Transcript Earthquakes - Mr Phillips` IB Geog

1. Characteristics of Hazards
Describe and explain the
characteristics and spatial distribution
of your chosen hazards.
EARTHQUAKES
Visit the USGS website.
• Open up the ‘Real-time Earthquake Map’.
• Have a play with the different variable
controls.
• Make a note of WHERE earthquakes are
occurring around the world.
• Can you describe any distinct patterns?
• Begin to plot areas of earthquake activity
onto your world map.
Describe the global spatial
distribution of earthquakes:
•
•
•
Recap: There are 4 plate margins…
CONSTRUCTIVE
DESTRUCTIVE
CONSERVATIVE
COLLISION
Add these annotations to your plate margin diagrams.
Homework
• Print out the PDF document I have
emailed you.
• Draw on each of the tectonic plates. This
is harder than it looks, but Year 8
managed!
• Label each of the plates, and indicate what
type of plate margin each is.
• Add some colour and stick together.
So, WHY do the plates move?
The continual heating and cooling
creates pockets of movement
called convection cells
“Convection cell”
The heated rock
expands,
becomes less
dense, and rises
to the surface
HEAT SOURCE- Radioactive
decay in the core
Explain why Earthquakes occur,
using the following terms:
• Plate boundary, friction, pressure, energy,
seismic shock wave, focus, epicentre.
Shock Waves
• These are energy waves created by the
pressure release when two plates slip past
eachother.
• These travel below the surface of the
Earth.
These are fast moving and can travel through solids and liquids.
These are slower and can travel through solids only.
Surface Waves
• Energy released by Earthquakes can be
transferred as movement along the Earth’s
surface.
• The two wave types are Love waves and
Rayleigh waves.
These are fast moving and do not tend to affect bodies of water.
These can be very destructive on solid ground.
These are slower moving, and their motion can disrupt bodies of
water, creating large waves and currents.
Measuring Earthquakes
• Richter Scale:
This measures the
energy released by
an earthquake.
It is a logarithmic scale,
which means that a
Scale 6 ‘quake is 10
times more powerful
than a Scale 5 ‘quake.
Measuring Earthquakes
• Mercalli Scale
This measures the
damage
experienced as a
result of an
earthquake, and is
calculated by
visual evidence.
http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf
Analyse these two techniques
Richter
Str
en
gth
s
We
akn
ess
es
Mercalli
Where would these rank on the Mercalli scale?