hazards -plate margins + landforms

Question 1

how many plate margins are there?

Answer 1

4

Question 2

what are the 4 plate margins?

Answer 2

.destructive subduction
.destructive collision
.constructive
.conservative

Question 3

what happens at a destructive subduction plate margin?

Answer 3

.where oceanic crust meets continental crust at a destructive plate margin, then the denser oceanic crust subducts at an angle under the continent

Question 4

what landform occurs when oceanic crust subduct continental crust?

Answer 4

.deep sea trenches
.explosive volcanoes
.earthquakes

Question 5

what are deep sea trenches?

Answer 5

.they mark where one plate begins to descend beneath another
.they can reach great depths

Question 6

what other plates can cause destructive subduction?

Answer 6

.oceanic and oceanic

Question 7

what landform occurs when oceanic crust subduct oceanic crust?

Answer 7

.island arcs
.explosive volcanos
.earthquakes

Question 8

what are island arcs?

Answer 8

.a line of volcanic islands from offshore eruptions

Question 9

what happens at a destructive collision?

Answer 9

.continental crust and continental crust move towards each other

Question 10

what landform occurs at a destructive collision plate margin?

Answer 10

.fold mountains eg -Himalayan fold mountains where the Indian Plate collided with the Eurasian Plate
.shallow focus earthquakes

Question 11

what are fold mountains?

Answer 11

.as the plates move towards each other, their edges and the sediments between them are forced up creating fold mountains

Question 12

what happens as a constructive plate margin?

Answer 12

.plates move apart and new crust is created

Question 13

what landforms occur at a constructive plate margin?

Answer 13

.mid- ocean ridges eg -mid-Atlantic ridge
.shield volcanoes
.where plates move apart within a continent then rift valleys form eg -East African rift valley
.shallow focus earthquakes

Question 14

what are oceanic ridges?

Answer 14

.long continuous uplift features on the surface of the planet - a weak zone in the crust and an increase in heat near the surface causes hot crust to expand which forms a ridge

Question 15

what are rift valleys?

Answer 15

.the brittle crust fractures as sections of it move apart
.areas of crust drop down between parallel faults to form rift valleys

Question 16

what happens at a conservative plate margin?

Answer 16

.plates rub past each other, either in the same direction or in the opposite direction eg -san andreas fault

Question 17

what landforms occur at conservative plate margins?

Answer 17

.shallow focus earthquakes

Question 18

why do shallow focus earthquakes occur at conservative plate margins?

Answer 18

.friction between plates often locks the plates together for years -then the pressure is released which causes the earthquakes

Question 19

what landforms can occur not at plate boundaries?

Answer 19

.hot spots -near the centre of a plate

Question 20

how are hot spots created?

Answer 20

.the concentration of radioactive elements inside the mantle

Question 21

what happens at hot spots?

Answer 21

.plume volcanoes eg -haiwaian islands