Volcanoes
Chapter 10
Volcanoes and Earths Moving Plates
Section 10.1
Volcanoes and You
What is a Volcano?
Volcanoes and You
Volcano vent in Earths surface allowing lava and volcanic ash to erupt onto earth
What causes volcanoes?
What causes volcanoes?
Causes of Volcanoes:
Magma less dense than surrounding rock
Magma rises to surface
May take thousands or millions of years to reach surface
Opening is called a Vent.
Where do Volcanoes Occur?
Where do Volcanoes Occur?
3 types of plate boundaries:
Divergent plates move apart
Convergent plates move together
Transform-fault plate move side-by-side(parallel) to each other
Where do Volcanoes Occur?
Volcanoes Occur :
Along Divergent plate boundaries
Along Convergent boundaries
At hot spots
Where do Volcanoes Occur?
Divergent plate boundaries:
Plate move apart
mid-ocean ridge or rift valley are formed
Volcanic activity
Example: Iceland on mid-ocean ridge in Atlantic ocean
Where do Volcanoes Occur?
3 types of Convergent Plate Boundaries:
Ocean/Ocean
Continental/Continental
Ocean/Continental
Where do Volcanoes Occur?
Ocean/Ocean Convergent Plate Boundaries:
Two ocean plates come together
Subduction occurs lighter plate associated with the continent slides under the heavier ocean plate
A trench forms
A line of volcanic islands form, called an island arc.
Example: Japan
Where do Volcanoes Occur?
Continental/Continental Convergent Plate Boundaries:
Continents come together
Push up very tall mountains
Example: Himalayas
Where do Volcanoes Occur?
Ocean/Continental Plate Boundaries:
Ocean and continent come together
Heavier ocean plate slides under the continental plate(subduction)
Trench forms just off the coast
Ridge of volcanoes on the continent form
Example: Andes
Where do Volcanoes Occur?
What is a hot spot?
Where do Volcanoes Occur?
Hot spots are where some areas in the mantle are hotter than others, melting rock that works its way
to the surface.
Example: Hawaii
Energy From Earth
Section 10.2
Electricity from Geothermal Energy
What is Geothermal Energy?
Electricity from Geothermal Energy
Geothermal Energy Heat Energy from the Earth
Geothermal Energy from Magma
Water is heated by magma near the surface.
Geothermal Energy from Hot Dry Rock (HDR)
Water is heated by hot rocks(not magma)
Temperature increases with depth
High cost to drill
No pollution
Eruptions and Forms of Volcanoes
Section 10.3
Types of Eruptions
What are the two types of eruptions and what causes the two types?
Types of Eruptions
Quiet eruptions
Little water vapor or gas trapped in magma
Basaltic magma
runny
Explosive eruptions
Water vapor and gas trapped in magma
Granitic magma
Silica
thick
Forms of Volcanoes
List the 3 types of Volcano cones.
Forms of Volcanoes
Three types of volcano cones:
Shield
Gentle eruption
Basaltic lava
Flat layers
Broad volcano
Gentle slope
Forms of Volcanoes
Three types of volcano cones(cont):
Cinder cone
Explosive eruption
Granitic magma
Tephra different size harden volcanic material
Ash, cinder, blocks, bombs
Steep slope
Forms of Volcanoes
Three types of volcano cones(cont):
Composite
Changes between explosive to quiet
Igneous Rock Features
Section 10.4
List some intrusive features.
List some intrusive features
Batholith largest intrusive igneous rock reaches deep into earth
Lacolith smaller intrusive igneous rock near surface
Dike intrusive feature that cuts across across rock layers
Sill intrusive feature that squeezes between rock layers
Other intrusive features
Volcanic neck magma harden in the vent then the volcano erodes
Caldera top of a volcano collapses into magma chamber leaving a large opening
