gvc1007.gvc10.virtualclassroom.org
Volcano Terminology
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Volcano
Fissure
Hot spot
Lava
Pahoehoe
Lapilli
Pillow lava
Volcanic ash
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Aa
Cinder cone
Magma
Stratovolcano
Vent
Composite
volcano
Mafic lava
Shield volcano
What is a volcano?
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Annotate and summarize the different
legendary views of what a volcano is.
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Which legend would you be more inclined
to believe and why?
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What do you think a volcano is?
What is a volcano?
Volcano:
an opening in the earth’s surface
through which lava, hot gases, and
rock fragments erupt.
Origin of Volcanoes
1.
2.
3.
Magma 80-160 km below the earth’s
surface slowly begins to rise to the
surface.
As the magma rises it melts gaps in the
surrounding rock.
As more magma rises a large reservoir
forms as close as 3.2 km below the
surface (magma chamber).
Origin of Volcanoes
4.
Pressure: from the surrounding rock
causes the magma to blast or melt a
conduit (channel) to the surface
where magma erupts onto the surface
through a vent (opening)
Origin of Volcanoes
5.
The magma, now called lava, builds up
at the vent forming a volcano
Origin of Volcanoes
6. Often the volcano sides will be higher
than the vent forming a depression
called a crater.
Crater:
Caldera:
an unusually large crater or the
remains when the cone collapses
into its own magma chamber
Anatomy of a Volcano
Cone:
the above ground structure
built from lava or tephra.
Mt. Kilauea in Hawaii
gvc1007.gvc10.virtualclassroom.org
Conduit:
the path that magma takes from
the magma chamber to the vent.
Magma Chamber:
the reservoir located under the
volcano where magma collects and
becomes the supply of magma/lava
to build the volcano
Lava
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Molten, solidifying rock on the surface of
the earth.
Solidfied lava is called?
Parasitic Cone:
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a smaller secondary volcano built
on the side of or near the main
volcano, but sharing the same
conduit to the magma chamber
Vent: opening of the volcano, through which lava,
ash and gases flow
Fumarole:
a secondary vent that emits
only gases
Fissure:
a long fissure (crack) from
which lava flows
Volcano Illustration
• Illustrate a volcano using these terms below.
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Cone
Crust
Mantle
Magma
Lava
Magma Chamber
Conduit
Vent
Fumarole
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Tephra
Gases
Parasitic Cone
Take a minute to
label the parts on
the diagram (not
all parts are
shown)
Crater
Ash Cloud/Gases
Parasitic Cone
mantle
Vent
Lava Flow
conduit
Magma chamber
Lava— There are 3 kinds:
Pahoehoe lava:
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Hot, thin, fast
flowing.
Hardens with a
relatively smooth
surface
Often has a ropy or
wrinkled appearance
Pahoehoe lava:
Aa lava:
 Cooler, thicker,
slow moving.
 Hardens with a
rough, jagged,
sharp edge
surface.
Pillow Lava:
 Lava suddenly cooled by
water.
 Shows sack-like segments
(stuffed pillows)
Can you identify the
kinds of lava from the
pictures?
Tephra:
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(pyroclastic, rock fragments)
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Three Types of Tephra:
1. Volcanic dust
2. Volcanic Ash
3. bombs
Types of Tephra:
Volcanic Dust:
Smallest particles and carried by
atmosphere circulation.
types of Tephra
Volcanic Ash:
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0.25-0.5 cm diameter
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Generally settles out within miles of the
cone but can be carried greater
distances by stronger winds.
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Forms a mudflow when mixed with water
Lahar (mudflow):
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mixture of ash, eroded land, and
water flowing down river valleys
Lahar (mudflow):
Types of Tephra
Bomb:
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Smaller bombs (gravel, pea size) are called cinders.
Walnut size bombs are called lapilli.
Larger fragments up to 4+ feet in diameter are
called bombs.
Types of Gases Expelled:
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water vapor, carbon dioxide,
nitrogen, sulfur dioxide,
hydrogen sulfide, chlorine
Bell Ringer: Volcanoes
1.
a.
b.
c.
2.
a.
3.
4.
What is the difference between the following:
lava and magma
fumarole and fissure
Pahoehoe, Pillow, and Aa lava
What is the following:
lahar
b. tephra
Identify the three classes of tephra.
What type of gases are ejected from a
volcano?
Infininte Campus: Update
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Earthquake Exam
Summary/questions over volcano legends )10pts.
Volcano Illustrations
Due on Monday:
 Seismic Graphing Activity
 Hotspot Worksheet
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Volcano Test-Tuesday
Post review on webpage tonight; pass-out on Monday
Types of Volcanic Eruptions
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Volcanic eruptions can be explosive or
quiet.
What two factors determine the type of
eruption a volcano can have?
Types of Volcanic Eruptions
What two factors determine type of eruptions?
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Amount of water vapor & other
gases in the magma.
