P1 The Earth in the Universe • IP1.8

LO:consider the actions that governments can take to reduce

the harmful effects of natural disasters

• Name the 3 different types of plate boundary.

• What happens at each of them?

P1 The Earth in the Universe • IP1.8

Geohazards that might affect us

P1 The Earth in the Universe • IP1.8

WHAT IS A

GEOHAZARD?

P1 The Earth in the Universe • IP1.8

What Earth processes can affect us?

• landslide

• flood

• the effects of a

volcanic eruption

• earthquake

• tsunami

Geohazards that might

affect us today are:

P1 The Earth in the Universe • IP1.8

Landslide

• slopes are steep

• rocks are weak or

fractured

• erosion undermines a

slope

• water builds up in the

ground

• earthquakes strike

• human activities are

poorly planned

Landslides are triggered

where:

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But, even on flat ground:

• Foundations on weak

rock can subside.

• Old mine workings can

collapse.

• Soluble rocks below

ground can dissolve.

Collapse

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Floods occur:

• in low-lying areas

• after a storm upstream

• after many wet days

upstream

• if snow melts quickly

• when rivers overflow

• on stormy coasts at

high tide

• if dams burst

Flood

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Flood mayhem

• There are thick mud

and silt deposits.

• Sewers overflow.

• Large objects are

swept away:

bridges, houses,

embankments, cars.

• There is electrical

danger.

It’s not just the amount of

water in a flood:

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Eruption afar

• a volcanic winter – from ash and sulfur dioxide in the atmosphere

• drought over great regions

• widespread crop failure in summer, bitter cold in winter

• the whole Earth cooled

• fantastic sunsets

There are no active volcanoes in the UK, but a major eruption

elsewhere may cause:

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Eruption on your doorstep

Catastrophic effects include:

• blast: 30 km+

– everything is destroyed

• glowing cloud

– a red-hot current of ash

– travelling with speeds of 100 km/h+

• lahar

– waterlogged volcanic ash flooding

down valleys

• tsunami

– a great wave in coastal areas

• lava flow

– rarely kills because you can get

out of the way

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• They are not big enough to make

surface waves, so little damage

occurs.

• We can feel seismic waves.

• Recent UK earthquakes:

www.quakes.bgs.ac.uk/recent_events/recent_events.html

• Earthquakes are plotted from

eyewitness accounts.

• If you feel an earthquake, send in

your evidence:

www.quakes.bgs.ac.uk/questionnair

e/EqQuestIntroB.html

Earthquakes in the UK

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Earthquake

In a catastrophic earthquake:

• The ground rises and falls in waves.

• There is total destruction of

non-flexible structures.

• People are killed by falling buildings –

outside is safest.

• There is risk from falling glass and fire

storms.

• There may be a tsunami – a huge

wave in coastal areas.

• Many die afterwards from disease.

• The most recent big earthquake:

earthquake.usgs.gov/eqcenter/

recenteqsww/index.php?

old=world.html

P1 The Earth in the Universe • IP1.8

Tsunami

• can form waves over 40 m high

• can reach speeds of 1000 km/h

• can travel 10 000 km across oceans,

killing thousands in coastal areas

• can trick you, because water first

draws back from the coast – and

then thunders back in

These huge waves produced by

volcanic eruptions, earthquakes, or

submarine landslides:

P1 The Earth in the Universe • IP1.8

Worry? – Us?

• Major eruptions and earthquakes

affect only the active zones of the

Earth.

• They don’t happen in the UK.

• But – could a geohazard happen

here?

• What might its effects be?

P1 The Earth in the Universe • IP1.8

• http://www.brainpop.com/science/earthsystem/naturaldisasters/

• http://www.brainpop.com/science/earthsystem/earthquakes/

• http://www.brainpop.com/science/earthsystem/tsunami/

P1 The Earth in the Universe • IP1.8

Imagine you are in an earthquake...

• Using the worksheet as a guide, write down the effects of the earthquake on you and your family.

P1 The Earth in the Universe • IP1.8

How can the government prepare their countries for a disaster such as

these?

Discuss the methods that we would have to use to protect ourselves.

P1 The Earth in the Universe • IP1.8

Bingo

Volcano

Earthquake

Conservative

Convergent

Divergent

Tectonic

Pangea

Wegener

Fossils

IgneousMetamorphic

PressureHeat

SedimentarySedimentErosion

WeatheringMagma