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VolcanoesVolcanoes

Exploding mountains?

But before that – a bit of revision from last week and I want EVERYONEEVERYONE to have a go!

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As __ is to ___ then ___ is to ? Why?As __ is to ___ then ___ is to ? Why?As H is to L, then F is to ? What is the rule?

F

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As B is to N, then D is to ? What is the rule?As G is to E, then A is to ? What is the rule?As V is to J, then Y is to ? What is the rule?

F

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Which is the Odd One Out? And why?Which is the Odd One Out? And why?Because it is not …….Because it is not …….

1. F, J, N 2. W, T, Z 3. U,L,R

F

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VOLCANOESVOLCANOESThe word "volcano" comes from the little island of Vulcano in the Mediterranean Sea off Sicily (Italy). Centuries ago, the people living in this area believed that Vulcano was the chimney of the god Vulcan ( he was the blacksmith of the Roman gods -- he made things out of metals).They thought that the hot lava pieces and clouds of dust erupting from Vulcano came from Vulcan's furnace as he made thunderbolts for Jupiter, king of the gods, and weapons for Mars, the god of war. In Polynesia the people attributed eruptive activity to the beautiful but wrathful Pele, Goddess of Volcanoes, whenever she was angry or spiteful. Today we know that volcanic eruptions are not super-natural but can be studied and interpreted by scientists.

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So, What is a volcano?Volcanoes are mountains, but they are very different from other mountains; volcanoes are built by the accumulation of their own eruptive products -- lava, bombs (hardened lava blobs), ashflows, and tephra (airborne ash and dust). A volcano is most commonly a cone shaped hill or mountain built around a vent that connects with pockets of molten rock (magma) below the surface of the Earth. The term volcano also refers to the opening or vent through which the molten rock and associated gases are expelled.

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As you heard last week…As you heard last week…

Volcanoes generally form along plate marginsEither where the plates are approaching each other and one is sliding under the other – destructive marginsOr where they are moving away from each other – constructive marginsThere are a few exceptions – called hot spots – where the magma bursts through a particularly thin bit of oceanic crust, for example in Hawii.

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Distribution of some of Distribution of some of the the

world’s major volcanoes world’s major volcanoesRing of Fire

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How do they form?How do they form?This one is forming on a destructive This one is forming on a destructive

plateplateAs the oceanic crust slips beneath the continental plate, some of the magma gets trapped above.This is force out through any crack it can find in the continental plate.Violà – you have a volcano!

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Which of these are Which of these are volcanoes?volcanoes?

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Types of volcanoTypes of volcano

They all were !

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Shield VolcanoesShield VolcanoesBroad, slightly domed-shapedMade of layers of frozen lavaMay be 100s of km across and have a large craterProduced by mild eruptions of large volumes of lavaNon-explosive eruptionsMauna Loa on Hawaii is a good example

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Cinder Cone VolcanoesCinder Cone VolcanoesMade of loose grainy cinders and no lavaSteep slope angleRather small size about 1 km across with a small craterFrequently occur in groups

Moderately explosiveExample: Paricutin (Mexico)

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Composite VolcanoesComposite VolcanoesMost are located adjacent to the Pacific Ocean (e.g., Fujiyama, Mt. St. Helens)Large, classic-shaped volcano (1000’s of ft. high & several miles wide at base) with a small craterComposed of layers of lava flows with layer of cinder and ash in between May have very explosive eruptions

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A composite volcanoA composite volcano

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Comparing sizesComparing sizes

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Which type is this?Which type is this?

A: Mount Rainier, Washington State in western USA

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Which type is this?Which type is this?

B: Paricutin, Mexico

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Which type is this?Which type is this?

C : Mauna Loa, Hawaii

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Which type is this?Which type is this?

D: Papua New Guinea

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Which type is this?Which type is this?

E: Popocatepetl, Mexico

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How did you do?How did you do?A = composite (Mount Rainier, WA)

B = cinder cone (Paricutin, Mexico)

C = shield (Mauna Loa, Hawaii)

D = cinder cone (Papua New Guinea)

E = composite (Popocatepetl, Mexico)

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Types of LavaTypes of LavaVolcanic eruptions may be quiet outflows of lava which are so peaceful that one can stand close enough to toss in pebbles or so explosively violent that they blow mountains apart and blast everything within a hundred miles to smithereens (not recommended for close observation).

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Two types of lava Two types of lava (they are called Pahoehoe and Aa in (they are called Pahoehoe and Aa in

Hawaii)Hawaii)

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Other volcanic landformsOther volcanic landformsCalderas

• Steep-walled depressions at the summit• Size generally exceeds 1 km in diameter

Example Santorini in Greece

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CalderaCaldera

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Volcanoes and climateVolcanoes and climate

Explosive eruptions emit huge quantities of gases and fine-grained debris into the atmosphere which filter out and reflect a portion of the incoming solar radiationExamples of volcanoes affecting climateMount Tambora, Indonesia – 1815Krakatau, Indonesia – 1883Mount Pinatubo, Philippines - 1991

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VOLCANIC ACTIVITY

ACTIVE - A volcano that has erupted in the recent past and is expected to erupt again. Any names?DORMANT - A “sleeping” volcano. A volcano that has not erupted in the recent past, but could erupt again. One in Yellowstone has not erupted fro 640,000 years BUT there are still earthquakes and steam emissions so it could!EXTINCT - A volcano that is not expected to erupt again. This is because there is no longer a source of magma. Castle rock in Edinburgh is an example

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There is a zondle on the There is a zondle on the wiki pagewiki page

But before that homework!

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HomeworkHomeworkChoose an active volcano (or at least one that has erupted in the last 20 years or so)Find out its name and where it is – I will send you a world map to move a X to the right spot.Find out which sort of volcano it is – shield, composite or cinder coneFind out 4 other things about it* You will also need to visit the Zondle on the zondle website to record a score – same rules as last week.

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Suggestions for your other 4 Suggestions for your other 4 thingsthings

A picture of your volcanoGeographic setting: – Is it on an island or in a mountain range? – Is it near towns or cities or is it isolated

When did your volcano last erupt? – what do you know about it?– Was the eruption hazardous to people? What

happened?

If the volcano erupts again, what are the possible hazards? Does it pose a threat now?What are 2 cool facts about your volcano?