The chemical make-up of the
magma.
Explosive Eruptions
Trapped gases under high
pressure will violently explode
when the magma reaches the
lower pressure of the surface.
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Granitic magma is very thick
and plugs the vent causing the
pressure to build until it blows
violently out the vent.
What type of magma is granitic
magma?
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The high water content of the
magma produces more water
vapor which when mixed in
granitic magma produces
explosive eruptions.
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Explosive Eruptions
Mt. Pinatubo
Mont serrat
Mt. St. Helens
Located on the island
of Luzon near the
Philippine Islands
An island located near
Puerto Rico and the
Dominican Republic
Located in
Washington State
Quiet Eruptions
Low pressure gas
 Has basaltic magma (is more fluid
and will flow instead of explode)
*What type of magma is basaltic?
 And has low water content.
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Location of Volcanic Activity
From the diagram, where do most volcanic activity occur?
scienceclarified.com
Locations of Volcanoes
Divergent Boundaries:
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As the plates move apart, long
cracks (rifts) form and lava builds
up forming volcanoes.
The long cracks are also called?
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If the divergent boundary is on
the ocean floor, volcanoes can
grow tall enough to break the
surface of the ocean and become
islands (Iceland)
Convergent Boundaries:
 Places where plates are moving
toward each other forming a
subduction zone.
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One plate melts under the other
and the magma moves upward to
form volcanoes.
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Example: Cascade Volcanoes
Convergent Boundaries: Volcanoes
 Example: Pacific Ring of Fire
Seismic Activity
blog.wolfram.com
In your notes, explain how the scientific evidence below
establishes a connection between volcanic and earthquake
activity.
blog.wolfram.com
Hot Spots
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Magma that may originate in the
mantle or outer core will move
upward, breaking the surface and
forming a volcano, they are
independent of plate boundaries and
a chain of volcanoes may form as the
plate moves across a hot spot.
Hot Spots
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(Examples: Hawaiian Islands and
Yellowstone National Park)
Types of Volcano Mountains
Cinder Cones:
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Small base, steep-sided, loosely
consolidated.
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Commonly built from gravel size lava rock
fragments called cinders.
Has violent eruptions and granitic lava sticks
rather than flows.
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Up to 1000 feet tall
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Life span of a few years.
Types of VolcanoEs
Cinder Cone Illustration:
Sketch a Cinder Cone Volcano:
Types of Volcano Mountains
Shield Volcanoes:
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Large base, gentle slope, lava rock
layers
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A few miles high
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Life span of a million years or more
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The lava is hot, thin, very fluid, often
basaltic.
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Example: Hawaiian Islands
Take a look at these examples:
http://ww.volcano.si.edu/world/tpgallery.cfm?category=Shield%20Volcanoes
The Mauna Loa volcano in Hawaii—
the largest volcano on Earth—has
the broad expanse characteristic
of shield volcanoes. It spreads
across half the island of Hawaii.
Shield volcano on Mars;
Taken from space
Shield Volcanoes
Mauna Kea
Sketch a sheild Volcano:
Types of Volcano Mountains
Composite (strato) Volcanoes:
Alternates between tephra and lava eruptions.
 Tephra adds height to the volcano and lava
cements the tephra together and adds to the
base.
 Located mostly in subduction zones
 Known to have violent eruptions.
 Life span of million years or more.
 Large mountain volcano often snow capped, a
few miles high
Examples: Mt Rainier, Mt Fuji, Mt Kilimanjaro
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Composite (strato) Volcanoes:
Mt. Fuji
Mt. Rainier
Seattle, WA
Honshu Island
of Japan
Mt. Kilimanjaro
Tanzania in Africa
Sketch a composite Volcano:
Types of volcanoes
Volcano Activity Levels (Stages)
Active (awake):
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Has erupted within the last 10,000
yrs. (historical time).
Pre-eruption activities:
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Increase in earthquake activity
under the cone.
Increase in temperature of cone
Melting of ice/snow in the crater
Swelling of the cone
Steam eruptions
Minor ash eruptions
Mt St. Helens, Washington State
Erupted in May of 1980
Dormant (sleeping):
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Eruptions have occurred in the
last 10,000 years, but little to any
activity is recently detected under
the cone.
Can become active and erupt again
after a “wake up” period.
Example: Mt. Rainier; Mt. Vesuvius
Mount Rainier
The most dangerous volcano in the US
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Primary danger is the formation of lahars
traveling down river valleys at a speed of
25mph and destroying everything in its path
100,000 people live on the solidified mudflows
of previous eruptions
Erupted 4xs in the last 4,000 yrs.
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Mount Vesuvius
•Erupted Last: 79 A.D.
Naples, Italy
Extinct:
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No eruption within recorded
history.
Not expected to ever erupt again.
No magma supply detected.
Example: Mount Mazama (Crater Lake),
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in Oregon.
Crater Lake