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<p>Earthquakes</p>
<p>Earthquakes</p>
<p>+What You Will LearnYou will learn about earthquakes and how they are measured.You will learn :what tools are used to measure earthquakeswhat scientists learn from measuring earthquakes+VOCABULARY:EarthquakeSeismology the study of earthquakesSeismologist a scientist who studies earthquakesEpicenter Seismic WaveSeismometer a tool scientists use to measure the strength of seismic wavesMagnitudeRichter Scale+Review:Lithosphere Tectonic plates are large slabs ofcrustthatmove onEarth's mantle. Faults are fractures in Earth's crust.</p>
<p>+</p>
<p>Three Types of Faults</p>
<p>Strike-SlipThrustNormal5What are Earthquakes?Vibrations in Earth'slithosphere caused bya sudden release of energy.The energy is released in the form of seismic waves, or waves that travel through Earth.</p>
<p>+2 Locations:The location below Earth's surface where an earthquake starts is called the hypocenter.The location on Earth's surface directly above the hypocenter is called the epicenter. </p>
<p>+Seismic WavesP waves, ("primary" or "compression" ) waves.shake the ground back and forth, parallel to the direction the wavesare traveling.P waves travel faster than S wavesS waves, ("secondary" or "shear) waves.shake the ground up and down, perpendicular to the direction the wavesare traveling. S wavesaremore destructive+Primary Waves (P Waves)A type of seismic wave that compresses and expands the ground</p>
<p>The first wave to arrive at an earthquake</p>
<p>+Secondary Waves (S Waves)A type of seismic wave that moves the ground up and down or side to side</p>
<p>+</p>
<p>Comparing Seismic Waves</p>
<p>+Surface WavesMove along the Earths surfaceProduces motion in the upper crustMotion can be up and downMotion can be aroundMotion can be back and forthTravel more slowly than S and P wavesMore destructive+Measuring Earthquakes:Seismographs, ("seismometers,)- instruments used to record earthquakes.Seismograms - the recordings made by the instruments.</p>
<p>+Typical Seismogram</p>
<p>http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt +Measuring Earthquakes: SeismogramsScientists use seismograms to determine the sizes of earthquakes.Magnitude:the size of an earthquake -a measurement of the amount of energy released during an earthquake.Richter Scale: a mathematical formula that assigns numbers to earthquakes. (size of the earthquake)+How do scientists calculate how far a location is from the epicenter of an earthquake? Scientists calculate the difference between arrival times of the P waves and S waves</p>
<p>The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves+Richter Scale:logarithmic, meaning that a difference of one unit represents a tenfold difference in size. For example, an earthquake measuring 5.0 on the Richter scale is 10 times larger than an earthquake measuring 4.0, 100 times larger than an earthquake measuring 3.0, 1000 times larger than an earthquake measuring 2.0, and so on.</p>
<p>+</p>
<p>Locating Earthquakes:Triangulation-a triangle has three sides, and it takes three different seismographs tofind the location of anearthquake's epicenter. The location wherethe three circles intersect, or cross each other,is the epicenter.</p>
<p>+Locating Earthquakes</p>
<p>http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM+Locating Earthquakes</p>
<p>http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM+Locating Earthquakes</p>
<p>http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM+</p>