tectonic cycle and distribution volcanoes

Question 1

what is the tectonic cycle

Answer 1

the constant formation and destruction of the earth’s crust

Question 2

what does plate tectonic theory describe

Answer 2

how the earths crust/lithosphere is split into large slabs called plates

Question 3

why do the plates move

Answer 3

heat from the earth core cause the upper mantle to low in huge slow moving convection currents in the upper mantle

Question 4

what does this form

Answer 4

destructive and constructive plate boundaries

Question 5

1.volcanoes at constructive plate boundaries e.g

Answer 5

mount hekla, Iceland

Question 6

where are most constructive boundaries found

Answer 6

under the ocean

Question 7

what happens at constructive plate boundaries

Answer 7

mantle currents pull the earths plates apart e.g. the eurasian plate is pulled away from the North American plate

Question 8

what does the sepration of plates form

Answer 8

a long split in the crust called a rift valley

Question 9

why does magma rise

Answer 9

to fill the gap created by the rift

Question 10

what happens when the magma reaches the surface

Answer 10

cools and forms a long ridge of volcanic mountains called mid ocean ridges

Question 11

example

Answer 11

Iceland is part of the mid Atlantic ridge

Question 12

2.volcanoes at destructive plate boundaries e.g

Answer 12

Mount Fuji, Japan

Question 13

where do volcanos occur

Answer 13

two oceanic plates collide e.g. the pacific plate collides with the philippine plate

Question 14

what happens here

Answer 14

one plate sinks beneath the other and is absorbed back into the mantle

Question 15

what is this process called

Answer 15

subduction

Question 16

what is the melted oceanic crust

Answer 16

less dense than the mantle and the recycled material rises through the cracks in the crust unit it reaches the surface through a vent to form a volcano island arcs

Question 17

what are these

Answer 17

curved chains of volcanic islands which mark the subduction zone

Question 18

what Is the magma at these destructive plate boundaries

Answer 18

very cidic and tends o form steep sided volcanic cones

Question 19

example

Answer 19

mount pinatubo in the philippine islands

Question 20

3.volcanpes at hotspots e.g.

Answer 20

the Hawaiian islands of the pacific

Question 21

what is magma sometimes able to do

Answer 21

reach the surface of the earth in the middle of a plate

Question 22

what is this location called

Answer 22

hotspot

Question 23

why do hotspots occur

Answer 23

a large fountain or plume of magma rises to the surface and forces its way through the crust to form volcanoes

Question 24

what do mantle plumes generally contain

Answer 24

very basic madam (less than 55% silica) which is not very gaseous and can flow for many kilometres

Question 25

what are the volcanic mountains that result

Answer 25

gently sloping and have very wide bases (shield volcanoes)

Question 26

what happens as the plates move over the mantle plume

Answer 26

new volcanoes form

Question 27

what happens to the existng one

Answer 27

gradually become less active and eventually extinct as plates move away from the plume

Question 28

example

Answer 28

Hawaii islands

Question 29

diagram