Living Things

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Volcanoes
Table of Contents Essential Question How Does A
Volcano Erupt? What happens when a volcano
erupts? What are the stages of Volcanic
activity? 6.2 Volcanic Eruptions Pgs 200-207
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Vocabulary 6.2

• Magma Chamber- The pocket beneath a volcano where
  magma collects.
• Pipe- A long tube through which magma moves from
  the magma chamber to Earths surface.
• Vent- the opening through which molten rock and
  gas leave a volcano.
• Lava flow- the area covered by lava as it pours
  out of a volcanos vent.
• Crater- a bowl-shaped area that forms around a
  volcanos central opening.
• Silica- a material found in magma that is formed
  from the elements oxygen and silicon it is the
  primary substance of Earths crust and mantle.
• Pyroclastic flow-
• Dormant-Not currently active but able to become
  active in the future (as a volcano)
• Extinct-A volcano that is no longer active and
  unlikely to erupt again.

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Pearson

• .
• Online Interactive Activity

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What Happens When a Volcano Erupts? Pg. 200

• Inside a Volcano
• All volcanoes have a pocket of magma beneath
  the surface, called a magma chamber, where the
  magma collects.
• Magma moves upward through a pipe, a long tube
  that extends from Earths crust up though the top
  of the volcano, connecting the magma chamber to
  Earths surface.
• Molten rock and gas leave the volcano through an
  opening called a vent.
• A lava flow is the spread of lava as it pours out
  of a vent.
• A crater is a bowl-shaped area that may form at
  the top of a volcano around the central vent.

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Volcanoe
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Fig. 1 Volcanic Eruptions pg. 201
Inside a Volcano A volcano is made up of many
different parts. Place each word in its proper
place in the diagram
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2 Types of Volcanic Eruptions pg. 202

• During an eruption, dissolved gases trapped in
  the magma expand, form bubbles, and exert great
  force.
• When a volcano erupts, the force
  of the expanding gases pushes magma from the
  magma chamber through the pipe until it flows or
  explodes out of the vent.
• Geologists classify volcanic eruptions
• as quiet
• or explosive.
• Whether an eruption is quiet or explosive depends
  in part on the magmas silica content and whether
  the magma is thin and runny or thick and sticky.

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Volcanic Eruptions pg. 202
The Wakulla Volcano was a column of smoke that
was last seen near Tallahassee in 1886. (no
volcanic activity in FL for millions of years)
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DO THE MATH!! Volcanic Eruptions pg. 202
Magma Composition Magma varies in composition. It
is classified according to the amount of silica
it contains. The less silica that the magma
contains, the more easily it flows. 1. What
materials make up both types? ____________________
______________ 2. Which type of magma has more
silica? How much silica does this magma
contain? __________________________________ 3.
Which of these magmas do you think might erupt in
a dramatic explosions? Why? ______________________
__________________________________________________
__________________________________________________
______________________
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Quiet Eruptions pg. 203

• Silica is a material found in magma that forms
  from the elements oxygen and silicon.
• Characteristics of a quiet eruption
• A volcano erupts quietly if its magma is hot or
  low in silica. The gases in the magma bubble out
  gently. The lava oozes quietly from the vent and
  can flow for many kilometers.
• Characteristics of an explosive eruption
• A volcano erupts explosively if its magma is
  high in silica. Trapped gases build up pressure
  until they explode. The erupting gases and steam
  push the magma out with incredible force. Both
  kinds of eruptions can cause damage far from a
  craters rim.

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Volcano Hazard pg. 205

• Volcanoes can cause great damage far from a
  craters rim.
• Quiet eruption lava flows, setting fire to
  everything in its path. They can cover large
  areas with thick layer of lava.
• Explosive eruption Dangerous chemicals are belch
  out from the volcano- such as hot rock and ash.
• A pyroclastic flow is a mixture of hot gases,
  ash, cinders, and bombs that flow down the sides
  of a volcano when it erupts explosively.
• Landslides of mud, melted snow, and rock can also
  form from an explosive eruptions.

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Did You Know?

• Stromboli volcano lies on an island off the coast
  of Italy. The volcano has been erupting almost
  constantly for at least 2,400 years! Expanding
  gases dissolved in magma cause the eruption to be
  nearly constant.

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What are the Stages of Volcanic Activity? Pg. 296

• Geologists often use the terms active, dormant,
  or extinct to describe a volcanos stages of
  activity.
• An active, or live, volcano is one that is
  erupting or has shown signs that it may erupt in
  the near future.
• A dormant, or sleeping, volcano is a volcano that
  scientists expect to awaken in the future and
  become active.
• An extinct, or dead, volcano is a volcano that is
  unlikely to ever erupt again.
• Hot-spot volcanoes may become extinct once they
  drift away from the hot spot

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• Geologist use special instruments to detect
  changes in the volcanoes.
• For example
• Tiltmeter- detects slight surface changes in
  elevation and tilt caused by magma moving ground.
  
• Geologist also monitor gases escaping from the
  volcano, small earthquakes before eruption, and
  rising temperatures in underground water.

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Fig. 5. Volcanic Eruptions pg. 206

• Cascade Volcanoes
• The Cascade volcanoes have formed as the Juan de
  Fuca plate sinks beneath the North American
  plate.
• Circle the 3 volcanoes that appear to be the most
  active.
• ________________________________________________
  _________________
• 2. Why migh geologists still consider Mount
  Jefferson to be an active volcano?
• __________________________________________________
  __________________________________________________
  _____________

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Volcanic Eruptions pg. 207
Magma at Mount Rainier
Mt. Rainier Mount Rainier is part of the Cascade
volcanoes. All past eruptions of Mount Rainier
have included ash and lava.