Jökull - 01.06.2000, Blaðsíða 3

Guðrún Larsen
Mýrdalsjökull
Ice Cap
Katla
K
ÖE
S
Skóga- and
Sólheimasandur Mýrd
alssa
ndur
KA
TL
A
VO
LC
AN
IC
SY
ST
EM
El
dg
já
Fi
ss
ur
e
Vatnajökull
Ice Cap
Vík
10
0
30
0
50
0
Volcanic Zone
K: Kötlujökull
S: Sólheimajökull
E: Entujökull
Ö: Öldufellsjökull
Caldera rim
Crater row / volcanic fissure
1918 eruption site
1955 depressions
0 10 20 km
18° 00'19° 00'
63°
40'
Figure 1. The Katla volcanic system in S-Iceland (shaded) as defined by Jakobsson (1979). Subglacial caldera
below Mýrdalsjökull ice cap as defined by Björnsson et al. (1993 and this volume). Inset: Location map of Ice-
land and volcanic zone. – Kötlueldstöðvakerfið (skyggður flötur) samkvæmt Sveini Jakobssyni (1979). Útlínur
öskjunnar eru dregnar samkvæmt Helga Björnssyni o.fl. (1993 og grein í þessu hefti). Gígar og gígaraðir eru
dregnar eftir loftmyndum frá Landmælingum Íslands.
Transitional alkali basalts with a narrow composi-
tional range dominate both the Holocene and Pleisto-
cene volcanics (Jakobsson, 1979; Meyer et al., 1985).
A shallow, infrequently replenished magma chamber
was postulated by the latter to explain the petrology of
the products. The existence of a low velocity anomaly,
interpreted as a shallow subcaldera magma cham-
ber, has recently been demonstrated (Guðmundsson
et al., 1994). Two eruptions have occurred within the
Katla system every century on average during the
last 1100 years (Thorarinsson, 1975; Larsen 1993).
Only the Grímsvötn and Veiðivötn volcanic systems
have higher eruption frequency (Thorarinsson, 1974;
Björnsson and Einarsson, 1990; Larsen et al., 1998).
2 JÖKULL No. 49