Hazards - Earthquakes Flashcards

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1
Q

What is an earthquake?

A

An intense shaking motion experienced in the surface of the crust due to stress suddenly being released

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2
Q

What is the focus of an earthquake?

A

The point where pressure is released in the crust

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3
Q

What is the epicentre of an earthquake?

A

The point on the surface that experiences maximum ground shaking

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4
Q

What percentage of all earthquake energy released are from shallow focus earthquakes?

A

75%

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5
Q

How deep are shallow focus earthquakes?

A

0-70km

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6
Q

How deep are intermediate focus earthquakes?

A

70-300km deep

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7
Q

How deep are deep focus earthquakes?

A

300-700 km deep

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8
Q

Name 3 cities where seismically active regions coincide with dense populations

A

Islamabad
Istanbul
Lima

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9
Q

What is the richter scale?

A

A logarithmic scale for measuring magnitude of earthquakes

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10
Q

WHat are seismic waves?

A

Shock waves moving through rock

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11
Q

What are the 4 types of seismic wave?

A

Primary
Secondary
Rayleigh
Love

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12
Q

Which seismic waves are body waves?

A

P and S

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13
Q

Which seismic waves are surface waves?

A

R and L

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14
Q

Descibre primary waves

A

Travel through solids and liquids
Fastest - 5.5km/s
Compressional

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15
Q

Describe secondary waves

A

Travel through solids
Slower - 3km/s
Longitudinal

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16
Q

What are the 2 different categories of seismic waves?

A

Surface

Body

17
Q

Order a seismometer feels waves

A

PSLR

18
Q

Which type of waves are the most destructive?

A

Surface waves

19
Q

Describe the motion of Rayleigh waves

A

Rolling motion

20
Q

How do love waves shake the ground?

A

Perpendicular to direction of movement

21
Q

What is the Mercalli scale?

A

A measure of intensity of earthquakes by people giving subjective opinions on how strong the ground was shaking

22
Q

What is a problem with the Richter scale?

A

It hasn’t been as effective on magnitudes of over 6 as energy is lost in the movement of the machine

23
Q

What are the primary impacts of seismic events?

A

Ground shaking

Ground rupture

24
Q

What are the secondary impacts of seismic events?

A
Soil liquefaction
Landslides
Tsunamis
Fires
Effects on people and built environment