Jökull - 01.12.1961, Síða 23

SUMMARY:
THE VATNAJÖKULL EXPEDITIONS IN
JUNE AND SEPTEMBER 1961.
by SIGURDUR THORARINSSON.
In 1961 the Iceland Glacilogical Soiciety sent
two expeditons lo Vatnajökull. The first ex-
pedition lefl Reykjavik on June 10 and retur-
ned, on June 25. Participants were 11, using 3
wiesels on the glacier. This expedition had
three main aims. One group, lecl by S. Thorar-
insson and Magnús Jóhannsson was to carry
out the annual measurements of snow-accu-
mulation, especially in the Grímsvötn area, and
measure the rising of the snow- and water level
in the Grimsvötn depression betiueen Grídar-
horn and Depill. A group of geodecists, led by
Sleingrimur Pálsson, was to level with tachy-
meters a section 42 km in length from the
trig-point on Svíahnúkur eystri across Vatna-
jökull to a trig-point on Kverkfjöll eystri. This
group also intended to relevel a section level-
led in June 1959 from Nýjafell at the edge
of Tungnárjökull lo a point 3 km inside the
glacier front. The third aim was to carry out
gravimetric and magnetic measurements along
the levelled section between Svinahnúkur ancl
Kverkfjöll. This task was entrusted to Orn Gard-
arsson.
As during two previous Vatnajökull expedi-
tions (in spring 1959 ancl 1960) a postal service
was maintained in the Societies hut on Svía-
hnúkur. The postmark is Vatnajökull and a
specially appointed postmaster undertakes the
postal duties. The Society issues yearly 5000
numbered envelopes bearing a scene from
Vatnajökull and sells them in order to support
economically its researc.h activity. Noiu as be-
fore Grhnur Sveinsson from the Post Office in
Reykjavik was postmasler in the Svíahnúkur
hut.
Despite bad weather that lasted from June
13 to 18 the research program was carried out
satisfactorily. The levelling and the geophysical
measurements were completed by working day
and night when the weather conditions permit-
ted. The results will be published in this peri-
oclical.
Three pits were dug to about 6 m depth with-
in the drainage area of Grímsvötn. in the pit
dug at the iron mast erected by S. Rist on Oct.
9 1960, 6 km NE of the hut on Svíahnúkur and
1614 m above sea level, the winter accumulation
was 540 cm, water content 2760 mm. In o. pit
dug in the Grímsvötn depression 4 km IVNW
of Gridarhorn in about 1420 m height, the wint-
er accumulation was 610 cm, water content
3060 mm and in the third pit, dug on Kverk-
fjallahryggur in the Svíahnúkur-Kverkfjöll
section, 11.5 km from Sviahnúkur and in 1670 m
height the winter accumulation luas 553 cm,
water content 2800 mm. At the iron mast er-
ected by Rist on Oct. 6 1960 7.5 km NW of
Pálsfjall and in about 1300 m height, the acc-
umulation was 377 cm, water content about
1900 mm.
At Depill situated at the xuestern edge of the
Grímsvötn depression, the zuater level, as meas-
ured on June 17, 1961, had risen 24 m since
June 12 1960 or an average 6.5 cm per day.
The autumn expedition lefl Reykjavík Sept.
9 and returned Sept. 17. Participants were 8
(cf. Fig. 9) using 2 tuiesels. Leader was S. Thor-
arinsson. On the Society’s invitation Dr. Valter
Schytt, the renoiuned Swed.ish glaciologist, join-
ed this expediiion.
Below the firnline the Tungnárjökull was
much easier to traverse than the previous
autumn, tuhen it proved impossible to Iraverse
with luiesels.
At the iron mast NW of Pálsfjall the net
ablation June 12. — Sept. 11 was 173 cm. At
the mast 6 km NE of Sviahnúkur eystri the
net ablation June 19. — Sept. 12 was 69 cm.
There the average spec. weight, of the winter
layer 1960/61 had increased from 0.51 to 0.58;
in the lowermost 2.5 m of the layer it had in-
creased from 0.49 to 0.59.
Both iron masts tuere heiglitened so tlmt
they reached 858 (Grímsvötn) and 584 cm
(Pálsfjall) above the firn level when left.
At Depill the water level measured on Sept.
11, had risen only 2 m since June 17 or on
average 2.3 cm per day.
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