Transcript More Fun with plates

More Fun with plates
THE END IS NEAR! Volcano!
A little review
 The Surface of the Earth is made up of
very large plates that are moving
Is there really magma just below the
crust all around the world?
 No…
 Pockets of magma form and…
 Push, rise upward, less dense than
surrounding rock…
 Most forms at plate boundaries…
Plate Boundaries!!
 Convergent, divergent, transform fault
– but volcanoes only occur at certain locations…
 1 subduction (convergent)
 2 mid ocean ridges (divergent)
 3 hot spots
 Remember this map?
Map of where earthquakes and
volcanoes occur
A volcano can be….
 An active volcano is one that has erupted recently
or volcanologists see the possibility of an eruption
soon.
 A dormant or sleeping volcano is a volcano that
has been quiet for a long time, but still has signs it
may erupt again.
 An extinct volcano is one that has not erupted for
thousands of years. Sometimes it is hard to tell if a
volcano is dormant or extinct.
Volcanic eruptions can be…..
 Explosive
– Mt. St Helens
Quiet
Kilauea
What is released from volcanoes?
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Lava
Various gasses
Steam
Pyroclastic materials (tephra)
– Volcanic ash
– Volcanic dust
– Lapilli
– Pyroclastic bombs and blocks
What are the different types of lava?
 Mafic – flows easily
– Oceanic crust
– Dark when hardened
– pahoehoe,
– Aa
– Pillow lava
 Felsic
– Continental crust
– Light when hardened
Types of Lava
 Felsic, thicker flowing lava shows the
following behaviors:
– It tends to flow slowly, clog, and form semi-solid
blocks which resist flow
– It tends to entrap gasses, which form bubbles
within the rock as they rise to the surface
– explosive eruptions and is associated with
pyroclastic flows
 Lava with low viscosity, flows easily shows
the following behaviors:
– It tends to flow easily, forming puddles,
channels, and rivers of molten rock
– It tends to easily release bubbling gases as they
are formed
– Eruptions are rarely pyroclastic and are usually
quiet
Types of Lava
 There are three
forms of lowviscosity lava
flows: aā,
pāhoehoe, and
pillow lava. They
are described in
relation to basaltic
flows from Hawaii
pāhoehoe
 Pāhoehoe - Rope
– Looks like rope
Aa (AH! AH!)
 A`a (pronounced "ah-ah") is a Hawaiian
term for lava flows that have a rough rubbly
surface composed of broken lava blocks
called clinkers.
 Because the way the lava moves and the
clinkers, the lava leaves sharp and jagged
remains… this is where the name came
from.
Pillow Lava
 Forms underwater
 Rapid cooling makes it look like a pillow.
What are the different types of volcanoes?
 Shield
 Cinder cone
 Composite or stratovolcano
 Caldera
 Lava dome
Shield Volcano
 a broad, shallow volcanic cone
 mafic lava flows and cools slowly
 Kilauea, Hawaii is an example
Cinder cone volcano
 throws much ash into the air
 built up from alternate layers of ash and
cinder.
 Little or no lava emitted
 Paricutin, Mexico is one example
Composite
 Layers of lava and pyroclastic materials
 Often develop into high volcanic mountains
 create many vents that leave through the
smaller craters
 Ex: Mt St Helens
– Merapi, Indonesia
Caldera
 An older volcano with a large crater
which can be 62 miles(100km) wide. In
this crater many little new craters are
formed.
 VERY dangerous. Larger Caldera’s can
be very hard to notice at first.
 Signs of Calderas include hot springs, or
geysers
Dome Volcano
 This one has a steep, convex slope from
thick, fast-cooling lava
 Hint: It’s shaped like a dome
Researching your volcano…
 1 powerpoint slide with the following…
– All the info required in the table
– Date of most famous eruption
– Date of most recent eruption/activity
– Photo/picture
– Map showing location
– 2nd slide: bibliography
Fill in the table for your volcano
Name of
volcano
Location
Active, extinct, Eruption:
dormant?
Quiet or
explosive?
What was/is
emitted?
Type of
volcano
Damage
Volcanoes
Eyjafjallajökull, Iceland
Merapi, Indonesia
Kilauea, Hawaii
Mount St. Helens, Washington
Vesuvius, Italy
Pinatubo, Philippines
Paricutin, Mexico
Pelee, Caribbean
Krakatau, Indonesia
Etna, Italy
Katmai, Alaska
Santa Maria, Guatemala
Santorini, Greece
Your ppts here!!!
Largest eruptions ever…
 Can you name 3 of the top 20?
 http://volcano.oregonstate.edu/book/export/
html/227
 Deadliest eruptions?
 http://volcano.oregonstate.edu/deadliesteruption
Are there volcanoes in the US?
 Of course in
– Alaska
– Hawaii
– Also
– Western US!
Current Caldera
 Is the Yellow Stone
Caldera Growing?
– We don’t know
– We are currently
studying the caldera
Parts of a Volcano
 Dike – Magma/Lava that pushes out of the
main vent in a new direction. This does not
go along the bedding from older layers
 Sill – Magma that moves along the layers of
previous eruptions
 Vent – Main place lava escapes from
 Crater – opening in the volcano
 Magma Chamber- where gathering Magma
builds up pressure for the coming eruption
I would hate to have this guy’s
House
I think they mean it!!!!
Some people ARE crazy
What types of damage? How can
humans and animals die?
 Hit by pyroclastic flow
 Breathe in poisonous gasses
 Mud and ash slides, lahars when rains wash
down the accumulated ash
 Heat
What info, data can scientists
use to predict eruptions?
 Historical data
 Monitor air quality,
– Gasses that might be emitted
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Check local geology
Soil temperature?
Seismic activity
Bulging ground on, near volcano
Can volcanoes affect climate,
weather?
 gasses and ash
 more clouds form
 More of sun’s energy
is reflected back to
outer space
Less energy makes
it to earth’s surface
 Global cooling!
Ex: Krakatoa eruption, crop failures
OR
 Some volcanoes can release massive
amounts of Carbon Dioxide, methane and
other gasses.
 These gasses can trap heat within the
atmosphere,
 And increase the temperature of the planet.