EarthquakesCharacteristics and Spatial Extent

IB Geography

Focus on: Their spatial extent, predictability, frequency, magnitude, duration, speed of onset and effects.

Global Tectonic Plate Map

• Describe the global distribution of earthquakes that have occurred in the last 7 days? [You could get an exam question like this based upon a given map!]

Mag 5+ since 1980-1990

Look at the global distribution of earthquakes with a magnitude 5 orgreater that have occurred between 1980-90. Is there any difference between theobserved distribution and the distribution of earthquakes that have occurred inthe last 7 days?

Task 2

The following are elements of an earthquake hazard: • Time of earthquake • Date of earthquake • Exact location of epicentre • Fault upon which the quake occurs • The magnitude of the earthquake • The economic impact of the earthquake • The death toll of the earthquake For each of the elements explain how predictable it is.

Task 3

• Read the BBC article and highlight the following in different colours:

• Locations • Dates • Numbers/Values • Any prediction • Any basis upon which a prediction is made • Any issues with earthquake prediction

• Something to think about ... earthquake frequency • Are earthquakes becoming more common? Are there any

patterns in the two illustration above?

Average Frequency

Magnitude Average Annually

8 and higher 1 ¹

7 - 7.9 17 ²

6 - 6.9 134 ²

5 - 5.9 1319 ²

4 - 4.9 13,000

(estimated)

3 - 3.9 130,000

(estimated)

2 - 2.9 1,300,000

(estimated)

¹ Based on observations since 1900. ² Based on observations since 1990.

Essay Question

• Essay Question (10)

• Evaluate the statement:

"There were more deaths from earthquakes in the last decade than the one before so earthquakes are becoming more common."

Magnitude

• Produce notes on the following three scales of magnitude used to measure earthquakes: Richter Scale, Moment Magnitude Scale and the Modified Mercalli Scale.

Alaska 1964 – 9.2

Asia 20049.3

Chile 1960 9.5

Power of resultant tsunami