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Vulcanicity
Volcanism
Volcanism is the eruption of magma onto the surface of the Earth. It is an endogenous process caused
by the movement of plate tectonics. Magma under the crust is under very great pressure.
When folding and faulting occur, cracks or fractures appear. These are lines of weakness. When…

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Types of lava
(BADR)

Basaltic (Basic) lava:

Erupts primarily from shield volcanoes, fissure systems, scoria cones, and spatter cones.
Most common at along spreading ridges (constructive margins).
Dominated by Iron and Manganese and low in silica content (48% - 52%).
Eruption is fluid and free-flowing - high water contents.
Temperature…

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Types of eruptions




Icelandic Basaltic Lava flows gently from fissures
Hawaiian Basaltic Lava flows gently from central
vent
Strombolian Basaltic Frequent, explosive eruptions
of tephra and steam.
Occasional, short lava flows.
Vulcanian Basaltic, andesitic and rhyolitic Less frequent, but more violent
eruption of gases, ash and
tephra.
Vesuvian Basaltic, andesitic…

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o Eruption: gentle, persistent (A'a flow) - creates extensive lava Plateaus.
o Has a long, linear vent ­ fairly flat surface.
Lava Plateaux
A wide area of solidified lava that can be up to 1km thick covering large
surface areas. They are multi layered because of repeated lava flows and…

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Minor extrusive feature
(GMHFS)
Geysers
o An intermittent turbulent discharge of superheated water
ejected and accompanied by a vapour phase/hot springs
where the water erupts i.e. The Strokkur Geyser in
Iceland & Old Faithful in Yellowstone National Park
USA.
o Formed in areas of intense volcanic activity.
o Water heated…

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Intrusive Volcanic Feature
((DSLB))
INTRUSIVE volcanic features occur due to lava being intruded into the lithosphere or rock, they cool
and solidify into rocks and are later exposed at the land surface as erosion and weathering DENUDES
the land downwards. The majority of volcanic features are actually intrusive, most volcanic…

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o Larger-scale intrusive landform, massive in size and depth formed deep below the
surface
o Forms when large masses of magma cool and solidify. As the
magma cools slowly, large crystals are formed in the rock (e.g.
granite).
o Batholiths are often dome-shaped and exposed by later
erosion. This is…

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What are Fold Mountains?
Fold Mountains are formed along plate boundaries.
Over millions of years, thick sediments were deposited in huge depressions called geosynclines.
Rivers carried sediments and deposited them into the depressions. The sediments were
compressed into solid sedimentary rocks such as sandstone and limestone.
The plates moved together,…

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It's not possible to prevent earthquakes and volcanic eruptions. However, careful management of
these hazards can minimise the damage that they cause. Prediction is the most important aspect of
this, as this gives people time to evacuate the area and make preparations for the event.
Predicting and preparing for volcanoes…

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o Funds need to be available to deal with the emergency and a good communication
system needs to be in place.

Preventing an eruption
Currently, it is impossible to prevent a volcanic eruption, but it is possible to keep damage to a
minimum. In 1973, citizens of Iceland poured cold…

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