Jökull - 01.12.1975, Blaðsíða 73

Snjáflóð í febrúar 1975
2. febrúar féllu nokkur vot snjóflóð á Aust-
fjörðum, sjá liér að framan um snjóflóðin 2.
janúar hjá Snæhvammi.
Snjóflóð í mars 1975
hað telst vart til tíðinda, að 4. mars lokaði
snjóflóðsdyngja Óshlíðarvegi. Dyngjunni var
rutt burt með jarðýtu (útvarpsfrétt).
Hinn 10. mars var 10 stiga hiti í Ólafsfirði og
mikil leysing. Þá hljóp úr fjallinu utan við
Brimnes vott snjóflóð.
Dyngjan á veginum var 6—7 m þykk.
Lýkur hér snjóflóðaannál vetrarins 1974/75.
En gera má ráð fyrir, að eitthvað komi fram í
eftirleitum.
Að lokum þetta: Sérstakrar athygli er verð or-
sakaröðin, þ. e. a. s. röð veðrabrigðanna, sem
leiddu til snjóflóðanna, sem rækilegast er lýst,
þ. e. í Neskaupstað (20. des. 1974), ferlegu snjó-
flóðanna í Dalsmynni (um 13. jan. 1975) og á
Ljótsstöðum í sömu hrinu. Á öllum stöðunum
laumast inn lag af lognsnjó.
Sigurjón Rist.
S U M M A R Y
SNOW AVALANCHES IN ICELAND
1972-1975
Sigurjón Rist,
National Energy Authority
Hydrological Survey
The article is a continuation of the descrip-
tion of snow avalanches in Icelancl wliich ap-
peared in Jökull 1971. In the period 1972—1975
there are 180 reported snow avalances, whereof
100 fell in the year 1974. One of these fell on
the town Neskaupstadur in Eastern Iceland on
December 20, 1974 and caused death of 12
people, bringing the number of fatalities clue
to snow avalanches in this century up to a total
of 114 people.
It is clearly seen that the main snow aval-
anclies occur either during or immediately after
blizzards from north. Tlie climate is dominantly
oceanic, humidity is high and winds shift fre-
quently. Commonly mikl winds cause thawing
high up in mountains for several days. Sudden
cold spells tlien change the wet snow into hard
snow or almost ice and more snow is added. In
North Iceland and on the mountaineous west-
ern and eastern coasts, the northerly and north-
easterly winds are both humid ancl cold. There-
fore accumulation is dominantly on the south-
ern and western slopes of mountains.
The main swarms of avalanches came after
these prevailing periods of northerly winds:
1. Northwestern Iceland, after February 13,
1972
2. Northern Iceland, after December 19, 1973
3. Northwestern and Northern Iceland, after
the blizzard February 8—12, 1974
4. Northern and Eastern Iceland, after Dec-
ember 18, 1974
5. Northwestern, Northern and Eastern Ice-
land, after January 13, 1975
All these avalanches consisted of cascading dry
and windblown snow. Commonly it was report-
ed tliat 20—50 cm of snow had fallen in still
weather before the northerly wind began to
blow. Between the main swarms, occasional
local avalanches causecl by accumulation from
westerly winds were reported.
A number of wet avalanches is reported,
especially in Southeastern Iceland e.g. on Janu-
ary 2, 1975 and February 2, 1975.
No systematic observations of snow avalanches
are carried out in Iceland. Governmental plans
to improve this situation are in preparation. As
yet the observations are carried out by volun-
teers and amateurs in the country.
JÖKULL 25. ÁR 71