The Use of Multi-Level Potential Field Data in Regional, Geophysical Modelling
Jörg Ebbing1, Reynir F. Reynisson2, and Jan Reidar Skilbrei1
1Geological Survey of Norway, Trondheim, Norway
2Petroleum Engineering and Applied Geophysics, NTNU, Trondheim, Norway
Modeling of potential field data suffers from the ambiguity problem and constraining data are needed to minimize the uncertainty of forward and inverse models. Useful information which can limit the uncertainties is contained in the frequency content of the potential field data. Routinely, wavelength filtering and methods like power-spectrum estimates have been used in the past in interpretation of potential field data. However, shallow geological structures often are not limited to a certain wavelength and overlap in their characteristic wavelength with deeper-seated anomalies (e.g. cratonic basins).
The availability of data sets at different levels, e.g. ground data, ship borne data, airborne data and satellite data, allows nowadays modeling simultaneously potential fields from different heights, and overcomes therewith the necessity of wavelength-filtering. Models can be tested immediately against their response in multi-level data-sets, which increases the uncertainty of the solutions. Especially, in inversion of potential field data the use of different observation levels minimizes the uncertainty in the analysis of sources superposed from different depth. We present key examples of multi-level modeling of the magnetic field and gravity field for the Oslo Graben, Barents Sea and mid-Norwegian margin, where multi-level data sets have been used to model crustal intrusives and crustal structure underlying sedimentary basins.
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