Earthquakes 2 / Tsunamis

Question 1

Explain Earthquake Hazards?

Answer 1

Any physical phenomenon that may produce adverse effects on human activities

Question 2

Explain Primary vs Secondary Hazards

Answer 2

Primary: caused by fault movement (ground shaking)
Secondary: casued as a consequence of ground shaking (ground shakes, than things happen)

Question 3

Explain the primary hazards at Christchurch?

Answer 3

• collapse of 2 buildings
  185 deaths, 7000 injured
  combined faults: surface rupture over a distance of 120 km

Question 4

Explain secondary Hazards at Christchurch

Answer 4

• Land Elevation change

Question 5

Explain Liquefaction (Secondary hazard)

Question 6

what are the 3 ingrediants for liquefaction?

Answer 6

• Loose Sandy or silty soil
• Saturated Soil
• Ground shaking

Question 7

What are the impacts of liquefaction on water quality and habitats

Answer 7

• Cloudy or contaminated water
• Decreased levels of O2
• Habitats smothered by silt (reduce biodiversity)
• Decrease in air quality

Question 8

What is liquefaction

Answer 8

do to shaking of earthquake, soil loses its strength, and behaves like a solid

Question 9

What is a Subduction Zone Earthquake

Answer 9

aka Megathrust earthquakes
- convergent plate boundaries
- subduction zones are only plate boundary that produces earthquakes over M8.5

Question 10

What is a thrust fault?

Answer 10

Less than 45 degrees

Question 11

What is “Asperity”?

Answer 11

Area on an active fault that is stuck or locked
- Subduction zone - wide

Question 12

What are the 3 plates on the Cascadia Subduction zone?

Answer 12

Juan De Fuca, Explorer, Gorda

Question 13

What is a Tsunami?

Answer 13

Wave or series of waves caused by a displacement of a large volume of water

Question 14

how are tsunamis generated?

Answer 14

by seismic activity, landslides, volcanic eruptions

Question 15

Explain wavelengths

Answer 15

• very long
• wave heights over 1m (in deep ocean)
• increase in height closer to land

Question 16

Tsunami Causes

Answer 16

• Seismic activity
• Landslides
• Volcanic Eruptions
• Meteor impact

Question 17

What earthquake magnitude on richter scale does it need to be for damaging tsunami to occur

Answer 17

M7.5 or greater

Question 18

What 3 things happens when waves approach land?

Answer 18

• water depth decreases
• wave speed decreases
• wave height increases

Question 19

Name some tsunami impacts

Answer 19

• destruction of land and infrastructure
• debris carried by water
• injury and death
• contaminated drinking water
• Disease (malaria and cholera)
• Impacts don’t dissapear overnight, can be many years till recovery

Question 20

Explain the Sumatra - Andaman Earthquake (occurred in Indian Ocean)

Answer 20

• M9.1; MM =IX in areas
• Rupture along fault between Burma Plate and Indian Plate
• No warning system in Indian Ocean

Question 21

What is the Tsunami warning system name?

Answer 21

DART: Deep-Ocean Assessment and Reporting Tsunamis