Download Effects of Eruptions

Inside of Old Smokey,
All covered with snow,
Lurk tons of hot magma,
Getting’ ready to blow,
Objectives:
From deep in the chamber,
Describe how volcanoes can affect people.
Up a vent to the top,
Describe conditions that cause volcanoes.
Like one great big zit that
Describe the relationship between volcanoes and
Earth’s moving plates.
Is soon going to pop.
The pressure keeps building,
And one day – KA-BLOOEY!
Out will blast lots of lava,
Red-hot and quite gooey.
Plus steam and sharp cinders,
Dark ash falling down,
If I lived near Old Smokey,
I’d get out of town.
MT.
ZITT
SAPO
PPIN
10 M
ILES
At this time, more than 600 are considered to
be active.
The largest in North America –
Mt St. Helens,
Most active in the world Kilauea, Hawaii.
The eruption of the century is considered to be
Mt. Pinatubo, Philippines (1991)
A volcano is an opening in
Earth’s surface. Mountains are
formed by the lava & volcanic
ash after an eruption.
Most are dormant which means
inactive.
Effects of Eruptions
• Lava is not the only thing about a volcano that is
dangerous to humans. When sulfurous gas mixes
with water vapor it forms acid rain that can kill
vegetation and therefore leaving animals with little
to eat.
• Pyroclastic flows is a common and devastating
result of some explosive eruptions. The flows are
fast-moving currents of hot gas and rock which
travel away from the volcano at speeds generally
as great as 450 mi/hr. The gas can reach
temperatures of about 1,800 degrees.
How do volcanoes form?
Magma forms deep inside Earth
because heat & pressure causes rock to
melt. Magma is less dense than other
rock & is forced upward.
Volcanoes form in three kinds of places.
Divergent Boundaries,
After thousands/millions of years it
reaches Earth’s surface & flows out
through an opening called a vent. The
steep walled depression around the vent
is called the crater.
Divergent boundaries are located where
plates are moving apart. They form long
deep cracks called rifts. When the
magma flows out it is called lava. The
lava is cooled quickly by the sea water
and sometimes build up to form islands
like Iceland.
ex. Mid-Atlantic Ridge
Convergent Boundaries,
&
Hot Spots
Convergent boundaries are where plates move
together. As part of one plate is pushed
down, it begins to melt and magma is forced
up to the surface.
Ex. Pacific Ring Of Fire & Mount Saint Helens.
Hot spots are not
located on plate
boundaries. They are
areas at the mantle’s
outer core that is
hotter than other areas.
Hawaiian
Islands
Magma is forced
upward towards the
crust.
Objectives:
Relate the explosiveness of volcanic
eruption to the silica and water vapor
content of its lava.
Describe three forms of volcanoes.
A quiet eruption occurs when a
volcano has basaltic magma
which contain less silica & is
very fluid. This means less
pressure.
ex. Kilauea
Pyroclastic Flow
A pyroclastic flow occurs
when an explosive
eruption hurls out a
mixture of hot gases,
ash, cinders, and bombs
(large cinders).
All eruptions are not the same. Some
are quiet and some are violent. The
severity of the eruption affected by
magma composition.
Granitic magma
contains a lot of
silica. It is very thick
& gas gets trapped in
vents causing
pressure. It also has
a high water content
which also creates
pressure.
Forms of Volcanoes
Shield Volcanoes
Cinder Volcanoes
Composite Volcanoes
They produce
quiet eruptions, and
contain basaltic
lava. They are
broad and it has
gently sloping
sides.
They produce explosive
eruptions and throws tephra
in the air. They typically have
steeps sides.
ex. Hawaiian
Islands
(Material that is thrown into the air by a
volcano.)
Composites vary between
quiet & violent eruptions.
These have alternating
lavers of tephra & lava.
6-3 Igneous
Rock Features
Objectives:
•Give examples of intrusive igneous
features.
•Explain how a volcanic neck and
caldera form.
Mount St. Helen's sequence of eruption
Sometimes magma forces its way
through cracks in the upper crust, but
does not reach the surface. The
magma cools and hardens into solid
rocks. Eventually, the erosion process
exposes the rock.
Batholiths
It is largest type of
intrusive igneous
rock. They form when
a large body of
magma cools
underground. Some
have been exposed
due to erosion.
YOSEMITE
STATE
PARK
Sill
Dike
A sill is when
magma is
squeezed
into
horizontal
cracks.
When magma
squeezed into
vertical cracks
and hardens.
Palisades over the
Hudson River
Volcanic Neck
Sometimes the
magma will
harden inside the
vent and become
solid igneous
rock. After the
cone has eroded
away it leaves
what we call a
neck.
Devils Tower
Wyoming
Caldera
When the top
of volcano
collapses into
itself.
Crater Lake