Volcanoes and Plate Tectonics
EQ: Where are Earth’s volcanic regions?
Vocabulary
• Volcano – a weak spot in the Earth’s crust where molten material, or magma, comes to the surface
• Magma – a molten mixture of rock-forming substances, gases and water from the mantle
• Lava – magma that has reached the surface EQ: Where are Earth’s
volcanic regions?
Location of Volcanoes
EQ: Where are Earth’s volcanic
regions?
Location of Volcanoes
• 600 active volcanoes on land, many more under the sea
• Form in belts that extend across continents and oceans
EQ: Where are Earth’s volcanic
regions?
Location of Volcanoes• Ring of Fire
– Major volcanic belt– Formed by the many
volcanoes that rim the Pacific Ocean
• Most volcanoes form – At divergent
boundaries, i.e.Mid Ocean Ridge
– At Subduction zones– Hot spots
EQ: Where are Earth’s volcanic regions?
Volcanoes at Diverging Plate Boundaries
• Form along the mid – ocean ridge which is mostly underwater except in Iceland and the Azores Islands
EQ: Where are Earth’s volcanic regions?
Volcanoes at Convergent Boundaries
• Oceanic plate to Oceanic plate
As the crust subducts it melts back into magma. This new magma is less dense than the surrounding rock so it seeps upward through cracks in the crust forming volcanoes
Island Arc – string of islands The curve of the islands echo the curve of the deep ocean trench
Major Island arcs: Japan, New Zealand, Caribbean Islands
EQ: Where are Earth’s volcanic regions?
Volcanoes at convergent boundaries
Continental Plate and Oceanic Plate– Andes
Mountains– Volcanoes of
the Pacific Northwest in the US
EQ: Where are Earth’s volcanic regions?
EQ: Where are Earth’s volcanic
regions?
Hot Spot Volcanoes
An area where magma from deep in the mantle melts through the crust like a blow torch
Found in the middle of plates
Hawaiian Islands formed over a hotspot
Yellowstone National Park
EQ: Where are Earth’s
volcanic regions?
Hot Spot Volcanoes
EQ: Where are Earth’s volcanic regions?
Class Work and Homework
• Fill In– What did I learn– Confused– Say
Read section 3-1, Review and Reinforce
EQ: Where are Earth’s volcanic
regions?