Mason County

Seismic Soils & Liquefaction Risk

National Earthquake Liquefaction Hazard Reduction Susceptibility )l Program (NEHRP) Soils )l

Kitsap Kitsap

Lilliwaup Lilliwaup (! !(

Belfair Belfair (! !(

Hoodsport ! Hoodsport ( !(

Allyn Potlatch (! Allyn (! Potlatch !( !(

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Grapeview (! Grapeview !(

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Pierce Pierce

Shelton ^_ Shelton ^_

)l Thurston Thurston )l Liquefaction Susceptibility Soil Classification Soil classification data provided by the Washington State Department of Natural Resources - Liquefactrion data provided by the Washington State Department of Natural High Peat Division of Geology & Earth Resources. This data has been published at a scale of 1:100,000. Resources - Division of Geology & Earth Resources. This data is based solely Not Increasing Amplification of Ground Shaking Susceptible on surficial geology and has been published at a scale of 1:100,000. Moderate to High Bedrock The dataset identifies site classes for approximately 33,000 polygons derived from the geologic Moderate map of Washington State. The methodology chosen for developing the site class map required A liquefaction susceptibility map provides an estimate of the likelihood that soil B B-C C C-D D D-E E F Susceptible the construction of a database of shear wave velocity measurements. This database was created will liquefy as a result of earthquake shaking. Mason County depicts the relative Low to Moderate Rock Very Dense Stiff Soil Soft Requires by compiling shear wave velocity data from published and unpublished sources, and through Soil & Soft Rock Soil Site-Specific susceptibility to liquefaction from bedrock to areas of high susceptability. Areas Low Investigation the collection of a large number of shear wave velocity measurements from seismic refraction surveys underlain by bedrock or peat are mapped separately as these earthen materials Very Low to Low Date: July 10, 2017 conducted for this project. All of these sources of data were then analyzed using the chosen are not liquefiable, although peat deposits may be subjected to permanent Sources: Mason County GIS; methodologies to produce the statewide site class data. ground deformation as a result of earthquake shaking. Very Low WADNR