ISLAND PROFILES
St. Lucia - Frequently Asked Questions
What is the Soufrière Volcanic Centre?
What is Sulphur Springs?
Is Sulphur Springs a volcano?
Is Sulphur Springs dangerous?
Since Sulphur Springs is constantly emitting steam does that mean that pressure
is being released from the volcano?
What are the Pitons?
Can the Pitons erupt?
When will the next eruption occur in Saint Lucia?
What is the Soufrière Volcanic Centre?
The Soufrière Volcanic Centre (SVC) is the only 'live' (likely to erupt again) volcano
in Saint Lucia. It is made up of a series of volcanic vents- which we see as mountains
and craters - near the town of Soufrière in the southe-western region of the island.
The SVC includes Gros and Petit Piton, Terre Blanche, Belfond, Mt. Gimie, Mt. Tabac
and a series of small explosion craters near Belfond.
All of these volcanic vents represent openings through which magma has erupted in
the past. Scientists currently believe the entire area is one single volcano (meaning
there is only one magma chamber beneath the area) with several volcanic vents or
openings.
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What is Sulphur Springs?
Many Saint Lucians mistakenly believe that Sulphur Springs is a volcano. Sulphur
Springs is actually a geothermal field (an area of hot springs and steam vents)
located within the much larger Soufrière Volcanic Centre. Geothermal systems, such
as Sulphur Springs, form when rainwater seeps into the ground where it is heated
by hot rock that has itself been heated by underlying magma (molten rock). The hot
water becomes buoyant, and rises back to the surface along cracks. In some places
the water is heated so much tht it rises as steam. Sulphur Springs, therefore, does
not represent the vent of a volcano.
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Is Sulphur Springs a volcano?
No, Sulphur Springs is not a volcano! It is a geothermal field (an area of hot springs
and steam vents) located within the much larger Soufrière Volcanic Centre. Although
some small phreatic (steam) eruptions may be produced at Sulphur Springs from time
to time, a future magmatic eruption could occur from anywhere within the Soufrière
Volcanic Centre.
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Is Sulphur Springs dangerous?
Sulphur Springs is part of the Soufrière Volcanic Centre (SVC). Scientists believe
there is a only a very slim chance of a magmatic eruption from the SVC in the next
100 years. However, there are serious ever-present hazards at Sulphur Springs of
which visitors should be aware.
Hot geothermal systems such as Sulphur Springs, emit large amounts of harmful gases.
Two of the more dangerous gases are carbon dioxide and hydrogen sulphide. Breathing
air with greater than 20% carbon dioxide can cause death. The
gas is heavier than
air and tends to accumulate in hollows in the ground, displacing the breathable
air. Since it is colourless and odourless, people and animals are unable to notice
that it is there and may suffocate. In areas of hot or cold soufriere people should
not enter low-lying hollows to remove dead animals in case there is a buildup of
carbon dioxide.
Hydrogen sulphide has a very strong and unpleasant smell, like rotten eggs. It is
extremely toxic. Breathing low concentrations causes headaches, fatigue, dizziness,
and irritation of the eyes and upper respiratory tract. Inhalation of hydrogen sulphide
can seriously aggravate sinus and respiratory systems and can cause bronchitis.
Other dangers at Sulphur Springs include landslides, boiling pools, and phreatic
(steam) eruptions. Extreme care should be taken when visiting Sulphur Springs!
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Since Sulphur Springs is constantly emitting steam does that mean that pressure
is being released from the volcano?
The Sulphur Springs geothermal system includes over 20 hot springs and fumaroles.
Contrary to popular belief these DO NOT act as a "safety valve" reducing the likelihood
of an eruption. In fact, the geothermal activity in this area indicates that hot,
molten rock exists not too far below the surface.
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What are the Pitons?
The spectacular Gros and Petit Piton are remnants of two large dacitic lava domes
that formed about 200-300 thousand years ago. They represent the steep inner core
("volcanic plug") of two lava domes after almost all the loose rubbly material that
normally aprons lava domes has been removed by efficient erosion due to the wind
and the sea.
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Can the Pitons erupt?
The Gros and Petit Piton are two volcanic vents that belong to the Soufrière
Volcanic Centre (SVC). Unlike many of the other vents of this volcanic centre (e.g.
Terre Blanche and Belfond) which are probably quite young and may erupt again, the
Pitons are known to be old (200 to 300 thousand years) and will not erupt again.
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When will the next eruption occur in Saint Lucia?
Given the complicated volcanic history of southern Saint Lucia and lack of age data
it is impossible to predict with certainty when the next magmatic eruption at the
Soufrière Volcanic Centre will occur. However, prior to the onset of a volcanic
eruption there will be precursor signs of activity, such as an increase in the number
and intensity of shallow earthquakes. The Soufrière Volcanic Centre is monitored very closely by the Seismic Research
Unit. Once precursory signs start to appear
they can be used to better forecast when and where the next eruption is likely to
occur.
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