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science page 101
Term | Definition |
---|---|
stress | a force that acts on rock to change its shape or volume |
tension | the stress force that pulls on the crust and thins rock in the middle |
compression | the stress force that squeeze rock until it folds or breaks |
shearing | stress that pushes a mass of rock in two opposite directions |
normal fault | the fault cuts through rock at an angle, so one block |
reverse fault | same structure as a normal fault, but the blocks move in opposite directions |
strike-slip fault | the rocks on either side of the fault slip past each other sideways, with little up or down motion |
plateau | a large area of flat land elevated high above sea level |
earthquake | the shaking and trembling that results from movement of rock beneath Earth's surface |
focus | the area beneath Earth's surface where rock that was under stress begins to break or move |
epicenter | the point on the surface directly above the focus |
P wave | seismic waves that compress and expand the ground like an accordion |
S wave | seismic waves that can vibrate form side to side or up and down |
suface wave | slower than P and S waves, but they can produce severe ground movements |
seismograph | an instrument that records and measures an earthquake's seismic waves |
Modified Mercalli scale | rates the amount of shaking from an earthquake |
magnitude | a single number that geologists assign to an earthquake based on the earthquake's size |
Richter scale | the earliest magnitude scale |
moment magniude scale | rate the total energy an earthquake releases |
seismogram | the pattern of lines that is record an earthquake's seismic waves produced by a seismograph |