volcanoes and volcanism

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volcanoes and volcanism

  1. 1. Introduction to Volcanology May 2008 Chapter 1
  2. 2. Content <ul><li>1.- Volcano . </li></ul><ul><li>Concept. </li></ul><ul><li>Origin. </li></ul><ul><li>Parts. </li></ul><ul><li>Earthquakes, tsunamis and volcanoes. </li></ul><ul><li>Volcanology. </li></ul><ul><li>2.- Volcanism . </li></ul><ul><li> Concept. </li></ul><ul><li>Types. </li></ul><ul><li>Heat source. </li></ul><ul><li>Isotopes. </li></ul><ul><li> Accretional heating. </li></ul><ul><li>Tidal heating. </li></ul><ul><li> Core formation. </li></ul><ul><li>Meteorits. </li></ul>
  3. 3. VOLCANO
  4. 4. Volcano <ul><li>An opening in the earth’s surface through which lava, hot gases, and rock fragments erupt. </li></ul>
  5. 5. Origin of Volcanos <ul><ul><li>1.- Magma 50-100 miles below the earth’s surface slowly begins to rise to the surface. </li></ul></ul><ul><ul><li>2.- As the magma rises it melts gaps in the surrounding rock. </li></ul></ul><ul><ul><li>3.- As more magma rises a large reservoir forms as close as 2 miles below the surface (magma chamber) </li></ul></ul><ul><ul><li>4.- Pressure from the surrounding rock causes the magma to blast or melt a conduit (channel) to the surface where magma erupts onto the surface through a vent (opening). </li></ul></ul><ul><ul><li>5.- The magma, now called lava, builds up at the vent forming a volcano. </li></ul></ul><ul><ul><li>6.- Often the volcano sides will be higher than the vent forming a depression called a crater </li></ul></ul>
  6. 6. Volcano Mount Saint Helen Eruption, May 18th 1980
  7. 7. Magma chamber conduit mantle Parasitic Cone Ash Cloud/Gases Vent Lava Flow Crater Parts of a Volcano
  8. 8. “ Ring of Fire” Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the so-called , a zone of frequent earthquakes and volcanic eruptions.
  9. 9. Volcanoes and earthquakes <ul><li>The distribution of earthquakes provides information about magma pathways and the structure of volcanoes and they also can have a lot to do with generating tsunami. Any time that you can somehow displace a large amount of ocean water you generate a large wave or group of waves that goes rushing across the ocean at great speed. </li></ul>
  10. 10. Volcanology <ul><li>Volcanology (also spelled vulcanology) is the branch of geology that studies volcanoes, lava, magma and related geological phenomena. </li></ul>
  11. 11. VOLCANISM
  12. 12. Volcanism <ul><li>Volcanism is part of the process of bringing material from the deep interior of a planet and spilling it forth on the surface. In many cases, eruptions build up a </li></ul><ul><li> piled of material, a mountain what is called volcano. </li></ul>
  13. 13. Origin of Volcanism <ul><li>There are four types of volcanism: </li></ul><ul><li>- Related with midocean ridges. </li></ul><ul><li>- Related with subduction zones </li></ul><ul><li>- Related with Hotspots </li></ul><ul><li>- Related with flood volcanism </li></ul>
  14. 14. Heat Source <ul><li>The heat from a volcano comes from deep within the earth. Many miles underground, the earth is hot. Rocks beneath the earth are so hot they turn into a liquid called lava. </li></ul>When a volcano erupts, the steam and ash is caused by lava that is forcing its way toward the surface of the earth.
  15. 15. Isotopes <ul><li>Isotopes are any of the different forms of an element each having different atomic mass (mass number). Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. </li></ul>Therefore, isotopes have different mass numbers, which give the total number of nucleons—the number of protons plus neutrons. Hydrogen Deiterium Tritium
  16. 16. U 235 – U 238 <ul><li>U235 is an isotope of uranium that differs from the element's other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction, i.e., it is fissile. It is the only fissile isotope found in any economic quantity in nature. It was discovered in 1935 by Arthur Jeffrey. </li></ul>U238 is the most common isotope of uranium found in nature. In a nuclear reactor, it can be used to breed plutonium-239, which itself can be used in a nuclear weapon or as a reactor fuel source.
  17. 17. Th 232 – K 40 <ul><li>Thorium is found in small amounts in most rocks and soils. Th232 is used in combination with a fissile nuclide as a fuel source in types of nuclear reactors known as breeder reactors.  Breeder reactors are able to continually generate new fuel as fuel is being consumed.   </li></ul>K40 , which has a radioactive half-life of about 1.2 billion years, could be an important source of heat in the Earth’s core but this has never been unambiguously confirmed in an experiment.
  18. 18. Accretional Heating <ul><li>The heating of bodies orbiting a star due to bombardment by smaller objects . Accretional heating in forming planets results from the transfer of kinetic energy of objects striking the proto - planet surface. </li></ul>By accounting for all energy transfer for every cratering event it is theoretically possible to determine the thermal state of newly- formed planets
  19. 19. Tidal Heating In some other planents is too small to have left over accretional heat, and radioactive decay could not generate the tremendous energy required to power all of the volcanic activity that exists on the moon.
  20. 20. Core Formation <ul><li>Extensive melting of the earth as a result of giant impacts, accretion, or the presence of a dense blanketing atmosphere is thought to have led to the formation of the core. Collision between a planet- sized body and the earth may have also produced the moon. </li></ul>Near the end of accretion, core formation evidently ceased as upper mantle conditions became oxidizing. The accumulation of the oceans is a consequence of the change to oxidizing conditions.
  21. 21. Meteorits <ul><li>Chondrites are stony meteorites that have not been modified due to melting or differentiation of the parent body. They formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids </li></ul>

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