Multiscale analysis of potential fields by a ridge consistency criterion: The reconstruction of the Bishop basement

摘要

We use a multiscale approach as a semi-automated interpreting tool of potential fields. The\uddepth to the source and the structural index are estimated in two steps: first the depth to the\udsource, as the intersection of the field ridges (lines built joining the extrema of the field at\udvarious altitudes) and secondly, the structural index by the scale function.We introduce a new\udcriterion, called ‘ridge consistency’ in this strategy. The criterion is based on the principle\udthat the structural index estimations on all the ridges converging towards the same source\udshould be consistent. If these estimates are significantly different, field differentiation is used\udto lessen the interference effects from nearby sources or regional fields, to obtain a consistent\udset of estimates. In our multiscale framework, vertical differentiation is naturally joint to the\udlow-pass filtering properties of the upward continuation, so is a stable process. Before applying\udour criterion, we studied carefully the errors on upward continuation caused by the finite size\udof the survey area. To this end, we analysed the complex magnetic synthetic case, known as\udBishop model, and evaluated the best extrapolation algorithm and the optimal width of the\udarea extension, needed to obtain accurate upward continuation. Afterwards, we applied the\udmethod to the depth estimation of the whole Bishop basement bathymetry. The result is a\udgood reconstruction of the complex basement and of the shape properties of the source at the\udestimated points.