2006-08-29 00:40:06 · 7 answers · asked by Niranjan 3 in Science & Mathematics ➔ Earth Sciences & Geology
Volcanoes are "born" when magma (liquid rock inside the earth) reaches the surface. Depending on the type and duration of the eruption lava and or tephra can pile up to make a volcano. You might enjoy reading "Birth of Volcanoes" by Maurice Krafft (in Volcanoes Fire from the Earth: Abrams Discoveries, 208 p.).
Volcanoes erupt because of buoyancy and gas pressure. Buoyancy is a force that causes lighter material to rise through surrounding denser material (think of a hot air balloon rising in the cooler air). The hot liquid magma rises towards the surface through the more dense rock. Gas pressure from gas dissolved in the magma also exerts force on the surrounding rock. It cracks the rocks above the magma and then moves into the crack. This process repeats many times until the magma reaches the surface.
2006-08-29 00:55:52 · answer #1 · answered by Ashley/Angel 2 · 1⤊ 0⤋
Volcanoes are formed when the magma rises to the surface because of the subduction zones where two plates collide and the other one sinks and it will cause' a rise in the magma. thus producing a volcano.
2006-08-29 16:40:05 · answer #2 · answered by Mel Kesiah C 1 · 0⤊ 0⤋
When radioacitve elements (uranium, thorium and potassium) decay they heat up the Earth, causing the rock to melt and rise. When this molten rock breaks through to the surface of the Earth we call it a volcano.
2006-08-29 04:48:15 · answer #3 · answered by Amphibolite 7 · 0⤊ 1⤋
when the earth`s plates separate,and leave a crack in the earths surface.from this magma(which turns into lave after a while) comes up.the magma then cools and hardens,to form a volcano :)
2006-08-29 01:22:28 · answer #4 · answered by Anonymous · 0⤊ 0⤋
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2016-12-14 14:01:38 · answer #5 · answered by ? 4 · 0⤊ 0⤋
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2006-08-29 02:04:57 · answer #6 · answered by Tuan 2 · 0⤊ 1⤋
when pates collide under the earths surface and crack open
2006-08-29 00:50:53 · answer #7 · answered by asdsdfas2004 1 · 0⤊ 1⤋