NEW APPROACHES TO INTERPRET

Abstract

In the present thesis. lour new methods for interpreting gravity data have been developed.

In tf1e .first method. a non-iterative approach to determine the depth of a buried structure from the residual gravity anomaly has been developed. The method is based on the assumption that. the sum of the gravity anomaly values due to the model is equal

t\l the sum of the (lbsen•cd residual gravity anomaly \•;dues. Formulas h;we been dcri\•ed

for a semi-infinite Yertieal c •linder. horizontal cylinder. and for a sphere. l'rocL'Liures ar.:

also formulated to estimate the physical property parameter related to the rnass. The

0 usefulness of the present method over the non-iterative least-square method

(Abdclrahman and EI-Araby. 1993) has been demonstrated by extreme examples. namely. estimating the depth and the physical pruperty parameters of an indicated wrtical cylinder model under the grossly simplification that. the gra\•ity anomal;. is caused by a horill,nt;d cylinder model 01 a sphere' model and \•icc \Tr:.::t Fin;dh•. the method is applied to a field data from Sweden.

In the second method. three different least-squares approaches to determine. successively. the depth. shape (shape factor). and amplitude coerticic111 relat<:d to the radius and density contr 1st of a buried structure l'rom the residual gra\•ity aJllHll<lh• ha\•e been dewlopnl. lly ddining the anomaly value• :!(::oa:-:) at the origin on the prulilc. tliL• problem of depth determination has been transformed into the problem ,,