Earthquakes

Question 1

What is an earthquake?

Answer 1

Vibrations of the Earth’s crust caused by movement at plate boundaries and major fault lines

Question 2

What is the epicentre?

Answer 2

The point on the earth’s surface directly above the focus of an earthquake

Question 3

What is a fault line?

Answer 3

A line on the earth’s surface that traces a geological fault

Question 4

What is a focus?

Answer 4

The point in the earth’s crust where the earthquake happens

Question 5

What is stress and release?

Answer 5

When pressure builds between two plates, stress is placed on the fault line and when it builds up it is released

Question 6

What is the Mercalli Scale measure?

Answer 6

The intensity of the earthquake

Question 7

What is used to measure a magnitude?

Answer 7

A seismometer

Question 8

What scale does the Mercalli Scale use and how does it work?

Answer 8

Logarithmic scale, e.g. size 6 is 10x larger than 5 and 100x larger than 4

Question 9

What are primary waves?

Answer 9

They arrive first and fast, moving through solid rock and fluids, pushes and pulls in the direction of travel

Question 10

How do primary waves travel?

Answer 10

At about 8km/s and transfer energy from the focus to the epicentre

Question 11

What are secondary waves?

Answer 11

They move slower than primary waves; only move through solid rock in an up and down motion

Question 12

How do secondary waves travel?

Answer 12

At about 4km/s and transfer energy from the focus to epicentre

Question 13

What are love waves and how do they move?

Answer 13

They arrive 20-30 secs after the P&S waves, only travel through the surface crust in a rolling motion which results in the ground moving side to side, shaking it

Question 14

How do Rayleigh waves move?

Answer 14

They only travel through the surface of the crust, fastest waves move up and down

Question 15

Why did the 2010 earthquake occur in Haiti?

Answer 15

• It is on a conservative fault
• Small depth (8-10km)
• Port-au-Prince only 15km away from the epicentre

Question 16

What is the population density of Ouest (Haiti’s capital state)?

Answer 16

808.7/km^2 (high density)

Question 17

How did Haiti’s building standards affect the Haiti earthquake?

Answer 17

• Poor quality concrete, weak cement
• No building code
• Seismic design is not taken aboard

Question 18

How many injuries and fatalities occured in Haiti?

Answer 18

316,000 and 300,000

Question 19

What is Haiti’s life expectancy and GDP per person a year?

Answer 19

60, $650

Question 20

What other earthquakes have hit Haiti?

Answer 20

• 1887, severe damage/tsunami

- 1994, damaged houses in a remote location

Question 21

What were some primary effects of the Haiti earthquake?

Answer 21

• 8 hospitals were badly damaged
• 100,000 houses destroyed
• 80% of schools in the capital were destroyed

Question 22

What are some secondary effects of the Haiti earthquake?

Answer 22

• 80% of population on less than a dollar every day
• Dead bodies under buildings caused outbreaks of cholera
• Many people moved into tents and got diseases from dirty water
• 1.3 million Haitians became homeless
• Frequent power cuts which made it hard for hospitals to cope