EESA06H3 Lecture Notes - Toffee, Asthenosphere, Lithosphere
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- 400-500 million years for one Wilson cycle to happen.
-Pangaea 2 will occur in 250 million years
Part 1: what do earthquakes tell us about the plant’s interior and plate tectonics
Part 2: plates and their margins
Part 3: earthquakes in Canada
-Seismic energy is used to map the earths interior
-drilling 12 km is a physical limit to drilling because its starting to get pretty hot down there
Earthquakes: what can we learn of the earth’s interior?
-rocks are brittle, they snap, once it snaps the energy produce is the earthquake
-the focus is the focus point under the surface of the earth, the epicentre is where the earthquake
-the line of breakage is called the fault plane, seismic waves are then produced
-there are many blind faults in the US, that can potentially produce earthquakes, but we can see.
Surface waves: they go around the surface of the planate, its usually these waves that do the damage
-There are two types of waves:
-Primary waves, that go 5-7 km/s
-Secondary waves, which is the last type of energy wave to arrive, that go 2-4 km/s
P-Wave Shadow Zones
-pwaves can go through fluid
-cant go through fluid
-trying to image the earth’s interior
-can measure temperature and pressure
-the relationship between the plate boundaries and the hot rocks. The spreading center are underlying
of very hot rocks. The hot red areas are plumes. The blue spots are cooler.
Lithosphere: hard outer crust of the earth
We are halfway through the longevity of the planet, until it becomes a dead planet.
Asthenosphere: means weak rock, in which that rock is moving (hot toffee)
The mohorovicic discontinuity is the base of the crush
Crust plus asthenosphere equals lithospheric plate
A lithosphereic plate is crust plus asthenosphere
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