be detected throughout, with the "naked" burial mostly resolved. Two hundred and twenty-five megahertz frequency GPR data were optimal. "Soil-water" analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target "wrapping" is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay-rich soils.

  12. Global Estimates of Fine Particulate Matter using a Combined Geophysical-Statistical Method with Information from Satellites, Models, and Monitors.

    PubMed

    van Donkelaar, Aaron; Martin, Randall V; Brauer, Michael; Hsu, N Christina; Kahn, Ralph A; Levy, Robert C; Lyapustin, Alexei; Sayer, Andrew M; Winker, David M

    2016-04-05

    We estimated global fine particulate matter (PM2.5) concentrations using information from satellite-, simulation- and monitor-based sources by applying a Geographically Weighted Regression (GWR) to global geophysically based satellite-derived PM2.5 estimates. Aerosol optical depth from multiple satellite products (MISR, MODIS Dark Target, MODIS and SeaWiFS Deep Blue, and MODIS MAIAC) was combined with simulation (GEOS-Chem) based upon their relative uncertainties as determined using ground-based sun photometer (AERONET) observations for 1998-2014. The GWR predictors included simulated aerosol composition and land use information. The resultant PM2.5 estimates were highly consistent (R(2) = 0.81) with out-of-sample cross-validated PM2.5 concentrations from monitors. The global population-weighted annual average PM2.5 concentrations were 3-fold higher than the 10 μg/m(3) WHO guideline, driven by exposures in Asian and African regions. Estimates in regions with high contributions from mineral dust were associated with higher uncertainty, resulting from both sparse ground-based monitoring, and challenging conditions for retrieval and simulation. This approach demonstrates that the addition of even sparse ground-based measurements to more globally continuous PM2.5 data sources can yield valuable improvements to PM2.5 characterization on a global scale.

  13. Formal methods and their role in digital systems validation for airborne systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1995-01-01

    This report is based on one prepared as a chapter for the FAA Digital Systems Validation Handbook (a guide to assist FAA certification specialists with advanced technology issues). Its purpose is to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used in critical applications; and to suggest factors for consideration when formal methods are offered in support of certification. The presentation concentrates on the rationale for formal methods and on their contribution to assurance for critical applications within a context such as that provided by DO-178B (the guidelines for software used on board civil aircraft); it is intended as an introduction for those to whom these topics are new.

  14. Fiber optic geophysical sensors

    DOEpatents

    Homuth, Emil F.

    1991-01-01

    A fiber optic geophysical sensor in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects.

  15. COMPARISON OF METHODS FOR DETECTION AND ENUMERATION OF AIRBORNE MICROORGANISMS COLLECTED BY LIQUID IMPINGEMENT

    EPA Science Inventory

    Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentratio...

  16. Tillandsia stricta Sol (Bromeliaceae) leaves as monitors of airborne particulate matter-A comparative SEM methods evaluation: Unveiling an accurate and odd HP-SEM method.

    PubMed

    de Oliveira, Martha Lima; de Melo, Edésio José Tenório; Miguens, Flávio Costa

    2016-09-01

    Airborne particulate matter (PM) has been included among the most important air pollutants by governmental environment agencies and academy researchers. The use of terrestrial plants for monitoring PM has been widely accepted, particularly when it is coupled with SEM/EDS. Herein, Tillandsia stricta leaves were used as monitors of PM, focusing on a comparative evaluation of Environmental SEM (ESEM) and High-Pressure SEM (HPSEM). In addition, specimens air-dried at formaldehyde atmosphere (AD/FA) were introduced as an SEM procedure. Hydrated specimen observation by ESEM was the best way to get information from T. stricta leaves. If any artifacts were introduced by AD/FA, they were indiscernible from those caused by CPD. Leaf anatomy was always well preserved. PM density was determined on adaxial and abaxial leaf epidermis for each of the SEM proceedings. When compared with ESEM, particle extraction varied from 0 to 20% in air-dried leaves while 23-78% of particles deposited on leaves surfaces were extracted by CPD procedures. ESEM was obviously the best choice over other methods but morphological artifacts increased in function of operation time while HPSEM operation time was without limit. AD/FA avoided the shrinkage observed in the air-dried leaves and particle extraction was low when compared with CPD. Structural and particle density results suggest AD/FA as an important methodological approach to air pollution biomonitoring that can be widely used in all electron microscopy labs. Otherwise, previous PM assessments using terrestrial plants as biomonitors and performed by conventional SEM could have underestimated airborne particulate matter concentration.

  17. The examination of the spread of the leachates coming out of a solid waste disposal area on the ground with geophysical and geochemical methods (Sivas, Turkey)

    NASA Astrophysics Data System (ADS)

    Özel, Sevda; Yılmaz, Ali; Emin Candansayar, M.

    2017-03-01

    This study has been conducted in the irregular solid waste disposal area in the city of Sivas. The pollution spread formed by the leachates coming out of the disposal area has been examined with geophysical and geochemical works in this study. For this reason, the spread of the leachate pollution expanding in different geological units at both sides of a creek on the ground has been examined. For this purpose, the pollution spread has been examined with the methods of Direct Current Resistivity (DCR) and Electromagnetic Conductivity (EMC) and soil analyses. In the DCR method, 2D inversion of each sounding-profile datum measured alongside the lines parallel to each other and 3D inversion of the data measured in all the lines have been used in the interpretations. Apparent conductivity map has been attained from EMC measurements. The results of heavy metal analyses in the soil samples taken alongside the Haçin Creek have been assessed with the Spider diagram method. It has been determined that the flow of the leachate from geophysical models is in a SE direction and towards Kızılırmak and it continues vertically deeper than 4 m. In addition, it has been understood that the flow direction of the leachate is inspected by the geological structures. It has been understood from the geochemical results that the pollution in the soil stems from the leachate. In this way, it has been observed that the underground and surface water resources in the territory are under the threat of the pollution occurring due to the leachate.

  18. Application of near surface geophysical methods to image water table response in an Alpine Meadow, Northern California.

    NASA Astrophysics Data System (ADS)

    Ayers, M.; Blacic, T. M.; Craig, M. S.; Yarnell, S. M.

    2015-12-01

    Meadows are recognized for their value to the ecological, hydrologic, and aesthetic functions of a watershed. As natural water retention sinks, meadows attenuate floods, improve water quality and support herbaceous vegetation that stabilize streambanks and promote high biodiversity. Alpine meadows are especially vital, serving as freshwater sources and distributing to lower lying provinces through ground and surface water interaction. These complexes are highly vulnerable to drought conditions, altered seasonal precipitation patterns, and mismanaged land use. One such location, Van Norden meadow located in the Donner Summit area west of Lake Tahoe, is one of the largest sub-alpine meadows in the Sierra Nevada mountain range of Northern California. Van Norden meadow offers a natural hydrologic laboratory. Ownership transfer of the area from a local land trust to the Forestry Service requires restoration toward natural meadow conditions, and involves notching the dam in 2016 to reduce currently impounded water volumes from 250 to less than 50 acre-feet. To monitor the effects of notching the dam on the upstream meadow conditions, better understanding of the surface and groundwater hydrology both pre-and post-base level alteration is required. Comprehensive understanding of groundwater flux that supports meadow reaches relies on knowledge of their often complex stratigraphic and structural subsurface framework. In recent years hydrogeophysics has emphasized the combination of near surface geophysical techniques, collaborated with well and borehole measures, to qualitatively define these parameters. Building on a preliminary GPR investigation conducted in 2014, in which 44 270 MHz transect lines were collected, we returned to Van Norden meadow in late summer 2015 to collect lower frequency GPR (50 and 100 MHz) and electrical resistivity profiles to better define the groundwater table, sedimentary, and structural features of the meadow.

  19. The impact of particle size selective sampling methods on occupational assessment of airborne beryllium particulates.

    PubMed

    Sleeth, Darrah K

    2013-05-01

    In 2010, the American Conference of Governmental Industrial Hygienists (ACGIH) formally changed its Threshold Limit Value (TLV) for beryllium from a 'total' particulate sample to an inhalable particulate sample. This change may have important implications for workplace air sampling of beryllium. A history of particle size-selective sampling methods, with a special focus on beryllium, will be provided. The current state of the science on inhalable sampling will also be presented, including a look to the future at what new methods or technology may be on the horizon. This includes new sampling criteria focused on particle deposition in the lung, proposed changes to the existing inhalable convention, as well as how the issues facing beryllium sampling may help drive other changes in sampling technology.

  20. Quantifying greenhouse gas emissions from coal fires using airborne and ground-based methods

    USGS Publications Warehouse

    Engle, M.A.; Radke, L.F.; Heffern, E.L.; O'Keefe, J. M. K.; Smeltzer, C.D.; Hower, J.C.; Hower, J.M.; Prakash, A.; Kolker, A.; Eatwell, R.J.; ter, Schure A.; Queen, G.; Aggen, K.L.; Stracher, G.B.; Henke, K.R.; Olea, R.A.; Roman-Colon, Y.

    2011-01-01

    Coal fires occur in all coal-bearing regions of the world and number, conservatively, in the thousands. These fires emit a variety of compounds including greenhouse gases. However, the magnitude of the contribution of combustion gases from coal fires to the environment is highly uncertain, because adequate data and methods for assessing emissions are lacking. This study demonstrates the ability to estimate CO2 and CH4 emissions for the Welch Ranch coal fire, Powder River Basin, Wyoming, USA, using two independent methods: (a) heat flux calculated from aerial thermal infrared imaging (3.7-4.4td-1 of CO2 equivalent emissions) and (b) direct, ground-based measurements (7.3-9.5td-1 of CO2 equivalent emissions). Both approaches offer the potential for conducting inventories of coal fires to assess their gas emissions and to evaluate and prioritize fires for mitigation. ?? 2011.

  1. A simultaneous charge and size measurement method for individual airborne particles using digital holographic particle imaging

    NASA Astrophysics Data System (ADS)

    Hammond, Adam; Dou, Zhongwang; Liang, Zach; Meng, Hui

    2016-11-01

    Recently, significant inquiry to understand the effects of particle charge on particle laden flow have been made, particularly in the study of Lagrangian particle-pair statistics. Quantification of individual particle charge allows relation of inter-particle electric forces and turbulence-induced forces. Here we offer a simultaneous, individual particle charge and size measurement technique utilizing in-line digital holographic Particle Tracking Velocimetry (hPTV). The method measures particle electric mobility through its velocity response within a uniform electric field using a sequence of holograms, next the particle diameter is measured with the same holograms using a matched-filter developed by Lu et al. (2012) as an input for calculation of charge. Consequently, a benefit of this method is that particle charge is calculated on the individual level, versus a mean charge calculated from a group of particles, offering improved estimations of charge distributions for studies of particle laden flow. This work was supported by NSF CBET-0967407 and CBET-0967349.

  2. Comparison of Methods to Map and Measure River Terraces using High-Resolution Airborne LiDAR Data

    NASA Astrophysics Data System (ADS)

    Hopkins, A. J.; Snyder, N. P.

    2013-12-01

    Fluvial terraces are important recorders of land-use, climate, and tectonic history that form in both erosional and depositional landscapes and consist of a flat surface bounded by valley walls and a steep-sloping scarp adjacent to the river channel. Combining these defining characteristics with high-resolution digital elevation models (DEMs) derived from airborne light detection and ranging (lidar) surveys, several methods have been developed to identify and map terraces. The goals of this research are to compare some of these existing techniques and develop an objective approach to map terraces over entire watersheds using lidar DEMs. Additionally, we aim to quantify the thickness and volume of fill terrace deposits. Our preliminary application is to the Sheepscot River watershed, Maine, where strath and fill terraces are present and record Pleistocene deglaciation, Holocene eustatic forcing, and Anthropocene land-use change. We identify terraces along the longitudinal profile using an algorithm developed by Finnegan and Balco (2013), that computes the elevation frequency distribution at regularly spaced cross-sections normal to the channel. Next, we delineate terrace spatial extent using three separate methodologies: (1) image processing using Matlab, (2) feature classification algorithms developed by Wood (1996), and (3) image interpretation using manually placed points on known terraces to construct interpolated surfaces (Walter and Merritts, 2008). Lastly, we determine the thickness and volume of fill terrace sediments by subtracting an interpolated, adjacent water surface elevation from the defined terrace points. We compare our LiDAR-based results with field mapping, stratigraphic columns of terrace landforms, and ground penetrating radar over terrace surfaces. These findings suggest powerful new ways to rapidly analyze landscape history over large regions using high-resolution lidar DEMs, with less reliance on detailed and costly field data collection.

  3. Mapping permafrost with airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  4. Geohydrologic assessment of fractured crystalline bedrock on the southern part of Manhattan, New York, through the use of advanced borehole geophysical methods

    NASA Astrophysics Data System (ADS)

    Stumm, F.; Chu, A.; Joesten, P. K.; Lane, J. W., Jr.

    2007-09-01

    Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, NY in preparation of the construction of a new water tunnel. The study area is located in a highly urbanized part of New York City. The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an overall southwest-to northwest-dipping foliation. Most of the fractures intersected are nearly horizontal or have moderate- to high-angle northwest or eastward dip azimuths. Heat-pulse flowmeter logs obtained under nonpumping (ambient) and pumping conditions, together with other geophysical logs, delineated transmissive fracture zones in each borehole. Water-level and flowmeter data suggest the fractured-rock ground-water-flow system is interconnected. The 60 MHz directional borehole-radar logs delineated the location and orientation of several radar reflectors that did not intersect the projection of the borehole. A total of 53 faults intersected by the boreholes have mean orientation populations of N12°W, 66°W and N11°W, 70°E. A total of 77 transmissive fractures delineated using the heat-pulse flowmeter have mean orientations of N11°E, 14°SE (majority) and N23°E, 57°NW (minority). The transmissivity of the bedrock boreholes ranged from 0.7 to 870 feet squared (ft2) per day (0.07 to 81 metres squared (m2) per day).

  5. Novel method for estimation of the indoor-to-outdoor airborne radioactivity ratio following the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Tan, Yanliang; Ishikawa, Tetsuo; Janik, Miroslaw; Tokonami, Shinji; Hosoda, Masahiro; Sorimachi, Atsuyuki; Kearfott, Kimberlee

    2015-12-01

    The accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan resulted in significant releases of fission products. While substantial data exist concerning outdoor air radioactivity following the accident, the resulting indoor radioactivity remains pure speculation without a proper method for estimating the ratio of the indoor to outdoor airborne radioactivity, termed the airborne sheltering factor (ASF). Lacking a meaningful value of the ASF, it is difficult to assess the inhalation doses to residents and evacuees even when outdoor radionuclide concentrations are available. A simple model was developed and the key parameters needed to estimate the ASF were obtained through data fitting of selected indoor and outdoor airborne radioactivity measurement data obtained following the accident at a single location. Using the new model with values of the air exchange rate, interior air volume, and the inner surface area of the dwellings, the ASF can be estimated for a variety of dwelling types. Assessment of the inhalation dose to individuals readily follows from the value of the ASF, the person's indoor occupancy factor, and the measured outdoor radioactivity concentration.

  6. Comparison of four methods of aerodynamic roughness length parameterization in semi-arid shrublands with airborne LiDAR, hyperspectral, and meteorological data

    NASA Astrophysics Data System (ADS)

    Li, A.; Mitchell, J. J.; Glenn, N. F.; Zhao, W.; Germino, M. J.; Allen, R.; Sankey, J. B.

    2013-12-01

    The aerodynamic roughness length (z0) plays an important role in the flux exchange between the land surface and atmosphere. Especially in semiarid shrublands, z0 is a key parameter for physical models of aeolian transport. z0 is influenced by the height, geometry, density and pattern of roughness elements. Light detection and ranging (LiDAR) is well suited to measure the vegetation height and has been used to estimate z0 across large areas. In this study, we combined airborne LiDAR, hyperspectral imagery and meteorological measurements to estimate z0, and assessed the ability of airborne LiDAR to estimate z0 over semi-arid shrublands. Airborne LiDAR data was used to derive the height of Wyoming big sagebrush (Artemisia tridentate subsp. wyomingensis) over a study area in the Great Basin, Idaho. Roughness density was related with percent vegetation cover which was estimated by integrating LiDAR and hyperspectral data, both collected in August 2011. Four methods of parameterization of z0 were applied and compared with the vegetation height from LiDAR; roughness from LiDAR and hyperspectral; NDVI and LAI from HyMap; and a geometric approach using meteorological data (e.g. wind speed). Micrometeorological measurements at two eddy covariance sites in the study area were used for validation of parameterized z0. The spatial variability of z0 was analyzed and the relationship with vegetation density was explored. The results demonstrated the potential of using airborne LiDAR data to estimate z0 at a regional scale in semi-arid shrublands. Furthermore, z0 showed a tight relationship with local variance of vegetation height and vegetation density.

  7. The DIGISOIL multi-sensor system: from geophysical measurements to soil properties.

    NASA Astrophysics Data System (ADS)

    Grandjean, Gilles

    2010-05-01

    The purposes of the multidisciplinary DIGISOIL project are the integration and improvement of in situ and proximal measurement technologies for the assessment of soil properties and soil degradation indicators, going from the sensing technologies to their integration and their application in (digital) soil mapping (DSM). In order to assess and prevent soil degradation and to benefit from the different ecological, economical and historical functions of the soil in a sustainable way, high resolution and quantitative maps of soil properties are needed. The core objective of the project is to explore and exploit new capabilities of advanced geophysical technologies for answering this societal demand. To this aim, DIGISOIL addresses four issues covering technological, soil science and economic aspects: (i) the validation of geophysical (in situ, proximal and airborne) technologies and integrated pedo-geophysical inversion techniques (mechanistic data fusion) (ii) the relation between the geophysical parameters and the soil properties, (iii) the integration of the derived soil properties for mapping soil functions and soil threats, (iv) the pre-evaluation, standardisation and sub-industrialization of the proposed methodologies, including technical and economical studies related to the societal demand. With respect to these issues, the preliminary tasks of the DIGISOIL project were to develop, test and validate the most relevant geophysical technologies for mapping soil properties. The different field tests, realized at this time, allow focusing on technological suitable solutions for each of the identified methods: geoelectric, GPR, EMI, seismics, magnetic and hyperspectral. After data acquisition systems, sensor geometry, and advanced data processing techniques have been developed and validated, we present now the solutions for going from such data to soil properties maps.

  8. Geophysical techniques in detection to river embankments - A case study: To locate sites of potential leaks using surface-wave and electrical methods

    USGS Publications Warehouse

    Chen, C.; Liu, J.; Xu, S.; Xia, J.; ,

    2004-01-01

    Geophysical technologies are very effective in environmental, engineering and groundwater applications. Parameters of delineating nature of near-surface materials such as compressional-wave velocity, shear-wave velocity can be obtained using shallow seismic methods. Electric methods are primary approaches for investigating groundwater and detecting leakage. Both of methods are applied to detect embankment in hope of obtaining evidences of the strength and moisture inside the body. A technological experiment has done for detecting and discovering the hidden troubles in the embankment of Yangtze River, Songzi, Hubei, China in 2003. Surface-wave and DC multi-channel array resistivity sounding techniques were used to detect hidden trouble inside and under dike like pipe-seeps. This paper discusses the exploration strategy and the effect of geological characteristics. A practical approach of combining seismic and electric resistivity measurements was applied to locate potential pipe-seeps in embankment in the experiment. The method presents a potential leak factor based on the shear-wave velocity and the resistivity of the medium to evaluate anomalies. An anomaly found in a segment of embankment detected was verified, where occurred a pipe-seep during the 98' flooding.

  9. High temperature geophysical instrumentation

    SciTech Connect

    Hardee, H.C.

    1988-06-01

    The instrumentation development program was to proceed in parallel with scientific research and was driven by the needs of researchers. The development of these instruments has therefore included numerous geophysical field tests, many of which have resulted in the publication of scientific articles. This paper is a brief summary of some of the major geophysical instruments that have been developed and tested under the High Temperature Geophysics Program. These instruments are briefly described and references are given for further detailed information and for scientific papers that have resulted from the use of these instruments. 9 refs., 14 figs.

  10. Fiber optic geophysical sensors

    DOEpatents

    Homuth, E.F.

    1991-03-19

    A fiber optic geophysical sensor is described in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects. 2 figures.

  11. Electromagnetic geophysical observation with controlled source

    NASA Astrophysics Data System (ADS)

    Hachay, Olga; Khachay, Oleg

    2016-04-01

    In the paper the new theoretical and methodical approaches are examined for detailed investigations of the structure and state of the geological medium, and its behavior as a dynamic system in reaction to external man-made influences. To solve this problem it is necessary to use geophysical methods that have sufficient resolution and that are built on more complicated models than layered or layered-block models. One of these methods is the electromagnetic induction frequency-geometrical method with controlled sources. Here we consider new approaches using this method for monitoring rock shock media by means of natural experiments and interpretation of the practical results. That method can be used by oil production in mines, where the same events of non stability can occur. The key ideas of twenty first century geophysics from the point of view of geologist academician A.N. Dmitrievskiy [Dmitrievskiy, 2009] are as follows. "The geophysics of the twenty first century is an understanding that the Earth is a self-developing, self-supporting geo-cybernetic system, in which the role of the driving mechanism is played by the field gradients; the evolution of geological processes is a continuous chain of transformations and the interaction of geophysical fields in the litho- hydro- and atmosphere. The use of geophysical principles of a hierarchical quantum of geophysical space, non-linear effects, and the effects of reradiating geophysical fields will allow the creation of a new geophysics. The research, in which earlier only pure geophysical processes and technologies were considered, nowadays tends to include into consideration geophysical-chemical processes and technologies. This transformation will allow us to solve the problems of forecasting geo-objects and geo-processes in previously unavailable geological-technological conditions." The results obtained allow us to make the following conclusions, according to the key ideas of academician A.N. Dmitrievskiy: the rock

  12. Airborne field strength monitoring

    NASA Astrophysics Data System (ADS)

    Bredemeyer, J.; Kleine-Ostmann, T.; Schrader, T.; Münter, K.; Ritter, J.

