Download Volcanic Eruptions

Volcanic
Eruptions
Volcano
• A system of passageways through which
magma moves.
Magma Chamber
•The pocket of magma
beneath a volcano.
Pipe
• A long tube in the
ground that connects
the magma chamber to
the Earth’s surface.
Vent
•Opening in which
gases and magma
leave the pipe.
Lava Flow
•The area covered by
lava as it pours out
of a vent.
Crater
• Bowl-shaped area that
may form at the top of
a volcano around the
central vent.
Pyroclastic Flow
• The explosive eruption
that hurls out a mixture
of hot gases, ash,
cinders, and bombs
(cooled pieces of lava).
Volcanic Eruption
1. Dissolved gases in magma are
trapped and pressurized
2. The pressure builds up
3. The pressure is released causing
the gases to expand
4. The expanding gases force the
magma to the surface
Kinds of Volcanic
Eruptions
1. Quiet eruptions
2. Explosive eruptions
Note: Some volcanoes experience
both quiet and explosive eruptions
Quiet Volcanic Eruption
• Low in Silica/Low Viscosity
• Magma flows out of vents
and cracks in the Earth’s
crust.
Explosive Eruption
• High in Silica/High Viscosity
• Magma builds up in pipe then
explodes out of the vents—
it will explode as pyroclastic
flow and sometimes lava will
flow at the same time.
Stages of Volcanic
Activity
1. Active
2. Dormant
3. Extinct
Active Volcano
A volcano that is erupting or
has shown signs that is
may erupt in the near
future.
Dormant Volcano
A volcano that is expected
to erupt in the near
future—basically it is
asleep…the gases are
building up and this takes
time.
Extinct Volcano
A volcano that will never
erupt again, or is
considered dead—
there is no magma
chamber so there are
no gases.