Transcript Tectonic Terror

Tectonic Terror
Coping with earthquakes, volcanoes
and tsunamis.
Natural Hazards - Tectonic Hazards
Natural hazards are the risks we face due to nature. Drought, flooding and forest fires
are examples of natural events which may pose a threat, or hazard, to people.
The land surfaces and the seafloors of the Earth rest on tectonic plates. It is the
movement of the plates that causes earthquakes, volcanic eruptions and tsunamis.
They are known as TECTONIC HAZARDS.
Find out more…
Structure of the Earth
Plate Names and Locations
Plate Tectonics
How Continents Move
Volcano and Earthquake Distribution
Structure of the Earth
Even though the Earth looks and feels uniform and solid to us, this is actually not the case.
The Earth consists of four layers:
1.The crust is the thinnest layer of the Earth - it is between 5 and 50 km thick.
This is proportional to the thickness of the peel around an apple. This is the surface layer we live on and where
all our rocks, minerals and metals are found.
2.The mantle is the layer below the crust and consists of a plastic or viscous layer of molten rock. This material
is known as magma.
3.The outer core surrounds the inner core and is more solid than the mantle.
4.The inner core is solid, consisting of iron and nickel at a very high temperature.
Plate Tectonics
The crust of the Earth does not form a solid, unbroken layer. It is made up of interlocking
plates that grow, get smaller and move around the Earth's surface at a very slow rate - only a
few centimetres each year. If we go back about 300 million years, we find that the continents
and the oceans were not in the positions we know today.
In fact, the Earth had only one continent known as Pangaea and only one ocean known as
Pantallassa.
180 million years ago, the first split of the land mass resulted in two separate continents Laurasia in the north and Gondwanaland in the south.
How Continents Move
Constructive plate boundary
Convection currents move within the mantle. The currents well up under the
crust and "float" the plates away from each other. In the centre, welled up
magma solidifies, forming solid volcanoes along the plane of weakness of the
oceanic ridges.
This is known as sea-floor spreading.
Destructive plate boundary
As two plates meet or collide, the edge of one plate slides beneath another.
As the plate is pushed into the mantle, the plate melts and becomes part of
the mantle. This activity occurs along the edges of fold mountain belts such
as the Andes and the Alps.
This process is known as subduction.
Conservative plate boundary
These occur when two plates slide past each other horizontally. No crust is
added or lost, eg the San Andreas Fault in California.
Plate Names and Locations
Volcano and Earthquake Zones
Volcanoes
•
Volcano erupts in Hawaii (Video)
Helicopter footage of lava eruptions and
flows on the Hawaiian volcano, Kilauea.
•
Iceland volcano spews lava (Video)
A volcano at Eyjafjallajoekull in southern
Iceland continues to erupt under an ice
sheet.
•
Thousands flee Congo eruption
Fires rage as mile-wide river of lava
engulfs village
Hospitals are having to use every
available area to treat people
injured or affected by the
earthquake and tsunami.
Walking through a disaster zone a man and his son survey the
damage in their home town
Earthquakes
•
Earthquake Eyewitness Report
Teacher, Julianna Bozsik, describes her
experiences in the 1989 Loma Prieta
earthquake.
•
Earthquakes: why they happen
Earth tremors are going on all the time as
the planet's rocks boil and move beneath
us, but only some quakes do any damage.
Find out why ...
•
Distribution of earthquakes and volcanoes
An animated lesson on tectonic plate
movement, and how this leads to
earthquakes and volcanoes
Tsunami
•
•
•
We Lost Everything In A Second (Video)
Survivor testimony from Miyagi prefecture
recounts the devastating effect of the
Japanese tsunami
Rescue in Kesennuma (Video)
Following shocking amateur footage
filmed in Kesennuma, Jonathan Watts find
hope in the rescue of an elderly couple
from their home in the city
Japanese tsunami survivors return to
wrecked city (Video)
Camcorder footage shot by a resident of
Ishinomaki, Miyagi prefecture, chronicles
life as an evacuee following Japan's
earthquake and tsunami on Friday 11
March
This is a house found drifting in the Pacific Ocean following the massive earthquake and
tsunami which destroyed many coastal regions in northern Japan on Friday
By Rex
A girl is rescued from the flood waters in Kessennuma
Why People Live in Dangerous Places
You might think that sensible people would avoid dangerous places, but often
the opposite seems to be true. Why would they do that?
Today, about 500 million people live on or close to volcanoes. We even have
major cities close to active volcanoes, so lets look at four good reasons to live
near a dangerous volcano.
Minerals
Fertile Soil
Energy
Tourism
Geothermal Energy
•
Geothermal energy means heat energy from the 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.
•
The steam isn't used directly because it contains 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.
Thousands of people near the
Fukushima nuclear power plant have
had to be evacuated from their homes
because of the threat of radiation
poisoning. The reactor has suffered a
series of explosions and fires following
the earthquake
People look at evacuation lists in the
town of Natori hoping to see the names
of relatives who have been moved to
safety
Fertile Soils
•
•
•
•
•
Volcanic rocks are rich in minerals, but when the 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.
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.
A coffee bush growing
in volcanic soil - African
Rift valley
Tourism
•
Volcanoes attract millions of visitors every year. There are
few sights that can beat seeing an erupting volcano blowing
red hot ash and rock thousands of feet into the air.
•
Iceland markets itself as a land of fire and ice, attracting
tourists with a mix of volcanoes and glaciers, often both in
the same place. The wild, raw and barren volcanic
landscapes 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. Local 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 volcanic landscapes, huge
waterfalls and remote 'get away from it all' location.
