Transcript Y10Ge U1B4 Hazards Nov 19 PP

Why do people live in
Tectonic areas?
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) 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
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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!
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
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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.
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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Geothermal in Iceland
• 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 only the rest of us lived on a
transcontinental plate boundary!
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Fertile Soils
• Volcanic rocks are rich in minerals, but when the
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rocks are fresh the minerals are not available to
plants.
The rocks need thousands of years to become
weathered and broken down before they form
rich soils.
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.
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Fertile Soils
• 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
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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
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becoming more advanced.
But so far we are no closer to being to time
earthquakes accurately
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• What To Do If a Volcano Erupts
• BEFORE:
Learn about your community warning systems and emergency plans.
Be prepared for the hazards that can accompany volcanoes:
Make evacuation plans.
If you live in a known volcanic hazard area, plan a route out and have a
backup route in mind.
Develop an emergency communication plan.
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In case family members are separated from one another during a volcanic eruption (a real
possibility during the day when adults are at work and children are at school), have a plan
for getting back together.
• Ask an out-of-state relative or friend to serve as the "family contact," because after a
disaster, it's often easier to call long distance. Make sure everyone knows the name,
address, and phone number of the contact person.
Have disaster supplies on hand:
Flashlight and extra batteries
First aid kit and manual
Emergency food and water
Non-electric can opener
Essential medicines
Dust mask
Sturdy shoes
Get a pair of goggles and a throw-away breathing mask for each member of the household
in case of ashfall.
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Keywords
• Remember: good geography marks come
from putting in enough keywords.
• And by quoting case studies which contain
real information – which often means dates
and other numbers!
• So what are the keyword for the last 4
weeks?
• To the whiteboard!!
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