Earthquakes Flashcards
what is an earthquake?
Sudden movement of the earth’s crust caused by the release of stress accumulated along geologic faults, volcanic activity or other sudden stress changes (natural or artificial) in the Earth (CAUSE).
the resulting ground shaking and radiated seismic energy (EFFECT)
what causes earthquakes?
meteorite impact, volcanic eruptions, nuclear explosions and faults,
what causes the largest earthquakes?
meteorite impact
what range are strike values between?
0 - 360 degrees
what is the strike?
The strike is the compass direction of a rock layer along the line of its intersection with a horizontal surface
what is the dip angle?
The dip is the angle and direction of the steepest descent of a rock layer from the horizontal, measured at right angles to the strike.
what range are dip angles between?
0 - 90 degrees
what is the rake?
The angle between the strike and the slip direction measured in the counter clockwise direction on the fault plane
what values are rake angles between?
180 - 180
what does a rake of -45 indicate?
left normal
what does a rake of 150 indicate?
right reverse
what does a rake of -150 indicate?
right normal
what does a rake of 45 indicate?
left reverse
describe a dip slip fault
the slip direction is parallel to the dip direction
describe a strike slip fault
the slip direction is parallel to the strike
direction
