Gravity Nomographs for Fault Solutions

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The gravity field over high angle faults is characterized by linear zones of high gravity gradient. The total anomaly caused by a fault, the difference in gravitational attraction between the high and low sides of the gradient zone, is a function of throw of the fault. An equation that expresses this relationship provides a graphical solution of fault displacements when put into the form of a nomograph. The horizontal gradient of the field in a direction perpendicular to the strike of the fault is related to the depth of the plate produced by faulting. The gradient is obtained by differentiation and provides a graphical solution to the mean depth of a faulted plate when put into the form of a nomograph. Two measurements made on the gravity map, the total anomaly and maximum gradient, and the use of nomographs are all that is necessary to solve fault problems when the geometry of the structures is near ideal and the assignment of densities is realistic.