Avalanche management

1
Avalanche management
New Zealand South Island training programme
with Otago Polytechnic
2
(No Transcript)
3
Avalanches are common on steep, snow-covered
mountain slopes and play a significant role in
landscape evolution. Although most avalanches
occur in remote locations, a few affect people
directly by causing injury or death. Statistics
show that most skiers or climbers caught in
avalanches trigger the slide themselves.
Avalanches also delay travellers and often cause
damage to property. The cost of highway closures,
avalanche defense structures and avalanche
control can be high. For example in western
Canada the annual bill for operational control
and forecasting is about 10 million.
4
Avalanche debris is typically well compacted and
hard as a result of frictional heating and work
hardening. Heavy equipment is needed to clear
avalanche debris, which may also contain rocks
and trees.
5
(No Transcript)
6
(No Transcript)
7
Avalanche Risk Assessment - Longyearbyen
8
www.unis.no/RESEARCH/GEOLOGY/Geo_research/Ole/Snow
Avalanches.htm
Car hit by the wind blast associated with a large
loose snow avalanche and subsequently folded
around a tree.
9
Cornice formed in upper Vandledningsdalen, late
June 2000. The snow accumulated by snow drift
across the mountain plateau by prevalent SE
winter winds. The height from the valley bottom
to the mountain plateau above is about 70 m
10
Avalanche boulder tongue in Endalen, Spitsbergen,
Svalbard, August 2000. The avalanche track is
seen as a light-colored deposit of debris,
extending from the small valley in the upper
right to the lower left corner of the photograph.
The mountain rises to about 580 m asl., while the
valley bottom is at about 200 m asl. This
avalanche track extents all the way to the river
plain, signaling even the valley bottom beyond to
be within the avalanche risk zone during winter.
11
Buildings on Haugen destroyed by a wet snow
avalanche from Vandledningsdalen, June 1953. By
this event 3 persons were killed and 30 other
persons were injured. The old hospital was
destroyed and several other buildings damaged.
Another wet snow avalanche occurred in 1989,
resulting in loss of property but no casualties.
Avalanche defense structures have since been
constructed at the mouth of Vandledningsdalen
12
(No Transcript)
13
Avalanches often follow the almost same path from
year to year. Local knowledge on high- and low
risk zones may with considerable success be used
to locate buildings and other structures in the
landscape. The picture shows an example from
Switzerland.
14
www.eng.ucalgary.ca/Civil/Avalanche/Civil_Site/ava
lanche.htm
15
This house in Davos, Switzerland has been
designed and reinforced to mitigate the avalanche
risk to the occupants. The windows have strong
shutters and the walls are reinforced. The
kitchen and garage of such houses are often
placed facing the avalanche slope. The rooms
where people spend the most time, such as the
bedrooms, are located on the opposite side of the
house. Some houses have a bunker in the basement
for temporary occupancy during extreme storms.
Precautionary evacuations are also used in areas
where destructive avalanches have long return
intervals such as 100 years.
16
Gas exploder in French Alps. The exploder is
filled with propane and oxygen from cylinders in
a control shelter (not shown). When ignited by a
spark plug in the exploder, the explosion
releases unstable snow near the exploder. There
are approximately 20 of these exploders in Canada.
17
The berm on the left side of the photo diverts
avalanches parallel to the highway through Rogers
Pass in Glacier National Park. The height and
curvature of the berm are determined from
calculations of avalanche motion.
18
Snowpack support structures near Andermatt,
Switzerland. When constructed in avalanche
starting zones, such structures reduce the
frequency of large dry slab avalanches. These and
similar wooden structures can be used to mitigate
large avalanches while the forest regrows.
19
Summary of Hazard Management Prediction /
Forecast Education Planning /Zoning Protection Aba
tement