Seismic hazards

Question 1

Name some human impacts which influence the effects of an earthquake

Answer 1

Population size
Time of day
Poverty
Rural or urban landscape

Question 2

Name some physical impacts which influence the effects of an earthquake

Answer 2

Depth
Magnitude
Distance from epicentre
Local geological conditions

Question 3

Describe the distribution of earthquakes

Answer 3

Occur on all plate boundaries

Question 4

What are the two types of shockwaves?

Answer 4

Primary (P) waves; fastest and reach the surface first

Secondary (S) waves; slower, reach the surface second

Question 5

How are tsunamis formed?

Answer 5

Seismic activity on the ocean floor (e.g. earthquakes or submarine eruptions)

Question 6

How do tsunamis differ from normal ocean waves?

Answer 6

• Wave heigh is initially low (1m) but can rise to 25m when approaching the shore
• Travel between 640 - 960km per hour
• Long wave period, 10 - 60 mins between each wave
• Wavelength between 100 - 1000km

Question 7

How is the magnitude of an earthquake measured?

Answer 7

Richter scale
Scale starts at 0 and each number is 10 times the magnitude of the one previous
Values above 8 disrupted the seismograph, now uses the Moment Magnitude scale to measure the amount of energy released from an earthquake

Question 8

Describe the frequency and regularity of earthquakes:

Answer 8

It’s impossible to accurately predict when or where a seismic even will occur
Scientist can only study which areas are more active than others

Question 9

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Answer 9

Magnitude and depth of the quake 
Distance from the epicentre 
Population density 
Preparedness and education 
Time of day

Question 10

Name some primary impacts of an earthquake:

Answer 10

Immediate death and injury 
Ground shaking 
Buildings collapse, roads destroyed, power lines collapse
Landslides and avalanches 
Liquefaction

Question 11

Name some secondary impacts of an earthquake:

Answer 11

Fires (caused by broken gas pipes and power lines)
Diseases spread from contaminated water 
Emergency services are hindered 
Education suspended
Flooding from blocked rivers

Question 12

Name some long-term impacts of an earthquake:

Answer 12

Disability/illness and reduced life expectancy
Higher unemployment as not all businesses recover
Loss of farmland
Repairs to buildings is costly and could take months to years

Question 13

Give some human and natural causes of seismicity

Answer 13

Human - mining and fracking

Natural - Plate movement