Question

What is/are the primary effect(s) of applying upward continuation to magnetic field data?

• A. Decrease in the relative influence of shallow magnetic sources
• B. Increase in the relative influence of deeper magnetic sources
• C. Improvement in the detection of near-surface magnetic sources
• D. Movement of shallow magnetic sources closer to the observation plane

Hint:

Upward continuation smoothens magnetic data by attenuating shallow source effects and highlighting deeper structures — useful in regional studies.

Answer 1

The Correct Option is A, B

Step 1: Understanding upward continuation. 
Upward continuation is a mathematical transformation applied to potential field data (e.g., magnetic or gravity data) to simulate measurements at a higher elevation than the actual observation level. 
Step 2: Effects on magnetic sources. It reduces the influence of shallow magnetic sources because their field strength decays rapidly with height. 
In contrast, it relatively enhances the contribution from deeper sources, as their field strength decays more slowly.
Step 3: Eliminating incorrect options.
(C) is incorrect because upward continuation suppresses, rather than enhances, near-surface anomalies. 
(D) is incorrect; it’s a misinterpretation — sources do not move, only their apparent influence changes.