This datalayer contains polygon boundaries and minimal codes for significant seismic hazard areas of King County, Washington. It is derived from the coverage SEISM, a working (maintenance) copy of the Sensitive Areas Ordinance GIS data set SEISMSAO. As of October 1997, the content of the two coverages is the same.
The King County Sensitive Areas Ordinance (SAO) defines significant seismic hazard areas as those areas of King County subject to severe risk of earthquake damage as a result of seismically induced settlement or soil liquefaction. These conditions occur in areas underlain by cohesionless soils of low density, usually in association with a shallow groundwater table.