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Volcanoes VCE Geography.

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Presentation on theme: "Volcanoes VCE Geography."— Presentation transcript:

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

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. Mr O’Meara 2007

4 Volcano fact #1 The study of volcanoes is called volcanology.
Mr O’Meara 2007

5 Volcano fact #2 More than 80% of the earth's surface comes from volcanoes. Mr O’Meara 2007

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. Mr O’Meara 2007

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. Mr O’Meara 2007

8 Volcanic fact #5 There are three main types Tephra volcanoes
Shield volcanoes Strato volcanoes Mr O’Meara 2007

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 – Mr O’Meara 2007

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. Mr O’Meara 2007

11 Mr O’Meara 2007

12 Magma vs. Lava Magma is molten rock under the ground.
Once it is expelled it is called lava. Mr O’Meara 2007

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. Mr O’Meara 2007

14 What are the geographic features of a volcano?
There are three main types of volcanoes. Mr O’Meara 2007

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. Mr O’Meara 2007

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. Mr O’Meara 2007

17 Shield Volcano
Mr O’Meara 2007

18 Tephra volcanoes Composed of magma and associated rocks.
Steep sided slopes (around 30) Rarely more than 300 metres high. Mr O’Meara 2007

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. Mr O’Meara 2007

20 Ring of Fire Mr O’Meara 2007

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. Mr O’Meara 2007

22 Infrared Picture of Vesuvius
This is a night-time infrared photo of Mount Vesuvius in 1943. Mr O’Meara 2007

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. Mr O’Meara 2007

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. Mr O’Meara 2007

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. Mr O’Meara 2007

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. Mr O’Meara 2007

27 Useful links
Mr O’Meara 2007

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