Geometric relations of dip slip to a faulted ground surface: new nomograms for estimating components of fault displacement

Abstract

The throw, heave, and dip-slip components of displacement on a fault scarp can be estimated from two easily collected field measurements when fault dip is known or assumed: the vertical separation and slope angle of the original ground surface displaced across the fault. Nomograms allow graphical determination of slip components for cases where fault dip is in the same or in an opposite direction as the slope of the ground surface. The technique has several advantages over a previous method that requires three field measurements; those of scarp height, scarp slope angle, and the slope of the original ground surface. The geometric relations of a fault scarp illustrate that although differences between throw and vertical separation of the ground surface are small in the cases of steep fault dips or flat ground surfaces, these differences can be greater than commonly assumed.