CONTRIBUTION DES ABAQUES BILOGARITHMIQUES A L'INTERPRETATION GRAVIMETRIQUE*

Among the means of comparing experimental anomalies with theoretical ones, logarithmic master curves constitute a very practical procedure. Theoretical anomalies for a large number of simple structures have been calculated once for all and drawn on logarithmic scale, in a condensed and handy way. The experimental anomalies are all represented in the same manner, and comparison with the master curves reveals one or several gravimetrically valid structures. If many master curves are available, various hypotheses can be put to the test.

Logarithmic master curves have the advantage of taking into account the whole of the anomaly to be interpreted. For each structure they furnish all parameters defining it: depth, dimensions, density contrast. As master curves can be used very quickly, several hypotheses for each anomaly can be tried out in a very short time, so as to associate a group of possible structures with the anomaly. This seems to be the best way of coping with the indeterminateness of the gravimetric method.