Transcript Y10UA3.5 Living there Dec7_8PP

Why do people live in
hazardous places?
Hazards and risks
• Hazard is the potential to cause harm;
• Risk on the other hand is the likelihood of harm (in
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defined circumstances, and usually qualified by some
statement of the severity of the harm).
E.g. Flour would not be considered by many to be a
hazardous substance. However, if a baker was exposed
over a period of time to airborne flour dust and/or dust
by skin contact, he/she could develop dermatitis (an
inflammation of the skin), conjunctivitis (inflammation of
the eyes), rhinitis (information of the nose) and even
asthma - inflammation of the lungs which can cause a
great deal of distress and may even by life threatening.
So flour is NOT a hazard, but in special circumstances it
can be a risk.
And risks need to be protected against – a mask for
instance
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So
• A natural event (e.g. earthquake, flood,
landslide, volcanic eruption, tropical storm)
that has the potential to cause damage,
destruction and death present as a natural
hazard.
• The risk of being in the area needs to be
considered.
• How frequently is there a risk? How
serious can it be? Is there anything that
can be done to reduce the risk?
• This is a risk assessment
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• So the long term aims of any area subject
to hazards is to
 Carry out risk assessments
 As a result of these assessments, adjust
behaviour – this could be implement training
and information, change building design,
change zoning laws, move settlements – lots of
things
 Improve prediction
This aspect of it will come into next
year’s work – the bit we have left out so
that we can spend time reviewing the
unit and tying up the loose ends! 4
So today’s lesson will be looking at why
people stay in these potentially very
risky places
• From the viewpoint of:
 Physical/ environmental
 Human/social
 Economic
• For each of these let’s consider volcanoes,
earthquakes and tropical cyclic storms.
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Physical/environmental that encourage
people to stay
• How often do these hazards arise?
• What are the positive environmental
points of these places?
• What are the negative ones?
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Human/social aspects that encourage
people to stay
• What about the people and the place they
live might attract them to stay?
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Economic influences that encourage
people to stay
• What the kind of financial influences
there might be?
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Why do people live near volcanoes?
• At first it may seem odd that people would want
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to live close to a volcano or any tectonic activity.
After all, volcanoes have a nasty habit of
exploding, discharging liquid rock, ash, poisonous
gasses, red hot clouds of embers, and generally
doing things that kill people.
Earthquakes shake you up quite a bit!
And storms can create their own kind of
mayhem.
Yet, throughout history, people have deliberately
chosen to risk all those hazards and live near
them, even on the slopes of active volcanoes that
have erupted within living memory.
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• They chose to live close to there because
they felt that the advantages outweighed
the disadvantages.
• Most volcanoes are perfectly safe for long
periods in between eruptions, and those
that do erupt more frequently are usually
thought of, by the people who live there,
as being predictable.
• Today, about 500 million people live on or
close to volcanoes and many millions more
live in earthquake zones and in the paths
of tropical storms
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What about living near a volcano (and
the potential of earthquakes too)?
• We even have major cities close to active
volcanoes. Popocatapetl is a volcanic
mountain less than 50 miles from Mexico
City in Mexico.
• In short, the main things that attract
people to live near active volcanoes are
minerals, geothermal energy, fertile soils
and tourism.
• Lets look at each one...
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Minerals
• Magna rising from deep inside
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the earth contains a range of
minerals.
As the rock cools, minerals are precipitated out and, due
to processes like the movement of superheated water
and gasses through the rock, different minerals are
precipitated at different locations.
This means that minerals such as tin, silver, gold, copper
and even diamonds can be found in volcanic rocks.
Most of the metallic minerals mined around the world,
particularly copper, gold, silver, lead and zinc are
associated with rocks found deep below extinct
volcanoes.
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Minerals
• This makes the areas ideal for both large scale
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commercial mining and smaller scale local
activities by individuals and small groups of
locals.
Active and dormant volcanoes have the same
mineralization, so like extinct volcanoes, they are
rich sources of minerals.
Hot gasses escaping through vents also bring
minerals to the surface, notably sulphur, which
collects around the vents as it condenses and
solidifies.
Locals collect the sulphur and sell it.
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Geothermal Energy
• Geothermal energy means heat energy from the
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earth.
It's unusual to use the heat directly, by building
your house on top of a steam vent for example,
because it's unpredictable, dangerous and messy.
The heat from underground steam is used to
drive turbines and produce electricity, or to
heat water supplies that are then used to
provide household heating and hot water.
Where steam doesn't naturally occur it is
possible to drill several deep holes into very hot
rocks, pump cool water down one hole and
extract steam from another hole close by.
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Geothermal Energy
• The steam isn't used directly because it contains
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too many dissolved minerals that could
precipitate out and clog pipes, corrode metal
components and possibly poison the water supply.
Countries such as Iceland make extensive use of
geothermal power, with approximately two thirds
of Iceland's electricity coming from steam
powered turbines.
New Zealand and to a lesser extent, Japan, also
make effective use of geothermal energy.
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Geothermal in Iceland [mini case study]
• Iceland has over 200
volcanoes and 800 hot
springs
• 10% of the land is lava
fields (see ahead to fertile soils)
• New land is being created all the
time as the Eurasian and North
American plate diverge.
