Transcript Volcanoes - Cobb Learning

Volcanoes
How they change the surface
of Earth!
Mt. Saint Helens
Before eruption
After Eruption
• A volcano is a weak spot in the
crust where magma is expelled.
• 2 Boundaries: divergent &
convergent.
Side by side
photo to
compare
before and
after the
eruption on
May 18, 1980
2 Types of Eruptions:
Explosive: More
rare than non
explosive
• More destructive
than nondestructive
• Blows molten rock
into the air
• Produces mostly
pyroclastic material
Not all Volcanos are so explosive
and destructive…
AA
Pahoehoe
Quiet Volcanos (non-explosive):
Most Common
Produced by calm flows of lava
Kilauea has
been
erupting
since 1983!!
While it can be
explosive at
times, it is
usually just a
constant flow.
Many times
the lava
flows into
the Pacific
Ocean and
cools to
create new
land.
Where are
more then half
of all the active
volcanos on
Earth located?
THE RING OF
FIRE
surrounding
the PACIFIC
PLATE.
Hawaii is not located close
to a plate boundary. So
how can it have so many
volcanoes??
It is located over a HOTSPOT!
So What is
inside of
the
volcano?
Magma chamber: is a body of
molten rock underground
Vent: cracks on the Earth’s surface
Silica and Magma
• The more silica that
magma contains, the
more explosive the
eruption.
• Pyroclastic material:
what forms when
magma is blasted into
the air and hardens.
Eruptions and Climate
Change
As volcanic ash and gases
spread through the
atmosphere, they can block
enough sun to cause global
temperatures to drop!
3 Types of Volcanoes
Shield
Volcano
Cinder
Cone
Volcano
Composite
Volcano
Shield: forms
from quiet
eruptions,
creates a widebased, gently
sloping
mountain
Cinder cone:
explosive
eruptions, tall,
narrow mountain,
and formed from
pyroclastic
material
Composite: formed from alternating
quiet and explosive eruptions. Also
called a Stratovolcano!
Landforms Created:
Craters-funnel shaped pits near
the top of a central vent
Crater Lake
Other landforms created:
Calderas- large semi-circular
depression that forms when
magma chamber below has been
emptied
Lava Plateau-a landform caused
by repeated eruptions of lava
spread over a large, flat area.
Active: smoking, active volcano;
lava, smoke coming out or very
soon
Dormant: sleeping volcano.
Nothing happening but could.
Extinct: dead volcano, unlikely to
erupt again
Where in our
universe is
the largest
volcano???
Answer:
MARS
Olympus
Mons
It is 3 times bigger
then Mt. Everest and
it is a shield volcano!