1. Volcanoes
VCE Geography

2. Aims
Understand natural factors that create volcanic and other environments.
Understand how these natural factors interact.
Understand the geographic features of volcanic environments.
Demonstrate our spatial skills.
Mr O’Meara 2007
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3. What is a volcano?
There is very hot (molten) rock under the earth’s surface.
When the pressure builds up in the molten rock, lava and gas escapes through a fissure.
The word volcano applies to both the vent and the mountain left my the overflow.
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4. Volcano fact #1 The study of volcanoes is called volcanology.
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5. Volcano fact #2
More than 80% of the earth's surface comes from volcanoes.
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6. Volcano fact #3
The name volcano is said to have come from Vulcano, a volcanic island in the Aeolian Islands of Italy.
The name Vulcano originates from Vulcan, a god of fire in Roman mythology.
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7. Volcano fact #4
Seismographic monitoring, tiltmeters and surveillance by satellite all serve to predict activity in a volcano.
Gas and steam emissions can also indicate an impending volcanic eruption.
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8. Volcanic fact #5 There are three main types Tephra volcanoes
Shield volcanoes
Strato volcanoes
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9. What factors create environments?
We need to understand the structure of the earth.
The earth is made of many layers.
Starting at the middle they are
Crust (where we live) 0-35km
Upper mantle 35-60km
Mantle 60 – 2890km
A fluid outer core – 2890 – 5150km
A hard inner core –
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10. Activity Create a colour diagram of the layers of the earth.
This does not need to be to scale but does need to indicate distance with labels.
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11. Mr O’Meara 2007
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12. Magma vs. Lava Magma is molten rock under the ground.
Once it is expelled it is called lava.
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13. Caution: Contents May Be Hot
High temperatures and pressures are normal inside the earth.
This happens because of the natural decay of radioactive elements.
This makes the rock so hot it becomes fluid and gas. This is called magma.
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14. What are the geographic features of a volcano?
There are three main types of volcanoes.
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15. Strato Volcanoes The most common type.
Composed of solid lava flows alternating with pyroclastic material.
The lava flows act like a blanket for the rock layers.
They are steeper than a shield but not as steep as Tephra volcanoes.
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16. Shield volcanoes Composed of solidified lava flows.
The flattest type of volcano.
Can spread out over a wide area.
Slope often less than 10 degrees
For example Mauna Kea in Hawaii.
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17. Shield Volcano http://en.wikipedia.org/wiki/Shield_volcano
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18. Tephra volcanoes Composed of magma and associated rocks.
Steep sided slopes (around 30)
Rarely more than 300 metres high.
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19. Ring of Fire
Area of frequent eruptions and earthquakes around the Pacific Ocean.
Actually a horseshoe shape.
90% of the earthquakes.
Over 80% of the major volcanoes.
Includes over 160 active volcanoes.
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20. Ring of Fire
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21. Famous volcanoes - Mt Vesuvius
East of Naples, Italy
40°49′N, 14°26′E
The only volcano in Europe to have erupted in the last 100 years.
79AD eruption destroyed the towns of Pompeii and Herculaneum.
Between 15k and 30k people dead.
Today more than 3m people live close to Vesuvius making it a very dangerous volcano.
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22. Infrared Picture of Vesuvius
This is a night-time infrared photo of Mount Vesuvius in 1943.
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23. Famous volcanoes - Mt Vesuvius
It is a stratovolcano.
The last eruption was in 1944.
Destroyed several small villages and 88 US planes.
There is an emergency plan it place now which would involved moving 600,000 people to safety.
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24. Famous volcanoes - Mount St. Helens.
In Washington State, Pacific Northwest of the USA.
46°12′N, 122°11′W
Catastrophic eruption on May 18, 1980.
57 dead
250 homes lost
47 bridges
300km of highways.
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25. Famous volcanoes - Mount St. Helens.
It is a stratovolcano.
Is still active and has has small volcanic activities in the years between 1980 and now.
Has been in continuous eruption since 2004.
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26. What spatial skills are useful here?
Mapping skills, especially topography.
Topography (heights) is expressed using contour lines or different heights for different colours.
Understanding of region.
Understanding of movement.
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27. Useful links http://volcano.und.edu/ http://www.volcanoes.com/
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