Restless Earth Revision

Revise the topicPractice exam technique

Draw

Get into groups of four and number yourselves.

Draw your plate boundary:1. destructive2. collision3. constructive 4. conservative

2 minutes

Practice drawing these diagrams.

Use them in the exam.

Diagrams

• Four plate boundaries• Convection currents• Shield and composite/strato-

volcanoes

• Structure of Earth (probably won’t be asked to draw this one; need to be able to interpret it)

Review and Rate

• Read the summary of the topic. • Rate each section: how confident do

you feel with each part?

The Earth’s Structure

Earth’s interior has a layered structure, with different composition and physical properties.Interpreting a cross-section of the Earth, with details (temperature, density, composition, physical state) of layered structure (including the asthenosphere)

Different types of crust.

OCEANIC

This is heavy (density of 3.0), made ofMinerals rich in Iron and MagnesiumIs about 6-10 km thick on average and isusually under 200 million years old.

CONTINENTAL

This is lighter (density of 2.6), made ofminerals rich in silica and aluminium,is about 30-70km thick and is mainlyover 1500 million years old.

Contrast continental and oceanic crust.

Convection Currents

Solid

Crust

Convection cell in the

mantle

Plumes of heat rise in the mantle

Convection in the liquid outer core

Earth’s Tectonic Plates and their Boundaries

Mapping the distribution of the three plate margin types, and naming major plates.

or

Types of Volcano

A composite or stratovolcano

e.g. Mount Pinatubo, Philippines

A shield volcano

e.g. Mauna Loa, Hawaii

Very hot, runny, basaltic lava.

Eruptions rarely violent.

Thick, viscous, andesitic lava.

Explosive eruptions.

Earthquake Hazards

Contrasting earthquake effects in named locations Impacts on property versus people.

Loma Prieta earthquake, USA• Date: Tuesday 17 October

1989, at 17.04• Magnitude: 6.9 on the

Richter Scale • Epicentre: in a

mountainous part of Santa Cruz County, 90 km south-east of San Francisco

• Death toll: 63• Injured: 3,757• Homeless: 12,000• Property cost: $10 billion

Kashmir, Pakistan• Date: Saturday 8 October

2005• Magnitude: 7.6 on the

Richter Scale• Epicentre: Muzaffarabad,

the capital of Pakistani-administered Kashmir

• Death toll: 75,000• Injured: 75,000• Homeless: 2.8 million• Property cost: $440 million

Impacts worst on property in developed countries.

Impacts worst on people in developing countries.

Contrasting economic and social volcanic hazard impacts

Mount St Helens, USA• Date: Sunday 18th May

1980 at 8.33 am.• Magnitude: 5 on the

Volcanic Explosivity Index 5 (paroxysmal).

• Homes destroyed: 200• Death toll: 61 (most as a

result of poisonous gases which accompanied the blast).

• Evacuated: 2,000 people• Property cost: $1.1 billion.

Mount Nyiragongo, DR Congo• Date: 17th January 2002.• Magnitude: Gentle; 1 on

the Volcanic Explosivity Index (VEI).

• Homes destroyed: 12,500• Death toll: 100 (mostly

from poisonous gas and getting trapped in lava).

• Evacuated: 400,000• Lava: hot, runny, basaltic• Homeless: 120,000

Economic impacts worsein developed countries.

Social impacts worsein developing countries.

Predicting Earthquakes• Earthquakes are not as easy to predict as

volcanic eruptions. However, there are still some ways of monitoring the chances of an earthquake:

• Laser beams can be used to detect plate movement.

• A seismometer is used to pick up the vibrations in the Earth's crust. An increase in vibrations may indicate a possible earthquake.

• Radon gas escapes from cracks in the Earth's crust. Levels of radon gas can be monitored - a sudden increase may suggest an earthquake.

Preparing for Earthquakes• People living in earthquake zones need to know

what they should do in the event of a quake. Training people my involve holding earthquake drills and educating people via TV or radio.

• People may put together emergency kits and store them in their homes. An emergency kit may include first-aid items, blankets and tinned food.

• Earthquake proof buildings have been constructed in many major cities, eg The Transamerica Pyramid in San Francisco. Buildings such as this are designed to absorb the energy of an earthquake and to withstand the movement of the Earth.

• Roads and bridges can also be designed to withstand the power of earthquakes.

Earthquake-proof building design

Developed country

Developing country

Predicting Volcanic Eruptions

Warning signs Monitoring techniques

Hundreds of small earthquakes are caused as magma rises up through cracks in the Earth's crust.

Seismometers are used to detect earthquakes.

Temperatures around the volcano rise as activity increases.

Thermal imaging techniques and satellite cameras can be used to detect heat around a volcano.

When a volcano is close to erupting it starts to release gases. The higher the sulfur content of these gases, the closer the volcano is to erupting.

Gas samples may be taken and chemical sensors used to measure sulphur levels.

Predicting and Preparing for Volcanic Eruptions

Preparing for Volcanic Eruptions

• Creating an exclusion zone around the volcano.

• Being ready and able to evacuate residents.

• Having an emergency supply of basic provisions, such as food.

• Funds need to be available to deal with the emergency and a good communication system needs to be in place.

Haiti, 2010

Impacts Response Problems

Death toll: 200,000 (estimated)Homeless: 1.5 million (estimated)Tens of thousands without food, water and medical suppliesPort-au-Prince port badly damaged

US took control of Port-au-Prince airportUN World Food Programme increased food aid to survivors, e.g. 2 million meals delivered on one dayUS carried out air drops

The Haitian authorities were not prepared for the earthquakePort-au-Prince airport has limited capacityLack of fuel

Glossary

• You need to be familiar with these words so that you can:– understand what questions mean (easier)– define them (harder)

• Use the glossary sheet as a check list. Tick them off once when you when you understand them and again when you can define them.

• Concentrate at first on the terms in bold.

Exam question

(a) Identify one advantage and one disadvantage that Sakurajima has brought to

Japan. (2)

(b) Explain one reason way in which the impact of a volcanic eruption might be different in a less

developed country. (2)

• More deaths/greater impacts on people. Accept other reasonable suggestions.

• Explanation:• People more likely to live in risky locations• Can’t afford safe, well-built houses so buildings

often collapse• Communications poor, so warning and evacuation

may not happen (so effectively)• Poverty• Slow/inadequate relief effort may lead to lack of

shelter, clean water and food. Disease may spread• Governments don’t have the money or resources

to provide aid

(c) Using examples, explain how eruptions can be predicted. (4)

(c) Using examples, explain how eruptions can be predicted. (4)

Warning signs Monitoring techniques

Hundreds of small earthquakes are caused as magma rises up through cracks in the Earth's crust.

Seismometers are used to detect earthquakes.

Temperatures around the volcano rise as activity increases.

Thermal imaging techniques and satellite cameras can be used to detect heat around a volcano.

When a volcano is close to erupting it starts to release gases. The higher the sulfur content of these gases, the closer the volcano is to erupting.

Gas samples may be taken and chemical sensors used to measure sulphur levels.