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Inside the Earth #3
Term | Definition |
---|---|
tension | stress that stretches rock so that it becomes thinner in the middle |
compression | stress that squeezes rock until it folds or breaks |
shearing | stress that pushes masses of rock in opposite directions in a sideways movement |
normal fault | one where the hanging wall slides downward; caused by tension in the crust |
reverse fault | one where the hanging wall slides upward; caused by compression in the crust |
strike-slip fault | one where rocks on either side move past each other sideways with little up or down motion |
focus | the point beneath Earth's surface where rock breaks under stress and causes an earthquake |
epicenter | the point on Earth's surface directly above an earthquake's focus |
magnitude | the measure of an earthquake's strength based on seismic waves and movement along the fault |
Richter scale | a scale that rates an earthquake's magnitude based on the size of its seismic waves |
liquefaction | the process by which an earthquake's motion suddenly turns loose soil into liquid mud |
aftershock | an earthquake that occurs after a large earthquake in the same area |
tsunami | a giant wave usually caused by an earthquake beneath the ocean floor |