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<br />Table 3. (Cant.)
<br />
<br />Geologic Hamrds in the Crested Butte-Gunnison Area,
<br />Gunnison County, Colorado (Soule, 1976)
<br />Geologic Hamrds of the Glenwood Springs Metropolitan
<br />Area, Garjield County, Colorado (lincoln-DeVore,
<br />1978)
<br />Reconnaissance Geology and Geologic HamrdS Maps of
<br />the Canon City 7',1, Minute Quadrangle, Colorado
<br />(Beach, 1983)
<br />Debris-Flaw Hamrd in the Immediate VICinity of Ouray,
<br />Colorado Oochim, 1986)
<br />Surfidal-Geologic and Slope Stability Study of the
<br />DIJUgIas Pass Region, Colorado (Stover, 1986)
<br />Surfidal-Geologic Map of the Muddy Creek Landslide
<br />Complex, Gunnison County, Colorado, AprillS, 1986
<br />(Stover, 1986)
<br />
<br />Sources of Landslide Hazard Information
<br />Some of the organizations that produce or provide land-
<br />slide hazard information are listed in Table 4.
<br />
<br />Table 4. Examples of producers and providers of
<br />landslide-hazard information.
<br />
<br />American Institute of Professional Geologists
<br />American Society of Civil Engineers
<br />Association of Engineering Geologists, Rocky Mountain
<br />Section
<br />Colorado Department of Highways
<br />Colorado Geological Survey
<br />County extension agents
<br />Denver Museum of Natural History
<br />Educators (university, college, high school)
<br />Hazard researchers, interpreters, and mappers
<br />International Conference of Building Officials (Hazard
<br />Committee, Colorado Chapter)
<br />Journalists, commentators, editors, and other news
<br />professionals
<br />Local seismic safety advisory groups
<br />National Governor's Association
<br />Natural Hazards Research and Applications Information
<br />Center, University of Colorado
<br />Public information offices (federal and state)
<br />U.S. Army Corps of Engineers
<br />U.S. Bureau of Land Management
<br />U.S. Forest Service
<br />U.S. Geological Survey
<br />U.S. Soil Conservation Service
<br />
<br />24
<br />
<br />PRES NTING LANDSLIDE HAZARD
<br />INFO ATION BY MEANS OF MAPS
<br />
<br />Maps are useful and convenient method of presenting
<br />informatio on landslide hazard, They can present
<br />many kind and combinations of information at different
<br />levels of d tail. When used in conjunction with land-use
<br />maps, th are a valuable planning tool. Leighton (1976)
<br />suggests a three-stage approach to landslide hazard
<br />mapping. e first stage is regional or reconnaissance
<br />mapping, hich synthesizes available data and identifies
<br />general p blem areas. This small-scale mapping is
<br />usually pe ormed by a state or federal geological
<br />survey. next stage is comnnmity-level mapping, a
<br />more de d surface and subsurface mapping program
<br />in compl problem areas. Fmally, detailed site-specific
<br />large-scal maps are prepared. This three-stage
<br />approach mapping provides a quick initia1 approxima-
<br />tion of the general distnbution of hazardous areas and a
<br />basis for c nducting additional studies to quantify the
<br />extent of e hazard. It resources are limited, it may be
<br />more pm t to bypass regional mapping and concen-
<br />trate on S dying known areas of concern. .
<br />
<br />Region I Mapping
<br />Regional reconnaissance mapping supplies basic data
<br />for regio planning, for conducting more detailed
<br />studies at e community and site-specific levels, and
<br />for setting priorities for future mapping.
<br />These ps are usually simple inventory maps and
<br />are dire primarily toward the identification and
<br />delineatio of broad landslide problem areas and the
<br />conditions under which they occur. They concentrate on
<br />those geo . units or environments in which landslides
<br />have alrea occurred and in which additional
<br />move men are most likely. Such mapping relies heavily
<br />on photog ology (the geologic interpretation of aerial
<br />photograp ), reconnaissance field mapping, and the
<br />collection d syntheois of all available pertinent geologic
<br />data (le' ton, 1ll76).
<br />Regio maps are most often prepared at a scale of
<br />1:24,000, use high-quality U.S. Geological Survey
<br />topographi base maps at this scale are widely available
<br />and aerial hotos are commonly of a comparable scale.
<br />Other scal s commonly used include 1:50,000 (county
<br />series), 1: 00,000 (30 x 60 min.), and 1:250,000 (10 x 2 0
<br />quad.).
<br />
<br />Commu ity-Level Mapping
<br />Communi -level mapping identifies the three-
<br />dimensi limits of landslides as well as causative fac-
<br />tors. Sugg stions concerning land use, zoning, and
<br />building, well as recommendations for future site-
<br />specific' stigations are also made at this stage. In-
<br />vestigatio should include subsurface exploratory work
<br />
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