Download Volcanic Activity

How do volcanoes form and what affect do
they have on the Earth?
 Along
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
Above subduction zones
Magma forced upwards and forms volcanoes on
surface
Ring of Fire in Pacific Ocean
Mediterranean belt – Mt. Vesuvius
 Along

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
convergent boundaries:
divergent boundaries:
At mid-ocean ridges
Magma fills in gaps
Iceland – Mid-Atlantic Ridge
 Hot
Spots are
unusually hot
regions of Earth’s
mantle where
plumes of magma
rise to surface
 Located away from
plate boundaries
 Example: Hawaii
 Active

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
Erupts Regularly
Lifetime can span
months to millions
of years
Can be currently
erupting or showing
signs of unrest
(earthquakes,
emitting gas)
Ex: Mt. St. Helens
 Extinct
 Unlikely to erupt again
 No magma/lava supply
 Ex: Hawaiian Islands not
over hot spot
 Dormant
 Erupted
in past but is now
quiet
 Can be very dangerous

It is very difficult to
determine status of volcanoes
 Volcanoes
emit water vapor, carbon dioxide,
and sulfur dioxide into the air
 Gases are suspended in atmosphere and
block radiation from sun
 Global temperatures can be affected
 Health issues for humans (Respiratory)
 Pyroclastic flows, tephra, lahars (hot mud
flow)
 Volcanologists
study
deposits left from
previous eruptions
 Warning Signs:
earthquakes activity
and gas emissions
 Seismometers
measure EQs and
correlation
spectrometers
measure SO2 levels
 Structural
support
– walls, supportive
buildings
 Evacuation
procedures
 Communication
between scientists
and public
 Volcanoes
may have been present in the
history of other planets

Mars, Venus
 Volcanoes
are active on Jupiter's moon, Io