Time Domain Electromagnetic Measurements to Determine Water Quality in the Floridan Aquifer

1992 ◽  
Author(s):  
Pieter Hoekstra ◽  
Jim Hild ◽  
David Toth
Keyword(s):  
Water Quality ◽  
Time Domain ◽  
Floridan Aquifer ◽  
Electromagnetic Measurements ◽  
Time Domain Electromagnetic

USE OF DECAY PATTERNS FOR THE CLASSIFICATION OF ANOMALIES IN TIME‐DOMAIN AEM MEASUREMENTS

Geophysics ◽  
1976 ◽  
Vol 41 (5) ◽  
pp. 1031-1041 ◽  
Author(s):  
G. J. Palacky
Keyword(s):  
Time Domain ◽  
Field Measurements ◽  
System Response ◽  
Electromagnetic Measurements ◽  
Time Domain Electromagnetic ◽  
Decay Pattern ◽  
Body Parameters ◽  
Flight Computer

Interpretation of time‐domain electromagnetic measurements normally comprises visual anomaly selection and determination of body parameters, such as conductance, depth, and dip. A study is made to examine the possibility of in‐flight computer interpretation on the basis of decay patterns. Analysis of system response over conducting loops, vertical and dipping sheets, horizontal strips, and a half‐space indicates that identification of models and some of their parameters by decay patterns is feasible. By the simultaneous use of vertical and horizontal coil receivers, a reliable recognition of models may be achieved. While the secondary magnetic field over a conducting loop decays exponentially, other models show distinctive nonexponential patterns. Decay patterns are affected by conductance and conductor size, but less by depth and dip variations. Field measurements indicate that decay pattern may be used to distinguish between geologic bodies of various types.

On: “Induced‐polarization effects in time‐domain electromagnetic measurements” by M. F. Flis, G. A. Newman, and G. W. Hohmann (GEOPHYSICS, 54, 514–523, April 1989).

Geophysics ◽  
1989 ◽  
Vol 54 (12) ◽  
pp. 1655-1656 ◽  
Author(s):  
Richard Smith
Keyword(s):  
Time Domain ◽  
Three Dimensional ◽  
Polarization Current ◽  
Electromagnetic Measurements ◽  
Charging Current ◽  
Time Domain Electromagnetic ◽  
Time Domain Response ◽  
The Time Domain ◽  
Theoretical Results ◽  
Insight Into

Flis et al. provide useful insight into the time‐domain response of three‐dimensional polarizable bodies; however, their inference that negative transients are caused by a polarization current which reverses direction disagrees with the previously published theoretical results of Smith et al. (1988) and Smith and West (1988), who found that the polarization current is always negative (provided that the chargeability m and charging current are positive).

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