Earthquakes [U1] Flashcards
Define the terms “Focus” and “Epicentre”
Focus - Where energy is released underground due to pressure build up
Epicentre - Where energy hits the surface of Earth, above the Focus
Why are shallow focus earthquakes more destructive?
They happen close to the surface of Earth, meaning more energy is conserved as there is less distance between the focus and epicentre.
Aftershocks happen after the main shock. Why can aftershocks be more devastating?
Weakened buildings get damaged more and may collapse easier. Some people may reenter buildings which can collapse and cause death.
Define the terms “Body waves” and “Surface Waves”.
Body waves - transmitted through below the surface of Earth
Surface Waves - Spread out along the surface
Name the 4 different types of waves and their classification
Body waves:
- Primary waves
- Secondary waves
Surface waves:
- Love waves
- Rayleigh waves
What is the difference between primary and secondary waves?
Primary - faster than S waves, moves through both solids and liquids, shakes the Earth back and forth in compression
Secondary - slower than P waves, can only move through solid, shakes the Earth side to side that buildings can’t cope with
What is the characteristics of Love waves and Rayleigh waves?
Love - ground moves sideways, moves through solids only, faster than Rayleigh waves
Rayleigh - ground moves up and down in a circular motion, moves through solids only, slower than Love waves, spread out more
Define the term “Liquefaction”.
Earthquakes weaken soil integrity. If the soil is saturated, it can turn into mud which causes buildings and other heavy properties to sink in the ground.
Name a Secondary Hazard for an Earthquake.
Rockfall, Landslide, Tsunamis, Flooding
Name a Secondary Impact for an Earthquake.
Homelessness, Economic Losses, Loss of Life
