Introduction to special section: Active Fault‐Related Folding: Structural Evolution, Geomorphologic Expression, Paleoseismology, and Seismic Hazards

[1] Folds are one of the obvious and common manifestations of deformation of the continental crust, and attempts to understand the origins of these structures extend back to the very beginnings of geology as a discipline within the Earth Sciences. In particular, the relationship between faults and folds, and the manner in which fault-related folds grow and evolve through time, has been the subject of intense interest within the structural geology and tectonics communities for more than a century. Indeed, it did not take long after geologists understood the basic principles of stratigraphy and geological mapping [Lyell, 1830] to realize that subsurface structures could be delineated with some accuracy from surface observations, through the use of simple geometric rules [e.g., Rogers, 1856]. The fact that folding is associated with thrust faulting and mountain building was also recognized in the early days of structural geology, together with the necessity for large tangential displacements at the Earth’s surface across fold-thrust belts [Rogers, 1856; Moesch, 1867; Heim, 1878; Muller, 1878; Willis,