* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Section 6.1 Volcanic eruptions
Mono–Inyo Craters wikipedia , lookup
Large igneous province wikipedia , lookup
Axial Seamount wikipedia , lookup
Itcha Range wikipedia , lookup
Mount Garibaldi wikipedia , lookup
Mount Meager massif wikipedia , lookup
Llullaillaco wikipedia , lookup
Craters of the Moon National Monument and Preserve wikipedia , lookup
Level Mountain wikipedia , lookup
Mount Pinatubo wikipedia , lookup
Mount Pleasant Caldera wikipedia , lookup
Cascade Volcanoes wikipedia , lookup
Olympus Mons wikipedia , lookup
Shield volcano wikipedia , lookup
Cerro Blanco (volcano) wikipedia , lookup
Mount Edziza volcanic complex wikipedia , lookup
Lascar (volcano) wikipedia , lookup
Mount St. Helens wikipedia , lookup
Wells Gray-Clearwater volcanic field wikipedia , lookup
Volcanology of Io wikipedia , lookup
Nevado del Ruiz wikipedia , lookup
Silverthrone Caldera wikipedia , lookup
Cerro Azul (Chile volcano) wikipedia , lookup
Mount Vesuvius wikipedia , lookup
Volcanoes Areas of Earth’s surface through which magma & volcanic gas passes Creative Forces forming fertile farmland & large mountains Destructive Forces Turning mountains into clouds of ash & rock, destroying forests & homes Structure of a typical volcano. Notice the alternating layers of ash and hardened lava. Why does this occur? Inside a Volcano Magma Body of molten rock (underground) that feeds a volcano Vents Opening through which volcanic material passes Nonexplosive Eruptions Most common type of eruption Release large amounts of lava Calm lava flow Pacific NW of USA covered from these eruptions Explosive Eruptions Rare & incredibly destructive Debris/molten rock blown out of volcano Large debris falls close to volcano Smaller, dust-sized particles (ash) can travel miles Magma Molten rock Composition affects how explosive a volcano is Silica (SiO2), Water, Gases (CO2, water vapor) When pressure decreases as magma rises, the CO2 and water vapor expand rapidly Silica Rich (Felsic) Magma Traps Gases Thicker, viscous Difficult for gases to escape, so pressure builds up What Erupts from a Volcano? Explosive Volcano Mainly pyroclastic material Magma that is blasted into the air and hardens Nonexplosive Volcano Mainly lava Eruptions can (and do) alternate between lava & pyroclastic eruptions (even within the same eruption) Types of Lava Aa jagged surface; brittle crust is torn by lave flow underneath Pahoehoe flows slowly; glassy surface has rounded wrinkles Pillow Lava rounded lumps formed under water B locky Lava does not travel far; heaps of sharp-edged chunks Types of Pyroclastic Material Formed when magma explodes and solidifies in the air Volcanic Bombs Large blobs that cool & harden in the air Lapilli Smaller, pebble-like stones that harden before hitting the ground Volcanic Ash Most of the material in an eruption Walls of gas bubbles explode into tiny, glass-like slivers Pyroclastic Flows Produced when enormous amounts of hot ash, dust, and gases are ejected from a volcano Speeds up to 200 km/h Temperatures over 700 C Review What factors influence whether a volcano erupts explosively? Review 2) How is lava classified? How are pyroclastic materials classified? 3) Explain how the presence of silica (felsic) and water in magma increases the chances of an explosive eruption. Answers 1) Pressure of gases, viscosity of magma, silica content, water, gases 2) Lava is classified by its surface texture; the way it flows may also be used to help classify lava. Pyroclastic material is classified by its size and how it forms. 3) As the magma moves towards the surface, the water changes to water vapor and expands rapidly; silica rich (felsic) magma is viscous and tends to trap volcanic gases and plug vents, the results in high pressures forming