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Friday, 16 November 2012
Thursday, 15 November 2012
Iceland Unit Four Case Study
Volcanic islands formed on a constructive plate margin.
Iceland is
one of the most volcanically active countries in the world with 39 eruptions occurring
in or around Iceland in the 20th century. Around one third of all
basaltic eruptions in recorded history were found in Iceland.
Iceland is
situated along the mid-Atlantic ridge where the Eurasian and North American
plates are moving apart.Examples:
·
A fissure in Katla in 984 erupted to make the largest
basaltic eruption ever seen.
·
Laki in 1783 which was only second in size to Katla.
There have
also been several eruptions beneath glaciers which have led to glacier bursts. The
most recent was E15 in 2010.
E15 ß is a mountain glacier where the
glacier (over 100km2) covers the caldera of the volcano. Explosions
can also have secondary effects on outlet glaciers (connected glaciers) and
mountains as the power of the eruptions often lead to landslides, in 1967 there
was a massive landslide on the Steinholtsjökull glacial tongue. ß Earthquakes are likely due to
pressure of ice, violent eruptions even though they are basaltic. Massive ash
clouds and water jets are the most common result of eruption due to the glacier
above the vent of E15.
Q2 Landscape
An island
country, the main island is just south of the Arctic Circle and the country
itself is on the boundary between the North Atlantic and Arctic oceans.
E15 ß The summit is elevated 1,666ms
above sea level and the Caldera is filled by a glacier which is over 100km2
in size. The ash cloud created by E15 that covered Europe in 2010 was the
largest disruption to air travel since the Second World War. The eruption in
April ejected around 250million cubic metres.The Mid-Atlantic Ridge is part of the longest mountain range in the world as it is a part of every ocean stretching over 65,00kms. The ridge is a spreading centre (which means the sea floor expands with lava rising to the surface) and grows at a rate of around 2.5cms per year. The ridge was also central in the initial breakup of Pangaea.
Mountainous hilly landscapes with long slow slopes and peaks like waves, land may be suppressed by weight of glaciers. Land is rich in minerals and is therefore a biodiversity hotspot; basaltic lava is easily eroded away by glaciers. Fissures are common (e.g. Laki not a volcanic eruption but fissures either side) create wide flat plains with a stair like structure.
Q3 People
500 people
had to be evacuated as a result of the 2010 eruption but the population is so
low that even being a tectonic hotspot, there is little chance of disaster.
Laki’s eruption killed 50% of all livestock and 25% of the human population.
However,
globally Iceland has been known to have a bigger impact. The 2010 eruption
caused the largest disruption in air travel since the Second World War.
Laki’s
eruption also may have resulted in a global temperature drop due to sulphur
emissions. There was also estimated to be 6million deaths as a result
worldwide. There were also crop failures in Europe and droughts in India as a
result of the air pollution.
Q4 Management
There is
little that can be done to manage the eruptions but seismic activity is
recorded in order to predict any future eruptions. There are also evacuation
measures in place. Usually the European political systems are responsible for
this as being closer to mainland Europe than mainland North America they are
often associated together.
Sunday, 4 November 2012
The Great African Rift Valley A2 unit four case study
The East African Rift Valley
Q1 Tectonics
The rift itself was
formed by a combination of two key factors:
·
The
constructive/divergent plates: African and Arabian.
·
And
the magma plume beneath the plates.
The plume pushed up the land creating bulges and cracks allowing
flood basalts to rise through fissures and add to the gradient and create long
mountain ranges.
As a result of the divergent plates a small section of land
in between these plates breaks away and sinks leaving faults which are filled
and covered by lava (flood basalts)
Horsts and Grabens are therefore formed (raised land and
depressed land)
ß Secondary processes:
·
Shield
volcanoes formed in depressions (Grabens) as a result of weak thin crust. Magma
pushes easily to the surface, pure, easily eroded shield shaped structures.
·
Composite
volcanoes found on raised areas (Horsts) as a result of folding, faults form in
the thicker crust, magma pushes to the surface but faces obstruction: higher
pressure, explosive pyroclastic flows. ß Steep cone shapes.
·
As
a result of volcanoes and faults there is also a minor risk of seismic activity
in the area, mostly attached to erupting composite volcanoes.
Examples for each process named in the landscape section
below.
Information found from Geology.com and the article ‘East
Africa’s Great Rift Valley: A complex rift system.’
Q2 Landscapes
The Rift Valley
stretches over approximately 5000km from Syria to Mozambique. It is a massive
horst and graben structure with steep sided sloping mountains surrounding low
lying valleys that host lakes, deserts and shield volcanoes.
The width of the rift varies between
30-100kms and the depth also varies from a few hundred to a few thousand
metres.
The rift is 35million years old and is still growing meaning
that eventually East Africa including the horn of Africa: Ethiopia, Somalia and
Eritrea will break away and form its own continent (the rift being filled by
the sea.
Secondary landforms created as a result of the rift include
Mt Kenya 5,200m extinct and Mt Kilimanjaro 5,900m dormant, the two tallest
mountains (composite volcanoes) in Africa.
Erta Ale is also a volcano in the Rift Valley but instead is
a shield volcano that continuously erupts in the Afar depression. Being wide
with soft slopes it is only 613m high.
Q3 People
5 scientists were executed on by the Afar Tribe when trying
to visit the Erta Ale in January 2012. The tribes are uneducated and difficult
to reach, meaning they are vulnerable to tectonic activity.
