Jökull - 01.12.2003, Side 27

The 1783–1785 Laki-Grímsvötn eruptions
Table 2. Timing of earthquakes, explosive activity and lava surges during the Laki-Grímsvötn eruptions in
1783–1785. – Atburðarás og einstakar goshrinur Skaftárelda og Grímsvatna 1783–1785.
Earthquakes Tephra Fall Lava surges Eruption episodes
jarðskjálftar öskufall aukið hraunrennsli goshrinur
19 May–8 June 8–9 June 12 June I
9–11 June 10–11 June 14 June II
13–19 June 14 June 18–20 June III
21 June3 ?
23–26 June
30 June 25–28 June 29 June IV
14 July 9-10 July 14 July
17–20 July 18–19 July3 18 July?2 V
29 July?
1–3 August 29–30 July 7 August VI
23–31 August 2 Sept. VII
7 Sept.
14 Sept. 3 10 Sept. VIII
26 Sept. 26 Sept. 4 IX
24–? Oct. 25 Oct. 3 25–29 Oct. X
2 Nov. ?
24 Nov. 24 Nov. 3 XI
Jan. 17843 XII
Feb. 17841
8 April 17843 XIII
14–25 Aug. 17841
4–26 May, 17853 XIV
1) These earthquakes were not directly linked to the Laki eruption or the volcano-tectonic episode at the Grímsvötn volcanic
system. See text for further discussion.
2) Steingrímsson’s description imply vigorous activity at the fissures on this day (i.e., B30), but does not directly indicate
increase in lava production and no lava surge was observed from the Skaftá River gorge.
3) Fires seen at or tephra fall from Austur-Landnorðursgjá (i.e., Grímsvötn volcano).
4) This lava surge never reached the lowlands, but increased lava production is indicated by cessation of flow in both
Hverfisfljót and Skaftá rivers.
from the farm Prestbakki it was observed to be most
intense in the lows between Kaldbakur and Lamba-
tungur in the northwest and Kaldbakur and Vothamrar
in northeast (B79).
Strong earthquakes were felt again on 26 Septem-
ber (A22). The emission of lava from the fissures in-
creased to such a degree that most rivers ceased flow-
ing, including the Skaftá and Hverfisfljót rivers (C47).
This was accompanied by, “An additional column of fire
and steam, which had been seen few times before [i.e., 18
July] far east-northeast from Síða, due north of Lómagnúp-
ur, but northwest from Öræfi district.” (B80, Figure 5g).
This activity continued at a diminishing rate until
24 October when intense earthquakes were felt in the
Fire districts and an acrid stench was emitted from the
east-northeast (A23). On 25 October, a huge column
of fire rose from the Austur-Landnorðursgjá and rain
containing sandy ash fell in the Síða district (B81–82).
The same day an intensive lava surge emerged from
the Hverfisfljót River gorge and in the following five
days the lava filled in the gap in between two earlier
flows (C48, Figure 5g). This was the last lava surge
JÖKULL No. 53, 2003 25