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A volcano is a weak spot in the earth's crust and is filled with magma. Magma is a substance from the mantle of the earth's crust which is made of water vapor,gases,and rock. Once magma reaches the surface it is now called lava. Once lave has harden solid rock that makes the earth's surface. After volcanic activity it makes new rocks and after time it will make new islands. The is around 600 active volcanoes that could erupt. Lots of volcanoes are still beneath the sea. A major volcano belt is The Ring of Fire,which is formed by the many volcanoes on the edge of the pacific ocean. There are volcanic belts along the boundaries of Earth's plates. At the plate boundaries,very big pieces of lithosphere diverge or converge. Here when the lithosphere diverge or converge it allows the magma be able to go and reach the surface. Usually all volcanoes occur on,along and around diverging plate boundaries. But not all volcanoes are,some are formed at hot spots. Along the mid-ocean ridge volcanoes are formed which marks a diverging plate boundary. Lava pours out of cracks in the ocean floor along the ridge. Only in very few places,such as Azores Islands and Iceland in the Atlantic ocean,volcanoes of the mid-ridge rise above the surface of the ocean. Lots of volcanos form around plate boundaries where some oceanic crust returns to the mantle. Subduction makes pieces of ocean crust fall through a deep ocean trench which then goes to the mantle. After that the crust will melt and creates magma which will rise back up to the surface. Once the crust melts and makes magma and rises and then erupts which then the magma is lava it makes a new volcano.
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