Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, | The concentrations of different can vary considerably from one volcano to the next |
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This is a reference aimed at geologists, but many articles are accessible to non-professionals | Volcanic eruptions may inject into the |
These "" volcanoes generally only occur above e | All of these activities can pose a hazard to humans |
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They are the most dangerous type of volcano | Ultramafic flows, also known as , are very rare; indeed, very few have been erupted at the Earth's surface since the , when the planet's heat flow was higher |