3.1.5.4 Seismic hazards

Question 1

Define tsunamis

Answer 1

• giant sea wave caused by shallow focus earthquakes
• long wavelength
• travel quickly
• large wave height

Question 2

Define liquefaction

Answer 2

When violently shaken soils with high water content lose their mechanical strength and become fluid

Question 3

Define shockwaves and seismic waves

Answer 3

Two main types of seismic waves:
- P waves (6km per hour, through solids and liquids)
- S waves (3km per hour, and cannot travel through liquid)

Question 4

Define landslides

Answer 4

A slope failure as a result of the ground shaking

Question 5

Describe the spatial distribution of earthquake

Answer 5

• majority occur on plate boundaries
• few can occur with the reactivation of old fault lines
• human activity can induce earthquakes (Taylor Swift concert induced a magnitude 2)

Question 6

Name the 3 methods of measuring earthquakes

Answer 6

• Richter scale (logarithmic 1-10)
• moment magnitude scale (measures energy release)
• Mercalli scale (measures intensity by its impact upon people)

Question 7

How can you predict earthquakes

Answer 7

It is very difficult but you can monitor:
- crustal movement
- strange animal behaviour

Question 8

How can you protect against earthquakes (4)

Answer 8

• ensure safety drills are well practiced
• building hazard resistant structures
• land use planning
• fire prevention (smart meters can cut off gas under shaking)

Question 9

When was the Haiti earthquake

Answer 9

2010

Question 10

Where was the epicentre of the Haiti earthquake

Answer 10

24km south-west of capital Port-au-Prince

Question 11

How deep was the focus of the Haiti earthquake

Answer 11

13km

Question 12

What percentage of the population of Haiti live below the poverty line

Answer 12

40%

Question 13

Primary effects of the Haiti earthquake (social x3)

Answer 13

• 230,000 dead
• 1.5 million people homeless
• 50% of buildings destroyed, including 80% of schools (due to liquifaction)

Question 14

What was the magnitude of the Haiti earthquake

Answer 14

7.0

Question 15

Secondary effects of the Haiti earthquake

Answer 15

• aftershocks of 6.1 magnitude
• with the 25% of civil servants dying and the destruction of official buildings, the government was crippled
• city became lawless
• cholera outbreaks

Question 16

Immediate responses of the Haiti earthquake (governmental, social x2)

Answer 16

• 16,000 US troops restored law and order
• bottled water and purification tablets for 250,000 people
• over 1,100 camps to shelter 1.5 million people

Question 17

Long term responses of the Haiti earthquake (econ, social, econ)

Answer 17

• $11.5 billion in aid
• unemployed people paid to reconstruct key buildings
• economic activities centred away from Port-au-Prince

Question 18

When was the Tohoku earthquake, Japan

Answer 18

2011

Question 19

How many earthquakes does Japan have in a year

Answer 19

1500

Question 20

What was the magnitude of the Tohoku earthquake

Answer 20

9.0

Question 21

How long after the earthquake did the first tsunami hit

Answer 21

30 minutes

Question 22

Primary effects of the Tohoku earthquake (3)

Answer 22

• limited damage from the earthquake due to earthquake proof buildings
• 18,000 dead or missing due to the tsunami
• warning system saved many lives

Question 23

Secondary effects of the Tohoku earthquake (3, social)

Answer 23

• 500,000 homeless
• over 700 aftershocks
• explosions and radiation leaks at Fukushima Daiichi nuclear power plant
• fears of nuclear disaster caused panic seling

Question 24

Immediate responses of the Tohoku earthquake (3, UK)

Answer 24

• 100,000 soldiers mobilised to establish order
• UK sent 63 search and rescue specialists
• an exclusion zone around Fukushima Daiichi and then the government shut down nuclear plants

Question 25

Long-term effects of the Tohoku earthquake (future, social, economic)

Answer 25

• future contingency plans against tsunamis (new warning system in 2013)
• 100,000 residents not returned home 5 years later
• $300bn in damages