1. From the spec
Today we will investigate –
How do plate tectonics shape our world?
- the causes and features associated with earthquakes
- how technological developments can have a positive impact on mitigation
Resource
Text book page 28– 31 and 38
Main skill
Visual Literacy: Describing and explaining the global pattern of earthquakes.

2. TITLE: Earthquakes - features and management
Aims:
to understand the features associated with earthquake activity
to consider the strategies used to manage earthquake risk
Challenge: to explain how technological developments can have a positive effect on earthquake mitigation.

3. What is an earthquake?
Earthquakes are vibrations (shock waves) caused by the movement of the Earth’s plates. The plates are moving because heat from the mantle creates convection currents.
Earthquakes can occur at all types of plate boundaries but the most severe earthquakes are found at conservative and destructive plate boundaries.
conservative
destructive

4. Where do earthquakes occur?
- 80% of all earthquakes occur around the Pacific rim (the Ring of Fire)
15% occur in the Mediterranean-Asiatic belt
5% occur in the interiors of plates
Over 150,000 quakes strong enough to be felt are recorded each year
When describing the distribution of earthquakes refer to - region and continents by name; mention uneven pattern,; concentrated in zones along plate boundaries.
You don’t need to explain the pattern unless the question asks you to explain.

5. The stress builds up. A sudden release is an earthquake.
What causes earthquakes?
Earthquakes occur because the plates are moving and this movement creates friction. The plates do not move smoothly (think of Velcro).
The stress builds up. A sudden release is an earthquake.
The point of release in the crust is called the focus. If the focus is shallow (close to the surface) the shock waves, called seismic waves, will have more impact.
The point on the surface directly above the focus is the epicentre – generally the place of greatest shaking.

6. The primary effects of earthquakes
Liquefaction – water in the ground rising and causing buildings to sink.
Tsunami – giant waves caused by an earthquake at sea
Damage to property. Collapse of buildings, roads and railways
Death and injuries.
Fires and gas explosions as electricity cables and gas pipes fracture.

7. The secondary effects of earthquakes (longer term consequences)
Homelessness – leading to illness and death.
Spread of diseases. Water is contaminated as sewage and clean water pipes fracture.
Communications fail (phone and computer links cut)
Rising food prices and shortages. Supplies in shops are affected.
Long term debt – to people and the country.
Job losses – businesses suffer and struggle to recover.
Increased insurance costs (in ACs)

8. Measuring earthquakes: The Richter Scale
Developed in 1935 by Charles Richter of the California Institute of Technology,
The Richter scale measures the strength or magnitude (energy) of an earthquake.
It is a logarithmic scale. So, for example, an earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger than one that measures 4.0.

9. The Richter Scale Increasing energy 9 Catastrophe, total destruction 87
Disaster, many buildings destroyed 6
Damages buildings 5
Strong shake, may cause windows to break 4
A moderate shake felt by people moving about 3
A slight shake 2
30 times more energy but will only noticed by sensitive people 1
You would not notice this 9

10. The strength or magnitude of an earthquake can be measured with a seismometer - which records the vibrations within the Earth.
A seismograph is the graph that a seismometer draws - don't get these muddled up!
Example - a rotating drum records a red line on a sheet of paper. If the earth moves, the the pen will wobble and record a squiggle!

11. Measuring earthquakes: The Mercalli Scale
The Mercalli scale is not the same as the Richter scale.
The Mercalli scale measures the impact of an earthquake (e.g. deaths & damage).
For example a powerful earthquake might have a low impact if –
Population density e.g. the area has few people
Geology. e.g. The rock type is hard, strong rock
Building quality. e.g. The buildings are well built and strong.
Time of day. e.g. if the earthquake happens in the middle of the night there will be few people in town centres

12. Earthquake hazards. What actions can be taken to mitigate the risks?

13. Earthquakes cannot be prevented from happening
Earthquakes cannot be prevented from happening. But a variety of actions can be taken to mitigate (lessen) their impact.
These actions include –
prediction
building design
education
emergency services and planning

14. 1) Prediction. Technological developments are making predictions more reliable. .
Monitoring water levels – which can rise in wells and lakes prior to an earthquake
a tiltmeter can monitor any movement within the rocks
Scientists study animal behaviour – for any strange actions which may precede an earthquake
a seismometer can monitor any foreshocks before the main quake.

15. 2 Building design
Which shaped building would be more ‘earthquake resistant’?

16. This is San Francisco in the USA.
San Francisco is near the San Andreas Fault and therefore the city experiences earthquakes.
This skyscraper has been built to be ‘earthquake resistant’.
Its wide base lowers the centre of gravity of the building and makes it more stable.

17. Engineering structures for earthquakes
Clip:

18. 3) Education. Ensure people know -
What should I do?
Where is the safest place?
What should I have in my emergency kit?
Preparing for earthquakes

19. 4 Land use planning and zoning.
GIS can be used to identify high risk areas and the likelihood of earthquakes.
Using GIS, maps of earthquake risk areas can be used to ensure - building codes are relevant; emergency services are equipped, people, schools, businesses have plans in place for any emergency.

20. These are the deadliest earthquakes since 1900. What do you notice?
Country
Region
Date
Death toll
magnitude
China – N.E
Tangshan
28 July 1976
250,000
7.5
Tsunami - SE Asia
S.E Asia
26 Dec 2004
230,000
9.2
China - central
Haiyuan county
16 Dec 1920
200,000
7.8
Haiti
Caribbean
13 Jan 2010
7.0
China – SW
Sichuan
12 May 2008
87,000
Pakistan
Kashmir region
8 Oct 2005
73,000
7.6
Peru
Yungay, Andes
31 May 1970
66,000
7.9
Iran
Gilan region
21 June 1990
40,000
7.2
Bam
26 Dec 2003
26,000
6.3
Turkey / Armenia
NW Armenia
7 Dec 1988
25,000
6.9
Turkey
Izmit
17 Aug 1999
17,000
7.4
The correlation between magnitude and death toll is weak. Why is that?
All the deadliest earthquakes are in LIDCs or EDCs. Don’t ACs have earthquakes?

21. Do you agree with this statement?
Advanced Countries (ACs) also have earthquakes, but the impacts will be very different.
A collapsing building will kill you whether you are in a rich country (AC) or a poor country (LIDC / EDC)
True but a person in a rich country is much more likely to survive an earthquake because…
‘The rich lose their money, the poor lose their lives’.
Do you agree with this statement?

22. Target grades 5 & 6 Target grades 7+
HW: Choose any two questions from the appropriate target grade column.
Each is worth 6 marks.
Expected length 2/3 page each.
Target grades 5 & 6
Target grades 7+
Q. Explain, in detail, the processes that cause an earthquake.
Q. Explain why some parts of the world are more vulnerable to earthquakes than other parts
Q. Suggest two examples of information that may be observed and recorded by earthquake scientists. Explain how each one could be used to predict an earthquake.
Q. Explain how technological developments can have a positive effect on the mitigation of earthquake hazards.
Q. Explain why there is a weak correlation between the magnitude of an earthquake and the resulting death toll.
Q. Explain why the risk of death from an earthquake is much lower in an Advanced country.