plate techtonics and Christchurch

Question 1

Risk

Answer 1

Is the probability of a hazard happening and creating a loss of lives

Question 2

Vulnerability

Answer 2

describes the risk of exposure to hazards combined with an inability to cope with them

Question 3

Resilience

Answer 3

the degree to which the environment can absorb a hazardous even

Question 4

3 ways to increase capacity to cope

Answer 4

1. having emergency evacuation
2. using earthquake proof buildings
3. land use planning

Question 5

2 Social impacts of the Christchurch earthquake

Answer 5

1. 184 people were killed and over 1500 injured in 2011 quake
2. 4 months after the earthquake around 50,000 Christchurch residents had moved permanently to other parts of NZ or Australia. (worse sense of community)

(however in the long term there was a net increase in population do to employment opportunities in recovery)

Question 6

2 economic impacts of the Christchurch earthquake

Answer 6

1. Some potential tourists may not travel to Christchurch now as the rugby World Cup could no longer be hosted (no multiplier effect)
2. Total loss to the NZ economy was estimated as £16 billion, which is about 13% of GDP

Question 7

2 Responses to the Christchurch earthquake

Answer 7

1. Christchurch used land use planning with
   The Green Zone – about 100,000 houses located here and these are likely to be rebuilt. However they are ‘rebuilt better’ – to reduce the impact of liquefaction the foundations are strengthened and piles can be driven 25m down to reach solid ground.

· Red zone – the worst affected residential areas – many along the valley slopes of the River Avon close to the inner city. Land in this area suffered badly from Liquefaction. The government agreed to buy over 5000 of the worst affected properties or the land on which they were built.

2. In the first few months much of the CBD of Christchurch was converted into a complex of shipping container boxes, each replacing services like shops, banks and fast food outlets

Question 8

focus

Answer 8

where the pressure from underground is released

Question 9

epicenter

Answer 9

the point on the ground directly above the focus

Question 10

Constructive plates

Answer 10

they move apart

Question 11

destructive plates

Answer 11

two plates move towards each other resulting in the denser of the two plates to subduct causing friction
——–>

Question 12

Conservative plates

Answer 12

Plates move in the same direction at different speeds. Friction the to get stuck. As pressure builds over time its can rebound and cause an earthquake.

• ————————->
• —————>

Question 13

how does sea floor spreading occur

ocean ridges

Answer 13

Seafloor spreading occurs at divergent plate boundaries.
1. As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense.

2. The less-dense material rises, often forming a mountain or elevated area of the seafloor.
3. Eventually, the crust cracks. Hot magma fueled by mantle convection bubbles up to fill these fractures and spills onto the crust. This bubbled-up magma is cooled by frigid seawater to form igneous rock. This rock (basalt) becomes a new part of Earth’s crust.

Question 14

how do volcanos occur at subduction zones

Answer 14

1. oceanic crust is melted when submerged into the magma
2. as it is light and dense it rises up back into the continental crust
3. these volcanoes are much more upright as the lava is andesitic which is more viscous and more explosive

Question 15

example of composite volcanoes

Answer 15

mt Șt helens in North America

steep sided

Question 16

where is the ring of fire

Answer 16

around the Pacific Ocean as it is a destructive plate boundary

Question 17

what type of plate boundary do rift valley’s formed

Answer 17

the occur at continental constructive plate boundaries
eg east African Rift Valley

These valleys are formed when the lithosphere stretches, causing it to fracture. The land between these faults then collapse into deep, wide valleys which are separated by upright blocks of land called horsts

Question 18

how are ocean ridges formed

Answer 18

The Ocean Ridge is formed when magma rising between diverging plates of the lithosphere cools and forms a new layer of crust.

Question 19

slab pull

Answer 19

This is simply the weight of the tectonic plate being subducted (pulled) below the overlying plate dragging the rest of the plate along behind it.

Question 20

ridge push

Answer 20

heat expelled by the magma expand the lithosphere and asthenosphere at the ridge, pushing them the surrounding ocean floor.

Question 21

explain the process of liquefaction

Answer 21

1. Liquefaction occurs when compacted sediments loses strength as a result of the stress such as shaking during an earthquake
2. material that is usually solid acts like a liquid
3. this loss of structure can cause damage to building as it acts like quicksand

Question 22

why was the preparation in Christchurch poor

Answer 22

The government was unaware of the plate boundary as the the boundary was covered by alluvium and therefore seismometers could not detect tectonic movement

Question 23

how do island chains form

Answer 23

1. island arcs are long chains of activity volcanoes (Hawaiian islands)
2. A hotspot is caused by a concentration of heat energy at the core of the Earth which is constantly heating the mantle above,
3. creating rising magma plumes through the cracks and a volcano may be caused
4. as the pacific plate moves at a northwesterly direction hotspot goes over more areas more volcanoes form

Question 24

features of shield volcanoes shield volcanoes formed

Answer 24

1. usually form at constructive plate boundaries

Question 25

what is a hazard

Answer 25

a potential risk to life or property

Question 26

examples of a land feature of a continental continental constructive plate boundary

Answer 26

1. east African Rift Valley

as the Somali plate moves apart from the African plate continental crust stretches and as it becomes weaker it drops down to create a valley.

magma can penetrate and form volcanoes

Question 27

examples of destructive plate boundaries in oceanic oceanic

Answer 27

Mariana island

Question 28

examples of constructive plate boundaries in oceanic oceanic

Answer 28

mid Atlantic ridge

Question 29

examples of destructive continental continental

Answer 29

Himalayas