Exam Revision - Natural hazards

Question 1

What is a natural hazard?

Answer 1

A physical process of event which has the potential to cause loss of life and damage to property

Question 2

What is a climatic hazard?

Answer 2

Hazards caused by weather

Question 3

What is tectonic hazards?

Answer 3

Hazards caused by tectonic plates eg volcanoes earthquakes

Question 4

What is the theory of plate tectonics?

Answer 4

The earths crust is not complete like the skin of an orange. It is broken into several individual pieces called tectonic plates. These plates can be thought of as floating on the semi-liquid mantle below.

Question 5

Where are volcanoes found / earthquakes occur?

Answer 5

On or near plate boundaries.

Question 6

What are geomorphological hazards?

Answer 6

Hazards caused by the ground.

Question 7

What is a constructive plate margin?

Answer 7

Plates that are moving away from each other.

Question 8

What is a destructive plate margin?

Answer 8

Plates that move towards each other.
+The oceanic crust subducts underneath the continental crust - called the subduction zone.
+When two continental plates meet, ground is folded and forced upwards to create mountains.

Question 9

What is a conservative plate margin?

Answer 9

Plates that slide past each other [or in the same direction at different speeds]
+Crust isn’t created nor destroyed.

Question 10

What are the causes of earthquakes?

Answer 10

+Convection currents in mantle cause plates to move
+Plates are jagged - plates lock
+ Pressure builds up - a sudden release of energy occurs.
+Seismic waves released - earthquake occurs.

Question 11

How is a composite volcano made?

Answer 11

+By destructive plate margins

Question 12

How is a shield volcano made?

Answer 12

+By constructive plate margins

Question 13

What are the primary effects of earthquakes/volcanoes

Answer 13

+Buildings collapse
+People are injured or killed by falling masonry.
+Roads, railways, ports are damaged.
+Electricity cables, gas and water pipes are damaged, cutting of supplies.

Question 14

Why do people live in areas of risk from earthquakes/volcanoes?

Answer 14

+Fertile soils - volcanic ash is rich in nutrients.
+Geothermal energy - good for increasing renewable energy use - economical & efficient
+Tourism - attracts people who enjoy dramatic scenery

Question 15

What are the secondary impacts of earthquakes/volcanoes.

Answer 15

+They can trigger landslides and tsunamis - which can destroy more buildings.
+People left homeless - could die from hypothermia
+Shortage of clean water and sanitation - diseases cold spread.
+Blocked/destroyed roads - leads to blocking emergency vehicles
+Businesses destroyed - leads to lack of income and unemployment.
+Repairs can be expensive - weakens a country’s economy.

Question 16

What are the immediate responses to earthquakes/volcanoes?

Answer 16

+Rescue people
+Recover dead bodies to prevent spread of disease
+Set up temporary shelters
+Provide temporary supplies - water, food first aid.
+NGOs could assist in helping or foreign governments.

Question 17

What are the long-term responses to earthquakes/volcanoes?

Answer 17

+Rehousing
+Repair damaged buildings, roads, railways, bridges etc.
+Improve building regulations - so they can be more earthquake resistant to damage,
+Reconnect broken pipes, electricity etc.

Question 18

How did the Haiti earthquake affect the people?

Answer 18

3 million people affected. 
Over 220,000 deaths. 
300,000 injured. 
1.3 million made homeless. 
Several hospitals collapsed.
7 on the Richter scale [9] on mercalli

Question 19

What was the cause of the Christchurch earthquake?

Answer 19

The 6.3 magnitude earthquake struck New Zealand at 12:51 on 22 February 2011. The epicentre was 6 miles South East of Christchurch and the focus was very shallow at 3.1 miles. The earthquake occurred on a conservative plate margin where the Pacific Plate slid past the Australian Plate in the opposite direction. It was technically an aftershock from a larger earthquake in 2010 but the impacts were more severe.

Question 20

How did the Christchurch earthquake affect the people?

