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Earthquakes presentation
- 2. Section 1 & 2 Earthquake Formation
- 3. Fault formation When rocks undergo large amounts of pressure, the rock may break. When rocks break, they move along surfaces called faults.
- 4. What causes faults? Plates moving put stress on rocks near plate edges, causing rocks to bend compress, stretch, or break. Earthquakes are the vibrations produced by the breaking of rock.
- 5. How earthquakes occur Rocks move past each other at faults Rough surfaces catch Movement of fault is stopped Forces keep driving rocks to move This stress causes rocks to break, move along, fault, and return to original shape Earthquake occurs. Range from unnoticeable to devastating
- 6. 3 types of faults Normal Reverse (Thrust) Strike-Slip
- 7. Normal fault Tension causes rocks to be pulled apart Rock above the fault surface moves downward ANIMATION: http://earthquake.usgs.gov/learn/animations/animation.php? flash_title=Normal+Fault&flash_file=normalfault&flash_width=22 0&flash_height=320
- 8. Reverse faults Compression forces squeeze rocks Rock above reverse fault surface forced up and over rock below fault surface ANIMATION: http://earthquake.usgs.gov/learn/animations/animation.php? flash_title=Thrust+Fault+and+Reverse+Fault&flash_file=thrustfault&flas h_width=220&flash_height=320
- 9. Strike slip fault Rocks are moving past each other without much upward and downward movement-called shear Ex: San Andreas Fault ANIMATION: http://earthquake.usgs.gov/learn/animations/animation.php?flash_title=S
- 10. Seismic Waves Waves generated by an earthquake that travel through the earth Focus (foci if plural): point where energy release first occurs 3 types: Primary waves Secondary waves Surface waves
- 11. Primary waves P-waves Particles move back and forth in the direction that the wave is travelling Like waves through a spring
- 12. Secondary waves Secondary waves (s waves) Particles move at right angles to the direction of wave travel (up and down)
- 13. Surface waves Surface waves Particles move in a backward, rolling motion and side to side in a swaying motion Cause buildings to fall
- 14. Locating an Epicenter Different seismic waves travel at different speeds: Primary are fastest, then secondary, finally surface Scientists use the different speeds to determine distance to the epicenter
- 15. Measuring Seismic Waves Seismograph: measures the time seismic waves arrive
- 16. Seismograph Stations Seismographs are located all over the US and world If waves reach three or more stations, the epicenter can be determined Draw a circle around each station-the radius of each circle equals station's distance from epicenter Point where circles meet is epicenter
- 17. Bibliography Images "2010 Haiti Earthquake." Wikipedia. Wikimedia Foundation, 26 June 2012. Web. 29 June 2012. <http://en.wikipedia.org/wiki/2010_Haiti_earthquake>. "Earthquake Glossary." Earthquake Glossary. USGS, 2009. Web. 29 June 2012. <http://earthquake.usgs.gov/learn/glossary/>. "Fault (geology)." Wikipedia. Wikimedia Foundation, 29 June 2012. Web. 29 June 2012. <http://en.wikipedia.org/wiki/Fault_(geology)>. Information National Geographic Society, Ralph M. Feather, Susan L. Snyder, and Dinah Zike. Earth Science. N.p.: Glencoe, 2002. Print.