Year 3 Learning for test
1- Why do people continue to live in areas of volcanic and earthquake activity?
There are 3 main types of reasons to live in an area: (SEE)
- Social reasons (linked to people)
- Economic reasons (money)
- Environmental reasons (physical reasons)
(i) Why do people continue to live in areas of volcanic activity?
Why do people continue to live around Merapi (Indonesia)?
Although people know that living near the Merapi volcano is dangerous, they perceive that the risk is
worth taking. This is because material ejected from the volcano rapidly breaks down (weathers) into a
fertile soil that is rich in minerals needed to plant growth. The productive soil, which gives high crop yields,
has encouraged intensive farming. Added to this, the hot wet climate allows three crops a year to be
grown on the same piece of land. However, high yields have led to a high population density and a
shortage of available farmland. This means that, following an eruption, farmers in the Merapi region have
little choice but to return to their villages and rebuild their homes.
(ii) Why do people continue to live in areas of earthquake activity?
Learn 3 reasons, one for each type.
Type of reason
Environmental
Social
Economic
Social
Economic
Reason
Some places are known for their beauty and people buy houses in these areas
despite potential earthquake risks e.g. Malibu, California.
People believe that the chance of them being affected by an earthquake is very low.
Some earthquake areas like Turkey are popular tourist areas and provide many jobs
for the locals.
People in MIC’s and HICs feel safe in earthquake zones because of the advances that
have been made in earthquake proof buildings. For instance, since 1998 all mew
buildings in Japan have had to be earthquake proof.
Landslides, triggered by earthquakes, have caused loss of lives at many mining sites
around the world. The people consider the risk is acceptable as they can make a
good living for mining.
2- The causes and effects of volcanic eruptions on people and the environment, in Montserrat.
What were the causes?
Montserrat is located along a destructive plate boundary where the denser North American oceanic plate
collides with the Caribbean plate.
What were the characteristics of Montserrat volcanic eruptions?
Ash deposits: The volcano produced thick sticky lava called andesite which formed a dome at the top of the volcano
until it became so heavy that it collapsed formation of a huge ash cloud. Ash fell back on to some parts of the
island depositing ash 2-3mm thick:
Pyroclastic flows: Also when the dome collapsed, hot rocks, gases and ash were ejected from the volcano causing
pyroclastic flows- hot gas and rocks moving at 200kmph with temperatures around 400ºc.
What were the effects of the eruptions?
Effects on people
1- In August 1995, over 50 per cent of the population was evacuated to the north of the island as a precaution.
2- However, in June 1997: 19 people killed by a pyroclastic flow. Why?
-
were in the Exclusion Zone.
-
were too far away to hear the warning sirens - thought they would receive audible warning from the volcano
if it was going to erupt but this didn’t happen.
3- Of the 11,000 people who lived in Montserrat, 7,000 were evacuated.
-
Almost 3,000 to the island of Antigua
-
Nearly 4,000 to the UK
-
Some to the USA
Environmental effects
Pyroclastic flows:
- flattened thousands of trees.
-
- baked soil hard
-
- many rivers were blocked causing flooding
Ash and rock deposits:
-
- a total of 4 square kilometres of land was covered by the deposits.
-
- widespread destruction in Bethel due to large rock deposits.
3- Explain the methods used before and after Montserrat Volcanic eruptions to limit its effects. (6).
Learn TWO methods used to monitor the volcano:
Method
Sulphur dioxide
measurement
Seismometers
Tiltmeters
Explanation
Sulphur dioxide is produced by magma in large quantities and so its
emissions are monitored as they are a good indicator that magma is
near the surface
As the magma collects in the magma chamber, its movement creates
small earthquakes and tremors. Seismometers close to the volcano
record ground movements. E.g. In Montserrat, 14 seismometers used
to record ground vibrations.
Tiltmeters measure tiny changes in the slope angle of the ground e.g.
Five electronic tiltmeters record ground movement in Montserrat.
4- What can be done to limit the effects of earthquakes?
Preparation
(i) - Constructing buildings and roads to withstand earthquakes, Figure 22 page 28p Learn THREE
annotations.
(ii) - Education
In Japan, 1 September is Disaster Prevention Day. On this day emergency drills organised by local
governments are held throughout the country.
In the USA, information is given by the Federal Emergency Management Agency (FEMA) on how to prepare
for an earthquake. It states ways to plan ahead. Three of them are:
- Check for hazards in the home.
- Identify safe places indoors and outdoors.
- Have disaster supplies on hand.
Challenges for the planet
1- Why has the world’s climate changed since the last ice age? Learn pages 33 and 34 .Check that you
have completed the missing annotations in your book
2- The causes of climate change on a local and global scale, including the burning of fossil fuels and the
increase of methane in the atmosphere.
(i) The Greenhouse effect page 38
(ii) Increase of the amount of carbon dioxide:
Burning of fossil fuels
Fossil fuels produced from coal, oil and natural gas used to produce energy in power stations and to
supply fuel to vehicles.
When fossil fuels are burnt, carbon dioxide is released, increasing the amount of long wave radiations
absorbed by the atmosphere. For instance, in China 75 per cent of energy is produced from coal, the fossil
fuel which releases the largest amount of carbon dioxide.
The growth of the world population and the economic growth of newly industrialized countries such as
India and China explain an increase in the use of fossil fuels and in the amount of carbon dioxide released
in the atmosphere. There are many more cars on the road. For example, in Delhi, India, the number of cars
has grown from 5 million in 2001 to 15 million in 2014(1). Cars use fossil fuels to power them (1).
(iii) Increase of methane p37
3- Negative impacts of global warming
Effects at a global scale
Effects at a local scale
Changing pattern of crop yields 1-Countries Kenya: Droughts now happen every three
closest to the equator are likely to suffer the years instead of every ten years. In 2006
most as their crop yield will decrease.2- In
Kenya suffered its worst drought for 80 years.
Africa, countries such as Tanzania will have Many farmers lost all of their cattle.
longer periods of drought and shorter
growing seasons.3- This is due to hotter and
drier weather.
Rising sea levels (due to ice melting)1Tuvalu
Between 1993 and 2006 sea levels rose
Tuvalu, a group of nine coral atolls- ringlike
3.3mm a year. This will lead to an 88cm rise in coral island and reef that nearly or entirely
sea levels by the end of the century.2- This
encloses a lagoon- in the Pacific Ocean, has
rise will threaten large areas of low lying
started to evacuate its population to New
coastal land including major world cities such Zealand, with 75 people moving away each
as London.3- Many islands in the Pacific
year.
Ocean are already being affected by rising sea
levels
Retreating glaciers1- The vast majority of the Glacier National Park (USA)
world’s glaciers are retreating, due to the
Created in 1910- At the time there were 150
increase in temperatures caused by climate glaciers. Since then the number has
change2- 90 per cent of the glaciers in
decreased to 30. It is predicted that within 30
Antarctica are retreating.3- The melting of the years most, if not all, of the park’s glaciers
ice in the Arctic could cause the Gulf Stream will have disappeared.
to be diverted further south and this will lead
to colder temperatures in western Europe