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

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1
Q

What force causes earthquakes to occur?

A

Friction

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2
Q

How does friction result in an earthquake?

A

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.

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3
Q

What is released during an earthquake?

A

Energy is released as seismic waves

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4
Q

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

A

Focus

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5
Q

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

A

Epicentre

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6
Q

What is the plane along where the plates move called?

A

Fault plane

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7
Q

What depths do earthquakes with a shallow focus occur at?

A

70km or less

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8
Q

What depths do earthquakes with an intermediate focus occur at?

A

70-300km

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9
Q

What depths do earthquakes with a deep focus occur at?

A

300km+

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10
Q

What is the difference between body and surface waves?

A

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

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11
Q

What are two types of body seismic wave?

A

Primary and secondary waves

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12
Q

What are two types of surface seismic waves?

A

Rayleigh and love waves

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13
Q

What are the characteristics of primary waves?

A

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

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14
Q

What are the characteristics of a secondary wave?

A

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

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15
Q

What are the characteristics of love waves?

A

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

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16
Q

What is soil liquefaction?

A

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.

17
Q

Why do earthquakes result in landslides/avalanches?

A

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.

18
Q

How can earthquakes trigger tsunamis?

A

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.

19
Q

What is the difference between a hazard and a disaster?

A

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

20
Q

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

A

10 or more deaths

100 or more people affected

US $1 million in economic losses

21
Q

What is the Degg Model?

A

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.

22
Q

What economic factors can impact on community vulnerability?

A

Level of development, level of technology, level of education

23
Q

What political factors can impact on community vulnerability?

A

Quality of governance

24
Q

What social factors can impact on community vulnerability?

A

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

25
Q

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

A

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

26
Q

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

A

Root cause

Dynamic pressure

Unsafe conditions