Plate Tectonics: Why are areas more prone to tectonic hazards?

Question 1

What is the internal structure of the earth?

Answer 1

Core, Mantle, Crust

Question 2

What are the features of the earth’s core?

Answer 2

1. 3300 km thick
2. Mostly iron and nickel
3. Mix of solid inner and liquid outer
4. 4400-6600 degrees celsius

Question 3

What are the features of the earth’s mantle?

Answer 3

1. 2900 km thick
2. Mostly rock
3. Liquid inner and solid outer
4. 1000-3700 degrees celsius

Question 4

What are features of the earth’s crust?

Answer 4

1. 6-70 km thick
2. Mostly basalt and granite
3. Solid that melts under high heat
4. Similar temperature to environment it is found in

Question 5

What are the differences between oceanic crust and continental crust?

Answer 5

Oceanic
Location: Beneath deep oceans
Thickness: 5-8 km
Type and age of rock: Basalt, <200 million y/o

Continental:
Location: Beneath continents and shallow seas
Thickness: 35-70 km
Type and age of rock: Granite >4 billion y/o

Question 6

What are the processes that cause plate movement?

Answer 6

1. Convection currents
2. Slab pull force

Question 7

Describe the process of convection currents in causing plate movement

Answer 7

1. Core heats the mantle
2. Mantle expands and rises, spreading outwards beneath the plates
3. This drags plates along, causing plates to move
4. The mantle cools and sinks, pulling plates along
5. Mantle nears core and is heated again, causing the process to repeat itself

Question 8

Describe the process of slab pull force in causing plate movement

Answer 8

1. The dense, sinking oceanic plate at a subduction zone pulls the entire plate along due to its weight
2. This sinking plate drives the downwards moving portion of the convection current
3. Mantle that is away from the subduction zone drives the upwards moving portion of the convection current

Question 9

What are the types of plate boundaries? Briefly state.

Answer 9

1. Divergent
2. Convergent
3. Transform

Question 10

What are the types of divergent plate boundaries?

Answer 10

1. Oceanic-oceanic divergent
2. Continental-continental divergent

Question 11

What are the types of convergent plate boundaries?

Answer 11

1. Continental-continental convergent
2. Oceanic-oceanic convergent
3. Oceanic-continental divergence

Question 12

Describe the events that occur at an oceanic-oceanic divergent boundary and the associated landforms

Answer 12

1. Diverge
2. Fractures form
3. Magma rises to fill the cracks
4. Cools and solidifies
5. Forms new seafloow-> extends seafloor (seafloor spreading where newly formed rocks are closest to the ridge)
6. Forms a mid-oceanic ridge
7. Some forms undersea volcanoes
8. When the volcano builds up and becomes exposed above sea level, it forms volcanic islands

Question 13

Describe the events that occur at an continental-continental divergent boundary and the associated landforms

Answer 13

1. Diverge
2. Fractures form
3. Plates are stretched
4. Land between the faults sink
5. Rift valley is formed (linear depression with steep sides)
6. Block mountains are formed (Blocks of land standing higher than surrounding land
7. Active volcanoes and earthquake fractures may form along the rift valley as well.

Question 14

Describe the events that occur at an oceanic-oceanic convergence boundary and the associated landforms

Answer 14

1. Converge towards each other
2. Denser oceanic plate sinks under the less dense plate
3. Oceanic trench forms at the zone of subduction (may set off earthquakes due to friction)
4. Sinking oceanic plate melts in the mantle to form magma
5. Magma rises through the cracks and forms a volcano

Question 15

Describe the events that occur at an oceanic-continental convergence boundary and the associated landforms

Answer 15

1. Denser oceanic plate and less dense continental plate converge
2. Denser oceanic plate subducts beneath continental plate
3. Oceanic trench forms at zone of subduction
4. Fold mountains form on less dense continental plate as it buckles and folds
5. Melted mantle rises from the crust
6. Forms volcanoes on the continental plate
7. May set of earthquakes due to friction

Question 16

Describe the events that occur at a continental-continental convergence boundary and the associated landforms

Answer 16

1. Plates collide and push against each other
2. Resist subduction (too thick and buoyant)
3. Plates break and slide along fractures in the crust
4. Crust is compressed, forming a range of fold mountains by folding upwards and sideways

Question 17

Why do volcanos not form at continental continental convergence boundaries?

Answer 17

1. Plates are too thick for magma to pass all the way
2. No subduction hence no melted magma to supply the volcano