Welcome to Science 10/25
• Get out your lab sheet. You have 3
minutes to create the type of volcano
listed on your card. Have your group help
you if needed.
• Today’s Schedule
• 1. Finish/Review Volcano Types Lab
• 2. Outline/Notes Volcanic Eruptions
• 3. Yokum Construction Co. will be open
for business to sell building materials.
Volcano Types
• Shield, Cinder-Cone, and Composite.
• What causes these different types of volcanoes
to form?
• The different ways in which they erupt and the
different materials that are erupted.
Volcanic Eruptions
Section. 3
Pele
I. Kinds of Volcanic Eruptions
• Eruptions are classified as either quiet or
explosive.
• How a volcano erupts depends on the gasses,
silica, and viscosity of the magma.
• Silica-similar to sand, one of the key components of
magma
• Viscosity- the resistance of a
liquid to flow
II. How the Eruption Works
• A volcanic eruption is similar to an exploding
pop can.
• Gasses inside the volcano build up. As gas
builds up, so does the pressure. When the
pressure is too great, the volcano erupts.
•
BBC NEWS | Science/Nature | Animated guide: Volcanoes
OUR RESTLESS PLANET
III. Quiet Eruptions
• Magma has low silica,
low viscosity, and low
gasses so it flows easily.
• Hawaiian Islands were
made this way.
•
OUR RESTLESS PLANET
• What type of volcano is
formed by quiet
eruptions?
• Shield
IV. Explosive Eruptions
• Magma has high-silica
and high viscosity,
making it thick and
sticky. High Gas.
• Magma does not flow.
• Builds up in the pipe
like a cork in a bottle .
• Pressure builds up until
the volcano explodes.
• :: Make a Volcano
Mount St. Helens
mt. st. helens - Google Videos#
During Eruption
Mount St. Helens
Before Eruption
After Eruption
"Mt. Saint Helens' Powerful Erruption"
Mt. St. Helens 2003
Mt. St. Helens 1984
V. Explosive Eruptions
• Explosive eruptions break lava
into fragments that quickly cool
into pieces of different sizes.
• Large pieces = bombs
• Small pieces = cinders
• Pyroclastic flow- mixture
of hot gas, ash, cinders,
and bombs
• -pyroclastic-flow-video.htm
VI. Stages of Volcanic Activity
• Active, dormant, or
extinct?
• Active- erupting or shows
signs of erupting.
• Dormant- may awaken in
the future.
• Extinct- unlikely to erupt
again
• Is a volcano ever really
extinct?
• No, at anytime a
volcano thought to be
extinct could reawaken.
How It All Starts
• Magma from the mantle
rises up through the crust
because it is less dense.
• Magma becomes trapped
beneath layers of rock.
• Weak spots in the crust
allow trapped magma to
reach the surface,
forming a volcano.
At the Surface
Pipe, Vent, Magma Chamber,
Crater, Lava Flow
• Magma Chamberpocket of magma
beneath a volcano
• Pipe- long tube that
connects the magma
chamber to the
surface
• Vent- opening where
molten rock and gas
leave the volcano
At the Surface
• Lava flow- area
covered by lava
as it pours out of
a vent.
• Crater- bowl
shaped area that
may form at the
top of a volcano.
Question of the Day
• Correctly the match the
stages of volcanoes with
the definitions.
• A. A volcano that is
unlikely to erupt again.
• B. A volcano that is
erupting or shows signs
of erupting.
• C. A volcano that may
awaken in the future
• Active
• Dormant
• Extinct
Today’s Objectives
• 1. Question of the Day
• 2. Open book quiz
• 3. Continue research on volcanoes