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ii. Hillsides intersecting geologic contacts with a relatively permeable sediment overlying <br />a relatively impermeable sediment or bedrock; and <br />iii. Springs or groundwater seepage. <br />c. Areas that have shown movement during the Holocene epoch (from 10,000 years ago to <br />the present) or which are underlain or covered by mass wastage debris of this epoch; <br />d. Slopes that are parallel or sub-parallel to planes of weakness (such as bedding planes, joint <br />systems, and fault planes) in subsurface materials; <br />e. Slopes having gradients steeper than eighty percent (80%) subject to rock fall during <br />seismic shaking; <br />f. Areas potentially unstable as a result of rapid stream incision, stream bank erosion, and <br />undercutting by wave action, including stream channel migration zones; <br />g. Areas that show evidence of, or are at risk from snow avalanches; <br />h. Areas located in a canyon or on an active alluvial fan, presently or potentially subject to <br />inundation by debris flows or catastrophic flooding; and <br />i. Any area with a slope of forty percent (40%) or steeper and with a vertical relief of ten (10) <br />or more feet except areas composed of bedrock. A slope is delineated by establishing its <br />toe and top and measured by averaging the inclination over at least ten (10) feet of vertical <br />relief. <br />3. Classification: Erosion hazard areas – areas containing soils that may experience significant <br />erosion, including: <br />a. Slopes forty percent (40%) or steeper with a vertical relief of ten (10) or more feet, except <br />areas composed of consolidated rock. <br />b. Concave slope forms equal to or greater than fifteen percent (15%) with a vertical relief of <br />ten (10) or more feet, except areas composed of consolidated rock. <br />c. Channel migration zones: Areas within which the stream channel can reasonably be <br />expected to migrate over time as a result of normally occurring hydrological and related <br />processes when considered with the characteristics of the river and its surroundings. Such <br />hazards are characterized by abandoned channels, ongoing sediment deposition and <br />erosion, topographic position, and changes in the plant community, age, structure and <br />composition. <br />4. Classification: Seismic hazard areas – lands subject to severe risk of damage as a result of <br />earthquake induced ground shaking, slope failure, settlement, soil liquefaction, or surface <br />faulting the following classifications shall be designated as seismic hazard and are subject to the <br />requirements of this Section. <br />5. Classification: Volcanic hazard areas – areas subject to pyroclastic flows, lava flows, debris <br />avalanche, inundation by debris flows, mudflows, or related flooding resulting from volcanic <br />activity. There are no active or dormant volcanoes located within Kittitas County; <br />howeverhowever, Mount Rainer and Mount St. Helens are relatively near. Hazards to Kittitas <br />County residents from these volcanoes are limited to ash deposition. <br />6. Classification: Mine hazards areas – areas underlain by abandoned mine shafts, secondary <br />passages between shafts tunnels, or air vents. Mine hazards include subsidence, which is the <br />uneven downward movement of the ground surface caused by underground workings caving in; <br />contamination to ground and surface water from tailings and underground workings; <br />concentrations of lethal or noxious gases; and underground fires. <br />7. Mapping: The approximate location and extent of geologically hazardous areas are shown on <br />maps maintained by the County. These maps shall be advisory and used by the Administrator to