15  Summary

What were the most important insights?

• Understanding of Maxwell’s equations
• Derivation of the curl-curl equation of electromagnetics
• Dipole sources
• Incremental modifications of the underlying model: From uniform full-space to layered half-space
• Understanding time-domain induction
• Implementation of Hankel integrals
• Excurse to 2D and 3D modelling applications

Why is the lecture on the Theory of EM important?

• All EM geophysics - from magnetotellurics (MT) to controlled-source EM (CSEM) - relies on solving Maxwell’s equations under specific boundary conditions

• Knowing how fields decay, diffuse, or reflect allows for optimal sensor placement, source design, and noise mitigation

• Understanding the theory is essential for developing accurate forward solvers and stable, regularized inverse algorithms

• Time-domain EM, airborne EM, and marine EM all evolved from theoretical insights