Processes and landforms at plate margins

Question 1

How do earthquakes happen at destructive plate margins?

Answer 1

1. The denser oceanic plate is subducted beaneath the less dense continental plate
2. The plate gets stuck against eachother and tension builds
3. Eventually there is sudden movement
4. This sends shockwaves through the earth’s crust.

Question 2

How do earthquakes happen at conservative plate margins?

Answer 2

1. The plates get stuck against eachother and tension builds
2. eventually there is a sudden movement
3. This sends shockwaves through earth’s crust

Question 3

How do earthquakes happen at constructive plate margins?

Answer 3

1. The plates get stretched and tension builds up at faults whithin their crust.
2. Eventually there is a sudden movement
3. This sends shockwaves through earth’s crust

Question 4

How do volcanoes form at constructive plate margins?

Answer 4

1. Magma from the mantle rises through fissures in the crust
2. This magma spills out at the surface gently
3. overtime layers of lava from each eruption build up to form a gentle sided Shield volcano

Question 5

How do volcanoes form at destructive margins?

Answer 5

1. As the oceanic crust is forced into the mantle it breaks down into magma under the intense heat and pressure
2. The magma is forced upwards, erupting though the surface with explosive power
3. Over time, layers of ash and lava from each eruption build up to form a steep sided composite volcano

Question 6

How do ocean ridges for at constructive margins (Oceanic crust)?

Answer 6

1. Magma from the mantle fills the gap between plates as they move apart
2. this magma spill out at the surface gently
3. Over time layers of lava from each eruption build up to form a gentle-sided shield volcano
4. This happens right along the boundary forming a line of underwater volcanoes: a mid ocean ridge

Question 7

How do rift valleys form at constructive margins (Continental crust)?

Answer 7

1. Brittle continental crust fractures as the two plates move apart
2. Over time, areas of crust drop down between parallel faults to form valleys with upstanding horsts left between
3. This happens right alond the doundary forming an area of rift valleys

Question 8

How do volcanic island arcs form at destructive margins (with O+O / O+C)?

Answer 8

1. As the oceanic crust is forced into the mantle it breaks down into magma under the intense heat and pressure
2. The magma is forced upwards, erupting though the surface with explosive power
3. Over time, layers of ash and lava from each eruption build up to form a steep sided composite volcano
   4. This happens right along the boundary forming a chain of volcanoes which can breach the sea surface

Question 9

How do deep ocean trenches form at destructive plate margin?

Answer 9

As the oceanic plate is being forced down into the mantle it leaves a long, deep channel in the sea floor: a deep channel in the sea floor.

Question 10

how do young fold mountains form at destructive plate margins?

Answer 10

1. If both plates are made of continental crust, then they both have low density so not much subduction happens
2. Instead the crust is largely forced upwards, buckling and uplifting the sedimentry rock at the surface.
3. over time this forms a mountain range such as the Himalayas
4. This also happens between a continental and oceanic plate