Natural Hazards

Question 1

What is a natural hazard

Answer 1

Natural hazards are sudden severe events which make the natural environment difficult to manage. They disrupt life and have huge social and economic impacts. They mainly fall into 3 groups: Atmospheric, geological and flooding

Question 2

What is a Hazard risk

Answer 2

hazard risk means the chance of being affected by a natural hazard. For example those living near the sea at risk of flooding caused by tropical storms of tsunami. People live in risky areas because they:
Accept the risk after weighing up advantages and disadvantages
have little choice of where to live

Question 3

Where do most earthquakes occur

Answer 3

Most occur at the margins of slow moving tectonic plates

Question 4

What are the 2 types of plates

Answer 4

Oceanic and continental

Question 5

Why do tectonic plates move

Answer 5

Because of convection currents

Question 6

Distribution of volcanoes

Answer 6

Volcanoes occur across plate margins but some occur at hot spots where the crust it thin and magma breaks through

Question 7

Why do people live at tectonic hazards

Answer 7

.Poor people have no choice
.Earthquakes and volcanic eruptions can be seen as rare so they’re not seen as a great threat
.Earthquake resistant buildings reduce risk
.Effective monitoring’s of earthquakes and tsunamis allow evacuation warnings to be given
.Plate margins often coincide with favorable areas for settlement and trade
.Some people have no knowledge of the risks
.Volcanoes can bring benefits such as fertile soil
.Earthquake fault lines allow for water to reach the surface
E.g San Fran is at risk of earthquakes but there is a good tech industry there

Question 8

How can risks from Tectonic hazards be reduced

Answer 8

.Monitoring
.Prediction
.Planning
.Protection

Question 9

What is global atmospheric circulation

Answer 9

Atmospheric circulation is a number of interconnected circular air movements called cells, these include:
.Sinking air which creates high pressure and rising air which creates low pressure
.Surface winds which move from high to low pressure, transferring heat and moisture from one area to another
.These winds curve due to the Earth’s rotation and change seasonally as the tilt and rotation of the Earth causes relative changes to the position of the overhead sun

Question 10

What is a tropical storm

Answer 10

Tropical storms have been called huge cyclones and typhoons in different parts of the world. They form 5-15 degrees North and South of the equator in Summer and Autumn where where:
.Ocean temperatures are highest
.The spinning (coriolis) effect of Earth’s rotation is very high
.Intense heat and humidity makes the air unstable

Question 11

How do tropical storms form

Answer 11

Rising air draws evaporated water vapour
up from the ocean surface which cools and
condenses to form towering thunderstorm
clouds.
The condensing releases heat which powers
the storm and draws up more water vapour.
• Multiple thunderstorms join to form a giant
rotating storm.
Coriolis forces spin the storm at over 120 km/h
(75 mph) creating a vast cloud spiral with a
central, calm eye of rapidly descending air.
• Prevailing winds drift the storm over the ocean
surface like a spinning top, gathering strength
as it picks up more and more heat energy.
• On reaching land the energy supply (evaporated
water) is cut off and the storm will weaken.

Question 12

How does global circulation affect the world’s weather

Answer 12

• Cloudy and wet in the UK because 60° north
is close to where cold polar air from the north
meets warm subtropical air from the south. These
surface winds from the south-west usually bring
warm and wet weather, because rising air cools
and condenses forming clouds and rain.
• Hot and dry in the desert because most deserts
are found at about 30° north and south where
sinking air means high pressure, little rain, hot
daytime temperatures and very cold nights.
• Hot and sweaty at the Equator because low
pressure marks where the sun is directly
overhead. Hot, humid air rises, cools and
condenses, causing heavy rain - hence the
tropical rainforests.

Question 13

The structure of tropical storm

Answer 13

Beyond the eye there are further banks of clouds and thunderstorms and occasionally tornadoes. There will also be strong gusty winds with heavy rain.
One either side of the eye is a tall bank of cloud called the eye wall. Here there are strong winds in excess of 120 km/h. Heavy rain, thunder and lightning
.The central eye can be seen clearly here. This is a small area where relatively cold air sinks towards the ground and warms up. There are no clouds here and the conditions are calm.

Question 14

What are the UK’s weather hazards

Answer 14

Thunderstorms, Prolonged rainfall, drought, Heavy snow, Strong winds

Question 15

How can monitoring help a country

Answer 15

Storms cannot be prevented but they can be monitored and their tracks can be predicted. This allows for warnings to be made and preparations to take place.

Question 16

How can protection help a country

Answer 16

Methods of protection often involve anticipation in design. They can involve buildings such as cyclone shelters which are ready to use in case of a natural hazards and can be further used as places of teaching, community centers or other uses.

