Earthquakes and tsunamis

Question 1

What is a focus of an earthquake?

Answer 1

The breaking point of the earthquake

Question 2

What is an epicentre?

Answer 2

The point on the surface above the focusWa

Question 3

What are the 4 different types of seismic shockwaves?

Answer 3

P (primary/pressure) waves
S (secondary/shear) waves
L (surface love) waves
R (rayleigh) waves

Question 4

Describe P waves.

Answer 4

• the fastest waves and reach the surface first
• high frequency
• push through crust, mantle and core

Question 5

Describe s waves.

Answer 5

• reach the surface after p waves
• high frequency
• shake through crust and mantle

Question 6

Describe L waves

Answer 6

• the slowest waves
• moves side to side
• cause the most damage

Question 7

Describe R waves

Answer 7

• radiate up and down from the epicentre

Question 8

What generally creates tsunamis?

Answer 8

earthquakes

Question 9

How small is the wave height of tsunamis?

Answer 9

less than 1m but can rise to over 25m once it reaches the shore

Question 10

What is the wavelength of tsunamis?

Answer 10

very long- anything between 100 and 1000km

Question 11

What is the speed of tsunamis?

Answer 11

quickly- anything between 640 and 960km per hour

Question 12

Is there only one tsunami at a time?

Answer 12

usually consists of a series with the first not always being the biggest

Question 13

What are the warning signs that an earthquake is imminent?

Answer 13

• microquakes
• bulging of the ground
• raised ground water levels
• electrical and magnetic changes within local rocks
• curious animal behavior
• increased argon gas
• decrease in radon gas

Question 14

How can the risk of tsunamis and earthquakes be reduced?

Answer 14

• Geographic information systems
• Earthquake preparation skills
• Earthquake drills
• Reinforce infrastructure

Question 15

What is the Modified Mercalli intensity scale?

Answer 15

• measures the actual intensity of damage caused
• numbers between 1 and 12:
  1- tiny
  5-moderate
  7- destructive
  12- catastrophic

Question 16

Describe the global distribution of earthquakes.

Answer 16

• mostly occur along the NW side of the ring of fire
• nearly all take place along a plate margin

Question 17

Describe an earthquake at a constructive plate margin

Answer 17

close to the surface and narrowly concentrated

Question 18

Describe an earthquake at a conservative plate margin

Answer 18

narrow zone of usually shallow-depth earthquakes

Question 19

Describe an earthquake at a destructive plate margin

Answer 19

has shallow and deep earthquakes

Question 20

Why do tsunamis get bigger when they reach the shore?

Answer 20

The sea bed starts to interfere with the wave motion and slows it down, making the wave length shorter

Question 21

Where is the ring of fire located?

Answer 21

Pacific plate/ ocean

Question 22

How do you make a building earthquake proof?

Answer 22

• rolling weights on roof
• rubber shock absorbers at base
• interlocking steel frame

Question 23

What is liquefaction?

Answer 23

when saturated soil loses its strength and stiffness as a result of shaking and causes it to behave like liquid