Leaving Certificate slides on Earthquakes - causes, areas, features, measurement, effects, case studies

2. 3 Key Terms
FOCUS – starting point of earthquake, deep underground
EPICENTRE – Point on surface, directly above focus.
Earthquake is strongest here
FAULT – Dividing line between 2 plates

7. 2013 HL

8. Earthquake Depths
Shallow – 70K or less below ground. Contact between
Continental Plates. MOST DESTRUCTIVE.
Intermediate – 70 to 300K depth. Oceanic to Continental
Plate Contact
Deep – 300k+. Least destructive.
Why?

18. 2013 HL Short Question

19. What are the effects of Earthquakes?
 Page 24 Text

25. Haiti Earthquake
• Cities in Haiti had large Shanty towns, these were
badly damaged
• Cholera spread rapidly after the earthquake
• Haiti’s large debts meant that the country had no
money to deal with earthquake damage
• Earthquake hit just 25 KM from capital city – v little
warning

26. 2008 Ordinary Level Question

27. Page 30 Text

29. Predicting Earthquakes
• Examining Seismograph activity – lots of small
quakes show that a major quake is on the way
• Measuring Crustal Stress – drilling deep holes
and measuring rock pressure
• Lasers – used to measure ground movement
• Radon Gas – rocks under stress emit more
Changes in oil/water levels in wells – rising
levels = more pressure
• Unusual animal behaviour – some animals are
more sensitive to P-Waves

30. 2013 Higher Level Essay &
marking Scheme

32. • Spring loaded foundations
• Shatterproof Glass in windows
• Flexible joints in buildings – buildings can flex under
pressure
• More supports on each floor
• Furniture and loose items to be secured

37. You are marked on the number of Significant, Relevant
Points you have in your essay. Do not waffle, it only
wastes time.
Diagrams can be used to get SRPs
Key to high marks is to read the question carefully and
underline keywords
“Explain with reference to examples you have studied,
how the theory of plate tectonics helps to explain the
distribution of earthquakes around the world”
Essay writing in Geography

38. “Explain with reference to examples you have studied,
how the theory of plate tectonics helps to explain the
distribution of earthquakes around the world”
Question asks about distribution
In plain English, “Why do earthquakes happen where
they happen”
NOT
“How do earthquakes happen”
Reading the Question

39. Wrong approach
“Earthquakes are caused by rocks slipping past each
other. This causes shockwaves to spread out from the
focus which cause great damage to buildings.
Earthquakes give off P waves, S waves and Surface waves
and surface waves are the most damaging. When an
earthquake happens underwater it can cause a Tsunami
which can cause floods like in Japan etc etc etc............
No mention of Plate Tectonics or of where earthquakes
happen. Just general discussion. No relevance to
question.

40. Right Approach
“The theory of Plate Tectonics tells us that the Earth’s crust is
divided into several plates. It also tells us tells us that plates
can collide (destructive boundary) or scrape past each other
(constructive boundary). When this happens, Earthquakes can
occur. The Plates are moving because of convection currents
in the Earth’s mantle which drag the plates around. Thus
earthquakes are unlikely to occur in areas like Ireland which
are far from plate boundaries. Areas like California are on the
boundary of two plates (North American and Pacific) and
therefore experience frequent Earthquakes .........”