    2007-06-01

    In civil and military aviation, ground based navigation aids (NAVAIDS) are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS) increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR) is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000) by the International Civil Aviation Organization (ICAO). One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz), the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA) accelerated method of moments (MoM) using a complex geometric model of the aircraft. First results will be presented in this paper.

  13. Use of airborne gamma-ray spectrometry for kaolin exploration

    NASA Astrophysics Data System (ADS)

    Tourlière, B.; Perrin, J.; Le Berre, P.; Pasquet, J. F.

    2003-08-01

    Airborne gamma-ray spectrometry was used to define targets with kaolin potential in the Armorican Massif of Brittany, France. This exploration method is based on the principle that kaolinite, an aluminosilicate clay mineral constituting kaolin, is formed by the hydrolysis of potash feldspar with the elimination of potassium. Therefore, potassium contrast between favourable host-rock such as a leucogranite and kaolin occurrence is likely a significant pathfinder. As the relationship between the potassium-40 recorded by an airborne gamma-ray spectrometer and total potassium is constant, such data provide us a direct measurement of the potassium content of the ground flown over. Our study tested this by calculating, for each geological unit, the difference between the measured and average potassium content calculated for a given geological formation. The study was based on (i) a recent (1998) high-definition airborne geophysical survey over the Armorican Massif undertaken on behalf of the French Government, and (ii) new geological compilation maps covering the same region. Depleted zones, where the measured potassium is less than the average potassium content calculated target areas with high potential of containing kaolin, provided that the unit was originally rich in potash feldspar. By applying this method to the entire Armorican Massif, it was possible to identify 150 potassium-depleted zones, including 115 that were subjected to rapid field checks and 36 that contained kaolin (21 new discoveries). This method, which is both safe for the environment and easy to use, is therefore a good tool for rapidly defining targets with kaolin potential at a regional scale. The method may also have possibilities in exploring for other types of deposit characterised by an enrichment or depletion in U, K and/or Th.

  14. Multiscale geophysical imaging of the critical zone

    NASA Astrophysics Data System (ADS)

    Parsekian, A. D.; Singha, K.; Minsley, B. J.; Holbrook, W. S.; Slater, L.

    2015-03-01

    Details of Earth's shallow subsurface—a key component of the critical zone (CZ)—are largely obscured because making direct observations with sufficient density to capture natural characteristic spatial variability in physical properties is difficult. Yet this inaccessible region of the CZ is fundamental to processes that support ecosystems, society, and the environment. Geophysical methods provide a means for remotely examining CZ form and function over length scales that span centimeters to kilometers. Here we present a review highlighting the application of geophysical methods to CZ science research questions. In particular, we consider the application of geophysical methods to map the geometry of structural features such as regolith thickness, lithological boundaries, permafrost extent, snow thickness, or shallow root zones. Combined with knowledge of structure, we discuss how geophysical observations are used to understand CZ processes. Fluxes between snow, surface water, and groundwater affect weathering, groundwater resources, and chemical and nutrient exports to rivers. The exchange of gas between soil and the atmosphere have been studied using geophysical methods in wetland areas. Indirect geophysical methods are a natural and necessary complement to direct observations obtained by drilling or field mapping. Direct measurements should be used to calibrate geophysical estimates, which can then be used to extrapolate interpretations over larger areas or to monitor changing processes over time. Advances in geophysical instrumentation and computational approaches for integrating different types of data have great potential to fill gaps in our understanding of the shallow subsurface portion of the CZ and should be integrated where possible in future CZ research.

  15. A global method for identifying dependences between helio-geophysical and biological series by filtering the precedents (outliers)

    NASA Astrophysics Data System (ADS)

    Ozheredov, V. A.; Breus, T. K.; Gurfinkel, Yu. I.; Matveeva, T. A.

    2014-12-01

    A new approach to finding the dependence between heliophysical and meteorological factors and physiological parameters is considered that is based on the preliminary filtering of precedents (outliers). The sought-after dependence is masked by extraneous influences which cannot be taken into account. Therefore, the typically calculated correlation between the external-influence ( x) and physiology ( y) parameters is extremely low and does not allow their interdependence to be conclusively proved. A robust method for removing the precedents (outliers) from the database is proposed that is based on the intelligent sorting of the polynomial curves of possible dependences y( x), followed by filtering out the precedents which are far away from y( x) and optimizing the coefficient of nonlinear correlation between the regular, i.e., remaining, precedents. This optimization problem is shown to be a search for a maximum in the absence of the concept of gradient and requires the use of a genetic algorithm based on the Gray code. The relationships between the various medical and biological parameters and characteristics of the space and terrestrial weather are obtained and verified using the cross-validation method. It is proven that, by filtering out no more than 20% of precedents, it is possible to obtain a nonlinear correlation coefficient of no less than 0.5. A juxtaposition of the proposed method for filtering precedents (outliers) and the least-square method (LSM) for determining the optimal polynomial using multiple independent tests (Monte Carlo method) of models, which are as close as possible to real dependences, has shown that the LSM determination loses much in comparison to the proposed method.

  16. Phillips Laboratory Geophysics Scholar Program

    DTIC Science & Technology

    1993-09-30

    research at Phillips Laboratory . Research sponsored by Air Force Geophysics Laboratory ...Geophysics Laboratory (now the Phillips Laboratory , Geophysics Directorate), United States Air Force for its sponsorship of this research through the Air ...September 1993 Approved for public release; distribution unlimited PHILLIPS LABORATORY Directorate of Geophysics AIR FORCE MATERIEL COMMAND

  17. Geophysics, Remote Sensing, and the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Integrated Field Exercise 2014

    NASA Astrophysics Data System (ADS)

    Sussman, A. J.; Macleod, G.; Labak, P.; Malich, G.; Rowlands, A. P.; Craven, J.; Sweeney, J. J.; Chiappini, M.; Tuckwell, G.; Sankey, P.

    2015-12-01

    The Integrated Field Exercise of 2014 (IFE14) was an event held in the Hashemite Kingdom of Jordan (with concurrent activities in Austria) that tested the operational and technical capabilities of an on-site inspection (OSI) within the CTBT verification regime. During an OSI, up to 40 international inspectors will search an area for evidence of a nuclear explosion. Over 250 experts from ~50 countries were involved in IFE14 (the largest simulation of a real OSI to date) and worked from a number of different directions, such as the Exercise Management and Control Teams (which executed the scenario in which the exercise was played) and those participants performing as members of the Inspection Team (IT). One of the main objectives of IFE14 was to test and integrate Treaty allowed inspection techniques, including a number of geophysical and remote sensing methods. In order to develop a scenario in which the simulated exercise could be carried out, suites of physical features in the IFE14 inspection area were designed and engineered by the Scenario Task Force (STF) that the IT could detect by applying the geophysical and remote sensing inspection technologies, in addition to other techniques allowed by the CTBT. For example, in preparation for IFE14, the STF modeled a seismic triggering event that was provided to the IT to prompt them to detect and localize aftershocks in the vicinity of a possible explosion. Similarly, the STF planted shallow targets such as borehole casings and pipes for detection using other geophysical methods. In addition, airborne technologies, which included multi-spectral imaging, were deployed such that the IT could identify freshly exposed surfaces, imported materials, and other areas that had been subject to modification. This presentation will introduce the CTBT and OSI, explain the IFE14 in terms of the goals specific to geophysical and remote sensing methods, and show how both the preparation for and execution of IFE14 meet those goals.

  18. Geophysical investigation using resistivity and GPR methods: a case study of a lubricant oil waste disposal area in the city of Ribeirão Preto, São Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Lago, Alexandre Lisboa; Elis, Vagner Roberto; Borges, Welitom Rodrigues; Penner, Giovanni Chaves

    2009-07-01

    Geophysics has been shown to be effective in identifying areas contaminated by waste disposal, contributing to the greater efficiency of soundings programs and the installation of monitoring wells. In the study area, four trenches were constructed with a total volume of about 25,000 m3. They were almost totally filled with re-refined lubricating oil waste for approximately 25 years. No protection liners were used in the bottoms and laterals of the disposal trenches. The purpose of this work is to evaluate the potential of the resistivity and ground penetrating radar (GPR) methods in characterizing the contamination of this lubricant oil waste disposal area in Ribeirão Preto, SP, situated on the geological domain of the basalt spills of the Serra Geral Formation and the sandstones of the Botucatu Formation. Geophysical results were shown in 2D profiles. The geophysical methods used enabled the identification of geophysical anomalies, which characterized the contamination produced by the trenches filled with lubricant oil waste. Conductive anomalies (smaller than 185 Ωm) immediately below the trenches suggest the action of bacteria in the hydrocarbons, as has been observed in several sites contaminated by hydrocarbons in previously reported cases in the literature. It was also possible to define the geometry of the trenches, as evidenced by the GPR method. Direct sampling (chemical analysis of the soil and the water in the monitoring well) confirmed the contamination. In the soil analysis, low concentrations of several polycyclic aromatic hydrocarbons (PAHs) were found, mainly naphthalene and phenanthrene. In the water samples, an analysis verified contamination of the groundwater by lead (Pb). The geophysical methods used in the investigation provided an excellent tool for environmental characterization in this study of a lubricant oil waste disposal area, and could be applied in the study of similar areas.

  19. DOMAIN DECOMPOSITION METHOD APPLIED TO A FLOW PROBLEM Norberto C. Vera Guzmán Institute of Geophysics, UNAM

    NASA Astrophysics Data System (ADS)

    Vera, N. C.; GMMC

    2013-05-01

    In this paper we present the results of macrohybrid mixed Darcian flow in porous media in a general three-dimensional domain. The global problem is solved as a set of local subproblems which are posed using a domain decomposition method. Unknown fields of local problems, velocity and pressure are approximated using mixed finite elements. For this application, a general three-dimensional domain is considered which is discretized using tetrahedra. The discrete domain is decomposed into subdomains and reformulated the original problem as a set of subproblems, communicated through their interfaces. To solve this set of subproblems, we use finite element mixed and parallel computing. The parallelization of a problem using this methodology can, in principle, to fully exploit a computer equipment and also provides results in less time, two very important elements in modeling. Referencias G.Alduncin and N.Vera-Guzmán Parallel proximal-point algorithms for mixed _nite element models of _ow in the subsurface, Commun. Numer. Meth. Engng 2004; 20:83-104 (DOI: 10.1002/cnm.647) Z. Chen, G.Huan and Y. Ma Computational Methods for Multiphase Flows in Porous Media, SIAM, Society for Industrial and Applied Mathematics, Philadelphia, 2006. A. Quarteroni and A. Valli, Numerical Approximation of Partial Differential Equations, Springer-Verlag, Berlin, 1994. Brezzi F, Fortin M. Mixed and Hybrid Finite Element Methods. Springer: New York, 1991.

  20. Geophysical Characterization of the Quaternary-Cretaceous Contact Using Surface Resistivity Methods in Franklin and Webster Counties, South-Central Nebraska

    USGS Publications Warehouse

    Teeple, Andrew; Kress, Wade H.; Cannia, James C.; Ball, Lyndsay B.

    2009-01-01

    To help manage and understand the Platte River system in Nebraska, the Platte River Cooperative Hydrology Study (COHYST), a group of state and local governmental agencies, developed a regional ground-water model. The southern boundary of this model lies along the Republican River, where an area with insufficient geologic data immediately north of the Republican River led to problems in the conceptualization of the simulated flow system and to potential problems with calibration of the simulation. Geologic descriptions from a group of test holes drilled in south-central Nebraska during 2001 and 2002 indicated a possible hydrologic disconnection between the Quaternary-age alluvial deposits in the uplands and those in the Republican River lowland. This disconnection was observed near a topographic high in the Cretaceous-age Niobrara Formation, which is the local bedrock. In 2003, the U.S. Geological Survey, in cooperation with the COHYST, collected surface geophysical data near these test holes to better define this discontinuity. Two-dimensional imaging methods for direct-current resistivity and capacitively coupled resistivity were used to define the subsurface distribution of resistivity along several county roads near Riverton and Inavale, Nebraska. The relation between the subsurface distribution of resistivity and geology was defined by comparing existing geologic descriptions of test holes to surface-geophysical resistivity data along two profiles and using the information gained from these comparisons to interpret the remaining four profiles. In all of the resistivity profile sections, there was generally a three-layer subsurface interpretation, with a resistor located between two conductors. Further comparison of geologic data with the geophysical data and with surficial features was used to identify a topographic high in the Niobrara Formation near the Franklin Canal which was coincident with a resistivity high. Electrical properties of the Niobrara

  1. Polarimetric remote sensing of geophysical medium structures

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.; Yueh, S. H.; Kwok, R.; Nguyen, D. T.

    1993-11-01

    Polarimetric remote sensing of structures in geophysical media is studied in this paper based on their symmetry properties. Orientations of spheroidal scatterers described by spherical, uniform, planophile, plagiothile, erectophile, and extremophile distributions are considered to derive their polarimetric backscattering characteristics. These distributions can be identified from the observed scattering coefficients by comparison with theoretical symmetry calculations. A new parameter is defined to study scattering structures in geophysical media. Experimental observations from polarimetric data acquired by the Jet Propulsion Laboratory airborne synthetic aperture radar over forests, sea ice, and sea surface are presented to illustrate the use of symmetry properties. For forests, the coniferous forest in Mount Shasta area and mixed forests near Presque Isle show evidence of the centrical symmetry at C band. In sea ice from the Beaufort Sea, multiyear sea ice has a cross-polarized ratio e close to e0, calculated from symmetry, due to the randomness in the scattering structure. For first-year sea ice, e is much smaller than e0 as a result of preferential alignment of the columnar structure of the ice. From polarimetric data of a sea surface in the Bering sea, it is observed that e and e0 are increasing with incident angle and e is greater than e0 at L band because of the directional feature of sea surface waves. Use of symmetry properties of geophysical media for polarimetric radar calibration is also suggested.

  2. A Field Evaluation of Airborne Techniques for Detection of Unexploded Ordnance

    SciTech Connect

    Bell, D.; Doll, W.E.; Hamlett, P.; Holladay, J.S.; Nyquist, J.E.; Smyre, J.; Gamey, T.J.

    1999-03-14

    US Defense Department estimates indicate that as many as 11 million acres of government land in the U. S. may contain unexploded ordnance (UXO), with the cost of identifying and disposing of this material estimated at nearly $500 billion. The size and character of the ordnance, types of interference, vegetation, geology, and topography vary from site to site. Because of size or composition, some ordnance is difficult to detect with any geophysical method, even under favorable soil and cultural interference conditions. For some sites, airborne methods may provide the most time and cost effective means for detection of UXO. Airborne methods offer lower risk to field crews from proximity to unstable ordnance, and less disturbance of sites that maybe environmentally sensitive. Data were acquired over a test site at Edwards AFB, CA using airborne magnetic, electromagnetic, multispectral and thermal sensors. Survey areas included sites where trenches might occur, and a test site in which we placed deactivated ordnance, ranging in size from small ''bomblets'' to large bombs. Magnetic data were then acquired with the Aerodat HM-3 system, which consists of three cesium magnetometers within booms extending to the front and sides of the helicopter, and mounted such that the helicopter can be flown within 3m of the surface. Electromagnetic data were acquired with an Aerodat 5 frequency coplanar induction system deployed as a sling load from a helicopter, with a sensor altitude of 15m. Surface data, acquired at selected sites, provide a comparison with airborne data. Multispectral and thermal data were acquired with a Daedelus AADS 1268 system. Preliminary analysis of the test data demonstrate the value of airborne systems for UXO detection and provide insight into improvements that might make the systems even more effective.

  3. SAGE (Summer of Applied Geophysical Experience): Learning Geophysics by Doing Geophysics

    NASA Astrophysics Data System (ADS)

    Jiracek, G. R.; Baldridge, W. S.; Biehler, S.; Braile, L. W.; Ferguson, J. F.; Gilpin, B. E.; Pellerin, L.

    2005-12-01

    SAGE, a field-based educational program in applied geophysical methods has been an REU site for 16 years and completed its 23rd year of operation in July 2005. SAGE teaches the major geophysical exploration methods (including seismics, gravity, magnetics, and electromagnetics) and applies them to the solution of specific local and regional geologic problems. These include delineating buried hazardous material; mapping archaeological sites; and studying the structure, tectonics, and water resources of the Rio Grande rift in New Mexico. Nearly 600 graduates, undergraduates, and professionals have attended SAGE since 1983. Since 1990 REU students have numbered 219 coming from dozens of different campuses. There have been 124 underrepresented REU students including 100 women, 14 Hispanics, 7 Native Americans, and 3 African Americans. Tracking of former REU students has revealed that 81% have gone on to graduate school. Keys to the success of SAGE are hands-on immersion in geophysics for one month and a partnership between academia, industry, and a federal laboratory. Successful approaches at SAGE include: 1) application of the latest equipment by all students; 2) continued updating of equipment, computers, and software by organizing universities and industry affiliates; 3) close ties with industry who provide supplemental instruction, furnish new equipment and software, and alert students to the current industry trends and job opportunities; 4) two-team, student data analysis structure that simultaneously addresses specific geophysical techniques and their integration; and 5) oral and written reports patterned after professional meetings and journals. An eight member, 'blue ribbon' advisory panel from academia, industry, and the federal government has been set up to maintain the vitality of SAGE by addressing such issues as funding, new faculty, organization, and vision. SAGE is open to students from any university (or organization) with backgrounds including

  4. Estimating the state of a geophysical system with sparse observations: time delay methods to achieve accurate initial states for prediction

    NASA Astrophysics Data System (ADS)

    An, Zhe; Rey, Daniel; Ye, Jingxin; Abarbanel, Henry D. I.

    2017-01-01

    The problem of forecasting the behavior of a complex dynamical system through analysis of observational time-series data becomes difficult when the system expresses chaotic behavior and the measurements are sparse, in both space and/or time. Despite the fact that this situation is quite typical across many fields, including numerical weather prediction, the issue of whether the available observations are "sufficient" for generating successful forecasts is still not well understood. An analysis by Whartenby et al. (2013) found that in the context of the nonlinear shallow water equations on a β plane, standard nudging techniques require observing approximately 70 % of the full set of state variables. Here we examine the same system using a method introduced by Rey et al. (2014a), which generalizes standard nudging methods to utilize time delayed measurements. We show that in certain circumstances, it provides a sizable reduction in the number of observations required to construct accurate estimates and high-quality predictions. In particular, we find that this estimate of 70 % can be reduced to about 33 % using time delays, and even further if Lagrangian drifter locations are also used as measurements.

  5. Airborne Gravimetry and Downward Continuation (Invited)

    NASA Astrophysics Data System (ADS)

    Jekeli, C.; Yang, H.; Kwon, J.

    2009-12-01

    Measuring the Earth’s gravity field using airborne instrumentation is fully operational and has been widely practiced for nearly three decades since its official debut in the early 1980s (S. Hammer: “Airborne Gravity is Here!”) coinciding with the precision kinematic positioning capability of GPS. Airborne gravimetry is undertaken for both efficient geophysical exploration purposes, as well as the determination of the regional geoid to aid in the modernization of height systems. Especially for the latter application, downward continuation of the data and combination with existing terrestrial gravimetry pose theoretical as well as practical challenges, which, on the other hand, create multiple processing possibilities. Downward continuation may be approached in various ways from the viewpoint of potential theory and the boundary-value problem to using gradients either estimated locally or computed from existing models. Logistical constraints imposed by the airborne survey, instrumental noise, and the intrinsic numerical instability of downward continuation all conspire to impact the final product in terms of achievable resolution and accuracy. In this paper, we review the theory of airborne gravimetry and the methodology of downward continuation, and provide a numerical comparison of possible schemes and their impact on geoid determination.

  6. Measuring Groundwater Storage Potential in Mountain Meadows using Geophysical Methods at Red Clover Meadow Complex, Sierra Nevada, CA

    NASA Astrophysics Data System (ADS)

    Covey, J.; Cornwell, K.

    2014-12-01

    ABSTRACT The Dotta Canyon meadow, located in the Red Clover Meadow complex, upper Feather River Watershed, Plumas County, California, was studied to measure sediment volume and groundwater storage capacity in this mountain meadow environment. Groundwater resources in mountain meadows play an important role in providing baseflow to local stream systems during dry summer months. Degraded meadows reduce baseflow contributions to local streams throughout the year impacting the local flora and fauna and water resources downstream. Groundwater storage potential of meadows is a function of the total volume of meadow sediments, the types of sediment present and the effective porosity of those materials. Assessing these properties in meadows is difficult though as meadow environments are commonly sensitive to investigative disturbances like drill rigs and backhoes. We applied seismic refraction techniques to measure the thickness of meadow sediments in the 8.3 km2 Dotta Canyon. Specifically we conducted 42 seismic surveys, utilizing forward and reverse profiles to create a depth to bedrock isopach map of the Dotta Canyon meadow. Using ArcGIS software, aerial photographs and field GPS data to measure and calculate the meadow area and limited hand augering, we were able to calculate the volume of sediment in the meadow to be about 2.5E7 cubic meters. Hand augering in the meadow produced a record of meadow stratigraphy and helped determine appropriate locations for the collection of representative core samples. Representative cores were processed for effective porosity using the water porosimetry method. A mean effective porosity of 38%.was applied to volumetric calculations with results suggesting a groundwater storage capacity of 9.4E6 cubic meters.

  7. Site characterization at the Rabbit Valley Geophysical Performance Evaluation Range

    SciTech Connect

    Koppenjan, S,; Martinez, M.

