* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Volcanic Eruption
Volcanic ash wikipedia , lookup
Llullaillaco wikipedia , lookup
Mount Garibaldi wikipedia , lookup
David A. Johnston wikipedia , lookup
Mount Pleasant Caldera wikipedia , lookup
Mount Meager massif wikipedia , lookup
Mount St. Helens wikipedia , lookup
Shield volcano wikipedia , lookup
Mount Pinatubo wikipedia , lookup
Mount Edziza volcanic complex wikipedia , lookup
Volcanology of Io wikipedia , lookup
Volcanology of Mars wikipedia , lookup
Cascade Volcanoes wikipedia , lookup
Nevado del Ruiz wikipedia , lookup
Mount Vesuvius wikipedia , lookup
Wells Gray-Clearwater volcanic field wikipedia , lookup
Types of volcanic eruptions wikipedia , lookup
Mount Pelée wikipedia , lookup
Earth Science Notes Volcanic Eruptions Our Objectives Today are… I can … • Explain the Factors that affect Volcanic Eruptions • Describe the Features of Volcanic Activity – Intrusive Igneous Rocks (CH 5) • Describe the destructiveness of Volcanoes • The Circle of Life Factors Affecting Eruptions Trapped Gases • Carbon dioxide and water vapor get trapped in magma and escape when pressure decreases • Gases that build up a lot of pressure cause explosive eruptions Factors Affecting Eruptions • Gases build up more pressure in thicker (more viscous) magma. • What type of magma would cause the greatest explosion. Recall: Unit 3 Viscosity means RESISTANCE TO FLOW Factors Affecting Eruptions Silica Content • Silica is a compound composed of silicon and oxygen • Magma that is silica-rich (i.e. Granitic) produces explosive eruptions – Has a high viscosity (THICK) – TRAPS more gasses – RECALL: silica-rich magma formed granitic (felsic) rocks Factors Affecting Eruptions Silica Content • Silica is a compound composed of silicon and oxygen • Magma that is silica-poor (i.e. Basaltic) produces quiet explosions – Has a LOW viscosity (Thin) – Forms nonexplosive eruptions – RECALL: silica-poor magma formed basaltic (mafic) rocks Hawaiian Volcano Basaltic Andesitic Granitic (Rhyolitic) Factors Affecting Eruptions • Low Viscosity (Basaltic) Magma – https://www.youtube.com/watch?v=qTTLYx4X o2k • Higher Viscosity (Granitic) Magma – https://www.youtube.com/watch?v=e4PUOBI wEv0 Volcanic Eruption Types • Volcanic eruptions are characterized by expolosivity and height of plume. Please Note: as with classification scheme, there are several forms and eruptions may be difficult to distinguish at times Volcanic Eruption Types Four Main categories of volcanic eruptions (see EN: Kinds of Eruptions) • Hawaiian – weakest • Strombolian – weak • Vulcanian – kind of explosive • Pelean – massive explosions Volcanic Eruption Types Hawaiian Eruptions https://www.youtube.com/watch?v=CSu_n etRm8E Volcanic Eruption Types Strombolian Eruptions https://www.youtube.com/watch?v=wS57sd7j9Y Volcanic Eruption Types Vulcanian Eruptions https://www.youtube.com/watc h?v=YF7ib5ToVs4 Volcanic Eruption Types • Pelean Eruptions Volcanic Eruption Types • Even Larger than a Pelean Eruption are Plinian Eruptions https://www.youtube.com/watch?v=IETUa_ nOk1g Volcanoes Destructiveness Mount Vesuvius - 79 AD Volcanoes Destructiveness • Mount St. Helen - Washington Volcanoes Destructiveness Features Of Volcanic Activity Limnic Eruptions: Lake Nyos Features Of Volcanic Activity Limnic Eruptions: Lake Nyos • Lake Nyos is a deep lake high on the flank of an inactive volcano in Cameroon. • A pocket of magma lies beneath the lake, charging the water with an estimated 90 million tonnes of carbon dioxide (CO2). • In 1986, a limnic eruption at Lake Nyos triggered the sudden release of about 1.6 million tonnes of CO2 that rushed down nearby valleys, displacing all the air and suffocating approximately 1,700 people within 20 km of the lake. Features Of Volcanic Activity Limnic Eruptions: Lake Nyos Elements for a Limnic Eruption • Very deep volcanic lake. • Lake has to be over a slow source of volcanic gas. • Lake has to be very, very still. Features Of Volcanic Activity Limnic Eruptions: Lake Nyos Volcanoes Destructiveness Volcanoes Destructiveness This Diagram shows range of potential destruction A super-eruption has the potential to cover the United States in 3 feet of ash from a plume. Pyroclastic flow would engulf the greater part of three states, and there is evidence that the last major 'super' eruption plunged the world into a freezing, volcanic winter that lasted a decade. An eruption would devastate world agriculture, severely effect the distribution of food and cause mass famine. After the Aftermath Features Of Volcanic Activity • Batholiths – formed when magma cools underground Features Of Volcanic Activity • Volcanic Neck – magma inside volcano cools and outside is eroded away Features Of Volcanic Activity • Dike – magma that cools in vertical cracks Features Of Volcanic Activity • Sill – magma that cools in horizontal cracks Features Of Volcanic Activity • Caldera – top of volcano collapses on emptied magma chamber Photograph by M. Williams, National Park Service, 1977 Features Of Volcanic Activity Features Of Volcanic Activity Our Objectives Today were… Can I … • Explain the Factors that affect Volcanic Eruptions • Describe the Features of Volcanic Activity – Intrusive Igneous Rocks (CH 5) • Describe the destructiveness of Volcanoes • The Circle of Life