JLKR+2.2

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Vocabulary
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 * Focus**: is the point beneath earth's surface where rocks that are under stress break, triggering an earthquake
 * Epicenter**: the point on the surface directly above the focus
 * Seismic waves**: the vibrations that travel through Earth carrying the energy released during an earthquake
 * P waves**: earthquakes waves that compress and expand the ground like an accordion
 * S waves**: earthquakes waves that vibrate from side to side as well as up and down
 * Surface waves**: when P waves and S waves reach the surface, some of them become surface waves
 * Seismograph**: records the ground movements caused by seismic waves as they move through earth
 * Magnitude**: is a measurement of earthquake strength based on seismic waves and the movement along the faults
 * Mercalli scale**: was developed to rate earthquakes according to their intensity
 * Richter scale**: is a rating of size of seismic waves as measured by a particular type of mechanical seismograph
 * Moment magnitude scale**: a rating system that estimates the total energy released by an earthquake

Seismic Waves

 * Primary waves
 * P Waves
 * compress and expand the ground
 * Secondary Waves
 * S Waves
 * they vibrate from side to side and up and down
 * Surface Waves
 * it moves more slowly than S waves and P waves
 * it causes most severe damage

Detecting Seismic Waves

 * geologists use seismographs to detect seismic waves

Measuring Earthquakes

 * geologists study the magnitude of all earthquakes
 * Mercalli Scale
 * it rates earthquakes according to their intensity
 * Richter Scale
 * rates size of seismic waves as measured by a particular type of mechanical seismograph
 * Moment Magnitude Scale
 * estimates total energy released by an earthquake

Locating the Epicenter

 * geologists use seismic waves to locate the epicenter