Karl J Ellefsen
Karl Ellefsen is an Emeritus with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 65
Frequency domain, waveform inversion of laboratory crosswell radar data 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...
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 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...
Authors
Karl J. Ellefsen
Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media 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...
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 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...
Authors
K.J. Ellefsen, B.L. Burton, J.E. Lucius, S.S. Haines, D.V. Fitterman, J.A. Witty, David R. Carlson, B. Milburn, W. H. Langer
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits 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...
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits 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...
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
Science and Products
Filter Total Items: 65
Frequency domain, waveform inversion of laboratory crosswell radar data 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...
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 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...
Authors
Karl J. Ellefsen
Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media 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...
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 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...
Authors
K.J. Ellefsen, B.L. Burton, J.E. Lucius, S.S. Haines, D.V. Fitterman, J.A. Witty, David R. Carlson, B. Milburn, W. H. Langer
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits 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...
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen
An Introduction to Using Surface Geophysics to Characterize Sand and Gravel Deposits 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...
Authors
Jeffrey E. Lucius, William H. Langer, Karl J. Ellefsen