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Earthquake Introduction Notes. Earthquake Causes. As the crust tries to move, pressure builds When crust finally moves, pressure and energy is released. Released as Seismic Waves. Three Seismic Waves (review). Surface waves- Move on Surface – damages stuff on Surface.
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Earthquake Causes • As the crust tries to move, pressure builds • When crust finally moves, pressure and energy is released. • Released as Seismic Waves.
Three Seismic Waves (review) • Surface waves- Move on Surface – damages stuff on Surface. • Primary waves – Move into and through Earth • Secondary waves – Also move into Earth
Different Sized Earthquakes • Bigger quakes release more pressure • Smaller quakes release less pressure • Pressure builds more when rocks in crust are very strong and bumpy. Since crust gets stuck and holds, more energy and pressure
Where Earthquakes happen (copy picture) Focus- Point underground where land actually moves. Start point of quake. Epicenter – point on surface directly above focus. Quake strongest here.
Measuring Earthquakes • Two Methods to Measure • Richter Scale – Measures magnitude (strength) of quake. Looks at how much energy is released. • Mercalli Scale – Measures intensity (damage/feels like) of quake. Describe damage