1. Living in an Active Zone
Revision

2. Cross section of the Earth

3. Structure of the earth Earth is made up of four distinct layers
Crust (oceanic/ Continental)
Mantle
Outer core
Inner core

4. Structure of the earth Crust is broken up piece called tectonic plates
7 large plates and 12 small plates
These plates move because of Convection Currents in the magma
Where two plates meet is a plate margin

5. Why do the plates move?

6. Constructive Plate Margins
Two oceanic plates move away from each other shield volcanoes form creating mid ocean ridges e.g. mid Atlantic ridge.
When two continental plate move apart a rift valleys are formed. Shield volcanoes found here e.g. Iceland

7. Constructive plate boundary

8. Constructive Plate Margins

9. Destructive Plate Margins
Oceanic and continental Crust
Where it involves oceanic and continental crust, the oceanic crust is always subducted below the continental because it is denser.
The subduction of the oceanic crust creates a deep sea trench and earthquakes are formed at the subduction zone.
Fold mountains are created on the continental crust .
The subducted oceanic crust melts in the mantle rising up into the fold mountain to create composite volcanoes
E.g. Mount St Helens

10. Destructive plate boundary

11. Destructive Plate Margins
Oceanic crust only
Destructive plate margins also can involve two oceanic plates
Here island arcs are formed in the oceanic crust
E.g. Montserrat, Caribbean

12. Destructive Plate Margins

13. Types of Volcanoes
Shield Volcanoes found on constructive plate margins. Lava is hot and runny. Not as explosive. Not very high. Very wide base
Composite volcanoes found on destructive plate margins. Thick stick lava. Erupt explosively. Very tall cone shaped.

15. Volcanic hazards
Lava flow
Ash
Lahars
Lava bombs
Pyroclastic flow

16. Volcanic Hazards

17. Earthquakes – Causes
Earthquakes are cause by shock waves travelling through the earth crust
The source of the earthquake is called the focus, the epicentre is the point immediately above it on the surface
Size of an earthquake can be measured by a seismometer along the Richter scale
Tsunamis are a secondary hazard of an earthquake

18. Epicentre
Focus
Seismic waves

19. Earthquakes - Factors Strength of the earthquake
Distance from epicentre
Depth of the focus
Number of people living in an area
Type of rock
Time of day
The extent of preparation

20. Why do people live there?
500 million people live in active zones
Dramatic scenery created attracts tourists, bringing income to an area e.g. Mount Vesuvius, Italy
Lava and ash provide nutrients to the soil, making the land near volcanoes very fertile and good for agriculture. E.g. Mount Etna, Italy
Opportunities to generate electricity using the heat from the earth (geothermal energy) E.g. Iceland
Volcanic rock is a good building stone
Many people cannot afford to Move (LEDCs) E.g. Mount Pinatubo, Philippines
Tectonic hazards are rare and often to affect an area in a persons lifetime E.g. Montserrat volcano had not erupted for 300yrs until recently
Prediction and earthquake resistant building are improving. E.g. Kobe Japan has many earthquake proof buildings
DON’T FORGET YOU NEED TO GIVE EXAMPLES

21. Predicting and preparing - Earthquakes
Laser beams used to detect plate movements
Seismometer used to pick up vibrations
Radon gas – escape from the cracks in the crust before an earthquake – this can be monitored
Preparing
Educating people via TV or in schools what to do
Earthquake drills to prepare
Earthquake proof buildings, designed to absorb the energy of an earthquake and withstand movement

22. Predicting and preparing - Volcanoes
Remote sensing – satellites monitor temperature and gas emissions
Seismometers – measures earthquakes activity that occurs before an eruption
Tiltmeters – monitor changes in the shape of a volcano as it fills with magma
Gas emissions – indicate an increased risk
Ultra sound – to detect movements of magma
Preparing
Exclusion zones created around volcanoes
Authorities must be ready to evacuate
Emergency supplies of basic provisions must be gathered
Good communication systems in place

24. This is an alternative casestudy - Miss Kingdom’s class had two different casestudies (New Zealand and Pakistan). It is up to you which one you lean