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The intent of this dataset is to depict liquefaction susceptibility from a M9 earthquake on the Cascade Subduction Zone within the Portland Water Bureau (PWB) service area and corridors along the conduits leading from the Bull Run watershed. Evaluating the potential for liquefaction and employing methods to mitigate its impacts were recognized as key factors for increasing earthquake resilience in the Oregon Resilience Plan (OSSPAC, 2013), as well as previous earthquake risk studies. Delineation of liquefaction-susceptible deposits in the PWB service area and estimating the magnitude of potential ground deformation is essential for the evaluation of potential damage from future large earthquakes in the Portland area. Mapping of liquefaction hazard allows for planning and mitigation prior to the next large earthquake and can be used for prioritizing emergency response following the earthquake.
This dataset represents liquefaction susceptibility for the City of Portland Water Bureau service area and the conduit corridors leading from the Bull Run Watershed.Geologic units susceptible to liquefaction have been attributed with a ranking, consisting of four ranked suceptibility classes ranging from Low to Very High. (A model was developed to account for five classes ranging from Very Low to Very High, however, no features fell within the Very Low classification.) Those with null "LiqExpl" values have been excluded from the analysis. Water bodies were removed. Complete methodology may be found in the draft report deliverable, Liquefaction and Lateral Spread Hazard, (InfraTerra, 2015), submitted to the Portland Water Bureau. |