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20. Crustal Deformation II (p. 279-288; 290-291)
Brittle Structures
Faults
Whereas joints form by fracturing a rock in such a way that the two sides of the joint just move apart from
each other, with faults the two sides of the fracture start to slide past each other. This may result in a lot of
energy can be released, as an ______________.
What is the most common type of location where faults occur?
________________________________ ______
The only reason that tectonic plates are able to move past each other is because of the faults between
the plates.
Examples of faults at tectonic plate boundaries:
1. The _______________________ fault separates the North American and Pacific plates in
California.
2. The _______________________ region has faults along the boundary of the North American
and Juan de Fuca plates. An examp le of a recent earthquake in this region was the M6.8
__________________ earthquake on 2/28/01.
3. The _______________________ region, where many countries are prone to earthquakes
(e.g., Japan, Taiwan, Phillipines).
Faults can occur a long way from the plate boundaries , producing a second class of earthquakes in
regions referred to as _________________________. Some of these may be ancient faults that are no
longer active, but many are still active today.
Where was the largest earthquake in the recorded history of the continen tal United States in the winter of
1811-1812? _____________________________________
There were 3 large earthquakes all above a magnitude 7, the largest an 8.1. The faults that produced
these earthquakes are nowhere near a plate boundary.
What causes the two sides of a fault to slide past each other? _____ _______________
This stress comes from the motion of the tectonic plates and either pu lls or pushes on the faults, causing
them to slip.
Any fault that is inclined with respect to horizontal has the rocks on one side of the fault sitting on top of
rocks on the other side of the fault.
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