Magnitude versus offset (MVO)

The variation in the magnitude of the frequency domain of the controlled-source electromagnetic field for any one receiver with the distance from the source as it is towed towards and then away from the receiver.

The magnitude of the electromagnetic response can also be mapped for a grid of receivers for a fixed offset. MVO measurements are usually normalised using results from a reference receiver.

MVO is an attribute derived from the electromagnetic measurements. It is the first data analysis performed and used for quality control, and may sometimes give an early indication of whether a significant normalised anomalous amplitude response has been measured. Although the approach does not provide reliable depth information, it has a short turnaround time and enables a qualitative assessment to be made that shows the relative changes in resistivity, which can help to verify the accuracy of the initial resistivity model.