    1994-06-01

    The United States Department of Energy (US DOE) is developing a Geophysical Performance Evaluation Range (GPER) at Rabbit Valley located 30 miles west of Grand Junction, Colorado. The purpose of the range is to provide a test area for geophysical instruments and survey procedures. Assessment of equipment accuracy and resolution is accomplished through the use of static and dynamic physical models. These models include targets with fixed configurations and targets that can be re-configured to simulate specific specifications. Initial testing (1991) combined with the current tests at the Rabbit Valley GPER will establish baseline data and will provide performance criteria for the development of geophysical technologies and techniques. The US DOE`s Special Technologies Laboratory (STL) staff has conducted a Ground Penetrating Radar (GPR) survey of the site with its stepped FM-CW GPR. Additionally, STL contracted several other geophysical tests. These include an airborne GPR survey incorporating a ``chirped`` FM-CW GPR system and a magnetic survey with a surfaced-towed magnetometer array unit Ground-based and aerial video and still frame pictures were also acquired. STL compiled and analyzed all of the geophysical maps and created a site characterization database. This paper discusses the results of the multi-sensor geophysical studies performed at Rabbit Valley and the future plans for the site.

  8. Near-Real-Time Geophysical and Biological Monitoring of Bioremediation Methods at a Uranium Mill Tailings Site in Rifle, Colorado

    NASA Astrophysics Data System (ADS)

    Tarrell, A. N.; Haas, A.; Revil, A.; Figueroa, L. A.; Rodriguez, D.; Smartgeo

    2010-12-01

    network deployed through monitoring wells in the experiment tank and the development of a machine learning classifier to integrate near-real-time data into reactive transport models. The data collected from this experiment will allow the determination as to whether reduction due to bacterial growth results in current increases, or whether other factors in the soil may account for the current. Additional information concerning the tipping points for geochemical changes in porosity and their effect on signals from the electrode-based microbial monitoring may also be observed. The results of this work will allow the creation of a new data set collected from a more comprehensive monitoring network and will allow stakeholders at a site to develop effective decision-making tools on the long-term management of the site. The additional data will also aid in the long-term prediction abilities of a reactive transport model for a given site. As in situ bioremediation offers a low cost alternative to ex situ treatment methods, the results of this work will help to both reduce cost at existing sites and enable treatment of sites that otherwise have no clear solution.

  9. Airborne geophysical study in the pensacola mountains of antarctica

    USGS Publications Warehouse

    Behrendt, John C.; Meister, L.; Henderson, J.R.

    1966-01-01

    A seismic reflection, gravity, and aeromagnetic reconnaissance was made in the Pensacola Mountains, Antarctica, during the 1965-66 austral summer. Prominent ice streams located between the Neptune and Patuxent Ranges and east of the Forrestal Range overlie channels in the rock surface 2000 meters below sea level which are probably of glacial origin. Seismic reflections show that the Filchner Ice Shelf is 1270 meters thick near its southern margin. Along the boundary between West and East Antarctica, Bouguer anomalies decrease from +60 milligals in West Antarctica to -80 milligals in East Antarctica. An abrupt change in crustal structure across this boundary is required to explain the 2 milligals per kilometer gradient. This may indicate a fault extending through the crust into the mantle. Aeromagnetic profiles delineate anomalies up to 1800 ?? associated with the basic stratiform intrusion which comprises the Dufek and Forrestal ranges. A probable minimum area of 9500 square kilometers is calculated for the intrusive body on the basis of the magnetic anomalies, making it one of the largest bodies of its type. The extension of this magnetic anomaly across a fault forming the north border of the Pensacola Mountains probably precludes transcurrent movement.

  10. Evaluation of airborne thermal, magnetic, and electromagnetic characterization technologies

    SciTech Connect

    Josten, N.E.

    1992-03-01

    The identification of Buried Structures (IBS) or Aerial Surveillance Project was initiated by the US Department of Energy (DOE) Office of Technology Development to demonstrate airborne methods for locating and identifying buried waste and ordnance at the Idaho National Engineering Laboratory (INEL). Two technologies were demonstrated: (a) a thermal infrared imaging system built by Martin Marietta Missile Systems and (b) a magnetic and electromagnetic (EM) geophysical surveying system operated by EBASCO Environmental. The thermal system detects small differences in ground temperature caused by uneven heating and cooling of the ground by the sun. Waste materials on the ground can be detected when the temperature of the waste is different than the background temperature. The geophysical system uses conventional magnetic and EM sensors. These sensors detect disturbances caused by magnetic or conductive waste and naturally occurring magnetic or conductive features of subsurface soils and rock. Both systems are deployed by helicopter. Data were collected at four INEL sites. Tests at the Naval Ordnance Disposal Area (NODA) were made to evaluate capabilities for detecting ordnance on the ground surface. Tests at the Cold Simulated Waste Demonstration Pit were made to evaluate capabilities for detecting buried waste at a controlled site, where the location and depth of buried materials are known. Tests at the Subsurface Disposal Area and Stationary Low-Power Reactor-1 burial area were made to evaluate capabilities for characterizing hazardous waste at sites that are typical of DOE buried waste sites nationwide.

  11. INEL cold test pit demonstration of improvements in information derived from non-intrusive geophysical methods over buried waste sites. Phase 2, Final report

    SciTech Connect

    Not Available

    1994-04-29

    Under Contract between US DOE Idaho National Engineering Laboratory (INEL) and the Blackhawk Geosciences Division of Coleman Research Corporation (BGD-CRC), geophysical investigations were conducted to improve the detection of buried wastes. Site characterization is a costly and time consuming process with the most costly components being drilling, sampling, and chemical analysis of samples. There is a focused effort at US DOE and other agencies to investigate methodologies that reduce costs and shorten the time between characterization and clean-up. These methodologies take the form of employing non-invasive (geophysical) and minimal invasive (e.g., cone penetrometer driving) techniques of characterization, and implementing a near real-time, rational decision-making process (Expedited Site Characterization). Over the Cold Test Pit (CTP) at INEL, data were acquired with multiple sensors on a dense grid. Over the CTP the interpretations inferred from geophysical data are compared with the known placement of various waste forms in the pit. The geophysical sensors employed were magnetics, frequency and time domain electromagnetics, and ground penetrating radar. Also, because of the high data density acquired, filtering and other data processing and imaging techniques were tested. The conclusions derived from the geophysical surveys were that pit boundaries, berms between cells within the pit, and individual objects placed in the pit were best mapped by the new Geonics EM61 time domain EM metal detector. Part of the reason for the effectiveness of the time domain metal detector is that objects buried in the pit are dominantly metallic. Also, the utility of geophysical data is significantly enhanced by dimensional and 3-dimensional imaging formats. These images will particularly assist remediation engineers in visualizing buried wastes.

  12. Geophysical Fiber Interferometer Gyroscope.

    DTIC Science & Technology

    1979-12-31

    gravitational antenna. Basically, their device was a Twyman -Green laser interferometer that was allegedly well-isolated from its thermal and...r ~AD-AO92 913 UTAH UNIV RESEARCH INST SALT LAKE CITY GEOSPACE SCIE-EYC F/B 20/6 GEOPHYSICAL FIBER INTERFEROMETER GYROSCOPE(U) .S DEC 79 L 0 WEAVER...ACCESSION no: S, 111CIPIENT’S CATALOG NUMBER AF6ii M_ __ _ __I_ _ 4. TItLIL (eovm4jk"IU .TYEo nPaTawn.ocoet GEOPHYSICAL FIBER INTERFEROMETER GYROSCOPE. / 9

  13. Teaching oriented geophysical software

    NASA Astrophysics Data System (ADS)

    Pinto, Victor; Rivero, Lluis; Casas, Albert

    2000-08-01

    Interactive teaching techniques encourage students to adopt an active role in their education and should therefore be used at different levels of the teaching sequence. In order to mitigate the lack of educational software for Applied Geophysics, a fully interactive graphic software has been developed. The program is written in Visual Basic with some subroutines in FORTRAN and is designed for IBM-PC microcomputers using a Windows environment. The program offers the majority of the processes involved in geophysical data handling, modelling, tutorials, and instrument simulators.

  14. A method for computing the damage level due to the exposure to an airborne chemical with a time-varying concentration.

    PubMed

    Acquesta, Alejandro D; Sánchez, Erica Yanina; Porta, Andres; Jacovkis, Pablo M

    2011-09-01

    The calculation of damage level due to the exposure to a toxic cloud is usually not included in most popular software, or it is included using techniques that do not take into account the variation in concentration over a period of time. In this work, a method is introduced for calculating the temporal evolution of the potential damage level and to obtain a more precise and descriptive estimation of this level. The proposed goal is: to estimate the maximum and minimum damage level experienced by a population due to the exposure to an airborne chemical with a time-varying concentration; to be able to assess the damage level experienced in a progressive way, as the exposure to the airborne chemical occurs. The method relies on transformations of time-concentration pairs on a continuum of damage level curves based on the available guideline levels, obtaining maximum and minimum approximations of the expected damage level for any exposure duration. Consequently, applying this method to transport model output data and demographic information, damage evolution in relation to time and space can be predicted, as well as its effect on the local population, which enables the determination of threat zones. The comparison between the proposed method and the current (Spanish and ALOHA) ones showed that the former can offer a more precise estimation and a more descriptive approach of the potential damage level. This method can be used by atmospheric dispersion models to compute damage level and graphically display the regions exposed to each guideline level on area maps.

  15. A classifying method analysis on the number of returns for given pulse of post-earthquake airborne LiDAR data

    NASA Astrophysics Data System (ADS)

    Wang, Jinxia; Dou, Aixia; Wang, Xiaoqing; Huang, Shusong; Yuan, Xiaoxiang

    2016-11-01

    Compared to remote sensing image, post-earthquake airborne Light Detection And Ranging (LiDAR) point cloud data contains a high-precision three-dimensional information on earthquake disaster which can improve the accuracy of the identification of destroy buildings. However after the earthquake, the damaged buildings showed so many different characteristics that we can't distinguish currently between trees and damaged buildings points by the most commonly used method of pre-processing. In this study, we analyse the number of returns for given pulse of trees and damaged buildings point cloud and explore methods to distinguish currently between trees and damaged buildings points. We propose a new method by searching for a certain number of neighbourhood space and calculate the ratio(R) of points whose number of returns for given pulse greater than 1 of the neighbourhood points to separate trees from buildings. In this study, we select some point clouds of typical undamaged building, collapsed building and tree as samples from airborne LiDAR point cloud data which got after 2010 earthquake in Haiti MW7.0 by the way of human-computer interaction. Testing to get the Rvalue to distinguish between trees and buildings and apply the R-value to test testing areas. The experiment results show that the proposed method in this study can distinguish between building (undamaged and damaged building) points and tree points effectively but be limited in area where buildings various, damaged complex and trees dense, so this method will be improved necessarily.

  16. Probing The Buried Remains of The Todos los Santos, City of San Salvador in Hoping Island with Shallow Subsurface Geophysics Method

    NASA Astrophysics Data System (ADS)

    Tsai, Yi-fan; Chang, Pin-yu; Eugenio Borao Mateo, José

    2013-04-01

    The study in ancient sites with GPR is widely documented over several decades. This non-invasive geophysical method provides a rapid measure for anthropogenic objects and therefore serves as a guide for possible excavation for the next stage of archaeological surveys. City of San Salvador, which is a Dutch colonial city consisted of fortress, hospitals and churches in 17 century, is located in the Hoping Island in Keelung, Taiwan. The fortress and its affiliated structures were abandoned and left collapsing since the mid-17th century. Some relics of the fortress wall were still remained until the early 20th century but the fast development projects in the island has caused the relics demolished or buried under building or road pavements. Many wells and bones have been found around the area belong to over three hundred years ago. As a consequence, the government initiated a new excavation project at the parking lot where the ancient convent of Todos los Santos is believed since 2011 in order to find the remains of the convent in city of San Salvador. Meanwhile we have surveyed with GPR to help guiding the excavation location. In this case, we surveyed with wide-angle-refraction/reflection (WARR) of GPR as well as common-offset array, to compensate the defect of traditional common-offset of lack of longitudinal resolution with velocity profile, and the combination of velocity profile and common-offset data helped distinguish the signals from other noises and further located the position of subsurface structures. After data analysis and numerical modeling of the buried materials, we have located the possible remains of walls of the convent or other structures around 0.9 to 1.3 meters in depth that can offer useful information to better plan the archaeological excavations.

  17. Integration of geological, geochemical, and geophysical spatial data of the Cement oil field, Oklahoma, test site

    USGS Publications Warehouse

    Termain, Patricia A.; Donovan, Terrence J.; Chavez, Pat S.; Barringer, Anthony R.

    1980-01-01

    Measurement pertaining to geology, geochemistry, and geophysics of the Cement oil field, Oklahoma, test site were collected employing both airborne sensors and ground-based data collection. The measurements include: (1) airborne gamma-ray spectrometry (supplying bismuth 214, thalium 208, and potassium 40 gamma-ray intensities); (2) aeromagnetic survey data; (3) multi-frequency airborne resistivity survey data (supplying apparent electrical resistivity of near surface materials); (4) gravity data; (5) geological and topographic maps; and (6) image data from Landsat MSS and U-2 photography.

  18. Airborne gravity measurement over sea-ice: The western Weddel Sea

    SciTech Connect

    Brozena, J.; Peters, M. ); LaBrecque, J.; Bell, R.; Raymond, C. )

    1990-10-01

    An airborne gravity study of the western Weddel Sea, east of the Antarctic Peninsula, has shown that floating pack-ice provides a useful radar altimetric reference surface for altitude and vertical acceleration corrections surface for alititude and vertical acceleration corrections to airborne gravimetry. Airborne gravimetry provides an important alternative to satellite altimetry for the sea-ice covered regions of the world since satellite alimeters are not designed or intended to provide accurate geoidal heights in areas where significant sea-ice is present within the radar footprint. Errors in radar corrected airborne gravimetry are primarily sensitive to the variations in the second derivative of the sea-ice reference surface in the frequency pass-band of interest. With the exception of imbedded icebergs the second derivative of the pack-ice surface closely approximates that of the mean sea-level surface at wavelengths > 10-20 km. With the airborne method the percentage of ice coverage, the mixture of first and multi-year ice and the existence of leads and pressure ridges prove to be unimportant in determining gravity anomalies at scales of geophysical and geodetic interest, provided that the ice is floating and not grounded. In the Weddell study an analysis of 85 crosstrack miss-ties distributed over 25 data tracks yields an rms error of 2.2 mGals. Significant structural anomalies including the continental shelf and offsets and lineations interpreted as fracture zones recording the early spreading directions within the Weddell Sea are observed in the gravity map.

  19. Voxel inversion of airborne electromagnetic data for improved groundwater model construction and prediction accuracy

    NASA Astrophysics Data System (ADS)

    Kruse Christensen, Nikolaj; Ferre, Ty Paul A.; Fiandaca, Gianluca; Christensen, Steen

    2017-03-01

    We present a workflow for efficient construction and calibration of large-scale groundwater models that includes the integration of airborne electromagnetic (AEM) data and hydrological data. In the first step, the AEM data are inverted to form a 3-D geophysical model. In the second step, the 3-D geophysical model is translated, using a spatially dependent petrophysical relationship, to form a 3-D hydraulic conductivity distribution. The geophysical models and the hydrological data are used to estimate spatially distributed petrophysical shape factors. The shape factors primarily work as translators between resistivity and hydraulic conductivity, but they can also compensate for structural defects in the geophysical model. The method is demonstrated for a synthetic case study with sharp transitions among various types of deposits. Besides demonstrating the methodology, we demonstrate the importance of using geophysical regularization constraints that conform well to the depositional environment. This is done by inverting the AEM data using either smoothness (smooth) constraints or minimum gradient support (sharp) constraints, where the use of sharp constraints conforms best to the environment. The dependency on AEM data quality is also tested by inverting the geophysical model using data corrupted with four different levels of background noise. Subsequently, the geophysical models are used to construct competing groundwater models for which the shape factors are calibrated. The performance of each groundwater model is tested with respect to four types of prediction that are beyond the calibration base: a pumping well's recharge area and groundwater age, respectively, are predicted by applying the same stress as for the hydrologic model calibration; and head and stream discharge are predicted for a different stress situation. As expected, in this case the predictive capability of a groundwater model is better when it is based on a sharp geophysical model instead of a

  20. Geophysical investigation at Fort Detrick Maryland. Final report

    SciTech Connect

    Llopis, J.L.; Simms, J.E.

    1993-07-01

    Results of a comprehensive, integrated geophysical investigation of 15 suspected disposal areas at Area B, Fort Detrick, Maryland, are presented. Between 1943 and 1969, Fort Detrick served as the nation's center for military offensive and defensive biological research. As a result of this activity, chemically and biologically contaminated materials were generated and disposed in burial pits at Site B. Based on historical and visual information, 15 sites suspected of containing burial pits were selected to be examined in greater detail using geophysical methods. The geophysical investigations were designed to detect anomalous conditions indicative of past disposal activities. The geophysical program included electromagnetic (EM), magnetic, ground penetrating radar (GPR), and seismic refraction methods. Anomalous conditions were found at several of the sites tested and noted. The anomalous conditions may have resulted from the presence of buried material or from physical and/or chemical soil changes caused by disposal activities.... Geophysics, Electromagnetics ground penetrating radar, Geophysical surveys, Magnetics, Seismic refraction.

  1. Geophysics News 1990

    NASA Astrophysics Data System (ADS)

    Cole, Stephen

    The last two years have witnessed many major geophysical events such as the Loma Prieta earthquake, new insights into plate motions, new seismic and mid-ocean ridge observational programs, and new views of a distant planet. AGU's Public Information Committee, chaired by Debra Knopman of the U.S. Geological Survey, was asked by the American Institute of Physics to prepare a series of articles on the major topics in geophysics for publication in Physics News in 1990. Several of those papers did appear in the AIP publication. In the absence of a comparable publication devoted solely to a summary of news in geophysics, AGU is publishing the 20 articles solicited by the Public Information Committee as a booklet, Geophysics News 1990, that is being distributed to the media. The articles are also being published in Eos starting with this issue and continuing for the next several weeks. The topics covered in these articles range from the world's deepest rocks to the powerful blast waves from major solar flares.

  2. Terrestrial Planet Geophysics

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.

    2008-12-01

    Terrestrial planet geophysics beyond our home sphere had its start arguably in the early 1960s, with Keith Runcorn contending that the second-degree shape of the Moon is due to convection and Mariner 2 flying past Venus and detecting no planetary magnetic field. Within a decade, in situ surface geophysical measurements were carried out on the Moon with the Apollo program, portions of the lunar magnetic and gravity fields were mapped, and Jack Lorell and his colleagues at JPL were producing spherical harmonic gravity field models for Mars using tracking data from Mariner 9, the first spacecraft to orbit another planet. Moreover, Mariner 10 discovered a planetary magnetic field at Mercury, and a young Sean Solomon was using geological evidence of surface contraction to constrain the thermal evolution of the innermost planet. In situ geophysical experiments (such as seismic networks) were essentially never carried out after Apollo, although they were sometimes planned just beyond the believability horizon in planetary mission queues. Over the last three decades, the discipline of terrestrial planet geophysics has matured, making the most out of orbital magnetic and gravity field data, altimetric measurements of surface topography, and the integration of geochemical information. Powerful constraints are provided by tectonic and volcanic information gleaned from surface images, and the engagement of geologists in geophysical exercises is actually quite useful. Accompanying these endeavors, modeling techniques, largely adopted from the Earth Science community, have become increasingly sophisticated and have been greatly enhanced by the dramatic increase in computing power over the last two decades. The future looks bright with exciting new data sets emerging from the MESSENGER mission to Mercury, the promise of the GRAIL gravity mission to the Moon, and the re-emergence of Venus as a worthy target for exploration. Who knows? With the unflagging optimism and persistence

  3. Spatial scale analysis in geophysics - Integrating surface and borehole geophysics in groundwater studies

    USGS Publications Warehouse

    Paillet, Frederick L.; Singhroy V.H.Hansen D.T.Pierce R, R

    2002-01-01

    Integration of geophysical data obtained at various scales can bridge the gap between localized data from boreholes and site-wide data from regional survey profiles. Specific approaches to such analysis include: 1) comparing geophysical measurements in boreholes with the same measurement made from the surface; 2) regressing geophysical data obtained in boreholes with water-sample data from screened intervals; 3) using multiple, physically independent measurements in boreholes to develop multivariate response models for surface geophysical surveys; 4) defining subsurface cell geometry for most effective survey inversion methods; and 5) making geophysical measurements in boreholes to serve as independent verification of geophysical interpretations. Integrated analysis of surface electromagnetic surveys and borehole geophysical logs at a study site in south Florida indicates that salinity of water in the surficial aquifers is controlled by a simple wedge of seawater intrusion along the coast and by a complex pattern of upward brine seepage from deeper aquifers throughout the study area. This interpretation was verified by drilling three additional test boreholes in carefully selected locations.

