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Science Extra Credit~Summer Schuster
Unit 8: Plates, Quakes and Canos'
Terms in this set (16)
Who was Alfred Wegener?
a scientist who studied the continents, he is known for Continental Drift, BUT he could not explain why it was happening.
Who was Harry Hess?
A geologist and Navy submarine commander during WWII, and who brought to light seafloor spreading (he used sonar to develop a 3D map of the seafloor, and discovered the mid-oceanic ridge).
What is older, surface rocks or seafloor rocks?
SURFACE ROCKS! (they are billion of years old, while seafloor rocks are less than 200 million years old)
they are a sudden movement that commonly occur at boundaries (tend to be zones of seismic activity). (earthquakes that occur along divergent and transform plate boundaries tend to be shallow or WEAK. the deeper the earthquake, the STRONGER it is)
What is a deformation?
change of shape
what is compression stress?
when two things are pushed together (think of pbj sandwich)
what is tension stress?
stress that pulls a material apart
what is shear stress?
Different parts of a mass are moved in opposite directions along a plane
what is torsion stress?
Mass is subjected to twisting
what is a focus?
point below where the earthquake starts.
what is a fault?
A break in the earth's crust
what is the epicenter?
the point on the surface directly above the focus (seismic waves are usually the strongest here).
what is the difference between elastic and plastic deformation?
elastic~ when stress is applied, it deforms, but returns to original shape when stress is removed.
plastic~ when stress is applied, it deforms, but doesn't return to original shape.
how do you find the epicenter of an earthquake?
where all 3 of the circles ,made from your compass, overlap: it's the epicenter of an earthquake.
what are primary waves?
p-waves are the fastest seismic wave (travel at 5 km/s-7 km/s), travel through solids and liquids, have a forward and backward motion.
what are secondary waves?
s-waves are slower than p-waves because they can only travel through solids, and have a side to side motion.
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