Seismic hazards

Question 1

Earthquake

Answer 1

• Shaking vibration of the Earth’s crust = movement of plate tectonics
• Can happen along any plate boundary

Question 2

When do they occur

Answer 2

• Tension is released from inside crust

- Pressure builds when the plates move

Question 3

Focus

Answer 3

• Point inside the crust where pressure is released

Question 4

Epicentre

Answer 4

• Point on the earth’s surface above the focus

Question 5

Seismic waves

Answer 5

• Earthquake energy, spread from the focus

- Strongest at epicentre and lose energy when they travel

Question 6

Distribution

Answer 6

• Occur along every plate boundary
• Long, narrow, uneven belts
• Wider clustered belts
• Dense clustering = Ring of fire

Question 7

Constructive

Answer 7

• Some earthquakes

- Depth = close to surface

Question 8

Destructive

Answer 8

• Majority of earthquakes
• Horizontal spread - widest spread along plate boundary
• Depth = shallow

Question 9

Conservative

Answer 9

• Lots of earthquakes
• Horizontal spread = narrow spread along plate boundary
• Depth = very shallow

Question 10

Intraplate

Answer 10

• Occurs in the interior of tectonic plate = relatively rare

- Don’t know causes - rising magma at hotspots?

Question 11

Interplate

Answer 11

• Occurs at the plate boundary

- More common

Question 12

How are earthquakes measured?

Answer 12

• Seismographs = Seismogram
• Difference in position between the shaking part of the seismograph and the motionless part is what is recorded.
  Size = magnitude
  Effect = intensity

Question 13

Richter scale

Answer 13

• Logarithmic scale
• Measures magnitudes
• Energy relese is proportional to the magnitude

Question 14

Modified mercalli scale

Answer 14

• Intensity of an event and the impact

- 12 point scale

Question 15

Seismic records

Answer 15

• Enable earthquake frequency to be observed - only date back to 1848

Question 16

Forms of seismic hazards

Answer 16

• Earthquakes
• Shockwaves
• Liquefaction
• Landslides

Question 17

Secondary impacts of seismic hazards

Answer 17

• Liquefaction
• Tsunami
• Landslides
• Flooding
• Fires