Transcript Volcanoes
Volcanoes Chapter 8 Section 2 Pgs. 219 - 224 How volcanoes form Fissure – crack in the crust, where a conduit forms which acts like a pipe magma travels through Magma is forced upward toward Earth’s surface by denser surrounding rock Causes an eruption where magma, solids, and gas are spewed out to form cone-shaped mountains Lava – magma flowing on Earth’s surface through a vent or opening Craters – circular hole of volcano Tephra – bits of rock or solidified lava dropping from the air Reservoir – where magma is stored Summit – highest point Vent - opening where lava flows Where Plates Collide Volcanoes form by a collision of large plates of crust and upper mantle Oceanic plate sinks under another plate, rocks melt, forms chambers of magma Volcanic Risk Maps Used to prepare people and visitors about unsafe areas Volcanic Eruptions Violent or quiet Lava high in silica produces explosive eruptions Lava high in iron and magnesium produces more fluid eruptions The amount of water vapor and gases impact eruptions Shield Volcanoes Largest type of volcano Gently sloping volcano that emits mostly basaltic lava (very fluid) that is long-lasting, gentle eruptions, explosions minimal Mauna Loa, HI Made from 5 shield cones Largest volcano on Earth – Mauna Loa in Hawaii, 6 miles tall Cinder Cone Volcanoes Smallest volcano, very steep with large craters Formed by moderate to explosive eruptions of tephra Cinder Cone Volcano Pu ‘ u ka Pele – Hawaii Mostly found on the sides of shield volcanoes Composite Volcano Steep sides Formed by alternating layers of violent eruptions of tephra and quieter eruptions of lava Composite Volcano Most active volcano – Mt. St. Helens in the western part of the state of Washington Extreme Volcanoes Largest volcano in the Solar System – Olympus Mons on Mars, 17 miles tall and over 320 miles across. Questions Hawaii is an example of what type of volcano? What are the three types of material that a volcano can emit? The eruption of Mount Vesuvius buried what town in 79 A.D.? How did people die in the aftermath of the famous Mount Vesuvius eruption? Mount St. Helen’s erupted violently in 1980. On what continent is this volcano found?