  4. TESTING GROUND BASED GEOPHYSICAL TECHNIQUES TO REFINE ELECTROMAGNETIC SURVEYS NORTH OF THE 300 AREA HANFORD WASHINGTON

    SciTech Connect

    PETERSEN SW

    2010-12-02

    Airborne electromagnetic (AEM) surveys were flown during fiscal year (FY) 2008 within the 600 Area in an attempt to characterize the underlying subsurface and to aid in the closure and remediation design study goals for the 200-PO-1 Groundwater Operable Unit (OU). The rationale for using the AEM surveys was that airborne surveys can cover large areas rapidly at relatively low costs with minimal cultural impact, and observed geo-electrical anomalies could be correlated with important subsurface geologic and hydrogeologic features. Initial interpretation of the AEM surveys indicated a tenuous correlation with the underlying geology, from which several anomalous zones likely associated with channels/erosional features incised into the Ringold units were identified near the River Corridor. Preliminary modeling resulted in a slightly improved correlation but revealed that more information was required to constrain the modeling (SGW-39674, Airborne Electromagnetic Survey Report, 200-PO-1 Groundwater Operable Unit, 600 Area, Hanford Site). Both time-and frequency domain AEM surveys were collected with the densest coverage occurring adjacent to the Columbia River Corridor. Time domain surveys targeted deeper subsurface features (e.g., top-of-basalt) and were acquired using the HeliGEOTEM{reg_sign} system along north-south flight lines with a nominal 400 m (1,312 ft) spacing. The frequency domain RESOLVE system acquired electromagnetic (EM) data along tighter spaced (100 m [328 ft] and 200 m [656 ft]) north-south profiles in the eastern fifth of the 200-PO-1 Groundwater OU (immediately adjacent to the River Corridor). The overall goal of this study is to provide further quantification of the AEM survey results, using ground based geophysical methods, and to link results to the underlying geology and/or hydrogeology. Specific goals of this project are as follows: (1) Test ground based geophysical techniques for the efficacy in delineating underlying geology; (2) Use ground

  5. Airborne agent concentration analysis

    DOEpatents

    Gelbard, Fred

    2004-02-03

    A method and system for inferring airborne contaminant concentrations in rooms without contaminant sensors, based on data collected by contaminant sensors in other rooms of a building, using known airflow interconnectivity data. The method solves a least squares problem that minimizes the difference between measured and predicted contaminant sensor concentrations with respect to an unknown contaminant release time. Solutions are constrained to providing non-negative initial contaminant concentrations in all rooms. The method can be used to identify a near-optimal distribution of sensors within the building, when then number of available sensors is less than the total number of rooms. This is achieved by having a system-sensor matrix that is non-singular, and by selecting that distribution which yields the lowest condition number of all the distributions considered. The method can predict one or more contaminant initial release points from the collected data.

  6. High-order Hybridized Discontinuous Galerkin (HDG) method for wave propagation simulation in complex geophysical media (elastic, acoustic and hydro-acoustic); an unifying framework to couple continuous Spectral Element and Discontinuous Galerkin Methods

    NASA Astrophysics Data System (ADS)

    Terrana, Sebastien; Vilotte, Jean-Pierre; Guillot, Laurent; Mariotti, Christian

    2015-04-01

    Today seismological observation systems combine broadband seismic receivers, hydrophones and micro-barometers antenna that provide complementary observations of source-radiated waves in heterogeneous and complex geophysical media. Exploiting these observations requires accurate and multi-physics - elastic, hydro-acoustic, infrasonic - wave simulation methods. A popular approach is the Spectral Element Method (SEM) (Chaljub et al, 2006) which is high-order accurate (low dispersion error), very flexible to parallelization and computationally attractive due to efficient sum factorization technique and diagonal mass matrix. However SEMs suffer from lack of flexibility in handling complex geometry and multi-physics wave propagation. High-order Discontinuous Galerkin Methods (DGMs), i.e. Dumbser et al (2006), Etienne et al. (2010), Wilcox et al (2010), are recent alternatives that can handle complex geometry, space-and-time adaptativity, and allow efficient multi-physics wave coupling at interfaces. However, DGMs are more memory demanding and less computationally attractive than SEMs, especially when explicit time stepping is used. We propose a new class of higher-order Hybridized Discontinuous Galerkin Spectral Elements (HDGSEM) methods for spatial discretization of wave equations, following the unifying framework for hybridization of Cockburn et al (2009) and Nguyen et al (2011), which allows for a single implementation of conforming and non-conforming SEMs. When used with energy conserving explicit time integration schemes, HDGSEM is flexible to handle complex geometry, computationally attractive and has significantly less degrees of freedom than classical DGMs, i.e., the only coupled unknowns are the single-valued numerical traces of the velocity field on the element's faces. The formulation can be extended to model fractional energy loss at interfaces between elastic, acoustic and hydro-acoustic media. Accuracy and performance of the HDGSEM are illustrated and

  7. PICASSO: an end-to-end image simulation tool for space and airborne imaging systems II. Extension to the thermal infrared: equations and methods

    NASA Astrophysics Data System (ADS)

    Cota, Stephen A.; Lomheim, Terrence S.; Florio, Christopher J.; Harbold, Jeffrey M.; Muto, B. Michael; Schoolar, Richard B.; Wintz, Daniel T.; Keller, Robert A.

    2011-10-01

    In a previous paper in this series, we described how The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) tool may be used to model space and airborne imaging systems operating in the visible to near-infrared (VISNIR). PICASSO is a systems-level tool, representative of a class of such tools used throughout the remote sensing community. It is capable of modeling systems over a wide range of fidelity, anywhere from conceptual design level (where it can serve as an integral part of the systems engineering process) to as-built hardware (where it can serve as part of the verification process). In the present paper, we extend the discussion of PICASSO to the modeling of Thermal Infrared (TIR) remote sensing systems, presenting the equations and methods necessary to modeling in that regime.

  8. Study of airborne science experiment management concepts for application to space shuttle, volume 2

    NASA Technical Reports Server (NTRS)

    Mulholland, D. R.; Reller, J. O., Jr.; Neel, C. B.; Haughney, L. C.

    1973-01-01

    Airborne research management and shuttle sortie planning at the Ames Research Center are reported. Topics discussed include: basic criteria and procedures for the formulation and approval of airborne missions; ASO management structure and procedures; experiment design, development, and testing aircraft characteristics and experiment interfaces; information handling for airborne science missions; mission documentation requirements; and airborne science methods and shuttle sortie planning.

  9. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

    PubMed

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-09-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

  10. Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

    PubMed Central

    Kero, Ida Teresia; Jørgensen, Rikke Bramming

    2016-01-01

    The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM), a Fast Mobility Particle Sizer (FMPSTM), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

  11. EXTENT AND KINEMATICS OF ASWA SHEAR ZONE IN UGANDA AND SOUTH SUDAN USING AIRBORNE GEOPHYSICAL AND REMOTE SENSING DATA. A. Katumwehe. 1, E. A. Atekwana. 1, M.G. Abdelsalam.1 1Oklahoma State University, Boone Pickens School of Geology, Stillwater, USA

    NASA Astrophysics Data System (ADS)

    katumwehe, A. B.; Atekwana, E. A.; Abdel Salam, M. G.

    2012-12-01

    The Aswa Shear zone (ASZ) is a fundamental Precambrian lithospheric structure playing an important role in the evolution of the Mesozoic South Sudan rifts, the propagation of the Cenozoic East African Rift System (EARS), the eruption of EARS shield volcanoes (Mt Kilimanjaro and Mt Elgon), re-organization of drainage systems (the White Nile), and the distribution of recent seismicity in South Sudan. Traces of the shear zone have been mapped extending in central and east Africa in a NW-SE direction from South Sudan in the northwest through Uganda and Tanzania to the southeast and possibly into Madagascar. Gondwana reconstructions suggest that the ASZ continues further southeast into south India. Nonetheless, the kinematics and extent of the ASZ have not been fully understood because of limited exposure. In areas where it is exposed the shear zone is expressed by narrow dominantly NW-trending outcrops. We use recently acquired high resolution airborne magnetic and radiometric data over Uganda integrated with 90 m spatial resolution Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) and 30 m spatial resolution Landsat Thematic Mapper (TM) spectral data to elucidate the kinematics and ascertain the significance of the ASZ in the development of the EARS and the tectonic architecture of east and central Africa. Vertical derivative, Euler deconvolution and analytical signal filters were applied to the total field magnetic data to image the shallow subsurface structures associated with the ASZ while upward continuation (5000 m) was applied to assess the ASZ depth continuity. We also used radiometric data to create ternary images while SRTM and Landsat TM data were used to map the surface expression of the shear zone. The geophysical data from Uganda suggest that the ASZ is characterised by a 50-60 km wide corridor of ductile deformation associated with NW-trending strike-slip shearing. It is dominated by three, equally-spaced and discrete sinistral strike

  12. Infrared airborne spectroradiometer survey results in the western Nevada area

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.; Kuo, J. T.

    1982-01-01

    The Mark II airborne spectroradiometer system was flown over several geologic test sites in western Nevada. The infrared mineral absorption bands were observed and recorded for the first time using an airborne system with high spectral resolution in the 2.0 to 2.5 micron region. The data show that the hydrothermal alteration zone minerals, carbonates, and other minerals are clearly visible in the airborne survey mode. The finer spectral features that distinguish the various minerals with infrared bands are also clearly visible in the airborne survey data. Using specialized computer pattern recognition methods, it is possible to identify mineralogy and map alteration zones and lithologies by airborne spectroradiometer survey techniques.

  13. A German Geophysics School Project First steps to bring geophysical topics to schoolclasses

    NASA Astrophysics Data System (ADS)

    Schneider, S.

    2002-12-01

    In Germany Geophysics is a science with almost none or a bad reputation. People do not know to distinguish between Geophysics, Geography and Geology. In order to change the public view on Geosciences, a,School Project Geophysics' is going to be created at the Institute of Meteorology and Geophysics, Johann Wolfgang Goethe University, Frankfurt, which will offer geophysical ideas, methodes and scientific results to schoolclasses. After researches like PISA or TIMSS (third international Math and Nature-Science test) new concepts in education will be required. Interdisciplinary tasks are demanded by national and international commissions.\\The,School Project Geophysics' will be created to bring geophysical themes and results of scientific research into schools. One Day- or one Week-Workshops will help to publish geophysical contents in close cooperation with Physics - and Geography - teachers.\\Hands-on experiments (for advanced pupils) like refraction-Seismics or Magnetic measurements will lead students closer to scientific work and will help to establish personal interests in Earthsciences. Working with personally produced datasets will show the basics of inversion theory and point out the difficulties in creating models. Boundaries of data interpretation (the plurality of variables needed) will teach the school children to see scientific and statistic predictions and declarations more criticaly. Animations and Videos will present global examples (for example of volcanoes or Earthquakes) and lead over to regional sites. Excursions to these sites will help to show fieldwork methods and its problems and will convince to take a different look on topography and landscapes.\\All necessary utilities (Animations, Videos, Pictures and foils) will be offered to teachers in an online-data base which will be installed and managed by the project. Teachers and pupils might get easily into contact with Scientists to discuss geoscientific items. Further on extensions to geographic

  14. High-Order Hybridized Discontinuous Galerkin (HDG) Method for Wave Propagation Simulation in Complex Geophysical Media - Elastic, Acoustic and Hydro-Acoustic - an Unifying Framework to Couple Continuous Spectral Element and Discontinuous Galerkin Methods.

    NASA Astrophysics Data System (ADS)

    Sébastien, T.; Vilotte, J. P.; Guillot, L.; Mariotti, C.

    2014-12-01

    Today seismological observation systems combine broadband seismic receivers, hydrophones and micro-barometers antenna that provide complementary observations of source-radiated waves in heterogeneous and complex geophysical media. Exploiting these observations requires accurate and multi-physics - elastic, hydro-acoustic, infrasonic - wave simulation methods. A popular approach is the Spectral Element Method (SEM) (Chaljub et al, 2006) which is high-order accurate (low dispersion error), very flexible to parallelization and computationally attractive due to efficient sum factorization technique and diagonal mass matrix. However SEMs suffer from lack of flexibility in handling complex geometry and multi-physics wave propagation. High-order Discontinuous Galerkin Methods (DGMs), i.e. Dumbser et al (2006), Etienne et al. (2010), Wilcox et al (2010), are recent alternatives that can handle complex geometry, space-and-time adaptativity, and allow efficient multi-physics wave coupling at interfaces. However, DGMs are more memory demanding and less computationally attractive than SEMs, especially when explicit time stepping is used. We propose a new class of higher-order Hybridized Discontinuous Galerkin Spectral Elements (HDGSEM) methods for spatial discretization of wave equations, following the unifying framework for hybridization of Cockburn et al (2009) and Nguyen et al (2011), which allows for a single implementation of conforming and non-conforming SEMs. When used with energy conserving explicit time integration schemes, HDGSEM is flexible to handle complex geometry, computationally attractive and has significantly less degrees of freedom than classical DGMs, i.e., the only coupled unknowns are the single-valued numerical traces of the velocity field on the element's faces. The formulation can be extended to model fractional energy loss at interfaces between elastic, acoustic and hydro-acoustic media. Accuracy and performance of the HDGSEM are illustrated and

  15. A New Method To Monitor Airborne Inoculum of the Fungal Plant Pathogens Mycosphaerella brassicicola and Botrytis cinerea

    PubMed Central

    Kennedy, R.; Wakeham, A. J.; Byrne, K. G.; Meyer, U. M.; Dewey, F. M.

    2000-01-01

    We describe a new microtiter immunospore trapping device (MTIST device) that uses a suction system to directly trap air particulates by impaction in microtiter wells. This device can be used for rapid detection and immunoquantification of ascospores of Mycosphaerella brassicicola and conidia of Botrytis cinerea by an enzyme-linked immunosorbent assay (ELISA) under controlled environmental conditions. For ascospores of M. brassicicola correlation coefficients (r2) of 0.943 and 0.9514 were observed for the number of MTIST device-impacted ascospores per microtiter well and the absorbance values determined by ELISA, respectively. These values were not affected when a mixed fungal spore population was used. There was a relationship between the number of MTIST device-trapped ascospores of M. brassicicola per liter of air sampled and the amount of disease expressed on exposed plants of Brassica oleracea (Brussels sprouts). Similarly, when the MTIST device was used to trap conidia of B. cinerea, a correlation coefficient of 0.8797 was obtained for the absorbance values generated by the ELISA and the observed number of conidia per microtiter well. The relative collection efficiency of the MTIST device in controlled plant growth chambers with limited airflow was 1.7 times greater than the relative collection efficiency of a Burkard 7-day volumetric spore trap for collection of M. brassicicola ascospores. The MTIST device can be used to rapidly differentiate, determine, and accurately quantify target organisms in a microflora. The MTIST device is a portable, robust, inexpensive system that can be used to perform multiple tests in a single sampling period, and it should be useful for monitoring airborne particulates and microorganisms in a range of environments. PMID:10877797

  16. A Newly Adopted Helicopter Platform for Geophysical and Remote Sensing

    NASA Astrophysics Data System (ADS)

    Meyer, Uwe

    2014-05-01

    The Federal Institute for Geosciences and Natural Resources in Hannover owns a Sikorsky S-76B helicopter for geophysical and remote sensing airborne surveys. This platform has been completely refurbished and in parts newly designed to be fit for easy installations of complex geophysical instruments underneath, upon and within the helicopter. The airborne platform is equipped with a modern basic navigation equipment consisting of several GNSS antennae, state of the art inertial navigation systems, laser altimeter and video camera systems. Different other modules can be added to the helicopter as a state of the art gamma spectrometer, a laser scanner, airborne gravity meters etc. within the cabin. Moreover, external sensing systems as a photogrammetric camera, infraread camera or optional mulitspectral systems can be installed on the outer skin of the cabin. Different kinds of bird systems towed underneath the helicopter can be hooked up using standard cabling, glas fibres or wireless LAN. Available birds are equipped for frequency domain electromagnetics or gradient magnetics (IPHT Jena & Supracon, Jena). Besides, large georadar systems can be installed as well. The helicopter is able as well to carry TEM-gear or system in development. Main survey targets are groundwater systems, mineral deposits and natural hazards.

  17. Principles for Sampling Airborne Radioactivity from Stacks

    SciTech Connect

    Glissmeyer, John A.

    2010-10-18

    This book chapter describes the special processes involved in sampling the airborne effluents from nuclear faciities. The title of the book is Radioactive Air Sampling Methods. The abstract for this chapter was cleared as PNNL-SA-45941.

  18. Groundwater contamination in the basement-complex area of Ile-Ife, southwestern Nigeria: A case study using the electrical-resistivity geophysical method

    NASA Astrophysics Data System (ADS)

    Adepelumi, A. A.; Ako, B. D.; Ajayi, T. R.

    2001-11-01

    Hydrogeoenvironmental studies were carried out at the sewage-disposal site of Obafemi Awolowo University campus, Ile-Ife, Nigeria. The objective of the survey was to determine the reliability of the electrical-resistivity method in mapping pollution plumes in a bedrock environment. Fifty stations were occupied with the ABEM SAS 300C Terrameter using the Wenner array. The electrical-resistivity data were interpreted by a computer-iteration technique. Water samples were collected at a depth of 5.0 m in 20 test pits and analyzed for quality. The concentrations of Cr, Cd, Pb, Zn, and Cu are moderately above the World Health Organization recommended guidelines. Plumes of contaminated water issuing from the sewage ponds were delineated. The geoelectric sections reveal four subsurface layers, with increasing depth, lateritic clay, clayey sand/sand, and weathered/fractured bedrock, and fresh bedrock. The deepest layers, 3 and 4, constitute the main aquifer, which has a thickness of 3.1-67.1 m. The distribution of the elements in the sewage effluent confirms a hydrological communication between the disposal ponds and groundwater. The groundwater is contaminated, as shown by sampling and the geophysical results. Thus, the results demonstrate the reliability of the direct-current electrical-resistivity geophysical method in sensing and mapping pollution plumes in a crystalline bedrock environment. Résumé. Des études géo-environnementales ont été réalisées sur le site d'épandages du campus universitaire d'Obafemi Awolowo, à Ile-Ife (Nigeria). L'objectif de ce travail était de déterminer la fiabilité de la méthode des résistivités électriques pour cartographier les panaches de pollution dans un environnement de socle. Cinquante stations ont été soumises à mesures au moyen d'un ABEM SAS 300C Terrameter en utilisant le dispositif de Wenner. Les données de résistivité électrique ont été interprétées au moyen d'une technique de calcul itérative. Des

  19. Use of Geophysical and Remote Sensing Techniques During the Comprehensive Test Ban Treaty Organization's Integrated Field Exercise 2014

    NASA Astrophysics Data System (ADS)

    Labak, Peter; Sussman, Aviva; Rowlands, Aled; Chiappini, Massimo; Malich, Gregor; MacLeod, Gordon; Sankey, Peter; Sweeney, Jerry; Tuckwell, George

    2016-04-01

    The Integrated Field Exercise of 2014 (IFE14) was a field event held in the Hashemite Kingdom of Jordan (with concurrent activities in Austria) that tested the operational and technical capabilities of a Comprehensive Test Ban Treaty's (CTBT) on-site inspection (OSI). During an OSI, up to 40 inspectors search a 1000km2 inspection area for evidence of a nuclear explosion. Over 250 experts from ~50 countries were involved in IFE14 (the largest simulation of an OSI to date) and worked from a number of different directions, such as the Exercise Management and Control Teams to execute the scenario in which the exercise was played, to those participants performing as members of the Inspection Team (IT). One of the main objectives of IFE14 was to test Treaty allowed inspection techniques, including a number of geophysical and remote sensing methods. In order to develop a scenario in which the simulated exercise could be carried out, a number of physical features in the IFE14 inspection area were designed and engineered by the Scenario Task Force Group (STF) that the IT could detect by applying the geophysical and remote sensing inspection technologies, as well as other techniques allowed by the CTBT. For example, in preparation for IFE14, the STF modeled a seismic triggering event that was provided to the IT to prompt them to detect and localize aftershocks in the vicinity of a possible explosion. Similarly, the STF planted shallow targets such as borehole casings and pipes for detection by other geophysical methods. In addition, airborne technologies, which included multi-spectral imaging, were deployed such that the IT could identify freshly exposed surfaces, imported materials and other areas that had been subject to modification. This presentation will introduce the CTBT and OSI, explain the IFE14 in terms of goals specific to geophysical and remote sensing methods, and show how both the preparation for and execution of IFE14 meet those goals.

  20. Geophysical Exploration of Castle Remains in Barwałd Górny (Near Kalwaria Zebrzydowska, Poland) Using Electrical Resistivity Tomography (ERT) with Assistance of Depth of Investigation Index (DOI) Method.

    NASA Astrophysics Data System (ADS)

    Glazer, Michał; Kula, Damian; Saternus, Robert; Lewicki, Paweł

    2014-09-01

    In March of 2014 at ruins of the 14th century castle, situated at the top of Mount Żar in Małopolska region, Poland, geophysical surveys were performed. Surveys were planned to investigate remains of the castle that could remain in the ground. Electrical Resistivity Tomography method was used there. In the paper 4 sections have been presented. During interpretation, as the supporting method, maps of Depth-of-Investigation (DOI) index have been used. Results of the surveys can point out potential remains of the castle walls and ruins of buildings that were situated in the stronghold

  1. Introduction to the JEEG Agricultural Geophysics special issue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent advancements such as the availability of personal computers, technologies to store/process large amounts of data, the GPS, and GIS have now made geophysical methods practical for agricultural use. Consequently, there has been a rapid expansion of agricultural geophysics research just over the...

  2. Airborne detection of asperities: Linking aerogravimetry surveys and earthquake studies

    NASA Astrophysics Data System (ADS)

    Meyer, U.; Boedecker, G.

    2003-04-01

    During the last decade, airborne gravimetric surveys have become a reliable and useful geophysical method to explore mid to large scale geologic settings. Ocean continent boundaries down to seamounts are detectable using conventional scalar, platform stabilized airborne gravimetry systems. New systems such as 3-D strap-down instruments promise a better spatial resolution recovering the gravity vector. Airborne gravimetric gradiometer systems are already able to detect small scale gradients in high spatial resolution. Following this trend in aerogravimetry, new research applications are emerging. One of the most challenging and interesting new aspects of airborne gravimetry is the systematic search for asperity structures. Asperities are patches of the oceanic or continental crust that are able to store more stress than the surrounding material. If due to stress overload or other mechanic forces the asperity breaks, up to mega-thrust earthquakes are triggered. The character of an asperity to carry more stress than the weaker environment must be related to its physical properties such as composition, thickness and density. Questions connected to define and detect an asperity are: How large is an asperity? Do asperities have sharp boundaries? Are asperities isolated structures? Do asperities have special gravimetric signatures? Wells et al. (2000) found that off southern Chile slip maxima from earthquakes coincide with forearc gravity lows. It is well accepted that in this region seismicity is a product of the subduction on the active continental margin. It is still debated whether subducted asperities from the oceanic plate are individual earthquake sources or if they i.e. trigger the break of asperities in the continental crust. Apart from this, very few investigations have been made trying to connect gravimetry and asperities. Therefore, the GeoForschungsZentrum Potsdam in collaboration with Bayerische Akademie der Wissenschaften in Munich , FU Berlin

  3. Brief overview of geophysical probing technology

    SciTech Connect

    Ramirez, A.L.; Lytle, R.J.

