Tectonics

Question 1

Describe the convection current.

Answer 1

The heat from the Earth’s core causes the mantle to become less dense and rises towards the surface. The rising convection currents spread beneath the plates and drag them apart resulting in divergent plate movement.
The mantle material then loses heat and sinks towards the core. The falling convection currents causes the plates to collide. The mantle material gets heat up again forming a convection current.

Question 2

Seafloor Spreading

Answer 2

Where two plates move away from each other at divergent plate boundaries, seafloor spreading occurs.
Magma from deep within the earth rises through the mid-ocean ridge and new oceanic crust is formed.

Question 3

What happens at divergent plate boundaries? (oceanic & oceanic)

Answer 3

Two oceanic plates move apart and the overlying pressure of the underlying mantle to melt causing forming Magma. Magma rises through the weak spots in the crust.

Question 4

What happens at divergent plate boundaries (continental & continental)

Answer 4

The continental plates move apart. Rocks eventually fracture to form parallel faults. The rock between these faults collapses to form a deep rift valley with steep sides. As the plates move apart, the decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma. Magma rises through weak areas in the crust to the Earth’s surface, forming volcanoes. Earthquakes occur as stress and tension are released when plates move.

Question 5

What happens at convergent plate boundaries? (oceanic & oceanic)

Answer 5

The more dense oceanic plate would subduct under the less dense oceanic plate the high pressure would force water out from the denser crust the water lowers the melting point of the mantle causing the mantle to melt forming magma, the magma rises through the weak areas of the crust to the Earth’s surface. Forming a chain of volcanic islands ( Mariana islands)

Question 6

What happens at convergent plate boundaries? (oceanic & continental)

Answer 6

The denser oceanic plate would subduct under the less dense continental, this causes a great depression. High pressure forces water out from the oceanic crust and the water lowers the melting point of mantle forming magma, the magma rises up through the weak areas of the crust to the surface of the Earth forming volcanoes. The enormous pressure cause the plate boundary to causes the continental plate to be uplifted and buckled forming fold mountains.

Question 7

What happens at convergent plate boundaries? (continental & continental)

Answer 7

The continental plates are too buoyant to subduct, thus subduction does not happen. The enormous pressure cause the plate boundary to causes the continental plate to be uplifted and buckled forming fold mountains.

Question 8

What happens at transform plate boundaries?

Answer 8

Stress caused by the plate movement produces a fault, which is a zone of fractures.

Question 9

Stratovolcanoes

Answer 9

• High viscous magma
• More explosive
• steep sides
• narrow summit
• lava flows through shorter distance
  e.g mount fuji

Question 10

Shield Volcanoes

Answer 10

• Low viscous magma
• Less explosive
• Gently sloping
• lava flows though longer distance
• Broad summit

Question 11

How to measure how volcano eruptions are measured.

Answer 11

• Volcanic Explosivity Index (VEI)
• Greater the volume of ejected material, the higher the VEI
• Greater the height of the eruption cloud, the higher the VEI
• Duration of the eruption, the longer the eruption, the higher the VEI

Question 12

Tectonic Hazards of volcanoes

Answer 12

• Tephra
• Lava flow
• Pyroclastic flows
• Lahars
• Volcanic Landslides/ gas

Question 13

Tectonic hazards of earthquakes

Answer 13

• Ground shaking
• Soil Liquefaction
• Landslides
  -Tsunami

Question 15

Volcanic gases

Question 16

Landslides

Question 17

Tsunamis

Question 24

Pyroclastic flows

Answer 24

Destroyshecosystem
- Huge areas of forest may be destroyed, resulting in biodiversity
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