Deck 3 - Tectonics: Earthquake hazards and factors impacting risk and vulnerability

Question 1

What force causes earthquakes to occur?

Answer 1

Friction

Question 2

How does friction result in an earthquake?

Answer 2

Friction causes tectonic plates to slow or stop in their movement past each other leading to the build up of pressure. When the friction is overcome, the pressure is released as an earthquake.

Question 3

What is released during an earthquake?

Answer 3

Energy is released as seismic waves

Question 4

What is the point in the ground where an earthquake begins called?

Answer 4

Focus

Question 5

What is the point on the surface directly above where an earthquake begins called?

Answer 5

Epicentre

Question 6

What is the plane along where the plates move called?

Answer 6

Fault plane

Question 7

What depths do earthquakes with a shallow focus occur at?

Answer 7

70km or less

Question 8

What depths do earthquakes with an intermediate focus occur at?

Answer 8

70-300km

Question 9

What depths do earthquakes with a deep focus occur at?

Answer 9

300km+

Question 10

What is the difference between body and surface waves?

Answer 10

Body originate and travel within Earth’s whereas surface waves form and travel on the surface

Question 11

What are two types of body seismic wave?

Answer 11

Primary and secondary waves

Question 12

What are two types of surface seismic waves?

Answer 12

Rayleigh and love waves

Question 13

What are the characteristics of primary waves?

Answer 13

Travels the fastest, smallest amplitude, compressional wave that cause the Earth to move horizontally in the same direction as the wave is travelling

Question 14

What are the characteristics of a secondary wave?

Answer 14

Travels the second fastest, have a higher amplitude than primary waves and produce vertical movement as the ground moves perpendicular to the direction the wave is travelling

Question 15

What are the characteristics of love waves?

Answer 15

Travels more slowly and has a large amplitude. Love waves move the ground horizontally back and forth as they move forward

Question 16

What is soil liquefaction?

Answer 16

Soil liquefaction is a phenomenon that occurs when soil loses its strength and stiffness and behaves like a liquid during an earthquake due to intense ground shaking.

Question 17

Why do earthquakes result in landslides/avalanches?

Answer 17

In areas of steep relief the ground is make unstable due to the shaking from the earthquake. This can result in the downward movement of the land or trigger an avalanche in a mountainous area.

Question 18

How can earthquakes trigger tsunamis?

Answer 18

Earthquakes that occur underwater can cause the ground to deform causing the upward displacement of water. This leads to a large tidal wave that travels in every direction away from the earthquake and is called a tsunami.

Question 19

What is the difference between a hazard and a disaster?

Answer 19

A hazard is an event that has the potential to cause harm, whereas a disaster has had a significant impact on people, animals or infrastructure

Question 20

What numerical criteria can be used as threshold for determining whether an event is a disaster?

Answer 20

10 or more deaths

100 or more people affected

US $1 million in economic losses

Question 21

What is the Degg Model?

Answer 21

The Degg Model shows the intersection between a hazardous natural event and a vulnerable population which experiences human and/or economic loss, to create a disaster.

Question 22

What economic factors can impact on community vulnerability?

Answer 22

Level of development, level of technology, level of education

Question 23

What political factors can impact on community vulnerability?

Answer 23

Quality of governance

Question 24

What social factors can impact on community vulnerability?

Answer 24

Population density, population profile (age/gender), rural/urban population, time of day, degree of isolation

Question 25

What does the Pressure And Release (PAR) model show?

Answer 25

The PAR model is used to analyse factors which cause a population to be vulnerable to a hazard

Question 26

What are the three elements to the progression of vulnerability in the PAR model?

Answer 26

Root cause

Dynamic pressure

Unsafe conditions