Geologic Hazards of the State Route 9 Corridor, La Verkin City to Town of Springdale, Washington County, Utah

By: Tyler R. Knudsen and William R. Lund

Historically, the communities of La Verkin, Virgin, Rockville, and Springdale have been affected by a variety of geologic hazards. Recent damaging rock falls, riverine floods, recurrent flash floods and landslides, and problems associated with collapsible soil and expansive soil and rock demonstrate that the communities are vulnerable to geologic hazards, and that public officials require reliable hazard information as they plan for future growth. The Utah Geological Survey has prepared GIS-based information on the kinds and locations of geologic hazards that may affect existing and future development in the State Route 9 Corridor Geologic-Hazard Study Area (SR-9 study area). The SR-9 study area encompasses 97 square miles, and consists of a 2- to 8-mile-wide corridor centered on SR-9, that extends from the eastern part of La Verkin City to the Town of Springdale’s eastern boundary with Zion National Park.

This 13-page report includes nine 1:24,000-scale geologic-hazard maps that cover flooding and debris flows, rock fall, landslides, surface faulting, liquefaction, collapsible soil, expansive soil and rock, gypsiferous soil and rock, soil piping, erosion, and wind-blown sand. Each geologic-hazard map provides information on the data sources and techniques used to create the map, the nature and distribution of the hazard, and possible hazard-reduction measures.