Earthquake-induced ground failure hazards in the Reno-Sparks region, Washoe County, Nevada

Abstract

Earthquake-induced ground failure hazards associated with liquefaction and landsliding are identified and mapped throughout the urbanized and developing areas of the Reno- Sparks region. Separate maps, produced at 1:62,500 scale, identify areas susceptible to liquefaction and landsliding. Liquefaction susceptibility mapping is based on a compilation of more than 500 bore holes. Where bore hole density is sufficient, the critical acceleration to cause liquefaction during a M 7.5 earthquake, values were contoured to yield the map pattern. The critical accelerations refer to acceleration at the ground surface, not bedrock accelerations. The potential for liquefaction at a site is strongly influenced by the properties of the soil underlying the site and resonance effects. The influence of these local site conditions are not included in this study. Where data density is sparse or nonexistent, liquefaction susceptibility mapping is based on published geology and groundwater conditions. Landslide hazards addressed in this study include: 1) rockfall, 2) rotational rock slides and 3) shallow soil slides. These three slide types are considered the most pertinent to discussions involving earthquake induced slides given the geologic, climatic and geomorphic conditions of the Reno-Sparks region.