Download Volcanoes and Plate Tectonics

Volcanoes and
Plate Tectonics
What is a volcano?
 Volcanoes
are weak spots in the crust
where magma rises to the surface.
Location of Volcanoes
 Volcanic
belts form along the plate
boundaries.
 Volcanoes
Fire
occur in belts like the Ring of
Location of Volcanoes
 Most
volcanoes
occur along
diverging plate
boundaries or
in subduction
zones.
Volcanoes at Diverging Plate
Boundaries
 Volcanoes
form at the mid-ocean ridge
underwater
Volcanoes at Converging Plate
Boundaries
 Volcanoes
form in subduction zones
-
Two oceanic plates collide
-
An oceanic plate and continental plate
collide
Volcanoes at Converging
Boundaries
 If
subduction zone involves two pieces of
oceanic crust, volcanoes are created
 These
volcanoes create a string of islands
called an island arc
 If
Volcanoes at Converging
Boundaries
subduction zone involves oceanic and
continental crust, volcanoes are created
on land.
Hot Spot Volcanoes
 Hot
spot is an area where magma melts
through the crust like a blow torch
 Hot
spots are not often at plate
boundaries
Hot Spot Volcanoes
 Hot
spots volcanoes can be created in
the ocean floor
 Hawaii
Hot Spot Volcanoes
 Hot
spots can form under continents
 Yellowstone
National Park
Types of Volcanoes
 There
are three major types of volcanoes
 Shield
 Cinder Cone
 Composite
Shield Volcanoes
 Lava
slowly leaks onto crust and hardens
 Wide,
gently sloping mountains
Cinder Cone Volcanoes
 Steep,
cone-shaped hill or mountain
 Lava
is thick and produces ash and
cinders
 This
material piles up and forms the
mountain
Composite Volcanoes
 Tall,
cone-shaped mountain
 Layers
 Lava
of lava alternate with layers of ash
leaks out in between explosions
Lava Plateaus
 Sometimes,
 Lava
lava does not form mountains
flows out of crust and collects in
one area, forming a high plateau
Calderas
 Enormous
eruptions can empty the
magma chamber under the volcano
 With
nothing left for support, the
mountain collapses
Caldera
 The
hole left over is a caldera