INTERPRETATION OF MULTIPLE RESIDUAL GRAVITY ANOMALIES BY SPHERICAL BODIES

The present study developed an inversion scheme for the interpretation of multiple residual gravity
anomalies measured along a profile by spherical bodies. It is based on the regularized conjugate gradient method. The
scheme simultaneously inverts for the characteristic parameters (depths z’s and the amplitude coefficients A’s) of all
approximative bodies in the logarithmic space of model parameters (log(z) and log(|A|)) rather than in the space of
model parameters themselves (z and A). Carrying out the inversion in the logarithmic space of model parameters has a
number of important benefits. First, it makes the logarithmic parameters and their corresponding sensitivities (terms of
the Jacobian matrix) comparable and balanced. Second, it makes the sensitivity terms dimensionally the same. Third, it
imposes the positive property of the model parameters, which essentially maintains the convergence and stability of the
scheme. The developed scheme has been successfully verified on synthetic examples without noise; it recovered the true
values of all inverse parameters of the underlying bodies. Furthermore, the scheme is stable and can estimate the
inverse parameters of the buried target with acceptable accuracy when applied to data contaminated with noise. The
validity of the scheme for practical applications has been illustrated on a field example from Cuba for chromite
prospecting. The scheme can be applicable for mineral exploration and shallow and deep earth imaging. It can produce
non-unique solution and is sensitive to the initial guess choice.