Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 7 1 2007 10.5194/nhess-7-1-2007 http://www.nat-hazards-earth-syst-sci.net/7/1/2007/ http://www.nat-hazards-earth-syst-sci.net/7/1/2007/nhess-7-1-2007.html http://www.nat-hazards-earth-syst-sci.net/7/1/2007/nhess-7-1-2007.pdf 1 14 2007-01-10 Influence of tectonic folding on rockfall susceptibility, American Fork Canyon, Utah, USA J. A. Coe jcoe@usgs.gov E. L. Harp U.S. Geological Survey, Denver Federal Center, MS 966, Denver, CO, 80225, USA We examine rockfall susceptibility of folded strata in the Sevier fold-thrust belt exposed in American Fork Canyon in north-central Utah. Large-scale geologic mapping, talus production data, rock-mass-quality measurements, and historical rockfall data indicate that rockfall susceptibility is correlated with limb dip and curvature of the folded, cliff-forming Mississippian limestones. On fold limbs, rockfall susceptibility increases as dip increases. 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