Fault segmentation, fault linkage, and hazards along the Sevier fault, southwestern Utah

Theoretically, short normal faults link to form long faults and salients develop in the linkage zones. This project provides new data and interpretations on (1) normal fault linkage zones; (2) earthquake and landslide hazards; and (3) fold formation along the active Sevier fault, Utah. Geologic mapping, geometric analyses, geochronology, landslide evaluation, and stream history led to five conclusions. (1) Six principal faults linked to form the Orderville salient and connect the Mt. Carmel and Spencer Bench segments. Four relay ramps formed between overlapping faults. This multipartite linkage zone implies that simple models only imperfectly represent natural examples. (2) Two relay ramps contain rarely analyzed fault-parallel folds. These folds accommodate a downward decrease in space between faults. (3) Fluvial deposits indicate three downcutting stages of a south-flowing stream. Some slip along the Sevier fault occurred after the first two stages and tilted the deposits. (4) 570 ka basalt is offset ∼3 m. Thus, the young slip rate is 0.018 mm/yr. (5) Mechanical weathering processes or seismicity induced 14 landslides and similar future slope failures are likely