Unit 1 SAC 2 - Earthquakes

Question 1

Explain Convection Currents and how they cause Plate Tectonics

Answer 1

Convection currents are driven by heat. As the heat from the earths core warms the molten rock in the mantle, it rises. As the liquid rises it cools causing it to sink back towards the core where it heats once again. This cycle creates a current.

The crust floating on the mantle moves in the direction of the convection current creates tectonic activity by causing the plates to converge/diverge/transform.

Question 2

Oceanic versus Continental Plates

Answer 2

Oceanic plates are denser, heavier and thicker than Continental plates. Oceanic plates are approx. 6km thick vs Continental plates 10-30km.
Oceanic plates are made of basalt or sima (silica/magnesium mix).
Continental plates are mainly granite.

Question 3

Define Plate Tectonics

Answer 3

Theory of how landforms are created from geological processes.

Question 4

List 5 statistics for the 2010 Haiti Earthquake

Answer 4

7 magnitude
300 000 buildings destroyed
220 000 dead
250 000 injured
1.3 million homeless
60 aftershocks
After earthquake population under poverty line increased from 50% to 80%.
8 190 died from Cholera (Cholera was brought into the country from a UN peace-trooper assisting with the earthquake recovery).
Before earthquake: 2/3 were under or unemployed.
Other stats could include: hospital beds, number of camps, $ aide money,
$ cost of recovery etc….

Question 5

Name the two plates involved in the 2010 and 2021 Haiti Earthquakes

Answer 5

Caribbean Plate and Gonave Microplate

Question 6

Compare the locations of the 2010 and 2021 Haiti Earthquake.

Two similarities
Two differences

Answer 6

Similarity: Both earthquakes occurred along the Goave and Caribbean Plate boudnary.
Similarity: Both earthquakes occurred west of the capital Port-au-Prince

Difference: The 2010 earthquake was only 24km from Port-au-Prince. The 2021 earthquake was 125km from Port-au-Prince. 100km difference.
Difference: The focus of the 2010 Earthquake was 13km, whereas the 2021 focus was 10km deep. 3km Difference. NOTE: this is also a similarity as they are both shallow. Depends how you phrase it.
Difference: the 2010 earthquake occurred in a more urban setting compared to the 2021 earthquake that mainly impacted small rural villages.

Question 7

Explain what a Collision Margin is?

Give an example.

Answer 7

A Collision margin is a type of convergent plate boundary. It is where two continental plates are converging. As they collide, fold mountain ranges are formed.

Example: Eurasian and Indian Plate Boundary which formed the Himalayan Mountains.

Question 8

Explain what a Divergent Plate Boundary is.

Give an Example?

Answer 8

A Divergent Plate boundary is where two plates are moving apart. New land forms between the plates. Rifts and Ridges form along divergent plate boundaries.
Example: Pacific Plate and the Antarctic Plate.
Also the Mid-Atlantic Ridge formed by diverging Eurasian and North American Plates.

Question 9

What type of plate boundary occurs when an Oceanic and Continental Plates converge?

Answer 9

A destructive plate margin (also known as subduction). It is a type of convergent plate boundary.
The Oceanic plate boundary is forced beneath the lighter continental plate. As the oceanic plate is forced beneath, it heats, melting the rock and releasing gasses. This magma and gasses are forced to the surface as a volcanic eruption.

Question 10

What two landforms are created when two Oceanic Plates converge.

Answer 10

1. Trench

2. Island Arc

Question 11

List 5 stats for the 2021 Haiti Earthquake.

Answer 11

7.2 magnitude
50 000 Buildings destroyed
2248 Deaths
12200 Injured
30 000 homeless
900 aftershocks

Question 12

Compare the depth of the 2010 and 2021 Haiti Earthquakes.

Why do we consider the depth of an earthquake?

Answer 12

Similarity: Both 2010 and 2021 earthquakes were shallow.
Difference: The 2021 earthquake was 3km shallower than the 2010 earthquake. 10km and 13km respectively.

The deeper the earthquake the greater the amount of energy that is absorbed by the lithosphere (crust) before it reaches the surface.

Question 13

In general, how does the depth of an earthquake change as you move away from the plate boundary.

Answer 13

The depth of earthquake increases (in general) as the distance from the plate boundary increases.

Question 14

Name the capital of Haiti

Answer 14

Port-au-Prince

Question 15

What is the Richter Scale?

Answer 15

The Richter scale is a measurement of the energy output of an earthquake. Each increase of 1 unit on the Richter Scale is 10 times the energy output of the previous scale.

Question 16

Identify some of the contributing factors that lead to the 2010 Haiti earthquake becoming a disaster.

Answer 16

• Lack of building regulations
• Lack of quality building materials
• Lack of a land registry
  *

Question 17

Identify some of the contributing factors that lead to the 2021 Haiti earthquake becoming a disaster.

Answer 17

• Assassination of the president Jovenal Moise on 7/7/22 leading to political instability. During the earthquake they had an incumbent President.
• Hurricane Grace hit Haiti two days after the earthquake on 16/8/22. This halted much of the earthquake recovery.
• 90 Gangs currently operating in Haiti. Considered more powerful than the police. They looted aide trucks taking food, drinking water and medicine. They also kidnapped doctors for ransom. On 23/8 two rival gangs agreed to a ceasefire to enable the aide trucks to use the roads between Port-au-Prince and the affected villages. Some trucks were still looted.
• As with 2010 earthquake - poorly constructed buildings could not withstand the earthquake. Made of cheap, heavy concrete they collapsed on those inside.

Question 18

What else should you be revising?

Answer 18

Two responses to the 2010 earthquakes.

Evaluation of one of the responses.