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?