    1982-02-01

    An evaluation of high-resolution geophysical techniques which can be used to characterize a nulcear waste disposal site is being conducted by the Lawrence Livermore National Laboratory (LLNL) at the request of the US Nuclear Regulatory Commisson (NRC). LLNL is involved in research work aimed at evaluating the current capabilities and limitations of geophysical methods used for site selection. This report provides a brief overview of the capabilities and limitations associated with this technology and explains how our work addresses some of the present limitations. We are examining both seismic and electromagnetic techniques to obtain high-resolution information. We are also assessing the usefulness of geotomography in mapping fracture zones remotely. Finally, we are collecting core samples from a site in an effort to assess the capability of correlating such geophysical data with parameters of interest such as fracture continuity, orientation, and fracture density.

  4. Geological and geophysical characteristics of massive sulphide deposits: A case study of the Lirhanda massive sulphide deposit of Western Kenya

    NASA Astrophysics Data System (ADS)

    Dindi, E.; Maneno, J. B. J.

    2016-08-01

    An integrated geophysical ground survey was conducted on an airborne electromagnetic (EM) anomaly located in Kakamega forest of Western Kenya. The purpose of the study was to establish the existence of massive sulphides and identify suitable optimal geophysical method(s) for the investigation of similar anomalies. The study was also expected to provide information on the geological and geophysical characteristics of the deposit. Field work involved electromagnetic methods: Vertical Loop (VLEM), Horizontal Loop (HLEM), TURAM EM and potential field methods: gravity and magnetics. Geochemical sampling was carried out concurrently with the geophysical survey. All the geophysical methods used yielded good responses. Several conductors conforming to the strike of the geology were identified. TURAM EM provided a higher resolution of the conductors compared to VLEM and HLEM. The conductors were found to be associated with positive gravity anomalies supporting the presence of bodies of higher density than the horst rock. Only the western section (west of 625W) of the grid is associated with strong magnetic anomalies. East of 625W strong EM and gravity anomalies persist but magnetic anomalies are weak. This may reflect variation in the mineral composition of the conductors from magnetic to non-magnetic. Geochemical data indicates strong copper anomalies (upto 300 ppm) over sections of the grid and relatively strong zinc (upto 200 ppm) and lead (upto 100 ppm) anomalies. There is a positive correlation between the location of the conductors as predicted by TURAM EM and the copper and zinc anomalies. A test drill hole proposed on the basis of the geophysical results of this study struck massive sulphides at a depth of 30m still within the weathered rock zone. Unfortunately, the drilling was stopped before the sulphides could be penetrated. The drill core revealed massive sulphide rich in pyrite and pyrrhotite. An attempt has been made to compare characteristics of the Lirhanda

  5. SURFACE GEOPHYSICAL EXPLORATION - COMPENDIUM DOCUMENT

    SciTech Connect

    RUCKER DF; MYERS DA

    2011-10-04

    This report documents the evolution of the surface geophysical exploration (SGE) program and highlights some of the most recent successes in imaging conductive targets related to past leaks within and around Hanford's tank farms. While it is noted that the SGE program consists of multiple geophysical techniques designed to (1) locate near surface infrastructure that may interfere with (2) subsurface plume mapping, the report will focus primarily on electrical resistivity acquisition and processing for plume mapping. Due to the interferences from the near surface piping network, tanks, fences, wells, etc., the results of the three-dimensional (3D) reconstruction of electrical resistivity was more representative of metal than the high ionic strength plumes. Since the first deployment, the focus of the SGE program has been to acquire and model the best electrical resistivity data that minimizes the influence of buried metal objects. Toward that goal, two significant advances have occurred: (1) using the infrastructure directly in the acquisition campaign and (2) placement of electrodes beneath the infrastructure. The direct use of infrastructure was successfully demonstrated at T farm by using wells as long electrodes (Rucker et al., 2010, 'Electrical-Resistivity Characterization of an Industrial Site Using Long Electrodes'). While the method was capable of finding targets related to past releases, a loss of vertical resolution was the trade-off. The burying of electrodes below the infrastructure helped to increase the vertical resolution, as long as a sufficient number of electrodes are available for the acquisition campaign.

  6. Geophysics publications honored

    NASA Astrophysics Data System (ADS)

    Geophysics and geology publications by the U.S. Geological Survey were awarded one first- and two third-place prizes at the ‘Blue Pencil’ ceremony last month, sponsored by the National Association of Government Communicators.First place in the news release category went to Frank Forrester, an AGU member and recently retired USGS information officer. Editors and artists of the bimonthly USGS Earthquake Information Bulletin were awarded third place in the category for technical magazines using at least two colors.

  7. A positive chemical ionization GC/MS method for the determination of airborne ethylene glycol and propylene glycols in non-occupational environments.

    PubMed

    Zhu, Jiping; Feng, Yong-Lai; Aikawa, Bio

    2004-11-01

    An analytical method for ethylene glycol and propylene glycols has been developed for measuring airborne levels of these chemicals in non-occupational environments such as residences and office buildings. The analytes were collected on charcoal tubes, solvent extracted, and analyzed by gas chromatography-mass spectrometry using a positive chemical ionization technique. The method had a method detection limit of 0.07 microg m(-3) for ethylene glycol and 0.03 microg m(-3) for 1,2- and 1,3-propylene glycols, respectively, based on a 1.44 m3 sampling volume. Indoor air samples of several residential homes and other indoor environments have been analyzed. The median concentrations of ethylene glycol and 1,2-propylene glycol in nine residential indoor air samples were 53 microg m(-3) and 13 microg m(-3) respectively with maximum values of 223 microg m(-3) and 25 microg m(-3) detected for ethylene glycol and 1,2-propylene glycol respectively. The concentrations of these two chemicals in one office and two laboratories were at low microg m(-3) levels. The maximum concentration of 1,3-propylene glycol detected in indoor air was 0.1 microg m(-3).

  8. Integrated multidisciplinary processing and interpretation of geophysical data acquired on transects in Barents and Kara seas

    NASA Astrophysics Data System (ADS)

    Roslov, Yu. V.; Sakoulina, T. S.

    2003-04-01

    INTEGRATED MULTIDISCIPLINARY PROCESSING AND INTERPRETATION OF GEOPHYSICAL DATA ACQUIRED ON TRANSECTS IN BARENTS AND KARA SEAS Yu.V. Roslov (1), T.S. Sakoulina (1) (1 - SEVMORGEO State Geophysical Co., 36 Rosenstein St, 198095, St Petersburg, Russia, roslov @sevmorgeo.com) According to Russian arctic offshore transect program State Company Sevmorgeo in cooperation with other Russian state companies carry out multidisciplinary investigations on transects 1-AR and 2-AR in Barents and Kara Seas. Investigations include the following geophysical methods: 4C wide angle refraction/reflection profiling (WARRP), CDP seismic, airborn and/or marine gravity and magnetic. Three levels of the integration has been used on processing and interpretation stage. First, different approaches of kinematic inverse problem and tomographic reconstruction have been applied for kinematic parameters of 4C WARRP data processing. That has allowed extracting of maximum information from the data acquired. As a result stable P and S velocity models have been obtained. Second, dynamic WARRP image focused mainly on Moho boundary has been integrated with CDP image in order to improve the sedimentary layer structure. Third, seismic images have been proven with gravity and magnetic data reaching the model, which fits to observed potential fields. Also gravity and magnetic data successfully fill out information gap in the places where there is a lack of seismic data. Some original technologies of data processing have been developed in the framework of the project. Finally, within the range defined by the data processed the integrated geological-geophysical images the Kara-Barents Shelf Plate structure whole Earth crust thickness along transects 1-AR and 2-AR have been obtained. New geophysical data acquired have forced reviewing of our nderstanding of Barents region geological structure. First of all it concern to south and north Barents depressions. South Barents depression is well known as a geological

  9. Long-term Geophysical Monitoring of Simulated Clandestine Graves using Electrical and Ground Penetrating Radar Methods: 4-6 Years After Burial.

    PubMed

    Pringle, Jamie K; Jervis, John R; Roberts, Daniel; Dick, Henry C; Wisniewski, Kristopher D; Cassidy, Nigel J; Cassella, John P

    2016-03-01

    This ongoing monitoring study provides forensic search teams with systematic geophysical data over simulated clandestine graves for comparison to active cases. Simulated "wrapped," "naked," and "control" burials were created. Multiple geophysical surveys were collected over 6 years, here showing data from 4 to 6 years after burial. Electrical resistivity (twin electrode and ERI), multifrequency GPR, grave and background soil water were collected. Resistivity surveys revealed that the naked burial had low-resistivity anomalies up to year four but then difficult to image, whereas the wrapped burial had consistent large high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed that the wrapped burial could be detected throughout, but the naked burial was either not detectable or poorly resolved. 225-MHz frequency GPR data were optimal. Soil water analyses showed decreasing (years 4 to 5) to background (year 6) conductivity values. Results suggest both resistivity and GPR surveying if burial style unknown, with winter to spring surveys optimal and increasingly important as time increases.

  10. Combination of electromagnetic, geophysical methods and sedimentological studies for the development of 3D models in alluvial sediments affected by karst (Ebro Basin, NE Spain)

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Óscar; Luzón, Aránzazu; Gil Garbi, Héctor; Pérez, Antonio; Pocoví Juan, Andrés; Soriano, María Asunción

    2014-03-01

    An integrated analysis was carried out in a selected quarry of the oldest terrace of the Ebro River, where a wide gravel unit is characterized by large-scale cross bedding outcrops. This unit has been interpreted as a lake with marginal deltas. Previous sedimentological studies have pointed out that braided rivers have dominated in the area during the Early Pleistocene. The presence of a lake, which in stable conditions (without subsidence) could be hardly developed in a braided fluvial setting, supports that a topographic depression pre-existed. The delta gravels suggest a depth of at least 5 m for this depression. Established models from broadband multifrequency electromagnetic survey and ground penetrating radar (GPR) show that the analyzed area was affected by a long-term karstic subsidence, which generated a doline field in which topographic depressions were filled by marls and marginal gravels, and subsequently affected by minor collapses during different subsidence reactivation episodes. A 3D model of the evolution and meaning of the doline field and its interaction with sedimentation has been developed. This model can be applied in other areas where high-resolution geophysical 3D models are difficult to establish because of the limitations of the geophysical surveys due to the presence of interbedded mudstones, subsiding depressions filled by human activities or near surface water levels.

  11. Geophysical Technologies to Image Old Mine Works

    SciTech Connect

    Kanaan Hanna; Jim Pfeiffer

    2007-01-15

    ZapataEngineering, Blackhawk Division performed geophysical void detection demonstrations for the US Department of Labor Mine Safety and Health Administration (MSHA). The objective was to advance current state-of-practices of geophysical technologies for detecting underground mine voids. The presence of old mine works above, adjacent, or below an active mine presents major health and safety hazards to miners who have inadvertently cut into locations with such features. In addition, the presence of abandoned mines or voids beneath roadways and highway structures may greatly impact the performance of the transportation infrastructure in terms of cost and public safety. Roads constructed over abandoned mines are subject to potential differential settlement, subsidence, sinkholes, and/or catastrophic collapse. Thus, there is a need to utilize geophysical imaging technologies to accurately locate old mine works. Several surface and borehole geophysical imaging methods and mapping techniques were employed at a known abandoned coal mine in eastern Illinois to investigate which method best map the location and extent of old works. These methods included: 1) high-resolution seismic (HRS) using compressional P-wave (HRPW) and S-wave (HRSW) reflection collected with 3-D techniques; 2) crosshole seismic tomography (XHT); 3) guided waves; 4) reverse vertical seismic profiling (RVSP); and 5) borehole sonar mapping. In addition, several exploration borings were drilled to confirm the presence of the imaged mine voids. The results indicated that the RVSP is the most viable method to accurately detect the subsurface voids with horizontal accuracy of two to five feet. This method was then applied at several other locations in Colorado with various topographic, geologic, and cultural settings for the same purpose. This paper presents the significant results obtained from the geophysical investigations in Illinois.

  12. Unleashing Geophysics Data with Modern Formats and Services

    NASA Astrophysics Data System (ADS)

    Ip, Alex; Brodie, Ross C.; Druken, Kelsey; Bastrakova, Irina; Evans, Ben; Kemp, Carina; Richardson, Murray; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

    2016-04-01

    . The first geophysical data collection selected for transformation by GA was Airborne ElectroMagnetics (AEM) data which was held in proprietary-format files, with associated ISO 19115 metadata held in a separate relational database. Existing NetCDF-CF metadata profiles were enhanced to cover AEM and other geophysical data types, and work is underway to formalise the new geophysics vocabulary as a proposed extension to the Climate & Forecasting conventions. The richness and flexibility of HDF5's internal indexing mechanisms has allowed lossless restructuring of the AEM data for efficient storage, subsetting and access via either the NetCDF4/HDF5 APIs or Open-source Project for a Network Data Access Protocol (OPeNDAP) data services. This approach not only supports large-scale HPC processing, but also interactive access to a wide range of geophysical data in user-friendly environments such as iPython notebooks and more sophisticated cloud-enabled portals such as the Virtual Geophysics Laboratory (VGL). As multidimensional AEM datasets are relatively complex compared to other geophysical data types, the general approach employed in this project for modernizing AEM data is likely to be applicable to other geophysics data types. When combined with the use of standards-based data services and APIs, a coordinated, systematic modernisation will result in vastly improved accessibility to, and usability of, geophysical data in a wide range of computational environments both within and beyond the geophysics community.

  13. Geophysical and Geologic Training of the Afghan Geological Survey, May, 2008

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Bohannon, R.; Abraham, J.; Medlin, J.

    2008-12-01

    Afghanistan lies within the Alpine-Himalayan orogeny, and consists of four primary tectonic units: (1) the North Afghan Platform, part of the greater Kazakhstan craton that includes Turkmenistan and Uzbekistan; (2) the mountainous Hindu Kush-Pamirs in the northeast; (3) the transpressional plate boundary at the Chaman fault near the border with Pakistan; and (4) the southern accreted terranes located south of the east-west oriented Herat fault. The diverse geology of Afghanistan affords the country abundant natural resources, as well as many natural hazards. In order to assist in the identification of these resources and to map hazardous faults, a multi-agency consortium including the Afghan Ministry of Mines and Industry, the USGS and the US Navel Research Lab conducted a detailed airborne geophysical survey of the western half of Afghanistan during 2007. Over 110,000 km of data were collected, including aeromagnetic, gravity, hyperspectral imagery, synthetic aperture radar and photogrammetric data. These data provide remarkable images of the surficial and sub-surface structure of the country. Armed with these new, high quality data, USGS trainers conducted an in-depth training course at the offices of the Afghan Geological Survey (AGS) during May, 2008. Eighty staff members of the AGS attended the four-day course which covered the following topics: (1) the geology and tectonics of Afghanistan; (2) a synthesis of modern plate tectonic processes; (3) use of geophysical and geological data to identify natural resources and hazardous faults. Particular emphasis was placed on oil and gas, mineral, coal and water resources. Earthquake and landslide hazards in Afghanistan were also discussed in detail. The building of scientific and technical capabilities at the AGS is a high priority because the development of their natural resources will have a positive impact on economic growth in Afghanistan. Future courses will benefit from hands-on training in methods of

  14. Sampling for Airborne Radioactivity

    DTIC Science & Technology

    2007-10-01

    compared to betas, gammas and neutrons. For an airborne radioactivity detection system, it is most important to be able to detect alpha particles and... Airborne radioactive particles may emit alpha, beta, gamma or neutron radiation, depending on which radioisotope is present. From a health perspective...

  15. Exemplary geophysical investigations on coal seam fires in Northern China

    NASA Astrophysics Data System (ADS)

    Lambrecht, A.; Meyer, U.; Rüter, H.; Gundelach, V.; Lindner, H.; Schaumann, G.; Schlömer, S.; Guangliang, L.; Bing, K.; Jianjun, W.

    2009-04-01

    Within the framework of the Sino-German research initiative "Innovative technologies for exploration, extinction and monitoring of coal fires in Northern China" different geophysical methods have been applied. The investigation area was the coal fire district of Wuda, located in the south-central part of the Inner Mongolia Autonomous Region of Northern China. The Wuda coalfield is bordering in southeast with the Helan Shan (Helan Mountains), in the east with the mountains of the Ordos Massif, while in the west and north with the Gobi desert. It is a gentle north-south striking structural syncline with an aerial extent of 40 km2 and with elevations ranging between 1100 and 1300 m above sea level. The survey area is covered mainly by sandstone. Up to 18 mined coal seams extend to greater depths varying from a few metres down to several hundreds of metres below surface. The objective of subsequent geophysical surveys was to detect areas affected by coal seam fires by means of physical parameters acquired over the burning and burnt coal seams, to find out which methods are useful for fire detection, to accompany the extinguishing process and to control successful extinction. Airborne methods used are helicopter borne electromagnetics (HEM) and magnetics. Ground surveys for measuring transient electromagnetics, magnetics, ground penetrating radar and near surface temperature were carried out in selected parts of the helicopter survey. Ground penetrating radar (GPR) is an ideal method to detect voids in depth less than 50 m. An important point to extinguish a coal fire is to know the paths of oxygen transport from the surface to the fire. Some crevices which are potential paths for oxygen can be determined by GPR due to the resolution of the chosen frequency. The GPR system applied was built by GSSI and utilized for three different antennae length. The centre frequencies are 40, 80 and 200 MHz. A 200 MHz system was used to get detailed information close to the surface

  16. Mountain permafrost detection inferred by a combined remote sensing, geomorphological and geophysical approach

    NASA Astrophysics Data System (ADS)

    Klug, Christoph; Mössinger, Max; Ott, Patrick; Rieg, Lorenzo; Sailer, Rudolf; Sass, Oliver; Stötter, Johann

    2013-04-01

    The detection of permafrost in high altitude regions of the Alps is an important aim of alpine studies. Geophysical research in this field is important for alpine risk, infrastructure and climate change studies. Because of the complexity of detecting ground ice, the database of permafrost maps is currently not very well evaluated for wide areas of the Alps. The research for this study was conducted at Rofenberg (Ötztal, Austria), a typical high alpine environment in mid-latitudes, which ranges between 2800 and 3229 m a.s.l.. Areas that were not covered by Little Ice Age (LIA) glaciers have been exposed to permafrost friendly conditions. These areas are well suited for investigations aiming at the detection of permafrost evidence with a combination of methods. Geomorphological observations, geophysical measurements, like ground penetrating radar (GPR), geoelectrical soundings and refraction seismic, and airborne lasercanning (ALS) based measurements of surface changes on the study site were used to obtain an integrative analysis of possible permafrost distribution. At several small areas near the mountain ridge of the "Rofenbergköpfe" south of the glacier tongue of Hintereisferner, a small but continuous lowering of the surface was detected throughout the whole data series of 20 ALS flights. The surface changes are assumed to originate from the melting of permafrost or small dead-ice bodies. To verify this assumption, several measurements have been conducted. As electrical resistivity tomography, GPR and refraction seismic are considered as important multifunctional geophysical methods for research in periglacial and permafrost related environments, these methods were applied to detect permafrost in the areas with significant surface changes. Therefore two geophysical measurement campaigns were carried out at the "Rofenbergköpfe". The parallel application enables a comparison and cross-validation of the results gained by the three techniques. After the analyses

  17. Combining ground-based and airborne EM through Artificial Neural Networks for modelling hydrogeological units under saline groundwater conditions

    NASA Astrophysics Data System (ADS)

    Gunnink, J. L.; Bosch, J. H. A.; Siemon, B.; Roth, B.; Auken, E.

    2012-03-01

    Airborne Electro Magnetic (EM) methods supply data over large areas in a cost-effective way. We used Artificial Neural Networks (ANN) to classify the geophysical signal into a meaningful geological parameter. By using examples of known relations between ground-based geophysical data (in this case electrical conductivity, EC, from Electrical Cone Penetration Tests) and geological parameters (presence of glacial till), we extracted learning rules that could be applied to map the presence of a glacial till using the EC profiles from the airborne EM data. The saline groundwater in the area was obscuring the EC signal from the till but by using ANN we were able to extract subtle and often non-linear, relations in EC that were representative for the presence of the till. The ANN results were interpreted as the probability of having till and showed a good agreement with drilling data. The glacial till is acting as a layer that inhibits groundwater flow, due to its high clay-content, and is therefore an important layer in hydrogeological modelling and for predicting the effects of climate change on groundwater quantity and quality.

  18. Geophysical Signitures From Hydrocarbon Contaminated Aquifers

    NASA Astrophysics Data System (ADS)

    Abbas, M.; Jardani, A.

