Volcanoes Timothy McAuliffe
Main Facts <ul><li>Volcanoes form when magma reaches a weak spot on the surface of the Earth and breaks through </li></ul>...
Ring of Fire <ul><li>The Ring of Fire is located along the outer edge of the Pacific Plate, and this is the location of ma...
Process <ul><li>This image shows a stratovolcano </li></ul><ul><li>Very straight, tall volcano formed by compounded layers...
Types of Volcanoes <ul><li>Shield Volcano </li></ul><ul><ul><li>Broad, though shallow </li></ul></ul><ul><ul><li>Arises be...
Types of Volcanoes <ul><li>Fissure Volcano </li></ul><ul><ul><li>Crack in the Earth at a convergent boundary </li></ul></u...
Types of Volcanoes <ul><li>Complex Volcano </li></ul><ul><ul><li>Referring to the system of the volcano not simple </li></...
Volcano Features <ul><li>Calderas and Crater Lakes </li></ul><ul><ul><li>Huge bowl shaped craters, mostly created by volca...
Volcanic Features <ul><li>Lava Plateaus </li></ul><ul><ul><li>This formation occurs when lava flows rapidly onto a small p...
Types of Volcanic Eruptions <ul><li>Strombolian </li></ul><ul><ul><li>Occurs when magma is viscous and locked up gases esc...
Types of Volcanic Eruptions <ul><li>Peléan or Nuée Ardente </li></ul><ul><ul><li>Large amounts of ash, dust, gases, and la...
Types of Volcanic Eruptions <ul><li>Plinian </li></ul><ul><ul><li>Most powerful and have the most explosive, unexpected er...
Hazards of Volcanoes <ul><li>Pyroclastic Flows </li></ul><ul><ul><li>Mixtures of gases, ash, and volcanic rocks falling at...
Hazards of Volcanoes <ul><li>Lahars </li></ul><ul><ul><li>Mudslides caused by a mixture of volcanic material and water </l...
Hazards of Volcanoes <ul><li>Avalanches </li></ul><ul><ul><li>Avalanches are caused when volcanic rock comes loose and rap...
Advantages of Volcanoes <ul><li>Resources </li></ul><ul><ul><li>Geothermal Resources </li></ul></ul><ul><ul><ul><ul><li>En...
Predicting Volcanoes <ul><li>The main ways to observe and predict eruptions are: </li></ul><ul><ul><li>Seismographic Monit...
Predicting Volcanoes <ul><li>Surveillance by Satellite </li></ul><ul><ul><li>This system uses Global-Positioning System to...
Sources <ul><li>Information: </li></ul><ul><ul><li>http://www.pbs.org/wnet/savageearth/volcanoes/index.html </li></ul></ul...
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1.4 Volcanoes Tim

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1.4 Volcanoes Tim

  1. 1. Volcanoes Timothy McAuliffe
  2. 2. Main Facts <ul><li>Volcanoes form when magma reaches a weak spot on the surface of the Earth and breaks through </li></ul><ul><li>Most of the more than six-hundred volcanoes are located on plate boundaries </li></ul><ul><li>Usually occur in subduction zones, when a plate slides beneath another </li></ul><ul><li>As plate sinks magma collects and builds up in magma chambers and when it finds a weak patch and the pressure is high enough it will erupt </li></ul>
  3. 3. Ring of Fire <ul><li>The Ring of Fire is located along the outer edge of the Pacific Plate, and this is the location of many convergent boundaries </li></ul><ul><li>Three-fourths of all of the Earth’s active and dormant volcanoes lie on this plate boundary </li></ul><ul><li>Volcanoes that form along the Ring of Fire usually form because of the highly viscous lava, pressured with large amounts of gases, erupts violently onto the Earth’s surface </li></ul>Nazca Plate lowers below the South American Plate Pacific Northwest Juan de Fuca plate is lowering beneath the North American Plate Pacific Plate dips beneath the Eurasian Plate Indo-Australian Plate lowers below the Pacific Plate Pacific Plate lowers below Indo-Australian Plate
