Jökull - 01.12.2006, Side 11

Avalanches in coastal towns in Iceland
in the central part of Northern Iceland and Austfirðir
is predominantly associated with winds from north-
east or north. In most cases, the avalanches occur
on south-facing slopes, which are the lee slopes dur-
ing northerly winds. This is, however, not always the
case, as e.g. in Siglufjörður, where the snow accumu-
lates in gullies when the wind blows along the moun-
tain slope. In some of the towns, avalanche hazard oc-
curs during both northerly and southerly wind direc-
tions in different parts of the town. There is, in some
cases, a relatively small difference between wind di-
rections which cause accumulation in an avalanche
starting zone and wind directions that erode the snow
from the mountainside. The critical conditions de-
pend on the aspect and form of the starting zones as
well as the fetch for snowdrift.
FUTURE WORK
Avalanche chronology and recording is a continual
and essential process. With the present effort of reg-
istration of avalanches, a good database will continue
to improve. At present, the main emphasis is only
on mapping for towns where the information is valu-
able for hazard mapping. Improved digital informa-
tion on the topography will gradually make it pos-
sible to create maps of all the available geographic
avalanche information in Iceland. This will provide
important background for hazard mapping for farms
and outdoor activities.
During the next years, the construction of perma-
nent avalanche protections will continue in most of
the towns. In spite of these protection measures, there
will always be a remaining risk. Avalanche warn-
ings and evacuations of residential areas will therefore
continue to be necessary.
Acknowledgements
This work would not have been possible without
the intensive work of employees at the avalanche sec-
tion at Veðurstofa Íslands forming the background for
this paper. We are grateful to Tómas Jóhannesson,
Magnús Tumi Guðmundsson, Helgi Björnsson, and
two anonymous reviewers for comments on the sci-
entific aspect of the paper and Amy Clifton, Barði
Þorkelsson and Matthew Roberts for their editing con-
tributions.
ÁGRIP
Í grein þessari er gefið yfirlit yfir skráð snjóflóð og
snjóflóðaveður á 13 þéttbýlisstöðum á Íslandi. Dreg-
in eru kort sem sýna útlínur á annað þúsund skráðra
snjóflóða fram til ársins 2003. Algengasti undanfari
mikilla snjóflóða er hvass vindur og mikil úrkoma.
Á norðanverðum Vestfjörðum, Mið-Norðurlandi og
Austfjörðum falla flóð oftast í norðlægum vindi en þá
safnast snjór hlémegin fjallanna í upptakasvæði sem
vísa móti suðri. Í undantekningartilfellum safnast um-
talsverður snjór í hlíðar samsíða vindátt og sums stað-
ar getur lítil vindáttarbreyting valdið mikilli breytingu
á snjósöfnun.
REFERENCES
Ágústsson, K. 1987. Snjóflóð á Íslandi veturna (Snow
avalanches in Iceland) 1984/85 og 1985/86. Jökull, 37,
91–98.
Arnalds, Þ., K. Jónasson and S. Sigurðsson 2004.
Avalanche hazard zoning in Iceland based on individ-
ual risk. Ann. Glac., 38, 285–290.
Björnsson, H. 1979. Snjóflóð og snjóflóðavarnir. Náttúru-
fræðingurinn, 49, 4, 257–277.
Björnsson, H. 1980. Avalanche activity in Iceland, climatic
conditions, and terrain features. J. Glaciol., 26(94),
13–23.
Björnsson, H. 2001. Veður í aðdraganda snjóflóðahrina á
Siglufirði. Veðurstofa Íslands - Greinargerð, 01018,
Reykjavík, 22 pp. (Icelandic Meteorological Office -
Report: Weather related to avalanche cycles at Siglu-
fjörður.)
Björnsson, H. 2002. Veður í aðdraganda snjóflóðahrina
á norðanverðum Vestfjörðum. Veðurstofa Íslands -
Greinargerð, 02019, Reykjavík, 75 pp. (Icelandic
Meteorological Office - Report: Weather related to
avalanche cycles in the northern part of Vestfirðir.)
Egilsson, J. G. 1995a. Snjóflóðið á Súðavík. Aðdragandi
og orsök. Fréttarit Landsbjargar, 1-95, 17–19.
Egilsson, J. G. 1995b. Snjóflóðið á Flateyri. Aðdragandi
og orsök. Fréttarit Landsbjargar, 5-95, 20–23.
Egilsson, J. G. 1996. Two destructive avalanches in Ice-
land. In: ISSW’96. Proceedings of the International
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