Estimating strain from fault-slip using a line sample

A method is presented that enables data for faults with different orientations and displacements, measured along a single straight line, to be used to estimate the magnitudes and orientations of the principal strain axes. The method combines two well-established techniques. When sampling along a line, the probability of intersecting a fault is affected by its orientation. This sampling bias may be minimized by the use of a weighting, w = 1/cos ?, where ? = angle between the perpendicular to the fault and the sample line. The displacement gradient and Lagrangian strain tensors may then be used to describe the deformation with respect to the undeformed state. The method can also be applied to such structures as veins and stylolites. As an example of the use of the method, 1340 normal faults have been measured along a 6 km length of Cretaceous chalk cliffs at Flamborough Head, Humberside, U.K. Consistent strain estimates have been obtained for different portions of the cliff.