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# Earthquakes! **Adapted from www.middleschoolscience.com.

## Presentation on theme: "Earthquakes! **Adapted from www.middleschoolscience.com."— Presentation transcript:

Earthquakes! **Adapted from www.middleschoolscience.com

What is an earthquake? Used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip Caused by volcanic or magma activity, Caused by other sudden stress changes in the earth.

Three Types of Faults Strike-Slip Thrust Normal

What causes earthquakes? Tectonic plates move past each other causing stress. Stress causes the rock to deform, break, and/or move

Elastic Rebound – deformed rock goes back to its original shape http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Focus – point inside the Earth where an earthquake begins Epicenter – point on Earth’s surface above focus

How Seismographs Work http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM the pendulum remains fixed as the ground moves beneath it

Typical Seismogram http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

Primary Waves (P Waves) PUSH-PULL PATTERN! – A type of seismic wave that pushes & pulls the ground The FIRST wave to arrive from an earthquake—travels the fastest! Travels Parallel to the direction the wave travels http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

Secondary Waves (S Waves) A type of seismic wave that moves the ground up and down or side-to-side (perpendicular) to the direction the wave travels Slower! More destructive to buildings http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

Comparing Seismic Waves **P & S Wave song: http://www.youtube.com/watch?v=w3NLexYxR7ghttp://www.youtube.com/watch?v=w3NLexYxR7g

Surface Waves Move along the Earth’s surface – ROLL OUT! Motion can be up and down, around & back & forth Travel more slowly than S and P waves – Last to arrive Most destructive to structures

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 The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

How are Earthquakes Measured? Richter Scale-measures energy

How are Earthquakes Measured? Mercalli Scale-measures damage Click Link for Interactive Demo http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

Earthquake Waves & Earth’s Interior **See how seismic waves move through the Earth’s layers here (Shadow zone): http://www.classzone.com/books/earth_science/terc/content/visualizations/es1009/es1009page01.cfm http://www.classzone.com/books/earth_science/terc/content/visualizations/es1009/es1009page01.cfm

Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Tsunamis http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Formation of a tsunami http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

Tsunami Warning System http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

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