Transcript Chp 18.3 Notes TYPES OF VOLCANOES & WHERE THEY …

Chp 18.3 Notes
TYPES OF VOLCANOES &
WHERE THEY OCCUR
Main Idea 1: Not all volcanoes are built
the same. A volcano’s shape is
determined largely by:
1. magma’s viscosity
2. force of any eruptions
3. amount of weathering
Composite Volcano
Describe: Large, symmetric volcano with sharp peaks,
& violent eruptions.
Magma: Very viscous
Eruption: Can be slow seeping or violent explosions.
Shield Volcano
Describe: have gradual slopes
& peaceful eruptions
Magma: Not very viscous
Eruption: Travels a long
distance.
Kilauea Shield Volcano
Cinder Cone Volcano
Describe: small volcano
with steep slopes and a hole
at top made of cinders
Caldera
Describe: A depression that
forms when a volcano collapses
on itself.
Lava Dome
Describe: volcano that forms from very viscous magma at
the peak of another volcano. Lava domes can act like a
cork and can eventually result in explosive pyroclastic
flows.
Magma type:
Very viscous (thick
& resistant to
Flow)
Mount St. Helens
Main Idea 2: Volcanoes occur in specific regions of Earth.
Subduction Zone Volcano:
Describe: where oceanic crust is
Pushing under continental crust.
Magma/Eruption: Very viscous
& can lead to violent eruptions.
Examples: Ring of Fire around
Pacific Rim where magma comes rising from mantle.
Mt. Pinatubo, AK Aleutian Chain are examples
Rift-Zone Volcano:
Where 2 plates are
diverging, spreading
apart, at an ocean ridge
or in the middle of
a continent.
example: African Rift
Valley.
Hot Spot Volcano:
Where magma rises through
a thin portion of the crust.
Example: Most famous
example is Hawaiian Islands.
the hot spot stays in same
place & ocean crust keeps
moving, so there is a
chain of islands.