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It’s Unbe-lava-bly awesome VOLCANOES. PREPARE TO BE BLOWN AWAY https://www.youtube.com/watch?v=Be7o6BYVOzA.

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Presentation on theme: "It’s Unbe-lava-bly awesome VOLCANOES. PREPARE TO BE BLOWN AWAY https://www.youtube.com/watch?v=Be7o6BYVOzA."— Presentation transcript:

1 It’s Unbe-lava-bly awesome VOLCANOES

2 PREPARE TO BE BLOWN AWAY https://www.youtube.com/watch?v=Be7o6BYVOzA

3 A LAVA BIT OF VOCAB Magma : molten rock (usually contained in a magma chamber) Eruption: when anything is ejected from volcanic vent Lava : Magma once at the surface of the earth Pyroclastic debris: fragments created by volcanic explosions Vent : opening in earths surface through which a volcanic eruption takes place

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5 HOW DO VOLCANOES FORM? Magma rises through cracks or weaknesses in the Earth's crust. Pressure builds up inside the Earth. When this pressure is released, eg as a result of plate movement, magma explodes to the surface causing a volcanic eruption. The lava from the eruption cools to form new crust. Over time, after several eruptions, the rock builds up and a volcano forms.

6 HOW DO VOLCANOES FORM? At subducting boundaries, magma can get through the cracks of the two plates and make its way to the surface Volcanoes can also form by the magma simply working its way up to the surface It does this because it is less dense than the rock

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8 HOW DO VOLCANOES FORM? Let’s listen to the nice man tell us about volcanoes https://www.youtube.com/watch?v=jRfEGvp6wDU

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11 DO ALL VOLCANOES EXPLODE? Volcanoes can be active, dormant, or extinct An active volcano is one that has had an eruption in historical times (in the last few thousand years) A dormant volcano is one that has erupted in historical times and has the potential to erupt again, it just hasn’t erupted recently. An extinct volcano is one that scientists think probably won’t erupt again.

12 3 MAIN TYPES OF VOLCANOES

13 1. SHIELD VOLCANO Shield Volcano : broad and gentle sloping volcano Called shield based on the resemblance of an ancient Roman shield Very large in size Characterized by a low viscosity (resistance to flow) Doesn’t always erupt from the summit

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15 MOUNT ETNA http://www.forbes.com/sites/trevornace/2015/12/05/fire-lightning-mt-etna-erupts-sicily- ejecting-lava-air/ http://www.forbes.com/sites/trevornace/2015/12/05/fire-lightning-mt-etna-erupts-sicily- ejecting-lava-air/ https://www.youtube.com/watch?v=v0HULgTjaSA

16 WHY IS THERE LIGHTNING? Very mysterious Most volcanologists seem happy with the vague notion that ash particles thrown into the air rub against each other and generate enough static charge to trigger sparks

17 HAWAII SHIELD VOLCANOES The tallest volcano on Earth is Hawaii’s Mauna Kea, with an elevation of 4,207 meters. It’s only a little bigger than the largest volcano on Earth, Mauna Loa with an elevation of only 4,169 meters. Both are shield volcanoes that rise up from the bottom of the ocean. If you could measure Mauna Kea from the base of the ocean to its peak, you’d get a true height of 10,203 meters (and that’s bigger than Mount Everest). https://www.youtube.com/watch?v=66UdZWZgfWY

18 2. PYROCLASTIC CONES OR CINDER CONES Volcano made from pyroclasts (fragment of rock made by volcanic explosion) Very steep slopes (in contrast to Shield variety) Most ejected material is collected on slopes of volcano and bound by gravity (can only get so steep) Generally have short lives (very few eruptions) Generally very short (few higher than 500m) Very explosive, but chambers usually small)

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21 STRATO OR COMPOSITE VOLCANO More viscous than shield volcanoes Volcano made from alternating layers of pyroclasts and rock solidified from lava flows Slopes come in variety of steepness (a mix of shield and cinder) Lava flows fatten, while pyroclasts build up Built over long spans of time (long time between eruptions usually), so generally very large Usually the most destructive (pyroclastic flows, tephra, lots of ejected material)

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23 MT. ST. HELENS

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25 BILL NYE AND VOLCANOES https://www.youtube.com/watch?v=gOc04z8jHaM Crazy people near lava https://www.youtube.com/watch?v=VuQrUwFn6bU

26 VOLCANIC DESTRUCTION 1.Pyroclastic Flows 2.Lahars 3.Tephra

27 1. PYROCLASTIC FLOW Fast-moving current of extremely hot gas Travel away from a volcano at speeds generally as great as 700 km/h 1,000°C

28 PYROCLASTIC FLOW https://www.youtube.com/watch?v=Cvjwt9nnwXY

29 2. LAHARS Mudflow and debris flow composed of pyroclastic material, rocky debris, and water The material flows down from a volcano, typically along a river valley Where does the liquid come from? Burst dam Glacial, snow melt Can flow around 35 km/h https://www.youtube.com/watch?v=WEAfXO7q8Xs https://www.youtube.com/watch?v=jgWbYDUm-ME

30 3. TEPHRA Any broken piece of material that is produced from a volcanic explosion (Very similar to pyroclastic debris) Tephra have 3 main classifications: Ash – particles smaller than 2 mm in diameter, Ash Lapilli or volcanic cinders – between 2 and 64 mm in diameter, Lapilli Volcanic bombs or volcanic blocks – larger than 64 mm in diameter. Volcanic bombsvolcanic blocks

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33 SUPER VOLCANOES https://www.youtube.com/watch?v=G1pa6afh8o4&list=PL_JoINBzH43MiJhzOG8pOcRUd1 S-SoppB&index=21 https://www.youtube.com/watch?v=G1pa6afh8o4&list=PL_JoINBzH43MiJhzOG8pOcRUd1 S-SoppB&index=21


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