Types of Volcanic Eruptions Explained

There are different types of volcanic eruptions, based on the physics and chemistry of the magma. Scientists classify these eruptions in various ways. Volcanoes can be split into two categories—effusive and explosive. Effusive eruptions flow along the ground. The lava is thin and fluid, and it does not have much gas trapped in it. Explosive eruptions blast lava, ash, and volcanic gases far into the air. They can also explode parts of the existing volcano, sending chunks of rock flying. This lava has a lot of gas trapped in it. The expanding gases cause the eruptions. Another classification system divides volcanoes into six categories, based on descriptions of how they erupt. Each category is named for a place in the world where that type of eruption has occurred. Icelandic eruptions are effusive. Molten lava flows smoothly from long fissures, or cracks, in the ground. Hawaiian eruptions are also effusive. Lava flows from the summit of a volcano and from cracks in the sides of the volcano. Strombolian eruptions are small explosive eruptions. These volcanoes erupt often in small bursts. Expanding gases throw clots of lava into the air. Vulcanian eruptions have moderate explosions of gas with volcanic ash. They form rapid eruption clouds. Pelean eruptions have large explosive outbursts. They produce pyroclastic flows—dense mixtures of volcanic fragments and gas that roll down slopes. Plinian eruptions are the most dramatic. These enormous explosive eruptions resemble a rocket blast. Gases and volcanic fragments are blown more than 18 miles (30 kilometers) in the air.