Volcanic Activity

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Volcanic Activity
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How Magma Reaches the Surface

• Magma rises because magma is less __________ than
  the surrounding _________ material.
• It will rise until it reaches the ___________ or
  becomes trapped beneath _________ of _________.

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A Volcano Erupts

• A volcano erupts when an opening develops in
  _________ _________ on the surface.
• During a volcanic eruption, the _________
  dissolved in __________ rush out, carrying the
  magma with them.
• Inside a Volcano
• __________ ___________ The pocket beneath a
  volcano where magma collects

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• The magma moves through the _______, a long tube
  in the ground that connects the magma chamber to
  Earths surface.
• __________ - an opening in the volcano where
  gases and molten rock leave.
• __________ ________ The area covered by lava as
  it pours out of a vent.
• Crater A _________-__________ area that may
  form at the top of a volcano around the volcanos
  central _________.

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Characteristics of Magma

• __________ content, how __________ or _________
  the magma is, temperature and silica contents are
  important factors as to the __________ of a
  volcanic eruptions.
• The amount of ___________ in magma helps to
  determine how easily the magma flows. Silica is
  formed from the elements ___________ and
  ___________ and is abundant in the crust and
  ___________. The __________ silica content in
  magma the thicker the magma.

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Types of Volcanic Eruptions

• Silica content determines whether the volcanic
  eruption is ___________ or ___________.
• Quiet Eruption
• A volcano erupts quietly if its magma flows
  easily.
• Quiet eruptions produce two types of lava
• ________________ fast-moving, hot lava
• _____ cooler, slower moving lava

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• Explosive Eruptions
• If magma is __________ and __________, a volcano
  will erupt explosively.
• The explosion will break the lava into
  ___________ that quickly cool and harden into
  pieces of different size called ___________.
• Smallest pieces are called _________ (fine, rocky
  particles as small as a grain of sand),
  ___________ are pebble-sized particles and
  ___________ are larger pieces that range in size
  from a baseball to a car.

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Stages of a Volcano

• ____________ a volcano that is erupting or has
  shown signs that it may erupt.
• ____________ sleeping and may become active in
  the future.
• ____________ a volcano that is unlikely to
  erupt again.

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Other Types of Volcanic Activity

• Hot Spring forms when ______________ heated by
  a nearby body of magma rises to the surface and
  collects in a natural _________.
• Geyser a fountain of ___________ and __________
  that erupts form the ground.
• _____________ ____________ water heated by
  magma that provides a clean, reliable energy
  source.

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Monitoring Volcanoes

• Geologists have been somewhat successful in
  predicting eruptions. They use the same devices
  that are used to monitor earthquakes
  (______________, __________-___________ devices,
  etc.). Geologist will also monitor the small
  ____________ that normally accompany a volcano.

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Volcano Hazards

• Although quiet eruptions and explosive eruptions
  involve different volcano hazards, both types of
  eruptions can cause damage far from the craters
  rim.
• Volcanic ash can bury entire towns, damage
  ___________, and car _____________. Eruptions can
  also cause ___________ and _______________.