REGCONT: A Matlab based program for stable downward continuation of geophysical potential fields using Tikhonov regularization

Downward continuation of potential fields is a powerful, but very unstable tool used in the processing and interpretation of geophysical data sets. Treatment of the instability problem has been realized by various authors in different ways. The Tikhonov regularization approach is one of the most robust. It is based on a low-pass filter derivation in the Fourier spectral domain, by means of a minimization problem solution. We highlight the most important characteristics from its theoretical background and present its realization in the form of a Matlab-based program. The optimum regularization parameter value is selected as a local minimum of constructed Lp-norms functions—in the majority of cases, the C-norms give the best results. We demonstrate very good stabilizing properties of this method on several synthetic models and one real-world example from high-definition magnetometry. The main output of the proposed software solution is the estimation of the depth to source below the potential field measurement level.

► We analyse the properties of stable regularized downward continuation procedure in geophysical fields transformation. ► For the estimation of optimum regularization parameter we use mainly C-norm functions. ► This approach is relatively independent of the sampling interval. ► Main interpretation value is the depth-estimation of first important shallow sources.