Jökull - 01.01.2019, Blaðsíða 41

Einarsson
Figure 3. Map of Katla and Eyjafjallajökull volcanoes with immediate surroundings. Data sources, see Figure 1.
– Kort af Kötlu og Eyjafjallajökli með helstu nálægum kennileitum. Gögn eru þau sömu og á 1. mynd.
The same day at 1 PM, heavy noises with large
cracking sound were heard, followed by terrible fire,
column of smoke and fumes, that issued from the
glacier north of Höfðabrekka, named Kötlugjá, . . . At
2 PM a flood of slush with a few icebergs flowed
rapidly from the glacier . . . At 3 PM the real jökul-
hlaup arrived with great haste . . . )
This large eruption was clearly preceded by rather
strong earthquakes, that caused distress in the near-
est areas (∼15–20 km) and were felt to a distance of
about 50 km. The precursory time was about 4 hours,
until an eruption began. The first jökulhlaup was de-
tected one hour after the eruption began, but the main
flood wave did not arrive until two hours after the
eruption.
1755: The most reliable account of this large eruption
is by Jón Sigurðsson who lived in Holt (Figures 2 and
3) in Mýrdalur, about 15 km SSW of Katla (Jónsson,
2018, p. 185–186):
„. . . Anno 1755 spjó Kötlugjá í Mýrdalsjökli.
Byrjuðust þau upptök föstudaginn þann 17. október
lítið fyrir hádegi með miklum jarðskjálftum, eins og
húsum vaggað væri, þar eftir þann dag til enda og
eftirkomandi nótt, svo margir voguðu varla inn í hús-
um að vera vegna hræringar jarðarinnar og kvíða
þeim að húsin mundu niður hrynja. Að kvöldi þess
sama dags þá dimma tók sáust eldingar títt fyrir
bregða sem skrugguljós, er gekk út ásamt með skjálfta
og hræringum jarðarinnar alla þá nótt . . . “
„. . . Nóttina eftir þann 17. október og svo um
daginn hljóp vatns- og jökulhlaupið úr svokallaðri
Kötlugjá fram af jöklinum, . . . “
. . . (Anno 1755 an eruption occurred in Kötlugjá
(Figure 3) in Mýrdalsjökull. The events began on
Friday, October 17, shortly before noon, with strong
earthquakes, like houses were rocked, that lasted till
the end of the day and the following night, so that
many did not dare to stay inside their houses because
of the movements of the ground and worries that the
40 JÖKULL No. 69, 2019