✅🟢Natural and Tectonic Hazards

Question 1

Natural Hazard meaning

Answer 1

A natural event that threatens people or has the potential to cause damage

Question 2

Natural hazard examples

Answer 2

Earthquake / volcanic eruption / flood / tropical storm

Question 3

Factors that affect natural hazard risk

Answer 3

Magnitude
Frequency
Location (steep slopes / active plate boundaries)
Population (high population = more people at risk)
Level of development / wealth - poorer communities = less money to prevent / invest in disaster management
3P’s

Question 4

What are the 3P’s and what do they do?

Answer 4

Protection (planning / preparation)
Prediction
Prevention

If the 3Ps are good = less of an impact from natural hazard

Question 5

What’s the plate tectonic theory?

Answer 5

The movement of the plates, and the activity inside the Earth, is called the theory of plate tectonics.

Question 6

Describe the Crust of the earth

Answer 6

Earths crust is broken into plates, either oceanic or continental. Once believed the convection currents in the mantle slowly moves the crust around, now though that a mechanism called slab pill drives the movement of tectonic plates.

Question 7

Describe earths structure

Answer 7

Inner Core - centre / hottest part of the earth - made of iron / nickel, temps up to 55°

Outer core - liquid layer surrounding inner core made of iron / nickel

Mantle - thickest section of the earth (2900km) molten rock - magma

Crust - outer layer of the earth - think (0-60km) either continental or oceanic

Question 8

What’s the slab pull / when does it occur?

Answer 8

Slab pull occurs where older, denser tectonic plates sink into the mantle at subduction zones. As these older sections of plates sink, newer and less dense sections of plate are pulled along behind. Sinking in one place leads to plates moving apart in other places.

Question 9

Tectonic plate meaning

Answer 9

Section of earths crust which land + oceans are above

Question 10

Plate margin meaning

Answer 10

Boundary between 2 plates
A plate margin marks the point where 2 of the earths tectonic plates meet. At these points the earths crust of either destroyed / creates / collides / slides past

Question 11

Oceanic vs Continental Crust

Answer 11

Oceanic is less than 200 years old
Continental is 1500millipm years old

Oceanic is thiner by 10x

Oceanic is denser therefore can sink

Oceanic - basalt
Continental - granite

Oceanic - can be removed / destroyed
Continental- can’t be removed / destroyed

Question 12

Destructive / convergent plate margins

Answer 12

Move towards eachother
Can be continental and oceanic

Oceanic and continental plates move together. The oceanic plate subducts under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes. Magma rises up through cracks and erupts onto the surface.

Earthquakes are violent here

Question 13

Constructive / divergent plate margins

Answer 13

occurs when 2 continental plates move apart / diverge. Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.
An example of a constructive plate boundary is the mid-Atlantic Ridge.

Gentle earthquakes

Mid Atlantic Ridge

Question 14

Collision zone

Answer 14

Collision zones form when two continental plates collide. Neither plate is forced under the other, and so both are forced up and form fold mountains.

Question 15

Conservative / transform margin

Answer 15

Sideways

Oceanic + continental crust slides past each other, presssure + friction from plate movements can build up if they get stuck due to friction. When they break apart energy is sent through the earth as shock waves in the form of an earthquake.
No margin crust created / destroyed

Sam Andreas fault

Question 16

What’s the global distribution of earthquakes / volcanic eruptions and their relationship to plate margins?

Answer 16

Earthquakes - along all types of plate margins.

Volcanoes - only constructive and destructive plate margins.

Question 17

What are the primary physical effects of a tectonic hazard - Christchurch?

Answer 17

Ground deformation

Question 18

What are the secondary physical effects of a tectonic hazard - Christchurch?

Answer 18

Liquifaction - 400,000 tons silt
Cliff collapsing
Tsunami

Question 19

What are the primary social effects of a tectonic hazard - Christchurch?

Answer 19

185 people killed

4000 injured

Question 20

What are the secondary social effects of a tectonic hazard - Christchurch?

Answer 20

1293 died in aftermath
Outmigration of 1/5 of population
Physiological impacts

Question 21

What are the primary economic effects of a tectonic hazard - Christchurch?

Answer 21

Pine Court Corpiration / CTV building fell
£40 billion total repair
Church fell down

Question 22

What are the secondary economic effects of a tectonic hazard - Christchurch?

Answer 22

Impact on school
Rugby World Cup impacted
Peoples money lost
Financial problems - people couldn’t work

Question 23

What are the primary environmental effects of a tectonic hazard - Christchurch?

