TY  - JOUR
A1  - Klose, Tim
A1  - Guillemoteau, Julien
A1  - Vignoli, Giulio
A1  - Walter, Judith
A1  - Herrmann, Andreas
A1  - Tronicke, Jens
T1  - Structurally constrained inversion by means of a Minimum Gradient Support regularizer
BT  - examples of FD-EMI data inversion constrained by GPR reflection data
JF  - Geophysical journal international
N2  - Many geophysical inverse problems are known to be ill-posed and, thus, requiring some kind of regularization in order to provide a unique and stable solution. A possible approach to overcome the inversion ill-posedness consists in constraining the position of the model interfaces. For a grid-based parameterization, such a structurally constrained inversion can be implemented by adopting the usual smooth regularization scheme in which the local weight of the regularization is reduced where an interface is expected. By doing so, sharp contrasts are promoted at interface locations while standard smoothness constraints keep affecting the other regions of the model. In this work, we present a structurally constrained approach and test it on the inversion of frequency-domain electromagnetic induction (FD-EMI) data using a regularization approach based on the Minimum Gradient Support stabilizer, which is capable to promote sharp transitions everywhere in the model, i.e., also in areas where no structural a prioriinformation is available. Using 1D and 2D synthetic data examples, we compare the proposed approach to a structurally constrained smooth inversion as well as to more standard (i.e., not structurally constrained) smooth and sharp inversions. Our results demonstrate that the proposed approach helps in finding a better and more reliable reconstruction of the subsurface electrical conductivity distribution, including its structural characteristics. Furthermore, we demonstrate that it allows to promote sharp parameter variations in areas where no structural information are available. Lastly, we apply our structurally constrained scheme to FD-EMI field data collected at a field site in Eastern Germany to image the thickness of peat deposits along two selected profiles. In this field example, we use collocated constant offset ground-penetrating radar (GPR) data to derive structural a priori information to constrain the inversion of the FD-EMI data. The results of this case study demonstrate the effectiveness and flexibility of the proposed approach.
KW  - Controlled source electromagnetics (CSEM)
KW  - Inverse theory
KW  - Electrical properties
KW  - Ground penetrating radar
KW  - Frequency Domain Electromagnetics
KW  - Inversion
Y1  - 2023
U6  - https://doi.org/10.1093/gji/ggad041
SN  - 0956-540X
SN  - 1365-246X
VL  - 233
IS  - 3
SP  - 1938
EP  - 1949
PB  - Oxford Univ. Press
CY  - Oxford
ER  -