plate boundaries/earthquakes Flashcards
1
Q
fracture
A
break in rocks or sediment
2
Q
faults
A
fractures that have motion along them in some direction
3
Q
fault plane
A
plane of that fracture; not usually a flat surface
4
Q
divergent margins
A
horizontal crustal extension
5
Q
faulting
A
caused by horizontal motion and crustal shortening
6
Q
convergent plate boundary
A
shallow earthquakes
7
Q
types of faults
A
- strike slip
- normal
- reverse
- thrust
- blind thrust
- strike and dip
8
Q
thrust fault
A
lower angle reverse (<45)
9
Q
blind thrust fault
A
- softer rocks
- dangerous
10
Q
strike and dip
A
- looking at horizontal angle
- strike direction and the dip angle
- horizontal line on the dipping surface (strike)
11
Q
stress
A
forces apllied on a rock
12
Q
strain
A
change in shape of the rock in response to stress
13
Q
what is the elastic rebound theory
A
- typical rocks deform elasticity
- opposite sides of fault are deformed instead of moving
- movements along the fault when rocks undergo brittle failure
- when shear stress> shear strength, rock mass fails suddenly by faulting
14
Q
generating earthquake energy
A
- rocks slide past one another along a fault
- fault motion cannot occur forever
- fault motion is arrested by friction
15
Q
releasing bends
A
- step produces a component of extension
- causes a rupture
- right lateral fault with a right bend is releasing
