RLAF+2.2

**Measuring Earthquakes**
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 * Vocab:** **Focus-** the pint beneath earth's surface
 * Epicenter-** the point directly above the surface
 * Seismic Waves-** vibrations that travel through earth carrying energy
 * P Waves-** Earthquake waves that expand and compress the ground
 * S Waves-** Earthquake waves that vibrates side to side as well as up and down
 * Surface Waves-** When P Waves and S Waves reach the surface some turn into surface waves
 * Magnitude-** A measurement of earthquake strength based on seismic waves
 * Mercalli Scale**- developed to rate earthquakes
 * Richter Scale-** A rating of the size of seismic waves
 * Moment Magnitude Scale-** a rating system that estimates the energy from an earthquake

**Seismic Waves**

 * like a drum
 * cause vibrations during an earthquake
 * vibrations travel through earth
 * carries energy
 * move like ripples in ponds

**Primary Waves**

 * earthquake waves
 * waves that expand like an accordion
 * first waves for earthquake
 * compress and expand ground

**Secondary Waves**

 * comes after P Waves
 * vibrate the earth
 * side to side
 * up and down

**Surface Waves**

 * move slowly, much slower than P & S waves
 * cause a lot of damage
 * P & S Waves form them

**Detecting Seismic Waves**

 * a good detector for earthquakes is the seismograph
 * seismograph is used to draw the waves while an earthquake is occurring
 * records ground movement

Measuring Earthquakes

 * magnitude is a measurement for earthquakes

**The Mercalli Scale**

 * describes how an earthquake affects people and buildings
 * is not very precise about its measurement
 * describes how an earthquakes affect people and buildings
 * is not very precise about its measurement

**The Richter Scale**

 * rates Seismic Waves
 * many geologist use the Richter Scale
 * used in modern times

**The Moment Magnitude Scale**

 * rates earthquakes sizes
 * measures every earthquake's magnitude
 * rates distance of earthquake

**Locating the Epicenter**

 * geologists use seismic waves to determine an earthquake's epicenter
 * the difference between P and S waves depend on how far an earthquake is
 * epicenter is the point where the most shaking occurs



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