Jökull - 01.01.2012, Síða 7

Sigurður Þórarinsson (1912–1983)
Figure 1. Isopach map of Hekla 1104, as mapped by S. Thorarinsson in 1939. At the time he thought this tephra
layer to be from Hekla 1300. – Kort Sigurðar Þórarinssonar (1939) af gjóskulaginu H 1104, sem þá var talið
vera úr Heklugosinu 1300.
Sigurður Þórarinsson came to the conclusion that
the valley had been laid waste by the Hekla erup-
tion in 1300. That eruption is well described in Ice-
landic annals: a fearful one, covering mid-North Ice-
land with ash and emitting volcanic bombs to ignite
farm houses kilometers away from the volcano. Based
on that, Hákon Bjarnason and Sigurður had in their
1940-article in Geografisk Tidsskrift assumed the up-
per light-coloured tephra layer in N-Iceland to corre-
spond to Hekla 1300. Such an eruption should have
left a thick and coarsely-grained layer in Þjórsárdalur,
18 km north of Hekla, and by 1939 Sigurður had
found no layer in the valley other than the one overly-
ing the farm ruins that might agree with the descrip-
tion of the 1300 Hekla eruption (Figure 1).
Sigurður’s conclusions, both regarding the mode
and the timing of the valley’s desertion, were ques-
tioned by historians who suggested that famine had
caused the settlement to be abandoned around 1050
A.D. The Icelanders had adopted Christianity in 1000
A.D., the valley had been quite densely populated,
so that in 300 years much more than 66 dead should
have been buried in the cemetery at Skeljastaðir. Sig-
urður remained unconvinced, pointing out that an un-
known number of skeletons were known to have been
removed from the cemetery in the past.
The Hekla eruption 1947–1948 was an eye-opener
for many Icelandic earth scientists. Sigurður noticed
that despite the first phase of the eruption having been
fairly violent, not much light-colored tephra was pro-
JÖKULL No. 62, 2012 5