How are volcanoes formed?
Most volcanoes occur where two plates meet. When two plates move apart causing a gap, hot molten rock – called lava – rises up between them. This type of volcano occurs on the ocean floor and is mostly invisible. If the amount of magma is large enough, it rises above the surface of the ocean and an island is created.If two plates collide and one plate is forced beneath the other plate, the friction makes the first melt and magma rises up. Only a few volcanoes on earth are formed like this, but their eruptions are the most violent and dangerous ones. Sometimes volcanoes also form in the middle of the plates which are called hotspots. These are places that are connected by channels to the hot mantle of the earth. Three main types of volcano are given below which are formed in distinct ways: – Shield volcano Shield volcanoes are almost completely basalt. When magma is very hot and flowing, gases can escape and eruptions are gentle with considerable amounts of magma reaching the surface to
You can imagine that the crust of the earth is like a very thin skin floating on a big ball of molten rock. Like a puzzle, it consists of different parts called tectonic plates that move very slowly. Most volcanoes occur where two plates meet: When two plates move apart causing a gap, hot molten rock – called lava – rises up between them. This type of volcano occurs on the ocean floor, so it is mostly invisible. Only if the amount of magma is big enough, it rises above the surface of the ocean and an island is created. A long time ago, Iceland was formed this way. If two plates collide and one plate is forced beneath the other plate, the friction causes the first to melt and magma rises up. Only a small part of the volcanoes on earth are formed like this, but their eruptions are the most violent and dangerous ones. Sometimes volcanoes also form in the middle of the plates, in so-called hotspots. These are places that are connected to the hot mantle of the earth by channels. The Hawaiia
Volcanoes are formed when magma from within the Earth’s upper mantle works its way to the surface. At the surface it erupts to form lava flows and ash deposits. Ash deposits result from more explosive activity and lava flows usually are associated with quieter activity. Anyway, once you have piled up lava and/or ash around the vent, you have a young volcano. After many many more eruptions you have a big volcano that is constructed of the ash and lava products of these eruptions.
