homework read section 9.2 page 198 q 1-3. how and where volcanoes form section 9.1 write what is in...
TRANSCRIPT
HOMEWORKHOMEWORK
• Read Section 9.2
• Page 198 Q 1-3
How and Where How and Where Volcanoes FormVolcanoes Form
Section 9.1Section 9.1
Write what is in RED on the Write what is in RED on the handout providedhandout provided
Quick ReviewQuick Review
• What is magma?
• Why does magma rise?
• At what kind of plate tectonic boundary/ boundaries do we find volcanoes?
• Why do volcanoes form here?
Definition of VolcanoDefinition of Volcano
• Volcano: Both an opening in Earth’s crust through which molten rock, gases and ash erupt and to the landform that develops around this opening
Magma FormationMagma Formation
1. Decreasing pressure can lower the melting temperatures of materials in the asthenosphere (ex. Rift valley/mid-ocean ridge)
2. Increasing temperatures can cause materials in the astenosphere to melt. (ex. Hot spot)
3. Increasing water in the asthenosphere can lower melting temperatures (ex. Subduction boundaries)
Rise to the TopRise to the Top• Magma tends to rise to the surface
because it is less dense than the solid material surrounding it
• The traits of the magma and the rate at which is rises depends on the amount of silica
Please make this chart in your Please make this chart in your notesnotes
Volcano Location Reason Volcano Formation
Special Notes Examples
Row 1
Volcano Location Reason Volcano Formation
Special Notes Examples
Subduction Boundary
Divergent Boundary
Hot Spot
Row 2
Volcano Location Reason Volcano Formation
Special Notes Examples
Subduction Boundary
Collision between Oceanic/Continental
Or Oceanic/Oceanic
Divergent Boundary High temperature + low pressure = lots of magma
Hot Spot Hot molten magma from deep within the Earth rises up through the crust and reaches the surface
Row 3 Row 4 Row 5
Volcano Location Reason Volcano Formation
Special Notes Examples
Subduction Boundary
Collision between Oceanic/Continental
Or Oceanic/Oceanic
On plate that does not sink
Divergent Boundary High temperature + low pressure = lots of magma
Where the plates separate
Hot Spot Hot molten magma from deep within the Earth rises up through the crust and reaches the surface
In the middle of plates away from plate boundaries
Row 4
Volcano Location Reason Volcano Formation
Special Notes Examples
Subduction Boundary Collision between Oceanic/Continental
Or Oceanic/Oceanic
On plate that does not sink
oceanic/oceanic, forms “VOLCANIC ARC”
Divergent Boundary High temperature + low pressure = lots of magma
Where the plates separate
Most of these volcanoes are underwater
Hot Spot Hot molten magma from deep within the Earth rises up through the crust and reaches the surface
In the middle of plates away from plate boundaries
Hot spots do not move, but the crust does
Row 5
Volcano Location Reason Volcano Formation
Special Notes Examples
Subduction Boundary Collision between Oceanic/Continental
Or Oceanic/Oceanic
On plate that does not sink
oceanic/oceanic, forms “VOLCANIC ARC”
O/C: Cascades in California
O/O: Aleutians in Alaska
Divergent Boundary High temperature + low pressure = lots of magma
Where the plates separate
Most of these volcanoes are underwater
Mid-ocean ridge, Iceland
Hot Spot Hot molten magma from deep within the Earth rises up through the crust and reaches the surface
In the middle of plates away from plate boundaries
Hot spots do not move, but the crust does
Hawaiian Islands, Canary Islands, Yellowstone