1. Year 9 Revision Winter exam

2. RESTLESS EARTH

3. Structure of the Earth The Earth is made up of 3 main layers: – Core – Mantle – Crust Inner core Outer core Mantle Crust

4. World Plates

5. What are earthquakes and where do they occur? Earthquakes are vibrations caused by movements at plate margins and at fault lines (cracks in the earth’s surface). They can occur at all 4 major plate boundaries but the most severe earthquakes are normally found at CONSERVATIVE and DESTRUCTIVE plate margins. CONSERVATIVE DESTRUCTIVE

6. Why do earthquakes happen?

7. How can we measure earthquakes? The largest earthquake ever recorded was in Chile. It measured 8.9 on the Richter Scale. This measures the magnitude of a tremor (how powerful it is) using an instrument called a seismograph. On the Richter Scale, magnitude is expressed in whole numbers and fractions. It is a logarithmic scale which means that a size ‘6’ on the Richter Scale is 10 times larger than a size ’5’ and 100 times larger than a size ‘4’. 1 2 3 4 6 5 9 8 7 10 Richter Scale The Richter Scale

8. Mercalli Scale This measures how much damage is caused by the earthquake based on observations. It is measured on a scale between I and XII. Mercalli Scale

9. Epicentre and focus

10. predict planprotect 1. predict water levels can rise in wells and lakes because of cracks in the rock foreshocks before the main quake can be detected by a seismometer animals can act strangely before the earthquake a tiltmeter can check any movement within the rocks How can we limit earthquake damage?

11. 2. plan What should people pack in their emergency kit? make an emergency plan organize regular ‘earthquake practices’ for offices and schools advise people to plan for an earthquake (eg tell them to turn off the gas, find a ‘safe’ place in their homes, pack an emergency kit) enforce regulations to make some buildings earthquake proof Design a poster reminding people what to do in an earthquake. How can we limit earthquake damage?

12. Impacts PrimarySecondary

13. TSUNAMI What do you know?

14. What caused the tsunami?

15. Volcanic bombs, ash, lava, gases Magma chamber Parasitic cone Crater Main vent VOLCANOES

16. At destructive plate boundaries the lava is viscous (thick like treacle) and it cannot flow very far from the volcano’s vent. This makes the volcano steep sided. At constructive plate boundaries the lava is runny and it can flow far away from the volcano’s vent. This makes the volcano gentle sided.

17. Active volcano – liable to erupt e.g. Mt Etna. Dormant (sleeping) volcano – a volcano which has not erupted for many years. For example, Mt Pinatubo erupted in 1991 after 500 years of dormancy. Extinct volcano – a volcano which has not erupted for many thousands or millions of years e.g. Edinburgh. However, it is often very difficult to tell whether a volcano will erupt again…El Chichon, Mexico erupted in 1982 after being dormant for approximately 1200 years! Do all volcanoes erupt?

18. Mt St Helens – the eruption

19. This lava is weathered (broken down) to form a fertile soil, Tourists are attracted to areas of volcanic activity. Geothermal energy (heat from the earth) can be produced in many volcanic areas. Can you think of any other reasons? Why do people live in volcanic areas?

20. EXTREME WEATHER

21. HURRICANES

22. 22 How do hurricanes form?

23. 23 Hurricane Katrina hit New Orleans on the morning of the 29 th August 2005 bringing with it terrible destruction. Winds of over 250 kilometres per hour were recorded as Katrina hit the coast, causing a storm surge 8.5 metres high. New Orleans Hurricane Katrina

24. 24 80% of the city was flooded and over a million homes were left without electricity. Over 1,800 deaths were caused by the storm, around 700 of them in New Orleans. In some areas the flood level rose to over six metres. Those that had decided to stay in their homes had to either find high ground and await rescue or risk swimming and wading through polluted floodwater. Effects of Hurricane Katrina

25. TORNADOES – do you know the answers to these questions? 1.Why do they happen? 2.What states do you find in Tornado Alley? 3.What is Tornado Watch? 4.What is Tornado Warning? 5.What is the Fujita scale?