Karl J Ellefsen
Karl Ellefsen is an Emeritus with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 64
Monitoring soil geochemistry in the urban environment: A comparison of studies in 1972 and 2005 in Denver, Colorado
No abstract available
Authors
David B. Smith, Karl J. Ellefsen, Ronald G. Garrett, L. Graham Closs
Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: a potential source of geogenic Cr(VI) to groundwater
Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization’s maximum contaminant level for drinking water (50 μg L−1) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacram
Authors
Christopher T. Mills, Jean Morrison, Martin B. Goldhaber, Karl J. Ellefsen
Geochemical data for Colorado soils: Results from the 2006 state-scale geochemical survey
In 2006, soil samples were collected at 960 sites (1 site per 280 square kilometers) throughout the state of Colorado. These samples were collected from a depth of 0-15 centimeters and, following a near-total multi-acid digestion, were analyzed for a suite of more than 40 major and trace elements. The resulting data set provides a baseline for the natural variation in soil geochemistry for Colorad
Authors
David B. Smith, Karl J. Ellefsen, James E. Kilburn
Soil Geochemical Data for the Wyoming Landscape Conservation Initiative Study Area
In 2008, soil samples were collected at 139 sites throughout the Wyoming Landscape Conservation Initiative study area in southwest Wyoming. These samples, representing a density of 1 site per 440 square kilometers, were collected from a depth of 0-5 cm and analyzed for a suite of more than 40 major and trace elements following a near-total multi-acid extraction. In addition, soil pH, electrical co
Authors
David B. Smith, Karl J. Ellefsen
High-Frequency, Crosswell Radar Data Collected in a Laboratory Tank
Crosswell radar data were collected among three wells in a laboratory tank filled with dry sand. Embedded within the sand was a long plastic box, which was the target for the data collection. Two datasets were collected between each pair of wells, making a total of six datasets. The frequencies in the data ranged from 0.5 to 1.5 gigahertz, and the peak frequency was 0.9 gigahertz. The data are wel
Authors
Bas Peters, Craig W. Moulton, Karl J. Ellefsen, Robert Horton, Jason R. McKenna
Frequency domain, waveform inversion of laboratory crosswell radar data
A new waveform inversion for crosswell radar is formulated in the frequency-domain for a 2.5D model. The inversion simulates radar waves using the vector Helmholtz equation for electromagnetic waves. The objective function is minimized using a backpropagation method suitable for a 2.5D model. The inversion is tested by processing crosswell radar data collected in a laboratory tank. The estimated m
Authors
Karl J. Ellefsen, Aldo T. Mazzella, Robert Horton, Jason R. McKenna
A comparison of phase inversion and traveltime tomography for processing near-surface refraction traveltimes
With phase inversion, one can estimate subsurface velocities using the phases of first-arriving waves, which are the frequency-domain equivalents of the traveltimes. Phase inversion is modified to make it suitable for processing traveltimes from near-surface refraction surveys. The modifications include parameterizing the model, correcting the observed phases, and selecting the complex frequency.
Authors
Karl J. Ellefsen
Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media
Green's functions for radar waves propagating in heterogeneous 2.5D media might be calculated in the frequency domain using a hybrid method. The model is defined in the Cartesian coordinate system, and its electromagnetic properties might vary in the x- and z-directions, but not in the y-direction. Wave propagation in the x- and z-directions is simulated with the finite-difference method, and wave
Authors
K.J. Ellefsen, D. Croize, A.T. Mazzella, J.R. McKenna
Field Demonstrations of Five Geophysical Methods that Could Be Used to Characterize Deposits of Alluvial Aggregate
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 refra
Authors
K.J. Ellefsen, B.L. Burton, J.E. Lucius, S.S. Haines, D.V. Fitterman, J.A. Witty, D. Carlson, B. Milburn, W. H. Langer
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits
This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and th
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits
This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and th
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
S-wave refraction survey of alluvial aggregate
An S-wave refraction survey was conducted in the Yampa River valley near Steamboat Springs, Colo., to determine how well this method could map alluvium, a major source of construction aggregate. At the field site, about 1 m of soil overlaid 8 m of alluvium that, in turn, overlaid sedimentary bedrock. The traveltimes of the direct and refracted S-waves were used to construct velocity cross sections
Authors
Karl J. Ellefsen, Gary J. Tuttle, Jackie M. Williams, Jeffrey E. Lucius
Science and Products
Filter Total Items: 64
Monitoring soil geochemistry in the urban environment: A comparison of studies in 1972 and 2005 in Denver, Colorado
