Download What is a Volcano?

What is a Volcano?
A Volcano is a place where lava
reaches the surface
How does it happen?
Plate Tectonics & Hotspots
The pulling apart
of plates, causing
molten
Divergent
plate
boundaries
The
pulling apart of
plates, causing
molten rock to
come to the top of
the mantle. Causes
mainly submarine
volcanic activity
and creates new
oceanic crust.
rock to come to
the top of the
mantle. Causes
mainly submarine
volcanic activity
and creates new
oceanic crust.
The c The
collision of
plates, causing
Convergent plate
boundaries
The collision
of plates,
causing
Subduction
or one plate
to submerge
beneath the
other late to
submerge
beneath the
other plate to
submerge
beneath the
other ollision
of plates,
causing
Subduction or.
Hotspots
Located away
from tectonic
plates, over
mantle plumes
where pipes
vent magma.
Volcanoes
formed over
hotspot go
dormant and
new ones are
formed when
plates move
overhead.
Divergent Plate Boundaries
Most divergent plate boundaries are at the bottom of
the oceans, causing most of the volcanic activity to be
under water, thus forming new seafloor.
Convergent Plate Boundaries
•
•
•
When two plates (usually an oceanic and continental plate) collide,
causing the one plate to submerge under the other plate (called
subducting). In the case of oceanic-continental, a deep trench just
off shore is formed.
When the viscous magma, reaches the surface, a volcano is formed.
*This is what caused the typical Ring of Fire volcanoes.*
Oceanic - Continental convergence
Continental - Continental convergence
Oceanic - Oceanic convergence
Hotspots
Located over a mantle plume, where
the convection of the Earth’s mantle
creates a column of hot material that
rises until it reaches the crust. Pipes
form in the crust, which vents
magma.
Ring of Fire
Result of plate tectonics and the movement and hitting of crustal plates.
Area where large numbers of earthquakes and volcanic eruptions occur in a 40,000km
horseshoe shape. Contains 452 volcanoes, with over 75% of worlds active and
dormant volcanoes.
There are 3 types of Volcanoes
• Shield Volcano
• Cinder Cone Volcano
• Composite Volcano
Shield Volcano
• A gently-sloped
volcano
Cinder Cone
• A volcano made of
cinders that are blown
into the air
Composite Volcano
• A volcano built of
alternating layers
of cinders and
lava
What kind of volcano is this?
Diamond Head is an eroded
Cinder (Tuff) Cone
Early sailors mistakenly
thought glistening calcite
crystals inside the tuff rocks
were diamonds, leading to
the incorrect name.
Diamond Head formed
when hot magma rising up a
conduit hit ocean water,
causing large explosions
that threw exploded magma
particles (tuff) into a broad
ring.
What kind of Volcano is this?
Mount Shasta is a composite
volcano
Over the last 10,000 years,
Mt. Shasta has erupted on
average once every 800
years. During the 3,500
years the volcano has
erupted about once every
300 years. The most
recent eruption may have
occurred in 1786 A.D.
California
What kind of volcano is this?
Kohala is a shield volcano.
• Kohala is the oldest of
the subaerial volcanoes
that make up the Island
Of Hawaii. Kohala is
considered to be extinct
because it has not
erupted for 60,000
years.
Hawaii