Jökull - 01.06.2000, Page 6

Holocene eruptions within the Katla volcanic system,
20 ˚
1 0 ˚ 0 ˚ 1 0 ˚
60 ˚
Katla
K 1625,1660,1755
K 1625,1755
K 1755 K 1625
K 1625
Kirkjubæjarklaustur
Höfn
Vík
0.1
0.5
1
3
0 50 km
Katla tephra layer
1625 AD
Isopachs in cm1
64°
00'
16° 00'18° 00'
Figures 2b and 2c. Dispersal of the 1625 Katla tephra.
b) isopachs of proximal and distal deposits on land.
c) occurrences outside Iceland (from Thorarinsson,
1980). – Dreifing gjósku í Kötlugosinu 1625. b)
jafnþykktarlínur gjóskunnar á landi. c) Staðir þar sem
gjóskufalls varð vart utan Íslands (Samkvæmt Sigurði
Þórarinssyni, 1980).
The date of 14 Katla eruptions is known to the
year (Table 1) and is approximately known for six oth-
ers. The time of the year is known for nine eruptions,
all of which began during the period May-November.
Small jökulhlaups in June 1955 and July 1999 may
have been caused by subglacial volcanism. Accord-
ingly, all Katla eruptions during the last 400 years
have begun during this time of the year. Although
four centuries are a short time in the lifespan of a
volcanic system, this implies that Katla eruptions are
more likely to begin during the spring-fall season than
in wintertime.
Table 1. Historical eruptions of the Katla system.
Tephra layers, thought to represent these eruptions
have been identified in soil sections around Mýrdals-
jökull. With the exception of K-1823, K-1245 and
the two 12th century layers all thepra samples have
been chemically analysed in order to verify their ori-
gin. Three eruptions, previously labelled K-1311,
K  1000 and K-x, have been dropped from the list
as the tephra layers representing them where found
to belong to other eruptions within the Katla system.
The latter two are part of the Eldgjá tephra. Dates:
 as summarized by Thorarinsson (1975),  Einars-
son et al. (1980),  Larsen (1984), Haflidason et al.
(1992),
Hammer (1980) and Zielenski et al. (1995).
– Gos á Kötlukerfi á sögulegum tíma. Gjóskulög,
sem talin eru mynduð í þessum gosum, hafa fundist
í jarðvegssniðum í nágrenni Mýrdalsjökuls. Öll nema
K-1823, K-1245 og 12. aldar lögin hafa verið efna-
greind til staðfestingar á uppruna þeirra. Þrjú gos,
sem áður voru talin til Kötlu, K ca. 1000, K-x og
K-1311, falla af skrá þar eð í ljós hefur komið að
gjóskulögin eru úr öðrum gosum á Kötlukerfinu. Tvö
þau fyrst nefndu eru hluti af gjóskulaginu úr Eld-
gjárgosinu.
Eruption Eruption Date Length Preceding
site year/cent. days years
Katla (1955  ) June 25 (37)
Katla 1918  Oct 12 24 58
Katla 1860  May 08 20 37
Katla 1823  June 26 28 68
Katla 1755  Oct 17  120 34
Katla 1721  May 11 >100 61
Katla 1660  Nov 03 >60 35
Katla 1625  Sept 02 13 13
Katla 1612  Oct 12 32
Katla 1580  Aug 11  80
Katla  1500

Katla 15. cent
Katla  1440
(24)
Katla 1416  (59)
Katla   1357  (95)
Katla 1262  17
Katla 1245  (66)
Katla  1179 
Katla 12. cent
Eldgjá 934/938
Katla  920 (16)
Katla 9. cent
JÖKULL No. 49 5