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Publications - Occasional Papers

Avalanche Atlas: San Juan County, Colorado

INSTAAR Occasional Paper 17

1976, 232 pp.

[From the Introduction] The San Juan Avalanche Atlas was developed for the San Juan Planning Commission and the San Juan County Commissioners. It is intended to aid those in need of information concerning avalanche hazards related to land use planning.

The idea of an avalanche atlas is not a new one; the Swiss were interested in compiling a register of avalanches in the 1800’s. In North America, the first avalanche atlas was produced by the U.S. Forest Service for use by the Colorado Department of Highways in 1964 and is still being used for avalanche control, highway design, and highway maintenance. Similar atlases were developed in Washington State. The Washington State Department of Highways avalanche atlases are more detailed than the original Colorado atlas and include all avalanche paths affecting the highways.

The San Juan Avalanche Atlas attempts to take the next step in the evolution of the avalanche atlas in North America by providing more detailed information on the summary sheet than has been attempted in the past. Detailed technical data are supplied for each path and may be helpful to those interested in designing defensive structures for buildings, highways, etc. The information is not intended for critical engineering purposes, but rather as a guide for subsequent data gathering where necessary.

The atlas is a catalog of avalanche activity which has been observed from the late 1870’s through 1975 along highways 550 and 110 in San Juan County, Colorado. However, all known avalanche paths visible from these highways are not included; only paths for which data are readily available are cataloged.

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