Transcript Seismic Activity on the West Coast

Seismic Activity on
the West Coast
“Waiting for the Big One”
Earthquakes in Western Canada
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Most earthquake prone region in Canada
Part of the Pacific Ring of Fire, the
concentration of earthquakes along the
west coast is related to the presence of
active faults, or breaks in the earth's crust
Plates can either slide past one another, or
they can collide, or they can diverge
Pacific Ring of Fire
Earthquakes in Western Canada
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The west coast of Canada is one of the few
areas in the world where all three types of
plate movements take place
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Subduction – Sliding past one another
Collision – Crashing into one another
Divergence – Moving away from one another
Plate Movements on the West Coast
Cascadia Subduction Zone
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Here, the much smaller Juan de Fuca plate is sliding
(subducting) beneath the North American plate
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Juan de Fuca and North America plates are currently locked
together, causing strain to build up in the earth's crust.
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At some time in the future, these plates will snap loose,
generating a huge offshore "subduction" earthquake - one
similar to the 1964 M=9.2 Alaska earthquake, or the 1960
M=9.5 Chile earthquake
Japanese Tsunami
Tsunamis
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A tsunami is a wave train, or series of waves,
generated in a body of water by an impulsive
disturbance that vertically displaces the water
column
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Subduction earthquakes are particularly effective
in generating tsunamis
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As the tsunami's speed diminishes as it travels
into shallower water, its height grows
http://www.youtube.com/watch?v=4YPOK_3r8Dc
http://www.theguardian.com/world/video/2011/mar/12/japan-confronts-quake-devastationvideo
Tsunamis
What do we need to do as a class?
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Take cover under a table or desk, hold on
Stay away from doors and windows
Count to 60 seconds in unison
Wait 10 seconds
Count to 60 in unison again
Stay calm, evacuate carefully to exit
Homework
1.
Draw, label and colour the tectonic processes on the
Pacific Coast
2.
Include in your diagram of tectonic processes:
- North America Plate
- Juan de Fuca Strait
- Juan de Fuca Ridge
- Pacific Plate
- Direction of plates
- Seattle
- Vancouver
- Victoria
- Vancouver Island
- Cascade Volcanoes
- Megathrust Quakes