GRAVITY APPROXIMATION AND INTERPRETATION OF A TWO‐DIMENSIONAL VERTICAL FAULT

The error in depth determination due to the thin plate approximation of a two‐dimensional vertical fault is investigated by the maximum slope method and the traditional [Formula: see text] method. We show here that although the gravity curves for thin and thick faults are not greatly different, faults with large throws have significant percentage errors in the depth to the central plane which warrant attention in precision interpretation. When the ratio of the throw of the fault to its mid‐depth varies from 1.5 to 1.9, the percentage error in depth increases from 10 to more than 16 percent. The maximum slope method for determination of depth gives larger percentage errors compared to [Formula: see text] measures. When the fault throw is large, a gradient method may be used to find the principal parameters of a two‐dimensional vertical fault. The method is theoretically free from any ambiguity and has other advantages which may facilitate precise interpretation. The thin plate approximation should be avoided in such cases.