Oraefajokull
is the highest mountain of the country, 2,110 m, and stretches to the
south of the middle of the ice cap Vatnajokull.
The terrain to its south reaches the elevation of about 100 m
above sea level.
The mountain is a topless strato volcano with a large, ice filled
caldera.
Its ice cover reaches down to the 1,800 m elevation and usually a
few precipitous cliffs of the peaks remain ice-free.
This strato volcano is considered to be the second most active in
Europe after Mt Etna in Sicily.
The ground diameter of the mountain is about 20 km and its ground
area about 400 km².
Its volume is close to 370 km³.
Prior to the enormous eruption in 1362 its name was Knappafell.
The
name of the inhabited area between the alluvial plains Skeidararsandur
in the west and Breidamerkursandur in the east, Oraefi,
dates back to the aftermath of the first eruption in
historic times.
That eruption almost totally destroyed the area and killed most
of the inhabitants and their livestock.
Afterwards the area looked like a vast desert, which is exactly
what the word Oraefi means.
The rhyolite peak Hvannadalshjukur rises about 300 m above the
caldera, which is about 5 km long and has an area of 12 km².
The average snow thickness added to the area annually is about 10
m, and the average precipitation up there about 5,000 mm, which exceeds
all other parts of the country.
A number of small glacier tongues slowly crawls down the indented
slopes of the mountain from about 1,800 m elevation.
The largest are Falljokull, Kviarjokull, Fjallsjokull and
Svinafellsjokull.
The
strato volcano has erupted twice during historical times, in 1362 and
1727. Scientists
consider the first eruption to be the largest pumice eruption in
historical times in the country, but another one took place about 2,800
years ago.
The volume of the tephra was estimated 10 km³, which corresponds
to about 2½ km³ of compact rhyolite.
The immense flood waves following the eruption swept most of the
farms away in the Little District as the area was called prior to the
eruption.
In the North ash fell on the ground and off the northwest coast,
boats had difficulties in getting through thick, floating patches of
pumice on the sea.
Thick patches of pumice from this eruption are all over the
present Oraefi area.
The
second eruption started in January 1727 and lasted almost a year.
Its fury was greatest during the first three days and the ash
fall so great, that it was impossible to distinguish between night and
day. Fewer
people and livestock were killed and no farms were destroyed, because
they stood on much higher ground than before.
The volume of tephra emitted was also much less than during the
first eruption.
The main flood wave ran eastwards past the parsonage Sandfell and
the farm Hof.
Signs of this natural catastrophe are still clearly visible in
the area.
Legends
about trips across the Vatnajokull ice cap in the ancient past exist.
No sources are available on the Oraefajokull until Sveinn Palsson
climbed it in 1794.
When he arrived at the peak and took a look around, he realized
how the glacier snouts were created and behaved.
He discovered, that the ice is a viscous mass, which slowly
moves
downward with gravity.
He also saw the layers of ashes from previous eruptions somewhere
in the country, and realized their meaning.
(Saga trail South Iceland) |