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Volcanoes

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by

Omar Asousy

on 6 January 2014

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Transcript of Volcanoes

Volcanoes
How volcanoes are formed
A volcano is formed when high temperature and pressure causes rock to melt into magma. When magma forms it rises through the denser rock layers towards the earth's surface. When it reaches the surface it is called lava. A mountain or hill that is formed when lava rises through the earth's crust.
Inside a volcano
Silica
Silica
is the material in magma that creates the color. Magma with more silica is lighter the magma with less. Magma with less silica is more flowing because silica creates higher
viscosity
in magma which means the fluid is resists flowing.
Obsidian and pumice
Obsidian is a type of natural glass which is formed by heat and pressure. It contains a lot of silica. It is formed when rhyolitic lava is cooled quickly. Indians made knives, arrowheads, and ornaments from this rock. Pumice is another type of rock that has a lot of silica. Pumice is so light that it actually floats in the water and fragments might be washed ashore far from the volcano.
What happens when a volcano erupts?
Volcanic eruptions start with dissolved gases trapped in magma are under tremendous pressure. The pressure decrease when a magma rise toward to the surface. The dissolve gases begin to separate out forming bubbles. The volcano erupt on the rock on the surface that are weak. During a volcanic eruption, the gases dissolved in magma rush out, carrying the magma with them.
basalt
rhyolite
Magma chamber - the pocket beneath a volcano where magma collects
Pipe - a long tube where magma moves from the magma chamber to the surface
Vent - the opening through which molten rock and gas leave a volcano
Lava flow - the area covered by lava as it pours out of a volcano's vent
Crater - a bowl shaped area that forms around a volcano central opening
Silica - a material that is formed from the elements oxygen and silicon; silica is found in magma
Viscosity - the state of being thick and sticky; Viscosity increases with increasing silica content
Q1: What are the stages that lead up to a volcanic eruption?
A1: During a volcanic eruption the gases dissolve and magma rushes out, carrying the magma with them.

Q2: What does it look like inside a volcano?
A2: Beneath a volcano magma is collected in a magma chamber. It goes through a pipe and through a land tube. Finally, it goes out through vent or side vent.

Q3: What are the characteristics of magma?
A3: It partly depends on the amount of gas dissolved in the magma. Silica, which is formed by the elements oxygen and silicon, make the color of the magma.
Fun facts
Pacific Ring of Fire


Credits
Omar - Presentation, How a Volcano is Formed, Silica
Ishmael - Written Q&A, Inside a Volcano, Obsidian and pumice
Thomas - Research Vocab, Present Vocab, Ring of Fire
Mengting - Written Notes, What Happens When a Volcano Erupts
Kahli - Research Vocab, Present Q&A
Yaloon - Research, Fun Facts
Inside a volcano there is a
magma chamber
. In there magma collects before it goes through a
pipe
. Once in the pipe it may either go through a
vent
or side vent. If it went through a vent I usually goes through a
crater
. If it went through a side vent usually it would come out of a parasitic cone. Finally, a
lava flow
is created and an ash cloud rushes out the volcano and into the air.
Silica content Rock
50% Basalt
60% Andesite
65% Dacite
70% Rhyolite
The word volcano originally comes from the name of the Roman god of fire, Vulcan.
The Pacific Ring of Fire is where over 75% of the volcanoes on Earth are found.
There are also volcanoes found on the ocean floor and even under icecaps, such as those found in Iceland.
The Ring of Fire is the result of plate tectonics. The edges of several tectonic plates meet along the Ring of Fire, resulting in a convergent boundary, a divergent boundary, or a transform boundary. The Ring of Fire is the home of most of the active volcanoes on Earth, most of them located on the rings eastern edge. Mount Ruapehu in New Zealand is one of the more active volcanoes in the Ring of Fire, with yearly minor eruptions and major eruptions occurring about every 50 years.
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