1.1 plate tectonics

Question 1

what is the plate tectonic theory?

Answer 1

The plate tectonic theory helps us understand why and how plates move.

This explains that:
1. earth has a three-layered structure
2. The Earth’s crust is broken up into tectonic plates
3. Tectonic plates are constantly moving
4. Plate movements result in the formation of landforms like volcanoes, fold mountains and oceanic trench.
5. explains the occurrence of certain phenomena like earthquakes and tsunamis.

Question 2

structure of earth - inner core

Answer 2

1200 km thick, 3000-6000 degrees celcius , mostly iron and nickel in solid form

Question 3

structure of earth - outer core

Answer 3

3300km thick, 3000-6000 degrees celcius, mostly iron and nickel in molten form

Question 4

structures of earth - both mantles (upper & lower)

Answer 4

2900 km thick, 1000-3700 degrees celcius, layer of solid rock (upper) / solid rock (lower)

Question 5

structure of earth - continental crust

Answer 5

10-70 km thick , -14-1200 degrees celcius, consist of lighter rocks with less dense materials e.g. aluminium

Question 6

structure of earth - oceanic crust

Answer 6

6-10 km thick, -14-1200 degrees celcius, consists mainly of rocks with denser material e.g. besalt

Question 7

what are the forces responsible for plate movements

Answer 7

1. convection currents
2. slab-pull force

Question 8

how do convection currents lead to tectonic plate movement?

Answer 8

1. convection currents are movements of heat within the mantle
2. material in the mantle is heated by the core, causing the mantle to expand , rise and spread out beneath the Earth’s plates
3. This causes plates above the mantle to be moved apart
4. The hot mantle cools slightly as it moves away from the core
5. the cooled mantle is denser and it sinks to the core, pulling the plates along.

Question 9

how does slab-pull force contributes to tectonic plate movement?

Answer 9

when two plates converge, the denser oceanic crust is pulled down by gravity as it subducts beneath the less dense crust.
The denser oceanic crust sinks deeper into the mantle under its own weight, pulling the rest of the plate with it, contributing to further convergence