  4. 4. Process <ul><li>This image shows a stratovolcano </li></ul><ul><li>Very straight, tall volcano formed by compounded layers of ash </li></ul><ul><li>Now hot magma is rising higher towards the dome of the volcano and when highly pressured gases are released the volcano will eventually erupt </li></ul><ul><li>When the pressured gases eventually are released they rupture with so much force that magma erupts as well </li></ul><ul><li>Because of its brute force rocks, debris, and magma upward into the air </li></ul><ul><li>Because of the varying sizes of rocks and debris, some of these items move swiftly along the sides of the volcano downward </li></ul><ul><li>This flowing down the sides of volcanoes is commonly known as pyroclastic flows. </li></ul>Animations from http://www.pbs.org/wnet/savageearth/animations/volcanoes/index.html
  5. 5. Types of Volcanoes <ul><li>Shield Volcano </li></ul><ul><ul><li>Broad, though shallow </li></ul></ul><ul><ul><li>Arises because of running lava </li></ul></ul><ul><li>Dome Volcano </li></ul><ul><ul><li>Steep, convex shape </li></ul></ul><ul><ul><li>Thick, fast-cooling lava </li></ul></ul><ul><li>Caldera Volcano </li></ul><ul><ul><li>Old Volcano </li></ul></ul><ul><ul><li>Large Crater opening, miles wide </li></ul></ul><ul><ul><li>Many new craters form inside the smaller one </li></ul></ul>
  6. 6. Types of Volcanoes <ul><li>Fissure Volcano </li></ul><ul><ul><li>Crack in the Earth at a convergent boundary </li></ul></ul><ul><ul><li>Also known as a mid-ocean ridge </li></ul></ul><ul><li>Ash-cinder volcano </li></ul><ul><ul><li>Besides lava, mainly spurts out ash </li></ul></ul><ul><ul><li>Volcano is mainly built up by ash and cinder </li></ul></ul><ul><li>Composite Volcano </li></ul><ul><ul><li>Built up by layers of lava and ash around the main crater </li></ul></ul><ul><ul><li>There are other smaller craters on its edge </li></ul></ul>
  7. 7. Types of Volcanoes <ul><li>Complex Volcano </li></ul><ul><ul><li>Referring to the system of the volcano not simple </li></ul></ul><ul><ul><li>Caldera complex volcanoes have a large crater with many subsidiary vents and deposits </li></ul></ul><ul><ul><li>Volcano with two or more vents is known as being compound or complex </li></ul></ul><ul><li>Spatter Volcano </li></ul><ul><ul><li>These are volcanoes where when hot lava is erupting there are enough explosive gases to prevent large amounts of lava flow </li></ul></ul><ul><ul><li>Instead they form fragments which are expelled and them fall to the volcano and accumulate on the vent </li></ul></ul>
  8. 8. Volcano Features <ul><li>Calderas and Crater Lakes </li></ul><ul><ul><li>Huge bowl shaped craters, mostly created by volcanic activity </li></ul></ul><ul><ul><li>Formed by violent eruptions and pyro-clastic material left on the unsupported surface of the volcano </li></ul></ul><ul><ul><li>Crater lakes are formed when these calderas formed when water fills inside of them </li></ul></ul>Caldera of Tengger in Java, Indonesia Crater Lake, Oregon <ul><li>Volcanic Plugs </li></ul><ul><ul><li>When lava solidifies on the pipe of a dormant volcano, eventually forming a plug </li></ul></ul>The Devil's Tower, Wyoming, USA
  9. 9. Volcanic Features <ul><li>Lava Plateaus </li></ul><ul><ul><li>This formation occurs when lava flows rapidly onto a small path and hardens </li></ul></ul><ul><ul><li>When this process occurs again and again it builds up the land forming a plateau </li></ul></ul>Columbia Plateau, USA <ul><li>Geysers </li></ul><ul><ul><li>Geysers are natural fountains, in which at regular intervals water and steam, are shot into the air </li></ul></ul><ul><ul><li>Occurs when water seeps through cracks in the Earth, so deep that it boils and in shot into the air, by the pressure </li></ul></ul>Yellowstone Geyser, USA
