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Flashcards in Seismicity Deck (24)
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1

What is seismicity? (seismicity tectonics)

The phenomenon of earthquake activity

2

What is an earthquake? (seismicity tectonics)

The sudden release of energy that creates seismic waves that read out spherically

3

Where do earthquakes tend to occur? (seismicity tectonics)

Conservative (but can occur on any place margin)

4

What is the epicentre? (seismicity tectonics)

The point on the Earth's surface directly about the focus

5

What is the focus point? (seismicity tectonics)

The point in the ground where pressure is released

6

What are the three types of focus point? (seismicity tectonics)

- Shallow focus
- Intermediate focus
- Deep focus

7

What is the depth and damage of a shallow focus? (seismicity tectonics)

0-70km
greatest damage, releasing 75% of energy

8

What is the depth and damage of an intermediate focus? (seismicity tectonics)

70-300km
Moderate damage

9

What is the depth and damage of a deep focus? (seismicity tectonics)

300-700km
Minimal damage

10

What are some of the factors that the impact of an earthquake is dependent on? (seismicity tectonics)

Focus
Strength
Time
Rock type
Development
Land use

11

If a primary effect is the ground shaking leading to collapse of infrastructure, what is the secondary and long term effects of this? (seismicity tectonics)

- Fires
- Deaths
- Disease
- High unemployment
- Homelessness

12

If a primary effect is schools being destroyed, what is the secondary and long term effects of this? (seismicity tectonics)

suspended education leading to a lost generation

13

If a primary effect is homelessness and starvation, what is the secondary and long term effects of this? (seismicity tectonics)

NGO's provide tents, food and water which may become a long term issue

14

What are P-waves? (seismicity tectonics)

- Primary waves
- Compressional
- Fastest wave
- Travels through any solid
- In the air, takes the form of a sound wave

15

What are S-waves? (seismicity tectonics)

- Secondary waves
- Transverse (ground is displaced perpendicularly to the movement)
- Will only travel through solids
- Medium speed and relatively destructive

16

What are Surface waves? (seismicity tectonics)

- Travels near to the surface
- Slowest and most destructive wave
- Long waves cause the ground to move sideways

17

How does the Mercalli scale work? (seismicity tectonics)

Measures the amount of damage caused by an earthquake and uses descriptions of damage and photos to describe the intensity

18

According to the Mercalli scale, what is the description and observation of a level 1 earthquake? (seismicity tectonics)

instrumental - only detected by seismographs

19

According to the Mercalli scale, what is the description and observation of a level 6 earthquake? (seismicity tectonics)

Strong - trees sway and some damage is caused

20

According to the Mercalli scale, what is the description and observation of a level 12 earthquake? (seismicity tectonics)

Catastrophic - total destruction

21

How does the Richter scale work? (seismicity tectonics)

Measures the amount of seismic energy released by the earthquake, using a seismography to record the amount of energy realised on a scale of 1-9

22

According to the Richter scale, what is the description of a 0-2 earthquake? (seismicity tectonics)

Not felt by anyone

23

According to the Richter scale, what is the description of a 5-6 earthquake? (seismicity tectonics)

furniture will move

24

According to the Richter scale, what is the description of a 8-9 earthquake? (seismicity tectonics)

total destruction