Assessment of the TEM‐8 Airborne Electromagnetic System for Ground Conductivity Measurements

Development And Evaluation Of A Second-Generation Airborne Electromagnetic System For Detection Of Unexploded Ordnance

10.3997/2214-4609-pdb.191.11uxo8 ◽

2002 ◽

Author(s):

William E. Doll ◽

T. Jeffrey Gamey ◽

Les P. Beard ◽

David T. Bell ◽

J.S. Holladay ◽

...

Keyword(s):

Second Generation ◽

Unexploded Ordnance ◽

Electromagnetic System ◽

Airborne Electromagnetic

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An example of 3D conductivity mapping using the TEMPEST airborne electromagnetic system

Exploration Geophysics ◽

10.1071/eg00162 ◽

2000 ◽

Vol 31 (1-2) ◽

pp. 162-172 ◽

Cited By ~ 60

Author(s):

Richard Lane ◽

Andy Green ◽

Chris Golding ◽

Matt Owers ◽

Phil Pik ◽

...

Keyword(s):

Electromagnetic System ◽

The Tempest ◽

Airborne Electromagnetic

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MAPPING EARTH CONDUCTIVITIES USING A MULTIFREQUENCY AIRBORNE ELECTROMAGNETIC SYSTEM

Geophysics ◽

10.1190/1.1440837 ◽

1978 ◽

Vol 43 (3) ◽

pp. 563-575 ◽

Cited By ~ 7

Author(s):

H. O. Seigel ◽

D. H. Pitcher

Keyword(s):

Thin Sheet ◽

Radar Altimeter ◽

Electromagnetic System ◽

Near Surface ◽

Quantitative Estimates ◽

Simple Geometry ◽

Airborne Electromagnetic ◽

Groundwater Mapping ◽

Actual Field ◽

Depth Of Burial

The Tridem vertical coplanar airborne electromagnetic system provides simultaneous in‐phase and quadrature information at frequencies of 500, 2000 and 8000 Hz. The system can map a broad range of earth conductors of simple geometry and provide quantitative estimates of their conductivities and dimensions. Computer programs have been developed to automatically interpret the six channels of Tridem data, plus the output of an accurate radar altimeter, to determine the depth of burial, conductivity and thickness of a near‐surface, flat‐lying conducting horizon. In limiting cases, the interpretation provides the conductance (conductivity‐thickness product) of a thin sheet (ranging from 100 mmhos to 100 mhos) or the conductivity of a homogeneous earth (ranging from 1 mmhos/m to 10 mhos/m). Two actual field examples are presented from Ontario, Canada; one relating to the mapping of overburden conditions (sand, clay and rock, etc) and the other to the mapping of the distribution of a buried lignite deposit. Other areas of potential application of the system to surficial materials would include groundwater mapping, permafrost investigations, and civil engineering studies for roads and pipelines.

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27. Viability of an Airborne Electromagnetic System for Mapping of Shallow Buried Metals

Near-Surface Geophysics ◽

10.1190/1.9781560801719.ch27 ◽

2005 ◽

pp. 653-662

Author(s):

William E. Doll ◽

T. Jeffrey Gamey ◽

J. Scott Holladay ◽

James L. C. Lee

Keyword(s):

Electromagnetic System ◽

Airborne Electromagnetic

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EARTH CONDUCTIVITY DETERMINATIONS EMPLOYING A SINGLE SUPERCONDUCTING COIL

Geophysics ◽

10.1190/1.2035912 ◽

1976 ◽

Vol 41 (6) ◽

pp. 1184-1206 ◽

Cited By ~ 8

Author(s):

H. F. Morrison ◽

William Dolan ◽

Abhijit Dey

Keyword(s):

