Conductivity depth transforms are a useful tool for quickly creating a subsurface image from airborne electromagnetic data. Time-domain EM (TEM) transforms have utilized the response from a step-off waveform and a thin sheet or homogenous halfspace model to determine exploration depth. The induced current system from a step-off waveform has been studied in the literature. However, the current system from other waveforms, and in particular the current system during the on-time, has not been addressed. Here, we calculate the induced current for a halfsine waveform during the off-time and the on-time. We show that the on-time current density is concentrated near surface compared to the off-time. Using field data, we then compute the halfspace apparent resistivity for an on-time channel and the first off-time channel as well as five frequencies from a frequency domain survey; the on-time apparent resistivity correlates well with the high-frequency apparent resistivity while the first off-time channel correlates with a mid-frequency apparent resistivity.


Article metrics loading...

Loading full text...

Full text loading...


Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error