VOLCANOES Term 3 Flashcards Preview

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Flashcards in VOLCANOES Term 3 Deck (11):

What is a volcano?

A rupture in the crust of the Earth, allows hot lava, volcanic ash and gasses to escape from a magma chamber below the surface


Why do volcanoes occur?

Earth crust is broken into 17 tectonic plates that float on a hotter softer layer in the mantle


Name 4 hazards a volcano can cause

  1. volcanic ash threat to aircraft, ash particles damage the turbine
  2. large eruptions affect temp when ash obscures the sun and cools the Earth lower atmosphere or troposphere
  3. ash cloud absorb heat from Earth - warming the stratosphere
  4. Eruptions can cause volcanic winters which cause famines


Name the different types of volcanoes (6)


  1. Shield volcanoes
  2. Lava domes
  3. Volcanic cones/cinder cones
  4. Stratovolcanoes
  5. Super volcanoes


Explain shield volcanoes (7)LQ


  • broad, shield like profiles
  • Lawa flow great distance from vent
  • do not explode
  • more common in ocean than on continent
  • Hawaiian volcanic chain are shield volcanoes
  • also occur in Iceland


Explain Lava Domes (5)



  • formed by slow eruptions of lava
  • sometimes formed within crater of previous volcano
  • produce violent,explosive eruptions
  • Lava doesn't flow far from vent


Explain volcanic cones/cinder cones (5 )



  • Eruptions of small pieces of land that build up around vent
  • Short lived eruptions
  • Produce cone shaped hill
  • Cinder cones erupt only once * Form flank vents on larger volcanos


Explain Stratovolcanoes (8 )



  • tall mountains of lava flows
  • made of cinder, ash, lava
  • cinder and ash pile on each other lava flows over the cinder/ash where it cools and hardens, process is repeated
  • Ash of eruption is biggest threat to human
  • Preasure builds up from underlying lava, giving the most powerfull eruptions.
  • Steep slopes of 30 - 35*
  •  shoots loose material = volcanic bombs
  • big bombs measure 1.2 m across and weigh several tons


Explain Super Volcanoes (4)



  • Great defastation
  • Because of large area covered it cause cooling of global temp for many yrs
  • Sulphar and ash into atmosphere blocks sun
  • Most dangerous type of volcano


Name the 3 classifications of volcanos

and discuss each with 2-3 points


1.  Active:

* Lifespan is from months to several million yrs * Scientist consider a volcano active if it has erupted the past 10 000 yrs * Most active volcanos is Pacific Ring of Fire

2.  Extinct:

* Volcano cannot erupt because there is no more magma * If there is no written records of the activity it is considered extinct.

3.  Dormant:

* Difficult to seperate extinct and dormant. * Yellowstone has a dormant period of 700 000 yrs * Climate change can trigger volcano activity as well as changing pressure of ice or sea water * or extreme weather can trigger activity  


Discuss the Effects of Volcanoes (5)


1.  Volcanic Gasses: * Volcanoes Concentrations differ but * Water Vapour is the most common * followed by carbon & sulphur dioxide

2.  Acid Rain: * Gasses like carbon dioxide, hydrogen Chloride and hydrogen Fluride are released into atmosphere when volcano erupt * Gasses disolve in water droplets in eruption cloud * Fall back to ground in acid rain

3.  Advantages of volcanoes: * Put nutrients back into soil when volcano rocks  weather * is good for plants and crops * Can form new islands when magma cools and solidifies when in contact with water

4.  Volcanic Winters: * Took place 70 000 yrs ago in Indonesia. * Formed the Siberian Traps, most well known Volcanic area * Freezing winter in Europe in 1740 - 1741 led to wide spread famine

5.  Climate Change: * 1815 Mount Tambora erupted causing global climate change in Northern Hemisphere.   * Crops didn't grow and livestock died