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Earthquakes
Science
Term | Definition |
---|---|
Stress | A force that acts on rock to change its shape or volume |
Tension | |
Compression | squeezes rock until it folds or breaks |
Shearing | Stress that pushes a mass of rock in two opposite directions |
Normal Faults | Tension in Earth's crust pulls rock apart |
Hanging wall | The block of rock that lies above |
Footfall | The block of rock that lies below |
Reverse fault | has the same structure as a normal fault, but the blocks move in opposite direction |
Strike-Slip fault | Rocks on either side of the fault slip past each other sideways,with little up or down motion |
Anticline | A fold in rock that bends upward into an arch |
Syncline | A fold in rock that bends downward to form a valley |
Plateau | A large area of flat land elevated high above sea level |
Earthquake | is the shaking and trembling that results from the movement of rock beneath Earth's surface |
Focus | is the area beneath Earth's surface where rock that is under stress breaks, triggering an earthquake |
Epicenter | The point on Earth's surface directly above the focus |
P waves | First waves to arrive |
S waves | After p waves comes secondary waves |
Surface waves | Move more slowly than P waves and S waves, but they can produce severe ground movements |
Mercalli Scale | was developed to rate earthquakes according to the level of damage at a given place |
Magnitude | Number that geologists assign to an earthquake based on the earthquake's size |
Richter scale | Rating of an earthquake's magnitude based on the size of the earthquake's seismic waves |
Seismograph | The seismic waves are measured by a seismograph |
Moment Magnitude Scale | A rating system that estimates the total energy released by an earthquake |