Volcanic landscapes
are marketed as a
tourist attraction in
Uganda, Africa
Minerals
Magna rising from deep inside the earth contains a range of minerals. As the
rock cools, the movement of superheated water and gasses through the rock
deposit minerals at different locations. Thanks to volcanic activity, 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 below extinct
volcanoes. This makes the areas ideal for both large scale commercial mining
and smaller scale local activities by individuals and small groups of locals.
Active and dormant volcanoes have the same mineralisation, 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 may collect the sulphur and sell it.
Why Hazards Become Disasters
An earthquake or tsunami striking a place where
nobody lives, farms or visits isn’t a disaster for
humans. It is only when a natural hazard exists in an
area where we live or work that hazards have the
potential to become disasters.
Clearly, the best way to avoid tectonic disasters is to
keep away from areas where they may occur, but
we’ve already seen that there are often good
reasons to live in the danger zones – generations
may farm on fertile soils before the next eruption
does any damage, and if you want to catch fish, you
must live on the coastline.
So, what factors influence the size of a disaster?
A man on his bicycle – the only transport
available.
Economic Development
In developed countries, buildings are more likely to withstand earthquakes because they have
the money and knowledge to create safer buildings, and adapt old buildings to withstand shocks.
Less fortunate countries lack both the money and the skills, and the results speak for themselves.
In Kobe, Japan, a quake killed 5,000, yet a smaller quake in less developed Turkey killed 17,000.
Why Hazards Become Disasters
Urban or Rural Location
Urban areas have greater population densities than rural areas. If identical quakes
were to hit rural and urban areas with the same safety precautions, the city,
containing more people and buildings would be the worst affected location.
Distance From The Disaster
Earthquakes are most powerful at the
epicentre – the place on the surface directly
above the source. As distance from the
epicentre increases, the power of the shock
waves decreases.
Tsunamis are most powerful along the coast.
As they move inland they lose energy and
eventually run out of momentum.
Volcanoes discharge lava, ash and gasses. Lava and gas clouds stay fairly close to the
volcano, being ejected into the air or flowing from the vent. Ash clouds can travel
around the globe, but again, damage quickly reduces as distance from the volcano
increases.
This devastated place used to be the village of Aragama - now people are left to sort
through the debris of what used to be their homes, schools and offices
Why Hazards Become Disasters
Weather and Seasons
When disasters leave people injured,
homeless or trapped they are vulnerable
to the weather. More people will die in
very hot, cold, dry or wet weather than in
more pleasant and ‘average’ conditions.
Extreme weather also hampers rescue
efforts. In areas where heating is provided
by open fires and stoves, a disaster in
winter carries a greater risk of house fires
than a disaster in summer.
We’re living on the streets at the
moment – so we need shelter too.
ActionAid
Why Hazards Become Disasters
Time and Day of The Week
The time and day at which a disaster strikes
has an influence on human consequences.
Modern cities are packed with workers during
the day, but many go home in the evening.
Schools are occupied during the day, but
empty at night.
Office blocks are occupied during the working
week, but probably empty on Saturday and
Sunday.
Some children in Japan's capital city Tokyo have
Cookers are on at meal times. If a disaster
strikes when everyone is cooking, the risk of
fires is greatly increased.
Sleeping people are not aware of what is
happening around them; they may not hear of
feel the warnings that come before a disaster.
taken to wearing a "disaster hood" which is
designed to protect the head from falling bricks
and debris if another earthquake was to strike
Quotes from victims of Japan’s
earthquake and tsunami
“My home is burning. I can’t go back there. It’s
too dangerous. I’m staying with a friend but it’s
though. We have no electricity, gas or water.
We can’t bathe. There are huge queues outside
the shops and nothing to buy inside. We have
no idea when our lifelines will return. It’s
terrible, terrible.”
Emiko Mimura, Japanese evacuee, island of
Oshima, Japan
“I’m hungry but what I
most want is furniture,
like a bed and a TV.”
Yuto Hariyu, 15, Miyagi
prefecture, Japan
“It’s terrifying. We have been hit by disasters and now
we are being threatened by something we can’t even
see. Any one of these dangers would be bad, but to be
hit by three in a row is beyond imagination”
Masakai Ohata, Kenssennuma City, Japan after the
explosions at Fukushima nuclear power plant, following
the earthquake and tsunami
Even airplanes have been found amongst the debris from the devastating tsunami - the
force of the water just swept away everything in its way!
Rex
An aerial view of Minamisanriku - one of the devastated coastal areas of northern Japan.
The prime minister of Japan has said the country faces its biggest crisis since the
A woman and her dog walk among the debris.
Lesson Resources
Earthquake hits Japan, a Learnewsdesk
story:
Fleeing Congo
Volcanic Threat in the Congo
After Japan – after the quake and tsunami,
a Learnnewsdesk story,
Japan earthquake and tsunami - in pictures
Map of Japan Earthquake
Lesson on Earthquakes – with photographs
and animation downloads
Richter Scale for Measuring Earthquakes
Building Volcanoes (with downloadable
animations on tectonic plates and
earthquake zones)
Physical and Human History of Japan
Gujarat Earthquake in 2001
Mount St. Helens Volcanic Eruption
Earthquake Eyewitness Report
Video Clips
We Lost Everything
Rescue Story
From NGOs
Red Cross – exploring loss of life, damage
and personal suffering, and the dignity of
those who survived Japan’s earthquake and
tsunami
Haiti Earthquake 2010 - Powerpoint
presentation from ActionAid
Pakistan Floods 2010 – PowerPoint
presentation from Action Aid
Pakistan Flood - lesson ideas to go with
Powerpoint