  10. 10. Types of Volcanic Eruptions <ul><li>Strombolian </li></ul><ul><ul><li>Occurs when magma is viscous and locked up gases escape when reaching the surface </li></ul></ul><ul><ul><li>Large amounts of magma and molten lava erupt in large arches </li></ul></ul><ul><li>Vulcanian </li></ul><ul><ul><li>A volcano in which a large ash cloud and gases form around the vent and rises up into the atmosphere </li></ul></ul><ul><ul><li>Cause violent explosions from recently dormant volcanoes </li></ul></ul>Parícutin Volcano, Mexico, 1947 <ul><li>Vesuvian </li></ul><ul><ul><li>Large amounts of ash are expelled violently and form a large cloud over the vent </li></ul></ul>Mount Vesuvius Volcano, Italy, 1944 Irazú Volcano, Costa Rica, 1965
  11. 11. Types of Volcanic Eruptions <ul><li>Peléan or Nuée Ardente </li></ul><ul><ul><li>Large amounts of ash, dust, gases, and lava fragments erupt and roll down the hill in a glowing avalanche </li></ul></ul><ul><li>Phreatic </li></ul><ul><ul><li>Result of expanding steam, when cold or surface water meets hot magma </li></ul></ul><ul><ul><li>Only blasts rock fragments </li></ul></ul>  Taal Volcano, Philippines, 1965 Phreatomagmatic Eruption Surtseyan Eruption <ul><li>Hydrovolcanic </li></ul><ul><ul><li>These are eruptions that are associated with water </li></ul></ul><ul><ul><li>Surtseyan Eruptions occur on shallow water, given low pressure </li></ul></ul><ul><ul><li>Phreatomagmatic Eruptions are when steam is violently erupted </li></ul></ul>
  12. 12. Types of Volcanic Eruptions <ul><li>Plinian </li></ul><ul><ul><li>Most powerful and have the most explosive, unexpected eruptions of mainly viscous lava and magma </li></ul></ul><ul><ul><li>There are large ash clouds and usually very fast-moving pyro-clastic flows </li></ul></ul><ul><li>Hawaiian, Hot Spots </li></ul><ul><ul><li>When this eruption occurs along a fissure or a fracture molten lava spurts upward and forms streams </li></ul></ul><ul><ul><li>Central-vent eruption has high towers of lava </li></ul></ul>Mount St. Helens, May 18, 1980 <ul><li>Submarine </li></ul><ul><ul><li>Occur under the ocean at mid-ocean ridges </li></ul></ul><ul><ul><li>Most of these eruptions go unnoticed because the ocean muffles the eruption </li></ul></ul>Mauna Loa Volcano, Hawaii, 1950   Kilauea Volcano, Hawaii, 1959
  13. 13. Hazards of Volcanoes <ul><li>Pyroclastic Flows </li></ul><ul><ul><li>Mixtures of gases, ash, and volcanic rocks falling at dangerous speeds down the side of the volcano </li></ul></ul><ul><ul><li>Ignimbrites </li></ul></ul><ul><ul><ul><li>Contains light material </li></ul></ul></ul><ul><ul><li>Nuées ardentes </li></ul></ul><ul><ul><ul><li>Has denser material </li></ul></ul></ul><ul><ul><li>Pyroclastic surges are low density pyroclastic flows which are more wide-spread, are much more dangerous, and contain toxic gases </li></ul></ul><ul><li>Gases </li></ul><ul><ul><li>Many gases from a volcano, especially large amounts of carbon dioxide can be very toxic to people </li></ul></ul>
