2.1 Earthquakes and distribution of volcanoes

Question 1

what is the asthenosphere

Answer 1

Upper portion of the mantle - weak layer which can deform like plastic

Question 2

What is the crust

Answer 2

a very thin outer shell of the Earth

Question 3

Describe characteristics of oceanic crust

Answer 3

• thinner
• more dense
• formed of basaltic rock
• less than 200 million years old

Question 4

Describe characteristics of continental crust

Answer 4

• thicker
• less dense
• composed of granite rock
• up to 3.8 billion years old

Question 5

what is the lithosphere

Answer 5

rigid shell that differs in chemical composition, thickness and density

Question 6

What causes tectonic plates to move

Answer 6

convection current
ridge push
slab pull

Question 7

Where do earthquakes and volcanoes tend to occur

Answer 7

• plate boundaries
• same place as one another
• On the land, in the sea

Question 8

What is the mantle

Answer 8

made up of semi-molten rock called magma.

Question 9

Outline the difference between oceanic crust and continental crust

Answer 9

The oceanic crust is much thinner than the continental crust yet it is more dense. This means that the oceanic crust subducts under the continental crust at a destructive plate boundary and the friction causes it to melt. The oceanic crust is younger, less than 200 million years old, while continental crust is up to 3.8 billion years old, it is older because it is able to subduct and therefore melt.