LC1DINV : laterally-constrained 1-D inversion for processing airborne EM data

BGS has recently developed jointly with GTK (Geological Survey of Finland) an advanced airborne geoscience capability and has commenced extended airborne surveying of Northern Ireland with other areas soon to follow. Large multi-frequency electromagnetic data sets comprise an important part of these surveys. In order to aid the interpretation of these data sets, we have developed “LC1DINV”, a laterally constrained one-dimensional inversion algorithm. LC1DINV inverts for the resistivities and thicknesses of a few (two or three) horizontal layers using a regularised conjugate gradient optimisation routine. The inverse problem is stabilised through the use of lateral constraints that ensure that model parameters change smoothly in the horizontal direction while preserving our ability to distinguish layer boundaries. Tests on synthetic models confirm the stability and efficiency of the method.