Volcanic Eruptions by Dünya
By Dünya, Year 6
A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. Sixty percent of all active volcanoes occur at the boundaries between tectonic plates. Most volcanoes are found along a belt, called the “Ring of Fire” that encircles the Pacific Ocean. Some volcanoes, like those that form the Hawaiian Islands, occur in the interior of plates at areas called “hot spots.
Volcanoes are created over approximately 10,000-500,000 years by thousands of eruptions. This is because volcanoes erupt the hot lava and as it flows it begins to cool down and dry up, leaving a blacky brown rock like layer of lava. And as the years go by it begins to build up and create a mountain.
Lava is mostly made of two elements — Si (the symbol for silicon) and O (the symbol for oxygen). Together, they make a very strong bond and then get together with other elements, like Fe (iron), Mg (magnesium), K (potassium), Ca (calcium), and more. Molten rock, known as magma, erupts through fissures in Earth’s crust, becoming lava. The orange-red color allows us to determine the temperature of the lava, which is hottest at the tip of the cinder cone and less hot as we view the lava flows farther down.
Volcanoes erupt when molten rock called magma rises to the surface. Runny magma erupts through openings or vents in the earth’s crust before flowing onto its surface as lava. If magma is thick, gas bubbles cannot easily escape and pressure builds up as the magma rises. Magma is formed when the earth’s mantle melts. Melting may happen where tectonic plates are pulling apart or where one plate is pushed down under another. Magma is lighter than rock so it can rise towards the Earth’s surface.
Volcanic eruptions of this magnitude can impact global climate, reducing the amount of solar radiation reaching the Earth’s surface, lowering temperatures, and changing atmospheric circulation patterns. Atmospheric circulation transports heat and water above the Earth’s surface. Changes in temperature of air masses due to atmospheric circulation can cause water to change between a gas, liquid, and solid.
Did you know that more than 80% of the earth’s surface is volcanic in origin and the sea floor and some mountains were formed by countless volcanic eruptions. Gaseous emissions from volcanoes formed the earth’s atmosphere and there are more than 500 active volcanoes in the world.
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