Earthquakes and Seismic Waves (2.2)
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Created by:
talirocks97 on October 12, 2010
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15 terms
Terms | Definitions |
|---|---|
 what is an earthquake? | the shaking and trembling that results from the movement of rock beneath earth's surface |
| what is the focus? | the area beneath earth's surface where rock that is under stress breaks, triggering an earthquake |
| what is the epicenter? | the point on the surface directly above the focus |
| what is the motion of seismic waves? | they carry energy from an earthquake away from the focus, through earth's interior, and across the surface |
| what are the 3 main categories of seismic waves? | P waves, S waves, surface waves |
| what are P waves? | primary waves are the first ones to arrive; they compress and expand the ground like an accordion; they travel through solids and liquids |
| what are S waves? | secondary waves come after P waves; these waves shake the ground from side to side and up and down; S waves only move through solids |
| what are surface waves? | when P and S waves reach the surface they become surface waves; surface waves are the slowest waves but they are very dangerous; they make the ground roll like ocean waves |
| what are 3 commonly used methods of measuring earthquakes? | mercalli scale, richter scale, moment magnitude scale |
| what is the mercalli scale? | rate earthquakes according to the level of damage at a given place |
| what is the richter scale? | rating of an earthquake's magnitude based on the size of the earthquake's seismic waves; works best for small and nearby earthquakes |
| what is magnitude? | a number based on the earthquake's size |
| what is a seismograph? | an instrument that records and measures seismic waves |
| what is a moment magnitude scale? | a rating system that estimates the total energy released by an earthquake |
| how do geologists locate the epicenter? | by using seismic waves; they measure the difference between the arrival times of the P and S waves. the farther away an earthquake is, the greater the time between the arrival of the waves |
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