All photographs on this page © 1993 Hazel Blunt.

These pictures show the crater of the "Nisyros volcano"
or so the tourists are told...
In fact, the island of Nisyros is one big strato-volcano with
a large central caldera.  The volcano [island] was built up
above sea level about 66,000 years ago and may have
risen as high as 1000 metres 24,000 years ago.  The
main central cone of the volcano then collapsed during
a plinian eruption of dacite pumice, to leave the caldera.
Pumice from this eruption may be found in 100m thick
beds on the higher parts of the island.

The Stephanos blast hollow, with yellow sulphur deposits evident.

The caldera today lies 100m above sea level and is
walled by 150m to 400m high walls of andesite and
dacite lava rock.  The caldera itself is 3 kilometres
in diameter, but hard to recognize as five domes
(three large and two small) have risen inside the
caldera to cover half the floor area.  The largest dome
is the St Elias dome and is 600m high.  The St. Elias
dome is in fact the "mountainous" area on the left
of the top photograph, and in the background, in the
lower two photographs.  It is a young feature (a few
thousand years) as is said to be among the bulkiest
in europe.

During the last eruptions (so far), which occurred
in 1873 tuff cones were formed at the base of the
domes and a phreatic explosion created Stephanos,
a circular pit 300m in diameter and 25m deep.
The pit is the site of the only volcanic activity on Kos
at the moment in the form of sulphurous hydrothermal
fumeroles, mudpots and hot springs. Sulphurous
deposits can be seen on the crater walls in the above
pictures (the yellow stuff).  It is this blast pit
(Stephanos) that tourists from nearby Kos are
presented with as the "Nisyros Volcano".  So,
if you have ever been here and you thought you
were standing inside a 300m wide volcanic
crater, you were in fact, standing in a superficial
feature within a 3 kilometre wide volcanic crater.

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