    2015-12-01

    The task of delineating the contamination plumes as well as studying their impact on the soil and groundwater biogeochemical properties is needed to support the remediation efforts and plans. Geophysical methods including electrical resistivity tomography (ERT), induced polarization (IP), ground penetrating radar (GPR), and self-potential (SP) have been previously used to characterize contaminant plumes and investigate their impact on soil and groundwater properties (Atekwana et al., 2002, 2004; Benson et al., 1997; Campbell et al., 1996; Cassidy et al., 2001; Revil et al., 2003; Werkema et al., 2000). Our objective was to: estimate the hydrocarbon contamination extent in a contaminated site in northern France, and to adverse the effects of the oil spill on the groundwater properties. We aim to find a good combination of non-intrusive and low cost methods which we can use to follow the bio-remediation process, which is planned to proceed next year. We used four geophysical methods including electrical resistivity tomography, IP, GPR, and SP. The geophysical data was compared to geochemical ones obtained from 30 boreholes installed in the site during the geophysical surveys. Our results have shown: low electrical resistivity values; high chargeability values; negative SP anomalies; and attenuated GPR reflections coincident with groundwater contamination. Laboratory and field geochemical measurements have demonstrated increased groundwater electrical conductivity and increased microbial activity associated with hydrocarbon contamination of groundwater. Our study results support the conductive model suggested by studies such as Sauck (2000) and Atekwana et al., (2004), who suggest that biological alterations of hydrocarbon contamination can substantially modify the chemical and physical properties of the subsurface, producing a dramatic shift in the geo-electrical signature from resistive to conductive. The next stage of the research will include time lapse borehole

  19. Airborne Gamma-Spectrometry in Switzerland

    NASA Astrophysics Data System (ADS)

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-01

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of 137Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  20. Airborne Gamma-Spectrometry in Switzerland

    SciTech Connect

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-07

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  1. Geophysical Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Busse, F. H.

    In the past 8 years, since Pedlosky's book was first published, it has found a well established place in the literature of dynamical meteorology and physical oceanography. Geophysicists less familiar with these fields may need to be reminded that the subject of geophysical fluid dynamics, in the narrow definition used in the title of the book, refers to the theory of the large-scale motions of the atmosphere and the oceans. Topics such as thermal convection in the atmosphere or in Earth's mantle and core are not treated in this book, and the reader will search in vain for a discussion of atmospheric or oceanic tides. The theory of quasi-geostrophic flow is described comprehensively, however, and its major applications to problems of atmospheric and oceanic circulations are considered in detail.

  2. Sampling functions for geophysics

    NASA Technical Reports Server (NTRS)

    Giacaglia, G. E. O.; Lunquist, C. A.

    1972-01-01

    A set of spherical sampling functions is defined such that they are related to spherical-harmonic functions in the same way that the sampling functions of information theory are related to sine and cosine functions. An orderly distribution of (N + 1) squared sampling points on a sphere is given, for which the (N + 1) squared spherical sampling functions span the same linear manifold as do the spherical-harmonic functions through degree N. The transformations between the spherical sampling functions and the spherical-harmonic functions are given by recurrence relations. The spherical sampling functions of two arguments are extended to three arguments and to nonspherical reference surfaces. Typical applications of this formalism to geophysical topics are sketched.

  3. Geophysics of Mars

    NASA Technical Reports Server (NTRS)

    Wells, R. A.

    1979-01-01

    A physical model of Mars is presented on the basis of light-scattering observations of the Martian atmosphere and surface and interior data obtained from observations of the geopotential field. A general description of the atmosphere is presented, with attention given to the circulation and the various cloud types, and data and questions on the blue haze-clearing effect and the seasonal darkening wave are summarized and the Mie scattering model developed to explain these observations is presented. The appearance of the planet from earth and spacecraft through Mariner 9 is considered, and attention is given to the preparation of topographical contour maps, the canal problem and large-scale lineaments observed from Mariner 9, the gravity field and shape of the planet and the application of Runcorn's geoid/convection theory to Mars. Finally, a summary of Viking results is presented and their application to the understanding of Martian geophysics is discussed.

  4. Serious games for Geophysics

    NASA Astrophysics Data System (ADS)

    Lombardo, Valerio; Rubbia, Giuliana

    2015-04-01

    Childhood stage is indispensable in the education of human beings and especially critical to arise scientific interest in children. We discuss the participatory design of a didactic videogame, i.e. a "serious" game to teach geophysics and Earth sciences to high and low-school students. Geophysics is the application of the laws and techniques of physics to uncover knowledge about the earth's dynamic processes and subsurface structure. It explores phenomena such as earthquakes, volcanoes, tsunamis to improve our understanding of the earth's physical processes and our ability to predict reoccurrences. Effective mitigation of risks from catastrophic geologic hazards requires knowledge and understanding of local geology and geologic processes. Scientific outreach can be defined as discourse activity, whose main objective is to communicate some knowledge previously produced in scientific contexts to a non-expert massive audience. One of the difficulties science educators need to overcome is to explain specific concepts from a given discipline in a language simple and understandable for their audience. Digital games today play a large role in young people's lives. Games are directly connected to the life of today's adolescents. Therefore, digital games should be included and broached as a subject in the classroom. The ardor and enthusiasm that digital games evoke in teenagers has indeed brought many researchers, school leaders and teachers to the question "how video games" can be used to engage young people and support their learning inside the classroom. Additionally, studies have shown that digital games can enhance various skills such as the ability to concentrate, stamina, tactical aptness, anticipatory thinking, orientation in virtual spaces, and deductive reasoning. Thus, videogames become an effective didactic mechanism and should have a place in the classroom. The project aims to explore the potentials of entertainment technologies in educational processes

  5. Extraction of full absorption peaks in airborne gamma-spectrometry by filtering techniques coupled with a study of the derivatives. Comparison with the window method.

    PubMed

    Guillot, L

    2001-01-01

    In this paper, an adaptation of a spectral profile analysis method, currently used in high-resolution spectrometry, to airborne gamma measurements is presented. A new algorithm has been developed for extraction of full absorption peaks by studying the variations in the spectral profile of data recorded with large-volume NaI detectors (16 l) with a short sampling time (2 s). The use of digital filters, taking into consideration the characteristics of the absorption peaks, significantly reduced the counting fluctuations, making detection possible based on study of the first and second derivatives. The absorption peaks are then obtained by modelling, followed by subtraction of the Compton continuum in the detection window. Compared to the conventional stripping ratio method, spectral profile analysis offers similar performance for the natural radioelements. The 137Cs 1SD detection limit is approximately 1200 Bq/m2 in a natural background of 200 Bq/kg 40K, 33 Bq/kg 238U and 33 Bq/kg 232Th. At low energy the very high continuum leads to detection limits similar to those obtained by the windows method, but the results obtained are more reliable. In the presence of peak overlaps, however, analysis of the spectral profile alone is not sufficient to separate the peaks, and further processing is necessary. Within the framework of environmental monitoring studies, spectral profile analysis is of great interest because it does not require any assumptions about the nature of the nuclides. The calculation of the concentrations from the results obtained is simple and reliable, since only the full absorption contributions are taken into consideration. A quantitative estimate of radioactive anomalies can thus be obtained rapidly.

  6. Archaeological Geophysics in Israel: Past, Present and Future

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.

    2009-04-01

    et al., 1999; Reeder et al., 2004; Reinhardt et al., 2006; Reich et al., 2003; Ron et al., 2003; Segal et al., 2003; Sternberg and Lass, 2007; Sternberg et al., 1999; Verri et al., 2004; Weiner et al., 1993; Weinstein-Evron et al., 1991, 2003; Weiss et al., 2007; Witten et al., 1994), and (3) future [2010 -]. The past stage with several archaeoseismic reviews and very limited application of geophysical methods was replaced by the present stage with the violent employment of numerous geophysical techniques (first of all, high-precise magnetic survey and GPR). It is supposed that the future stage will be characterized by extensive development of multidiscipline physical-archaeological databases (Eppelbaum et al., 2009b), utilization of supercomputers for 4D monitoring and ancient sites reconstruction (Foster et al., 2001; Pelfer et al., 2004) as well as wide application of geophysical surveys using remote operated vehicles at low altitudes (Eppelbaum, 2008a). REFERENCES Batey, R.A., 1987. Subsurface Interface Radar at Sepphoris, Israel 1985. Journal of Field Archaeology, 14 (1), 1-8. Bauman, P., Parker, D., Coren, A., Freund, R., and Reeder, P., 2005. Archaeological Reconnaissance at Tel Yavne, Israel: 2-D Electrical Imaging and Low Altitude Aerial Photography. CSEG Recorder, No. 6, 28-33. Ben-Dor, E., Portugali, J., Kochavi, M., Shimoni, M., and Vinitzky, L., 1999. Airborne thermal video radiometry and excavation planning at Tel Leviah, Golan Heights, Israel. Journal of Field Archaeology, 26 (2), 117-127. Ben-Menahem, A., 1979. Earthquake catalogue for the Middle East (92 B.C. - 1980 A.D.). Bollettino di Geofisica Teorica ed Applicata, 21 (84), 245-310. Ben-Yosef, E., Tauxe, L., Ronb, H., Agnon, A., Avner, U., Najjar, M., and Levy, T.E., 2008. A new approach for geomagnetic archaeointensity research: insights on ancient metallurgy in the Southern Levant. Journal of Archaeological Science, 25, 2863-2879. Berkovitch, A.L., Eppelbaum, L.V., and Basson, U., 2000

  7. Innovations In Site Characterization: Geophysical Investigation at Hazardous Waste Sites

    EPA Pesticide Factsheets

    This compendium describes a number of geophysical technologies and methods that were used at 11 sites with significantly different geological settings and types of subsurface contamination, ranging from relatively homogeneous stratigraphy to the highly ...

  8. Liquid-phase sample preparation method for real-time monitoring of airborne asbestos fibers by dual-mode high-throughput microscopy.

    PubMed

    Cho, Myoung-Ock; Kim, Jung Kyung; Han, Hwataik; Lee, Jeonghoon

    2013-01-01

    Asbestos that had been used widely as a construction material is a first-level carcinogen recognized by the World Health Organization. It can be accumulated in body by inhalation causing virulent respiratory diseases including lung cancer. In our previous study, we developed a high-throughput microscopy (HTM) system that can minimize human intervention accompanied by the conventional phase contrast microscopy (PCM) through automated counting of fibrous materials and thus significantly reduce analysis time and labor. Also, we attempted selective detection of chrysotile using DksA protein extracted from Escherichia coli through a recombinant protein production technique, and developed a dual-mode HTM (DM-HTM) by upgrading the HTM device. We demonstrated that fluorescently-labeled chrysotile asbestos fibers can be identified and enumerated automatically among other types of asbestos fibers or non-asbestos particles in a high-throughput manner through a newly modified HTM system for both reflection and fluorescence imaging. However there is a limitation to apply DM-HTM to airborne sample with current air collecting method due to the difficulty of applying the protein to dried asbestos sample. Here, we developed a technique for preparing liquid-phase asbestos sample using an impinger normally used to collect odor molecules in the air. It would be possible to improve the feasibility of the dual-mode HTM by integrating a sample preparation unit for making collected asbestos sample dispersed in a solution. The new technique developed for highly sensitive and automated asbestos detection can be a potential alternative to the conventional manual counting method, and it may be applied on site as a fast and reliable environmental monitoring tool.

  9. Assessing inhalation exposure from airborne soil contaminants

    SciTech Connect

    Shinn, J.H.

    1998-04-01

    A method of estimation of inhalation exposure to airborne soil contaminants is presented. this method is derived from studies of airborne soil particles with radioactive tags. The concentration of contaminants in air (g/m{sup 3}) can be derived from the product of M, the suspended respirable dust mass concentration (g/m{sup 3}), S, the concentration of contaminant in the soil (g/g), and E{sub f}, an enhancement factor. Typical measurement methods and values of M, and E{sub f} are given along with highlights of experiences with this method.

  10. Spectral combination of land-based, airborne, shipborne and altimeter-derived gravity values: examples in Taiwan and Tahiti

    NASA Astrophysics Data System (ADS)

    Hwang, Cheinway

    2016-04-01

    Taiwan and Tahiti are bordered by seas and are islands with mountain ranges up to 4000 m height. The gravity fields here are rough due to the geodynamic processes that create the islands. On and around the two islands, gravity data have been collected by land gravimeters in relative gravity networks (point-wise), by airborne and shipborne (along-track) methods and by transformations from sea surface heights (altimeter-derived). Typically, network-adjusted land gravity values have accuracies of few tens of micro gals and contain the full gravity spectrum. Airborne gravity values are obtained by filtering original one-HZ along-track gravity values collected at varying flight altitudes that are affected by aircraft dynamics, GPS positioning error and gravimeter error. At a 5000-m flight height, along-track airborne gravity has a typical spatial resolution of 4 km and an accuracy of few mgal. Shipborne gravity is similar to airborne gravity, but with higher spatial resolutions because of ship's lower speed. Altimeter-derived gravity has varying spatial resolutions and accuracies, depending on altimeter data, processing method and extent of waveform interference. Using the latest versions of Geosat/GM, ERS-1/GM, ENVISAT, Jason-1/GM, Cryosat-2 and SARAL altimeter data, one can achieve accuracies at few mgal. The synergy of the four kinds of gravity datasets is made by the band-limited least-squares collocation, which best integrates datasets of different accuracies and spatial resolutions. The method uses the best contributions from a DEM, a global gravity model, available gravity datasets to form an optimal gravity grid. We experiment with different optimal spherical harmonic degrees of EGM08 for use around the two islands. For Tahiti, the optimal degree is 1500. New high-resolution gravity and geoid grids are constructed for the two islands and can be used in future geophysical and geodetic studies.

  11. Characterization by electrical and electromagnetic geophysical methods of the shallow hydrogeological system at Hebron (West Bank, Palestine) in a semi-arid zone

    NASA Astrophysics Data System (ADS)

    Sirhan, Asal; Hamidi, Mohammad O.

    2012-09-01

    Multi-electrode geo-electrical and transient electromagnetic surveys were carried out to characterize the nature of the subsurface infiltration zones (5 to 20 m) related to a series of groundwater outlets, and to reveal the geometry of the different aquifers at Bani-Naim, in the south-eastern foothills of the Hebron area, West Bank, Palestine. The purpose of the surveys was to understand the link between water storage/transfer and the characteristics of the geological formations. The strata in this semi-arid region are composed of alternate layers of chalky limestone, hard limestone, marl and chalk. A total of 30 ERT and 15 TDEM were conducted at Bani Naim-Jahir and Bani Naim-Birein. A correlation between the results indicates various infiltration pathways: fractures, feature heterogeneities, and porous chalk. The local heterogeneity on the eastern side were the major pathways for the water infiltration, whereas the thick marl layer underneath acts as a natural impermeable barrier preventing water from infiltrating deeper. A combination of the different geophysical results identified conductive features that correspond to the infiltration zones supplying the dug wells with water. Furthermore, it was established that the fractured chalk and porous chalky limestone act as an aquifer. A three-dimensional visualization of the resistivity allowed a useful reconstruction of the shallow hydrogeological system. Consequently, these studies contribute to regional sustainable development projects in this semi-arid region.

  12. Installation restoration research program: Assessment of geophysical methods for subsurface geologic mapping, cluster 13, Edgewood Area, Aberdeen Proving Ground, Maryland. Final report

    SciTech Connect

    Butler, D.K.; Sharp, M.K.; Sjostrom, K.J.; Simms, J.E.; Llopis, J.L.

    1996-10-01

    Seismic refraction, electrical resistivity, and transient electromagnetic surveys were conducted at a portion of Cluster 13, Edgewood Area of Aberdeen Proving Ground, Maryland. Seismic refraction cross sections map the topsoil layer and the water table (saturated zone). The water table elevations from the seismic surveys correlate closely with water table elevations in nearby monitoring wells. Electrical resistivity cross sections reveal a very complicated distribution of sandy and clayey facies in the upper 10 - 15 m of the subsurface. A continuous surficial (topsoil) layer correlates with the surficial layer of the seismic section and nearby boring logs. The complexity and details of the electrical resistivity cross section correlate well with boring and geophysical logs from nearby wells. The transient electromagnetic surveys map the Pleistocene-Cretaceous boundary, the saprolite, and the top of the Precambrian crystalline rocks. Conducting the transient electromagnetic surveys on a grid pattern allows the construction of a three-dimensional representation of subsurface geology (as represented by variations of electrical resistivity). Thickness and depth of the saprolitic layer and depth to top of the Precambrian rocks are consistent with generalized geologic cross sections for the Edgewood Area and depths projected from reported depths at the Aberdeen Proving Ground NW boundary using regional dips.

  13. Jesuit Geophysical Observatories

    NASA Astrophysics Data System (ADS)

    Udias, Agustin; Stauder, William

    Jesuits have had ah interest in observing and explaining geophysical phenomena since this religious order, the Society of Jesus, was founded by Ignatius of Loyola in 1540. Three principal factors contributed to this interest: their educational work in colleges and universities, their missionary endeavors to remote lands where they observed interesting and often as yet undocumented natural phenomena, and a network of communication that brought research of other Jesuits readily to their awareness.One of the first and most important Jesuit colleges was the Roman College (today the Gregorian University) founded in 1551 in Rome, which served as a model for many other universities throughout the world. By 1572, Christopher Clavius (1537-1612), professor of mathematics at the Roman College, had already initiated an important tradition of Jesuit research by emphasizing applied mathematics and insisting on the need of serious study of mathematics in the program of studies in the humanities. In 1547 he directed a publication of Euclid's work with commentaries, and published several treatises on mathematics, including Arithmetica Practica [1585], Gnomonicae [1581], and Geometrica Practica [1606]. Clavius was also a Copernican and supported his friend Galileo when he announced the discovery of the satellites of Jupiter.

  14. A ``model`` geophysics program

    SciTech Connect

    Nyquist, J.E.

    1994-03-01

    In 1993, I tested a radio-controlled airplane designed by Jim Walker of Brigham Young University for low-elevation aerial photography. Model-air photography retains most of the advantages of standard aerial photography --- the photographs can be used to detect lineaments, to map roads and buildings, and to construct stereo pairs to measure topography --- and it is far less expensive. Proven applications on the Oak Ridge Reservation include: updating older aerial records to document new construction; using repeated overflights of the same area to capture seasonal changes in vegetation and the effects of major storms; and detecting waste trench boundaries from the color and character of the overlying grass. Aerial photography is only one of many possible applications of radio-controlled aircraft. Currently, I am funded by the Department of Energy`s Office of Technology Development to review the state of the art in microavionics, both military and civilian, to determine ways this emerging technology can be used for environmental site characterization. Being particularly interested in geophysical applications, I am also collaborating with electrical engineers at Oak Ridge National Laboratory to design a model plane that will carry a 3-component flux-gate magnetometer and a global positioning system, which I hope to test in the spring of 1994.

  15. EDITORIAL: Integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage Integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage

    NASA Astrophysics Data System (ADS)

    Masini, N.; Soldovieri, F.

    2011-09-01

    In the last two decades, the use of non-invasive methods for the study and conservation of cultural heritage, from artefacts and historical sites to recent architectural structures, has gained increasing interest. This is due to several reasons: (i) the improvement of performance and information resolution of sensors and devices; (ii) the increasing availability of user-friendly data/image analysis, and processing software and routines; (iii) the ever greater awareness of archaeologists and conservators of the benefits of these technologies, in terms of reduction of costs, time and the risk associated with direct and destructive investigations of archaeological sites (excavation) and monuments (i.e. masonry coring). The choice of diagnostic strategy depends on the spatial and physical characteristics of the cultural objects or sites, the aim of the investigation (knowledge, conservation, restoration) and the issues to be addressed (monitoring, decay assessment, etc). This makes the set up and validation of ad hoc procedures based on data processing and post-processing methods necessary, generally developed to address issues in other fields of application. This methodological perspective based on an integrated and multi-scale approach characterizes the papers of this special issue, which is focused on integrated non-invasive sensing techniques and geophysical methods for the study and conservation of architectural, archaeological and artistic heritage. In particular, attention is given to the advanced application of the synthetic aperture radar (SAR) from the satellite-based platform for deformation monitoring thanks to the innovative differential SAR interferometry (DInSAR) technique; Zeni et al show the significant possibilities of the proposed methodology in achieving a global vision not only of cultural heritage but also of the embedding territory. This collection also deals with the application of non-invasive diagnostics to archaeological prospecting, and

  16. Aerosol, surface, and cloud optical parameters derived from airborne spectral actinic flux: measurement comparison with other methods

    NASA Astrophysics Data System (ADS)

    Stark, H.; Bierwirth, E.; Schmidt, S.; Kindel, B. C.; Pilewskie, P.; Lack, D. A.; Madronich, S.; Parrish, D. D.

    2009-12-01

    Optical parameters of aerosols, surfaces, and clouds are essential for an accurate description of Earth’s radiative balance. We will present values for such parameters derived from spectral actinic flux measured on board the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in April 2008. We will compare these measurements to results obtained from other instruments on board the same aircraft, such as the Solar Spectral Flux Radiometer (SSFR) for irradiance measurements and aerosol extinction and absorption measurements by cavity ring-down and Particle Soot Absorption Photometer (PSAP). Actinic flux is sensitive to these parameters and can be used to measure them directly in the atmosphere without in-situ sampling methods required. We will describe the specifics of the actinic flux measurements, show advantages and disadvantages of this measurement technique, and compare results with other techniques. Furthermore, we will compare our measurements with model calculations from radiative transfer models such as the Tropospheric Ultraviolet and Visible (TUV) radiation model, the widely used library of radiative transfer (libradtran) model, and a Monte-Carlo radiation model (GRIMALDI). Also, we will investigate satellite measurements to constrain the radiation measurements to general radiation conditions in the arctic and to compare the results to aerosol optical depth retrievals. In particular, we will show results for surface albedo of the Arctic Ocean ice surface, extinction and absorption of Arctic haze layers, and optical thickness and albedo measurements of clouds.

