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26 Cards in this Set

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focus
the point beneath the Earth'surface where rock that is under stress breaks, triggering an earthquake
Surface waves
they move more slowly that S waves and P waves, but they produce the move severe ground movements
epicenter
the point on the surface directly above the focus
seismograph
records the ground movements caused by seismic waves as the move through the Earth
earthquake
shaking and trembling that results from the movement of rock beneath Earth's surface
stress
a force that acts on rock to change its shape or volume
magnitude
a measurment of an earthquake strength based on seismic waves and movement along faults
shearing
stress that pushes a mass of rock in two opposite directions

it can cause rock to break and slip apart or to change its shape
Mercalli scale
developed to rate earthquakes according to their intensity
tension (extension)
stress that pulls on the crust, strechiong rock so that it becomes thinner in the middle
compression
stress that squeezes rock until it folds or breaks
deformation
any change in the volume or shape of Earth's crust
fault
a break in Earth's crust where slabs of crust slip past each other
faults usually occur along plate boundaries,where the forces of plate motion compress,pull,or shear the crust so much that the crust breaks
Richter scale
a rating of the size of seicsmic waves as measured by a particular type of mechanical seismograph
strike-slip fault (shearing)
the rocks on either side of the fault slip past each pther sideways with little or no up-or-down motion
seismic waves
vibrations that travel through Earth carrying the energy released during an earthquake
they carry the energy of an earthquake away from the focus,through the Earth's interior,and across the suface
normal fault (tension)
the fault is at an angle, so one block or rock lies above the fault (hanging wall) and one lies below (foot wall)
What are the 3 types of seismic waves?
P waves
S waves
Surface waves
reverse fault (compression)
same as normal fault but the blocks move in the opposite direction
P waves (primary waves)
earthquake waves that comress and expand the ground like an accordian
moment magnitude scale
a rating system that estimates the total energy released by an earthquake

this scale can rate earthquakes of whatever size, near or far
fault-block mountain
a mountain that forms where a normal fault uplifts a block of rock
syncline
a fold in rock that bends downward in the middle to form a bowl
anticline
a fold in rock that bends upward into an arch
S waves (secondary waves)
earthquake waves that vibrate from side to side as well as up and down
plateau
a large area of flat land elevated high above sea level