Volcanic Eruptions

Earth Science - Middle School

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Types of Eruptions There are two types of eruptions—quiet and explosive. Quiet eruptions are non-explosive and occur in volcanoes with low-viscosity, low-silica magma. The fast-moving lava flows out of the vent and across the surface of the land. Explosive eruptions occur in volcanoes with thick, high- viscosity magma that is high in silica. Magma builds up within the volcano's pipe rather than flowing out. Pressure increases until an explosive eruption occurs. magma lava ow vents Volcanic Material & Rocks Volcanic material can be found in all different sizes from tiny ash particles, to cinders, to large pieces called volcanic bombs. Pyroclastic Flow and Lahar Explosive eruptions release a mixture called a pyroclastic flow made up of hot ash, rocks and gases. A fast-moving mudflow called a lahar can also form during an explosive eruption. Obsidian, pumice, basalt, and rhyolite are all igneous rocks that form from volcanic eruptions. pyroclastic flow lahar obsidian pumice pumice magma reservoir lava vents lava flow cinders volcanic bombs basalt rhyolite Volcanic Eruptions © Copyright NewPath Learning. All Rights Reserved. 94-4537 Visit www.newpathlearning.com for Online Learning Resources. Photos courtesy of USGS & NOAA.
Pause and Review Identify and describe the two types of eruptions volcanoes may have. Volcanic Eruptions Type: _______________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Type: _______________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ © Copyright NewPath Learning. All Rights Reserved. 94-4537 Visit www.newpathlearning.com for Online Learning Resources.