Question 17

How can Planning help a country

Answer 17

It is unrealistic to stop tens of millions of people living in coastal areas to be at risk of tropical storms, but they can be made safer. It mostly means educating people on how to better themselves for survival to be able to respond correctly in case of a natural hazard.
E.g Japan hold an earthquake preparation day on Sep 1

Question 18

Evidence that UK weather is becoming more extreme

Answer 18

2003 - Heatwave
2007 - Floods
2008 - More floods
2009 - Heavy Snow
2010 - Heavy snow 
2013/14 - Floods 
2015/16 - Floods

Question 19

Why might extreme weather be on the rise

Answer 19

Global warming leads to:
.More energy in the atmosphere leading to more intense storms
.Global warming affects global atmospheric circulation which can bring floods to dry areas and heatwaves to cool areas

Question 20

Evidence for climate change

Answer 20

Shrinkage and changes in size for glaciers and ice at the artic
Rising sea level
Seasonal changes

Question 21

What are the 3 main causes of natural climate change

Answer 21

Orbital changes - Milankovitch cycles
Solar activity
Volcanic activity

Question 22

Explain the Orbital changes

Answer 22

Eccentricity - Every 100,000 years from circular to almost an oval (elliptical) shape
Axial tilt - Every 41,000 years the tilt of the Earth’s axis moves back forth between 21.5 degrees and 24.5 degrees
Precession - Over a period 26,000 years, the axis wobbles like a spinning top

Question 23

Explain solar activity

Answer 23

Over a period of 11 years dark patches on the sun known as sunspots mark short term regions of reduced surface temperature. They are usually accompanied by explosive, high-energy solar flares including heat output

Question 24

Explain volcanic activity

Answer 24

Volcanic ash can block out the sun, reducing temperatures on the Earth, this is a short-term impact. Sulphur dioxide is blasted out which converts to droplets of sulphuric acid and acts like mirrors which reflect solar-radiation back into space. The longer-term impacts reduces temperatures

Question 25

What is the natural greenhouse effect

Answer 25

Greenhouse gases such as carbon dioxide and methane trap heat that would otherwise escape into outer space. It allows short-wave radiation from the sun to enter earth and it traps long-wave radiation into earth.

Question 26

Human impact and the greenhouse effect

Question 27

What are the 3 cells of Global Atmospheric Circulation

Answer 27

Hadley cell, Ferrell Cell, Polar Cell

Question 28

Hadley Cell

Answer 28

At the equator (0-30) the ground is intensely heated by the sun. This causes the air to rise which creates a low-pressure zone on the Earth’s surface. As the air rises, it cools and forms thick cumulonimbus (storm) clouds. This causes:
.The air to separate and start to move both north and south towards the poles.
.When it reaches about 30° north and south, the air cools and sinks towards the ground forming the subtropical high-pressure zone.
.As the air sinks, it becomes warmer and drier. This creates an area of little cloud and low rainfall, where deserts are found.
.The Hadley cell is then complete. The air completes the cycle and flows back towards the equator as the trade winds.

Question 29

Ferrel Cell

Answer 29

(30-60 degrees)
.Air on the surface is pulled towards the poles, forming the warm south-westerly winds in the northern hemisphere and north-westerly winds in the southern hemisphere.
.These winds pick up moisture as they travel over the oceans. At around 60 degrees N and 60 degrees S, they meet cold air, which has drifted from the poles.
.The warmer air from the tropics is lighter than the dense, cold polar air and so it rises as the two air masses meet.
.This uplift of air causes low pressure at the surface and the unstable weather conditions that are associated with the mid-latitude depressions. Much of our wet and windy weather in the UK is determined by this.

Question 30

Polar Cell

Answer 30

At the poles, air is cooled and sinks towards the ground forming high pressure, this known as the Polar high. It then flows towards the lower latitudes. At about 60 degrees N and S, the cold polar air mixes with warmer tropical air and rises upwards, creating a zone of low pressure called the subpolar low. The boundary between the warm and cold air is called the polar front. It accounts for a great deal of the unstable weather experienced in these latitudes.

Question 31

What is the focus of an earthquake

Answer 31

The point inside the Earth’s curst where the earthquake originates from

Question 32

What is a seismic wave

Answer 32

A seismic wave is an elastic wave generated by an impulse such as an earthquake or an explosion

Question 33

What is the epicentre

Answer 33

The epicenter is the point on the earth’s surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins.

Question 34

How are the severity of Earthquakes measured

Answer 34

Using a Richter scale (rated 1-10 on intensity)
Using a seismometer which produces a seismograph
Using a Moment Magnitude Scale

Question 35

What does meteorological hazards refer to

Answer 35

Hazards that involve the weather, climate or atmosphere

Question 36

What is marginal land

Answer 36

Land that is hard to grow crops on

Question 37

What is magnitude another word for

Answer 37

Size

Question 38

What is a term used to describe a situation when a a hazard has happened and affected humans

Answer 38

Natural disaster

Question 39

Where are convection currents found in the layers of the Earth

Answer 39

Upper mantle

Question 40

How thick is the Earth’s crust

Answer 40

5-100km

Question 41

What do we call locations in which a hot mass of rising heat can be found under a weakness in a tectonic plate?

Answer 41

Hotspots

Question 42

What do we call the mudflows generated as secondary effects of eruptions?

Answer 42

Lahars