Answer 20

181 people were killed and around 2,000 people were injured.
Hundreds of kilometres of water and sewage pipes were damaged
80% of the city was without electricity
6.3 on Richter scale

Question 21

How did Christchurch respond to the earthquakes?

Answer 21

They were well equipped
+Their emergency services were well trained
+They put stricter building codes in place - eg deeper foundations, flexible materials
+made earthquake proof buildings and roads.
+proven to be very effective

Question 22

How did Haiti respond to the earthquakes?

Answer 22

Neighbouring Dominican Republic provided emergency water and medical supplies as well as heavy machinery to help with search and rescue underneath the rubble, but most people were left to dig through the rubble by hand.
Medical teams began treating the injured – temporary field hospitals were set up by organisations like the International Committee of the Red Cross.

Question 23

What are three types of natural hazards?

Answer 23

+Climatic hazards
+Tectonic hazards
+Geomorphological hazards

Question 24

What is a natural disaster?

Answer 24

A natural hazard that has already happened

Question 25

What is hazard risk?

Answer 25

The probability [chance] that a natural hazard occurs

Question 26

What do natural hazards have to do to count as a hazard?

Answer 26

Affect human activities

+The better a population can cope with an extreme event, the lower the threat

Question 27

Why are HICs better able to cope with flooding

Answer 27

+Because they can afford to build flood defences, evacuate people in a disaster and repair damage afterwards

Question 28

How is the Earth’s surface separated?

Answer 28

1]Crust
2]Mantle
3]Outer core
4]Inner core

Question 29

What two types of crust are plates made out of?

Answer 29

+Continental crust

+Oceanic crust

Question 30

What is Oceanic crust?

Answer 30

+Crust that is THINNER [5-10km] and more dense

Question 31

What is Continental crust?

Answer 31

+Crust that is THICKER [30-50km] and more dense

Question 32

Why are plates moving?

Answer 32

Because of convection currents in the mantle underneath the crust

Question 33

What are plate margins/boundaries?

Answer 33

The places where plates meet

Question 34

What are the characteristics of composite volcanoes?

Answer 34

+Acidic lava, which is very viscous (sticky).
+Steep sides as the lava doesn’t flow very far before it solidifies.
+Alternate layers of ash and lava. For this reason, they’re also known as stratovolcanoes. Strato means layers.
+Violent eruptions.
+Longer periods between eruptions.

Question 35

What are the characteristics of a shield volcano?

Answer 35

+basic lava, which is non-acidic and very runny
+gentle sides as the lava flows for long distances before it solidifies
+no layers, as the volcano just consists of lava
+less violent eruptions
+shorter periods between eruptions

Question 36

Explain the formation of a composite volcano?

Answer 36

+At destructive plate margins, oceanic plate goes under the continental plate because its more dense
+Oceanic plate moves down into mantle, where its melted and destroyed.
+Pool of magma forms
+Magma rises through cracks in crust called vents
+Magma erupts onto surface [called lava] forming a [composite] volcano

Question 37

Explain the formation of a shield volcano?

Answer 37

+At constructive plate margins, magma rises up into the gap created by the plates moving apart, forming a volcano.

Question 38

What do volcanoes produce?

Answer 38

+Ash
+Lava
+Volcanic bombs
+Pyroclastic flaws and lahars

Question 39

What is monitoring?

Answer 39

+When devices such as seismometers and lasers monitor earth movements - can be used in early warning systems to give a small but vital amount of warning before a large earthquake occurs.

Question 40

How can monitoring reduce risk from tectonic hazards?

Answer 40

+Scientists can monitor signs that come before volcanic eruption [such as tiny earthquakes, escaping gas and changes in shape of the volcano] - all mean eruption is likely.

Question 41

What is prediction?

Answer 41

When monitoring the movement of tectonic plates, scientists can forcast which areas should be prepared for one to occur.

Question 42

How can prediction reduce risk from tectonic hazards?

Answer 42

+Volcanic eruptions can be predicted if the volcano is well monitored.
+Predicting gives people time to evacuate, this reduces the number of injuries and deaths