EQ2 Lesson 14 - Measuring Scales (Earthquakes)

Question 1

What is the nature of both the Richter and Moment Magnitude scale?

Answer 1

Logarithmic
Increases by factor of 10 per value

Question 2

Which 2 other scales are regularly used to measure earthquakes?

Answer 2

Moment Magnitude
Mercalli

Question 3

Which factors does the Moment magnitude scale observe?

Answer 3

Energy released by all shockwaves
Area of rupture + movement
Resistance of affected rocks

Question 4

What is the purpose of the Moment Magnitude scale?

Answer 4

Determine the magnitude of an earthquake

Question 5

Which scale is supposedly the most accurate?

Answer 5

Moment Magnitude

Question 6

How does the moment magnitude scale express magnitude?

Answer 6

Logarithmic numerical scale
Whole numbers + decimals

Question 7

What is the largest earthquake ever recorded by the moment magnitude scale?

Answer 7

9.5, Chile 1960

Question 8

What is the highest magnitude the moment magnitude scale is able to record?

Answer 8

No upper limit

Question 9

What are earthquakes <2.0 in magnitude referred to as + how are they recorded?

Answer 9

Micro-earthquakes
Local seismographs

Question 10

Why may the Moment Magnitude scale be misleading?

Answer 10

Only records magnitude - Magnitude doesn’t dictate deaths
High magnitude event in an isolated area will present less threat to life than a moderate earthquake in a densely populated area.

Question 11

What are the advantages of the Moment Magnitude scale?

Answer 11

No upper limit
Takes most accurate record of magnitude

Question 12

What are the disadvantages of the Moment Magnitude scale?

Answer 12

Doesn’t consider damage
Can be misleading

Question 13

What does the Mercalli scale monitor?

Answer 13

Earthquake intensity

Question 14

What does the scale itself consist of?

Answer 14

Quantitative rankings: 1-12 (I - XII)
Qualitative descriptions: Instrumental(I) - Catastrophic (XII)

Question 15

What do the Mercalli scale’s descriptions focus on?

Answer 15

What people involved feel
Observable damage to buildings

Question 16

Why might the Mercalli scale be difficult to interpret?

Answer 16

People’s experiences are subjective
One person’s interpretation of E.g., ‘vibrations caused by heavy traffic’ may be different to another’s

Question 17

How could local conditions have an impact upon the Mercalli scale’s correlation between intensity + magnitude?

Answer 17

Correlation may be modified
Low magnitude but weak geology/shallow focus may seem very intense

Question 18

What are the advantages of the Mercalli scale?

Answer 18

Represents urban populations well
Not reliant on logarithmics

Question 19

What are the disadvantages of the Mercalli scale?

Answer 19

Definitions depend on people’s own experiences
Local conditions may distort accuracy
Loses value outside of urban settlements