  14. 14. Hazards of Volcanoes <ul><li>Lahars </li></ul><ul><ul><li>Mudslides caused by a mixture of volcanic material and water </li></ul></ul><ul><ul><li>Lahars can easily destroy property and kill people because of the strong cement-like stream </li></ul></ul><ul><li>Volcanic Ash </li></ul><ul><ul><li>Volcanic rock or stone that is expelled during an eruption measuring less than 2 millimeters in size </li></ul></ul><ul><ul><li>Dangers </li></ul></ul><ul><ul><ul><li>Small sharp, glass-like particles that damage most things they touch </li></ul></ul></ul><ul><ul><ul><li>During rains, because of the ash they can suffocate humans and animals </li></ul></ul></ul><ul><li>Lavaflow </li></ul><ul><ul><li>Most damage by lava is often caused by the harsh fires they set off </li></ul></ul>
  15. 15. Hazards of Volcanoes <ul><li>Avalanches </li></ul><ul><ul><li>Avalanches are caused when volcanic rock comes loose and rapidly slopes down the side of a steep volcano </li></ul></ul><ul><ul><li>A landslide is when gravity pulls material down the slope gradually </li></ul></ul><ul><ul><li>Effects </li></ul></ul><ul><ul><ul><li>Main effect is tsunamis, which are large groups of continuous waves </li></ul></ul></ul><ul><ul><ul><li>Debris can also mix with water forming deadly lahars </li></ul></ul></ul><ul><li>Volcanic Blast </li></ul><ul><ul><li>Blasts occur when large amounts of magma come out of the volcano on one side, this causes a lot of pressure on one side causing the vent to partially collapse </li></ul></ul><ul><ul><li>Then at the release of pressure the lava is forced upward into the air </li></ul></ul>
  16. 16. Advantages of Volcanoes <ul><li>Resources </li></ul><ul><ul><li>Geothermal Resources </li></ul></ul><ul><ul><ul><ul><li>Energy from the heat of the volcano is transferred into energy </li></ul></ul></ul></ul><ul><ul><ul><ul><li>This form of energy is very clean and does not exhaust fumes </li></ul></ul></ul></ul><ul><ul><li>Fertile Land </li></ul></ul><ul><ul><ul><li>After ash is expelled, it decomposes into the soil and forms fertile land with useful minerals </li></ul></ul></ul><ul><li>Landscape and Tourism </li></ul><ul><ul><li>Volcanoes cause wonderful scenery and landscapes </li></ul></ul><ul><ul><li>Volcanoes also cause large amounts of tourism </li></ul></ul>
  17. 17. Predicting Volcanoes <ul><li>The main ways to observe and predict eruptions are: </li></ul><ul><ul><li>Seismographic Monitoring </li></ul></ul><ul><ul><ul><li>Rising magma causes small earthquake tremors </li></ul></ul></ul><ul><ul><ul><li>As the magma approaches to erupting the magnitude and amount of tremors will increase </li></ul></ul></ul><ul><ul><li>Tiltmeters </li></ul></ul><ul><ul><ul><li>This is a measuring tool consisting of three pots in a triangle filled with water or mercury </li></ul></ul></ul><ul><ul><ul><li>These measurement tools are affected because of land deformation </li></ul></ul></ul>
  18. 18. Predicting Volcanoes <ul><li>Surveillance by Satellite </li></ul><ul><ul><li>This system uses Global-Positioning System to watch ground deformation and predict future eruptions </li></ul></ul><ul><li>Gas and Steam Emissions </li></ul><ul><ul><li>As these emissions increase, it shows that the magma is rising closer to the surface </li></ul></ul><ul><ul><li>This information is usually notice when equipment is damaged by the gases or people notice their noxious fumes </li></ul></ul>
  19. 19. Sources <ul><li>Information: </li></ul><ul><ul><li>http://www.pbs.org/wnet/savageearth/volcanoes/index.html </li></ul></ul><ul><ul><li>http://www.pbs.org/wnet/savageearth/hellscrust/html/sidebar3.html </li></ul></ul><ul><ul><li>http://www.mediatheek.thinkquest.nl/~ll125/en/volcano.htm </li></ul></ul><ul><ul><li>http://pubs.usgs.gov/gip/volc/types.html </li></ul></ul><ul><ul><li>http://library.thinkquest.org/17457/volcanoes/index.php </li></ul></ul>

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