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Earthquakes

Earthquakes. What Is An Earthquake? Click here to find out. 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 plate activity, . http://eqseis.geosc.psu.edu.

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Earthquakes

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  1. Earthquakes What Is An Earthquake? Click here to find out

  2. 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 plate activity, http://eqseis.geosc.psu.edu The map above shows the distribution of earthquakes with magnitudes greater than 5.0 that occurred between 1965 and 1995.

  3. Three Types of Faults Animation of fault movement Strike-Slip Reverse Normal

  4. Normal fault Pulls on the crust stretching rock so that it becomes thinner (like pulling on bubble gum) = tension Occurs when plates are moving apart Hanging wall Foot wall Results in hanging wall slipping downward animation

  5. What type of fault? normal Hanging wall Foot wall http://www.bgs.ac.uk/eqr/GeoD_Structures.htm

  6. What causes earthquakes? • Tectonic plates move past each other causing stress. Stress causes the rock to deform • What type of fault boundary is this? • What type of stress is shown? transform shearing

  7. Strike – slip fault Rocks on either side of fault slip past each other sideways with little up or down motion - What type of stress is produced? shearing Occurs at a plate boundary transform Animation of strike-slip motion

  8. Fault rupture across road in western Kaynasli, right-lateral strike slip displacement was about 4.0 m (13 feet) at this location http://www.geerassociation.org/GEER_Post%20EQ%20Reports/Duzce_1999/kaynasli1.htm

  9. Reverse fault Pushes on the crust squeezing rock until it folds or breaks (like a trash compactor) = Occurs when plates are moving together compression Hanging wall Foot wall Results in hanging wall slipping upward animation

  10. What type of fault? reverse Hanging wall Foot wall http://geologicalintroduction.baffl.co.uk

  11. What type of fault? http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  12. Focus – 1. point inside the Earth where an earthquake begins – 2. point on Earth’s surface above focus where earthquake is FELT most strongly Epicenter 2 1

  13. How Seismographs Work A seismograph is an instrument used for recording the intensity and duration of an earthquake. the pendulum remains fixed as the ground moves beneath it http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  14. Earthquakes • How are earthquakes measured? Seismogram – seismic wave display record Seismograph machine

  15. Seismic Waves

  16. Primary Waves (P Waves) • A type of seismic wave that compresses and expands the ground • The first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

  17. Secondary Waves (S Waves) • A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

  18. Comparing Seismic Waves

  19. Surface Waves • Move along the Earth’s surface • Produces motion in the upper crust • Motion can be up and down • Motion can be around • Motion can be back and forth • Travel more slowly than S and P waves • More destructive Animation of wave types

  20. 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

  21. Typical Seismogram How much time elapsed between the arrival of the P wave (start) and the arrival of the S wave (finish)? finish start http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

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

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

  24. Now you are going to be seismologists and locate an Earthquake http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM Go to: http://tinyurl.com/11quake13 Click here to go to virtual earthquake site

  25. National Geographic earthquake information

  26. How are Earthquakes Measured? Richter Scale A logarithmic scale used to express the total amount of energy released ___________ of an earthquake. Its values typically fall between 0 and 9, with each increase of 1 representing a _________ increase in energy. magnitude 10-fold

  27. How are Earthquakes Measured? Mercalli Intensity Scale A scale of earthquake intensity based on ___________ and ranging from I (detectable only with instruments) to XII (causing almost total destruction). observed effects Click for Interactive Demo Go to http://tinyurl.com/13quake13

  28. Earthquake Waves & Earth’s Interior Seismic wave animation

  29. Seismic Waves in the Earth Click here for animation http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  30. Tsunamis Click here for explanation of a tsunami http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

  31. Formation of a tsunami a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. PBS –tsunami animation http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

  32. With typical waves, water flows in circles, but with a tsunami, water flows straight. This is why tsunamis cause so much damage! Click here for Japan helicopter view of tsunami

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

  34. Review Questions 1. A large ocean wave usually caused by an underwater earthquake or a volcanic explosion. tsunami 2. Used to describe both a sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip earthquake

  35. How are Earthquakes Measured? 3. Which one uses a logarithmic scale to express the total amount of energy released or magnitude of an earthquake. Richter Scale 4. Which uses a scale of earthquake intensity based on observed effects and ranging from I (detectable only with instruments) to XII (causing almost total destruction). Modified Mercalli Scale

  36. What type of fault is shown by each picture? 1. 2. Normal Reverse Transverse or strike-slip 3.

  37. Which type of wave travels through solids only? S-wave

  38. Which type of wave causes the most destruction? Surface or Love waves

  39. What type of fault? Source: indiana.edu B http://geologicalintroduction.baffl.co.uk A Strike –slip or transverse fault Hanging wall has moved upward Reverse fault

  40. Focus – 1. point inside the Earth where an earthquake begins – 2. point on Earth’s surface above focus where earthquake is FELT most strongly Epicenter 2 1

  41. People walk along a damaged road in the province of Bohol on Tuesday, October 15, 2013. Do you think this was a major earthquake? Why or why not?

  42. Yes, it was a major quake. It crumbled a number of buildings Such as this church 7.1 magnitude earthquake hit the Philippines

  43. Earthquakes 3. Surface 1. P-wave 2. S-wave Seismogram ____________ seismic wave display record 4. Seismograph 5. __________ machine

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