Answer 23

Roads fractured
Debris / rubble on roads
Water pipes / telephone wires not working
Bridges broken

Question 24

What are the secondary environmental effects of a tectonic hazard - Christchurch?

Answer 24

80% of pipes / sewage couldn’t work properly

Roads filled with debris - unaccessible

Question 25

Primary responses to Christchurch earthquake?

Answer 25

Rescue crew 
Firefighters 
Survivors helping 
Media + news 
Farmer army clean up 
Domestic help 
300 Australian police came

Question 26

Secondary responses to Christchurch earthquake?

Answer 26

Community groups
Structural engineers
Green / orange / red / white zones
Temporary homes

Question 27

Compare : 
Christchurch New Zealand 2011
Kathmandu Nepal 2015

Answer 27

Christchurch - disaster plans in place / well trained emergency services / disaster drills / evacuation routes clear / food amount of equipment / well trained emergency crews - Death toll lower 185 / no one homeless / £40 billion repair cost

Kathmandu - disaster plans not in place / people unaware / people waiting for equipment to be flown in / poorly trained service crews- death toll higher 9000 / homeless = 3.5million / £10 billion repair cost

Question 28

Give economic reasons why people continue to live in areas at risk from a tectonic hazard

Answer 28

1. A good job / way of life May keep you in a danger zone
2. Sulphur can be mined in some volcanically active areas
3. The worlds best coffee is grown on volcanic soil in Columbia
4. Poor people (LIC’s) can’t afford to live away from volcanoes as they provide jobs (tourism)
5. Engineering can make people feel safe in these areas in richer parts of the world. Buildings can be made to be earthquake proof like the Bird’s Nest stadium in Beijing
6. Volcanic soils are very fertile - in Italy olives / vines / bits / lemons / oranges are grown near Mount Vesuvius

Question 29

Give social reasons why people continue to live in areas at risk from a tectonic hazard

Answer 29

1. Some places are well prepared for hazards so people feel safe
2. People in Mount Merapi (Indonesia) worship ancient spirits believing they will warn them of an eruption, on a full moon they throw items into the volcano crater to calm the volcanoes spirits
3. People believe the chance of the volcano erupting is slim
4. Many volcanic / earthquake events are infrequent so people don’t think they will experience a natural disaster
5. Volcanoes provide jobs / families and friends live there
6. A good way of life May keep you in a danger zone

Question 30

Give environmental reasons why people continue to live in areas at risk from a tectonic hazard

Answer 30

1. Some settlements have grown into enormous cities and would be hard to move anywhere else
2. In Iceland volcanoes provide cheap geothermal power (28% of all its energy) - can be used to heat pavements in the winter
3. Volcanic soils are fertile as the weathering of volcanic rock releases potassium into the soil which is essential for plant growth.

Question 31

What’s monitoring +How does it reduce the risks from a tectonic hazard?

Answer 31

Using scientific equipment to detect warning signs of events such as volcano / earthquake

Remote sensing - satellites detect heat / shape changes of volcano

Seismicity - seismographs record earthquakes

Gas - instrument detect gases related to magma rises

Ground deformation - laser beams measure volcano shape change

Question 32

Why are earthquakes harder to detect than volcanoes?

Answer 32

Usually they occur without warming but there’s evidence of water pressure changes / ground deformation / minor tremors prior earthquake

Scientists are yet to discover reliable ways to monitor / predict earthquake

Question 33

What’s prediction + how does it reduce the risks from a tectonic hazard?

Answer 33

Using historical evidence + monitoring scientists predict when / where a tectonic hazard may occur

Use scientific data / historical records on frequency

Prediction relies on monitoring

Question 34

What’s protection + how does it reduce the risks from a tectonic hazard?

Answer 34

Designing buildings that will withstand tectonic hazards

Volcanoes :
Embankments / explosives to divert lava away from property

Earthquakes:
Rolling weights on roof - control movement
Safe open areas for people to gather
Shutters that automatically shut
Rubber shock absorbers between foundations / above ground

Question 35

What’s planning + how does it reduce the risks from a tectonic hazard?

Answer 35

Identifying + avoiding places most at risk

Volcanoes:
Hazard maps for worlds most dangerous volcanoes - restrict certain land areas + identify land that needs to be evacuated + where to go if volcano erupts

Earthquakes:
Hazard maps for areas where earthquake will effect - high value land uses (hospitals / reservoirs) ab be protected in these vulnerable areas