Fault segments are also typically arranged en echelon above the upward-propagating strike-slip fault. These structures, open fault segments containing a short tension crack, are termed compound cracks and the short tension crack that propagates from the tip of the fault segment is typically oriented 45? to the trend of the underlying fault. The fault segments are slickensided and striated a few centimeters below the ground surface continued displacement of the landslide causes the fault segments to open and a short tension crack propagates out of one or both ends of the fault segments. Fault segments are discontinuous strike-slip faults that contain the same sense of slip but are turned clockwise or counterclockwise from a few to perhaps 20? from the underlying strike-slip fault. Another common structure that forms above a developing strike-slip fault is a fault segment. The tension cracks are typically arranged en echelon with the row of cracks parallel to the trace of the underlying strike-slip fault. The simplest structure is a tension crack oriented at 45? clockwise or counterclockwise from the trend of an underlying right- or left-lateral strike-slip fault, respectively. Several types of structures are formed at the ground surface as a strike-slip fault, which is fully developed at some depth below the ground surface, propagates upward in response to displacement. Displacement along strike-slip faults commonly produces scarps scarps occur where local relief of the failure surface or ground surface is displaced and becomes adjacent to higher or lower ground, or where the landslide is thickening or thinning as a result of internal deformation. Fault surfaces are slickensided, and striations are subparallel to the ground surface. The strike-slip faults in landslides are nearly vertical but locally may dip a few degrees toward or away from the moving ground. We observed the formation of thwse strike-slip faults and associated structures at two large landslides in central Utah during 1983-1985. Large landslides are bounded on their flanks and on elements within the landslides by structures analogous to strike-slip faults.
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