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Magma & lava - Coggle Diagram
Magma & lava
Lava
Lava is a solution of silicate minerals. It is similar to the hot liquid that would result if granite or basalt were melted.
When lava first comes to the surface it is red–hot, reaching temperatures from 7 to 12 times hotter than boiling water (212° F).
Types of lava
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Pahoehoe is so fluid that when it first erupts, it flows down the side of a volcano faster than a person can run.
Both kinds cool at the surface first, forming a solid crust over a liquid core.
When lava cools rapidly, only a few crystals can form. The lava hardens into a rock that contains large amounts of natural gas.
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From time to time, they blow out quantities of dust and rock fragments that form layers between lava flows.
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As the gases expand, they are trapped in the lava and form many bubbles.
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Pyroclastics
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The size of pyroclastic material ranges from boulders the size of houses to tiny particles that can remain suspended in the atmosphere for years.
Falling ash can contaminate water supplies, damage crops, and collect in great masses on roofs, causing them to collapse.
Falling ash also blocks sunlight and reduces visibility, complicating evacuations. Ash can clog the engines of jet aircraft and parts of other machines, causing them to fail.
Dispersed ash can remain in the stratosphere for years, where it can cool the atmosphere by blocking some sunlight.
The most dangerous volcanic hazards are pyroclastic flows and surges, clouds of hot ash and gas that travel mostly along the ground.
They can choke or poison people with gases, bury people with debris, and burn them with temperatures of up to 1100º F.
They advance tens or hundreds of feet per second and can even cross such natural barriers as rivers and ridges. People and animals cannot outrun pyroclastic flows and surges.
Magma
Basaltic
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It is extremely fluid and may flow long distances from its eruption site. It’s usually associated with quiet, nonexplosive eruptions.
This type of lava pours from volcanic vents and runs down the sides of a volcano. When basalt erupts underwater, it forms rounded pillow–shaped lumps called pillow lava.
When it erupts on land, its surface has either a smooth, rope-like texture, or a jagged angular one.
Granitic
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Silica–rich, or granitic, magma produces explosive eruptions.
Granitic magma is thick, and gases get trapped inside, causing pressure to build up.
When an explosive eruption occurs the gasses expand rapidly, often carrying pieces of lava in the explosion.
Andesitic
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Because of its higher silica content, it also erupts more violently than basaltic magma.
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Volcanic activity
When intrusive volcanic activity occurs, magma moves into the earth's crust but not onto the earth's surface.
Extrusive volcanic activity brings lava, pyroclastics, and gases to the Earth’s surface.