  17. Application of Surface Geophysical Methods, With Emphasis on Magnetic Resonance Soundings, to Characterize the Hydrostratigraphy of the Brazos River Alluvium Aquifer, College Station, Texas, July 2006 - A Pilot Study

    USGS Publications Warehouse

    Shah, Sachin D.; Kress, Wade H.; Legchenko, Anatoly

    2007-01-01

    The U.S. Geological Survey, in cooperation with the Texas Water Development Board, used surface geophysical methods at the Texas A&M University Brazos River Hydrologic Field Research Site near College Station, Texas, in a pilot study, to characterize the hydrostratigraphic properties of the Brazos River alluvium aquifer and determine the effectiveness of the methods to aid in generating an improved ground-water availability model. Three non-invasive surface geophysical methods were used to characterize the electrical stratigraphy and hydraulic properties and to interpret the hydrostratigraphy of the Brazos River alluvium aquifer. Two methods, time-domain electromagnetic (TDEM) soundings and two-dimensional direct-current (2D-DC) resistivity imaging, were used to define the lateral and vertical extent of the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the underlying Yegua Formation. Magnetic resonance sounding (MRS), a recently developed geophysical method, was used to derive estimates of the hydrologic properties including percentage water content and hydraulic conductivity. Results from the geophysics study demonstrated the usefulness of combined TDEM, 2D-DC resistivity, and MRS methods to reduce the need for additional boreholes in areas with data gaps and to provide more accurate information for ground-water availability models. Stratigraphically, the principal finding of this study is the relation between electrical resistivity and the depth and thickness of the subsurface hydrostratigraphic units at the site. TDEM data defined a three-layer electrical stratigraphy corresponding to a conductor-resistor-conductor that represents the hydrostratigraphic units - the Ships clay, the alluvium of the Brazos River alluvium aquifer, and the Yegua Formation. Sharp electrical boundaries occur at about 4 to 6 and 20 to 22 meters below land surface based on the TDEM data and define the geometry of the more resistive Brazos River alluvium aquifer

  18. Retrieval of Atmospheric Temperature from Airborne Microwave Radiometer Observations

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Schreier, Franz; Kenntner, Mareike; Fix, Andreas; Trautmann, Thomas

    2015-11-01

    Atmospheric temperature is a key geophysical parameter associated with fields such as meteorology, climatology, or photochemistry. There exist several techniques to measure temperature profiles. In the case of microwave remote sensing, the vertical temperature profile can be estimated from thermal emission lines of molecular oxygen. The MTP (Microwave Temperature Profiler) instrument is an airborne radiometer developed at the Jet Propulsion Laboratory (JPL), United States. The instrument passively measures natural thermal emission from oxygen lines at 3 frequencies and at a selection of 10 viewing angles (from near zenith to near nadir). MTP has participated in hundreds of flights, including on DLR's Falcon and HALO aircrafts. These flights have provided data of the vertical temperature distribution from the troposphere to the lower stratosphere with a good temporal and spatial resolution. In this work, we present temperature retrievals based on the Tikhonov-type regularized nonlinear least squares fitting method. In particular, Jacobians (i.e. temperature derivatives) are evaluated by means of automatic differentiation. The retrieval performance from the MTP measurements is analyzed by using synthetic data. Besides, the vertical sensitivity of the temperature retrieval is studied by weighting functions characterizing the sensitivity of the transmission at different frequencies with respect to changes of altitude levels.

  19. Inversion Algorithms for Geophysical Problems

    DTIC Science & Technology

    1987-12-16

    ktdud* Sccumy Oass/Kjoon) Inversion Algorithms for Geophysical Problems (U) 12. PERSONAL AUTHOR(S) Lanzano, Paolo 13 «. TYPE OF REPORT Final 13b...spectral density. 20. DISTRIBUTION/AVAILABILITY OF ABSTRACT 13 UNCLASSIFIED/UNLIMITED D SAME AS RPT n OTIC USERS 22a. NAME OF RESPONSIBLE...Research Laboratory ’^^ SSZ ’.Washington. DC 20375-5000 NRLrMemorandum Report-6138 Inversion Algorithms for Geophysical Problems p. LANZANO Space

  20. Marine Geophysics: a Navy Symposium

    DTIC Science & Technology

    1987-09-01

    post-docs are now the current leaders in marine geology and geophysics, not only in the United States but also in Britain, France, and Australia ...to make it fun both for themselves and for others was the keystone of the success of the marine geology and geophysics program at Scripps. They, with...G. G. Shor, Jr., R. W. Raitt, and M. Henry. 1977. Seismic refraction and reflection studies of crustal structure of the eastern Sunda and western

  1. Evaluating airborne and ground based gamma spectrometry methods for detecting particulate radioactivity in the environment: a case study of Irish Sea beaches.

    PubMed

    Cresswell, A J; Sanderson, D C W

    2012-10-15

    In several places, programmes are in place to locate and recover radioactive particles that have the potential to cause detrimental health effects in any member of the public who may encounter them. A model has been developed to evaluate the use of mobile gamma spectrometry systems within such programmes, with particular emphasis on large volume (16l) NaI(Tl) detectors mounted in low flying helicopters. This model uses a validated Monte Carlo code with assessment of local geochemistry and natural and anthropogenic background radiation concentrations and distributions. The results of the model, applied to the example of particles recovered from beaches in the vicinity of Sellafield, clearly show the ability of rapid airborne surveys conducted at 75 m ground clearance and 120 kph speeds to demonstrate the absence of sources greater than 5 MBq (137)Cs within large areas (10-20 km(2)h(-1)), and identify areas requiring further ground based investigation. Lowering ground clearance for airborne surveys to 15m whilst maintaining speeds covering 1-2 km(2) h(-1) can detect buried (137)Cs sources of 0.5MBq or greater activity. A survey design to detect 100 kBq (137)Cs sources at 10 cm depth has also been defined, requiring surveys at <15m ground clearance and <2 ms(-1) ground speed. The response of airborne systems to the Sellafield particles recovered to date has also been simulated, and the proportion of the existing radiocaesium background in the vicinity of the nuclear site has been established. Finally the rates of area coverage and sensitivities of both airborne and ground based approaches are compared, demonstrating the ability of airborne systems to increase the rate of particle recovery in a cost effective manner. The potential for equipment and methodological developments to improve performance are discussed.

  2. Planetary Geophysics and Tectonics

    NASA Technical Reports Server (NTRS)

    Zuber, Maria

    2005-01-01

    The broad objective of this work is to improve understanding of the internal structures and thermal and stress histories of the solid planets by combining results from analytical and computational modeling, and geophysical data analysis of gravity, topography and tectonic surface structures. During the past year we performed two quite independent studies in the attempt to explain the Mariner 10 magnetic observations of Mercury. In the first we revisited the possibility of crustal remanence by studying the conditions under which one could break symmetry inherent in Runcorn's model of a uniformly magnetized shell to produce a remanent signal with a dipolar form. In the second we applied a thin shell dynamo model to evaluate the range of intensity/structure for which such a planetary configuration can produce a dipole field consistent with Mariner 10 results. In the next full proposal cycle we will: (1) develop numerical and analytical and models of thin shell dynamos to address the possible nature of Mercury s present-day magnetic field and the demise of Mars magnetic field; (2) study the effect of degree-1 mantle convection on a core dynamo as relevant to the early magnetic field of Mars; (3) develop models of how the deep mantles of terrestrial planets are perturbed by large impacts and address the consequences for mantle evolution; (4) study the structure, compensation, state of stress, and viscous relaxation of lunar basins, and address implications for the Moon s state of stress and thermal history by modeling and gravity/topography analysis; and (5) use a three-dimensional viscous relaxation model for a planet with generalized vertical viscosity distribution to study the degree-two components of the Moon's topography and gravity fields to constrain the primordial stress state and spatial heterogeneity of the crust and mantle.

  3. Airborne Crowd Density Estimation

    NASA Astrophysics Data System (ADS)

    Meynberg, O.; Kuschk, G.

    2013-10-01

    This paper proposes a new method for estimating human crowd densities from aerial imagery. Applications benefiting from an accurate crowd monitoring system are mainly found in the security sector. Normally crowd density estimation is done through in-situ camera systems mounted on high locations although this is not appropriate in case of very large crowds with thousands of people. Using airborne camera systems in these scenarios is a new research topic. Our method uses a preliminary filtering of the whole image space by suitable and fast interest point detection resulting in a number of image regions, possibly containing human crowds. Validation of these candidates is done by transforming the corresponding image patches into a low-dimensional and discriminative feature space and classifying the results using a support vector machine (SVM). The feature space is spanned by texture features computed by applying a Gabor filter bank with varying scale and orientation to the image patches. For evaluation, we use 5 different image datasets acquired by the 3K+ aerial camera system of the German Aerospace Center during real mass events like concerts or football games. To evaluate the robustness and generality of our method, these datasets are taken from different flight heights between 800 m and 1500 m above ground (keeping a fixed focal length) and varying daylight and shadow conditions. The results of our crowd density estimation are evaluated against a reference data set obtained by manually labeling tens of thousands individual persons in the corresponding datasets and show that our method is able to estimate human crowd densities in challenging realistic scenarios.

  4. Using geophysics to characterize levee stability

    NASA Astrophysics Data System (ADS)

    Dalton, Laura M.

    Shallow slough slides have occurred along the river side slope of Mississippi River Levees for over sixty years. Shallow slough slides also occur along smaller levees that protect tributaries of the Mississippi River. This investigation takes place along a section of the Coldwater River Levee, a tributary levee of the Mississippi River. Field observation, soil samples, and geophysical data were collected at two field sites located on the border of Tate and Tunica County, MS. The first site consists of a developed shallow slough slide that had occurred that has not yet been repaired and the second site is a potential slide area. Electromagnetic induction and electrical resistivity tomography were the geophysical methods used to define subsurface conditions that make a levee vulnerable to failure. These electrical methods are sensitive to the electrical conductivity of the soil and therefore depend upon: soil moisture, clay content, pore size distribution as well as larger scale structures at depth such as cracks and fissures. These same physical properties of the soil are also important to assessing the vulnerability of a levee to slough slides. Soil tests and field observations were also implemented in this investigation to describe and classify the soil composition of the levee material. The problem of slough slide occurrence can potentially be reduced if vulnerabilities are located with the help of geophysical techniques.

  5. Enumerating Spore-Forming Bacteria Airborne with Particles

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Barengoltz, Jack

    2006-01-01

    A laboratory method has been conceived to enable the enumeration of (1) Cultivable bacteria and bacterial spores that are, variously, airborne by themselves or carried by, parts of, or otherwise associated with, other airborne particles; and (2) Spore-forming bacteria among all of the aforementioned cultivable microbes.

  6. NASA Airborne Science Program: NASA Stratospheric Platforms

    NASA Technical Reports Server (NTRS)

    Curry, Robert E.

    2010-01-01

    The National Aeronautics and Space Administration conducts a wide variety of remote sensing projects using several unique aircraft platforms. These vehicles have been selected and modified to provide capabilities that are particularly important for geophysical research, in particular, routine access to very high altitudes, long range, long endurance, precise trajectory control, and the payload capacity to operate multiple, diverse instruments concurrently. While the NASA program has been in operation for over 30 years, new aircraft and technological advances that will expand the capabilities for airborne observation are continually being assessed and implemented. This presentation will review the current state of NASA's science platforms, recent improvements and new missions concepts as well as provide a survey of emerging technologies unmanned aerial vehicles for long duration observations (Global Hawk and Predator). Applications of information technology that allow more efficient use of flight time and the ability to rapidly reconfigure systems for different mission objectives are addressed.

  7. Airborne gravimetry, altimetry, and GPS navigation errors

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.

    1992-01-01

    Proper interpretation of airborne gravimetry and altimetry requires good knowledge of aircraft trajectory. Recent advances in precise navigation with differential GPS have made it possible to measure gravity from the air with accuracies of a few milligals, and to obtain altimeter profiles of terrain or sea surface correct to one decimeter. These developments are opening otherwise inaccessible regions to detailed geophysical mapping. Navigation with GPS presents some problems that grow worse with increasing distance from a fixed receiver: the effect of errors in tropospheric refraction correction, GPS ephemerides, and the coordinates of the fixed receivers. Ionospheric refraction and orbit error complicate ambiguity resolution. Optimal navigation should treat all error sources as unknowns, together with the instantaneous vehicle position. To do so, fast and reliable numerical techniques are needed: efficient and stable Kalman filter-smoother algorithms, together with data compression and, sometimes, the use of simplified dynamics.

  8. Airborne Next: Rethinking Airborne Organization and Applying New Concepts

    DTIC Science & Technology

    2015-06-01

    structures since its employment on a large scale during World War II. It is puzzling to consider how little airborne organizational structures and employment...future potential of airborne concepts by rethinking traditional airborne organizational structures and employment concepts. Using a holistic approach in... structures of airborne forces to model a “small and many” approach over a “large and few” approach, while incorporating a “swarming” concept. Utilizing

  9. Geophysical applications for levee assessment

    NASA Astrophysics Data System (ADS)

    Chlaib, Hussein Khalefa

    Levees are important engineering structures that build along the rivers to protect the human lives and shield the communities as well as agriculture lands from the high water level events. Animal burrows, subsurface cavities, and low density (high permeability) zones are weakness features within the levee body that increase its risk of failure. To prevent such failure, continuous monitoring of the structure integrity and early detection of the weakness features must be conducted. Application of Ground Penetrating Radar (GPR) and Capacitively Coupled Resistivity (CCR) methods were found to be very effective in assessing the levees and detect zones of weakness within the levee body. GPR was implemented using multi-frequency antennas (200, 400, and 900 MHz) with survey cart/wheel and survey vehicle. The (CCR) method was applied by using a single transmitter and three receivers. Studying the capability and the effectiveness of these methods in levee monitoring, subsurface weakness feature detection, and studying the structure integrity of levees were the main tasks of this dissertation. A set of laboratory experiments was conducted at the Geophysics Laboratory of the University of Arkansas at Little Rock (UALR) to analyze the polarity change in GPR signals in the presence of subsurface voids and water-filled cavities. Also three full scale field expeditions at the Big Dam Bridge (BDB) Levee, Lollie Levee, and Helena Levee in Arkansas were conducted using the GPR technique. This technique was effective in detecting empty, water, and clay filled cavities as well as small scale animal burrows (small rodents). The geophysical work at BDB and Lollie Levees expressed intensive subsurface anomalies which might decrease their integrity while the Helena Levee shows less subsurface anomalies. The compaction of levee material is a key factor affecting piping phenomenon. The structural integrity of the levee partially depends on the density/compaction of the soil layers. A

  10. Biological monitoring of airborne pollution

    SciTech Connect

    Ditz, D.W. )

    1990-01-01

    Common plants such as grasses, mosses, and even goldenrod may turn out to have a new high-tech role as monitors of airborne pollution from solid waste incinerators. Certain plants that respond to specific pollutants can provide continuous surveillance of air quality over long periods of time: they are bio-indicators. Other species accumulate pollutants and can serve as sensitive indicators of pollutants and of food-chain contamination: they are bio-accumulators. Through creative use of these properties, biological monitoring can provide information that cannot be obtained by current methods such as stack testing.

  11. SAGE celebrates 25 years of learning geophysics by doing geophysics

    USGS Publications Warehouse

    Jiracek, G.R.; Baldridge, W.S.; Sussman, A.J.; Biehler, S.; Braile, L.W.; Ferguson, J.F.; Gilpin, B.E.; McPhee, D.K.; Pellerin, L.

    2008-01-01

    The increasing world demand and record-high costs for energy and mineral resources, along with the attendant environmental and climate concerns, have escalated the need for trained geophysicists to unprecedented levels. This is not only a national need; it's a critical global need. As Earth scientists and educators we must seriously ask if our geophysics pipeline can adequately address this crisis. One program that has helped to answer this question in the affirmative for 25 years is SAGE (Summer of Applied Geophysical Experience). SAGE continues to develop with new faculty, new collaborations, and additional ways to support student participation during and after SAGE. ?? 2008 Society of Exploration Geophysicists.

  12. Geophysical mapping of solution and collapse sinkholes

    NASA Astrophysics Data System (ADS)

    Kaufmann, Georg

    2014-12-01

    Karst rocks such as limestone, dolomite, anhydrite, gypsum, or salt can be dissolved physically by water or chemically by water enriched with carbon dioxide. The dissolution is driven by water flowing through the karst aquifer and either occurs along fractures and bedding partings in telogenetic rocks, or within the primary interconnected pore space in eogenetic rocks. The enlargement of either fractures or pores by dissolution creates a large secondary porosity typical of soluble rocks, which is often very heterogenously distributed and results in preferential flow paths in the sub-surface, with cavities as large-scale end members of the sub-surface voids. Once the sub-surface voids enlarged by dissolution grow to a certain size, the overburden rock can become unstable and voids and caves can collapse. Depending on the type of overburden, the collapse initiated at depth may propagate towards the surface and finally results at the surface as collapse sinkholes and tiangkengs on the very large scale. We present results from geophysical surveys over existing karst structures based on gravimetric, electrical, and geomagnetical methods. We have chosen two types of sinkholes, solution and collapse sinkholes, to capture and compare the geophysical signals resulting from these karst structures. We compare and discuss our geophysical survey results with simplified theoretical models describing the evolution of the karst structure, and we derive three-dimensional structural models of the current situation for the different locations with our numerical tool PREDICTOR.

  13. Transport and formation processes for fine airborne ash from three recent volcanic eruptions in Alaska: Implications for detection methods and tracking models

    NASA Astrophysics Data System (ADS)

    Rinkleff, Peter G.

    Airborne fine volcanic ash was collected during the eruptions of Augustine Volcano in 2006, Pavlof Volcano in 2007, and Redoubt Volcano in 2009 using Davis Rotating Unit for Measurement (DRUM) cascade impactors to observe atmospheric processes acting on ash as an atmospheric particle. During the Redoubt eruption, samples were also collected by Beta Attenuation Mass (BAM-1020) and Environmental Beta Attenuation Mass (EBAM) monitors. BAM-1020s and EBAMs provided real-time mass concentration data; DRUM samplers provided samples for post-eruptive analysis. DRUM samples were retrospectively analyzed for time-resolved mass concentration and chemistry. EBAM and BAM-1020s reported near real-time, time-resolved mass concentrations. Scanning Electron Microscopy with Energy Dispersive Spectroscopy was conducted to determine particle size, shape, and composition. Image processing methods were developed to determine particle size distributions and shape factors. Ash occurred as single grains, ash aggregates, and hybrid aggregates. Ash aggregates occurred in plumes from pyroclastic flows and were found in a discrete aerodynamic size range (2.5-1.15 µm). Hybrid ash was common in all samples and likely formed when downward mixing ash mingled with upward mixing sea salt and non-sea salt sulfate. The mass concentration of sulfate did not vary systematically with ash which indicated that the source of sulfate was not necessarily volcanic. Ash size distributions were log-normal. Size distribution plots of ash collected from the same plume at different transport distances showed that longer atmospheric residence times allowed for more aggregation to occur which led to larger but fewer particles in the plume the longer it was transported. Ash transport and dispersion models forecasted ash fall over a broad area, but ash fall was only observed in areas unaffected by topographic barriers. PM10 (particulates ≤ 10 µm in aerodynamic diameter or ØA) ash was detected closer to the volcano

  14. Geophysical Monitoring of Soil Stabilization Processes

    NASA Astrophysics Data System (ADS)

    Saneiyan, S.; Ntarlagiannis, D.; Werkema, D. D., Jr.

    2015-12-01

    Rapid growth of population led to the need of urban expansion into lands with problematic soils. For safe land development, the stability of problematic soils has to be enhanced. Among the many methods utilized, microbial induced carbonate precipitation (MICP) is of particular interest as a low energy, cost efficient and potentially long term ground improvement technique. As with other soil improvement methods though, high resolution temporal and spatial monitoring methods are missing. Geophysical methods can fill that gap, by efficiently complementing and extending current monitoring practices. Geophysical methods can offer low cost, no intrusive, continuous and spatially extensive monitoring of ground improvement techniques. With this work we test two of the most promising methods for monitoring MICP, Spectral Induced Polarization (SIP) and Nuclear Magnetic Resonance (NMR); additionally, we performed shear wave velocity measurements - the established standard on soil strength characterization - for direct comparison with NMR and SIP. The tests were performed in columns filled with unconsolidated porous media (e.g. Ottawa sand, glass beads) while binding was promoted with the addition of calcite. For the first part of the experiment we used abiotic methods for Calcite formation, while the second part involves microbial induced processes. The objective of this work is to quantify the sensitivity of NMR and SIP on soil strengthening as a result of calcite precipitation. Early results suggest that both methods, SIP and NMR, are sensitive calcite precipitation and dissolution processes.

  15. Urban greenness influences airborne bacterial community composition.

    PubMed

    Mhuireach, Gwynne; Johnson, Bart R; Altrichter, Adam E; Ladau, Joshua; Meadow, James F; Pollard, Katherine S; Green, Jessica L

    2016-11-15

    Urban green space provides health benefits for city dwellers, and new evidence suggests that microorganisms associated with soil and vegetation could play a role. While airborne microorganisms are ubiquitous in urban areas, the influence of nearby vegetation on airborne microbial communities remains poorly understood. We examined airborne microbial communities in parks and parking lots in Eugene, Oregon, using high-throughput sequencing of the bacterial 16S rRNA gene on the Illumina MiSeq platform to identify bacterial taxa, and GIS to measure vegetation cover in buffer zones of different diameters. Our goal was to explore variation among highly vegetated (parks) versus non-vegetated (parking lots) urban environments. A secondary objective was to evaluate passive versus active collection methods for outdoor airborne microbial sampling. Airborne bacterial communities from five parks were different from those of five parking lots (p=0.023), although alpha diversity was similar. Direct gradient analysis showed that the proportion of vegetated area within a 50m radius of the sampling station explained 15% of the variation in bacterial community composition. A number of key taxa, including several Acidobacteriaceae were substantially more abundant in parks, while parking lots had higher relative abundance of Acetobacteraceae. Parks had greater beta diversity than parking lots, i.e. individual parks were characterized by unique bacterial signatures, whereas parking lot communities tended to be similar to each other. Although parks and parking lots were selected to form pairs of nearby sites, spatial proximity did not appear to affect compositional similarity. Our results also showed that passive and active collection methods gave comparable results, indicating the "settling dish" method is effective for outdoor airborne sampling. This work sets a foundation for understanding how urban vegetation may impact microbial communities, with potential implications for designing

  16. Object Storage for Geophysical Data

    NASA Astrophysics Data System (ADS)

    Habermann, T.; Readey, J.

