Space Domain Iterative Inversion and its Application to the Western Anatolian Grabens

Abstract

Anomalous density distribution of the subsurface is obtained using iterative techniques involving the minimization of volume and concentration around the center of gravity criteria. Also an attempt is here made to define the vertical geometry of bodies causing magnetic anomalies by iterative approach using the criteria of minimization of volume.

To linearize the problem in the space domain the subsurface strata is divided into rectangular blocks. Therefore, only the densities and magnetic values of the blocks are considered. Noise is also included into formulation and the least squares approach of solution can be used with the noise-density weighting functions incorporated.

The practical effectiveness of the method was tested for using theoritical models with very satisfactory result for both gravity and magnetic fields inversion.

The method was applied to observed gravity data over the Western Anatolia graben. The approache was used to get unconstrained and constrained density distributions for the grabens in this region. It was found that the minimization of volume approach was concentrating the density distribution to the uppermost blocks. This problem was however overcome in the center of gravity approach.

The advantage of the approaches is that desirable geological characteristics are automatically incorporated into the model with a minimum of subjective judgements on the part of the interpreter. Resolution matrix can be easily used to determine the contributions of block densities to the solution.