Large Scale ◽

Low Frequency ◽

High Sensitivity ◽

Input Resistance ◽

Measurement Sensitivity ◽

Superconducting Wires ◽

Superconducting Coil ◽

Airborne Electromagnetic ◽

Earth Conductivity ◽

Ground Conductivity

A low‐frequency airborne electromagnetic prospecting method has been developed which exploits the inherent low resistance of a superconducting coil. Changes in the input resistance of this coil are monitored in the presence of the conducting earth. The response of the system, the change in the input resistance, is proportional to the quadrature secondary magnetic field at the transmitter, although unlike two‐coil systems, the response does not decrease with increasing frequency. This research has demonstrated that superconducting wires, large scale nonmetallic cryostats, the requisite measurement circuitry, and an appropriate data acquisition system are realizable in a practical flight configuration. The unicoil presents the following significant advantages in electromagnetic prospecting: 1) The measurement sensitivity is not limited by the relative coil motion experienced by two‐coil systems. 2) Ample field strength may be supplied to override ambient noise. 3) Optimum frequencies for specific geologic sections are easily implemented in the range of 10 to 2000 Hz. 4) Maps of ground conductivity may be obtained because precise thermal stability is maintained and the measurement, therefore, is absolute. 5) The point source observation minimizes analytic complexity. 6) The combination of the foregoing features with multiple frequency operation, yields a system of potentially high sensitivity and unprecedented depth of exploration. The unicoil system also possesses some disadvantages: 1) An operational complexity results from the cryogenic procedures required in the field, and 2) the heavy sensor requires a large helicopter.

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COMPUTER DATA PROCESSING AND QUANTITATIVE INTERPRETATION OF AIRBORNE RESISTIVITY SURVEYS

Geophysics ◽

10.1190/1.1440570 ◽

1975 ◽

Vol 40 (5) ◽

pp. 818-830 ◽

Cited By ~ 9

Author(s):

G. J. Palacky ◽

F. L. Jagodits

Keyword(s):

Electric Fields ◽

Simultaneous Recording ◽

Quantitative Interpretation ◽

Geologic Mapping ◽

Electromagnetic System ◽

Computer Data ◽

Type Curves ◽

Intermediate Data ◽

Processing Cost ◽

Airborne Electromagnetic

The recently constructed airborne electromagnetic system called E-Phase measures the intensity of the vertical and horizontal electric fields. Standard broadcasting, VLF, and LF navigation aid transmitters are used as sources of the primary EM field. A system of this kind responds best to horizontal layers of large extent and therefore is suitable for geologic mapping and for the detection of resistive materials such as gravel and permafrost. A successful application of the system would not have been possible without digital recording of the data and subsequent computer processing. An efficient algorithm consisting of three processing steps assures low processing cost and provides for two intermediate data checks. Final outputs are printer plots of apparent resistivity for all flight lines and maps of stacked profiles or contours. Quantitative interpretation was made possible by the simultaneous recording of the data at three transmitter frequencies and by the availability of theoretical solutions for layered media. Instead of generating an atlas of type curves, an interactive program was written which enables the geophysicist to rapidly obtain apparent resistivities assuming a three‐layer model. A close match with the measured data is easy to achieve when a reasonable estimate of two of the parameters (resistivities, thicknesses) can be made initially. The interpretation procedure is demonstrated on a case history, a 1973 survey conducted near Wadena, Saskatchewan.

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Inversion of ground constant offset loop-loop electromagnetic data for a large range of induction numbers

Geophysics ◽

10.1190/geo2014-0005.1 ◽

2015 ◽

Vol 80 (1) ◽

pp. E11-E21 ◽

Cited By ~ 18

Author(s):

Julien Guillemoteau ◽

Pascal Sailhac ◽

Charles Boulanger ◽

Jérémie Trules

Keyword(s):

Synthetic Data ◽

Test Site ◽

Maxwell Theory ◽

Data Set ◽

Electromagnetic Data ◽

Apparent Conductivity ◽

Airborne Electromagnetic ◽

Phase Data ◽

Ground Conductivity ◽

Good Agreement

Ground loop-loop electromagnetic surveys are often conducted to fulfill the low-induction-number condition. To image the distribution of electric conductivity inside the ground, it is then necessary to collect a multioffset data set. We considered that less time-consuming constant offset measurements can also reach this objective. This can be achieved by performing multifrequency soundings, which are commonly performed for the airborne electromagnetic method. Ground multifrequency soundings have to be interpreted carefully because they contain high-induction-number data. These data are interpreted in two steps. First, the in-phase and out-of-phase data are converted into robust apparent conductivities valid for all the induction numbers. Second, the apparent conductivity data are inverted in 1D and 2D to obtain the true distribution of the ground conductivity. For the inversion, we used a general half-space Jacobian for the apparent conductivity valid for all the induction numbers. This method was applied and validated on synthetic data computed with the full Maxwell theory. The method was then applied on field data acquired in the test site of Provins, in the Parisian basin, France. The result revealed good agreement with borehole and geologic information, demonstrating the applicability of our method.

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