Avalanche zoning in alaska, U.S.A.

Abstract

Over 30% of Alaska’s 586 400 squares miles (1 518900 km2) is subject to snow-avalanche activity. For a state-wide avalanche hazard evaluation, Alaska has been divided into six major snow— avalanche regions on the basis of topography, climatological data, dominant snow—pack conditions, and typical avalanche activity. They are: Arctic Slope, Brooks Range, Western, Interior, South—central, and South—east.Mountainous terrain was studied at scales of 1 : 250 000 and 1 : 1 584000; final compilation was at a scale of 1 : 2 500 000. Regional snow—pack and climatic conditions were cross—correlated with relief zonation of each avalanche region to produce a map of Alaska's provisional snow—avalanche potential.Most of the mountainous areas in the South—central and South—east regions, because of their northern latitude, closeness to large masses of water, and large orographic and cylonic weather processes, are susceptible to major avalanche activity. For areas near population centers, the potential avalanche terrain has been identified from data on known and suspected avalanche activity through air photographs, terrain analysis, and documented snow—avalanche occurrences compiled at scales of 1 : 250 000 and 1 : 63 360.The state—wide regional data compilation and study are initial steps toward avalanche zoning in Alaska. Local land—use planning and detailed investigations are needed to establish effective natural—hazard zoning in municipal areas as related to snow avalanche activity.

Mountain hazards: reducing vulnerability by adapted building design

“…Accordingly, the traditional engineering approach of mitigating hazard processes directly in the release areas of individual catchments, e.g., by designing snow rakes in avalanche starting zones and retention barriers in torrent Total costs of the prototype reinforced building ?8 channels, were supplemented by technical structures in the run-out areas, e.g., retention basins (Holub and Fuchs 2009). However, it had been shown that such structures have to be supplemented by passive mitigation concepts such as hazard mapping to reduce an exposure of elements at risk to hazards, a hypothesis that is rooted in very influential earlier works from the practitioners side (e.g., de Crécy 1980;Frutiger 1980;Hackett and Santeford 1980;Hestnes and Lied 1980;Ives and Plam 1980). Nevertheless, neither conventional structural measures, which influence both, the magnitude and frequency of events, nor passive mitigation concepts can guarantee reliability and complete safety.…”

Geologic hazards in and near the northern portion of the Bristol Bay Basin

“…The study area is in the western snow-avalanche region of Alaska, in which the predominant avalanche activity in mountainous areas may be characterized by dry, hard wind slabs on bimodal lee slopes with some wet loose snow and slush-flow avalanches in spring (Hackett and Santeford, 1980). However, because mountainous terrain is virtually absent in the study area there is limited snow-avalanche potential, and that only in localized areas of steeper slope.…”

Geologic hazards in the Yakataga planning area, southeastern Alaska: an overview

“…High relief combined with heavy, wet snowfall, cold temperatures, and erratic strong winds in this area create conditions favorable for major snowavalanche activity (Hackett and Santeford, 1980). Earthqilakes can trigger large slope failures and snow avalanches, as they did in the mountains west of Icy Bay during Ule 1899 events (Tarr and Martin, 1912).…”