Tectonic Hazards

Question 1

What is a destructive plate margin?

Answer 1

When continental and oceanic plates moves towards each other. the denser oceanic plate is subducted under the continental plate forming an ocean trench, and the continental plate folds to form mountains - earthquakes and volcanoes occur here.

Question 2

What is a constructive plate margin?

Answer 2

When plates move apart magma rises to the surface and cools to form new land, e.g. a mid-ocean ridge, which can cause volcanoes and earthquakes.

Question 3

What is a conservative plate margin?

Answer 3

When two plates slide past each other, either in opposite directions, or in the same direction but at different speeds. The plates can stick and jolt free causing earthquakes. There is no rising magma so no volcanoes.

Question 4

What affects hazard risk?

Answer 4

Poverty, urbanisation, farming, climate change.

Question 5

Poverty

Answer 5

Land is cheaper in risky places

Question 6

Urbanisation

Answer 6

People may be forced to live on steep slopes or flood plains.

Question 7

Farming

Answer 7

Farmers choose to live on floodplains or volcano slopes becasue of fertile land.

Question 8

Climate change

Answer 8

More extreme weather events in the future

Question 9

Continental drift

Answer 9

Crust broken into plates that move - used to be one ‘super-continent’.

Question 10

Convection currents

Answer 10

Theory that plates moved due to movement of magma in the mantle.

Question 11

Ridge push

Answer 11

New crust formed at constructive margins rises to form ocean ridges - older seafloor on either side slides away.

Question 12

Slab pull

Answer 12

At subduction zones older denser plates sink into the mantle - pulling newer/less dense bits of plate with it.

Question 13

Layers of the earth

Answer 13

Crust, mantle, core (inner core is solid - outer core is liquid) , lithosphere, asthenosphere.

Question 14

Continental crust

Answer 14

• 20-200km thick
• less dense
• mainly granite
• up to 3.8 billion years old

Question 15

Oceanic crust

Answer 15

• 5-10km thick
• very dense
• mainly basalt
• less than 200 million years old

Question 16

Primary impacts

Answer 16

The direct impacts (caused either by the earth shaking or a volcano erupting) - they happen during or immediately after the event, e.g. loss of life and numbers injured, buildings destroyed, transport infrastructure damaged, water/gas pipes breaking, electricity cables falling down; volcanoes - ash clouds covering everything, lava/ash contaminating water supplies.

Question 17

secondary impacts

Answer 17

The indirect impacts (caused by the primary impacts) - they happen in the coming hours, day and weeks, e.g. tsunamis and landslides. communities being cut off (from damaged roads), outbreaks of waterborne diseases (from contaminated water), fires and power cuts (from broken cables). BUT, also increase in tourism after volcanic eruptions, e.g. Iceland.

Question 18

Immediate responses

Answer 18

Emergency aid/assistance given within the first few hours/days - vital to reduce death toll, e.g. search and rescue, medical care such as pain relief and emergency surgery, temporary shelter, providing food and clean water.

Question 19

Long-term responses

Answer 19

Take place in the weeks and months after - focus on rebuilding and helping people return to normal lives, e.g. restoring essential utilities, repairing/rebuilding domestic and commercial buildings, repairing transport links. Also measures to reduce future damage.

Question 20

Monitoring

Answer 20

Using scientific equipment to detect warning signs, e.g. measuring changes in temperature and bulges in the volcano dome as magma rises, monitoring seismic activity.

Question 21

Prediction

Answer 21

Using historical evidence/live data to estimate when a tectonic hazard might happen, e.g. historical records show where earthquakes might occur, particularly is pressure is building up after no recent activity.

Question 22

Protection

Answer 22

Designing buildings/structures to withstand tectonic hazards, e.g. shock absorbers at the base of tall buildings to make them sway, cross-bracing and automatic window shutters.

Question 22

Planning

Answer 22

Identifying and avoiding places most at risk and preparing for a disaster, e.g. drawing up hazard maps, setting up ‘no-go’ areas, practising earthquake drills, stocking up on food, water and fuel, and knowing where to evacuate to.

Question 22

Why live in tectonic areas ?

Answer 22

• geothermal energy
• mining
• farming
• tourism

Question 23

Composite volcanoes

Answer 23

Found in destructive plate margins. Acidic lava. Steep sides

Question 24

Shield volcanoes

Answer 24

Found in constructive plate margins. Non-acidic lava. Gentle sides.