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<br />002830 <br /> <br />aerial photos are commonly flown at a comparable scale. Other scales commonly <br />used include 1:50,000 (county series), 1:100,000 (30 x 60 min.), and 1:250,000 <br />(10 x 20 quad.). <br /> <br />COMMUNITY-LEVEL MAPPING <br /> <br />This level of mapping identifies the three-dimensional limits of landslides, <br />as well as causative factors. Suggestions for land use, zoning, building, and <br />recommendations for future site-specific investigations are also made at this <br />stage. Investigations should include subsurface exploratory work since the <br />product will be a large-scale map with cross sections (Leighton, 1976). Map <br />scales vary, but range from 1:1,000 to 1:10,000. <br /> <br />SITE-SPECIFIC MAPPING <br /> <br />This level of investigation is concerned with the identification, analysis, <br />and solution of actual site-specific problems. This level of investigation is <br />usually undertaken by private consultants for owners proposing site <br />development and involves a detailed drilling program with downhole logging. <br />sampling, and laboratory analysis. This provides the necessary information <br />for design and construction (Leighton. 1976). Map scales vary. but are <br />usually not larger than 1:50. <br /> <br />TYPES OF MAPS <br /> <br />The main types of landslide maps are 1) landslide inventories, 2) landslide <br />susceptibility maps. 3) terrain analysis maps. 4) landslide hazard maps. and <br />5) risk maps. <br /> <br />Landslide Inventories <br /> <br />These maps identify areas that appear to have failed by landslide processes <br />including debris flows and cut-and-fill failures. The level of detail of <br />these maps ranges from simple reconnaissance inventories that only delineate <br />broad areas where landsliding appears to have occurred to complex inventories <br />which depict each landslide. classify it as to type. and show scarps, zones of <br />erosion and accumulation, active versus inactive slides, geological age, rate <br />of movement, and other pertinent data on depth and kind of materials involved <br />in sl iding (USGS. 1981; Brabb, 1984). <br /> <br />- 14 - <br />