Human Uses/Benefits:
·
Tourist
attraction i.e. beautiful scenery e.g. lakes, mountains, escarpments etc.
·
Lakes
in the rift valley provide fish.
·
Lakes
in the rift valley provide water for domestic and industrial use and irrigation
for agriculture.
·
Rain
shadow areas /areas with low rainfall provide pasture for grazing.
·
Lakes
are used for navigation.
·
There
is forestry on the slopes, so source of timber.
·
Gentle
slopes are used for arable farming and settlement.
·
Wildlife
conservation
·
Salt-water
lakes are used for mining.
·
Production
of geothermal electricity from underground.
Challenges:
·
Poor
means of transport and communications leaving rural areas without access to
services.
·
Shortage
of water due to high temperatures, geothermal activity basins.
·
Earth
quakes (tremors)
·
Little
rainfall /drought in the rain shadows areas.
·
Volcanic
eruptions, which destroy property and lives.
·
Poor
soils in areas of frequent eruptions.
·
Flooding
in depressions.
·
Salty
lakes because of high temperatures/high evaporation.
The rift valley lakes are essential to the African economy.
Lake Victoria is responsible for a large percentage of the Nile discharge
making arid land habitable. Being dependent on primary agricultural and fishing
industries, the continent is heavily reliant on the great rift lakes.
Q4 Management
The main management strategies involved in the rift valley
are environmental or conservation projects. The WWF is example of this,
attempting to protect animal and plant species from over fishing, pollution,
drought and fires. Conservation projects also exist in government schemes,
private reservations and local farming projects. Conservation is funded by
private and public organisations both internally and outside of the continent
as the area is of heritage value for the evolution of many species including
humanity.
Thursday, 1 November 2012
Energy Security First Ten Mark Answer
a) Explain the possible impacts on UK energy
security of the trends shown. 10mrks
There are issues facing the UK’s energy supply as facing the
order to cut CO2 emissions the British government seek out viable
alternatives. The UK is currently producing 400gs of CO2 per kg and is facing
the shutdown of British coal stations to meet the EU quota of 50gs, a 75%
decrease. The two possible routes currently hitting the headlines are either to
follow the original plan into costly renewables and cleaner nuclear sources or
to continue with business as usual by “dodging climate change targets” says
Livermore and “dash for gas”. In this essay I will explore the trends shown in
figure 1 and how they may indicate future insecurities.
The Overall trend in the amount of energy use shown in
Figure 1 is not dramatically changed. The amount has only increased by
20million tonnes (in equivalent of oil) between 1970 and 2030, not much when
the overall use in 2030 is expected to be a staggering 230million tonnes. This
does not indicate insecurity as such because the increase itself is not outside
of our capabilities to obtain the energy. We faced an increase double that (between
2010 and 2030) in the decades between 1990 and 2010. Therefore this increase of
around 9million tonnes should not be impossible. The problems however are not
with the overall figure but instead the individual energy sources within that
figure and how we intend to replace our losses to meet this projection.
Coal is the primary issue. Looking at the trend, shutting
down these stations in 2020 to meet targets should not be an issue as in the
last 60 years the UK has decreased its coal output by almost 100million tonnes.
However, coal still accounted for around 38million tonnes in 2010, the use of
coal in 2030 is still predicted to be more than the usage for renewables and
nuclear combined. In addition to the overall increase of around 9million tonnes
this leaves a large deficit that if not filled may lead to energy insecurity.
There are further issues implied by the trend shown for
nuclear power. The use of nuclear power has fluctuated in the past 60 years,
rising by 10million tonnes between 1970 and 1990, and then decreasing back
10million tonnes by 2030. This is because the first stations in operation at
1990 had a short life and are now beginning to expire. This poses an issue for
energy security in the UK as even with immediate investment into nuclear energy;
the stations take 15-20 years to build. This leaves a gap as shown in the trend
(nuclear only at 10million tonnes in 2030) where the UK will be without nuclear
power, irrelevant of investment into it. This is estimated in the chart to be
filled by an increase in natural gas and renewables.
However, there are also issues with these sources as natural
gas is either found in the UK’s North Sea or is imported in liquefied form from
Russia or Qatar. The source in the UK is quickly running out, meaning we must
soon rely on imported gas. Qatar is a Middle Eastern country and is politically
unstable. This may lead to energy insecurity as the import pathway for liquefied
gas may be easily disrupted by war or revolution. Dependency upon Russia also
makes our energy security vulnerable as the Russian government have been known
to use their energy exports for political leverage. If both of these countries
were to cut off supply and we were dependent on our own dwindling sources then
loss of natural gas may lead to energy insecurity.
Furthermore, HEP and other renewables are also unreliable as
despite the government’s religious investment into wind power the chart shows
that renewables will only be less than 5% of the overall energy use in 2030.
This is because renewables are expensive and only have a low output which is
not constant. Furthermore oil is almost one third of overall energy use and has
remained constant over the past 60 years being the same usage in 2030 as it was
60 years ago. This means the UK has always been dependent upon oil, making this
difficult to change. This also makes the UK vulnerable to energy insecurity,
not through physical scarcity but economic scarcity as OPECC control the UK’s
provision of oil and have been notorious for changing these prices (such as the
increase triple fold in 1977). Therefore these energy sources cannot be relied
upon and the UK’s energy remains insecure.
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