KHKZIBG+2.2

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=**2.2 Earthquakes**=

Vocabulary

 * focus**:the place under earth's surface where rock that is under stress breaks or folds, starting an earthquake.
 * epicenter**:the place on the surface right above the focus.
 * P waves**:earthquake waves that compress and expand the ground like an accordion.
 * face waves**: moves more slowly than P waves and S waves, but they produce the most severe ground movements
 * seismograph**:records the ground movements caused by seismic waves as they move though the ground.
 * magnitude**: a measurement of earthquake strength based on seismic waves and movement along faults
 * Mercalli scale**: developed to rate earthquakes according to their intensity
 * Ritcher scale**: the rating of the size of the size of seismic waves as measured by a type of mechanical seismograph.
 * Moment Magnitude Scale**: a rating system that estimates the total energy released from an earthquake.

Seismic Waves

 * P waves
 * come first
 * expand to make longer
 * S waves
 * come second
 * move up-and-down and side-to-side
 * Surface waves
 * gradually come

Detecting Seismic waves

 * uses seismograph

Measuring Earthquakes

 * The Mercalli Scale
 * rates earthquakes according to their intensity
 * The Ritcher Scale
 * rating the size of seismic waves
 * The Moment Magnitude Scale
 * estimates the total energy released by an earthquake.


 * Locating the Epicenter