Nomination of

SURTSEY – NOMINATION FOR THE UNESCO WORLD HERITAGE LIST
The Surtsey eruption column on November 16, 1963.
(Photo: Sigurður Þórarinsson).
pre-eruption water depth at the eruption site is
estimated to have been 130 ± 5 m.
Emerging on 15 November 1963, the island
grew rapidly in size. Two types of submarine,
hydromagmatic explosions were most common:
intermittent “cock's-tail” jets and a continuous
uprush of tephra. All of these explosions were
caused by hot magma being quenched in cold
sea-water. Calculations and measurements on site
indicate that the temperature of the magma was
1155°–1180° C, whereas the sea temperature in
this area is around 10° C.
A crescent-shaped crater of finely-bedded
tephra layers was built up between November
46
1963 and January 1964 (Fig. 2.18). On 31
January 1964, eruptions ceased in the eastern
vent (Surtur), which until then had been the sole
source of activity. On the following day, however,
eruptions broke out once more in a northeasttrending
fissure at the northwest side of that
crater, where another crescent-shaped tephra
crater soon formed (Surtungur), merged with the
eastern tephra crater, and finally achieved a
maximum height of 173 m above sea level.
During the winter of 1963–1964, storm waves
were severely destructive, carving broad
abrasional platforms into the loose tephra of these
two cones. On 4 April 1964, the eruption in
Surtungur switched to an effusive Hawaiian-type
lava phase. Clearly the island had at this point
grown large enough to isolate the vent from
inflowing seawater and thus protect the hot
magma from being quenched.
Between 28 December 1963 and 6 January
1964, explosive submarine activity was visible
about 2.0 km east-northeast of Surtsey. The
eruption fissure there, estimated as 250 m long,
created a submarine ridge called Surtla to over
100 m above the sea floor, but never raised it
above the water surface. Apparently nothing but
tephra was produced at this site.
At Surtsey, effusive lava activity continued in
the western crater until 17 May 1965, so that
gradually a flat lava shield was formed southwards
from the crater, while foreset-bedded
breccia was produced by submarine flow. The
lava shield was gradually stacked to a height of
100 m above sea level.
On 22 May 1965, explosive activity again
made itself apparent above the sea floor about
600 m east-northeast of Surtsey, creating this time
a small tephra island, Syrtlingur, which climaxed
at a height of 70 m and a maximum area of 0.15
km 2 . Since no lava was emitted to harden into
armour, this island was washed away by wave
action a few days after the eruption ceased, i.e.
on about 17 October 1965. Yet another island of
tephra, Jólnir, was created by explosive
submarine activity starting 1 km southwest of
Surtsey on 26 December 1965. At its maximum,
this island had a height of 70 m and an area of
0.28 km 2 . The eruption died out on 10 August
1966 and Jólnir had disappeared in late October
the same year.
Soon after the Jólnir activity died out, lava