Melting
This video clip shows a lava flow coming from a volcano. It's temperature is about 1200oC.
Source: Stromboli Online
Source: Stromboli Online
Where are the volcanoes?
Map above reproduced courtesy of the Smithsonian Institution, Global Volcanism Program.See a larger map of the world with links to more information on some volcanoes around the world.
Find out more about how magma is formed.
Why is magma produced?
The map (on the left) shows where volcanoes occur. Here’s why:
Mid-ocean volcanoes
Where plates move apart, the hot rock of the Earth’s mantle layer gets closer to the surface and begins to melt, forming runny basalt magma.Ocean-edge volcanoes
Where plates come together, the ocean floor sinks down beneath the continent. As it gets hotter, water is released, which helps to melt the hot mantle rock, producing sticky andesite magma.Mountain belts
Sometimes continental rocks are also melted, producing. very sticky granite (or rhyolite) magma, but this rarely reaches the surface.