No abstract available
Authors
David B. Smith, Karl J. Ellefsen, Ronald G. Garrett, L. Graham Closs
Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: a potential source of geogenic Cr(VI) to groundwater
Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization’s maximum contaminant level for drinking water (50 μg L−1) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacram
Authors
Christopher T. Mills, Jean Morrison, Martin B. Goldhaber, Karl J. Ellefsen
Geochemical data for Colorado soils: Results from the 2006 state-scale geochemical survey
In 2006, soil samples were collected at 960 sites (1 site per 280 square kilometers) throughout the state of Colorado. These samples were collected from a depth of 0-15 centimeters and, following a near-total multi-acid digestion, were analyzed for a suite of more than 40 major and trace elements. The resulting data set provides a baseline for the natural variation in soil geochemistry for Colorad
Authors
David B. Smith, Karl J. Ellefsen, James E. Kilburn
Soil Geochemical Data for the Wyoming Landscape Conservation Initiative Study Area
In 2008, soil samples were collected at 139 sites throughout the Wyoming Landscape Conservation Initiative study area in southwest Wyoming. These samples, representing a density of 1 site per 440 square kilometers, were collected from a depth of 0-5 cm and analyzed for a suite of more than 40 major and trace elements following a near-total multi-acid extraction. In addition, soil pH, electrical co
Authors
David B. Smith, Karl J. Ellefsen
High-Frequency, Crosswell Radar Data Collected in a Laboratory Tank
Crosswell radar data were collected among three wells in a laboratory tank filled with dry sand. Embedded within the sand was a long plastic box, which was the target for the data collection. Two datasets were collected between each pair of wells, making a total of six datasets. The frequencies in the data ranged from 0.5 to 1.5 gigahertz, and the peak frequency was 0.9 gigahertz. The data are wel
Authors
Bas Peters, Craig W. Moulton, Karl J. Ellefsen, Robert Horton, Jason R. McKenna
Frequency domain, waveform inversion of laboratory crosswell radar data
A new waveform inversion for crosswell radar is formulated in the frequency-domain for a 2.5D model. The inversion simulates radar waves using the vector Helmholtz equation for electromagnetic waves. The objective function is minimized using a backpropagation method suitable for a 2.5D model. The inversion is tested by processing crosswell radar data collected in a laboratory tank. The estimated m
Authors
Karl J. Ellefsen, Aldo T. Mazzella, Robert Horton, Jason R. McKenna
A comparison of phase inversion and traveltime tomography for processing near-surface refraction traveltimes
With phase inversion, one can estimate subsurface velocities using the phases of first-arriving waves, which are the frequency-domain equivalents of the traveltimes. Phase inversion is modified to make it suitable for processing traveltimes from near-surface refraction surveys. The modifications include parameterizing the model, correcting the observed phases, and selecting the complex frequency.
Authors
Karl J. Ellefsen
Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media
Green's functions for radar waves propagating in heterogeneous 2.5D media might be calculated in the frequency domain using a hybrid method. The model is defined in the Cartesian coordinate system, and its electromagnetic properties might vary in the x- and z-directions, but not in the y-direction. Wave propagation in the x- and z-directions is simulated with the finite-difference method, and wave
Authors
K.J. Ellefsen, D. Croize, A.T. Mazzella, J.R. McKenna
Field Demonstrations of Five Geophysical Methods that Could Be Used to Characterize Deposits of Alluvial Aggregate
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 refra
Authors
K.J. Ellefsen, B.L. Burton, J.E. Lucius, S.S. Haines, D.V. Fitterman, J.A. Witty, D. Carlson, B. Milburn, W. H. Langer
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits
This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and th
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits
This report is an introduction to surface geophysical techniques that aggregate producers can use to characterize known deposits of sand and gravel. Five well-established and well-tested geophysical methods are presented: seismic refraction and reflection, resistivity, ground penetrating radar, time-domain electromagnetism, and frequency-domain electromagnetism. Depending on site conditions and th
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
S-wave refraction survey of alluvial aggregate
An S-wave refraction survey was conducted in the Yampa River valley near Steamboat Springs, Colo., to determine how well this method could map alluvium, a major source of construction aggregate. At the field site, about 1 m of soil overlaid 8 m of alluvium that, in turn, overlaid sedimentary bedrock. The traveltimes of the direct and refracted S-waves were used to construct velocity cross sections
Authors
Karl J. Ellefsen, Gary J. Tuttle, Jackie M. Williams, Jeffrey E. Lucius