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VOLCANOES
by Nate
Types of Volcanoes
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Shield Volcanoes
Shield Volcanoes are
volcanic mountains with
broad, gently sloping sides.
A shield volcano is made
from thin liquid.
Cinder Cone Volcano
Cinder Cone Volcanoes
are steep, cone-shaped
volcanoes. They are built
from lava fragments called
'cinders.'
Composite Volcanoes
A volcano is a geological feature where
a plate sinks, thrusting under the margin
ashes,gases, and molten rock form
of its neighboring plate. This is called
underground and erupt to the surface.
subduction. Subduction zones generate
Often when a volcano erupts, there is a
magma at a depth of about 60 to 90 miles
calm outpouring of lava. Some eruptions
by melting three kinds of material: oceanic
include rocks, clouds, and harmful gases. A
crust, ocean sediment, and asthenosphere
volcano erupts when tectonic plates push
caught in the corner between the
against each other and build pressure. The
converging plate. Divergent boundaries
volcano can’t hold the magma, and it
occur at mid ocean ridges. The plates
erupts. The Tectonic Plate Theory is the
move apart. The third type of boundary is
theory that explains the origin of most of
called strike-slip. Two plates grind together
the major features Earth’s surface. There
and slip past each other horizontally. New
are three main boundaries: convergent,
plate material is neither made nor
strike-slip, and divergent boundaries. A
destroyed.
convergent boundary is where the edge of
Dangers of Volcanoes
Volcanoes are harmful to the environment. Some volcanic eruptions include rock,
clouds, harmful gases and can cause earthquakes and aftershocks. Volcanic
eruptions occur most frequently at the edges of tectonic plates. Seventy-five percent of
the volcanic eruptions happen on the Ring of Fire.
Composite Volcanoes
are cone-shaped volcanoes
composed of layers of lava,
ash and rock debris.
Major eruptions
Mount Vesuvius caused the
destruction of Pompeii in
AD 79. The eruption
happened in Naples, Italy
and killed everyone there.
Mount Krakatoa erupted in
1883 in Indonesia. The
destruction took 36,000
lives from the inhabitants
of the the islands around
it.
Mount Pelee erupted on
May 8, 1902. It destroyed
the port of Saint Pierre and
killed 30,000 people.
Mt. St. Helens is located in
the state of Washington. It
erupted in 1980. The
destruction affected the
environment and killed 57
people.