Quantitative rock-fall hazard and risk assessment for Yosemite Valley, Yosemite National Park, California April, 2012 Greg M. Stock, Ph.D., P.G. 1 , Nicolas Luco, Ph.D. 2 , Brian D. Collins, Ph.D., P.E., 3 , Edwin L. Harp, Ph.D. 2 , Paola Reichenbach 4 , and Kurt L. Frankel, Ph.D. 5 1 National Park Service, Yosemite National Park, El Portal, CA 95318 2 U.S. Geological Survey, Golden, CO 80225 3 U.S. Geological Survey, Menlo Park, CA 94025 4 Research Institute for Geo-Hydrological Protection (CNR-IRPI), Perugia, Italy 5 Georgia Institute of Technology, Atlanta, GA 30332 (deceased)