    2015-12-01

    Object storage systems (such as Amazon S3 or Ceph) have been shown to be cost-effective and highly scalable for data repositories in the Petabyte range and larger. However traditionally data storage used for geophysical software systems has centered on file-based systems and libraries such as NetCDF and HDF5. In this session we'll discuss the advantages and challenges of moving to an object store-based model for geophysical data. We'll review a proposed model for a geophysical data service that provides an API-compatible library for traditional NetCDF and HDF5 applications while providing high scalability and performance. One further advantage of this approach is that any dataset or dataset selection can be referenced as a URI. By using versioning, the data the URI references can be guaranteed to be unmodified, thus enabling reproducibility of referenced data.

  17. Initial Retrieval Validation from the Joint Airborne IASI Validation Experiment (JAIVEx)

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Liu, Xu; Smith, WIlliam L.; Larar, Allen M.; Taylor, Jonathan P.; Revercomb, Henry E.; Mango, Stephen A.; Schluessel, Peter; Calbet, Xavier

    2007-01-01

    The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite, but also included a strong component focusing on validation of the Atmospheric InfraRed Sounder (AIRS) aboard the AQUA satellite. The cross validation of IASI and AIRS is important for the joint use of their data in the global Numerical Weather Prediction process. Initial inter-comparisons of geophysical products have been conducted from different aspects, such as using different measurements from airborne ultraspectral Fourier transform spectrometers (specifically, the NPOESS Airborne Sounder Testbed Interferometer (NAST-I) and the Scanning-High resolution Interferometer Sounder (S-HIS) aboard the NASA WB-57 aircraft), UK Facility for Airborne Atmospheric Measurements (FAAM) BAe146-301 aircraft insitu instruments, dedicated dropsondes, radiosondes, and ground based Raman Lidar. An overview of the JAIVEx retrieval validation plan and some initial results of this field campaign are presented.

  18. Cluster analysis applied to multiparameter geophysical dataset

    NASA Astrophysics Data System (ADS)

    Di Giuseppe, M. G.; Troiano, A.; Troise, C.; De Natale, G.

    2012-04-01

    . Vesuvius area. In all these application, cluster analysis integrating distinct geophysical methods appears an effective method to characterize complex geologic settings. Our post inversion clustering approach could possibly be applied at different of investigation scales, geophysical datasets, in many fields of geophysical exploration, where quantitative analysis of multiparameter geophysical information data is the key to successful implementation.

  19. Regional scale groundwater resource assessment in the Australian outback - Geophysics is the only way.

    NASA Astrophysics Data System (ADS)

    Munday, T. J.; Davis, A. C.; Gilfedder, M.; Annetts, D.

    2015-12-01

    Resource development, whether in agriculture, mining and/or energy, is set to have significant consequences for the groundwater resources of Australia in the short to medium term. These industry sectors are of significant economic value to the country and consequently their support remains a priority for State and Federal Governments alike. The scale of potential developments facilitated in large part by the Government Programs, like the West Australian (WA) Government's "Water for Food" program, and the South Australian's Government's PACE program, will result in an increase in infrastructure requirements, including access to water resources and Aboriginal lands to support these developments. However, the increased demand for water, particularly groundwater, is likely to be compromised by the limited information we have about these resources. This is particularly so for remote parts of the country which are targeted as primary development areas. There is a recognised need to expand this knowledge so that water availability is not a limiting factor to development. Governments of all persuasions have therefore adopted geophysical technologies, particularly airborne electromagnetics (AEM), as a basis for extending the hydrogeological knowledge of data poor areas. In WA, the State Government has employed regional-scale AEM surveys as a basis for defining groundwater resources to support mining, regional agricultural developments whilst aiming to safeguard regional population centres, and environmental assets. A similar approach is being employed in South Australia. These surveys are being used to underpin conceptual hydrogeological frameworks, define basin-scale hydrogeological models, delimit the extent of saltwater intrusion in coastal areas, and to determine the groundwater resource potential of remote alluvial systems aimed at supporting new, irrigation-based, agricultural developments in arid parts of the Australian outback. In the absence of conventional

  20. GTE: a new FFT based software to compute terrain correction on airborne gravity surveys in spherical approximation.

    NASA Astrophysics Data System (ADS)

    Capponi, Martina; Sampietro, Daniele; Sansò, Fernando

    2016-04-01

    The computation of the vertical attraction due to the topographic masses (Terrain Correction) is still a matter of study both in geodetic as well as in geophysical applications. In fact it is required in high precision geoid estimation by the remove-restore technique and it is used to isolate the gravitational effect of anomalous masses in geophysical exploration. This topographical effect can be evaluated from the knowledge of a Digital Terrain Model in different ways: e.g. by means of numerical integration, by prisms, tesseroids, polyedra or Fast Fourier Transform (FFT) techniques. The increasing resolution of recently developed digital terrain models, the increasing number of observation points due to extensive use of airborne gravimetry and the increasing accuracy of gravity data represents nowadays major issues for the terrain correction computation. Classical methods such as prism or point masses approximations are indeed too slow while Fourier based techniques are usually too approximate for the required accuracy. In this work a new software, called Gravity Terrain Effects (GTE), developed in order to guarantee high accuracy and fast computation of terrain corrections is presented. GTE has been thought expressly for geophysical applications allowing the computation not only of the effect of topographic and bathymetric masses but also those due to sedimentary layers or to the Earth crust-mantle discontinuity (the so called Moho). In the present contribution we summarize the basic theory of the software and its practical implementation. Basically the GTE software is based on a new algorithm which, by exploiting the properties of the Fast Fourier Transform, allows to quickly compute the terrain correction, in spherical approximation, at ground or airborne level. Some tests to prove its performances are also described showing GTE capability to compute high accurate terrain corrections in a very short time. Results obtained for a real airborne survey with GTE

  1. Airborne Remote Sensing

    NASA Technical Reports Server (NTRS)

    1992-01-01

    NASA imaging technology has provided the basis for a commercial agricultural reconnaissance service. AG-RECON furnishes information from airborne sensors, aerial photographs and satellite and ground databases to farmers, foresters, geologists, etc. This service produces color "maps" of Earth conditions, which enable clients to detect crop color changes or temperature changes that may indicate fire damage or pest stress problems.

  2. Recognizing Airborne Hazards.

    ERIC Educational Resources Information Center

    Schneider, Christian M.

    1990-01-01

    The heating, ventilating, and air conditioning (HVAC) systems in older buildings often do not adequately handle air-borne contaminants. Outlines a three-stage Indoor Air Quality (IAQ) assessment and describes a case in point at a Pittsburgh, Pennsylvania, school. (MLF)

  3. Airborne asbestos in buildings.

    PubMed

    Lee, R J; Van Orden, D R

    2008-03-01

    The concentration of airborne asbestos in buildings nationwide is reported in this study. A total of 3978 indoor samples from 752 buildings, representing nearly 32 man-years of sampling, have been analyzed by transmission electron microscopy. The buildings that were surveyed were the subject of litigation related to suits alleging the general building occupants were exposed to a potential health hazard as a result the presence of asbestos-containing materials (ACM). The average concentration of all airborne asbestos structures was 0.01structures/ml (s/ml) and the average concentration of airborne asbestos > or = 5microm long was 0.00012fibers/ml (f/ml). For all samples, 99.9% of the samples were <0.01 f/ml for fibers longer than 5microm; no building averaged above 0.004f/ml for fibers longer than 5microm. No asbestos was detected in 27% of the buildings and in 90% of the buildings no asbestos was detected that would have been seen optically (> or = 5microm long and > or = 0.25microm wide). Background outdoor concentrations have been reported at 0.0003f/ml > or = 5microm. These results indicate that in-place ACM does not result in elevated airborne asbestos in building atmospheres approaching regulatory levels and that it does not result in a significantly increased risk to building occupants.

  4. Application of Geophysical Techniques in Glaciology

    NASA Astrophysics Data System (ADS)

    Murray, T.

    2006-05-01

    Glaciologists are faced with the problem that most processes that control ice motion or the transport of water and sediment occur either deep within the glacier ice or at the interface between it and the underlying substrate. However, glaciers are an ideal environment for the application of many geophysical techniques and they have led to significant advances in our understanding of glaciers and ice sheets. Surface and airborne radar has a long pedigree in glaciology and has been used extensively to map beds of the major ice sheets and isochrones within the ice. Cold ice, such as that in Antarctica is easy for radar energy to penetrate, but the water in warm ice scatters radar energy. For this reason it has proved more difficult to image the beds of outlet glaciers in Greenland. Recent advances, particularly in ground-penetrating radar, have meant that it has been possible to image sediment structures within the ice and to use the reflectivity at the bed capture some aspects of the basal water system. Radar energy does not normally penetrate into the beds of ice masses - which are often wet sediments. However, reflection seismics allows us to image further into the basal environment. Using the impedance contrast across the basal interface it is possible to determine whether basal sediments are frozen or unfrozen, and whether they are actively deforming or the ice is sliding over the bed. These questions are key in understanding the dynamics of an ice mass. As a glacier moves overs its bed, seismic energy can be released that provides information on the nature of the basal environment. These events record different source types and relative friction between regions of the bed (so-called "sticky" and "slippery" spots). Considerable work is required to fully exploit the potential of this technique which requires integration with GPS measurements, locating events, and modeling of source types. Geophysical techniques are an ideal tool for exploring the inaccessible

  5. STORM: A New Airborne Polarimetric Real-Aperture Radar for Earth Observations

    NASA Astrophysics Data System (ADS)

    Podvin, D. Hauser. T.; Dechambre, M.; Valentin, R.; Caudal, G.; Daloze, J.-F.

    2003-04-01

    The successful launch of the Envisat in March 2002 offers new possibilities for estimating geophysical quantities characterizing continental or sea surface using the multi-polarization ASAR. In addition, in the context of the preparation of future missions which will embark polarimetric SAR (e.g. RADARSAT2) it is important to better assess the benefit of multi-polarization or polarimetric SAR systems. Airborne radar systems remain a very useful way to validate satellite measurements and to develop or validate algorithms needed to retrieve geophysical quantities from the radar measurements. CETP has designed and developed a new airborne radar called STORM] , which has a full polarimetric capability. STORM is derived from two previous versions of airborne radars developed at CETP, namely RESSAC (Hauser et al, JGR 1992) and RENE (Leloch-Duplex et al, Annales of Telecommunications, 1996). STORM is a real-aperture, C-Band system with a FM/CW transmission and with a rotating antenna to explore in azimuth. It offers a polarization diversity, receiving the complex signal in amplitude and phase simultaneously in H and V polarizations, which makes it possible to analyze the radar cross-section in HH, VV, HV, and other cross-polarized terms related to the scattering matrix. The antenna are pointed towards the surface with a mean incidence angle of 20° and a 3-dB aperture of about 30° in elevation and 8° in azimuth. The backscattered signal is analyzed from nadir to about 35° along the look-direction in 1012 range gates every 1.53m. The first tests with this system have been carried out in October 2001 over corner reflectors , over grass and ocean. In this workshop, we will present a validation of this system based on the results obtained with this first data set. In particular, we will present the calibration method of the complex signal (amplitude, phase), and distribution of phase differences (HH/VV, HV/VH) obtained over the different scatters (corner reflectors, grass

  6. Geophysical Characterization and Monitoring for Anomalous Transport (Invited)

    NASA Astrophysics Data System (ADS)

    Day-Lewis, F. D.; Singha, K.

    2013-12-01

    For several decades, geophysical methods (e.g., electrical, electromagnetic, and radar) have been used to monitor transport of ionic tracers and contaminants, thus providing information about the spatial and temporal morphology and evolution of tracer or contaminant plumes. In the last five years, time-lapse geophysical methods have been applied to understand non-equilibrium between mobile and immobile (or less mobile) domains in porous media (e.g., fractures and matrix) and surface water (i.e., transient storage). Electrical methods have been used in combination with conventional sampling to investigate the exchange of solute between domains and thereby infer exchange rates and relative volumes of mobile and immobile domains. Other methods, including nuclear magnetic resonance and complex resistivity, have been used to study the distribution of pore sizes present, which in turn control anomalous transport. Here, we (1) review the underlying petrophysical/hydrologic link between anomalous transport and geophysical monitoring; (2) review the emerging body of work using geophysical methods to understand anomalous transport and summarize case studies involving field experiments at an aquifer-storage recovery site in Charleston, SC, and two Department of Energy sites in Hanford, WA and Naturita, CO; and (3) discuss potential future directions for geophysical research to further elucidate anomalous transport behavior.

  7. Geophysics applications in critical zone science: emerging topics.

    NASA Astrophysics Data System (ADS)

    Pachepsky, Y. A.; Martinez, G.; Guber, A.; Walthall, C. L.; Vereecken, H.

    2012-12-01

    and ecological variables are bound to vary with support and spacing. The mismatch between supports of soil measurement and geophysical footprints has been acknowledged but not resolved. Search is under way for metrics to compress dense geophysical data to be analyzed jointly with the sparser ecological information in space and time. Segmentation methods are needed that are specific to the data generated in critical zone geophysics. The geophysical data presentation will remain an art to some extent, and therefore interaction between form and content in this presentation is of interest. Currently modeling abandons the role of consumer of the structural information about the flow and transport domain, and becomes an organic part of the retrieval process. Much more is done in aquifer modeling than in modeling of variably saturated domains. Model abstraction and multimodeling can provide the functional evaluation of the retrieval components, such as segmentation, and results. The gap remains between the rich information content of the geophysical data and complexity of models in which the retrieval results are used. Field critical zone research is hardly possible without the input from geophysics. It is critical to achieve a tighter coupling of geophysical tools with other tools used in diagnostics, monitoring, and prediction of critical zone processes.

  8. Geophysical Detection of Groundwater.

    DTIC Science & Technology

    1982-04-01

    was also given to deriving a method that would be both innovative and would directly detect groundwater. Currently, there is no " black box" that uses...either the refraction method or the resistivity method to deter- mine the depth to this interface. Unless a " black box" is developed in the near...and software to be developed for groundwater exploration. Unless a " black box" is developed in the near future, the best hope for locating groundwater

  9. Photoreactivation in Airborne Mycobacterium parafortuitum

    PubMed Central

    Peccia, Jordan; Hernandez, Mark

    2001-01-01

    Photoreactivation was observed in airborne Mycobacterium parafortuitum exposed concurrently to UV radiation (254 nm) and visible light. Photoreactivation rates of airborne cells increased with increasing relative humidity (RH) and decreased with increasing UV dose. Under a constant UV dose with visible light absent, the UV inactivation rate of airborne M. parafortuitum cells decreased by a factor of 4 as RH increased from 40 to 95%; however, under identical conditions with visible light present, the UV inactivation rate of airborne cells decreased only by a factor of 2. When irradiated in the absence of visible light, cellular cyclobutane thymine dimer content of UV-irradiated airborne M. parafortuitum and Serratia marcescens increased in response to RH increases. Results suggest that, unlike in waterborne bacteria, cyclobutane thymine dimers are not the most significant form of UV-induced DNA damage incurred by airborne bacteria and that the distribution of DNA photoproducts incorporated into UV-irradiated airborne cells is a function of RH. PMID:11526027

  10. Study on analysis from sources of error for Airborne LIDAR

    NASA Astrophysics Data System (ADS)

    Ren, H. C.; Yan, Q.; Liu, Z. J.; Zuo, Z. Q.; Xu, Q. Q.; Li, F. F.; Song, C.

    2016-11-01

    With the advancement of Aerial Photogrammetry, it appears that to obtain geo-spatial information of high spatial and temporal resolution provides a new technical means for Airborne LIDAR measurement techniques, with unique advantages and broad application prospects. Airborne LIDAR is increasingly becoming a new kind of space for earth observation technology, which is mounted by launching platform for aviation, accepting laser pulses to get high-precision, high-density three-dimensional coordinate point cloud data and intensity information. In this paper, we briefly demonstrates Airborne laser radar systems, and that some errors about Airborne LIDAR data sources are analyzed in detail, so the corresponding methods is put forwarded to avoid or eliminate it. Taking into account the practical application of engineering, some recommendations were developed for these designs, which has crucial theoretical and practical significance in Airborne LIDAR data processing fields.

  11. Data Analysis of Airborne Electromagnetic Bathymetry.

    DTIC Science & Technology

    1985-04-01

    ploration Method. CIMM Bulletin, May, pp. 1-12. terpretation of Airborne Electromagnetic Data. Turnross, J., H. F. Morrison, and A. Becker (1984...System. CIMM Bulletin, v. 66, pp. 104-109. Fraser. D. C. (1978). Resistivity Mapping with an Air- report, Office of Naval Research, Washington, DC

  12. Geophex Airborne Unmanned Survey System (GAUSS). Topical report, October 1993--March 1995

    SciTech Connect

    1995-03-01

    The objectives of the project are to construct a geophysical sensor system based on a remotely operated model helicopter (ROH) and to evaluate the efficacy of the system for characterization of hazardous environmental sites. Geophex Airborne Unmanned Survey System (GAUSS) is a geophysical survey system that uses a ROH as the survey vehicle. We have selected the ROH because of its advantages over fixed wing and ground based vehicles. Lower air speed and superior maneuverability of the ROH make it better suited for geophysical surveys than a fixed wing model aircraft. The ROH can fly close to the ground, allowing detection of weak or subtle anomalies. Unlike ground based vehicles, the ROH can traverse difficult terrain while providing a stable sensor platform. ROH does not touch the ground during the course of a survey and is capable of functioning over water and surf zones. The ROH has been successfully used in the motion picture industry and by geology companies for payload bearing applications. The only constraint to use of the airborne system is that the ROH must remain visible to the pilot. Obstructed areas within a site can be characterized by relocating the base station to alternate positions. GAUSS consists of a ROH with radio controller, a data acquisition and processing (DAP) system, and lightweight digital sensor systems. The objective of our Phase I research was to develop a DAP and sensors suitable for ROH operation. We have constructed these subsystems and integrated them to produce an automated, hand-held geophysical surveying system, referred to as the ``pre-prototype``. We have performed test surveys with the pre-prototype to determine the functionality of the and DAP and sensor subsystems and their suitability for airborne application. The objective of the Phase II effort will be to modify the existing subsystems and integrate them into an airborne prototype. Efficacy of the prototype for geophysical survey of hazardous sites will then be determined.

  13. Field Geophysics at SAGE: Strategies for Effective Education

    NASA Astrophysics Data System (ADS)

    Braile, L. W.; Baldridge, W. S.; Jiracek, G. R.; Biehler, S.; Ferguson, J. F.; Pellerin, L.; McPhee, D. K.; Bedrosian, P. A.; Snelson, C. M.; Hasterok, D. P.

    2011-12-01

    SAGE (Summer of Applied Geophysical Experience) is a unique program of education and research in geophysical field methods for undergraduate and graduate students from any university and for professionals. The core program is held for 4 weeks each summer in New Mexico and for an additional week in the following academic year in San Diego for U.S. undergraduates supported by the NSF Research Experience for Undergraduates (REU) program. Since SAGE was initiated in 1983, 730 students have participated in the program. NSF REU funding for SAGE began in 1990 and 319 REU students have completed SAGE through 2011. The primary objectives of SAGE are to teach the major geophysical exploration methods (seismic, gravity, magnetics, electromagnetics); apply these methods to the solution of specific problems (environmental, archaeological, hydrologic, geologic structure and stratigraphy); gain experience in processing, modeling and interpretation of geophysical data; and integrate the geophysical models and interpretations with geology. Additional objectives of SAGE include conducting research on the Rio Grande rift of northern New Mexico, and providing information on geophysics careers and professional development experiences to SAGE participants. Successful education, field and research strategies that we have implemented over the years include: 1. learn by doing; 2. mix lecture/discussion, field work, data processing and analysis, modeling and interpretation, and presentation of results; 3. a two-tier team approach - method/technique oriented teams and interpretation/integration teams (where each team includes persons representing different methods), provides focus, in-depth study, opportunity for innovation, and promotes teamwork and a multi-disciplinary approach; 4. emphasis on presentations/reports - each team (and all team members) make presentation, each student completes a written report; 5. experiment design discussion - students help design field program and consider

  14. Geophysical applications of satellite altimetry

    SciTech Connect

    Sandwell, D.T. )

    1991-01-01

    Publications related to geophysical applications of Seasat and Geosat altimetry are reviewed for the period 1987-1990. Problems discussed include geoid and gravity errors, regional geoid heights and gravity anomalies, local gravity field/flexure, plate tectonics, and gridded geoid heights/gravity anomalies. 99 refs.

  15. BROADBAND DIGITAL GEOPHYSICAL TELEMETRY SYSTEM.

    USGS Publications Warehouse

    Seeley, Robert L.; Daniels, Jeffrey J.

    1984-01-01

    A system has been developed to simultaneously sample and transmit digital data from five remote geophysical data receiver stations to a control station that processes, displays, and stores the data. A microprocessor in each remote station receives commands from the control station over a single telemetry channel.

  16. Temperature Dependence of Thermal Expansion for Geophysical Minerals

    NASA Astrophysics Data System (ADS)

    Fang, Zheng-Hua

    2015-07-01

    A simple and straightforward method for evaluating and predicting the volume and volumetric thermal expansivity for geophysical minerals at high temperatures is developed in this paper based on the approximations that the product of the thermal expansion coefficient and the isothermal bulk modulus as well as the isothermal bulk modulus are both linearly dependent with temperature. The tests on four geophysica