Volcanic Activity

1
Volcanic Activity
2
What causes Volcanos to erupt?

• There are dissolved gases in magma.
• Dissolved gases trapped in the magma are under
  great pressure.
• The pressurized gases rise to the top and exit
  out of vents.
• During the volcanic eruption, the gases dissolved
  in magma rush out, carrying the magma with them.
• What does this sound in terms of the human body?

3
Volcanic Anatomy

• Side Vent Crater Vent Lava Pipe
  Magma Chamber

4
Characteristics of Magma

• The amount of Silica determines the thickness of
  the magma and the rate flow.
• Silica Compound of Oxygen and Silicon.
• High Silica Thicker magma
• Low Silica Thinner magma

5
Types of Volcanic Eruptions

• The amount of silica will determine whether the
  volcanic eruption is quiet or explosive.
• 2 types of eruptions
• Quiet Eruptions
• Explosive Eruptions

6

• Quiet Eruptions Low Silica, runny lava will
  cause quiet eruptions.
• Examples Hawaii, Iceland
• Pahoehoe Fast-moving lava that forms smooth
  rock as it cools
• AA Slow-moving lava that forms rough jagged
  rock formations.

7

• Explosive Eruptions High Silica, thick and
  sticky magma.
• The thick magma plugs up the pipe and at the
  crater.
• Trapped gases build up until they explode.
• Explosion breaks the lava into fragments that
  quickly cool and harden into pieces of different
  sizes.
• Pyroclastic Flow occurs when explosive eruption
  hurls out ash, cinders, and bombs as well as
  gases.
• Example Mt. St. Helens

8
Stages of a Volcano

• Active Living volcano that has/is/will erupt.
• Dormant Sleeping volcano that will awaken in
  the future.
• Extinct Dead volcano that is unlikely to erupt
  again.
• Hot Springs/Geyser groundwater heated by a
  nearby body of magma.