C.K.K.K.+2.2

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=**Section 2 (2-2) Measuring Earthquakes**=

**Vocabulary**
P waves- earthquake waves that compress or expand the ground like an accordion. S waves- earthquake waves that is the kind of seismic waves and vibrate from side to side and also up and down. seismograph- a machine that records the ground movements caused by seismic waves and movement on the fault. focus- the place under the Earth's surface where rocks under stress breaks causing an earthquake. epicenter- the place in the surface right under the focus. seismic waves- it carries energy of earthquake and it vibrates. surface waves- a kind of seismic waves that are slower than P and S waves, but surface waves cause more ground movements. magnitude- a measurement of earthquake strength based on seismic waves and movements along faults. Mercalli scale- rates earthquakes according to their intensity. Richter scale- a rating of the size of seismic waves as measured by a specific type of mechanical seismograph. Moment Magnitude scale- a rating system that estimates the total amount of energy released by an earthquake

**Seismic Waves**

 * as seismic waves travel through the earth, they carry the energy of earthquakes
 * seismic waves carry this energy from the focus to the surface

**Earth**

 * earthquakes release 2 types of seismic waves
 * P waves and S waves
 * they travel in all directions and cause vibrations
 * after they reach the surface they become surface waves

**Earthquake Scales**

 * there is three scales used to measure earthquakes
 * the Moment Magnitude scale
 * used to determine magnitude of an earthquake
 * other scales
 * Mercalli scale
 * Richter scale

**Diagram of the epicenter**
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