• There are several ways in which
Iceland uses the volcanoes to
positive effects
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Geothermal in Iceland
• The hot water from the springs are carried by pipeline,
45 km, to Reykjavik, the capital. The water’s
temperature is 3000C.
There the people have cheap reliable energy which does
not damage the environment.
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• It is also used for
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recreational purposes
Blaa Lonio - The Blue
Lagoon. In the middle of
this huge lava field sits
this pool of seawater
naturally heated by the
geothermal activity below
the surface
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Electricity
• 26% of Iceland’s electricity comes from
Geothermal Power.
• Travel brochures say that Reykjavik “is
the most unpolluted capital in Europe.”
• It’s true what the postcards say - the city
is absolutely pristine. The air is crystal
clear.
• The geothermal electricity generation has
a lot to do with this.
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• Southeast of Reykjavik,
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the town of Hveragerdi
serves as a geothermal
farming centre for the
capital.
Puffs of steam coming
out of the ground all
over the place.
There were greenhouses everywhere, often
surrounded by steaming cracks in the ground.
The extreme climate of Iceland is actually able
to produce much in the way of tropical fruits
and vegetables with the help of geothermal
steam.
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• Iceland is Europe’s
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largest producer of
bananas and most come
from in or around
Hveragerdi.
Except for the
geothermal farms
everywhere, Hveragerdi
looked a lot like a small quiet town that would
have fit right in place in central England.
With its seemingly unlimited geothermal
energy combined with ample hydro-electric
power from glacial rivers, Iceland is looking
to become one of the first countries in the
world to do away with fossil fuels entirely.
Now if only the rest of us lived on a plate
boundary!
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Fertile Soils
• Volcanic rocks are rich in minerals, but when the rocks
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are fresh the minerals are not available to plants.
When they do become soils though, they form some of
the richest ones on the planet.
Places such as the African Rift Valley, Mt Elgon in
Uganda, and the slopes of Vesuvius in Italy all have
productive soils thanks to the breaking down of volcanic
rocks and ash.
The Naples area, which includes Mount Vesuvius, has
such rich soils thanks to two large eruptions 35,000 and
12000 years ago. Both eruptions produced very thick
deposits of ash and broken rocks which have weathered
to rich soils.
Today, the area is intensively cultivated and produces
grapes, vegetables, orange and lemon trees, herbs,
flowers and has become a major tomato growing region.
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Tourism
• Volcanoes attract millions of visitors every
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year, for different reasons.
As an example of the wilder side of nature,
there are few things that can beat seeing an
erupting volcano blowing red hot ash and rock
thousands of feet into the air.
Even the less active ones that are just puffing
out steam and smoke are impressive sights
and attract tourists from around the world.
Around the volcano may be warm bathing
lakes, hot springs, bubbling mud pools and
steam vents.
Geysers are always popular tourist
attractions, such as Old Faithful in the
Yellowstone National Park, USA. Old Faithful
is such a popular tourist feature that it even
has its own 24 hour Old Faithful webcam.
This one is in
New Zealand
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Tourism
• Iceland markets itself as a land of fire and ice,
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attracting tourists with a mix of volcanoes and glaciers,
often both in the same place.
The wild, raw and barren volcanic landscapes also attract
tourists who want to see what the early planet may have
looked like.
Tourism creates jobs in shops, restaurants, hotels and
tourist centres / national parks.
Locals economies can profit from volcanism throughout
the year, whereas skiing, for example, has only a limited
winter season.
In Uganda, a country trying hard to increase its tourist
industry, the volcanic region around Mt Elgon is being
heavily promoted for it's landscape, huge waterfalls,
wildlife, climbing and hiking and its remote 'get away
from it all' location.
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Building Materials
• Blocks of lava are
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used for building
materials
Granite is a volcanic
rock
Ash is used in cement
to build with.
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They stay there because there is
nowhere else to go – it is home
• Land is cheap in volcanic and earthquake zones.
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Some people are too poor to leave their home
(especially in LEDCs) – also poor education does
not explain why they should move further away
Even when people can afford to leave the area
they may be too attached to their homes to
leave. Their families have been there for
generations.
And there are so many people living in these
dangerous areas, that it would difficult if not
impossible to re-house them, especially as many
areas – like those near Pinatubo - that provide
food for so many other people.
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Science is getting better
• People feel safer with technological advances
• Monitoring equipment that can foretell volcanic activity
• They can measure
 the escape of gas (sulphur dioxide – bad egg smell)
 Small earthquakes which act as a warning
 Swelling of the sides of the volcano also warns of things to come
• Quakeproof construction techniques are becoming more
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advanced.
But so far we are no closer to being to time earthquakes
accurately but building resistant structure is improving.
But foretelling the effect of tropical storms is improving
all the time. At last those who feel the impact are
becoming better at constructing defences and saving the
lives of those who live in its path.
The building techniques are improving too.
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Looking at tropical storms
• There are no all embracing positives with
living close to an area subject to hazards,
as is the case with volcanoes.
• So what you need here is examples of as
many different reasons that have an
influence of at least one group in at least 2
or 3 places!
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Tropical storms
• Physical/environmen •
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• They don’t happen •
often
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• Many of the places •
have reasonable
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rainfall and are
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warm
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• Many have useful
land, near the sea – •
good for fishing
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Human/Social
Links to family
Links to culture
Local work
Links to location
Economic
Lack money to move
Farmers – own land
Local resources – fishing
Tourism
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